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The implications of global warming of
1.5ºC and 2ºC
Professor Sir Robert T. Watson FRS Professor Corinne Le Quéré FRS May 2018
Tyndall Centre for Climate Change Research Working Paper 164
The implications of global warming of 1.5ºC and 2ºC
Summary Report
Robert T. Watson - University of East Anglia
Corinne Le Quéré - University of East Anglia [email protected]
Tyndall Working Paper 164, May 2018
Please note that Tyndall working papers are "work in progress". Whilst they are
commented on by Tyndall researchers, they have not been subject to a full peer review.
The accuracy of this work and the conclusions reached are the responsibility of the
author(s) alone and not the Tyndall Centre.
The implications of global warming of 1.5ºC and 2ºC
Summary Report
Authors: Robert T. Watson and Corinne Le Quéré
Tyndall Centre for Climate Change Research, University of East Anglia
This summary report is based on research examining the implications of global warming of 1.5°C and
2°C project funded by (1) the UK department for Business, Energy and Industrial Strategy (BEIS) and
conducted by researchers at the Tyndall Centre and collaborators, and by (2) the Natural Environment
Research Council (NERC) and conducted by researchers at various universities. This summary is not a
critical assessment of these papers compared to others in the literature. Contributors listed in the
Appendix are gratefully acknowledged for their input.
This report contains research material that is not yet published and may be under embargo. Therefore
please do not share the report, and direct any requests to Asher Minns at the Tyndall Centre at
May 2018
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Outline
Introduction
Executive Summary
Part I: Context
• Historical and current emissions of greenhouse gases (GHGs)
• Implications of the Paris agreement pledges
• Fifth IPCC Report
Part II: Answers to Questions (combinations of questions requested by BEIS)
A: What are the implications of different interpretations of the 1.5ºC goal for impacts and emissions
pathways, and what global and regional rates of decarbonization are needed and when would net zero
emissions need to be reached to limit temperature rise to 1.5ºC compared to 2.0ºC. What are the key
assumptions?
B: What are the global and regional opportunities, challenges and risks of different mitigation strategies
and technologies to limit temperature rise to 2°C and 1.5°C? What major technological developments
are required and feasible are they, and what are the major technological uncertainties?
C: What are the societal and behavioural changes required to achieve these transformations and
their challenges?
D: What are the differences in the global and regional impacts and risks on human-related systems
between global warming of 1.5ºC and 2ºC, from both the resulting climate change and the
pathways needed to limit temperature rise? And are there any other benefits other than avoided
impacts? What are the uncertainties surrounding estimates of the impacts and how well can we
distinguish between the impacts at 1.5°C and 2°C?
Introduction
BEIS requested that the research and this report address a series of questions (listed in Annex1). Many of
the questions are over-lapping and have been integrated into those listed in the outline above, and one or
two of them cannot be answered as the research did not encompass the issues addressed in the questions,
e.g., the economic costs of stabilizing at 1.5°C and 2°C.
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Executive Summary
Context
• Global carbon emissions from fossil fuel burning, which reached an all-time high in 2017 after being
nearly constant during 2014-2016, need to peak imminently and decline rapidly to have any
possibility of achieving the Paris commitment of limiting warming to well below 2ºC;
• The current pledges under the Paris agreement are insufficient to limit global mean temperature
increases relative to pre-industrial levels to well below 2ºC. Instead global mean surface temperatures
will probably increase by around 3ºC, or more, and 1.5ºC will likely be exceeded in the decade of the
2030s and 2ºC in the 2060s;
• Global emissions from CO2 and other GHGs need to decrease to approximately zero to stop warming
at any level. Zero emissions from energy use can be achieved in principle, but because of expected
residual emissions of CO2 from some sectors (e.g. aviation, some industry), from non-energy use,
from other GHGs related to agricultural processes, removal of CO2 from the atmosphere (here called ‘negative emissions1’), e.g. through reforestation or Biomass Energy with Carbon Capture and
Storage (BECCS), will be necessary to stabilize any temperature rise.
Cumulative Carbon Emissions
• The cumulative CO2 emissions allowed post 2017 to achieve the 1.5ºC and 2ºC goals, because these
temperature goals are so near in the future, are dominated by uncertainties, ranging from about 100 to
800 GtCO2, and about 800 to 1700 GtCO2, respectively. These results are mostly higher than those
reported in 5th Assessment report of the IPCC2, but they include a limited number of studies only. The
IPCC special report on 1.5ºC to be published in October 2018 will provide an updated assessment.
• Estimates of the allowable amounts of cumulative carbon to achieve climate goals are dependent
upon: the probability (e.g., 50% versus 66%) of limiting climate change below a specified
temperature; the future evolution of non-CO2 emissions (especially methane and aerosols); the
magnitude of the carbon feedbacks through carbon released from natural wetlands and permafrost
thaw; the uptake of CO2 by the oceans; and the details of the calculations regarding the level of
present-day warming.
Peak emissions and rates of emissions reductions
• Rates of CO2 emissions reductions needed to meet the Paris climate commitments are stringent in all
reported publications, but the exact amplitude varies because the rate is highly dependent on: (i) the
cumulative CO2 emissions allowed; (ii) whether the model assumes an overshoot of the temperature
goal followed by negative emissions to bring temperatures back down; and (iii) whether the model
assumes emissions reductions start immediately or whether the emissions follow the NDCs3 until
2030.
• Similarly, it is urgent that global emissions peak soon to meet any scenarios consistent with the Paris
temperature goals. The vast majority of published scenarios that meet the 1.5ºC goal have peak emissions in the coming decade, even when considering overshoot followed by large-scale negative
emissions. All scenarios have a trade-off between the time of peak emissions and the amount of
BECCS deployed, whereby an earlier peak reduces the need for BECCS and other negative emissions
technologies and vice versa.
1 Negative emission technologies are also used in model projections to offset emissions at any level. 2 IPCC 5th Assessment Synthesis Report http://www.ipcc.ch/report/ar5/syr/ 3 The Nationally Determined Contributions (NDCs) are the pledges submitted to the UNFCCC under the Paris Agreement. Their mitigation goals mostly refer to year 2030.
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• Scenarios using the IMAGE integrated assessment model project annual rates of change in global
CO2 emissions in the 2020s of around -4.0%, and -2.5%, to achieve the 1.5ºC and 2ºC goals with a
66% probability respectively, assuming CCS is deployed at scale from 2020 and BECCS from 2030.
Excluding BECCS and other negative emissions technologies, the emission reduction rate for the 2ºC
goal was found to be slightly above 3% in the 2020s. Faster required rates of -5.4% and -2.7% to
achieve the 1.5ºC and 2ºC goals, respectively, were found using a simpler model with no CCS. As
these rates are global, faster rates need to occur in industrial countries to offset some growth
associated with development elsewhere.
• In the past decade, eighteen countries including the UK have decreased their emissions, largely due to
reduced energy demand (including energy efficiency) and deployment of renewable energy
technologies, but the average rates of -2.6% per year still fall short of the rapid rates needed to
achieve the Paris temperature goals.
The date to reach net zero emissions4
• The factors that influence the rates of emissions reductions also influence the date to reach net zero
emissions.
• Net zero global CO2 emissions were reached around 2050 and 2075 respectively, in the IMAGE
scenarios that achieve the 1.5ºC and 2ºC goals with a 66% probability, allowing for overshoot and use
of BECCS. A separate analysis with emissions following the NDCs until 2030 found comparable
results, with requirements to reach net zero around 2045 and in the 2080s for the 1.5ºC and 2ºC goals,
respectively. Note that the date to reach net zero for all greenhouse gases was not analysed here.
• If BECCS and other negative emissions technologies prove not to be technically, environmentally,
socially or economically viable at the scales assumed in the models, with only reforestation and
afforestation removing carbon from the atmosphere, emissions need to decrease to levels near zero
more rapidly, although small levels of above-zero emissions can remain during the full century.
• The date for the UK to reach net zero CO2 emissions was examined in one study using a simple
model initialised from current emissions. When assuming the global cumulative emissions are shared
based on equal per-capita emissions and BECCS is deployed at scale in the UK, but not including
equity measures for past responsibility, the year of net zero in the UK was similar to or slightly earlier
than that for the world. This result is particularly sensitive to a range of choices, including to various
measures of equity, and needs to be examined further.
Biomass energy with carbon capture and storage (BECCS)
• Most projections that keep warming below 2ºC rely heavily on the use of BECCS at large-scale to
produce negative emissions.
• However, there are critical uncertainties associated with the technical, economic and environmental
feasibility of BECCS. For example:
o this technique has not been demonstrated at the scale required and has received to date little
financial and political support;
o the required rate of deployment is extremely ambitious in many scenarios, exceeding in places the
historical rates for market uptake of fossil, renewable and nuclear technologies, and is entirely
dependent on incentives;
4 The term ‘net’ zero emissions refers to the sum of positive emissions plus removals. It can thus be achieved by reducing positive emissions to zero, or offsetting positive emissions by the active removal of GHG from the atmosphere.
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o its environmental and ecological sustainability, and therefore effectiveness, is questioned, in part
because two-thirds of the bioenergy crops are projected to be grown in regions with weaker
sustainability governance; and
o if BECCS involves replacing high-carbon content systems (e.g. boreal forests) with crops, then
afforestation and avoided deforestation are often more efficient for atmospheric CO2 removal
than BECCS.
• The significant issues raised on the plausibility of large-scale deployment of BECCS need to be
urgently addressed through a combination of finance, deployment, and research. Governments should
be very cautious on relying on this technology to meet the Paris commitments until large scale
deployment is set in motion. In the meantime, increased emphasis on an immediate and rapid
transition to a low-carbon economy is needed, in both the production and use of energy, as well as
aggressive mitigation of all sources of CO2 and other GHG emissions from all sectors.
Mitigation technologies and options
• Within most models, energy demand is poorly characterized compared with energy supply.
Consequently, highly ambitious decarbonisation of energy supply is considered in detail, whilst
opportunities for more aggressive reductions in energy demand are seldom included in future
projections therefore providing additional mitigation opportunities than are currently captured.
• While the energy transformations to achieve zero emissions are possible in some sectors (e.g.
buildings), zero emissions are currently thought to be unobtainable with foreseeable technologies in a
small number of critical sectors, including shipping, aviation and some industrial activities (e.g.
production of chemicals).
• In the IMAGE model, most mitigation in the critical sectors occurs through improvements in CO2
intensities, followed by energy intensities, but with a minimal use of reduction in energy demand. The
potential to reduce emissions varies widely by sector. For example, in the IMAGE model:
o Shipping and aviation: Limited decarbonization for shipping (half current emissions by 2100)
and aviation (no reductions by 2100) are achieved through a combination of fuel switching and
energy efficiency improvements, but emissions could also be reduced through slow steaming (for
shipping) and mode shift (for aviation) and some reduction in demand;
o Road transport: Rapid reductions in road transport emissions of up to 6% per year are achieved
through a combination of fuel switching, new technology vehicles, new low-carbon electricity
supplies and highly efficient vehicles, but additional mitigation could come from synthetic low-
carbon liquid fuels, modal shifts for passengers, smart road/cars, shifting freight to rail, and
demand management;
o Industry: Reductions in industry emissions of up to 4.5% per year are achieved mainly through
deploying industrial CCS in this relatively energy efficient sector, with additional mitigation
potential requiring a re-design of industrial processes to achieve a more efficient use of resources
and reductions in service demand through material efficiency and the circular economy.
Alternative options could include further electrification and fuel switch and increasing material efficiency.
• Achieving transformations in energy systems will require societal and behavioural changes, with the
following overarching issues and opportunities being identified globally:
o Given public opposition to certain low-carbon strategies (e.g. reduced indoor heating), it is critical
to increase public participation (e.g. via deliberative focus groups) in mitigation policy-making
and implementation, capitalizing upon public support for sustainable energy sources and
efficiency measures;
o Renewables are preferred as sources of energy, with nuclear and fossil fuels garnering the least support. Opposition to large-scale energy infrastructure often stems from perceived risks and poor
community engagement. Householder adoption of solar PVs is driven primarily by financial
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considerations as well as a desire to be environmentally-friendly. Biomass energy is
comparatively under-researched, with most concerns related to sustainability. There is low public
awareness of Carbon Capture and Storage (CCS), with mixed views about its benefits and risks
amongst those who do know about it.
o In principle the public are positive about energy efficiency measures, but barriers exist to the
adoption of measures (e.g. initial cost, habit). Demand-side reduction through restrictions on
energy services are often resisted by individuals. Overall, there is more public support for ‘pull
measures’, e.g., public transport, than ‘push measures’, e.g., increased taxes/tolls which may
restrict individual freedom. Behaviour change interventions have achieved energy savings of 5-
10%.
o There is potential to reduce emissions through disruptive innovations offering goods and services
with novel attributes to consumers, e.g., car-sharing, mobility-as-a-service, electric vehicle
integration with electricity grids, internet-enabled appliances, digitally-enabled food waste
reduction schemes, modular urban farming and smart infrastructure. These reductions are not
typically included in model projections. Scaling up evidence from early-adopter groups to the UK
population as a whole suggests additional emission reduction potentials of up to about 10% across
food, mobility and buildings.
