Global Climate Change
Dr. David Karowe
Department of Biological Sciences
Western Michigan University
Earth’s climate has always been changing
Over the past 800,000 years:
~ 100,000 year climate cycles, due to cyclic changes in
amount of incoming solar radiation
1
Since 1900, Earth has warmed by ~ 0.8o C
Temperature Change (oC)
10 warmest years in history: 2002-2010, 1998*
- warmest year: 2010
- rate of waming is 10-100 times faster
than in at least the last 800,000 years
Temperature difference relative to 1950-1980
http://data.giss.nasa.gov/gistemp/animations/
2
Can climate change be due to “natural variation”?
Solar Irradiance
For the last 30 years, solar irradiance has been
decreasing
Since 1900, natural factors would have caused
a slight cooling of Earth
3
Bottom line: At least 95% of global warming
is due to human activities
Fossil fuel use (~75%)
Deforestation (~20%)
What’s the Greenhouse Effect?
GHGs let visible
wavelengths
pass, but absorb
and re-radiate
heat
Solar energy
passes through
Some
outgoing
heat is
trapped
Some greenhouse
effect is necessary
for life on Earth
4
85% of U.S. energy comes from fossil fuels
Size proportional to population
5
Size proportional to national CO2 emissions
Midwest would be 4th highest emitting country
U.S. emits the most carbon per person
6
Average US citizen generates 20 tons of CO2 per year
1 gallon of gas
19 lbs CO2
On average, each molecule of CO2
stays in the atmosphere for > 100 years
In just the last 150 years, atmospheric CO2
increased from 280 to >390 parts per million (ppm)
7
Temperature Change (oC)
CO2 increase is the main cause of global warming
What has happened over the last 50 years?
1. Arctic summer sea ice has decreased by ~40%
- likely will disappear by 2100
- very strong positive feedback (albedo effect)
8
2. Glaciers have been melting worldwide
e.g. Peruvian glacier Qori Kalis
1978
2000
3. Greenland is melting and Antarctica is shattering
9
4. Permafrost has been melting
- CO2 and methane from decomposition enter
atmosphere
5. Severe rainstorms have become more common
- 50% increase in southwest Michigan since 1948
10
6. Flooding has increased worldwide
7. Droughts have also increased worldwide
11
What’s been happening in Michigan?
Michigan has warmed by ~0.8 oC since 1950
12
Freeze time of Grand Traverse Bay has decreased by
over a month since 1900
2011 was Michigan’s 3rd wettest spring on record
- much of MI
received
50-100%
more rain
than normal
13
But by late July, 51% of MI was “abnormally dry”
As a result, Michigan experienced flooding this spring
14
And there was extensive flooding along Mississippi
Tunica, Mississippi
Much of the U.S. had an unusually warm summer
15
In late September, 43% of U.S. was in drought
Sept 2011
South central states experienced “Exceptional Drought”
Right now, 57% of U.S. is in drought
January 17, 2012
South central states experienced “Exceptional Drought”
16
Have there been any biological responses yet?
Some species have shifted their geographic ranges toward
higher latitudes
(blue=recorded, yellow=well-recorded, red=heavily recorded)
Other species have shifted their geographic ranges toward
higher altitudes
e.g. the hardwood-conifer transition zone on Vermont
mountains moved upslope ~100 meters from 1962-2005
17
More species have shown phenological shifts
e.g. timing of spring migration, flowering
Many plant species now leaf out and flower
significantly earlier
- e.g. of 385 British species, 16% now flower significantly
earlier than in 1954-1990
- only 3% flowered significantly later
Earlier
Later
18
Plant species that have been tracking climate change
have fared better than species that have not
- in Thoreau Woods over the last 150 years, major
declines for species without phenological advancement
Ericaceae
Rosaceae
Cornaceae
And bird species that have been tracking climate
change have fared better than species that have not
Increasing
- e.g. 100 European species since 1990
Decreasing
Stock Dove
Earlier
Later
Black-throated Loon
19
Climate change is already affecting human health
World Health Organization estimates that climate
change already kills 150,000 people annually
- death rates are greatest in Africa
What’s been happening so far?
1. Earth’s climate is already changing rapidly
a. more rapid warming than in at least 800,000 years
b. more severe rainfall events
c. more and stronger droughts
2. Many (but not all) of Earth’s non-human species are
already responding
a. some are showing geographic shifts
b. some are showing phenological shifts
c. many species that are not tracking climate change
are already declining
3. Human health is already being adversely affected
20
What does the future hold?
Climate change is very likely to accelerate
Earth is expected to warm by at least 2-4o C by 2100
“Business
as usual”
4o
2o
Alternate
energy
sources
21
Will a 4o temperature rise matter?
