Climate Change: an Introduction

ecbi Workshops 2007

Claire N ParkerEnvironmental Policy Consultant

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for sustained capacity building in support of international climate change negotiations

pour un renforcement durable des capacités en appui aux négociations internationales sur les changements climatiques

The greenhouse effect in the atmosphere

Natural and man-made carbon cycles

OCEANLAND

ATMOSPHERE

9060

5.41.7

1.91.9

Annual transfers,natural and human-made (GtC)

3.3

Source: IPCC

CO2 is major contributor to global warmingCurrent emissions, effect over next 100 years

Methane24%

Carbondioxide

63%Nitrous

oxide 10%

Others3%

Sources of Greenhouse Gases

• CO2 from fossil fuel use (mainly power generation, transport) and land use change (e.g. deforestation)

• CH4 (methane) and NO2 (nitrous oxide) primarily from agriculture

Stages in predicting climate change

CONCENTRATIONSCO2, methane, etc.

HEATING EFFECT‘Climate Forcing’.

IMPACTSFlooding, food supply, etc.

Scenarios frompopulation, energy,economics models

Carbon cycle andchemistry models

Gas properties

Coupled climatemodels

Impacts models

CLIMATE CHANGETemp, rain, sea level, etc.

EMISSIONS

feed

back

s

The climate system

Strong global warming observed since 1975

IPCC’s AR4 2007

Warming is unequivocal… now clearly evident in many aspects of the climate system

Signs of climate change

• Earth surface has warmed by 0.74C over last century

• Sea levels rose 20cm last century

• Glaciers, snow cover and sea ice all declining

• More heat-waves, droughts and extreme rainfalls

• More intense cyclones

Carbon dioxide in the atmosphere: rapid rise due to human activities

CO2 from fossil-fuel burning: rapid rise since 1950

Source: CDIAC, ORNL

Other Greenhouse gases

Similar patterns are observed for

methane (CH4) and nitrous oxide (NO2)

AR4: high confidence in radiative forcing data

Anthropogenic is > 10 times that of solar since 1750

AR4: models are getting better

• Models are used to simulate the warming of the last 150 years

• Their results correlate with anthropogenic + natural warming

• Natural causes can’t explain what has happened.

AR4: observed vs. modelled global climate change

What do models predict?

• AR4: There is now higher confidence in projected patterns of warming, and other regional-scale features, including changes in wind patterns, precipitation and some aspects of extreme events and changes in ice cover

This century global temperature likely to be between 1.8 and 4 C above today’s

• A further warming of about 0.6C likely from past emissions alone

• Scale of warming depends on emissions:

Low scenario 1.1 – 2.9 C

High scenario 2.4 – 6.4 C

Geographical patterns of warming

Warming expected to be greatest over land and at high northern latitudes

•Sea levels will rise by 18 to 59 cm by 2100. Additional 10-20 cm or more may come from Greenland and Antarctic ice sheets•Snow cover, glaciers and sea ice will continue to decline•Rainfall and wind patterns will change•Extreme events (rainfall and droughts) more frequent•Tropical cyclones more intense •Meridional Overturning Circulation in N Atlantic likely to slow down by 25%

Other changes in climate will continue

The Atlantic Ocean’s Circulation System

Changes will continue for centuries,

even if GHG concentrations were to be stabilised by 2100

Emissions to 2000, and IPCC projections to 2100

Towards dangerous levels

Past and projected CO2 emissions from fossil fuel burning

IEA World Energy Outlook 2004

References & Acknowledgements • Climate Change and The Greenhouse Effect, A

briefing from the Hadley Centre, Dec 2005- enquiries@metoffice.gov.uk

• IPCC, Climate Change 2001 Synthesis Report of the Third Assessment Report

• IPCC, AR4, 2007

• DEFRA, UK (Department for Environment, Food and Rural Affairs)

Thank You

Claire N Parker

claire.n.parker@btopenworld.com

+44 1763 209 066

+44 7769 66 47 01