Policies
• According to results based on the E3ME macro-economic model, policy measures needed to limit
warming to 1.5ºC are largely based on scaling-up existing and proposed measures, bringing forward
time scales of implementation and coordinated global actions, and tackling all sectors of the
economy. This includes ambitious levels of action through taxes, subsidies, efficiency incentives and
direct regulations. While substantial near-term green growth GDP and total employment gains are
possible in fossil fuel importing countries, in exporting countries there are generally negative impacts
on GDP and employment. Non-action and delayed action by individual countries and groups of
countries have a negative economic effect in the near-term on the country avoiding action, because of
increased dependence on energy imports, stranding of fossil-fuel assets and missing the benefits of
investment in low-carbon technologies.
Impacts and risks on human-related and ecological systems
• For most sectors and ecological systems, the impacts of climate change are reduced significantly by
reducing warming from 3.7ºC to 2ºC, and the impacts are statistically lower at 1.5ºC than at 2ºC.
• Losses in 2100 relative to the observed 1961-1990 climate for temperature changes of 3.7ºC5, 2ºC and
1.5ºC are projected to be (i) 13%, 5.1% and 3.7%, for crop yields; (ii) 550, 69, and 54 trillion $ for
net present value (NPV); (iii) 310, 61, and 30 millions of people affected by 100-year fluvial flooding
events; and (iv) 190, 87, and 64 millions of people at risk from drought in any given month;
• Considering climate change alone, limiting global warming to 1.5ºC above pre-industrial levels
avoids half the risks associated with warming of 2ºC for plants, animals, and insects in terms of
climate change induced range loss, and areas which benefit the most in terms of avoiding declines in
species richness are Southern Africa, Southern Europe and Australia.
• Temperature overshoot can have significant negative effects on ecosystems if they persist long
enough that rapidly-dispersing species can over-adapt to new conditions, and then need to retreat.
Temperature changes are projected to lead to extreme risks to population health affecting the ability
to perform essential activities of daily living such as physical work, across many tropical and sub-
tropical regions in response to future global warming of 1.5°C, and become widespread in these
5 A reference scenario with no climate policy beyond the Cancun pledges.
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regions around global warming of 2.5°C to 3°C. The exact population exposed depends on the
specific choice of thresholds, but conservative estimates are in the tens of millions, while top-end
estimates are in the billions of people.
• Projected changes in sea level in the 1.5ºC and 2ºC scenarios are lower in 2100 by 20-30 cm, and
substantially lower in 2300 by 2-3m compared to a scenario that exceeds 4ºC. Even under climate
stabilization, sea level rise continues over multiple centuries. Millions of people are projected to be
displaced under all scenarios without additional adaptation measures.
• Projected levels of ocean acidification for the 1.5ºC and 2ºC scenarios in 2100 are of about 10% and
30% higher acidity respectively, compared to the average level between 1986 and 2005. These levels
mean waters become increasingly corrosive to carbonate shells, with the worst effects to occur in
winter at high latitudes of both poles. Global mean ocean acidification stabilizes within a century
under both scenarios.
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Part I: Context
Historical and current emissions of greenhouse gases
Despite overwhelming scientific evidence that increased atmospheric concentrations of greenhouse gases
cause human-induced climate change, with predominantly adverse effects on socio-economic sectors,
human health and ecosystems, climate action has been delayed and global GHG emissions have continued
to increase steadily from 38GtCO2-eq in 1990 to about 54GtCO2-eq in 2017. In spite of the Paris
agreement, fossil fuel CO2 emissions in 2017 reached an all-time high, following three years of nearly no
growth. This increase illustrates the challenge of meeting the Paris agreement.
Implications of the Paris agreement pledges
As part of the Paris Agreement, 162 pledges were submitted to the UN Climate Change Convention
describing how each country intends to tackle climate change. These pledges cover 189 countries
accounting for 98% of global GHG emissions6. The Paris Agreement indicates a commitment by
countries to combat climate change by limiting global mean temperature increase well below 2ºC by 2100
relative to pre-industrial levels, and pursuing efforts to limit warming to 1.5ºC. However, the current
pledges must be implemented and strengthened as soon as possible.
To keep warming well below 2ºC, global GHG emissions should be reduced by about 20-25% in 2030
compared to now, according to the UNEP gap report7, assuming continued deep decarbonisation and
significant uptake of CCS and BECCS afterwards. Without the Paris Agreement pledges, emissions are
projected to increase by about 20%. If the unconditional pledges are implemented, global GHG emissions
are expected to increase by about 6% in 2030, while they would remain about the same with the further
implementation of the conditional pledges.
The current pledges under the Paris agreement therefore fall far short of what is necessary to limit global
warming to well below 2ºC. With current pledges and assuming CCS and BECCS deliver, warming of
around 3ºC is projected. With a total failure of the Paris Agreement, warming would be higher at around
4ºC, according to the UNEP gap report. Without an urgent and significant strengthening of the pledges,
1.5ºC will likely be the mean temperature rise in the decade of the 2030s and 2ºC in the 2060s.
Fifth IPCC Report
The last report by the IPCC was published in 2013-2014 (called IPCC AR5). It established the scientific
and technical basis associated with limiting warming to less than 2°C compared to pre-industrial levels
(taken as 1861-1880) with a probability of >50%, and >66%, but included relatively little detail on these
scenarios. IPCC AR5 made clear that in order to limit climate change at any level, a fixed cumulative
budget of CO2 could be emitted, and it provided this cumulative budget for various temperature goals.
This budget and the uncertainties around it are discussed in detail below. Following the Paris Agreement,
6 President Trump has since announced that the US plans to withdraw from the Paris Agreement. 7 According to Rogelj et al. (2016; https://www.nature.com/articles/nature18307), global GHG emissions would
increase from current levels of 54 GtCO2-eq to: (1) 65 (range 60-70) GtCO2-eq in 2030 without the Paris Agreement
(+20%), (2) 55 (52-58) GtCO2-eq with unconditional pledges only (+6%), and (3) about current level at 54 (52-54)
GtCO2-eq with both conditional and unconditional pledges. The difference between the projected level of global
GHG emissions in 2030 with full delivery of all Paris Agreement pledges, and what is needed to stay well below
2ºC, i.e., the emissions gap, is 11 to 13.5 GtCO2-eq according to the UN Gap Report 2017, or 33% above the 2ºC
pathway (assuming CCS and BECCS work and are implemented at a global scale).
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the UNFCCC requested an analysis of the 1.5ºC goal from the IPCC. The IPCC report is expected
October 2018.
Part II: Answers to Questions
A) What are the implications of different interpretations of the 1.5ºC goal for impacts and emissions
pathways, and what global and regional rates of decarbonization are needed and when would net
zero emissions need to be reached to limit temperature rise to 1.5ºC compared to 2ºC. What are the
key assumptions?8
Emissions pathways consistent with different temperature commitments can vary depending on a number
of key issues discussed in this section. The key issues include the allowable cumulative greenhouse gas
emissions to achieve stabilization at 1.5ºC and 2ºC and the magnitude of any acceptable overshoot (where the temperature goal is first exceeded and then returns back to a lower level). These issues are in turn
influenced primarily by the magnitude of the emissions of non-CO2 gases and by the feasibility of
delivering large-scale negative emissions. The chosen cumulative emissions and acceptable overshoots
then result in a given rate of decarbonisation and date by which net zero emissions are required, with the
options and opportunities discussed in Section B. The implications of the overshoot on key socio-
economic and ecological impacts are discussed in Section C.
Cumulative Carbon Emissions
Estimates of the allowable amounts of cumulative carbon emissions to achieve the 1.5ºC and 2ºC goals
are dependent upon the probability of achieving a specific goal (e.g., 50% versus 66%), the future
evolution of non-CO2 emissions (especially methane and aerosols), the magnitude of the carbon released
from natural wetlands and permafrost thaw, the uptake of CO2 by the oceans, and the details of the
calculations regarding the level of present-day warming. Because of the multiple choices, a broad range
of numbers has been published. The summary below includes the analysis done as part of this project,
compared to the numbers published by IPCC AR5.
IPCC AR5 reported cumulative emissions to climate goals from year 2010 with a probability of >50%,
and >66%, which we convert here to budgets starting from year 2017. Taking into account the emissions
from non-CO2 GHG, there are under 750 GtCO2 remaining for a >66% chance of 2°C, and 850 GtCO2 for
a 50% probability. The carbon budget falls to about 150 GtCO2 for a >66% chance of staying below
1.5°C, and 300 GtCO2 for a 50% probability (Table 1).
Combined uncertainties in cumulative budget approach: Table 1 shows a wide range of net cumulative
CO2 emissions allowed from 20179 from the different studies to achieve the 1.5ºC and 2ºC goals for 50%
and 66% probabilities (GtCO2), ranging from about 100 to 800 GtCO2 for the 1.5ºC limits, and about 800
to 1700 GtCO2 for the 2ºC limits. New results are mostly higher than those reported in IPCC AR5 based
on complex models, but they include a limited number of studies only. An IPCC special report on 1.5ºC
warming is expected October 2018 and will provide an updated assessment of cumulative emissions to
various temperature goals. The 1.5ºC goal in particular is so close in the future that the cumulative budget
approach for this goal is overwhelmed by uncertainties, although they are all extremely small (less than
about 20 years at current emissions levels).
8 A combination of questions 1 and the first part of 2. 9 All entries in the table have been converted to post-2017 emissions (from 01 January 2017) from those reported in
their papers.
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Table 1. Cumulative emissions of CO2 (GtCO2) allowed from 2017 to keep warming to various
commitment levels, from the most (left) to the least (right) stringent. The table includes values published
in the IPCC AR5 synthesis report, and the new studies detailed here. Numbers are rounded to nearest 10.
Study 1.5ºC (66%) 1.5ºC (50%) 2ºC (66%) 2ºC (50%)
IPCC AR510 150 300 750 850
van Vuuren11 110 770 1730
Goodwin12 720-750 790-830 1450-1510 1560-1620
Comyn-Platt13 530-720 1370-1730
Millar14 520-600 1220
Future Pathways based on the IMAGE Integrated Assessment Model: Van Vuuren et al. (2017)
considered a range of emission scenarios that achieve the Paris goals using the IMAGE model, which was
designed to explore emissions pathways consistent with the low end of climate change projections, and
has detailed representation of energy, particularly the supply side, and land use transformations. They
show that technology pathways still exist to reach the Paris agreement commitments of 1.5ºC and less
than 2ºC, but very stringent emission reductions will be needed, and like most model projections, the
model relies heavily on the use of BECCS at large-scale to produce ‘negative emissions’, later this
century. These pathways suggest that to stay below 1.5ºC requires emissions from 2017 to be about 110
GtCO2 (with 66% probability) and to stay below 2ºC requires emissions to be about 1730 and 770 for
50% and 66% probability, respectively (Table 1). The 1.5ºC goal is equivalent to only about one year of
current emissions, meaning that any further emissions would need to be offset by negative emissions in
the future and would create an overshoot in warming. The limitations of BECCS are discussed below.
Future Pathways based on theory and geological evidence: Goodwin et al (2018a) generated a large
ensemble of climate simulations consistent with both geological and historical observations of climate
change, and integrated these into the future to evaluate how much carbon can be emitted and still remain
under the 1.5ºC and 2.0ºC warming goals at different likelihoods. Their analysis suggests that to stay
below 1.5ºC requires emissions from 2017 to be about 730 GtCO2 and to stay below 2ºC requires
emissions to be about 1485 GtCO2, both for 66% probability and allowing no overshoot (Table 1).
Carbon Budget using the observational record: Millar et al. (2017a), using the historical observations
record to date, concluded that the remaining carbon budget for a 66% chance of achieving the 1.5°C goal
is likely to be significantly more than estimated by IPCC AR5. Using simple regression analysis between
cumulative CO2 emissions and global mean warming and assuming a 25% contribution of non-CO2
warming to peak warming gives an observationally derived best-estimate of the remaining 1.5°C carbon
budget of 880 GtCO2, or about 30 years of current emissions (Table 1; see also Millar et al. 2017b). The
study accounts for the uncertainty in historical non-CO2 radiative forcing using a standard detection and
attribution technique.
10 IPCC AR5 synthesis report Table 2.2, reported post 2010 values for cumulative carbon, using the period 1861-
1880 as reference year; these values are based on the complex models. 11 van Vuuren et al 2017 reported cumulative values from 2010 -2100, hence needed a major correction for post-
2017. 12 Goodwin et al 2018a reported post 2017 values for cumulative carbon. 13 Comyn-Platt et al 2018 reported post 2015 values for cumulative carbon with permafrost and methane feedbacks. 14 Millar et al 2017a reported post 2015 values for cumulative carbon – these values have also been corrected to fit
the observed temperature change since pre-industrial times, 1.01ºC rather than 0.93ºC.
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Effect of methane mitigation: Collins et al. (2018) modelled the impact of methane mitigation on the
cumulative CO2 budget. They found that reducing methane levels increased the equivalent of about 100
GtCO2 of allowable carbon emissions for every 100 ppb decrease in methane. For comparison, methane
concentrations have increased around 8 ppb per year in the past decade, therefore potential CH4
reductions still do not detract from urgent need to reduce CO2 emissions although they reduce the scale of
the mitigation needs. The most ambitious methane mitigation scenario (as captured by the difference
between a high and low CH4 scenario) was equivalent to an additional 862 GtCO2 by 2100 for the same
temperature goal, illustrating the importance of CH4 differences among scenarios for the cumulative
budgets assessments as shown in Table 1. They investigated both a monotonic increase to 1.5°C and an
overshoot returning to 1.5°C degrees. These did not differ greatly in terms of the allowable cumulative
carbon emissions, and the effects of methane mitigation were independent of the temperature pathway.