When Earth was 5o cooler:
Severe rainstorms will continue to increase
22
In the future, most summers are likely to be hotter
than any experienced thus far
Much of the U.S., including Michigan, is likely
experience more, stronger droughts
23
Many areas are predicted to experience “novel
climates” by 2100
Low
Moderate
High
Probability of novel climate
Temperature rise is likely to persist for >1,000 years
after we stop emitting greenhouse gasses
24
How are plants and animals likely to be affected by
future climate change?
Overall, tree species richness is predicted to decline
substantially throughout the U.S. by 2100
Current
2100
25
In Michigan, sugar maple is predicted to decline
by >60% by 2100 under “Business as Usual”
Future Low
Current
Future High
African mammals are likely to be adversely affected
Of 227 species, 20% are predicted to be extinct by 2080
even with full dispersal
- 40% extinction with no dispersal
26
Most Western Hemisphere amphibian species are
predicted to be adversely affected by climate change
of 413 species:
⅔ lose >50% of range
⅜ lose >90% of range
area of
greatest
vulnerability
Birds in high northern latitudes are particularly
vulnerable to habitat loss due to climate change
White-winged
Crossbill
Eurasian
Dotterel
27 northern species lose,
on average, 74-84% of
suitable habitat by 2080
27
Possible loss of all coral reefs with 3o rise
and >650 ppm CO2
Globally, if we allow Earth to warm by 3o C,
20-50% of species may be committed to extinction
28
This is probably the worst time in Earth’s history for
species to track climate change via dispersal
- because humans have fragmented landscapes
Humans have impacted ~75% of Earth’s land surface
(red = impacted)
29
In Michigan, many barriers to dispersal exist
(images courtesy of August Froehlich)
How can climate change affect human health?
1. Increased heat stress and/or decreased cold stress
2. Change in frequency and/or severity of disease
3. Change in air quality
4. Change in rates of malnutrition
5. Change in frequency and/or severity of conflict
30
By 2100 in Europe, every other summer could be like
2003, when a heat wave killed up to 80,000 people
2003
1900
2100
Year
Michigan will experience many more days over 90o F
31
In the future, most summers are likely to be hotter
than any experienced thus far
Climate change is likely to cause an increase in
several vector-borne diseases
e.g. malaria
1,000,000 deaths annually
Anopheles
32
Most studies predict increase in malaria, but change
depends on climate scenario
+2o C
+10% summer rain
- 10% winter rain
+4o C
+20% summer rain
- 20% winter rain
Climate-induced increases in tropospheric ozone is
predicted to cause ~2 million deaths by 2050
Annual deaths due to O3 above pre-industrial level
- health costs estimated at $580 billion per year
33
By 2030, most of the important crops in South Asia
(SAS region) are predicted to have reduced yields
SAS = India, Pakistan (30% of world’s malnourished
people)
red = most important
orange = important
yellow = less important
Most of the important crops in China (CHI region) are
predicted to have increased yields by 2030
CHI = China (18% of world’s malnourished people)
red = most important
orange = important
yellow = less important
34
The important crops in East Africa (EAF region) are
predicted to have increased or decreased yields by 2030
EAF = 9% of world’s malnourished people
red = most important
orange = important
yellow = less important
What are the biggest climate change effects on
human health?
35
Climate change is predicted to increase civil wars in
six African regions by 5-10% by 2030
- overall increase
in sub-Saharan
Africa of about
about 50%
In 2006 Center for Naval Analyses (CNA) convened a
Military Advisory Board of 11 retired three-star and
four-star admirals and generals to assess the national
security implications of climate change
Major Findings:
1. Projected climate change poses a serious threat to
America's national security.
2. Climate change acts as a threat multiplier for instability
in some of the most volatile regions of the world.
3. Projected climate change will add to tensions even in
stable regions of the world.
4. Climate change, national security and energy
dependence are a related set of global challenges.
36
Recommendations:
1. The national security consequences of climate change
should be fully integrated into national security and
national defense strategies.
2. The U.S. should commit to a stronger national and
international role to help stabilize climate changes at
levels that will avoid significant disruption to global
security and stability.
3. The U.S. should commit to global partnerships that
help less developed nations build the capacity and
resiliency to better manage climate impacts.
Developed countries are causing the problem, but
developing countries experience most health costs
Countries proportional to
CO2 emissions (1950-2000)
Countries proportional to
climate-sensitive health effects
37
Emissions reductions need to be rapid and large
- 80% reduction by 2050 to avoid worst scenarios6
Urgent need for alternate energy sources
solar
wind
Wind power could supply 16 times current U.S.
electricity demand using only onshore turbines
- Ohio can supply 5.4 times its current use
38
Concentrating Solar Power (CSP) is very promising
Central tower
Parabolic trough
A small portion of the Sahara desert could supply all
of Europe’s electricity (and the world’s)
39
Worst case scenario:
< 0.01%
0.3%
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