Cape Town, South Africa ? If we don’t deal with climate change decisively, “what we’re talking about then is extended world war,” the eminent economist said.

His audience Saturday, small and elite, had been stranded here by bad weather and were talking climate. They couldn’t do much about the one, but the other was squarely in their hands. And so, Lord Nicholas Stern was telling them, was the potential for mass migrations setting off mass conflict.

“Somehow we have to explain to people just how worrying that is,” the British economic thinker said.

Stern, author of a major British government report detailing the cost of climate change, was one of a select group of two dozen — environment ministers, climate negotiators and experts from 16 nations — scheduled to fly to Antarctica to learn firsthand how global warming might melt its ice into the sea, raising ocean levels worldwide.

Their midnight flight was scrubbed on Friday and Saturday because of high winds on the southernmost continent, 3,000 miles from here. While waiting at their Cape Town hotel for the gusts to ease down south, chief sponsor Erik Solheim, Norway’s environment minister, improvised with group exchanges over coffee and wine about the future of the planet.

“International diplomacy is all about personal relations,” Solheim said. “The more people know each other, the less likely there will be misunderstandings.”

Understandings will be vital in this “year of climate,” as the world’s nations and their negotiators count down toward a U.N. climate conference in Copenhagen in December, target date for concluding a grand new deal to replace the Kyoto Protocol — the 1997 agreement, expiring in 2012, to reduce carbon dioxide and other global-warming emissions by industrial nations.

Solheim drew together key players for the planned brief visit to Norway’s Troll Research Station in East Antarctica.

Melting ice, rising seas, dwindling lakes and war — the stranded ministers had a lot to consider. But many worried, too, that the current global economic crisis will keep governments from transforming carbon-dependent economies just now. For them, Stern offered a vision of working today on energy-efficient economies that would be more “sustainable” in the future.

“The unemployed builders of Europe should be insulating all the houses of Europe,” he said.