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December 2002
Section 5aSection 5a
Global Impacts of Global Impacts of Climate Change (1)Climate Change (1)
Ecological systems are sensitive to climate change
• Biological systems have already been affected by changes in climate at the regional scale
• The structure and functioning of ecological systems will be altered and the biological diversity will decrease, especially in niche systems, e.g., alpine and arctic forests, especially tropical and boreal forests are vulnerable due to
changes in disturbance regimes (pests and fires), likely to change species composition
coral reefs are threatened by increases in temperature, more than increases in sea level
the current terrestrial uptake of carbon will likely diminish over time and forest systems may even become a source of carbon
There will be large shifts in the eventual distribution of global ecozones
1xCO2 2xCO2
…causing a major redistribution of global forest types
Vulnerable species will be increasingly threatened by changing habitat and food supply
There are also many reasons for concern about the impacts on humans
• A place to live– sea level rise– floods
• Food to eat– crop losses in tropical regions– droughts
• Health– extreme weather– disease/air quality
• Economic well-being
Changing ice sheets
Receding glaciers
Rising ocean temperatures
Sea levels will rise
…although the rate of rise will vary from region to region
1991 2001 2011 2021 2031 2041 2051 2061 2071 2081 2091
Year
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7metres
Eastern Pacific
Equatorial Atlantic
NW Atlantic
Arctic Ocean
Many people will be affected
Coastal areas highly vulnerable to a 44 cm Sea-level Rise by the 2080s
Assuming 1990s Level of Flood Protection
Some small island states may simply disappear
Examples of vulnerable islands:•Marshall Islands•Tuvalu•Kiri•bati•Maldives
Deltaic countries like Bangladesh would be particularly vulnerable
Today
1 M sea level rise
•20.7% land loss•14.8 million people affected
Other examples of costs of sea level rise:
• Impacts – for 0.5 m rise
• 32% of urban Egypt property flooded, loss of US$ 35 B• $20 to 150 billion property loss in the USA
– for 1 m rise• 17 million people directly affected by flooding in Vietnam• US$410 property loss in Germany
• Protection Costs– for 1 m rise,
• ~US$30 B for Germany• For 1 m rise, ~$200 B for Japan
Inland flood disasters may become more frequent as rains become more intense
El Nino - Southern Oscillation behaviour may change significantly
1860-1980 distribution 1980-2100 distribution
Nino-3 Monthly SST Anomaly (deg. C) Nino-3 SST Monthly Anomaly (deg. C)
…possibly causing both intense El Ninos and La Ninas to become more frequent
0
10
20
30
40
50
601860-19801980-2100
Neutral
La Nina El Nino
Ch
ange
in P
erce
nt
of T
otal
Eve
nts
Nino-3 Monthly SST Anomaly (deg. C)
<-1.5C -1.5 to -1.0
-1.0to -0.5
-0.5to 0.5
0.5 to 1.0
1.0 to 1.5
>1.5
40-49 50-59 60-69 70-79 >80
Wind Speed (m/s)
0
5
10
15
20
25
30Number of Cases per year (NW Pacific)
Control
High CO2
The number of intense hurricanes may increase in some areas