the crucial 59-degree mark. Cruise ship passengers who had eaten local oysters were soon coming down with diarrhoea, cramping and vomiting - the first cases of Vibrio food poisoning in Alaska that anyone could remember. "We were slapped from left field," said Aguiar, who shut down his oyster farm that year along with a few others.

Proliferation

As scientists later determined, the culprit was not just the bacterium, but the warming that allowed it to proliferate.

"This was probably the best example to date of how global climate change is changing the importation of infectious diseases," said Dr Joe McLaughlin, acting chief of epidemiology at the Alaska Division of Public Health, who published a study on the outbreak. The spread of human disease has become one of the most worrisome subplots in the story of global warming.

Incremental temperature changes have begun to redraw the distribution of bacteria, insects and plants, exposing new populations to diseases that they have never seen before. A report from the World Health Organisation estimated that in 2000 about 154,000 deaths around the world could be attributed to disease outbreaks and other conditions sparked by climate change.

The temperature change has been small, about 1.4 degrees Fahrenheit over the last 150 years, but it has been enough to alter disease patterns across the globe.

Researchers have found that poison ivy has grown more potent and lush because of increased carbon dioxide in the atmosphere.

In Africa, mosquitoes have been slowly inching up the slopes around Mount Kenya, bringing malaria to high villages that had never been exposed before. "It's going to get very warm," said Andrew Githeko, a vector biologist who heads the Climate and Human Health Research Unit at the Kenya Medical Research Institute in Kisumu. "That's going to mean a huge difference to malaria."

Githeko, 49, grew up in the central highlands in a tiny village near the town of Karatina, about 5,700 feet above sea level.

His home was different from most of Africa. The air was damp and chilly. On clear days, he could see the glaciers on Mount Kenya, the second-highest peak in Africa at 5,200 metre.

When he was a child, lowland diseases such as malaria were unknown in Karatina. But perhaps 10 years ago, a smattering of cases began to appear.

According to a landmark UN report released in February, global warming has reached a point where even if greenhouse gas emissions could be held stable, the trend would continue for centuries.

Grim picture

The report painted a grim picture of the future - rising sea levels, more intense storms, widespread drought.

The impact of global warming has not been all bad. Researchers recently found that rising temperatures have helped reduce some diseases related to cold weather.

Given the gradual pace of warming, there are also some chances to adapt.

Life in Aguiar's remote inlet has largely returned to the way it was before. This winter has been cold. Come summer, Aguiar will start sending oyster samples to the state. When the temperature hits about 55 degrees, he'll drop his oyster baskets 60 or 100 feet in the water for about 10 days to clear out the bacteria.

It's a solution he can live with in a warming world.