Title: Turning Up the Heat on the Future: Global Warming and Its Consequences
1Turning Up the Heat on the Future Global Warming
and Its Consequences
- Dr. John Heinrichs
- Department of Geosciences
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3Presentation outline
- Basics about global warming and the greenhouse
effect - The most recent findings about changes in the
polar regions - Have we passed the tipping point?
- What to do for the future?
4What is the greenhouse effect?
- Certain gases are transparent to visible light
but absorb infrared - Called greenhouse gases
- Include water vapor (H2O), carbon dioxide (CO2),
methane (CH4) - Greenhouse gases allow sunlight to pass through
and warm the surface - When the Earth emits infrared, it is absorbed and
reemitted (trapped) by the greenhouse gases - Without the greenhouse effect, Earths surface
would be 30 colder than it is - Venus has a much thicker CO2 atmosphere, and a
much stronger greenhouse effect (surface
temperature 490 C)
5Schematic diagram of the greenhouse effect
6Greenhouse gases over the past millenium
- Exponential increase over the past 1000 years in
CO2, CH4, and N2O is clear - CO2 concentrations have increased by about 35
since pre-industrial times - Methane concentrations have more than doubled
Source 2001 IPCC report
7The global instrumental temperature record
- Quality instrument measurements begin about 1850
- Global record shows approximately 1 C increase
over past 150 years - Note Dust Bowl peak around 1940
- Warming is greater in Northern Hemisphere than
Southern
8Seasonal temperature trends
- Temperature increase has been greater in winter
than any other season key smoking gun
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10- Key findings
- Cold nights and days are decreasing, warm nights
and days increasing - Decreases in cold nights, increases in warm
nights are much greater than corresponding
changes during daytime - Consistent with warming caused by enhanced
greenhouse effect
11The long-term temperature record
- The past 100 years have been the warmest in the
past 1000
Source IPCC, 2001
12Sea ice trends
13Temperature change by 2100 with CO2 stabilization
at 450 ppm
Source IPCC, 2001
14Temperature change by 2100 with continued CO2
increases
Source IPCC, 2001
15Global mean surface temperature under different
scenarios
Source IPCC, 2001
16Predicted precipitation changes
- Overall increase in precipitation
- Some areas (Arctic, Sahara, Antarctic) become
wetter - Other areas become drier
Annual mean precipitation change 2071 to 2100
Relative to 1990 Source IPCC, 2001
17Sea ice will continue to decline dramatically
18Sea level rise
- Global sea level will rise between 0.3 and 0.9
meters, depending on scenario - Causes melting polar ice, thermal expansion of
water
Source IPCC, 2001
19Some recent results (mostly from the polar
regions)
20Why are the polar regions so important?
- Ice and snow are white losses in cover result
in darkening of the Earth and an acceleration
(positive feedback) of warming - Predicted by models to show earliest impacts of
warming - Continental ice sheets contain large quantities
of water, sufficient to raise sea level
substantially - Ice sheets have large thermal inertia take a
long time to melt and a long time for melting to
stop
http//www.msc.ec.gc.ca/crysys/education/snow/snow
_cover_loop.gif
21The Greenland Ice Sheet
Thickness 3300 m max Sea level equivalent 7 m
http//www.climatechange.umaine.edu/Research/proje
cts/Greenland/home.htm
Source Box et al., 2005
22The Antarctic ice sheet
Thickness 4700 m max, 2200 m average Sea level
equivalent 70 m
http//science.nasa.gov/headlines/y2002/images/ice
/icecontinent.gif
http//students.washington.edu/srh13/SPole/Geograp
hy.html
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25- Key findings
- Greenland mass balance is negative and decreasing
- Results consistent with other recent studies
26- Key findings
- Greenland mass balance has become more negative
in most recent period
27- Key finding
- Greenland ice sheet is thickening in center,
losing mass along W coast
28Box, J.E., D.H. Bromwich, B.A. Veenhuis, Le-S.
Bai, J.C. Stroeve, J.C. Rogers, K. Steffen, T.
Haran, S.-H.. Wang, Greenland ice sheet surface
mass balance variability (1988-2004) from
calibrated Polar MM5 output, J.Clim., 2005.
- Key findings
- Net mass loss for entire ice sheet of 78 km3/yr
- Thickening in center, thinning along coasts (both
trends increasing) - Contribution to sea level 2.2 mm from 1991 to
2000
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30- Key findings
- Greenland showing slight mass increase
- Thickening in center
- Thinning along coasts
- Antarctica showing mass loss
- East Antarctic ice sheet thickening
- West Antarctic ice sheet thinning
- All results consistent with greenhouse effect
predictions - Overall contribution to sea level of all ice
sheets 0.05 0.03 mm/yr
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32From Stroeve et al., 2005
33Are we at a tipping point?
- Evidence suggests sea ice may be past the tipping
point
34Current polar climate processes
Polar climate processes after loss of permanent
ice
- Key findings
- Arctic sea ice cover is decreasing, eventually
permanent sea ice will be gone or greatly reduced
in next century - Once permanent pack ice is gone, no feedback
process will exist to reverse trend
35Are we at a tipping point?
- Ice sheet evidence generally suggests we are past
the tipping point - Most studies show Greenland with a negative mass
balance, all show increasing thinning along ice
sheet margins - All recent studies show Antarctica with negative
mass balance
36What to do about the future?
37Possible futures CO2 concentrations
Source IPCC, 2001
38Projected levels of atmospheric CO2 during the
next 100 years would be higher than at anytime in
the last 440,000 yrs
Source IPCC, 2001
CO2 Concentration (ppmv)
39Possible futures - temperature
Source IPCC, 2001
40Long-term predictions
- Some effects continue long after CO2 emissions
reduced - Note ice melt may continue for several thousand
years (ice-albedo feedback)
41Major greenhouse gas emitters
- Most greenhouse emissions come from developed
countries - US and Australia are leaders
- The US, with 6 of the worlds population,
contributes 25 of the total emissions
42Sources of emissions
- Industry (primarily electric power generation and
cement production) is the leader - Transportation is second
43Where will future emissions come from?
- The US and Western Europe are the current leaders
- Developing countries (particularly India, China,
and Eastern Europe) will contribute a much larger
share in the future
44Stabilization of atmospheric concentrations of
CO2 will require emissions reductions globally
Source IPCC, 2001
45Who will have to reduce?
- Industrialized countries are greatest users of
energy and carbon emitters - must reduce first - Developing countries increasing energy
consumption faster must reduce as well
46How to reduce emissions
- Few technological solutions, if any
- No way to remove carbon fast enough (planting
crops, trees too slow, requires lots of water) - Nuclear power can help, but long lead time to
build plants - Scrubbers can be built to remove CO2, but are
very expensive - Only realistic guaranteed solution is dramatic,
rapid lifestyle change - Lower, more efficient electric power usage
- Reduced use of fossil fuels for transportation
(goodbye to SUVs and large personal cars) - Higher-density housing
- Lifestyle changes are very unpopular, but if not
done reductions will be involuntary eventually