Workshop on Analytical Methods in Aquatic...

1ST-12TH OCTOBER 2018

National Oceanography Centre, Southampton, UK

Workshop on Analytical Methods in Aquatic Biogeochemistry

Greenhouse Gases

The greenhouse effect

1. Solar radiation passes through the clear atmosphere

2. Most radiation is absorbed by the Earth’s surface, warming it.

3. Infrared radiation is emitted from the Earth’s surface

5. Some is absorbed and re-emitted by GHG molecules. The effect of this is to warm the Earth’s surface and lower atmosphere.

6.The greater the number of GHG molecules, the greater the warming4. Some of the infrared

radiation passes through the atmosphere

The most abundant greenhouse gases are, in order of relative abundance:

• Water (H2O) Contribution: ~36 - 72%• Carbon dioxide (CO2) ~ 9 - 26%• Methane (CH4) ~ 4 - 9%• Nitrous oxide (N2O• Chlorofluorocarbons (CFCs)• Hydrofluorocarbons (incl. HCFCs and HFCs)

Gas Contribution Radiative forcing (W m-

2) (2016)

Lifetime (years)

GWP20yr

GWP 100yr

GWP500yr

Sources

Water ~36-72%

Carbon dioxide ~9-26% 1.985 30-95 1 1 1 Fossil fuels,

deforestation

Methane ~4-9% 0.507 8 84 28 7.6 Agriculture, fuel leakage

Nitrous oxide ~3-7% 0.193 121 264 265 153 Agriculture, fuel combustion

CFC-12 ~2-5% 0.164 100 10800 10200 5200 Refrigerants, propellants

15-minor(inc SF6) 0.121 500-50000 5000-17000 1700-23000 500-32000

CO2 dominates total forcing. Five major GHGs account for ~96% of total. In 2016, when combined, equivalent CO2 atmospheric

concentration = 489 (403)

Not just GHGs causing radiative forcing, but they are by far the largest contributor

- Oceans contain ~75% of all global C- Oceans absorb ~25% of all human-

derived CO2 being added to the atmosphere

Carbon dioxide

Three principal greenhouse gases – the ocean acts as a key reservoir, source or sink for all three.

Nitrous Oxide

Atmospheric increase since preindustrial era: N2O = 20%; CH4 = 150%; CO2 = 40%

Global Warming potential (over 20 years): N2O = 260; CH4 = ~80; CO2 = 1

Background Theme 1.2 Ocean Carbon and Control Over Greenhouse Gases (GHG)

- Oceans contain ~75% of global CH4 (principally in form of ocean hydrates)

- Source of ~4% of global emissions

- Oceans are source of ~30% of global emissions to atmosphere

Methane


2) (2016)

Lifetime (years)

GWP20yr

GWP 100yr

GWP500yr

Sources

Water ~36-72%


deforestation




15-minor(inc SF6) 0.121 500-50000 5000-17000 1700-23000 500-32000

Gas Contribution Radiative

forcing (W m-

2) (2016)

Lifetime

(years)

GWP

20yr

GWP

100yr

GWP

500yr

Sources

Water ~36-72%

Carbon dioxide

~9-26% 1.985 30-95 1 1 1Fossil fuels,

deforestation

Methane ~4-9% 0.507 8 84 28 7.6Agriculture, fuel

leakage

Nitrous oxide ~3-7% 0.193 121 264 265 153Agriculture, fuel

combustion

CFC-12 ~2-5% 0.164 100 10800 10200 5200Refrigerants, propellants

15-minor(inc SF6)

0.121 500-50000 5000-17000 1700-23000 500-32000

• After carbon dioxide (CO2), methane (CH4) is the second most important greenhouse gas contributing to human-induced climate change.

• For a time horizon of 100 years, CH4 has a Global Warming Potential 28 times larger than CO2.

• Methane is responsible for 20% of the global warming produced by all greenhouse gases so far.

• The concentration of CH4 in the atmosphere is 150% above pre-industrial levels (cf. 1750).

• The atmospheric life time of CH4 is 9±2 years, making it a good target for climate change mitigation

• Methane also contributes to tropospheric production of ozone, a pollutant that harms human health and ecosystems.

