Intergovernmental Panel on Intergovernmental Panel on Climate Change (IPCC)Climate Change (IPCC)

International Scientific Consensus and Climate Model Projections

OutlineOutline

The IPCC as an organizationWhat inputs do they use – review of some

global warming evidenceHow do they make models?What are the projections?Conclusion

IPCC - Why was it created?IPCC - Why was it created?“Human activities now occur on a scale that is starting to interfere with complex natural systems”“Climate change poses a serious challenge to policymakers”“Policymakers … need an objective source of the most widelyaccepted scientific, technical and socio-economic informationavailable about climate change”

“The World Meteorological Organization (WMO) and the UN Environment Programme (UNEP) established the IPCC in 1988. The Panel does not conduct new research or monitor climate-relateddata. Its mandate is to assess … peer-reviewed literature … to ensurea balanced reporting of viewpoints…”

All quotes from “Introduction to the IPCC” - http://www.ipcc.ch

IPCC OrganizationIPCC Organization

WG IScience

WG IIImpacts

WG IIIMitigation

Task Force on GHG

IPCC Bureau

IPCC Chair

IPCC ReportsIPCC Reports

First Assessment Report (1990) - Helped lead to work at Rio de Janeiro Earth Summit (1992) and UNFCCC

Second Assessment Report (1996) - Contributed to negotiations that lead to Kyoto Protocol (1997)

Third Assessment Report (2001) - Update concentratingon findings after 1995; looks at regional as well as globaleffects

Fourth Assessment Report – Due in 2007

IPCC ProcessIPCC Process

Approximately 1000 experts directly involved indrafting and revising the reports

About 2500 participate in the review process

IPCC authors are nominated by governments andinternational organizations, and represent universities,research centers, business and environmental groups from 120 countries

IPCC ProcessIPCC Process

“...(T)eams of lead authors are assembled … Every chapter team must represent a range of prevailingscientific-technical viewpoints and expertise, and ensure appropriate representation of experts from developing and developed countries …”

Temperature Change - Temperature Change - CenturyCentury

Temperature Change - Temperature Change - MilleniumMillenium

Energy BalanceEnergy Balance

“Earth’s Energy Imbalance: Confirmation and Implications” James Hansen, et al.Science 3 June 2005 308: 1431-1435 – Current imbalance of 0.85±0.15 W/m2

Model “Forcings”Model “Forcings”

Natural or anthropogenic?Natural or anthropogenic?

Model scenario indicatorsModel scenario indicators

Model projectionsModel projections

IPCCIPCCmodel model scenariosscenarios

IPCC ProjectionsIPCC Projections

66%-90%

90%-99%

Carbon BudgetCarbon Budget

C a rb o n e m is s io n s a n d u p ta k e s s in c e 1 8 0 0 (G t C )

1 8 0

1 1 0

1 1 5

2 65

14 0L a nd u se

ch an g e

F o ss il e m issio n s

At mo s p h er e

O ce a n s

T e r r e str ial

Watson, IPCC

Natural CONatural CO22 changes changes

Carbon Dioxide Concentration

0

50

100

150

200

250

300

350

400

0100000200000300000400000

Age (years before present)

CO

2 (p

pm

v)

2100

Petit et al, Nature v.399 (6735), pp. 429-436. (1999) 2100

today

COCO22 Concentrations Concentrations

Methane FluctuationsMethane FluctuationsPetit et al, Nature v.399 (6735), pp. 429-436. (1999)

1500 ppbv(today)

Methane concentrations

0

100

200

300

400

500

600

700

800

900

0100000200000300000400000

Age (years before present)

CH

4 (

pp

bv

)

Probability distributionsProbability distributions

“Interpretation of High Projections for Global-Mean Warming” T.M.L. Wigley and S.C.B. Raper20 JULY 2001 VOL 293 SCIENCE

Stop burning fossil fuels?Stop burning fossil fuels?

“The Climate Change Commitment” T. M. L. Wigley 18 MARCH 2005 VOL 307 SCIENCE

Keep burning at same rate?Keep burning at same rate?

“The Climate Change Commitment” T. M. L. Wigley 18 MARCH 2005 VOL 307 SCIENCE

QuestionsQuestions

Is the current evidence convincing (especially for non-scientists)?

Are models + scenarios convincing (as a way to project to the future)?