Methane mitigation also increased plant productivity and reduced air pollution with greater climate and
social benefits than assumed by IAMs, and hence identified a major deficiency/uncertainty in the
investigation of methane mitigation techniques and their costs.
Impact of permafrost thaw and natural methane emissions: Comyn-Platt et al. (2018) considered the
impact of permafrost thaw and natural methane emissions on the cumulative budgets, based on three
temperature profiles: two reaching 1.5°C by 2100 (a) asymptotically and (b) with an overshoot first to
1.75°C; and one profile reaching 2°C. The model results suggest that permafrost thaw and natural
methane feedbacks will reduce the total allowable anthropogenic CO2 emissions by about 200 GtCO2 up
to 2100 for both of the 1.5°C scenarios, and by 240 GtCO2 for the 2°C scenario, corresponding to a
reduction of approximately 4 and 5 years in emissions. Table 1 shows the corresponding post 2017
cumulative emissions.
Cumulative budget revision based on validation of oceanic CO2 uptake: Halloran et al. (2018) assessed
the oceanic uptake of atmospheric CO2 in the CMIP5 models underlying IPCC AR5, to assess the
reliability of given cumulative budgets. Where enough observational data exists for robust assessment,
CMIP5 models either overestimate or (within uncertainty) agree with observed trends in surface ocean
CO2 rise, implying that models underestimate ocean CO2 uptake trends. Assuming that this is not
cancelled by those areas where we can’t undertake robust comparisons, and that these trends continue (as
our results for the North Atlantic suggest), this implies that the CO2 emissions compatible with 1.5°C
degrees are higher than those provided by IPCC AR5. Therefore the budget may be higher because there
is greater capacity in the ocean sink than represented in the CMIP5 models.
Rates of emissions reductions
Rates of CO2 emissions reductions needed to meet the Paris climate commitments are stringent in all
reports, but the exact amplitude varies because the rate is highly dependent on: (i) the cumulative CO2
emissions allowed; (ii) whether the model assumes an overshoot of the goal followed by negative
emissions; and (iii) whether the model assumes emissions reductions start immediately or are delayed.
Scenarios using the IMAGE model project annual rates of change in global CO2 emissions in the 2020s of
about -4%, and -2.5%, to achieve the 1.5ºC and 2ºC goals with a 66% probability respectively, assuming
CCS is deployed at scale from 2020 and BECCS from 2030. Excluding BECCS and other negative
emissions technologies, the emission reduction rate for the 2ºC goal was found to be slightly above 3% in
the 2020s.
Goodwin et al. (2018a) reported faster required rates of -5.4% and -2.7%, using an idealized function with
no CCS (WASP Earth model), and assuming reductions started immediately. Faster rates of -4.5 % in the
2020s for the 1.5ºC goal were also reported by Comyn-Platt et al. (2018). For the 2ºC goal however, rates
of -3.8% are required if reduction begin in 2030 and -2.4% if they begin in 2020, probably reflecting
additional mitigation from methane in those scenarios.
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As these rates are global for the 2020s, faster rates need to occur in industrial countries to offset some
growth associated with development elsewhere.
The date to reach net zero emissions
Global CO2 emissions need to decrease to approximately zero to stop warming at any level. The date to
reach zero emissions is highly dependent on: (i) the cumulative CO2 emissions allowed to meet the chosen
climate goal; (ii) whether the model assumes an overshoot of the goal followed by negative emissions;
and (iii) whether the model assumes emissions reductions start immediately or whether the emissions
follow the NDCs until 2030.
Net zero CO2 emissions were reached in 2050 and 2075 respectively, in the IMAGE scenarios that
achieve the 1.5ºC and 2ºC goals with a 66% probability, allowing for overshoot and BECCS (figure 2).
Net zero CO2 emissions are needed about 30 years later when the probability and goals are changed from 2ºC with 66% probability to 2ºC with 50% probability (or 1.5ºC with 50% probability to 2ºC with 50%
probability), or when they are changed from 1.5ºC with 66% probability to 2ºC with 66% probability.
Limited BECCS mean reductions in CO2 emissions need to happen faster and reach levels near zero
earlier, coupled with larger contributions from other GHGs.
Figure 1: Different 1.5ºC and 2ºC emission pathways, 2010 – 2100. The scenarios are: (i) default 3.4 (3.4
W/m2 in 2100) has a 50% probability of staying below 2ºC in 2100; (ii) default 2.6 (for 2.6 W/m2 in
2100) has a probability of at least 66% of staying below 2ºC in 2100; (iii) no BECCS 2.6 is similar to
default 2.6 but it minimizes the use of BECCS and policies are set in place earlier; (iv) default 2.0 has
66% probability of staying below 1.5ºC and has an overshoot of about 0.2ºC. Adapted from van Vuuren
et al. (2017).
Figure 1 shows that emissions go negative around 2050 (default 2.0) and 2075 (default 2.6) in the
IMAGE model, thus requiring negative emission technologies to achieve the goals. Negative emissions in
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the below 1.5°C (default 1.9) and well below 2°C (default 2.6) scenarios shown in figure 1 amount to
about 750 and 200 GtCO2, respectively. However, it is important to recognize that there are biophysical
limits to carbon reduction techniques (afforestation, bioenergy and carbon storage), because of potential
undesirable effects on food security, biodiversity and risks related to CO2 emissions. But, to achieve the
1.5°C goal without overshoot would require CO2 emissions to decline to net zero around 2030-2035,
which is highly unlikely to be feasible, as is the potentially unrealistic levels of negative emissions (this
depends obviously on the uncertainty range for the carbon budget for 1.5ºC discussed earlier). Achieving
the 1.5°C goal, with or without BECCS, will be an extremely difficult challenge.
Similarly, Goodwin et. al. (2018b) concluded that assuming that the NDCs are followed to 2030, global
net emissions need to be restricted to net zero by year 2045 to achieve the 1.5ºC goal, with a possible
overshoot up to 1.7°C warming into the 2050s followed by net negative global emissions for the rest of
the century to bring warming back down to 1.5°C. For a 2.0°C goal, the best estimate for when global net
emissions must reach net zero is during the 2080s, with a range from as early as the late 2050s to the end
of the 21st century. The key assumptions for the timings are that non-CO2 emissions follow that
prescribed in RCP2.6.
When considering regional circumstances, it is expected that countries would reach net zero emissions in
different years depending on their current trajectories and the regional potential, capacity and willingness
to develop and deploy negative emissions technologies. Peters and Andrew (2018) developed a simplified
method to share the global mitigation burden among countries using two alternative assumptions, one
based on inertia/grandfathering and one on population. Under this simplified framework, the date for the
UK to reach net zero CO2 emissions is similar to or slightly earlier than the date to reach net zero
globally, when sharing cumulative emissions based on equal per-capita distribution and assuming BECCS
is deployed at scale in the UK. These results are similar to the 1.5ºC scenario of the IMAGE model for the
corresponding region (Western Europe), while in the 2.0°C IMAGE scenario, net zero is reached 10 years
earlier in Western Europe compared to the world. The factors influencing the year of net zero are complex
and intertwined, and include choices about burden sharing15, current emissions trajectories, the size of the
anticipated negative emissions, and the availability of local storage for CCS. As shown in Fig. 1, the year
of net zero is not necessarily a good indicator for the temperature goal, which can, in theory, be reached
without the need of achieving net zero emissions globally but by introducing more rapid mitigation
measures early on.
Challenges associated with Biomass Energy with Carbon Capture and Storage (BECCS)
BECCS is relied upon heavily in scenarios that limit global mean temperature increase to 1.5°C or 2°C as
a potential measure to offset residual emissions from the hard-to-decarbonise sectors, such as agriculture
and land-use change, aviation, shipping and industry (see below). BECCS also allows an overspend of
carbon budget so other sectors can decarbonize more slowly. Models tend to use large amounts of
BECCS assuming robust governance of bioenergy provision and significant policy support of CCS in the
near term, they emerge in models as cost-effective in a high carbon-tax world. However, there are critical
uncertainties associated with the technical, economic and environmental feasibility of BECCS. This
technique has not been demonstrated at the scale required and has received to date little financial and
political support. The specific issues to be addressed are described below.
BECCS in the IMAGE pathways: Vaughan et.al. (2018), analysed the key implicit and explicit
assumptions about BECCS in three low emission scenarios with the IMAGE model ranging from the
1.5ºC goal with 66% probability to the 2ºC goal with 50% probability. They concluded that:
15 See for example Robiou du Pont et al. (2017) https://www.nature.com/articles/nclimate3186
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• CCS deployment rates are very challenging compared to historical rates of deployment of fossil,
renewable or nuclear technologies and are entirely dependent on stringent policy action to incentivise
CCS;
• Half of all global CO2 storage occurs in USA, Western Europe, China and India and the storage
required is compatible with recent regional storage estimates;
• Biomass residues account for about half the bioenergy used and have fewer sustainability concerns
than energy crops;
• In the model, energy crops cannot be grown on forest or food production land. However,
implementing this in the real world is dependent upon robust regulatory frameworks at a regional
level;
• Poor governance of the sustainability of bioenergy crop production can significantly limit the amount
of CO2 removed by BECCS, through soil carbon loss from direct and indirect land use change. Only one-third of the bioenergy crops were grown in regions with developed governance frameworks;
• Ensuring BECCS delivers CO2 removal will require the development of robust and joined-up
approach for monitoring BECCS and tracking progress.
Harper et.al. (2018) explored the land-climate-carbon cycle interactions in a new 1.5°C scenario
(produced by the IMAGE group) that includes afforestation/reforestation/avoided deforestation and
BECCS, to remove CO2 from the atmosphere. Harper et al. (2018) assume all biomass is from energy
crops. They concluded that BECCS could be far less efficient for carbon dioxide removal than often
assumed, and that as a result, BECCS is unlikely to deliver the substantial negative emissions required to
stabilize at 1.5°C without significant overshoot. Harper et al. (2018) also argue that carbon removal
though BECCS, which is assumed in most 1.5°C or 2°C scenarios, is uncertain because it strongly
depends on underlying assumptions with respect to yields, land-use change emissions, and efficiency of
CCS.
In the IMAGE 1.5°C scenario, in order to meet the stringent requirements to stabilize at 1.5°C without
significant overshoot, bioenergy crops are assumed to replace some natural forests at high latitudes. This
is consistent with assumptions within IMAGE of high-yield bioenergy crops and efficient CCS, and that
~75% of the initial aboveground biomass is used for BECCS. However, Harper et al. (2018) found that
soil carbon emissions following the deforestation overwhelmed the carbon gains from bioenergy crops –
significantly reducing the efficiency of BECCS. The loss of soil carbon in regions with high initial carbon
density makes it difficult for BECCS to result in a net negative emission of carbon dioxide. In considering
these ambitious climate goals, we therefore need to consider the net impact of the avoided climate change
and the impact of the additional mitigation efforts required, i.e., a major challenge is to stabilize the
climate well below 2°C, without mitigation options (such as BECCS) producing worse negative impacts
than the additional climate change that they are designed to avoid.
BECCS and natural ecosystems: Harper et al. (2018) argue that if BECCS involves replacing high-carbon
content systems (e.g. boreal forests) with crops, then afforestation and avoided deforestation (and
presumably reforestation and forest restoration) are often more efficient for atmospheric CO2 removal
than BECCS. Hence, the development and monitoring of strong governance for the sustainable provision
of bioenergy is critical.
The significant issues raised on the plausibility of large-scale deployment of BECCS need to be urgently
addressed through a combination of finance, deployment, and research. Both biomass energy and CCS are
in use at small scale now, but they have not been combined and their large-scale deployment is untested.
Therefore, resolving the finance issues and setting deployment in motion may be the most useful next
step, beyond the many research and developments that are needed to resolve existing and emerging
issues. The state of knowledge on BECCS is currently insufficient to warrant the widespread assumption
used in model scenarios that they will work at scale. Governments should be very cautious on relying on
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this technology to meet the Paris commitments until large scale deployment is set in motion. In the
meantime, increased emphasis on a rapid transition to a low-carbon economy is needed, in both the
production and use of energy, as well as aggressive mitigation of all sources of CO2 and other GHG
emissions from all sectors.
B) What are the global and regional opportunities, challenges and risks of different mitigation strategies
and technologies to limit temperature rise to 2°C and 1.5°C? What major technological developments are required and how feasible are they, and what are the major technological
uncertainties?
Recent decarbonisation rates
Observed underlying drivers of decarbonisation in 18 countries: Le Quéré et al. (2018) examined the
emissions drivers over the decade 2005-2014 in 18 countries where emissions decreased the fastest16, representing 28% of the emissions. The median decrease in emissions was -2.6% per year (range of -4.6
to -0.9%). These countries are decreasing their carbon intensity (about -3.4% per year) faster than other
countries with higher GDP growth rates (typically much less than 2% per year). Among this group of
countries, decarbonisation was achieved through a decrease in energy demand, and an increase in the
deployment of renewable energy displacing fossil fuels. A distinct correlation was observed between the
number of energy and climate policies in place and the rate of decarbonisation. In principle there is no
inherent reason why these sustained decarbonisation changes in energy systems are specific to the
countries examined, thus, they could be expanded elsewhere.