Sources : Saunois et al. 2016, ESDD; Kirschke et al. 2013, NatureGeo.; IPCC 2013 5AR; Voulgarakis et al., 2013

Slide from:Methane - context

Updated to 2012

• Methane also leads to production of water vapor in the stratosphere by chemical reactions, enhancing global warming.

Methane – modern concentrations unprecedented

Top-down budget

Ground-based data from observation networks (AGAGE, CSIRO, NOAA, UCI, LSCE, others).Satellite data (GOSAT, SCIAMACHY)

Agriculture and waste related

emissions, fossil fuel emissions (EDGARv4.2,

USEPA, GAINS, FAO).

Fire emissions (GFED3 & 4s,

FINN, GFAS, FAO).Biofuel estimates

Ensemble of 11 wetland models, following the WETCHIMP intercomparison

Model for Termites emissions

Other sources from literature

Suite of eight atmospheric inv. models (TM5-4DVAR (JRC & SRON), LMDZ-MIOP, PYVAR-LMDz, C-Tracker-CH4, GELCA, ACTM, TM3, NIESTM).Ensemble of 30 inversions (diff. obs & setup)

From Kirschke et al., (2013) Long-term trends and decadal variability of the OH sink.ACCMIP CTMs intercomparison.Soil uptake & chlorine sink taken from the literature

Atmospheric observations

Methane sinks Inverse models Biogeochemistry models & data-driven methods

Bottom-up budgetMethane - An ensemble of tools and data to estimate the global methane budget

Emission inventories

Slide from:

Slide from:

Source: Saunois et al. 2016, ESSD (Fig. 1)

• Slowdown of atmospheric growthrate before 2006

• Resumed increaseafter 2006

CH4$(pp

b)$

G ATM$(p

pb$yr/1)$

$

2000-2006: 0.6±0.1 ppb/yr

2007-2012: 5.5±0.6 ppb/yr

Methane - CH4 Atmospheric Growth Rate, 1983-2012

Atmospheric observations

Atmospheric concentrations (top plot): • Methane concentrations rose even faster in

2014 and 2015, more than 10 ppb/yr.

• The recent atmospheric increase is approaching

the RCP8.5 scenario

Anthropogenic emissions (bottom plot): • EDGARv4.2 infers an increase in emissions that

is roughly twice as fast as EPA and GAINS-

ECLIPSE5a before 2010

• Bottom-up inventories are higher than any RCPs

scenarios, except RCP8.5

Methane: Anthropogenic Methane Emissions & RCPs

Source: based on Saunois et al. 2016, ERL; Meinshausen et al., 2011

2005 2008 2011 2014 2017 2020

1750

1800

1850

1900

CH

4 co

ncen

tratio

ns (p

pb) RCP 8.5

RCP 6

RCP 4.5

RCP 2.5

Obs.

2005 2008 2011 2014 2017 2020Years

280

300

320

340

360

380

400

CH

4 em

issi

ons

(Tg

CH

4.yr-1

)

RCP 8.5

RCP 6

RCP 4.5

RCP 2.5

USEPAEDGARv42FT2012GAINS-ECLIPSE5a

2005 2008 2011 2014 2017 2020

370

380

390

400

410

420

CO

2 co

ncen

tratio

ns (p

pm)

2005 2008 2011 2014 2017 2020Years

7

8

9

10

11

12

CO

2 em

issi

ons

(Gt C

.yr-1

) EDGARv42FT2012CDIAC Boden et al., 2015

2005 2008 2011 2014 2017 2020

1750

1800

1850

1900

CH

4 co

ncen

tratio

ns (p

pb) RCP 8.5

RCP 6

RCP 4.5

RCP 2.5

Obs.

