DEADLY MIGRATION

Global warming brings heat-loving organisms to chillier regions

The Danish angler never saw his killer. Earlier this summer the 62-year-old (whose name was never released by Danish authorities) was fishing with a friend in the Baltic Sea when a microscopic marine bug entered his system, probably through a cut or scrape. Within a week he was dead, one arm already amputated. His attacker: Vibrio vulnificus, a flesh-eating bacterium that normally makes its home in the warmer waters of the Gulf of Mexico. Although the bug is not always fatal, it can be especially dangerous to the old or the weakened.

Was this a freak accident caused by a rogue organism? Maybe not. Some scientists argue that last summer’s soaring temperatures are part of a warming trend that is encouraging a slew of heat-loving organisms to extend their habitats into the once chillier North. Recent tests in Germany showed that Vibrio vulnificus was present in more than nine out of 10 samples of Baltic Sea water. “Microorganisms aren’t clever,” says Tove Roenne, a doctor with Denmark’s National Board of Health. “They just do whatever the temperature tells them to do.”

Plenty of victims can testify to the consequences. The authorities on the Italian Riviera were forced to close beaches this summer after more than 100 holidaymakers were hospitalised following exposure to Ostreopsis ovata, tropical algae that can cause rashes and diarrhoea. Farm animals, too, have suffered. Cattle herds in Northern Europe this summer came down with the region’s first cases of potentially fatal Blue Tongue disease, a midge-borne ailment previously associated only with the Mediterranean region.

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The link between global warming and the spread of warmth-loving diseases is not ironclad. Blue Tongue disease might have found its way north through a zoo animal. And this isn’t the first time that Vibrio vulnificus has surfaced in the Baltic. Infections were reported during the warm summer of 1994. But scientists are beginning to agree that there is indeed an ominous pattern. “Is climate change really causing new public-health problems at the moment?” asks Paul Hunter, professor of health protection at the University of East Anglia. “The answer to that would almost certainly be yes.”

Even the doomsayers have been surprised by how rapidly disease seems to be spreading northward. For years, Paul Epstein, associate director at the Harvard Medical School Center for Health and the Global Environment, has warned that global warming is responsible for the northward drift of tropical diseases, including malaria, dengue and West Nile Virus, the mosquito-borne blight that has killed more than 700 in North America since its appearance in 1999. “Our models were expecting this to happen,” he says, “but not until much later in the century.” Epstein warns that increasing carbon dioxide levels could be stimulating a dramatic rise in pollen production from ragweed, bad news for allergy sufferers.

Even warm-weather countries are not immune. The charity Christian Aid reported this summer that 180 million people in sub-Saharan Africa could die of diseases — notably malaria — made worse by climate change before the end of the century. Already cases are being reported at ever-higher altitudes in mountain areas once considered too cool for disease-carrying mosquitoes. “The brunt will fall on those living in low-income settings of the South,” says Andy Haines, an authority on the impact of climate on disease at the London School of Hygiene and Tropical Medicine. Still, no one can be sure of escape. “We are only at the beginning of a process that will play out over centuries,” he says, “and we don’t fully understand.” A hotter world won’t be a safer world, for any of us.

—Newsweek / WILLIAM UNDERHILL