guardian | Senior US government officials are to be briefed at the White House this week on the danger of an ice-free Arctic in the summer within two years.
The meeting is bringing together Nasa's acting chief scientist, Gale Allen, the director of the US National Science Foundation, Cora Marett, as well as representatives from the US Department of Homeland Security and the Pentagon.
This is the latest indication that US officials are increasingly concerned about the international and domestic security implications of climate change.
Senior scientists advising the US government at the meeting include 10 Arctic specialists, including marine scientist Prof Carlos Duarte, director of the Oceans Institute at the University of Western Australia.
In early April, Duarte warned that the Arctic summer sea ice was melting at a rate faster than predicted by conventional climate models, and could be ice free as early as 2015 - rather than toward the end of the century, as the UN Intergovernmental Panel on Climate Change (IPCC) projected in 2007. He said:
"The Arctic situation is snowballing: dangerous changes in the Arctic derived from accumulated anthropogenic green house gases lead to more activities conducive to further greenhouse gas emissions. This situation has the momentum of a runaway train."
Duarte is lead author of a paper published last year in Nature Climate Change documenting how "tipping elements" in the Arctic ecosystems leading to "abrupt changes" that would dramatically impact "the global earth system" had "already started up". Duarte and his team concluded: "We are facing the first clear evidence of dangerous climate change."