Cleaning Up Black Carbon Provides
Instant Benefits Against Global Warming
The world could buy time to forestall disastrous environmental and
geopolitical climate change effects by using existing technologies to
curb emissions created through diesel and solid biomass fuel burning,
according to an article co-authored by Scripps Institution of
Oceanography at UC San Diego climate and atmospheric scientist V.
Writing in the September/October issue
of Foreign Affairs
magazine with Jessica Seddon Wallack, director of the Center for
Development Finance at the Institute for Financial Management and
Research in Chennai, India, Ramanathan concludes that full
implementation of existing emissions-control technologies could offset
the warming effects of one to two decades of carbon dioxide emissions.
A dedicated effort would not only allow more time for creation of
effective carbon dioxide-reduction regulations but would also have
enormous public health and economic benefits, the authors said.
on reducing emissions of black carbon and ozone precursors is the
low-hanging fruit: the implementation is feasible, and the benefits
would be numerous and immediate,” Wallack and Ramanathan write.
Ramanathan said that he and his
coauthor approached Foreign Affairs
with the concept for the article based on his calculations in a 2008
paper that society has already crossed the threshold at which damaging
effects of climate change are assured. He also approached Wallack, a
policy expert, to suggest ways of presenting the challenge and possible
responses that reach audiences that could implement new regulations and
effect initiatives to make cleaner technologies more accessible.
became clear to me that we have to go beyond just reducing CO2 to hedge
against unmanageable climate change,” Ramanathan said.
carbon and ozone are technologically and politically tractable targets
for immediate policy action,” added Wallack. “The challenge is raising
awareness of their impacts on climate and development and knowledge
about the relatively straightforward steps that can be taken to reduce
Black carbon is a form of carbon that
light and is most commonly produced by people as diesel exhaust or soot
from wood- or dung-burning fires. Ozone is a gas created by reactions
among other gases such as carbon monoxide and methane frequently
produced by human activities. At lower levels of the atmosphere, it is
a greenhouse gas with a warming effect equal to about 20 percent of
that of carbon dioxide.
Both black carbon particles and
ozone gas remain in the atmosphere for periods of only weeks to months,
as opposed to the centuries that carbon dioxide remains in the
atmosphere. The authors argue that mitigation measures targeting black
carbon and ozone would therefore produce immediate climate benefits.
Additionally it would help alleviate damage to respiratory health in
humans caused by black carbon smog, the fourth-leading cause of
premature death in developing countries. Crop yields would be aided by
ozone-removal efforts since the gas damages plant cells and disrupts
Wallack and Ramanathan further point
out that technologies to reduce black carbon and ozone already exist.
The authors cite a finding from an American non-profit research
organization that shows that retrofitting one million tractor-trailers
with diesel particulate filters would produce effects equal to removing
5.7 million cars from the road. The main challenges, according to the
authors, lie in motivating adoption of technologies to reduce diesel
emissions and making technologies to burn biomass fuels more
efficiently accessible around the world. These are more akin to
development challenges than traditional environmental policies.
hope that this will gain a place on the global environmental agenda as
a high priority complement to ongoing efforts to reduce CO2 emissions,”
Wallack said. “More importantly, we hope that greater knowledge of the
climate, health and agricultural benefit of reducing these two
pollutants will reinforce the fact that environmental and economic or
development considerations are often aligned."
“By highlighting the work of Wallack
and Ramanathan, we are introducing Foreign Affairs
readers to black carbon emissions as a serious policy issue to tackle
with potentially dramatic near-term results,” said Managing Editor
Ramanathan said that these mitigation
could serve to hedge against the full effects of global warming caused
by greenhouse gases. They will also offset the acceleration of global
warming that can occur when the atmosphere is cleaned of reflective
particles such as sulfates from coal combustion that have an
atmospheric cooling effect.
Diesel exhaust and cooking with
biomass fuels both have net warming effects, though the magnitude of
biomass burning’s warming effect is not well understood. Ramanathan is
currently studying the net warming effect of biomass burning as part of
Project Surya, an effort to measure the effect of replacing traditional
cooking methods in rural India with cleaner-burning alternatives.
Wallack and UCSD Rady School of Business Professor Vish Krishnan are
also participating in Project Surya to identify ways to remove
bottlenecks to larger-scale adoption of technologies for cleaner
burning of renewables.
“Our finding provides a tremendous
incentive to help the over 3 billion people who live on less than $2 a
day and are forced to cook and heat their homes with biomass fuels such
as dung, crop residues and firewood,” Ramanathan said.