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March 23, 2005
NASA STUDY FINDS SOOT MAY BE CHANGING THE ARCTIC ENVIRONMENT
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 near the North Pole, such as accelerating melting of sea ice
and snow and changing atmospheric temperatures.
Dorothy Koch of Columbia University, New York, and NASA’s Goddard Institute for Space Studies (GISS), New York, and James Hansen of NASA
GISS are co-authors of the study that appeared in a recent issue of the Journal of Geophysical Research.
“This research offers additional evidence black carbon, generated through the process of incomplete combustion, may have a significant
warming impact on the Arctic,” Koch said. “Further, it means there may be immediate consequences for Arctic ecosystems, and potentially
long-term implications on climate patterns for much of the globe,” she added.
The Arctic is especially susceptible to the impact of human-generated particles and other pollution. In recent years the Arctic has significantly
warmed, and sea-ice cover and glacial snow have diminished. Likely causes for these trends include changing weather patterns and the effects of
pollution. Black carbon has been implicated as playing a role in melting ice and snow. When soot falls on ice, it darkens the surface and accelerates
melting by increasing absorbed sunlight. Airborne soot also warms the air and affects weather patterns and clouds.
Koch and Hansen’s results suggest a possible mechanism behind the satellite- derived observations of Arctic climate change. They found the
timing and location of Arctic warming and sea ice loss in the late 20th century are consistent with a significant contribution from
man-made tiny particles of pollution, or aerosols.
Koch and Hansen used GISS’ General Circulation Model (GCM) to investigate the origins of Arctic soot by isolating various source regions and
types. The GCM employs a lot of different data gathered by NASA and other U.S. satellites to study many environmental factors such as ice cover and
temperature.
The research found in the atmosphere over the Arctic, about one-third of the soot comes from South Asia, one-third from burning biomass or
vegetation around the world, and the remainder from Russia, Europe and North America.
South Asia is estimated to have the largest industrial soot emissions in the world, and the meteorology in that region readily lofts pollution
into the upper atmosphere where it is transported to the North Pole. Meanwhile, the pollution from Europe and Russia travels closer to the
surface.
This study demonstrates the GCMs accurately represent the long-range transport of pollutants, such as those from Southern Asia to the Arctic, that
were observed from aircraft.
During the early 1980s the primary sources of Arctic particulate pollution are believed to have been from Russia and Europe. Those sources have
decreased substantially in the past two decades, but the computer simulations indicate increasing emissions from South Asia have made up for some of
the reduced Eurasian pollution. Koch and Hansen suggest Southern Asia also makes the greatest contribution to soot deposited on Greenland.
NASA sponsored efforts using satellite data and models to assess polar feedbacks constitute an important contribution to the U.S. Climate Change
Science Program. By exploring processes in the Earth?s atmosphere, NASA scientists are seeking answers to how pollutants like soot are changing the
climate of the world around us.
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Contact:
Rob Gutro
Goddard Space Flight Center
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How Polar Ice Reflects Light
This is a conceptual animation showing how polar ice reflects light from the sun. As this ice begins to melt, less sunlight gets reflected into
space. It is instead absorbed into the oceans and land, raising the overall temperature, and fueling further melting. Darker, soot-covered ice
reflects less light as well, part of the warming effect (no audio). Credit: NASA
Black Carbon Emissions
Industrial and biomass black carbon emissions with boxed areas showing regions assumed in the model experiments. Credit: NASA/GISS
Regional Concentrations of Black Carbon
(top left) Annual zonal mean black carbon concentration and percent contributions from regional experiments. Credit: NASA/GISS
Global Reflections
This is a conceptual animation showing how melting ice on land and at sea, can affect the surrounding ocean water, changing both the chemistry and
relative sea level. Click on image to view animation (no audio). Credit: NASA
Soot Particle Under a Microscope
Credit: D.M. Smith, University of Denver
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