Still, at least half the warming remains attributable to global warming caused by rising carbon dioxide emissions.
Greenland and parts of neighboring Canada have experienced some of the most extreme warming since 1979, at a rate of about 1 degree Celsius per decade, or several times the global average. inghua Ding, a UW research scientist in atmospheric sciences, said they need to understand why in the last 30 years global warming is not uniform.
Ding said superimposed on this global average warming are some regional features that need to be explained.
The study used observations and advanced computer models to show that a warmer western tropical Pacific Ocean has caused atmospheric changes over the North Atlantic that have warmed the surface by about a half-degree per decade since 1979.
Co-author David Battisti, a UW professor of atmospheric sciences said the pattern of the changes in the tropical Pacific that are responsible for remarkable atmospheric circulation changes and warming in Greenland and the Canadian Arctic are consistent with what we would call natural variability.
Co-author John "Mike" Wallace, a UW professor of atmospheric sciences, said researchers say it's not surprising to find the imprint of natural variability in an area famous for its melting ice. In many of the fastest-warming areas on Earth, global warming and natural variations both contribute to create a "perfect storm" for warming.
The paper has been published in the journal Nature.