2005 2008 2011 2014 2017 2020Years

280

300

320

340

360

380

400

CH

4 em

issi

ons

(Tg

CH

4.yr-1

)

RCP 8.5

RCP 6

RCP 4.5

RCP 2.5

USEPAEDGARv42FT2012GAINS-ECLIPSE5a

2005 2008 2011 2014 2017 2020

370

380

390

400

410

420

CO

2 co

ncen

tratio

ns (p

pm)

2005 2008 2011 2014 2017 2020Years

7

8

9

10

11

12

CO

2 em

issi

ons

(Gt C

.yr-1

) EDGARv42FT2012CDIAC Boden et al., 2015

Slide from:

Atmospheric

observationsEmission

inventories

http://cdiac.ornl.gov/trends/emis/meth_reg.html

Methane: Observed Concentrations Compared to IPCC Projections Slide from:

Methane- Global budget 2003-2012

Slide from:

http://www.globalcarbonatlas.org

http://www.globalcarbonatlas.org

Slide from:Methane - Mapping of the largest methane source categories

Source: Saunois et al. 2016, ESSD (Fig 3);

Biogeochemistry models & data-driven methods


Slide from:Methane – Wetland methane emissions Source: Saunois et al. 2016, ESSD (Fig 3);


• Wetlands are the largest natural global CH4 source

• Emission from an ensemble carbon-cycle models constrained with remote sensing surface water andinventory-based wetland area data.

• The resulting global flux range for natural wetland emissions is 153–227 TgCH4/yr for the decade of2003–2012, with an average of 185 TgCH4/yr.

Methane – Mapping other natural sources

Termites

0.0

0.5

1.0

2.0

5.0

10.0

12.0

15.0

20.0

30.0

40.0

10-3

mg(CH4).m-2.day-1

(a)$

(b)$(a)Geological reservoirs

based on a data-driven method Termites

based on a process-based model

Other natural sources not mapped here are freshwater emissions, permafrost and hydrates


Source: Saunois et al. 2016 (Fig 4); Etiope (2015), Kirschke et al., 2013)

Slide from:

Methane – sinks (2000s)

Tropospheric OH

450-620 Tg/yr

Stratospheric chemistry

15-85 Tg/yr

Tropospheric chlorine

15-40 Tg/yrSoil uptake10-45 Tg/yr

Methane sinks

Source : Kirschke et al. 2013

Slide from:

Slide from:

Fresh waters 122 [100%]Wild animals 10 [100%]

Wild fires 3 [100%]Termites 9 [120%]

Geological 40 [50%]Oceans 3 [100%]

Permafrost 1 [100%]

ç Natural wetlands è

çOther natural emissionsè

çBiomass/biofuel burningè

ç Fossil fuel use è

ç Agriculture & waste è

167 [80%]185 [40%]

Atmospheric inversions

559 TgCH4/yr [540-568]

Process models, inventories, data driven methods

734 TgCH4/yr [596-884]

Mean [min-max range %]

64 [150%]199 [90%]

34 [55%]30 [30%]

105 [50%]121 [20%]

188 [65%]195 [15%]

Coal 42 [80%]Gas & oil 79 [10%]

Rice 30 [10%]Enteric ferm & manure 106 [20%]

Landfills & waste 59 [20%]

Source : Saunois et al. 2016, ESSD

Top-down budgetBottom-up budget

Bottom-up budgetTop-down budget

(TgCH4/yr)

Mean [uncertainty=min-max range %]

Mean [uncertainty=min-max range %]

Methane –Global methane emissions 2003-2012


• Global emissions:

559 TgCH4/yr [540-568] for TD

734 TgCH4/yr [596-884] for BU

• TD and BU estimates generally agree for

wetland and agricultural emissions

• Estimated fossil fuel emissions are lower for TD

than for BU approaches

• Large discrepancy between TD and BU

estimates for freshwaters and natural

geological sources (“other natural sources”)

Biogeochemistry models

& data-driven methods

Emission

inventories

Slide from:

Source: Saunois et al. 2016, ESSD (Fig 5)

Inverse models

Methane – Regional methane sources (2003-2012) Slide from:

Source: Saunois et al. 2016 ERL (Fig 2)

• 60% of global methane emissions come from tropical sources

• Anthropogenicsources are responsible for 60% of global emissions.

