Clouds that are more 'sensitive' to pollution are speeding up Arctic warming

Scientists are paying close attention to the blanket of clouds thatinsulatethe Arctic and play a major role inwarming up the North.

Researchers from the University of Utah published a new study Wednesday that suggests Arctic clouds are between two and eight times more sensitive to pollution than clouds in other parts of the world.

Pollutants in the air from Europe and China modify the physical structure of water droplets in Arctic clouds. The effect of that is to warm the earth in a similar way to a down jacket, or adding an extra blanket on a cold night.

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The study found this effect is more pronounced in the Arctic than in clouds closer to the equator.

"Clouds anywhere, but particularly in the Arctic can become more effective blankets, warming the surface when they become more polluted," explained Tim Garrett, an atmospheric scientist and lead researcher on the project.

"In the Arctic, clouds are thin to begin with so they are particularly susceptible to pollution, becoming more effective blankets," Garrett said. "That makes the Arctic night warmer than it would be otherwise."

It's not clearwhy Arctic clouds act this way, but Garrett says it could be because Arctic air is generally more stable than the tropics or mid-latitudes.

"One of the big things that controls clouds is the weather," Garrett said. "If the weather is relatively still, my suspicion is that the pollution that comes from other places can have a larger impact than where the clouds are more active."

Governments and companies looking to increase industrialization in the Arctic should take these findings into consideration since any local increase in air pollutants would likely have a similar effect, Garrett said.

Changing Arctic has 'huge impact'

For Patrick Taylor, an atmospheric scientist at NASA, these results are not surprising. He published another study last summer that looked at how clouds interact with melting sea ice. It suggests sea ice has less of an effect on cloud formation than previously thought.

Studying Arctic clouds has become an important part of studying climate change, especially over the past decade, Taylor said.

"Climate models show a difference between 2 C and 6 C," Taylor said. "The reason that difference is so large is because of cloud cover."

If there is less cloud cover, warming could be less pronounced, Taylor explained. But if cloud cover increases, the earth could warm even further, meaning scientists will continue studying this subject.

"The Arctic acts as the globe's refrigerator, helping regulate the temperature," Taylor said. "Even though geographically it's smaller than the tropics, changes in the Arctic can have a huge impact."