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Unformatted text preview: Process of Science Idea for Today: Consider the difference
between evidence for
“correlation” and “causation”. How to predict what climate
change will do to Earth
• Make computer models, check them by
comparing to past history & current
• Extrapolate trends observed on Earth.
• Study other worlds, Mars and Venus,
under even more extreme conditions.
• Wait and see what happens to the Earth. Planets as Homes for Life A tale of three planets Why do we think Mars once
had flowing water? Surface of Mars appears to have ancient river beds 1 Eroded
crater Closeup of eroded crater Condition of craters indicates surface history Low-lying regions may once have had oceans Predicted mission time: 3 months
Actual mission age: 48 months as of Jan 19, and still
going… 100,000 pictures so far
Blue regions indicate water ice near surface Spirit: 7 km
Opportunity 11 km: deep within Victoria Crater 2 Where are Spirit and
Check at the JPL website. What determines a planet’s
“blueberry” rocks and other features: there was
definitely surface water on Mars a long time ago. The energy emitted by a planet in infrared light equals the
amount of sunlight energy it absorbs Conservation of energy Mercury
(878 F) 288 K
( 15 C)
( 59 F)
(-58 F) Daily variations in temperature
depend on a planetʼ s rotation
rate Temp vs. length The intensity of sunlight on a planet depends
on its distance from the Sun Temp vs. orbital r 3 How does a planet’s
reflectivity alter the surface
temperature? Reﬂectivity Pred. Temp Venus 72% -43 C 470 C Earth 36% -17 C 15 C Moon 7% 0C Mars 25% -55 C A planetʼs reﬂectivity (albedo) determines how much
sunlight it absorbs Actual Temp. 125 C (day)
-175 C (night) How does the greenhouse
effect alter surface
temperature? -50 C Molecules let visible light through but can absorb infrared
Fig 7.14 Earthʼs atmosphere absorbs
light at most wavelengths. 4 Pred. Temp Greenhouse effect: Actual Temp. Warming (H2O, CO2, CH4) Venus -43 C 470 C 513 C Earth -17 C 15 C 32 C Moon 0C Mars Certain molecules let sunlight through but trap escaping
infrared photons -55 C 125 C (day)
-175 C (night)
-50 C -- 5C Mars has seasons: CO2 can freeze in polar caps
Mars has weather in a thin atmosphere of CO2 Mars once had a much thicker CO2 atmosphere
Dramatic climate change occurred about 3 billion years
ago The CO2
Why Mars lost
is still under
investigation 5 Was Mars too small?
Thick CO2 clouds of Venus lock heat in Marsʼ interior cooled off, lost its magnetic ﬁeld, atmosphere
lost to stripping by early solar wind? Where is Earthʼs
& Ocean CO2 dissolves in ocean and gets locked into rocks How has Earth’s climate
changed during its history? A runaway greenhouse effect would occur if Earth moved to
Venusʼ orbit 6 Earthʼs ice ages
end as oceans
freeze over and
CO2 into the
atmosphere Greenland, then and now How is human activity
affecting Earth’s climate? CO2 content of Earthʼs atmosphere is steadily increasing.
The rate of increase is higher now than in the last 400,000 years We are conducting a planet-sized climate experiment. The choice to act or not is ours. And the consequences
will be experienced by us & our children. Increased CO2 is causing global warming: causation
established by testing the model “Fossil record” of CO2 from ice cores 7 CO2 at 450 ppm
• Melt Greenland, West Antarctic ice sheets
• Catastrophic rise in sea levels
• 35 years away at current rate of 2 ppm/year
• Need to reduce CO2 emissions by 50% to avert
disaster (Princeton’s Socolow & Pacala: “12 of
15 wedges” ; 1 wedge = 1 billion metric tons of
CO2 per year) What saves a billion tons/year?
“1 wedges”: Nat. Geo. 10/2007
Efficiency and Conservation
Improve fuel economy: 2 billion cars expected
by 2057, get 60 mpg
Reduce miles/car/year from 10,000 to 5,000
Increase efficiency of household power use by
25% What’s being done now?
• Not much - Europe and Japan have
begun to reduce emissions
• US contributes 25% of total emissions,
will increase carbon output by 20% by
• China building 1 coal-fired plant/week What can be done?
Carbon Capture and Storage
Capture CO2 and store underground at 800 large coalfired plants or 1600 natural gas plants
Low Carbon fuels
Replace 1400 large coal-fired plants with natural gas
Displace coal by increasing nuclear power generation to
3 times current capacity Improve coal-fired power plant efficiency to 60%
from 40% What can be done?
Renewables and Biostorage
Increase wind-generated power to 25x current capacity.
Increase solar power to 700x current capacity Sources of CO2 that you control
Combustion puts 6 million tons of C02 in the
atmosphere every year. Increase wind power to 50x current capacity to make hydrogen for
Increase ethanol biofuel production to 50x current (1/6 of ALL
cropland required.) Corn is not the way, though!!!
Stop all deforestation.
Stop normal plowing (speeds decomposition.) 8 Examples of human success in
• Lead controls in emissions & gasoline & paint
reduced lead levels in blood, improved IQ scores
• CFC regulation led to (slowly) smaller ozone hole.
• Insurance industries have a stake in changing
behavior: reducing emissions, smarter land use,
changing perception of risk
• Note that Carbon cost is not included in fuel cost
now: actual fuel costs would motivate change.
Change is possible! (But we need to start now,
make it economically necessary.) What can you do?
• Drive (and fly) less.
Walk, bike, take public transportation.
Eat less meat (especially red meat)
Thermostat management: cooler in winter,
warmer in summer
Turn stuff off, unplug when not in use.
Invest in alternative energy, renewables,
Buy a hybrid car.
Let your government know how you feel.
Vote: registration deadline is Oct 6 Investor Alert (Fortune Mag.)
“Climate change is no longer a fringe
issue…these trends present enormous risks
Cost of natural disasters 2005: $225 billion, in
2004: $118 billion
Reinsurance giant Swiss Re: “Global warming
has accelerated from a problem which might
affect our grandchildren, to one that could
significantly disturb the social and economic
conditions of our lifetime.”
www.ceres.org Be able to answer
• What is the evidence for (surface) water on
• What factors affect the temperature on a planet
• Explain the greenhouse effect of atmospheres,
including runaway greenhouse.
• What is the evidence for global warming and
human’s influence on greenhouse gases in the
• Why are conditions on Mars and Venus so
different from those on Earth? 9 ...
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This note was uploaded on 11/13/2011 for the course ISP 205 taught by Professor Donahue during the Fall '08 term at Michigan State University.
- Fall '08