NASA's Remote Sensing Systems have measured a .36 degree Fahrenheit temperature increase in the last 35 years, but that increase occurred between 1979 and 1998 and has been decreasing since then. The arctic ice cap actually increased from 2012 to 2013. Documented records exist of warming and cooling periods over the past 5,000 years. On Greenland, archeologists have uncovered abandoned Viking settlements below the country's now frozen tundra and the remains of an ancient forest far above the current natural tree line. In Montana's Glacier National Park tree stumps dated between 1,400 and 2,350 years ago are emerging from under the Mendenhall glacier.