Drivers of decarbonisation in models: The plasticity of energy demand coming out of the analysis of the
18 decarbonising countries appears to be larger than IAMs generally suggest. In their decarbonisation
scenarios, most IAMs project large increases in energy demand, matched by even larger deployment in
renewable energy and increased efficiency of fossil-based energy production (reductions of losses and/or
change of fuel type e.g. coal to gas). This behaviour is different from what is observed in the past decade
in the decarbonising countries, where demand has been the main trigger of emissions reductions, followed
by renewable energy deployment, with little change in the efficiency of fossil-based energy production.
The IMAGE model behaved more like the observations when it was used to produce low emissions
pathways, i.e., the 1.5ºC and 2ºC scenarios, compared to a baseline scenario of 3.7oC.
Therefore, the potential for near-term CO2 emissions reductions through changes in energy demand may
be underestimated in model projections. Further support for reductions in energy demand could tackle
consumption or efficiency of energy services and energy conversion in end-use technologies, with more
detailed representation of drivers of energy demand in models potentially helping to further explore the
solution-space for deep mitigation.
Sectoral analysis using the IMAGE model
Sharmina et.al. (2018) analysed the IMAGE model to show that most additional mitigation in critical
sectors occurs through improvements in CO2 intensities, followed by energy intensities, with minimal
reductions in service demand, except for aviation where growth in service demand in the 1.5ºC scenario is
half of that in the 2ºC scenario. This is high risk strategy. In contrast, a low risk strategy would mitigate
across all underlying drivers, i.e., service demand, energy intensity and CO2 intensity17,18.
16 Only countries where both the territorial and consumption emissions decreased were selected in this analysis.
International transport is not included. 17 Detailed analysis by sector is provided in the paper. 18 Decarbonisation rates for the 2020s by sector and region are available.
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Aviation and shipping:
• In the IMAGE scenarios:
▪ In the long term, the IMAGE scenarios project limited decarbonisation potential in both aviation
and shipping. By 2100, shipping emissions are about half of the present-day level, while
aviation emissions are around 20-30% below the present-day level. These significant and
ongoing emissions are, in most models, assumed to be compensated by the large-scale
deployment of BECCS;
▪ In the short to medium term, the IMAGE scenarios project modest cuts to absolute emissions
from both sectors. From 2030-2050, reductions of 1-3% per year in aviation CO2 emissions take
place. Shipping CO2 is halved over a period of 20 to 70 years, depending on the stringency of a
scenario;
• Both sectors are truly international, and decarbonisation rates are unlikely to vary significantly by
region, except if different carbon taxes are applied;
• Emission reductions in the aviation and shipping sectors (including those represented in IMAGE)
could be achieved using a combination of fuel switching, energy efficiency improvements, slow
steaming (for shipping), mode shift (for aviation), and some reduction in demand. The key risks for
air- or seaborne transport are weight constraints and long distance between re-fuelling stations. For
example, alternative energy sources and emission reduction technologies, such as CCS, are not
readily available for aircraft, given the crucial role of weight in aircraft design. Emerging
technologies towards electric planes are at early stages of development and while they are unlikely to
be deployed at scale in time, they could contribute to some efficiency improvement beyond current
scenarios provided they do not lead to increased demand. Low availability of stations around the
world for ships and aircraft to refuel using new and renewable fuels is another major constraint.
• Benefits from technology and operations are mainly incremental, though not fully exploited at the
moment.
• Demand constraints are likely required in stringent mitigation scenarios but hold risks to economic
development, particularly for export-led economies and small island economies dependent on sea
transport.
• International policy in aviation and shipping is currently not aligned with emission reductions
required over the next few decades, starting in 2020, to achieve the 2°C goal, let alone 1.5°C.
Road transport:
• In the IMAGE scenarios:
▪ Global road transport emissions decrease to nearly zero in the 1.5°C scenario by 2050, and in
the 2°C scenario by 2100;
▪ In the highest emitting world regions (including the USA and Western Europe), road transport
emissions decrease by 2050 at around 6% per year in the 1.5°C scenario until they reach net
zero emissions, while the 2°C scenario projects lower reductions in the short term, followed by
strong reductions later in the century;
▪ In the fastest growing regions (including Brazil, China, India and Indonesia), road transport
emissions fall gradually by 2050 and at a very high rate (around 6% per year) after 2050 in the
1.5°C scenario, while in the 2°C scenario they increase by around 2.4% per year by 2050 in the
and then fall rapidly by 5.4% per year thereafter;
• Emission reductions could be achieved through a combination of fuel switching with new technology
vehicles (e.g. electric vehicles (EVs) using batteries charged with low-carbon electricity, fuel cell
vehicles running on hydrogen), synthetic low-carbon liquid fuels replacing fossil fuels in internal
combustion engine vehicles (ICEVs), highly efficient vehicles, modal shifts for passengers, smart
roads/cars, shifting freight from road to rail, and demand management. There are a several
uncertainties related specifically to new technology vehicles;
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• One uncertainty is the reliability and practicality of fuel cell technologies. For example, fuel
contamination can affect the durability and stability of proton exchange membrane fuel cells. The
feasibility of upgrading the entire fuel distribution system for privately owned vehicles to support
hydrogen as an energy carrier is low in the short term. It may, however, be a solution for larger
vehicles such as trains and road freight vehicles;
• Another uncertainty is how much new low-carbon electricity will be available for plug-in vehicles
and for generating hydrogen (to be used in fuel cells or to create synthetic liquid fuels). Other sectors
will simultaneously need to shift to low-carbon electricity from fossil fuels, and grid output would
need to expand considerably to also power road transport. However, since EVs have better drivetrain
efficiency than ICEVs, less energy overall would be needed for electrified fleets;
• Another uncertainty is the rate at which the specific energy (energy per unit of mass), cost, reliability
and availability of large traction batteries for EVs can be improved to support acceleration of EV
production and market diffusion. The weight of batteries needed to provide the same range as ICEVs
reduces the overall efficiency of the vehicle, and so vehicles powered with liquid fuels are still better
all-round from a consumer point of view for some types of driving needs. Overall vehicle efficiency
improvements can ameliorate some of these issues. For freight, complete electrification is possible
but could require significant redesign of vehicles. Availability of rare metals needed for new
technologies (e.g. platinum for fuel cells, lithium for batteries) could slow down the expected growth.
• Finally, EVs can have higher embodied GHG emissions than ICEVs, and also possibly higher
lifecycle GHG emissions, depending on the GHG content of the electricity supply.
Industry:
• In the IMAGE scenarios:
▪ The average CO2 emission reduction rate in this sector between 2010 and 2050 is 4.4% per year
in the 1.5°C scenario and 1.2% per year in the 2°C scenario. During the second half of the
century, the emission reduction rates in the two scenarios are similar, at 4.1% and 4.5% per year
respectively;
▪ By 2100, industry’s global CO2 emissions in the 1.5°C scenario are around four times lower
than in the 2°C scenario;
▪ The largest regional cuts in CO2 emissions occur in the USA and Western Europe by 2050
(more than 7% per year) in the 1.5°C scenario;
▪ In the 2°C scenario, Brazil, India and Indonesia see modest growth in industry emissions in the
first half of the century, followed by relatively deep cuts of up to 6% per year between 2050 and
2100;
▪ Emission cuts are primarily achieved through reductions in CO2 intensity, through fuel
switching (most importantly to electricity) and potentially through deploying industrial CCS.
Energy efficiency improvements contribute to further emission reductions, although the
industrial sector is already highly energy efficient.
▪ There is limited representation of material efficiency and circular economy within IMAGE,
which primarily focuses on fuel switching and energy efficiency measures in industrial
processes, however, IMAGE does include some elements of material efficiency (e.g. recycled
scrap metal) and circular economy through lifestyle and economic variables, such as changes in
annual use of iron and steel (mn tonnes/yr) and changes in the mode of transport (billion
pkm/yr).
• Key challenges in decarbonising industry relate to the fact that the sector has had a long-standing
focus on energy efficiency as a cost-cutting measure and has all but exhausted the potential for further
emission reductions from efficiencies. Moreover, growing global demand for products and services is
leading to higher absolute emissions from production and manufacturing;
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• Mitigation for 1.5°C, while avoiding heavy reliance on an already-stretched low-carbon power
supply, requires a re-design of industrial processes to achieve a more efficient use of resources, and
hence reductions in service demand, through material efficiency and the circular economy.
Policy options
Holden et al. (2018), Mercure et al. (2018), and Pollit et.al. (2018) investigated two principal policy
scenarios, finding that the 1.5°C goal could be met if it was interpreted as a 50% probability of not
exceeding the 1.5°C goal, with a strictly limited amount of negative emissions and without excessively
high carbon tax. But this was only possible with urgent action by all major emitters and using all the
policy levers available (tax, regulation, etc.). This was found to be equivalent to 94% probability of
remaining below 2°C. A scenario with slightly weaker action on all fronts and reduced carbon tax giving
80% probability of remaining below 2°C was also investigated in detail. A 10-year delay by all countries
would make 1.5°C impossible although 2°C would remain feasible (1.8°C with 50% probability)19. The
team's 1.5°C 50% scenario expressed the most ambitious assumptions considered reasonable, more
stringent options were not investigated.
In Mercure et al. (2018) and Pollitt et al. (2018) the major opportunity for decarbonisation is presented by
a substantial near-term green growth GDP and employment gain which applies mostly in fossil fuel
importing countries, reinforcing decarbonisation policies and actions. In exporting countries there are
generally negative impacts on GDP and employment. The primary challenges are political rather than
technological. The effects of non-action and delayed action by individual countries and groups of
countries were investigated. In all cases this had a negative economic effect in the near-term on the
country avoiding action, in other words the opposite of a 'free-riding' effect applies. This result applied to
all seven country groups considered in all 335 scenarios modelled, to at least ~2040. No country acting
alone pushed the median warming from 1.5°C significantly above 2°C. Of the major emitting countries,
only China's withdrawal pushed the median close to 2°C. Withdrawal of the USA alone without
entrainment of other countries had little effect on global temperature.
Key assumptions include a maximum available BECCS potential of 150 EJ/year; no new government
borrowing (with any income or cost resulting from additional policies being equalised by compensation
of general taxation); sufficiently rapid improvements in energy storage and grid technology to support the
energy transition; reductions in process emissions at similar rates to power sector emission reductions,
and coordinated political action. Net zero global emissions were assumed to be reached shortly before
2060 by extrapolation of modelled trends up to 2050. Carbon-cycle uncertainties were investigated in a
fully coupled, ESM driven by realistic emissions for a ~1.5°C threshold, finding that carbon cycle
processes explained around half the uncertainty in the Earth System warming response to emissions.
However, the key finding was that for strong mitigation, uncertainties dominated the mean response
patterns, as mentioned before.
Pollitt et al. (2018) pointed out that most IAMs are more pessimistic than the E3ME model, which is
based on a disequilibrium dynamic simulation paradigm in contrast to most IAMs, which belong to a
class of neo-classical equilibrium based models. The E3ME model is generally more optimistic about
strong mitigation and the potential for green growth and involves a greater range of policies than most
other models. As noted earlier in this report, most IAMs appear to under-estimate the potential for
reductions in energy demand.
19 This modeling activity focused on the policies needed to reduce CO2 emission from the energy sector, but did not
explicitly address the policies required to reduce CO2 process emissions (e.g., from cement) and CO2 emission from
deforestation. Their model captured the carbon cycle aspect of deforestation by applying RCP LUC maps to genie,
and process emissions were scaled to energy emissions.
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Conventional IAMs have focused on determining the most economically efficient global energy system
compatible with a 2°C goal. These studies largely rely on global cost optimisation to set the level of
carbon taxation and on negative emissions. In the real world, climate policies vary widely across
countries and sectors. Regulations, subsidies, research programmes, and trade and investment frameworks
can all be combined to enhance diffusion of clean energy technologies, and to incentivise divestment from
high-emission alternatives. The E3ME-FTT-GENIE model uses observed technology trajectories,
together with a much wider portfolio of possible policy interventions, to estimate likely future pathways
of technology uptake. Another critical departure from conventional modelling is the inclusion of debt-
financed 'green growth' which is ruled out by most IAMs.
C) What are the societal and behavioural changes required to achieve these transformations and
their challenges?
Whitmarsh et. al. (2017)20, reported that attitudes often become more positive to technologies and policies
once they have been implemented, and people can experience the benefits and adapt to change. In
general, policies are likely to be resisted if seen as unfair or ineffective. Engagement processes are critical
to communicating benefits of action and implications of inaction; and for designing policies that are fair
and effective. Equally, engagement in technology design and siting decisions can improve outcomes
(including reducing opposition); and compensating communities where energy developments are sited is
also key.
• Societal and behavioural risks for the different mitigation strategies are centered on public opposition
to the requisite technology or policy. This is both for the supply side and the demand side (see details
below);
• Opportunities are focused on increasing public participation within mitigation policy-making and
action to improve decision quality, potentially reduce opposition to policies/technologies, and
generate pro-active engagement in a low-carbon transition. This includes (i) capitalising on public
support for sustainable energy sources and efficiency measures; and (ii) exploiting social influence
processes to help diffuse low-carbon innovations; and
• Engaging the public about carbon mitigation scenarios may influence behavioural intentions as well
as yielding important insights into public acceptability of transformative energy scenarios.
