NASA - National Aeronautics and Space Administration

One ingredient in air pollution seen in the "smog" from large cities may also play a big role in changing temperatures far to the north in the cold expanse of the Arctic.

In a global assessment of the impact of ozone on climate warming, scientists at the NASA Goddard Institute for Space Studies (GISS), New York, evaluated how ozone in the lowest part of the atmosphere (tropospheric ozone) changed surface temperatures over the past 100 years. Using the best available estimates of global emissions of the various gases that produce tropospheric ozone, the GISS computer model study reveals how much this single air pollutant and greenhouse gas has contributed to warming in specific regions of the world.

Right image: As much as one-third of the observed warming over the Arctic (shown in red) during 1990 was caused by ozone pollution low in the atmosphere. Click on image for high resolution. Credit: NASA/Lori Perkins

According to this new research, ozone was responsible for one-third to half of the warming observed in the Arctic during winter and spring. Ozone moves through the atmosphere from the industrialized countries in the Northern Hemisphere to the Arctic quite efficiently during these seasons. It is formed from several other chemicals also found in the atmosphere near to Earth's surface that come from both natural sources and human activities.

Ozone plays several different roles in the Earth’s atmosphere. In the high-altitude region of the stratosphere, ozone acts to shield the planet from harmful ultraviolet radiation. In the lower portion of the atmosphere (the troposphere), ozone can damage human health, crops and ecosystems. Ozone is also a greenhouse gas and contributes to global warming.

The new results identify an unexpected benefit of air pollution control efforts worldwide, according to lead author Drew Shindell. "We now see that reducing ozone pollution can not only improve air quality but also have the added benefit of easing climate warming, especially in the Arctic."

The findings have been accepted for publication in the American Geophysical Union's Journal of Geophysical Research-Atmospheres.

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Stephen Cole
Goddard Space Flight Center