Post on 18-Jul-2020
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
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
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
Methane: Observed Concentrations Compared to IPCC Projections Slide from:
Methane- Global budget 2003-2012
Slide from:
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
Emission inventories
Slide from:Methane – Wetland methane emissions Source: Saunois et al. 2016, ESSD (Fig 3);
Biogeochemistry models & data-driven methods
• 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
Biogeochemistry models & data-driven methods
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
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 –Global methane emissions 2003-2012
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
Biogeochemistry models & data-driven methods
Emission inventories
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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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:
Biogeochemistry models & data-driven methods
Emission inventories
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
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
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 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 153Agriculture, 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
• 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
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
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 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 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)
• 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
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Ocean Data View & CO2SYS
CO2SYS – software / code for investigating marine carbonate system
http://odv.awi.de
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