Supply side infrastructure
• Renewables: These are preferred as sources of energy, with nuclear and fossil fuels garnering the
least support (though cross-national variation). However, abstract support does not always translate
into local support due to challenges over siting of wind turbines, solar farms and hydroelectric plants,
largely due to risk perceptions or lack of engagement of local people in decision-making. Public
acceptance of large, energy infrastructures can be encouraged through early and substantive
engagement, as well as community benefits or ownership;
• Solar PV and small wind turbines: Householder adoption of solar PVs or small wind turbines is
driven primarily by financial considerations as well as a desire to be environmentally-friendly;
• Nuclear: Concerns remain high in many countries, especially following the nuclear disaster at
Fukushima. However, in U.S. and several other countries nuclear power remains relatively preferable
energy source where the benefits are viewed to outweigh the risks;
• Biomass energy: Comparatively under-researched, particularly in the configurations and scale
assumed in the 1.5ºC and 2ºC scenarios (large scale use of biomass energy and BECCS). Studies tend
to show lower awareness than with other renewables with most concerns related to sustainability,
local air pollution and impacts on land use, aesthetics and culture;
20 Whithmarsh et al. (2017) http://dx.doi.org/10.1098/rsta.2016.0376
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• Carbon Capture and Storage (CCS): While CCS is integral to most low-carbon scenarios, there is
currently very low public awareness. The informed public have mixed views: positive about the
potential to reduce emissions and provide employment, but concerns about risks (e.g. leakage) and
that CCS is only a temporary solution that does not reduce fossil fuel dependence21.
Demand side technologies and strategies
• Energy efficiency (EE): In principle the public are positive about energy efficiency, but barriers exist
to the adoption of EE measures, e.g., initial cost, inconvenience, habit, and often resistance to
changing behaviours, especially indoor heating and transport.
• Energy consumption: Demand-side reduction through restrictions on energy services are often
resisted by individuals. Restrictions on flying are likely to be particularly contentious, especially
amongst those who are frequent flyers. Overall, there is more public support for ‘pull measures’, e.g.,
public transport, than ‘push measures’, e.g., increased taxes/tolls which may restrict individual freedom;
• Behaviour change: Behaviour change interventions have achieved energy savings of 5-10%. Policies
targeting organisations, habits, high-impact or multiple behaviours are likely to be most effective.
• Load-shifting: Acceptability of load-shifting measures varies by device and conditions: e.g., delayed
dishwasher start is largely accepted, but intervention in fridges/freezers or heating systems is not due
to comfort and health concerns. Many are concerned about data inaccuracies and privacy with smart
meters;
• Electric vehicles (EVs): Most of the public perceive the current generation of EVs as a ‘work in
progress’ and too costly, despite offering environmental benefits. Other barriers to adoption include
limited rapid charging infrastructure, leading to ‘range anxiety’. Given the importance of familiarity
to the adoption of new (vehicle) technologies, social networks may be key to EV promotion;
Circular economy
Circular economy measures can contribute to reducing emissions beyond what is included in projections
and in the Nationally Determined Contributions. Industrial reconfiguration, such as circular economy,
will need to be considered not only at business and market level, but also at the consumer level. A
successful circular economy will require consumers to shift their perspective from one where they are the
‘end of the line’ for a product to one where they are an active intermediary in a closed-loop system that
aims to reduce, reuse, or recycle and recover materials. According to some estimates, less than a tenth of
the material in circulation is reused or recycled, indicating a large potential in this area.
Disruptive low-carbon innovations
Wilson et.al. (2018) analyzed the potential of disruptive low-carbon innovations to contribute to
achieving the 1.5ºC and 2ºC goals (Table 2), and assessed the status of the mitigation options used in
IAMs and low-carbon disruptive technologies in the technology life-cycle, from basic research to
maturity (Figure 2).
• Consumers are largely regarded as an obstacle to climate change mitigation; yet there are many end-
use goods and services that are both potentially appealing for consumers and potentially emission-
reducing;
21 It should be noted that there is currently no successful operational experience of CCS on a power-station. The
small Boundary Dam project (110MW) has operational difficulties and is only capturing a small proportion of the
carbon dioxide it was designed to capture.
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Internal report only, please direct requests to [email protected]
21
• The term ‘disruptive low-carbon innovation’ draws on business and management scholarship to
describe goods and services that offer novel attributes to consumers and that could become
mainstream to dislodge incumbent firms;
• Many disruptive low-carbon innovations could be identified at the fringes of mainstream markets
providing goods and services for mobility, food, housing, and cities;
• Novel attributes of disruptive low-carbon innovations of potential appeal to consumers include: (i)
versatility and diversity of functions, (ii) variety of choice, (iii) control and autonomy (iv),
relationships with others, (v) active involvement;
• Few, if any of these consumer-facing innovations are included or recognised in global systems
models of mitigation pathways; yet in-depth bottom-up studies find large emission-reduction
potentials from specific innovations; and
• Polices should recognise and enable the potential for disruptive low-carbon innovators to bring new
goods and services into mainstream markets.
Table 2: Potential Emissions Reductions of Disruptive Low-Carbon Innovations in the UK extrapolated
based on current preferences. Changes in preferences can lead to additional changes in emissions, both
reductions and increases.
Figure 2: Technology Life-Cycle for Mitigation Options in Global IAMs and Potentially Disruptive
Technologies.
PotentialDLCI Potentialannualemissionreductions
as%ofUKsectoral
emissions
mobility car-sharing 0.8to0.9MtCO2e 0.8-0.9%
e-bikes 0.04to0.08MtCO2e 0.04-0.08%
e-bikesharing 0.09MtCO2e 0.09%
mobility-as-a-service 1.4MtCO2e 1.4%
food
culturedmeat 0.02MtCO2e 0.03%
foodwastereduction 2.6to3.6MtCO2e 5.2-7.1%
urbanfarming 2.1MtCO2e 4.1%
reducedmeatindiet 0.7MtCO2e 1.4%
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D) What are the differences in the global and regional impacts and risks on human-related systems
between global warming of 1.5°C and 2°C, from both the resulting climate change and the
pathways needed to limit temperature rise? And are there any other benefits other than avoided
impacts? What are the uncertainties surrounding estimates of the impacts and how well can we
distinguish between the impacts at 1.5°C and 2°C?
Warren et al. (2018a) projected the regional and global climate change impacts in 5 sectors resulting from
the baseline emissions scenario used in the IMAGE model compared with the 1.5°C and 2.0°C scenarios.
This results in a comparison of the impacts of two different stabilisation levels and for two different
probabilities. The uncertainty in climate projections is considered by using warming patterns from six
General Circulation Models (GCM). Table 3 shows the absolute differences between the global aggregate
impacts at different warming levels in 2100. Figure 3 shows the percentage impacts avoided going from
the 2°C scenario to the 1.5°C scenario. Figure 4 shows the time evolution of global aggregate economic
damages as %GDP loss in a scenario in which global annual mean temperature rise to 3.66°C above pre-
industrial levels, in comparison with scenarios in which warming is constrained to below 1.5°C or 2°C
with 66% probability. In the no policy baseline (red line), temperature rises by 3.66°C by 2100, resulting
in global GDP loss of 2.6% (5-95% percentile range 0.5-8.2%), as compared with 0.3% (0.1 – 0.5%) by
2100 in the 1.5°C scenario (blue line) and 0.5% (0.1-1.0%) in the 2°C scenario (green line).Key messages
include:
• In most sectors and regions risks are avoided by constraining warming to the lower stabilization
level. Specifically comparing risks at 1.5°C warming rather than 2°C above preindustrial levels:
• Across sectors, the % impacts avoided globally varies from -3 to +62%, taking into account the
uncertainties from use of alternative GCM patterns in downscaling;
• Avoided global economic damages of 22% (10-26%) accrue by constraining warming to 1.5°C rather
than 2°C; 90% (77-93%) by constraining warming to 1.5°C rather than 3.66°C, and 87% (74-91%) by
constraining warming to 2°C rather than 3.66°C;
• The largest avoided impacts are for fluvial flooding and the lowest are for malaria where risks
actually decline with warming in the global aggregate;
• Changes in risks vary across and within regions. Risks increase already in the 2050s for crop yield,
dengue (risks) and malaria (benefits);
• In most places, risks increase with warming, however, in some locations there are non-linearities, i.e.,
there are places where risks are lower than at present with warming of 1.5°C and then higher than at
present with 2°C warming (e.g. for malaria, where the risk decreases at 1.5ºC and increases again
above 2ºC). Non-monotonic changes in precipitation can contribute to these non-linearities, issues
such as heat stress, crop yields and drought which are function of both precipitation/humidity and
temperature change;
Warren et. al. (2018a), quantified uncertainties using six climate models from the CMIP5 archive and by
conducting sensitivity analysis to model assumptions and parameters. The ranges in table 3 reflect model
spread. In general, the analysis could distinguish between levels of impacts at the two levels of
warming. Using a measure of % impacts avoided (rather than absolute benefits) is more robust, since the
% impacts avoided is less uncertain than the absolute levels of risk.
Table 3 shows the absolute differences between the global aggregate impacts at different warming levels
in 2100. Risks avoided are positive numbers. Error bars indicate the range of uncertainty associated with
the use of alternative regional climate change patterns associated with the different models.
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time Metric (with units) observed
climate
(1961-
1990) vs
1.5 (66%)
1.5 (66%)
vs 2 (66%)
1.5 (66%) vs
3.66
2 (66%) vs
3.66
Agriculture % Crop Yield Loss 3.7
(3.6, 3.9)
1.4
(1.3, 1.5)
9.3
(9.0, 9.8)
7.9
(7.6, 8.4)
Economy Damages as %GDP
loss in 2100
NPV of impacts
($trillion)
0.28
(0.11, 0.53)
54
(14, 121)
0.18
(0.02, 0.45)
15
(1, 43)
2.34
(0.36, 7.66)
488
(36, 1690)
2.16
(0.34, 7.21)
482
(34, 1663)
Coastal
Flooding
Cumulative land loss
due to submergence
(x103 / yr)
Not
available
14.0
(8.4-20.1)
78.9 (48.8-
108.5)
64.9 (39.5-
88.3)
Coastal
Flooding
People exposed to
coastal flood risk
(millions/yr)
Not
available
8.2 (4.6-7.3) 35.3 (26.4-
38.2)
27.1 (21.8-
30.9)
Fluvial
Flooding
Population living in
the modelled
inundation areas in
which the discharge
exceeds the 100-year
flood in 1961-1990
(tens of millions)
30.1
(6.6, 66.2)
31.1
(8.4, 56.4)
279.0
(101.7, 489.8)
247.9
(93.3, 433.4)
Drought Million people at risk
from a -1.5 SPEI 12
event in any given
month
63.7
(48.5, 95.5)
22.8
(17.3, 34.0)
125.4
(96.7, 125.4)
102.6
(79.4, 129.7)
Heat stress Hundred Million
People exposed to
moderate to extreme
heat injury risk
12.1
(10.9, 14.3)
3.9
(3.3, 4.8)
21.7
(20.6, 23.2)
17.8
(17.3, 18.4)
Malaria Million People at
risk of infection
456.7
(432.0,
480.8)
-9.9
(-20.7, -0.9)
-87.3
(-165.5, -25.4)
-77.4
(-144.8, -24.5)
Dengue Million People at
risk of infection
7.3
(6.8, 8.2)
0.8
(0.6, 1.2)
5.2
(3.8, 7.8)
4.4
(3.2, 6.7)
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Figure 3: Percentage Impacts Avoided Going from 2ºC and 1.5ºC scenarios
Figure 4: Global Aggregated Damage as a % of GDP for Different Scenarios
Climate Change and Biodiversity
Warren et al. (2018b), reported that considering climate change alone, limiting global warming to 1.5ºC
above pre-industrial levels avoids half the risks associated with warming of 2ºC for plants, animals, and
insects in terms of climate change induced range loss. Areas which benefit the most from constraining
warming to 1.5ºC as compared to 2ºC in terms of avoiding declines in species richness are Southern
Africa, Southern Europe and Australia.
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They present results from the first global scale assessment of climate change impacts on 19,848 species of
insects and found that 20±10% of these are projected to lose over half their range at 2ºC and 9±6% at
1.5ºC, even when the potential for species to disperse at a realistic rate to track their shifting climate
envelope. Given recent observed declines in insects, they found that limiting warming to 1.5ºC will be
important in preserving ecosystem functioning and services, especially those provided by insects such as
pollination, detrivory, herbivory, and nutrient cycling. These declines would also impact on insectivores
and their predators.
Corresponding analyses for 12,429 species of mammals, birds and reptiles and amphibians show that
8±5% of animals are projected to lose over half their range at 2ºC and 4±3% at 1.5ºC; and 16±10% of
73,224 plant species are projected to lose over half their range at 2ºC and 8±5% at 1.5ºC. Hence overall
across all taxa analyzed limiting warming to 1.5ºC compared to 2ºC reduces climate-change induced
geographical range loss by approximately 50%.
