Transcript AR4: observed vs. modelled global climate change What do models

european capacity building initiative
initiative européenne de renforcement des capacités
ecbi
Climate Change: an Introduction
ecbi Workshops 2007
Claire N Parker
Environmental Policy Consultant
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
Annual transfers, natural and human-made (GtC)
1.7
1.9
ATMOSPHERE
3.3
5.4
1.9
90
60
OCEAN
LAND
Source: IPCC
CO2 is major contributor to global warming
Current emissions, effect over next 100 years
Methane
24%
Nitrous
oxide 10%
Others
3%
Carbon
dioxide
63%
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
Scenarios from
population, energy,
economics models
EMISSIONS
CONCENTRATIONS
Carbon cycle and
chemistry models
HEATING EFFECT
‘Climate Forcing’.
CLIMATE CHANGE
feedbacks
CO2, methane, etc.
Gas properties
Temp, rain, sea level, etc.
Coupled climate
models
IMPACTS
Impacts models
Flooding, food supply, etc.
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 0.74C
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
Anthropogeni
c 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 0.6C
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
Other changes in climate will
continue
•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%
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 [email protected]
• IPCC, Climate Change 2001 Synthesis
Report of the Third Assessment Report
• IPCC, AR4, 2007
Thank You
Claire N Parker
[email protected]
+44 1763 209 066
+44 7769 66 47 01