[Vision2020] Burning Fuel Particles Do More Damage to Climate Than Thought, Study Says

[Art Deco]

  [image: The New York Times] <http://www.nytimes.com/>

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January 15, 2013
Burning Fuel Particles Do More Damage to Climate Than Thought, Study Says By
ELISABETH ROSENTHAL<http://topics.nytimes.com/top/reference/timestopics/people/r/elisabeth_rosenthal/index.html>

The tiny black particles released into the atmosphere by burning fuels are
far more powerful agents of global
warming<http://topics.nytimes.com/top/news/science/topics/globalwarming/index.html?inline=nyt-classifier>than
had previously been estimated, some of the world’s most prominent
atmospheric scientists reported in a
study<http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50171/abstract>issued
on Tuesday.

These particles, which are known as black carbon
<http://www.epa.gov/blackcarbon/> and are the major component of soot, are
the second most important contributor to global warming, behind only carbon
dioxide, wrote the 31 authors of the study, published online by The Journal
of Geophysical Research-Atmospheres.<http://onlinelibrary.wiley.com/journal/10.1002/%28ISSN%292169-8996>

The new estimate of black carbon’s heat-trapping power is about double the
one made in the last major report by the United Nations’ Intergovernmental
Panel on Climate
Change<http://topics.nytimes.com/top/reference/timestopics/organizations/i/intergovernmental_panel_on_climate_change/index.html?inline=nyt-org>,
in 2007. And the researchers said that if indirect warming effects of the
particles are factored in, they may be trapping heat at almost three times
the previously estimated rate.

The new calculation adds urgency to efforts to curb the production of black
carbon, which is released primarily by diesel engines in the industrialized
world and by primitive cook stoves and kerosene lamps in poorer nations.
Natural phenomena like forest fires also produce it.

Black carbon is already a central target of one of the few international
climate initiatives championed by the United States, the Climate and Clean
Air Coalition to Reduce Short-Lived Climate
Pollutants<http://www.unep.org/ccac/>,
which has been supported by Secretary of State Hillary Rodham Clinton. The
program seeks to reduce the production of black carbon to combat both
climate change and air pollution and respiratory disease on the
ground<http://www.nytimes.com/2009/04/16/science/earth/16degrees.html?pagewanted=all>.


Although some scientists have long believed that black carbon is a major
force in climate change, the vast majority of previous mathematical models
had predicted that the particles had only a modest impact. That view should
now change, said Mark Z. Jacobson, an atmospheric scientist at Stanford
University and one of the study’s authors, calling the old models “overly
simplistic.” He said that many of his co-authors had previously hewed to
the lower estimates.

Veerabhadran Ramanathan, <http://www-ramanathan.ucsd.edu/> a professor of
climate science at the Scripps Institution of
Oceanography<http://sio.ucsd.edu/>in San Diego who has long campaigned
to control black carbon, described the
study as highly authoritative. “The fact that it’s written by a very large
group of modelers gives it enormous credibility,” he said. “It was lonely
before. I’m now glad to be right in the middle.”

The group reached its conclusions after factoring in a new series of
measurements about the amount of black carbon accumulating in the
atmosphere and how much heat from the sun it absorbs. It also took into
account some of the complicated secondary climate effects that occur when
black carbon interacts with chemical, clouds and the earth’s surface.

For example, when black carbon settles on glaciers or Arctic ice, it
renders them darker, and they absorb more heat and melt at a faster rate.

Still, some scientists said the paper mostly underlined how much remained
to be studied about the warming effects of these particles.

“The paper makes a good case that our models are underestimating the
effect, but what it does for me is to underscore all the various
uncertainties,” said Christopher D.
Cappa<http://cee.engr.ucdavis.edu/Faculty/cappa/default.htm>,
an associate professor of environmental science at the University of
California at Davis.

In a study <http://www.sciencemag.org/content/337/6098/1078> published last
year in the journal Science, Dr. Cappa and his colleagues studied
atmospheric samples containing black carbon and
concluded<http://news.ucdavis.edu/search/news_detail.lasso?id=10317>that
they absorbed less sunlight than might be predicted from laboratory
experiments, in part because black carbon is coated with atmospheric
chemicals.

Carbon dioxide, the leading greenhouse gas, remains in the atmosphere for
decades and is distributed nearly uniformly across the earth’s atmosphere.
By contrast, black carbon generally only persists in the air for a week to
10 days, so its presence across the globe is far more variable. And its
effect varies greatly depending on whether it is above or below the clouds,
Dr. Cappa said.

But the short-lived nature of black carbon also makes it a ready target for
efforts to rein in climate change. Any reduction in carbon dioxide
production today will take years to have a tangible effect on global
warming because so much of the gas is already in the atmosphere. But
preventing the release of a ton of black carbon, particularly in just the
right place — say, upwind from a glacier — could have a strong and nearly
immediate impact.

Mrs. Clinton has also been a strong supporter of the Global Alliance for
Clean Cookstoves <http://www.cleancookstoves.org/>, a public-private
partnership whose goal is to replace 100 million primitive stoves in poor
countries with modern versions that produce less black carbon.

On another front, a greater emphasis on black carbon as a warming agent
could affect elements of climate policies in many countries. Most notably,
to meet national fuel
efficiency<http://topics.nytimes.com/top/reference/timestopics/subjects/f/fuel_efficiency/index.html?inline=nyt-classifier>standards,
many carmakers are making more diesel cars because they get
better gas mileage and produce less carbon dioxide.

But diesel engines also produce relatively heavy emissions of black carbon,
Dr. Jacobson said, which partly cancels out the benefit.


-- 
Art Deco (Wayne A. Fox)
art.deco.studios at gmail.com
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