Inverse models



Inverse models

Methane – An interactive view of the methane budget

Top-down budget Bottom-up budgetSource: Saunois et al. 2016 ESSD; Dataviz group of LSCE

LINK : http://lsce-datavisgroup.github.io/MethaneBudget/

Slide from:

Methane – Regional methane sources (2003-2012)

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30

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60

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Tg#yr&1# Tg#yr&1# Tg#yr&1# Tg#yr&1#

Tg#yr&1#

Tg#yr&1# Tg#yr&1# Tg#yr&1# Tg#yr&1#

Tg#yr&1#

Tg#yr&1#

Tg#yr&1#

Tg#yr&1#

Tg#yr&1#

Northern#Africa# Southern#Africa# Oceania#

South&East#Asia#

India#

China#

Central#Eurasia##&#Japan#

Russia#Europe#Boreal#North#America#ConBguous#America#

Central##North#America#

Tropical#South#America#

Temperate#South#America#

Source: Saunois et al. 2016 ESSD (Fig 7)

• Largest emissions in Tropical South America, South-East Asia and China (50% of global emissions)

• Dominance of wetlandemissions in the tropics and borealregions

• Dominance of agriculture & waste in India and China

• Balance betweenagriculture & wasteand fossil fuels at mid-latitudes

• Uncertainmagnitude of wetlandemissions in boreal regionsbetween TD and BU

• Chineseemissions lowerin TD than in BU, African emissionslarger in TD thanin BU

Slide from:



Inverse models

Methane – Sink changes – impact of OH? Slide from:

Source : Dalsoren et al., 2016

• Sustained OH increase can contribute to explain the the stagnation of atmospheric methane (before 2007)

• Stagnation or decrease in OH radicals can contribute to explain : § the renewed increase of

atmospheric methane since 2007

§ The lighter atmosphere in 13C isotope since 2007

Key point: OH changes could have limited the emission changes necessary to explain the atmospheric methane variations

Methane – Sink changes – an accelerated atmospheric increase since 2014 Slide from:

1830 ppb reached in 2015

+12.5 ppb/yr in 2014

+10.0 ppb/yr in 2015

Challenging signal to analyse

Courtesy, Ed Dlugokencky, NOAA

Oceanic Methane – current status

Atlantic AMT transects show continued systematic CH4oversaturation

AMT-12 2003 Forster et al (2009) DSRII

AMT-7 1998

Rhee et al (2009) JGRA

Oceanic Methane – into the future

Bacterial degradation of dissolved organic matter found to produce methane

Repeta et al (2016) Nature Geosciences

Effect of warming oceans, deoxygenation, surface nutrient supply on DOM production (and subsequently CH4) under debate

Oceanic Methane – into the future – methane hydrates

• Exist as ice-like solid made of methane and water molecules• Stable under high pressures and low temperatures• Found in deep waters on continental margins and slopes• Hydrates lock methane in place beneath the sea floor• But susceptible to destabilization leading to methane release

Oceanic Methane – into the future – methane hydrates• Evidence for methane (and natural CO2) gas escape at the

sea floor is found on the continental margins around the world, including shelf seas

• Enormous potential reserves, therefore very important for future climate change predictions

• Some models suggest that significant volumes of methane could be released into the water column as seafloor hydrates dissociate in rapidly warming polar regions over the next 100 years

• Methane release from the seafloor will mostly dissolve in the water column (affecting ocean acidification)

• Methane released in shallow seas however, will mostly reach the atmosphere

Oceanic Methane – into the future – methane hydrates• Recent research has found seafloor warming

of 1°C in last 30 years. Some evidence for possible seafloor methane hydrate dissociation (melting) and release of methane gas into water column

‘Plumes’ of bubbles of suspected gas leakage

Magen et al (2017) LiOM

Seawater Methane – how to analyse


2) (2016)

Lifetime (years)

GWP20yr

GWP 100yr

GWP500yr

Sources

Water ~36-72%


deforestation




15-minor(inc SF6) 0.121 500-50000 5000-17000 1700-23000 500-32000


forcing (W m-

2) (2016)

Lifetime

(years)

GWP

20yr

GWP

100yr

GWP

500yr

Sources

Water ~36-72%


deforestation


Nitrous oxide ~3-7% 0.193 121 264 265 153Agriculture, fuel

combustion


15-minor(inc SF6) 0.121 500-50000 5000-17000 1700-23000 500-32000

• Atmospheric increase since preindustrial era = 20%;

• Global Warming potential (over 20 years) = 260;

