New Projecting climate change impacts: how robust are our...

International Conference ADAPTtoCLIMATENicosia, Cyprus, 27-28 March 2014

Projecting climate change impacts: how robust are our methods?

Timothy CarterFinnish Environment Institute, SYKE


Outline

Introduction: why focus on impacts? Methods of projecting future impacts Investigating uncertainties Are impact models "fit for purpose"? Conclusions


Why focus on impacts?


Possible objectives

To assess:

• biophysical effects of climate change (magnitude and rate)

• economic costs of climate change (damages, benefits, effectiveness)

• socio-political and cultural effects of climate change

• integrated effects of climate change, including feedbacks

• the need for adaptation


The adaptation learning cycle

Source: PROVIA, 2013


Monday 31 March 2014, Yokohama

Release of the IPCC Working Group II Fifth Assessment Report (AR5):Climate Change 2014: Impacts, Adaptation, and Vulnerability


Methods of projecting future impacts


Generic assessment methods• Expert elicitation• Analogues

• Historical periods/trends• Past extreme events• Geographical analogues

• Controlled experiments• Indicator mapping• Impact modelling

• Empirical/statistical• Process-based• Site-scale through to global-scale• Single sector through multi-sector to fully integrated


Investigating uncertainties


Uncertainties in impact model projections

Model uncertainties Input data used for calibration

Parameter uncertainties (within-model)

Structural uncertainties (between model)

Projection uncertainties Model sensitivity/robustness

Scenario assumptions (climate and non-climate)

Scenario application (e.g. number; downscaling methods)


Scenarios for impact assessment

Scenarios of future climate, socioeconomic development, land use, other environmental factors

Earlier studies used IPCC scenarios (IS92 and SRES) New scenarios framework (RCPs/SSPs) developed

independent of IPCC


Source: van Vuuren et al., 2014

RCP/SSP scenario matrix architecture

RCP: Representative Concentration PathwaySSP: Shared Socioeconomic Pathway

RCP


Scenarios for impact assessment

Scenarios of climate, socioeconomic development, land use, other environmental factors

Earlier studies used IPCC scenarios (IS92 and SRES) New scenarios framework (RCPs/SSPs) developed

independent of IPCC Availability for impact assessment:

New access to AR5-assessed, CMIP5 climate data and scenarios from IPCC DDC

Basic (global) socioeconomic scenarios (ICONICS)

Mapping of new scenarios against SRES

Preliminary work on developing extended socioeconomic storylines and scenarios


Scenario application

Number of scenarios (e.g. representativeness) Probabilistic projections (risk assessment) Downscaling methods Representing changes in averages and variability Reference period for observations/projections


Uncertainties in impact model projections

Model uncertainties Input data used for calibration

Parameter uncertainties (within-model)

Structural uncertainties (between model)

Projection uncertainties Model sensitivity/robustness

Scenario assumptions (climate and non-climate)

Scenario application (e.g. number; downscaling methods)

Red cross: standard HadSM3 climate projection; default CATCHMOD versionLight blue curve: standard HadSM3 climate projection; 100 CATCHMOD versionsDark blue curve; default CATCHMOD version; 449 climate projectionsRed curve: all possible combinationsBlack curves: each climate projection; 100 CATCHMOD versionsGreen curves: each CATCHMOD version; 449 climate projections

Changes in median flow simulated with a hydrological model (CATCHMOD) when model parameter uncertainties are combined with the climateprediction.net (CP.net) ensemble of climate model projections

Source: New et al. (2007)


Simulated winter wheat yield from eight crop models (M1–M8), ensemble mean (Mean) and observed (Obs)

Model runs for eight sites in Europe

N = number of growing seasons with observed yields

Whiskers: min & max yields

Vertical dashed lines: observed min, median and max yields

Source: Palosuo et al. (2011)

Observed yields

Multi-model mean yields


Source: Schellnhuber et al., 2014

Assessing climate impacts across sectors

Inter-Sectoral Impact Model Intercomparison

Project (ISI–MIP)


Are impact models "fit for purpose"?


-2 0 2 4 6 8

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DE, S_wheat, 2008, ARMOSA

Temperature change (C)

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675

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825

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750 1500

2250

3000 3750

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75015002250300037504500525060006750750082509000975010500112501200012750135001425015000157501650017250180001875019500

Grain yield kg/haBaseline

Impact response surfaces

Source: Pirttioja et al. (in prep.)


Lleida, ES, Winter wheat, 30-year mean yield change (%) relative to unperturbed

Source: Pirttioja et al. (in prep.)

ANONYMOUS MODEL: Lleida, ES, Spring wheat, 30-year mean yield change (%) relative to unperturbed


Proposed co-ordinated cycle of model improvement and projection


PDFs: sampled uncertainties


Food per capita Water exploitation index

PDFs: sampled uncertainties


Summary: impact modelling Intercomparison studies are needed, but be cautious

of model convergence Scale issues (global versus regional/local) Sensitivity analysis – are models "fit for purpose"? Distinguish scenario analysis from uncertainty

analysis Treatment of adaptation – implicit or explicit? Ongoing work (e.g. HELIX, IMPRESSIONS, RISES-AM,

JPIs, COST)


Conclusions


Conclusions (1/2) Impact assessment is crucial for identifying

adaptation needs New initiatives on scenario development (e.g.

ICONICS, IPCC DDC) Ongoing work is applying impact model ensembles

and intercomparison


Conclusions (2/2)Some priority issues for future impact assessments include:

• Support for basic research and capacity building in model development and application

• Collection of empirical and experimental data to underpin model development

• Scenario development with stakeholders using the RCP/SSP framework at relevant scales

• Extension of model intercomparison exercises (sectors, scales, economic models)

• Full treatment of impact uncertainties• Improved treatment of impacts in integrated assessment models• Design and implementation of coordinated cycles of model


That's it


Notice

Colleagues are welcome to incorporate these slides into their own presentations, assuming they are correctly

acknowledged. However, the authors would also appreciate being informed prior to the extensive

use of this material in public meetings.

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