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The Boston Globe

By John Donnelly, Globe Staff  |  December 5, 2007

WASHINGTON - As world leaders meet in Bali this week to find new ways to
battle global warming, some of the nation's top climate change
scientists yesterday argued that there's little concrete evidence
connecting global warming to the spread of infectious diseases, while
others said the link is crystal clear.

The debate before an Institute of Medicine panel on global health,
occurring less than a mile from the US Capitol building, was far from an
academic exercise. A similar review in 2001, which found little
conclusive data that climate change is adversely affecting human health,
was among the arguments the Environmental Protection Agency used in
denying states the ability to curb emissions from new motor vehicles.

Now, after the US Supreme Court ordered the EPA to review that decision
earlier this year, the scientific disagreement yesterday - particularly
the clash between an academic from Harvard University and one from the
University of Pittsburgh - paralleled an ongoing political battle
between the Bush administration and several states, including Massachusetts

Donald S. Burke, dean of Pittsburgh's Graduate School of Public Health,
noted that the 2001 study found that weather fluctuation and seasonal
variability may influence the spread of infectious disease. But he also
noted that such conclusions should be interpreted with caution.

"There are no apocalyptic pronouncements," Burke said. "There's an awful
lot we don't know."

Burke said he is not convinced that climate change can be proven to
cause the spread of many diseases, specifically naming dengue fever,
influenza, and West Nile virus.

But Paul R. Epstein, associate director of the Center for Health and the
Global Environment at Harvard Medical School, said clusters of disease
outbreaks spread by water, mosquitoes, and rats could clearly be traced
to global warming.

"Extreme weather changes have the biggest effect on the environment and
on human health," he said in an interview after his talk. "It's about
heat waves, flooding, extreme storms - all of those affect human health
and are related to climate change."

Epstein said those who "just look at specific diseases can miss the
broader picture. If you look at ecological systems, water systems, the
extreme weather, the range of wildlife . . . or more profoundly
everything that supports a health system, then you can see the linkages.
Scope is really important when you look at this."

The global health specialists, though, heard about the spread of several
diseases, including an outbreak of chikungunya fever in northern Italy
recently. The disease, normally found in Africa and Asia, is transmitted
by mosquitoes and can cause fever, chills, vomiting, and nausea.

Jean-Paul Chretien, the Defense Department's coordinator of overseas
laboratories, said there was "anecdotal evidence" from Italy that the
mosquito population had risen significantly, this year, perhaps because
of a warmer-than-normal summer.

He said an earlier outbreak of chikungunya fever on Kenya's coast had a
more documented link to climate change. Weather patterns caused by the
atmospheric phenomenon La Niña contributed to a drought in east Africa
in 2004. Because of a shortage of fresh water, people rarely emptied
buckets around their homes, giving mosquitoes an ideal breeding ground
of standing water.

"An outbreak like that is from a convergence of factors, and climate is
one of them," Chretien said in an interview.

While scientific proceedings in Washington often are related to
political developments, the forum yesterday was unusually close to the
politics of the day.

In addition to the Bali gathering and the EPA deliberations, the US
Senate Environment and Public Works Committee said it would debate
amendments today on a global warming bill that would create a "cap and
trade" system designed to restrict US greenhouse gas emissions.

Also, the House today is expected to vote on an energy bill, which calls
for increasing fuel economy standards for new cars and trucks to an
average of 35 miles per gallon by 2020 - a provision that not only saves
fuel, but could cut carbon dioxide emissions.

Representative Edward J. Markey, chairman of the House Select Committee
on Energy Independence and Global Warming, said he expects the bill to
pass today; the Senate is expected to debate the energy bill next week.

Markey said he has no doubt that climate change is affecting human health.

"It leads to the migration of animals, who are bearing disease, and
brings them close to population areas that they otherwise had not been
exposed to," he said. "Before climate change, mosquitoes were not
present in Nairobi because of the elevation. But as it warms, these
insects are moving higher and they bring malaria and other diseases with