Wood Smoke/black Carbon Soot: a Major Cause of Global Warming

In the frenzied search for solutions to the globalthat wood smoke’s fine particulates thin
warming crisis, climatologists, policy makers andclouds. And as total airborne particulates increase,
other concerned environmentalists havecloud cover decreases, allowing more sunlight to
overlooked one of the leading causes of risingreach the earth.  According to Ramanathan,
temperatures around the globe—soot---theapproximately 35 percent of black carbon in the
black residue that coats fireplaces and darkensglobal atmosphere comes from China and India. 
vehicle exhaust.  Black carbon soot may in factYet per capita emissions of black carbon soot
be the second largest contributor to globalfrom the United States and some European
warming next to the greenhouse gas carboncountries is still comparable to those from Asia.
dioxide. Ramanathan's research also found that the
According to Stanford environmental engineeringwarming effects of black carbon smog appear to
Professor Mark Z. Jacobson, “Soot, or blackbe accelerating the melt of Himalayan
carbon, may be responsible for 15 to 30 percentglaciers, leading to early drying of a major
of global warming, yet it is not even considered insource of drinking water for billions of people
any of the discussions about controlling climatethroughout Asia.
change.” (“Nature”, ScienceDaily, Feb. 
9, 2001).  Jacobson also observed that humanThe International Global Panel on Climate Change
beings produce most of the soot particles that(IGPCC) agreed that black carbon soot is a major
pollute the atmosphere.  He maintains that sootcontributor to global warming
consists primarily of elemental carbon and that 90The 2007 Nobel-winning IGPCC panel of
percent of it comes from the consumption ofapproximately two thousand scientists concluded
fossil fuels (particularly coal, diesel fuel, jet fuel,that black carbon soot has a dire atmospheric
natural gas, kerosene) and the burning of woodwarming effect.  This was significant because
and other biomass.  Jacobson also claims that asoot had previously been unaddressed as a major
worldwide reduction in soot emissions andcontributor to global warming.  Nor had the
controlling biomass burning could quell the alarmingamplification of black carbon’s warming effect
pace of global warming and also reduce ourpreviously been taken into account when mixed
reliance on soot-producing fuels. (with other aerosols, creating additional secondary
Besides its impact on global warming, soot is badfine particulates.
for your health.  The World Health OrganizationStudies of fine particulates from wood smoke in
reports that approximately 2.7 million people dievarious communities
each year from air pollution and that reduction ofAn EPA study cites that “In some
wood and other biomass burning would mitigateneighborhoods, on some days, 90% of the
global warming and would also save lives andparticle pollution is from residential wood
improve people’s health.  burning.” (Jane Koenig and Timothy Larson, A
Other studies have dispelled the myth that burningSummary of Emissions Characterization and
wood and other biomass is “green or carbonNon-Cancer Respiratory Effects of Wood Smoke,
neutral” and that the fine particulates emittedUSEPA DOC #453/R-93-036,1-919-541-0888).
during the combustion process actually hastenA study in two San Jose, California locations
climate change. ( under both “Science” andshowed that wood smoke pollution was 4.4 times
“Global Warming” headings).that of gasoline or diesel fueled vehicles. (“A
The warming effect of black carbon soot is farComparison of Source Apportionments of Fine
greater than previously estimatedParticulate Matter at Two San Jose, CA
Atmospheric scientist V. Ramanathan of theLocations,” from San Jose Speciation Trends
Scripps Institution of Oceanography and UniversityNetwork.)
of Iowa chemical engineer Greg Carmichael foundThe next step
that “black carbon soot, from burning woodBecause the urgency of reducing black carbon
and other biomass, cooking with solid fuels, andemissions cannot be overstated, reducing soot
diesel exhaust has a warming effect in thefrom wood smoke would offer nearly instant
atmosphere three to four times greater thanbenefits in improving atmospheric conditions in the
prevailing estimates.” (Nature Geoscience 1,United States.  It would also offer immediate
221-227 (March 24, 2008).  They calculated thatsocietal and health benefits.  This would facilitate
soot and other forms of black carbon particulatespolitical and regulatory momentum towards
may represent as much as 60 percent of themitigation of black carbon emissions.
current global warming effect of carbon dioxideIt is urgent to advance public awareness of wood
and their findings correlated with similar studiessmoke’s crucial role in global warming with
from Stanford, Caltech, and NASA.education and policy changes.
A simplified explanation for the warming effect is