NASA scientists and the National Snow and Ice Data Center (NSIDC) reported the "extent of sea ice covering the Arctic Ocean" reached a record low this year, the lowest observed since satellite observations of the polar cap began in the 1970s.
In a NASA press release senior NASA research scientist Joey Comiso said decades of gradual thaw led to this years record breaking melt:
"The persistent loss of perennial ice cover, ice that survives the melt season, led to this year's record summertime retreat. Unlike 2007, temperatures were not unusually warm in the Arctic this summer."
He added, "In 2007, it was actually much warmer. We are losing the thick component of the ice cover. And if you lose the thick component of the ice cover, the ice in the summer becomes very vulnerable."
This graph from ThinkProgress illustrates a projected rise in sea level if the world's ice caps continue to melt.
NSIDC research scientist Walt Meier said the record, "By itself it's just a number ... but in the context of what's happened in the last several years and throughout the satellite record, it's an indication that the Arctic sea ice cover is fundamentally changing."
Speaking to the New York Times, Jennifer A. Francis, a Rutgers University scientist said:
“It’s hard even for people like me to believe, to see that climate change is actually doing what our worst fears dictated. It’s starting to give me chills, to tell you the truth.”
Paraphrasing NSIDC research scientist Walt Meier who spoke at LiveScience last year, the Christian Science Monitor points out that while a number of factors contribute to ice melt, greenhouse gases are the likely culprit:
Scientists attribute the shift to a combination of natural forces. For example, a storm in early August coincided with an acceleration of melt that occurred at the same time. However, over time, the effects of winds, clouds and other natural conditions should, in theory, balance themselves out. It is the emission of greenhouse gases that alters the long-term trend by warming the planet.
If all this seems a little abstract, here's a video, based on data compiled by NASA's Nimbus-7 satellite and the U.S. Department of Defense's Defense Meteorological Satellite Program.