• Responsible for 6% of the total global anthropogenic radiative forcing

• Largest source of stratospheric NOx (ozone hole)

• ~77% is produced by microorganisms (nitrification/denitrification)

Nitrous oxide

The atmospheric increase of N2O is largely attributed to agricultural activity

Nitrous oxide – Global Sources

IPCC 2006

1. Nitrogen fixed by lightning (falls in rain) and nitrogen fixing bacteria in legumes

2. Nitrogen-based fertilisers applied to pasture or crops3. Nitrogen taken up by pasture, crops or trees4. Nitrous oxide released through volatilisation of urea

fertilizer5. Nitrous oxide released through process of denitrification6. Nitrogen loss through runoff and leaching from fertilisers

and nitrification process in soil

Nitrous oxide is mainly released through soil disturbance, nitrogen fertilisers, urine and dung.

Nitrous oxide – Agricultural Sources

0

5

10

15

20

25

30

NAEI 2009 'Agricultural sources'

Gg N

2O

Nitrous oxide

UK sources of N2O

AMT-12 2003

Nitrous oxide –current status

Atlantic AMT transects show continued systematic N2O oversaturation

Forster et al (2009) DSRII

AMT-7 1998

Rhee et al (2009) JGRA

pH

Rees et al (2016) DSRII

Future change unclear:

- However, warming, increased stratification and changing biological patterns may increase hypoxia, and by extension N2O production

Codispoti (2010) Science

Nitrous oxide

- Increased acidification linked to decreased N2O production

Magen et al (2017) LiOM

Seawater Nitrous oxide – how to analyse

Or HgCl2


2) (2016)

Lifetime (years)

GWP20yr

GWP 100yr

GWP500yr

Sources

Water ~36-72%


deforestation




15-minor(inc SF6) 0.121 500-50000 5000-17000 1700-23000 500-32000


forcing (W m-

2) (2016)

Lifetime

(years)

GWP

20yr

GWP

100yr

GWP

500yr

Sources

Water ~36-72%


deforestation



CFC-12 ~2-5% 0.164 100 10800 10200 5200Refrigerants,

propellants

15-minor(inc SF6) 0.121 500-50000 5000-17000 1700-23000 500-32000

• Entirely anthropogenic

• Global Warming potential (over 20 years) = 5000-17000

• Responsible for 2-8% of the total global anthropogenic radiative forcing

• Widely used as refrigerants, propellants (in aerosol applications), and solvents

• Usage was banned as part of Montreal Protocol in 1987, in effort to curb the destruction of the Earth’s ozone hole rather than their greenhouse nature

Chlorofluorocarbons (CFCs)

• Entirely anthropogenic

• Global Warming potential (over 20 years) = 5000-17000

• Responsible for 2-8% of the total

global anthropogenic radiative forcing

• Widely used as refrigerants,

propellants (in aerosol applications),

and solvents

• Usage was banned as part of

Montreal Protocol in 1987, in effort to

curb the destruction of the Earth’s

ozone hole rather than their

greenhouse nature

Chlorofluorocarbons (CFCs)

SF6 still increasing

- Used predominantly

in electrical industry.

- Other main uses

include an inert

gas for the casting

of magnesium, and

as an inert filling

for insulated

glazing windows.

- [Also used to be

used to fill tennis

balls and Nike ‘Air’

Shoes

N. Atlantic Southern Ocean

(Open University) (Orsi et al., 1999)1984-1996

Chlorofluorocarbons (CFCs) – useful tracer of ocean circulation

Chlorofluorocarbons (CFCs) – useful tracer of ocean circulation

Chlorofluorocarbons (CFCs) – seawater analysis

1

3

4

2 2 3

5

5

1

2

34

5

5

SF6 can be analysed down to 10-17 mol kg-1CFCs can be analysed down to 10-15 mol kg-1

Carbon dioxide!

38,0004000

2300

7500

https://www.nodc.noaa.gov/ocads/oceans/CO2SYS/co2rprt.html

Ocean Data View & CO2SYS

CO2SYS – software / code for investigating marine carbonate system

http://odv.awi.de

Ocean Data ViewSoftware for viewing oceanographic data and calculating carbonate system

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