The IMPALA project quantified the terrestrial land areas potentially acting as climate refugia for 80,000
terrestrial plants, birds, mammals, reptiles and amphibians. Climate refugia are defined as areas where
>75% of the species currently modelled are projected to remain under the changed climate, according to
more than half of the regional climate change models. Warren et al. (2018b) used the IMPALA model to
qualitatively assess the implications of temperature overshoot, in particular highlighting how an overshoot
of half a degree (to 2°C as opposed to 1.5°C) would be expected to have significant negative effects on
biodiversity in terms of species range loss; and that if the overshoot persists for sufficiently long, species
that disperse rapidly might ‘over’ adapt by moving spatially to geographical areas that become newly
suitable for them, and then may need to retreat from these areas later as warming or precipitation changes
ameliorate. For species that do not disperse rapidly and which would be negatively affected by 2°C
warming, the longer the overshoot the less likely they are to be able survive in situ until the temperature
returns to 1.5°C.
The IMPALA model was also used to explore the role of natural adaptation by dispersal, showing how
important this is in allowing species to persist under climate change. This is particularly important for
birds, mammals, butterflies and dragonflies. Therefore, the slower the rate of temperature rise, and the
later we reach or pass the 1.5°C threshold, the lower are the impacts of climate change on biodiversity.
In the IMPALA project, uncertainties were explored associated with alternative projections of regional
climate change associated with 21 alternative regional climate change patterns from CMIP5. Whilst there
are uncertainties about the precise values of species’ range loss, such that the lowest value of range loss
for a species under 2ºC warming is often lower than the highest value under 1.5ºC warming, the ensemble
means across the regional climate model patterns consistently differ: there is no difficulty in detecting a
consistent difference between 1.5ºC /2ºC warming when using each individual GCM and hence the
ensemble as a whole.
Climate Change and Human Health
Andrews et al. (2018) reported that extreme risks to population health from heat stress appear across
many tropical and sub-tropical regions in response to future global warming of + 1.5ºC, and become
widespread in these regions around global warming of + 2.5ºC – 3ºC. The exact population exposed
depends on the specific choice of thresholds, but conservative estimates are in the tens of millions, while
top-end estimates are in the billions of people. Both workability and survivability are affected, however
more people are exposed to workability limits. Population exposed can increase suddenly within one
decade due to the non-linear interactions between regional climate variability and excessive heat stress
thresholds.
Climate Change and Sea Level Rise and Ocean Acidity
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Nicholls et al., (2018) reported that the proportion of global population exposed to sea-level rise in 2300
was projected at 2.0% for an aggressive mitigation scenario (1.5°C) and 5.4% for the non-mitigation
policy scenario (RCP8.5). Table 4 quantifies, with uncertainty limits, projected changes in sea level and
ocean ph for the 1.5°C, 2°C and RCP 8.5 scenarios, compared to a baseline of 1986-2005. Even though
temperature stabilizes in the 1.5°C and 2°C scenarios prior to 2100, sea levels continue to rise for several
more centuries, hence the need to quantify projected levels in 2300. Small islands, deltas and cities,
especially in India and China (Figure 5) are highly vulnerable to projected increases in sea level and
should consider preparing adaptation plans.
Table 4. Summary results of the WASP Earth System Model for global mean temperature, global mean
sea-level rise and ocean pH and the two stabilisation scenarios (1.5ºC and 2.0ºC) and the reference
unmitigated (RCP8.5) emissions scenario (projected temperatures shown in the table for 2050, 2100 and
2300). Results include the ensemble mean ± standard deviation and the 90% range (5th percentile to 95th
percentile) in brackets. Note that the 1.5ºC pathway stabilises temperature at 2045, and the 2.0ºC pathway
stabilises temperature at 2065.
Time Global mean temperature
(relative to pre-industrial)
(ºC)
Sea-level rise
(relative to 1986-2005
average) (m)
Ocean pH
1.5ºC 2.0ºC RCP8.5 1.5ºC 2.0ºC RCP8.5 1.5ºC 2.0ºC RCP8.5
1986-
2005
0.8±0.2 (0.7-1.3) 0.0 8.11±0.00 (8.10-8.11)
2050 1.5 ±
0.2
(1.2-
1.8)
1.8 ±
0.3
(1.4-
2.2)
2.1 ±
0.5
(1.6-
3.2)
0.21
± 0.04
(0.14-
0.28)
0.23
± 0.04
(0.17-
0.30)
0.26
± 0.04
(0.19-
0.32)
8.06 ±
0.04
(8.03-
8.15)
8.01 ±
0.04
(7.97-
8.11)
7.96 ±
0.01
(7.95-
7.97)
2100 1.5±0.1
(1.2-
1.6)
2.0±0.2
(1.8-
2.3)
4.1 ±
1.0
(3.0-
6.3)
0.39 ±
0.09
(0.24-
0.54)
0.49 ±
0.10
(0.31 -
0.65)
0.72 ±
0.11
(0.54-
0.91)
8.08 ±
0.04
(8.04 -
8.16)
8.02 ±
0.06
(7.95-
8.13)
7.75 ±
0.01
(7.74-
7.76)
2300 1.5±0.1
(1.4-
1.5)
2.0±0.1
(1.9-
2.0)
8.8±3.1
(5.5-
14.8)
0.89 ±
0.23
(0.53 -
1.27)
1.17 ±
0.29
(0.71 -
1.65)
3.65±0.8
9
(2.40-
5.27)
8.09 ±
0.04
(8.02 -
8.15)
8.04 ±
0.06
(7.95 –
8.13)
7.45±0.0
0
(7.74-
7.75)
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Figure 5: Number of People Flooded Annually (million per year) in 2100 for the 1.5°C, 2°C and RCP 8.5
scenarios (50th percentile) under SSP2, Assuming no Additional Adaptation
Jevrejeva et al. (2018) estimated a global sea level rise up to 52 cm (25 to 87) and up to 63 cm (27 to 112)
for a temperature rise of 1.5°C and 2.0°C by 2100 respectively. The additional 11 cm of sea level rise
between the 1.5 ºC and the 2 ºC scenario is projected to result in additional global annual flood costs of
US$ 1.5 trillion per year (0.25% of global GDP) without adaptation. Flood cost for UK is projected to
increase from 2.5% of GDP (1.5°C) to 4% GDP(2°C). Failure to meet either of the 1.5ºC and 2ºC goals
will clearly lead to greater economic costs and higher levels of costal risk worldwide.
Coastal sea level rise generally exceeds the global average, with exceptions of coastline in the areas close
to Greenland and Antarctic ice sheets. The largest differences between 1.5ºC and 2ºC scenarios along
coastlines are ~15 cm for median projections (up to 20 cm at 95th percentile) and occur for the USA east
coast and the small-island nations in the Pacific and Indian oceans.
By 2200 global sea level rise projections are up to 1m (50%) and 1.69m (95%) with 1.5ºC and 1.32m
(50%) and 2.22 m (95%) with 2ºC. The difference in sea level rise with warming of 1.5ºC and 2ºC could
be up to 0.32m for median (0.22-0.32) and up to 0.53m for the 95% percentile (0.37-0.53), almost 1/3 of
possible sea level rise of 1.0m (1.5ºC) and 1.32m (2ºC) by 2200. The largest gap in our understanding of
future sea level changes is due to Greenland and Antarctic ice sheet response to future warming.
Brown et al (2018), however, reported that the projected changes in 2100 overlap for sea-level and flood-
exposure for the 1.5ºC and 2.0°C scenarios, with the differences being small and hard to distinguish.
While the differences do begin to grow after 2100, the projected differences between the 1.5°C and 2.0°C
scenarios are small in comparison to the differences between either of these scenarios and the RCP8.5
scenario.
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Acknowledgements
This summary report is based on publications, some in draft form, from a number of researchers funded
by BEIS and NERC programmes examining the implications of global warming of 1.5°C and 2°C project.
The authors gratefully acknowledge access to early draft of publications and contributions of headline
findings from Bill Collins, Peter Cox, Pierre Friedlingstein, Jonathan Gregory, Gary Hayman, Paul
Halloran, and Svetlana Jevrejeva, as well as additional input from:
Sally Brown, University of Southampton and the Tyndall Centre
Neil Edwards, Open University
David Gernaat, PBL Netherlands Environmental Assessment Agency and Utrecht University
Phil Goodwin, University of Southampton
Clair Gough, University of Manchester and the Tyndall Centre
Anna Harper, University of Exeter
Emma Littleton, University of Exeter
Maria Sharmina, University of Manchester and the Tyndall Centre
Detlef van Vuuren, PBL Netherlands Environmental Assessment Agency and Utrecht University
Naomi Vaughan, University of East Anglia and the Tyndall Centre
Rachel Warren, University of East Anglia and the Tyndall Centre
Andrew Welfle, University of Manchester and the Tyndall Centre
Lorraine Whitmarsh, Cardiff University and the Tyndall Centre
Colin Whittle, Cardiff University and the Tyndall Centre
Charlie Wilson, University of East Anglia and the Tyndall Centre
We also thank Jolene Cook, Stephen Forden, Julie Maclean and others at BEIS for comments on previous
drafts of this summary report.
The Tyndall Centre project that underpins large parts of this report was managed by Asher Minns from
the Tyndall Centre at UEA, and supported by Alfie Kirk.
Final Report on the implications of global warming of 1.5ºC and 2ºC
Internal report only, please direct requests to [email protected]
31
Annex 1
BEIS requested that the research addressed the following series of questions. Questions 1bis, 2bis, 3bis,
4bis and 6 were requested at a later date than questions 1-5. Unfortunately, the research conducted does
not allow question 6 to be answered.
Question 1: What are the implications of different interpretations of the 1.5ºC goal for impacts and
emissions pathways?
Question 1bis: What are the global and regional implications for peaking emissions in a 1.5ºC scenario,
and how do they differ from 2.0ºC?
Question 2: What global and regional rates of decarbonization are needed and when would net zero
emissions need to be reached to limit temperature rise to 1.5ºC compared to 2.0ºC, and how can these be
achieved? What are the key assumptions?
Question 3: What are the global and regional opportunities, challenges and risks of different mitigation
strategies and technologies to limit temperature rise to 2°C and 1.5°C? What are the major uncertainties in
these?
Question 2bis: What are the societal and behavioural attitudes and changes required to achieve these low-
carbon transformations and their challenges?
Question 2bisa: What are the costs for different mitigation pathways, and what major technological
developments are required and feasible are they?
Question 4: What are the differences in the global and regional impacts and risks on human-related
systems between global warming of 1.5°C and 2ºC, from both the resulting climate change and the
pathways needed to limit temperature rise?
Question 4bis: And are there any other benefits other than avoided impacts?
Question 5: What are the uncertainties surrounding estimates of the impacts and how well can we
distinguish between the impacts at 1.5°C and 2ºC?
Question 6: What are the differences in probabilities of extreme temperature rise (i.e., risk of 4ºC+) under
a 1.5ºC vs 2.0ºC 66% trajectory? Do they vary depending on how 1.5ºC vs 2.0ºC are achieved? What are
the differences in the risk of tipping points and key feedbacks between 1.5ºC vs 2.0ºC?
Tyndall Working Paper series
2000 - 2018
The Tyndall Centre working paper series presents results from research which are mature enough to be submitted to a refereed journal, to a sponsor, to a major conference or to the editor of a book. The
intention is to enhance the early public availability of research undertaken by the Tyndall family of
researchers, students and visitors. They can be downloaded from the Tyndall Website at:
http://www.tyndall.ac.uk/publications/working_papers/working_papers.shtml
The accuracy of working papers and the conclusions reached are the responsibility of the author(s)
alone and not the Tyndall Centre.
Papers available in this series are:
• Watson, R. T.; Le Quéré, C. (2018). The
Implications of global warming of 1.5ºC and 2ºC Summary Report Tyndall Working Paper 164
• Wilson, C. (2017). Disruptive Low Carbon Innovation Workshops: Synthesis Report Tyndall Working Paper 165
• Nunes, A. R.; (2016) Assets for health: linking vulnerability, resilience and adaptation to climate change Tyndall Working Paper 163
• Rayner, T.; Minns, A; (2015) The challenge of communicating unwelcome climate messages Tyndall Working Paper 162
• Le Quéré, C., Capstick, S., Corner, A., Cutting, D., Johnson, M., Minns, A., Schroeder, H., Walker-Springett, K., Whitmarsh, L., Wood, R.; (2015) Towards
a culture of low-carbon research for
the 21st Century Tyndall Working Paper
161
• Wilson, C.; Crane, L.; Chryssochoidis, G.; (2014) Why do people decide to renovate their homes to improve energy efficiency? Tyndall Working Paper 160
• Baker, L.; Linnea Wlokas, H.; (2014)South Africa's Renewable Energy
Procurement: A New Frontier TyndallWorking Paper 159;
• Potten, D. (2013) The Green ClimateFund and Lessons from other GlobalFunds’ Experience Tyndall Working
Paper 158;
• Martin, M.; Thornley, P. (2013) The
potential for thermal storage toreduce the overall carbon emissionsfrom district heating systems Tyndall
Working Paper 157;
• Diaz-Rainey, I; Finegan, A; Ibikunle, G;
Tulloch, DJ; (2012) InstitutionalInvestment in the EU ETS TyndallWorking Paper 156;
• Kelly, S; Crawford-Brown, D; Pollitt, M.;(2012) Building Performance
evaluation and certification in the UK:Is SAP fit for purpose? Renewable andSustainable Energy Reviews Tyndall
Working Paper 155;
• Kelly, S.; Shipworth, M.; Shipworth, D.;
Gentry, M.; Wright, A.; Pollitt, M.;Crawford-Brown, D.; Lomas, K.; (2012) Apanel model for predicting the
diversity of internal temperatures
from English dwellings Tyndall Working Paper 154;
• Bellamy, R.; Chilvers, J.; Vaughan, NE.; Lenton, T M.; (2012) AppraisingGeoengineering Tyndall Working Paper
153;
• Nordhagen, S.; Calverley, D.; Foulds, C.;
Thom, L.; Wang, X.; (2012) Credibility inclimate change research: a reflexiveview Tyndall Working Paper 152;
• Milman, A.; Bunclark, L.; Conway, D.and Adger, W N (2012) Adaptive
Capacity of Transboundary Basins inthe Mediterranean, the Middle Eastand the Sahel Tyndall Working Paper
151;
• Upham, P.; Kuttapan, V., and Tomeic, J.
