Speaking to business leaders and politicians in the Scottish city of Glasgow, he said that while terrorism alone could never destroy a nation, climate change had the capacity to change the way of life of the entire global population.
"The most profound security threat we face today is global warming," he said. "There may be other terrorist acts, and some of those acts may involve small-scale biological chemical or nuclear attacks."
"There has never been a nation destroyed by terrorism alone and it's not about to start now.
"But I think this climate change has the capacity to change the way all of us live on earth."
Clinton, who served as U.S. president from 1993 to 2001, said recent scientific studies in Antarctica showed the world was warming more rapidly now than at any time in the past 200,000 years.
In a stark warning of the immediacy and severity of the threat posed by rising global temperatures, he said: "If the world warms for 50 years at the rate of the last 10, we will lose our coastal cities in the United States and 50ft of Manhattan will be gone."
Perhaps tacitly attempting to allay the concerns of the United States and other developed nations that efforts to tackle climate change will undermine economic growth, he noted the profits to be made in the emerging clean energy market.
"There is a lot of money to be made there. If I was a 25-year-old and I was starting my life over again I would go into clean energy. I would be a billionaire before you could turn around."
Clinton also urged greater international cooperation, both on a governmental and societal level, on global poverty and the AIDS epidemic in Africa, two issues on which he is now an active campaigner.
The interdependent nature of the world meant that deprivation and disease in even remote regions would impact the security of all nations, he stressed, urging a sense of shared global responsibility.
"We live in an inter-dependent world and that can be good and bad or both," he said.
"We have to try to move towards integrated communities with shared responsibilities and values. We have to do it with greater cooperation.
"And we cannot let the government do it all because the government cannot do it all."
Reaching out to those in need around the world was a form of soft power just as effective and less costly than military force when it came to enhancing global security, he suggested.
Displaying a level of political subtlety that many U.S. analysts lament is now missing from the White House, Clinton detailed an approach that balanced military might with an active focus on winning hearts and minds, not only in conflict situations but the world over.
He cited increased approval ratings for the United States in the Muslim nation of Indonesia after Americans gave millions of dollars in aid following the 2004 tsunami.
Contrasting the relief operation with the bloody conflict in Iraq, he said: "The American military dropped food instead of bombs. We were related to one another as human beings."
"We do need a national defense and a military," he acknowledged, but added: "It's far less expensive to make more partners and fewer enemies."
Back on the home turf of his old friend Tony Blair, Clinton also sprang to the defense of the beleaguered British prime minister.
Britain was "way" better off thanks to Blair's leadership, he said.
The prime minister is currently facing a torrent of calls for him to step down or at least name his departure date, following a series of government crises and disastrous results in last week's local elections.
Scandals involving the accidental release of foreign criminals and Deputy Prime Minister John Prescott's affair with his diary secretary have hit the government hard in recent weeks, and its troubles are far from over. Blair still faces a criminal investigation into claims he nominated wealthy businessmen for seats in Parliament's unelected chamber in exchange for secret loans to the Labor Party, while the National Health Service is becoming increasingly mired in deficit and proposed educational reforms are provoking damaging internal rows.
Following a humiliating outcome in the local elections, which saw Labor relegated to third place in the popular vote behind a resurgent Conservative Party and the Liberal Democrats, some Labor parliamentarians are predicting an internal coup if a change of leadership is not forthcoming.
But Clinton said: "Whatever political problems the government is in, the U.K. is way better off than it would have been had it not been governed the way it has for the last 10 years."
Admitting he had been close to Blair, he said: "I will put a little plug in for the home team."
But the Democrat did not go so far as to place Blair among his most inspirational political figures, who he listed as the former South African President Nelson Mandela, the late King Hussein of Jordan and assassinated Israeli Prime Minister Yitzhak Rabin.
As Clinton departed he added a few more words of encouragement for the embattled British leader, with perhaps just a hint of nostalgia for the days in which left-of-center parties governed on both sides of the pond.
"He has just got to keep working for the people," he told press. "The U.K. looks good from across the Atlantic."
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