Ozone was responsible for one-third to half of the observed warming trend in the Arctic during winter and spring, according to the new research. Ozone is transported from the industrialized countries in the Northern Hemisphere to the Arctic quite efficiently during these seasons. The findings will be published soon in the American Geophysical Union's Journal of Geophysical Research-Atmospheres.

The impact of ozone air pollution on climate warming is difficult to pinpoint because, unlike other greenhouse gases such as carbon dioxide, ozone does not last long enough in the lower atmosphere to spread uniformly around the globe. Its warming impact is much more closely tied to the region it originated from. To capture this complex picture, the GISS scientists used a suite of three-dimensional computer models that starts with data on ozone sources and then tracks how ozone chemically evolved and moved around the world over the past century.

The research was supported by NASA's Atmospheric Chemistry Modeling and Analysis Program.