(2012) Sustainable livelihoods andcultivation of Jatropha curcas forbiodiesel in India: reflections on
alternative agronomic models TyndallWorking Paper 150;
• Shen, W.(2011) Understanding thedominance of unilateral CDMs inChina: Its origins and implications for
governing carbon markete TyndallWorking Paper 149;
• Mercure, JF.(2011) Global electricity
technology substitution model withinduced technological change Tyndall
Working Paper 148;• Gough, C., and Upham, P.(2010)Biomass energy with carbon capture
and storage (BECCS): a review TyndallWorking Paper 147;
• Kebede, A., Nicholls R. J., Hanson S.and Mokrech, M.(2010) Impacts ofClimate Change and Sea-Level Rise: A
Preliminary Case Study of Mombasa,Kenya. Tyndall Working Paper 146;
• Dendler, L.(2010) Sustainability MetaLabelling: A Discussion of Potential
Implementation Issues. Tyndall
Working Paper 145;
• McLachlan, C.(2010) Tidal stream
energy in the UK: Stakeholderperceptions study. Tyndall WorkingPaper 144;
• Upham, P., and Julia Tomei (2010)
Critical Stakeholder Perceptions ofCarbon and Sustainability Reporting inthe UK Renewable Transport Fuel
Obligation. Tyndall Centre Working Paper143;
• Hargreaves, T. (2010) The Visible
Energy Trial: Insights from QualitativeInterviews. Tyndall Working Paper 141;
• Newsham, A., and D. Thomas. (2009)Agricultural adaptation, localknowledge and livelihoods
diversification in North-CentralNamibia. Tyndall Working Paper 140;
• Starkey, R.. (2009) Assessingcommon(s) arguments for an equalper capita allocation. Tyndall Working
Paper 139;
• Bulkeley, H., and H. Schroeder. (2009)
Governing Climate Change Post-2012:The Role of Global Cities – Melbourne.Tyndall Working Paper 138;
• Seyfang, G., I. Lorenzoni, and M. Nye.,(2009) Personal Carbon Trading: a
critical examination of proposals forthe UK. Tyndall Working Paper 136.
• HTompkins E. L, Boyd E., Nicholson-ColeS, Weatherhead EK, Arnell N. W., AdgerW. N., (2009) An Inventory of
Adaptation to climate change in theUK: challenges and findings: TyndallWorking Paper 135;
• Haxeltine A., Seyfang G., (2009)Transitions for the People: Theory and
Practice of ‘Transition’ and‘Resilience’ in the UK’s TransitionMovement: Tyndall Working Paper 134;
• Tomei J., Upham P., (2009)Argentinean soy based biodiesel: anintroduction to production and
impacts: Tyndall Working Paper 133;
• Whitmarsh L, O'Neill S, Seyfang G.,Lorenzoni I., (2008) Carbon Capability:what does it mean, how prevalent is
it, and how can we promoteit?: Tyndall Working Paper 132;
• Huang Y., Barker T., (2009)Does Geography Matter for the CleanDevelopment Mechanism? :
Tyndall Working Paper 131;
• Huang Y., Barker T., (2009)
The Clean Development Mechanismand Sustainable Development: APanel Data Analysis: Tyndall Working
Paper 130;
• Dawson R., Hall J, Barr S, Batty M.,
Bristow A, Carney S, Dagoumas, A., EvansS., Ford A, Harwatt H., Kohler J., Tight M,
(2009) A blueprint for the integratedassessment of climate change incities: Tyndall Working Paper 129;
• Carney S, Whitmarsh L, Nicholson-ColeS, Shackley S., (2009) A Dynamic
Typology of Stakeholder Engagementwithin Climate Change Research:Tyndall Working paper 128;
• Goulden M, Conway D, Persechino A.,(2008) Adaptation to climate change in
international river basins in Africa: areview: Tyndall Working paper 127;
• Bows A., Anderson K., (2008)A bottom-up analysis of includingaviation within the EU’s Emissions
Trading Scheme: Tyndall Working Paper126;
• Al-Saleh Y., Upham P., Malik K., (2008)Renewable Energy Scenarios for theKingdom of Saudi Arabia: Tyndall
Working Paper 125
• Scrieciu S., Barker T., Smith V., (2008)
World economic dynamics andtechnological change: projectinginteractions between economic output
and CO2 emissions :Tyndall WorkingPaper 124
• Bulkeley H, Schroeder H., (2008)Governing Climate Change Post-2012:
The Role of Global Cities - London:Tyndall Working Paper 123• Schroeder H., Bulkeley H, (2008)
Governing Climate Change Post-2012:The Role of Global Cities, Case-Study:Los Angeles: Tyndall Working Paper 122
• Wang T., Watson J, (2008) CarbonEmissions Scenarios for China to
2100: Tyndall Working Paper 121
• Bergman, N., Whitmarsh L, Kohler J.,
(2008) Transition to sustainabledevelopment in the UK housingsector: from case study to model
implementation: Tyndall Working Paper120
• Conway D, Persechino A., Ardoin-BardinS., Hamandawana H., Dickson M, DieulinC, Mahe G, (2008) RAINFALL AND
WATER RESOURCES VARIABILITY INSUB-SAHARAN AFRICA DURING THE20TH CENTURY: Tyndall Centre Working
Paper 119
• Starkey R., (2008) Allocating
emissions rights: Are equal shares,fair shares? : Tyndall Working Paper 118
• Barker T., (2008) The Economics ofAvoiding Dangerous Climate Change:Tyndall Centre Working Paper 117
• Estrada M, Corbera E., Brown K, (2008)How do regulated and voluntary
carbon-offset schemes compare?:Tyndall Centre Working Paper 116
• Estrada Porrua M, Corbera E., Brown K,(2007) REDUCING GREENHOUSE GASEMISSIONS FROM DEFORESTATION
IN DEVELOPING COUNTRIES:
REVISITING THE ASSUMPTIONS:
Tyndall Centre Working Paper 115
• Boyd E., Hultman N E., Roberts T.,
Corbera E., Ebeling J., Liverman D, Brown K, Tippmann R., Cole J., Mann P, Kaiser M., Robbins M, (2007) The Clean
Development Mechanism: An assessment of current practice and future approaches for policy: Tyndall
Centre Working Paper 114
• Hanson, S., Nicholls, R., Balson, P.,
Brown, I., French, J.R., Spencer, T., Sutherland, W.J. (2007) Capturing coastal morphological
change within regional integrated assessment: an outcome-driven fuzzy logic approach: Tyndall Working Paper
No. 113
• Okereke, C., Bulkeley, H. (2007)
Conceptualizing climate change governance beyond the international regime: A review of four theoretical
approaches: Tyndall Working Paper No. 112
• Doulton, H., Brown, K. (2007) ‘Ten years to prevent catastrophe’? Discourses of climate change and
international development in the UK press: Tyndall Working Paper No. 111
• Dawson, R.J., et al (2007) Integrated analysis of risks of coastal flooding and cliff erosion under scenarios of
long term change: Tyndall Working Paper No. 110
• Okereke, C., (2007) A review of UK FTSE 100 climate strategy and a framework for more in-depth analysis
in the context of a post-2012 climate regime: Tyndall Centre Working Paper 109
• Gardiner S., Hanson S., Nicholls R., Zhang Z., Jude S., Jones A.P., et al (2007)
The Habitats Directive, Coastal Habitats and Climate Change – Case
Studies from the South Coast of the
UK: Tyndall Centre Working Paper 108
• Schipper E. Lisa, (2007) Climate
Change Adaptation and Development: Exploring the Linkages: Tyndall Centre Working Paper 107
• Okereke C., Mann P, Osbahr H, (2007) Assessment of key negotiating issues
at Nairobi climate COP/MOP and what it means for the future of the climate regime: Tyndall Centre Working Paper
No. 106
• Walkden M, Dickson M, (2006) The
response of soft rock shore profiles to increased sea-level rise. : Tyndall Centre Working Paper 105
• Dawson R., Hall J, Barr S, Batty M., Bristow A, Carney S, Evans E.P., Kohler J.,
Tight M, Walsh C, Ford A, (2007) A blueprint for the integrated assessment of climate change in
cities. : Tyndall Centre Working Paper 104
• Dickson M., Walkden M., Hall J., (2007) Modelling the impacts of climate change on an eroding coast over the
21st Century: Tyndall Centre Working Paper 103
• Klein R.J.T, Erickson S.E.H, Næss L.O,
Hammill A., Tanner T.M., Robledo, C., O’Brien K.L.,(2007) Portfolio screening
to support the mainstreaming of adaptation to climatic change into development assistance: Tyndall Centre
Working Paper 102
• Agnolucci P., (2007) Is it going to
happen? Regulatory Change and Renewable Electricity: Tyndall Centre Working Paper 101
• Kirk K., (2007) Potential for storage of carbon dioxide in the rocks beneath
the East Irish Sea: Tyndall Centre Working Paper 100
• Arnell N.W., (2006) Global impacts of
abrupt climate change: an initial
assessment: Tyndall Centre Working Paper 99
• Lowe T.,(2006) Is this climate porn? How does climate change communication affect our perceptions
and behaviour?, Tyndall Centre Working Paper 98
• Walkden M, Stansby P,(2006) The effect of dredging off Great Yarmouth on the wave conditions and erosion of
the North Norfolk coast. Tyndall Centre Working Paper 97
• Anthoff, D., Nicholls R., Tol R S J, Vafeidis, A., (2006) Global and regional
exposure to large rises in sea-level: a sensitivity analysis. This work was prepared for the Stern Review on the
Economics of Climate Change: Tyndall Centre Working Paper 96
• Few R., Brown K, Tompkins E. L, (2006) Public participation and climate change adaptation, Tyndall Centre
Working Paper 95 • Corbera E., Kosoy N, Martinez Tuna M,
(2006) Marketing ecosystem services through protected areas and rural communities in Meso-America:
Implications for economic efficiency, equity and political legitimacy, Tyndall Centre Working Paper 94
• Schipper E. Lisa, (2006) Climate Risk, Perceptions and Development in
El Salvador, Tyndall Centre Working Paper 93
• Tompkins E. L, Amundsen H, (2005) Perceptions of the effectiveness of the United Nations Framework Convention
on Climate Change in prompting behavioural change, Tyndall Centre Working Paper 92
• Warren R., Hope C, Mastrandrea M, Tol R S J, Adger W. N., Lorenzoni I., (2006)
Spotlighting the impacts functions in
integrated assessments. Research Report Prepared for the Stern Review on the Economics of Climate Change,
Tyndall Centre Working Paper 91 • Warren R., Arnell A, Nicholls R., Levy P
E, Price J, (2006) Understanding the regional impacts of climate change: Research Report Prepared for the
Stern Review on the Economics of Climate Change, Tyndall Centre Working Paper 90
• Barker T., Qureshi M, Kohler J., (2006)
The Costs of Greenhouse Gas Mitigation with Induced Technological Change: A Meta-Analysis of Estimates
in the Literature, Tyndall Centre Working Paper 89
• Kuang C, Stansby P, (2006) Sandbanks for coastal protection: implications of sea-level rise. Part 3:
wave modelling, Tyndall Centre Working Paper 88
• Kuang C, Stansby P, (2006) Sandbanks for coastal protection: implications of sea-level rise. Part 2:
current and morphological modelling, Tyndall Centre Working Paper 87
• Stansby P, Kuang C, Laurence D, Launder B, (2006) Sandbanks for coastal protection: implications of sea-level
rise. Part 1: application to East Anglia, Tyndall Centre Working Paper 86
• Bentham M, (2006) An assessment of carbon sequestration potential in
the UK – Southern North Sea case study: Tyndall Centre Working Paper 85
• Anderson K., Bows A., Upham P., (2006) Growth scenarios for EU & UK aviation: contradictions with climate
policy, Tyndall Centre Working Paper 84 • Williamson M., Lenton T., Shepherd J.,
Edwards N, (2006) An efficient
numerical terrestrial scheme (ENTS)
for fast earth system modelling, Tyndall Centre Working Paper 83
• Bows, A., and Anderson, K. (2005) An analysis of a post-Kyoto climate policy model, Tyndall Centre Working Paper 82
• Sorrell, S., (2005) The economics of energy service contracts, Tyndall Centre
Working Paper 81 • Wittneben, B., Haxeltine, A., Kjellen,
B., Köhler, J., Turnpenny, J., and Warren, R., (2005) A framework for assessing the political economy of post-2012
global climate regime, Tyndall Centre Working Paper 80
• Ingham, I., Ma, J., and Ulph, A. M. (2005) Can adaptation and mitigation be complements?, Tyndall Centre
Working Paper 79 • Agnolucci,. P (2005) Opportunism
and competition in the non-fossil fuel obligation market, Tyndall Centre Working Paper 78
• Barker, T., Pan, H., Köhler, J., Warren., R and Winne, S. (2005) Avoiding
dangerous climate change by inducing technological progress: scenarios using a large-scale econometric model,
Tyndall Centre Working Paper 77 • Agnolucci,. P (2005) The role of
political uncertainty in the Danish renewable energy market, Tyndall Centre Working Paper 76
• Fu, G., Hall, J. W. and Lawry, J.
