For how long have humans polluted the Arctic? Thirty years? Forty?

According to research published by two University of Utah scientists, the answer is at least 138 years, and possibly much longer. The study may improve understanding of global climate change.

"Perhaps there was significant warming of the Arctic even 100 years ago or so," said Tim Garrett, assistant professor of meteorology at the U.

Garrett and Lisa Verzella, former undergraduate students in the department of meteorology, researched the question of air pollution in the Arctic and found that particulates from industrial sources were observed by an Arctic explorer in 1870. The findings of Garrett, lead author, and Verzella are to be published in the March edition of the Bulletin of the American Meteorological Society under the title "An Evolving History of Arctic Aerosols."

In earlier work, Garrett attempted to estimate the effect of haze on the Arctic climate, particularly its effect on clouds. He showed that aerosol pollution blows northward from developed countries and into the Arctic. The pollution affects the clouds in a way that warms the arctic surface and is involved in melting the region's ice. It is most prevalent in the winter and spring.

When air pollution in the Arctic was measured in detail during the 1970s by Glenn Shaw of the University of Alaska, he said, "There was a huge amount of skepticism that this could possibly be true, that the Arctic, which is such a remote place, would have high levels of aerosol pollution."

The amount Shaw measured was equivalent to air pollution in a city at more temperate climes.

Studies continued through the 1990s, and Shaw found reports from Air Force pilots who had carried out reconnaissance flights in the Arctic in the 1940s and '50s. They had discovered haze at high altitudes, but the reports had gone largely unnoticed until Shaw dug them up.

Garrett wondered if pollution had been observed in the Arctic for a long time. "There's been pollution in the mid-latitudes for much longer than the 1950s," he decided. Could pollution from industrial facilities have drifted north "even as early as the 1800s?"

He decided to dig up records by famous Arctic explorers and check if pollution is mentioned in them.

Verzella, who was a student of his, took on the project as an undergraduate. "She did most of the groundwork for this, and we dug up all sorts of old records, old journal articles."

Several articles about the Arctic dating to the late 19th century referred to haze of the type now known to be pollution.