On 17 April 2007, the United Nations Security Council deliberated on the political and security implications of climate change, a geophysical phenomenon far removed from the traditional preoccupations of international security. Sceptics branded the debate an unwarranted diversion from more urgent matters and argued that climate change ought to remain the preserve of environmental agencies. But this view is not shared by an increasing number of influential policymakers and practitioners, who accept that unmitigated climate change will have profound consequences for global security. They include Nobel Prize winner and former U.S. Vice-President Al Gore, French President Nicolas Sarkozy, German Foreign Minister Frank-Walter Steinmeier, Australian Prime Minister Kevin Rudd, and the former and current British Prime Ministers Tony Blair and Gordon Brown. While still in office, Blair observed that “there will be no genuine security if the planet is ravaged by climate change”. His chief climate change adviser, Sir John Houghton, believes that climate change is “a weapon of mass destruction” and, at least, as dangerous as international terrorism, a view shared by Rudd's Federal Police Commissioner Mick Keelty, who sees climate change as “the security issue of the 21st century”. Underlining this shift in sentiment, the European Union's Commissioner for External Affairs, Benita Ferrero-Waldner, declared that global warming has moved to the heart of Europe's foreign policy, while Steinmeier characterized climate change as “a threat to world-wide peace and security”, warning that as the polar ice melts rival territorial claims in the Arctic could turn into a “cold war”.

Hard-headed military and intelligence analysts around the world are also beginning to focus on climate change as a serious strategic issue. In 2002, Andrew Marshall, the long-time head of the U.S. Department of Defense's Office of Net Assessments and arguably the most influential thinker in the Pentagon over the past three decades, commissioned a report by two consultants to explore the security implications of an abrupt climate change event. Although shelved by climate change sceptics in the George W. Bush White House, this path-breaking analysis was followed by a 2007 study reflecting the views of a dozen retired senior U.S. military officers which found that climate change is both a “threat multiplier” and “a serious threat to America's national security”.