jth 17-07-2001 1 cop6bis/sbsta briefing on wgi contribution bonn: tuesday 17 july 2001 the...

JTH 17-07-2001 1 COP6bis/SBSTA

Briefing on WGI contribution

Bonn: Tuesday 17 July 2001

The Scientific Basis

Sir John Houghton Overview of WGI findings, observations, radiative forcing

Dr John Mitchell Model evaluation, detection and attribution

Dr Bob Watson The carbon cycle

Dr Ulrich Cubasch Climate projections (including regional projections and sea level)

IPCC Third Assessment Report (TAR)

Climate Change 2001: The Scientific Basis


IPCC Website

http://www.ipcc.ch


Structure of IPCC 1997 2001

WMO United Nations

UNEP COP/FCCC

Subsidiary bodies of the

framework convention on climate change

World Climate Programme

IGBP

Global Climate Observing system etc

IPCC

IPCCBureau

WGIScience

WGIIImpacts andadaptation

WGIIIMitigation

Lead Authors, Contributors, Reviewers


Climate Change 2001: The Scientific BasisWGI contribution to IPCC Third Assessment Report

Summary for Policymakers (SPM)

Drafted by a team of 59

Approved ‘sentence by sentence’

by WGI plenary (99 Governments and 45 scientists)

14 chapters

881 pages

120 Lead Authors

515 Contributing Authors

4621 References quoted


Key steps in preparation of Working Group I (science) component of Third Assessment Report

WORKING GROUP I SESSION

LEAD AUTHORS MEETING

TS / SPM

DRAFTING

INFORMAL REVIEW

EXPERT REVIEW

GOVERNMENT REVIEW

1998 1999 2000 2001

Bad MunsteriefelScoping Meeting

Vienna

VII

1

Paris

2

Arusha

3

Auckland

4

Victoria Shanghai

NewYork

Shanghai

VIII

5


What is global warming about ?


SPM 1a

Variations of the Earth’s surface temperature for the past 140 years


SPM 1b

Variations of the Earth’s surface temperature for the past 1,000 years


Concentration of Carbon Dioxide and Methane Have Risen Greatly Since Pre-Industrial Times

Carbon dioxide: 33% rise Methane: 100% rise

The MetOffice. Hadley Center for Climate Prediction and Research.

BW 5


The last 160,000 years (from ice cores) and the next 100 years

Time (thousands of years)

160 120 80 40 Now

–10

0

10

100

200

300

400

500

600

700

CO2 in 2100(with business as usual)

Double pre-industrial CO2

Lowest possible CO2

stabilisation level by 2100

CO2 now

Temperature

difference

from now °C

CO

2 c

on

ce

ntr

ati

on

(p

pm

v)


The Greenhouse Effect

Solar radiation

Long-wave radiation


The Enhanced Greenhouse EffectSolar (S) and longwave (L) radiation in Wm2 at the top of the atmosphere

S L

236 236

T = 18°C

S L

236 232

CO2 x 2

S L

236 236

CO2 x 2

S L

236 236

CO2 x 2+ Feedbacks

H2O (+60%) Ice/Albedo (+60%)Cloud?Ocean?

TS = 15°C TS = 15°C TS ~ 1.2K TS ~ 2.5K


Variations of the Earth’s surface temperature; 1000 to 2100


The Carbon Cycle


Human Perturbation of the Carbon Cycle


Partitioning of CO2 uptake using O2 measurements


Changing Land Use

Changing land use could influence atmospheric CO2 concentration.

Hypothetically, if all of the carbon released by historical land-use changes could be restored to the terrestrial biosphere over the course of the century (e.g., by reforestation), CO2 concentration would be

reduced by 40 to 70 ppm.


Radiative Forcing


SPM 3


Estimated solar irradiance variations 1750-2000


Main climate changes

Sea level rise

Higher temperatures - especially on land

Hydrological cycle more intense

Changes at regional level


Sea-level transgression scenarios for Bangladesh

Adapted from Milliman et al. (1989).


Percent of the continental USA with a much above normal proportion of total annual precipitation from

1-day extreme events (more than 2 inches or 50.8mm)

Karl et al. 1996

BW 7


Patterns of Climate Response


The 1997/98 El Niño Strongest on Record*

*As shown by changes in sea-surface temperature (relative to the 1961-1990 average) for the eastern tropical Pacific off Peru

El Niño years

La Niña years

BW 14


Global ocean circulation

A simplified view of the global thermohaline conveyor belt, showing cooling and downwelling in the North Atlantic, warming and freshening in the southern hemisphere, and return flow as a warm surface current.

Cooling

Warm and less saline Antarctic circumpolar current

Warmsurfacecurrent

Intermediatewaters


Stabilisation of Climate


UNITED NATIONS FRAMEWORK CONVENTION ON CLIMATE CHANGERio de Janeiro : June 1992

ARTICLE 2: OBJECTIVE

The ultimate objective of this Convention .... is to achieve, .… stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system.

Such a level should be achieved within a time-frame sufficient :

to allow ecosystems to adapt naturally to climate change. to ensure that food production is not threatened, and to enable economic development to proceed in a sustainable manner.


CO2 emissions for SRES and stabilisation scenarios

jth 17-07-2001 1 cop6bis/sbsta briefing on wgi contribution bonn: tuesday 17 july 2001 the...

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