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Satellite image of particulate pollution over Beijing |
Roughly half the aerosols that affect air quality and climate change in North America may be coming from other continents, including Asia, Africa and Europe, according to a new study by researchers at the University of Maryland, College Park, NASA Goddard Space Flight Center, University of Maryland at Baltimore County and the Universities Space Research Association.
Atmospheric
particles can travel thousands of miles downwind and impact the environment in
other regions, found lead researcher Hongbin Yu of the University of Maryland,
and his team in a report published in the August 3, 2012 issue of the journal Science.
This could offset emission controls in North America and suggests there are
more factors affecting domestic pollution than the Environmental Protection
Agency has accounted for.
"People have
been concerned about how an emerging Asian economy and increased manmade
pollution will influence North American air quality and climate, but we found
that dust makes large contributions here," explained Yu, an associate research
scientist in UMD's Earth System Science Interdisciplinary Center (ESSIC).
"So we cannot just focus on pollution. We need to consider dust."
The study, which
provides the first satellite-measurement-based estimate of the amount of
airborne particles that come to North America from overseas, shows this
migrating dust usually comes in at high altitudes and in the U.S. is most
likely to affect upper atmospheric conditions.
Most of the
pollution migrating into the North American atmosphere is not industrial
emissions but dust from Asia, Africa, and the Middle East, , Yu found. Out of
the total annual accumulation of foreign aerosols, 87.5 percent is dust from
across the Pacific, 6.25 percent is composed of combustion aerosols from the
same region and 6.25 percent is Saharan dust from across the Atlantic.
The EPA is aware
that foreign pollution affects U.S. air, but it is unclear on the amount of
imported aerosols, Yu said. The study revealed that much of the dust migration
occurs at high altitudes and is unlikely to affect the air we breathe.
However, Yu adds:
"Scientists need to acquire a better understanding of the interactions
between dust and climate."
Current satellite
sensor technology allows scientists to track aerosol plumes across the ocean
and measure their composition and particle characteristics. The
three-dimensional satellite measurements can distinguish dust from other types
of aerosols such as those released from burning biomass and fuel. While dust
and combustion aerosol migration occurs year round, it is heightened in the
spring due to strong seasonal wind patterns and extra-tropical cyclones.
UMD climate
scientist Antonio (Tony) Busalacchi, who is chairman of the Joint Scientific
Committee for the World Climate Research Programme and chairman of the Board on
Atmospheric Sciences and Climate of the U.S. National Academy of
Sciences/National Research Council, says one of the most interesting points Yu
and his coauthors make in their study is that even a reduction of industrial
emissions by the emerging economies of Asia could be overwhelmed by an increase
in dust emissions due to changes in meteorological conditions and potential
desertification.
"Over the
course of time climate, human influence on the environment, and dust emissions
have been inextricably linked," notes ESSIC Director Busalacchi, who was
not involved in the study. "One need only look at the Dust Bowl of the
1930's to see this. With ever expanding drought conditions due to climate
change, we can expect trans-boundary transport of dust aerosols to increase in
the future"
Lorraine
Remer, Mian Chin, Huisheng Bian, Qian Tan, Tianle Yuan and Yan Zhang also
contributed to the study, Aerosols from Overseas Rival Domestic Emissions over
North America.
Story Source:
The above story is reprinted from materials provided by University of Maryland. The original article was written by Evelyn Rabil.Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Journal Reference:
- H. Yu, L. A. Remer, M. Chin, H. Bian, Q. Tan, T. Yuan, Y. Zhang. Aerosols from Overseas Rival Domestic Emissions over North America. Science, 2012; 337 (6094): 566 DOI: 10.1126/science.1217576
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