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