Methane's role in global warming underestimated

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Methane's role in global warming underestimated

Postby Wilberforce » Fri Oct 30, 2009 10:40 pm

Methane's role in global warming underestimated
By Dan Vergano, USA TODAY

Greenhouse gas calculations blame carbon dioxide too much for global warming, and methane too little,
suggest researchers Thursday.

In the journal Science, a team led by Drew Shindell of the NASA Goddard Institute for Space Studies in
New York finds that chemical interactions between greenhouse gases other than carbon dioxide cause
more global warming than previously estimated by the Intergovernmental Panel on Climate Change
and other efforts.

"The total amount of warming doesn't change, just the balance of gasses behind it," Shindell says.

The world's climate warmed an average about 1.3 degrees Fahrenheit from 1906 to 2005, very likely
due to industrial greenhouse gases, the IPCC concluded in 2007, adding that carbon dioxide is "most
important" greenhouse gas. Methane is a greenhouse gas produced by lanfills, agriculture and some

In the study, Shindell and colleagues added chemical interactions between aerosols and greenhouse
gases such as methane and carbon monoxide to a century-long model of climate change. They wanted
to see the effects on each gas's "Global Warming Potential," or individual contribution to global warming.

Methane played a bigger role than expected, suggesting that climate treaties such as the 1997 Kyoto
Protocol need to consider it more carefully, the study says.

Greenhouse gases are transparent to sunlight, but retain heat in the atmosphere, raising global average
temperatures. Burning fossil fuels, deforestation and other human activities have raised greenhouse gas
levels to historic values in the last three centuries.

"There is no way, other than aggressive geoengineering, to come close to meeting the world leaders?
goal of overall warming not exceeding (3.6 degrees Fahrenheit) above preindustrial (levels) without
focusing on BOTH carbon dioxide and non-carbon dioxide emissions," says Michael MacCracken of the
Climate Institute, by email. "This is not an either-or choice — we must do both to have any chance at all."

Because non-carbon dioxide gasses also cause air pollution, MacCracken and Shindell both suggest that
politicians may embrace limiting those emissions in developing nations more quickly than carbon dioxide
ones. China has about 750,000 air-quality-related deaths annually according to the World Health
Organization, for example.

In December, representatives of 192 nations head to Copenhagen to work on an international agreement
to limit emissions. On the international front, "getting priorities right on the non-carbon dioxide
greenhouse gases has some real value," says MacCracken, a former Clinton-administration climate
scientist. If negotiations keep stalling on carbon dioxide emissions debate, then "all of our efforts on the
non-carbon dioxide greenhouse gases won?t make much difference," he says. "There needs to be a deal
and, in my view, cutting non-carbon dioxide greenhouse gases and soot can be a helpful bridge to getting
an agreement."

Current emissions of aerosols actually cool the atmosphere an average about 1.26 degrees Fahrenheit,
notes aerosol expert Joyce Penner of the University of Michigan. "So changing aerosol concentrations
through changing greenhouse gas emissions is certainly a factor that needs to be considered," Penner
says." I think that what is needed here is a holistic approach to climate control that takes into account
all the factors that influence climate change (including the present day "protection" by aerosol emissions)."

source ... ming_N.htm
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Re: Methane's role in global warming underestimated

Postby Durand » Thu Sep 22, 2011 8:27 pm

thank you for you article
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