Researchers Work to Better Understand How Soot Emissions Impact Global Warming

May 07, 2010 By Chriss Swaney

(PhysOrg.com) -- Researchers from Tech, Carnegie Mellon University and the California Institute of Technology are collaborating to study the effects of soot on global warming.

Soot, tiny airborne particles that billow out of diesel trucks and industrial smokestacks, is not only harmful to humans, but may be causing harmful warming effects that could create more severe and hotter temperatures worldwide. Other major sources of black carbon include use of biofuels for cooking and heating in developing countries and .

In a study recently published in , Carnegie Mellon's Peter Adams and colleagues John H. Seinfeld of the California Institute of Technology and Athanasios Nenes of the Georgia Institute of Technology report that controls on soot might not slow global warming as much as previously thought.

Adams, the study's co-author and an associate professor of civil and environmental engineering and engineering and public policy at Carnegie Mellon, said the study focused on atmospheric cloud condensation nuclei (CCN) concentrations, airborne particles that are the seeds upon which cloud droplets form. Clouds that form in polluted air masses with high CCN concentrations tend to reflect more sunlight back into space than their cleaner counterparts. According to the study, if soot particles were cut in half, cloud reflection would decrease to allow an additional 0.13 watts per square meter of sunlight — the equivalent of about 10 billion spread across the United States — to reach and warm the earth.

So, what does this mean for policymakers?

"In some ways, the study doesn't change much. Soot particles are still a big air quality and health problem, and their emissions should be cut for this reason alone," Adams said. "What our study highlights is the competing warming and cooling effects that result from soot emissions, making it hard to say what its net effect is on global temperature. From a global climate standpoint, cutting soot is probably worth a shot but it is not a slam dunk like cutting carbon dioxide and other greenhouse gases. A lot will depend on what kinds of emission sources are targeted and the specific control strategies chosen."

The study has implications for the ongoing climate policy debate about assigning a potential (GWP) to soot, a metric for comparing its climate impact to carbon dioxide. GWP values have been assigned to a wide range of greenhouse gases.

"Our research shows that uncertainties on how clouds will respond to soot controls may make it difficult to define a GWP value appropriate for soot," said Seinfeld, study co-author and the Louis E. Nohl Professor at Caltech.

"And even if its effect on global average temperature is unclear, besides its effects on human health, soot interferes with regional precipitation and circulation patterns, so control of soot should remain on the table," said Nenes, an associate professor of earth and atmospheric sciences and chemical and biomedical engineering at Georgia Tech.

Explore further: Satellite catches lingering remnants of Tropical Depression 9

Provided by Georgia Institute of Technology

3 /5 (2 votes)
add to favorites email to friend print save as pdf

Related Stories

Dirty snow may warm Arctic as much as greenhouse gases

Jun 06, 2007

The global warming debate has focused on carbon dioxide emissions, but scientists at UC Irvine have determined that a lesser-known mechanism -- dirty snow -- can explain one-third or more of the Arctic warming ...

NASA probes the sources of the world's tiny pollutants

Jan 30, 2007

Pinpointing pollutant sources is an important part of the ongoing battle to improve air quality and to understand its impact on climate. Scientists using NASA data recently tracked the path and distribution ...

NOAA takes first broad look at soot from ships

Jul 09, 2008

Tugboats puff out more soot for the amount of fuel used than other commercial vessels, and large cargo ships emit more than twice as much soot as previously estimated, according to the first extensive study of commercial ...

NASA Study Finds Soot May be Changing the Arctic Environment

Mar 23, 2005

NASA continues to explore the impact of black carbon or soot on the Earth's climate. NASA uses satellite data and computer models that recreate the climate. New findings show soot may be contributing to changes happening ...

Recommended for you

NASA sees Tropical Storm Ana still vigorous

57 minutes ago

NASA's TRMM satellite saw that Tropical Storm Ana was still generating moderate rainfall is it pulled away from Hawaii. The next day, NASA's Aqua satellite saw that wind shear was having an effect on the ...

User comments : 0