Transcript Lecture

Greenhouse gases, Climatic
modeling, what can be done?
Not Just CO2, Many Others!!
CH4 (methane)
N2O (Nitrous oxide – AKA Dinitrogen
H2O (Water vapor)
CCl3F (Freon 11)
CCl2F2 (Freon 12)
Greenhouse factors for these
common gases
Greenhouse factor Tropospheric Abundance (%)
3.6 X 10-2
1.7 X 10-3
3 X 10-4
4 X 10-6
2.8 X 10 -8
4.8 X 10-8
Climate change
Very difficult to predict future
Many complex, interdependent factors
Poorly understood relationships
Predict local weather accurately?
Predict massive climatic change?
Worst case scenario
Worst Case Predictions:
CO2 in atmosphere increase to ~550 ppm by 2050
Temperature increases 6°C
Polar icecaps shrink
Oceans rise 15 feet (150 if E Antarctic falls in)
– Low countries, islands, cities swamped
– 100+°F days in Dallas: 19 increases to 87
– US farmland dries up, Canada thaws out
– Mosquitoes, tsetse flies spread disease
Has the greenhouse effect
already started?
Assess the following statements:
Carbon dioxide contributes to an elevated global
Concentration of carbon dioxide has been increasing over
the past century
The increase in atmospheric carbon dioxide over the past
century is a consequence of human activity
There has been an increase in average global temperature
during the past century.
Carbon dioxide and other gases generated by human activity
are responsible for this temperature increase
The average global temperature will continue to increase as
anthropogenic emissions of greenhouse gases increase.
What can be done?
Those that answer this question can be
categorized into one of three
Must act NOW!
Study it more.
Don’t act b/c it is inevitable …
“Must act Now”
Dr. Stephen Schneider (Stanford)
“… Is this nature being perverse or is it us?
The only way to prove for sure is to hang
around another 10, 20, or 30 more years,
when the evidence would be
overwhelming. But in the meantime, we’re
conducting a global experiment. And we’re
all in the test tube. “
Source – New York Times, December 1997
Further Study
William O’Keefe, CEO of the American
Petroleum Institute
“ I do not agree that it’s a foregone
conclusion that there’s going to be significant
climate change if we don’t take dramatic
action now. We also have to reduce the
scientific uncertainties. We should not base
policy on worst-case scenarios.”
Dr. Michael Oppenheimer,
Environmental Defense Fund
“Scientific uncertainties, which are
substantial, of course, are not a reason
to put off action. In fact, we have only
one Earth to experiment on.”
In contrast to the above mentioned groups –
there are activists – do something NOW and
do it FAST!
Add sulfate aerosols in the atmosphere – Mt.
Pinatubo in 1991
Fertilize southern oceans in with Iron to increase
growth of phytoplankton
MIT scientists propose capturing CO2 and pumping
it into the ocean depths.
Princeton Scientists – pump CO2 underground
What can you do?
Human actions may have long term global
Impact may take decades to reverse
Actions require knowledge, thought,
compassion, wisdom
Even in the absence of threats like global
warming, solutions to this problem would
result in sound, prudent, and responsible
stewardship of our planet.