MELBOURNE, May 4 (UPI) -- An Australian study suggests melting sea ice as a major cause of arctic warming in the past two decades.
University of Melbourne researchers led by James Screen said the increased arctic warming was due to positive feedback between sea ice melting and atmospheric warming.
"The sea ice acts like a shiny lid on the Arctic Ocean," Screen said. "When it is heated, it reflects most of the incoming sunlight back into space. When the sea ice melts, more heat is absorbed by the water. The warmer water then heats the atmosphere above it. What we found is this feedback system has warmed the atmosphere at a faster rate than it would otherwise."
The scientists said their findings conflict with previous hypotheses that warmer air transported from lower latitudes toward the pole, or changes in cloud cover, are the primary causes of enhanced arctic warming.
The arctic region has experience the fastest warming of any area on Earth, partly caused by increasing human greenhouse gas emissions, Screen said. At the same time, the arctic ice has been declining dramatically.
Ian Simmonds, a professor at the university's School of Earth Sciences and co-author of the research paper, says the findings are significant.
"It was previously thought that loss of sea ice could cause further warming," Simmonds said. "Now we have confirmation this is already happening."
The study appears in the journal Nature.
