Walden, who is a UI geography professor, said while taking measurements they discovered the ice sheet covering Greenland was melting rapidly, which contributes to the rise in sea level.
"We were there just to measure atmospheric and cloud qualities, and we just happened to be there at the right time to measure this melting event that occurred last July," he said.
He said this is an event that has not occurred at Summit, a field research station supported by the National Science Foundation that sits at about 10,000 feet above sea level, since 1889.
"Summit is at the top ... that's the highest elevation at the ice sheet," Walden said.
But, he said, it was their ability to determine what caused the ice melt that made Nature, a top scientific journal, decide to publish their article and put it on the cover.
This is the first time Walden has been published in Nature. He said that's a prestigious and difficult task to accomplish even without being considered for the cover. It took two rounds of peer review to be accepted, and then they were asked for cover art submissions, he said.
"I kind of did some shouting and some dancing," Walden said of his reaction to the cover. "I thought we had a good shot because it's a great picture."
Walden said the photo shows what they were talking about in their article and what caused the melt - just the right amount of cloud thickness and type.
Walden said because they were in Greenland at the time of the melting, they had great data which could then be input into a model to test cloud thickness to determine if it was a factor.
"The model and the measurements agreed and then we were able to determine the clouds were key," he said.
The clouds, Walden said, were the perfect thickness because they were thin enough to allow sunlight to pass through but thick enough to trap heat on the surface. Not only that, he said, it was a water cloud that existed below freezing, which are called super cool water clouds and occur when the pure water droplets are unable to freeze to something.
Walden said this is significant because scientists have offered a range of projections for how quickly and how much the Earth is expected to warm. Based on that, they have a similar range of projections for how quickly Greenland's ice sheet would melt. Today, the ice pack is melting at the rate of the worst projection.
"The ice melt of Greenland is contributing significantly to sea water rise," he said.
UI doctoral student Chris Cox was also a co-author of the article.
Walden, who is originally from around Kalispell, Mont., said he has only been to the Arctic for research twice. Before 2006 he had only been to Antarctica. He said he really got interested in the Earth's atmosphere when he was a graduate student at the University of Washington and had the opportunity to do research at the South Pole.
"I've been hooked ever since," he said.
Information from: The Moscow-Pullman Daily News