Science, politics,
speculation all key in assessing climate change
BY DAVID F. SALISBURY
Could global warming throw
the world's climate into another Ice Age?
According to Donald
Kennedy, the Bing Professor of Environmental Science,
that key question has not received much attention in
public discussions about humanity's growing impact on the
climate and what to do about it.
Kennedy raised the
possibility on Oct. 20 at a presentation for the advisory
council of the Institute for International Studies. He
and Robert B. Dunbar, professor of geological and
environmental sciences, briefed the council on the
underlying science, while Argentinean Ambassador Raúl
Estrada Oyuela, economics Professor Lawrence Goulder and
law Professor Thomas Heller filled the group in on some
of the political, economic and legal dimensions.
"Human influence on
the planet has assumed the scale of a very large
experiment for which we don't know the conclusion,"
said Kennedy, president emeritus of Stanford and
co-director of the university's Center for Environmental
Science and Policy. "On the one hand, it is a great
success, but, on the other hand, it has created some new
risks."
There is no question that
the greenhouse effect is real, Kennedy said. Gases in the
atmosphere trap the longer wavelength solar rays that
contribute to heating. While political debate has
centered on carbon dioxide -- which is most closely
associated with human activities, and the most
significant new contributor to the effect -- it is
important not to forget that there are other, natural
greenhouses gases like methane and, above all, water
vapor that have a much greater effect, Kennedy said.
Current controversy
centers on whether the recorded increases in carbon
dioxide have altered the climate. There is now a
scientific consensus that the global average temperature
has increased by about one degree Fahrenheit in recent
years. This has been enough to alter bird and fish
distributions and the composition of marine animals in
the intertidal regions of North America, but not enough
to have had much of an economic impact. How much of this
temperature rise is due to human activities and how much
is due to a natural cycle is unclear, Kennedy said.
The history of climate
change may give some clues about what to expect. Ice
cores extracted from Greenland glaciers provide a record
of average annual temperatures that reach back for
115,000 years. This record shows that the world climate
can shift from a warm period to an ice age abruptly, in a
matter of decades. The record also shows that the climate
for the last 10,000 years has been unusually mild. Other
climatic epochs have been much less favorable for human
activity, he said.
"This raises an
important question. Is there a threshold that we will
pass that will throw us into a more unstable regime and
will this cause a dramatic cooling?" Kennedy asked.
There is a good chance
that we will be able to see these changes coming, Dunbar
reported. In the last 18 months, scientists have set up a
worldwide operational system of climate prediction. This
became possible when climatologists realized that El
Niño and three other similar air-ocean systems control
between 50 to 70 percent of the total climate
variability. The other three, which are not nearly as
well known, are the North Atlantic Oscillation, the
Pacific Decadal Oscillation and the Pacific South
American Pattern.
The four are "a
series of drummers that are each drumming to their own
beat. Every now and then two and three get together and
compose their own symphony, but they end up coming back
together to orchestrate features of the global climate
system," Dunbar said.
El Niño, for example,
affects weather patterns over 30 percent of the globe,
ranging from South Africa to Indonesia to the Americas.
During El Niño years, long hot summers in South Africa
can reduce crop yields by as much as two-thirds. It
suppresses hurricane formation in the Atlantic Ocean and
Gulf of Mexico. In Colombia, it is associated with the
increased incidence of malaria.
The other three systems
are similar to El Niño but hold sway in different parts
of the globe and work on longer time scales. The North
Atlantic Oscillation and Pacific Decadal Oscillation, for
example, run alternately hot and cold on a 10-to 20-year
time scale.
Estrada, who is spending
the year at the institute as its Payne Distinguished
Professor, was one of the chief architects of the Kyoto
Protocol. Concluded last December, the protocol asks
industrialized countries such as the United States, Japan
and the nations of Europe to adopt specific goals and
timelines for nationwide reductions of greenhouse gas
emissions. It has now been signed by 55 countries.
One key to the agreement
was the decision to treat developing and developed
countries differently. Developed countries made a
commitment to take the lead and agreed to give financial
and technological assistance to the developing countries
to aid them in meeting their goals. Also, targets for
developing countries were set leniently enough so that
they can continue to develop by "leapfrogging"
directly to more efficient technologies, Estrada said.
Heller, the Lewis Talbot
and Nadine Hearn Shelton Professor of International Legal
Studies, pointed out that the costs involved in reducing
greenhouse gas emissions can be greatly reduced by what
he calls "where and when flexibility."
"Where"
flexibility is giving people the ability to make
reductions where they are cheapest. "Cost of
reducing carbon emissions varies greatly around the
world, so allowing people to solve this problem where it
is cheapest makes it much more economical," Heller
said.
"When"
flexibility, on the other hand, gives people the ability
to determine when they are going to make improvements. In
a given factory, for instance, it is much cheaper to
install lower-emissions machinery when the old machinery
is worn out.
Finally, Goulder,
associate professor of economics, explained that the most
cost-effective approaches to greenhouse gas reduction
tend to be the least politically palatable. Economic
studies indicate that a "carbon tax" that
increases the cost of fossil fuels would be the most
effective. Also, it allows the possibility of reducing
the overall cost of the tax by reducing other taxes, like
income taxes.
"Studies indicate
that this wouldn't be a free lunch, but it may be a lunch
worth buying," Goulder said. The big political
problem is that such a tax would hit the fossil fuel
industry very hard, so the industry is strongly opposed
to it. SR
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