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Potential Impacts of Global Warming

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Lecture 16 Potential Impacts of Global Warming * * Northward Shift: Example 2 Sugar Maple Prediction: It will disappear from the U. S. * Northward Expansion - 1 ... – PowerPoint PPT presentation

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Title: Potential Impacts of Global Warming


1
Lecture 16
  • Potential Impacts of Global Warming

2
IPCC Reports
  • Three working groups ? 3 reports
  • WG1 Science
  • (What weve been talking about)
  • WG2 Impacts and Adaptation
  • Impacts Changes in society, ecosystems, etc.
  • Adaptation Learning to live with climate change
  • WG3 Mitigation
  • Reducing the rate of climate change

3
Arctic Impacts
  • Large reduction in summer sea ice
  • Arctic could be ice-free in summer by end of
    century

4
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5
Permafrost
  • Permafrost soil that remains frozen throughout
    the year
  • Warming ? softening of permafrost

6
Permafrost landslide in Yukon
7
Alaska
Softening of ground makes it more vulnerable to
erosion by waves
8
China-Tibet Railway
Some scientists question whether the 4-billion
rail line will survive as is or require major
reconstruction.
9
Glaciers and Ice Sheets
  • Mountain glaciers will continue to shrink
  • Greenland ice sheet will very probably lose mass
  • Antarctica (?)
  • West Antarctic Ice Sheet www.realclimate.org

BBC Video
10
Sea Level
  • Melting glacial ice and thermal expansion will
    cause sea level to rise
  • Estimated rise
  • Low-emission scenario 18 38 cm
  • High-emission scenario 26 59 cm
  • Estimates are probably too low
  • Contribution from ice sheets was not taken into
    account!

11
Impact of Rising Sea Level
  • Greatest in countries with heavily populated
    coastal regions, e.g. Bangladesh and in
    small-island nations

12
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13
  • 6 million people live within one meter of sea
    level!
  • Problem aggravated by sinking of land

14
Small Island Nations
15
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16
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17
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18
Highest Point 5 m above sea level
Population 11, 000
19
Fresh Water Supplies
  • Warming ? shrinking glaciers, reduced snowfall in
    mountains
  • Problem 1/6 of world population depends on
    glacial snow melt for drinking water

20
Precipitation
  • Models project increases in precipitation in some
    regions, decreases in others
  • Regions of decrease include
  • Southwestern U. S., Mexico, Central America,
    Caribbean
  • Mediterranean
  • Regions of increase include
  • Canada, most of Asia

21
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22
Soil Moisture, Runoff
  • ?precip. ? ?soil moisture and runoff
  • But, can have ?soil moisture even with ?precip.

23
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24
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25
Effect on California
  • Warming ? less snowfall in mountains
  • ? less summer runoff
  • ? less water in summer for
  • irrigation
  • hydroelectric power
  • drinking water
  • Loss of salmon habitat

26
More about precipitation
  • Models project increased variability
  • ? increased flooding and increased droughts!
  • Another problem increased demand for water.

27
Agriculture
  • Reductions in soil moisture ? reduced crop yields
  • However, areas with increased soil moisture
    could benefit
  • (If warming isnt too large.)

28
Other Potential Agricultural Benefits of Warming
  • Increased growing season in higher latitudes
  • Could benefit Canada, Russia
  • Beneficial effects of increased CO2 could offset
    damaging effects of reduced soil moisture
  • Called CO2 fertilization
  • Only works if warming is relatively small

29
Ecosystems
  • In past, ecosystems have been able to adapt, but
  • resilience of many ecosystems is likely to be
    exceeded by 2100
  • Effects of climate change aggravated by
  • increased human demands
  • fragmentation of habitats

30
Ecosystems, continued
  • Up to 30 of species at increasingly high risk
    of extinction if average global temp increase
    above 2 -3?C
  • Oceans becoming more acidic
  • Will hurt organisms that make shells

31
Carbon Cycle
  • Now, biosphere is a net sink of carbon
  • i.e., carbon uptake gt carbon released
  • By mid-century, biosphere likely to become a net
    source of carbon
  • i.e., carbon release gt carbon uptake
  • (mainly due to increased rate of decay)
  • Ocean carbon uptake will diminish
  • Result Faster rise of CO2

32
Impacts on U. S. Forests
  • Each tree species requires a specific environment
    for optimum growth
  • Climate change will cause a shift in tree
    habitats
  • Projections of habitat changes
  • http//www.fs.fed.us/ne/delaware/atlas/web_atlas.h
    tml

33
Northward Habitat Shift Example 1
White Ash
Yellow lost habitat
Note northward shift
34
Northward Shift Example 2
Sugar Maple
Prediction It will disappear from the U. S.
35
Northward Expansion - 1
Laurel Oak
Green Current habitat Blue Additional habitat
Range increases
36
Northward Expansion - 2
Southern Red Oak
Range increases
37
No Change Example
Red Maple
38
Complex Pattern Example
Black Oak
Yellow Lost Habitat Blue Expanded habitat
39
Forest Fires
  • In western U. S., warming ? more forest fires

40
Tropical Cyclones basic info
  • Called hurricanes in Atlantic, eastern Pacific
  • Called typhoons in western Pacific (north of
    equator)
  • Energy source heat stored in oceans
  • Theory warmer oceans ? stronger storms
  • (There is evidence this already happening)

41
Human Health
  • More deaths from heatwaves
  • Like 1995 Chicago heat wave
  • Increases in some tropical diseases
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