ANNE THOMPSON, reporting:
It can be seen billowing from smoke stacks, diesel engines and cooking stoves in villages
and cities around the world. Black carbon, small soot-like particles that are produced
whenever fossil fuels or other organic substances are incompletely burned.
Dr. VEERABHADRAN RAMANATHAN (Scripps Institution of Oceanography): One of the major sources
of black carbon is indoor cooking with biomass fuels, firewood, cow dung, crop residues,
is a major source of fuel and amazingly roughly half the worlds population, about three billion
depend on these fuels.
THOMPSON: According to the World Health Organization, black carbon causes an estimated 1.5 million
deaths per year due to respiratory ailments and other diseases. But beyond the public
health implications, black carbon also has serious impacts on the environment.
Dr. Veerabhadran Ramanathan at the Scripps Institution of Oceanography in San Diego calls
it one of the leading contributors to global warming, after carbon dioxide.
RAMANATHAN: The reason were thinking about black carbon and we are worried about it is
that its the most efficient absorber of sunlight, thats why its blackish.
THOMPSON: In the air, these tiny black carbon particles absorb energy from the sun. This
energy gets converted to thermal energy, which warms the atmosphere. Inside his lab, Ramanathan
compares black carbon samples gathered from different regions of the world.
RAMANATHAN: If you think thats dark, this is that filter collected next to the cooking
stove of a women cooking thats exactly what she is breathing.
THOMPSON: To track the concentration of black carbon in the air and the amount of sunlight
it absorbs, he also flies unmanned aerial vehicles, or UAV's, directly into polluted
air. With this information, Ramanathan can get a global picture of black carbon and how
it spreads around the world, sometimes hundreds, even thousands of miles from its source.
RAMANATHAN: To my mind what this shows, each one of us is in somebody elses backyard. So
were not going to solve this problem by pointing fingers.
THOMPSON: But the problem doesn't end there. As these particles get knocked out of the
atmosphere by falling rain or snow they accumulate on mountaintops and glaciers, with additional
negative impacts.
Dr. JOE MCCONNELL (Desert Research Institute): If you add just the tiniest amount of black
carbon to that fresh snow, it will change the amount of energy that it absorbs, cause
it to warm more quickly and eventually melt more quickly.
THOMPSON: This process is called the 'Albedo Effect'. As the soot darkens the bright white
snow covering glaciers and ice caps, it absorbs solar energy, grows warmer and contributes
to melting the ice cap causing it to shrink.
Dr. Joe McConnell, studies this effect in the seasonal snow pack in the Sierra Nevada
Mountains in the western United States. By measuring the temperature of the snow and
the distribution of black carbon and other particles in it, McConnell and his team can
find out how much black carbon contributes to snow melt.
MCCONNELL: And theres our sample.
THOMPSON: In the lab, McConnells research goes even deeper. He studies ice cores that
span decades, like this one collected from Greenland.
MCCONNELL: This particular section of ice is about 130 years old, this is snow from
the 1870s or so.
THOMPSON: Using a special instrument for melting ice cores, McConnell measures individual black
carbon particles to find out how, and in some cases where black carbon was produced decades
ago.
MCCONNELL: Right now were at about 1850, so this is about 160 years ago this snow fell,
so these bumps are primarily coming from forest fires that happened 160 years ago.
THOMPSON: With this data, McConnell supplies global climate modelers with more accurate
histories of black carbon and other emissions.
MCCONNELL: This is the most recent decade, 2000-2010, and you can see most of the emissions
are coming from this part of Asia.
THOMPSON: But of all the causes of global warming, black carbon might be the easiest
problem to fix because, unlike carbon dioxide, it stays in the atmosphere for only a short
time.
RAMANATHAN: The most appealing part of targeting black carbon to reduce global warming is its
lifetime. It stays in the air less than a few weeks so what that means is that when
you initiate a policy to condemn black carbon today, theyre gone two weeks from now.
THOMPSON: Ramanathan has started a program, called Project Surya, distributing solar powered
lanterns, and cleaner, more efficient cooking stoves to families.
One of his first test areas is a village in the Uttar Pradesh region of northern India.
His goal is to not only reduce global warming, but also to create a more healthy environment
for people who rely on these cooking stoves.
RAMANATHAN: So Surya is a scientific intervention project. Its also a demonstration to show
that if these women could be given better stoves, which cuts on emissions it not only
helps them, it helps the region and helps the planet.
THOMPSON: Paving the way for a cleaner, brighter and healthier future for the planet and its
people.