Transcript Natural or Anthropogenic?

Intergovernmental Panel on
Climate Change (IPCC)
International Scientific Consensus
and Climate Model Projections
Outline

The IPCC as an organization
 What inputs do they use – review of some
global warming evidence
 How do they make models?
 What are the projections?
 Conclusion
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 widely
accepted scientific, technical and socio-economic information
available 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-related
data. Its mandate is to assess … peer-reviewed literature … to ensure
a balanced reporting of viewpoints…”
All quotes from “Introduction to the IPCC” - http://www.ipcc.ch
IPCC Organization
IPCC Chair
IPCC Bureau
WG I
Science
WG II
Impacts
WG III
Mitigation
Task Force
on GHG
IPCC 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 concentrating
on findings after 1995; looks at regional as well as global
effects
Fourth Assessment Report – Due in 2007
IPCC Process
Approximately 1000 experts directly involved in
drafting and revising the reports
About 2500 participate in the review process
IPCC authors are nominated by governments and
international organizations, and represent universities,
research centers, business and environmental groups
from 120 countries
IPCC Process
“...(T)eams of lead authors are assembled … Every
chapter team must represent a range of prevailing
scientific-technical viewpoints and expertise, and
ensure appropriate representation of experts from
developing and developed countries …”
Temperature Change Century
Temperature Change Millenium
Energy 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”
Natural or anthropogenic?
Model scenario indicators
Model projections
IPCC
model
scenarios
IPCC Projections
66%-90%
90%-99%
Carbon Budget
Carbon emissions and uptakes since 1800
(Gt C)
140
Land use
change
115
Oceans
110
265
Fossil
emissions
Terrestrial
180
Atmosphere
Watson, IPCC
2100
Natural CO2 changes
Petit et al, Nature v.399 (6735), pp. 429-436. (1999)
2100
Carbon Dioxide Concentration
400
today
350
250
200
150
100
50
0
400000
300000
200000
100000
Age (years before present)
0
CO2 (ppmv)
300
CO2 Concentrations
Methane Fluctuations
1500 ppbv
(today)
Petit et al, Nature v.399 (6735), pp. 429-436. (1999)
Methane concentrations
900
800
600
500
400
300
200
100
0
400000
300000
200000
100000
Age (years before present)
0
CH4 (ppbv)
700
Probability distributions
“Interpretation of High Projections for Global-Mean Warming” T.M.L. Wigley and S.C.B. Raper
20 JULY 2001 VOL 293 SCIENCE
Stop burning fossil fuels?
“The Climate Change Commitment” T. M. L. Wigley 18 MARCH 2005 VOL 307 SCIENCE
Keep burning at same rate?
“The Climate Change Commitment” T. M. L. Wigley 18 MARCH 2005 VOL 307 SCIENCE
Questions

Is the current evidence convincing
(especially for non-scientists)?
 Are models + scenarios convincing (as a
way to project to the future)?