(2005) Beyond probability: new methods for representing uncertainty in projections of future climate, Tyndall
Centre Working Paper 75 • Ingham, I., Ma, J., and Ulph, A. M.
(2005) How do the costs of adaptation affect optimal mitigation when there is uncertainty, irreversibility and
learning?, Tyndall Centre Working Paper
74 • Walkden, M. (2005) Coastal
process simulator scoping study, Tyndall Centre Working Paper 73
• Lowe, T., Brown, K., Suraje Dessai, S., Doria, M., Haynes, K. and Vincent., K (2005) Does tomorrow ever come?
Disaster narrative and public perceptions of climate change, Tyndall Centre Working Paper 72
• Boyd, E. Gutierrez, M. and Chang, M. (2005) Adapting small-scale CDM sinks
projects to low-income communities, Tyndall Centre Working Paper 71
• Abu-Sharkh, S., Li, R., Markvart, T., Ross, N., Wilson, P., Yao, R., Steemers, K., Kohler, J. and Arnold, R. (2005) Can
Migrogrids Make a Major Contribution to UK Energy Supply?, Tyndall Centre Working Paper 70
• Tompkins, E. L. and Hurlston, L. A. (2005) Natural hazards and climate
change: what knowledge is transferable?, Tyndall Centre Working Paper 69
• Bleda, M. and Shackley, S. (2005) The formation of belief in climate
change in business organisations: a dynamic simulation model, Tyndall Centre Working Paper 68
• Turnpenny, J., Haxeltine, A. and O’Riordan, T., (2005) Developing
regional and local scenarios for climate change mitigation and
adaptation: Part 2: Scenario creation, Tyndall Centre Working Paper 67
• Turnpenny, J., Haxeltine, A., Lorenzoni, I., O’Riordan, T., and Jones, M., (2005) Mapping actors involved in
climate change policy networks in the UK, Tyndall Centre Working Paper 66
• Adger, W. N., Brown, K. and
Tompkins, E. L. (2004) Why do resource managers make links to stakeholders at other scales?, Tyndall Centre Working
Paper 65 • Peters, M.D. and Powell, J.C. (2004)
Fuel Cells for a Sustainable Future II, Tyndall Centre Working Paper 64
• Few, R., Ahern, M., Matthies, F. and Kovats, S. (2004) Floods, health and climate change: a strategic review,
Tyndall Centre Working Paper 63 • Barker, T. (2004) Economic theory
and the transition to sustainability: a comparison of approaches, Tyndall Centre Working
Paper 62 • Brooks, N. (2004) Drought in the
African Sahel: long term perspectives and future prospects, Tyndall Centre Working Paper 61
• Few, R., Brown, K. and Tompkins, E.L. (2004) Scaling adaptation: climate
change response and coastal management in the UK, Tyndall Centre Working Paper 60
• Anderson, D and Winne, S. (2004) Modelling Innovation and Threshold
Effects In Climate Change Mitigation, Tyndall Centre Working Paper 59
• Bray, D and Shackley, S. (2004) The Social Simulation of The
Public Perceptions of Weather Events and their Effect upon the Development
of Belief in Anthropogenic Climate Change, Tyndall Centre Working Paper 58
• Shackley, S., Reiche, A. and Mander, S (2004) The Public Perceptions of Underground Coal Gasification (UCG):
A Pilot Study, Tyndall Centre Working Paper 57
• Vincent, K. (2004) Creating an
index of social vulnerability to climate change for Africa, Tyndall Centre Working Paper 56
• Mitchell, T.D. Carter, T.R., Jones,
.P.D, Hulme, M. and New, M. (2004) A comprehensive set of high-resolution grids of monthly climate for Europe
and the globe: the observed record (1901-2000) and 16 scenarios (2001-2100), Tyndall Centre Working Paper 55
• Turnpenny, J., Carney, S., Haxeltine, A., and O’Riordan, T. (2004)
Developing regional and local scenarios for climate change mitigation and adaptation Part 1: A
framing of the East of England Tyndall Centre Working Paper 54
• Agnolucci, P. and Ekins, P. (2004) The Announcement Effect And Environmental Taxation Tyndall Centre
Working Paper 53 • Agnolucci, P. (2004) Ex Post
Evaluations of CO2 –Based Taxes: A Survey Tyndall Centre Working Paper 52
• Agnolucci, P., Barker, T. and Ekins, P. (2004) Hysteresis and Energy Demand: the Announcement Effects
and the effects of the UK Climate Change Levy Tyndall Centre Working Paper 51
• Powell, J.C., Peters, M.D., Ruddell, A. and Halliday, J. (2004) Fuel Cells for a
Sustainable Future? Tyndall Centre Working Paper 50
• Awerbuch, S. (2004) Restructuring our electricity networks to promote
decarbonisation, Tyndall Centre Working Paper 49
• Pan, H. (2004) The evolution of economic structure under technological development, Tyndall
Centre Working Paper 48
• Berkhout, F., Hertin, J. and Gann, D. M., (2004) Learning to adapt: Organisational adaptation to climate
change impacts, Tyndall Centre Working Paper 47
• Watson, J., Tetteh, A., Dutton, G., Bristow, A., Kelly, C., Page, M. and Pridmore, A., (2004) UK Hydrogen
Futures to 2050, Tyndall Centre Working Paper 46
• Purdy, R and Macrory, R. (2004) Geological carbon sequestration: critical legal issues, Tyndall Centre
Working Paper 45
• Shackley, S., McLachlan, C. and Gough, C. (2004) The Public Perceptions of Carbon Capture and Storage, Tyndall
Centre Working Paper 44 • Anderson, D. and Winne, S. (2003)
Innovation and Threshold Effects in Technology Responses to Climate Change, Tyndall Centre Working Paper 43
• Kim, J. (2003) Sustainable Development and the CDM: A South
African Case Study, Tyndall Centre Working Paper 42
• Watson, J. (2003), UK Electricity Scenarios for 2050, Tyndall Centre Working Paper 41
• Klein, R.J.T., Lisa Schipper, E. and Dessai, S. (2003), Integrating
mitigation and adaptation into climate and development policy: three
research questions, Tyndall Centre Working Paper 40
• Tompkins, E. and Adger, W.N. (2003). Defining response capacity to enhance climate change policy, Tyndall
Centre Working Paper 39 • Brooks, N. (2003). Vulnerability,
risk and adaptation: a conceptual
framework, Tyndall Centre Working Paper
38 • Ingham, A. and Ulph, A. (2003)
Uncertainty, Irreversibility, Precaution and the Social Cost of Carbon, Tyndall Centre Working Paper 37
• Kröger, K. Fergusson, M. and Skinner, I. (2003). Critical Issues in
Decarbonising Transport: The Role of Technologies, Tyndall Centre Working Paper 36
• Tompkins E. L and Hurlston, L. (2003). Report to the Cayman Islands’
Government. Adaptation lessons learned from responding to tropical cyclones by the Cayman Islands’
Government, 1988 – 2002, Tyndall Centre Working Paper 35
• Dessai, S., Hulme, M (2003). Does climate policy need probabilities?, Tyndall Centre Working Paper 34
• Pridmore, A., Bristow, A.L., May, A. D. and Tight, M.R. (2003). Climate
Change, Impacts, Future Scenarios and the Role of Transport, Tyndall Centre Working Paper 33
• Xueguang Wu, Jenkins, N. and
Strbac, G. (2003). Integrating Renewables and CHP into the UK Electricity System: Investigation of the
impact of network faults on the stability of large offshore wind farms, Tyndall Centre Working Paper 32
• Turnpenny, J., Haxeltine A. and
O’Riordan, T. (2003). A scoping study of UK user needs for managing climate futures. Part 1 of the pilot-phase
interactive integrated assessment process (Aurion Project), Tyndall Centre Working Paper 31
• Hulme, M. (2003). Abrupt climate change: can society cope?, Tyndall
Centre Working Paper 30
• Brown, K. and Corbera, E. (2003). A Multi-Criteria Assessment Framework for Carbon-Mitigation Projects: Putting
“development” in the centre of decision-making, Tyndall Centre Working Paper 29
• Dessai, S., Adger, W.N., Hulme, M., Köhler, J.H., Turnpenny, J. and Warren, R.
(2003). Defining and experiencing dangerous climate change, Tyndall Centre Working Paper 28
• Tompkins, E.L. and Adger, W.N. (2003). Building resilience to climate
change through adaptive management of natural resources, Tyndall Centre Working Paper 27
• Brooks, N. and Adger W.N. (2003). Country level risk measures of climate-
related natural disasters and implications for adaptation to climate change, Tyndall Centre Working Paper 26
• Xueguang Wu, Mutale, J., Jenkins, N. and Strbac, G. (2003). An investigation
of Network Splitting for Fault Level Reduction, Tyndall Centre Working Paper 25
• Xueguang Wu, Jenkins, N. and Strbac, G. (2002). Impact of Integrating
Renewables and CHP into the UK Transmission Network, Tyndall Centre Working Paper 24
• Paavola, J. and Adger, W.N. (2002). Justice and adaptation to climate
change, Tyndall Centre Working Paper 23
• Watson, W.J., Hertin, J., Randall, T., Gough, C. (2002). Renewable Energy and Combined Heat and Power
Resources in the UK, Tyndall Centre Working Paper 22
• Watson, W. J. (2002). Renewables and CHP Deployment in the UK to 2020, Tyndall Centre Working Paper 21
• Turnpenny, J. (2002). Reviewing
organisational use of scenarios: Case study - evaluating UK energy policy options, Tyndall Centre Working Paper 20
• Pridmore, A. and Bristow, A., (2002). The role of hydrogen in powering road
transport, Tyndall Centre Working Paper 19
• Watson, J. (2002). The development of large technical systems: implications for hydrogen,
Tyndall Centre Working Paper 18 • Dutton, G., (2002). Hydrogen
Energy Technology, Tyndall Centre Working Paper 17
• Adger, W.N., Huq, S., Brown, K., Conway, D. and Hulme, M. (2002). Adaptation to climate change: Setting
the Agenda for Development Policy and Research, Tyndall Centre Working Paper 16
• Köhler, J.H., (2002). Long run technical change in an energy-
environment-economy (E3) model for an IA system: A model of Kondratiev waves, Tyndall Centre Working Paper 15
• Shackley, S. and Gough, C., (2002). The Use of Integrated Assessment: An
Institutional Analysis Perspective, Tyndall Centre Working Paper 14
• Dewick, P., Green K., Miozzo, M., (2002). Technological Change, Industry Structure and the Environment, Tyndall
Centre Working Paper 13
• Dessai, S., (2001). The climate regime from The Hague to Marrakech: Saving or sinking the Kyoto Protocol?,
Tyndall Centre Working Paper 12 • Barker, T. (2001). Representing
the Integrated Assessment of Climate Change, Adaptation and Mitigation, Tyndall Centre Working Paper 11
• Gough, C., Taylor, I. and Shackley, S.
(2001). Burying Carbon under the Sea: An Initial Exploration of Public Opinions, Tyndall Centre Working Paper
10 • Barnett, J. and Adger, W. N. (2001).
Climate Dangers and Atoll Countries, Tyndall Centre Working Paper 9
• Adger, W. N. (2001). Social Capital and Climate Change, Tyndall Centre Working Paper 8
• Barnett, J. (2001). Security and Climate Change, Tyndall Centre Working Paper 7
• Goodess, C.M., Hulme, M. and Osborn, T. (2001). The identification and
evaluation of suitable scenario development methods for the estimation of future probabilities of
extreme weather events, Tyndall Centre Working Paper 6
• Barnett, J. (2001). The issue of
'Adverse Effects and the Impacts of Response Measures' in the UNFCCC, Tyndall Centre Working Paper 5
• Barker, T. and Ekins, P. (2001). How High are the Costs of Kyoto for the US
Economy?, Tyndall Centre Working Paper 4
• Berkhout, F, Hertin, J. and Jordan, A. J. (2001). Socio-economic futures in climate change impact assessment:
using scenarios as 'learning machines', Tyndall Centre Working Paper 3
• Hulme, M. (2001). Integrated Assessment Models, Tyndall Centre Working Paper 2
• Mitchell, T. and Hulme, M. (2000). A Country-by-Country Analysis of Past
and Future Warming Rates, Tyndall Centre Working Paper 1
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