BROOKLIN: Growing scientific evidence of faster than imagined climate change means the United States needs to begin planning how to repel waves of hungry environmental refugees from Mexico , South America and the Caribbean, according to a Pentagon report.

More intense storms, flooding, and rising seas, along with longer periods of drought in Africa and Asia, are likely to result in the eruption of desperate, all-out wars over food, water and energy supplies, says the study, reported by US business magazine 'Fortune' in January.

The Pentagon provided Fortune the previously unreleased report in what commentators see as an effort to get the US business community to take more seriously the threats posed by climate change.

Climate change has long been associated with slow gradual changes over 50 or 100 years. But increasing evidence has emerged that the climate in a large region could change abruptly.

Material found in ice cores in the Arctic and other regions demonstrates that a region's climate can change dramatically in just a few years, says Raymond Schmitt, a senior scientist at the Woods Hole Oceanographic Institution in the US state of Massachusetts.

Such an abrupt shift occurred 1,300 years ago in the Younger Dryas period, pushing Europe back into Ice Age conditions. Another less dramatic shift was the "Little Ice Age", a time of hard winters, violent storms and droughts between 1300 and 1850.

The cause of these wild climate shifts is a change in the huge Atlantic Ocean current that flows from the tropics north to the Arctic, where it cools, sinks to the bottom and flows south again.

Called the "Atlantic conveyor belt" current, it continually brings warm water, therefore warmer temperatures, to the eastern United States and northern Europe, explaining why Britain, at the same latitude as Labrador on Canada's east coast, is relatively temperate.

If the conveyor current slows, it would bring less warm water to the northern regions making them colder, as happened during the "Little Ice Age".

Global warming is melting the ice of the Arctic regions, putting much more fresh water into the North Atlantic ocean, and might be slowing down the conveyor, said Schmitt in an interview.

"Paradoxically, higher global temperatures could put northern Europe into the deep freeze," he added.

To understand the implications, the Pentagon asked scientists (unidentified in the Fortune article) to probe what might happen should the conveyor begin to falter in 2010.

Their answer: within a decade, temperatures would plunge - an average 3.5C in Europe and 2.8C in eastern North America. Massive droughts would affect key agricultural regions. The average annual rainfall in northern Europe would fall by nearly 30 per cent and its climate would become more like Siberia's.

Violent storms, extensive flooding and drought would likely force 400 million people to migrate from uninhabitable regions, the report concluded.

Reduced agricultural productivity in Europe would have an enormous impact on the world's food security, says Lester Brown of the US-based Earth Policy Institute.

"France's warm climate and good soils allows it to produce more grain than all of Canada," he adds, but under the models developed by the scientists the Pentagon contracted, that could change drastically.

Global grain stocks are currently at an all-time low, Brown told IPS, and a major disruption in climate would be a disaster. "It would destabilize countries and the world economy," he added.-Dawn/The InterPress News Service.