U.N. FCCC, Bracknell, 25-27 Sep 2002

Experts Meeting on Assessment of Contributions to Climate Change

Michael Prather

University of California at Irvine

Completeness & Assessment:What forcings are / should be included?

Validation:What are the minimum capabilities in simulating the current climate system?

E S S

What Greenhouse Agents are listed under Kyoto ?

Annex A

Carbon dioxide (CO2)

Methane (CH4)

Nitrous oxide (N2O)

Hydrofluorocarbons (HFCs)

Perfluorocarbons (PFCs)

Sulfur hexafluoride (SF6)

What are not ?

CFCs & HCFCs (Montreal - OK)

Sulfate Aerosols

Black & Organic Carbon Aerosols

Tropospheric Ozone (O3)

Carbon monoxide (CO)

Nitrogen Oxides (NOX)

What about indirect greenhouse gasesunder Kyoto ?

What Greenhouse Agents are forcing climate ?

Which Greenhouse Agents have a good historical record ?

CO2

CH4

N2O

CFCs

solar

strat O3

trop O3

sulfate

fossil fuel OC/BC

biomass OC/BC

mineral dust

aerosol indirect land use /albedo

Which Greenhouse Agents are attributable ?

Anthropogenic control of the old GHGases

CH4 emissions (600 Tg-CH4/yr)

fossil fuels17%

biomass burning 5%

landfills 7%

ruminants14%

rice 9%

pollution (lifetime) ??%

N2O emissions (16 Tg-N/yr)

industrial processes 7%

biomass burning 3%

agriculture24%

cattle/feedlots 12%CFC & HCFC emissions (<< 1 Tg/yr)

refrigeration, foam, propellant, cleaning

phased out under Montreal Protocol

Anthropogenic control of the new GHGases

PFCs = CF4 + ... (13 Gg/yr ++)

anthropogenic***100%

aluminum, industrial

SF6 emissions (6 Gg/yr ++)

anthropogenic 100%

insulation, electrical switches

HFC emissions (100 Gg/yr ++)

anthropogenic 100%

CFC partial replacements

Anthropogenic control of Aerosols

sulfate = SO2 emissions (110 Tg-S/yr)

fossil fuels 67%

biomass burning 2%

Black Carbon emissions (12 Tg/yr)

fossil fuels 55%

biomass burning 45%

Carbonaceous emissions (140 Tg/yr)

fossil fuels 20%

biomass burning 39%

Anthropogenic control of the pollution gases

CO emissions (2800 Tg-CO/yr)

fossil & domestic fuel 32%

biomass burning 25%

NOX emissions (52 Tg-N/yr)

fossil fuels 65%

biomass burning 14%

agriculture/soils 12%

VOC emissions (600 Tg-C/yr)

fossil fuel 28%

biomass burning 6%

CH4

CO is an indirect greenhouse gas

CO emissions are effectively

equivalent to CH4 emissions:

100 Tg-CO = 5 Tg-CH4(IPCC, TAR)

OHCO O3

Anthropogenic Impact through Reactive Pollutants1750 - 2000

18002000 O3 OH

CH4 +4.6 DU - 30 %

NOX +4.1 + 14

CO +1.2 - 11

VOC +0.5 - 5

sum +10 DU - 32 %

“observed” +9 (±4) ??

Effective Reactive Pollutant contribution to CH4

CH4 320 Tg(CH4)/y = direct emission

NOx 40 Tg(N)/y - 80 Tg(CH4)/y

CO 1000 Tg/y + 50 Tg(CH4)/y

VOC 250 Tg/y + 30 Tg(CH4)/y

Validation of key components from the historical record is essential for credibility.

Why do this just to get relative impacts?

If the historical record in poorly reproduced, then the ‘model’ is in error or is missing key components of climate change this challenges the accuracy of even the relative national impacts and makes the process likely to fail an IPCC review

What does this validation test?

Both models and emissions

Validation of key components from the historical record is essential for credibility.

What is the minimal set of historical climate parameters that (i) should be reproducible by simple models and (ii) provides critical tests of the climate change to date.

FORCING

CO2 record, CH4 record, aerosols ???

RESPONSE

surface T (NH vs. SH ?), ocean Heat Content ?

sea level rise

CO2 (ppm) - Battle/Etheridge

290

310

330

350

370

1880 1900 1920 1940 1960 1980 2000

CH4 (ppb) - Battle/Etheridg

800

900

1000

1100

1200

1300

1400

1500

1600

1700

1800

1880 1900 1920 1940 1960 1980 2000

mean CO2 & CH4

1880 – 2000

Surface Temperature

1860 – 2000

? NH – SH

shows effect of aerosols

Ocean Heat Content (upper 300 m)

1945 – 2000

Sea Level Rise

1800 – 2000

Validation of key components from the historical record is essential for credibility.

What combination of historical data does it take to demonstrate that the “relative attribution” calculation is valid & without systematic errors ?

total “attributable” forcing

(missing sources)

correct chemistry/carbon model

(affects time-weighting of emissions)

correct indirect forcing

correct climate sensitivity

(affects time-weighting of forcing)