Climate 'future health threat'

Outbreaks of human malaria, butterflies beset with parasites, disease-stricken corals, and trees overgrown with fungus.

That is the gloomy picture of tomorrow's planet painted by scientists in the United States.

After sifting through hundreds of scientific papers, they warn that infectious diseases will rise as the world gets warmer.

One consequence is that entire species of animals could be wiped out.

Human tropical diseases may spread outside their normal geographical range, affecting more and more people.

Endangered wild animals such as lions and eagles could also succumb to infections.

Political plea

The warning comes in a review published in the journal Science.

According to the team of US experts, it is the first broad look at the effect of climate change on various pathogens of crops, plants, wild animals and humans.

Dr Richard Ostfeld of the New York-based Institute of Ecosystem Studies told BBC News Online: "Disease now has to be considered another main player on the climate warming stage.

"We need to be taking climate warming much more seriously than we currently are.

"By 'we' I refer to international agencies but also the US Government."

Plant stress

Driving the predicted rise in infectious diseases are changes in temperature, rainfall, and humidity, which give bugs a boost.

The theory is that pathogens would be able to spread over a wider range, and increase their survival rate.

Climate differences might also "stress" plants and animals, making them more susceptible to infection, say the scientists, led by Professor Drew Harvell of Cornell University.

They are calling for further research into the likely impact of climate change on disease, including:

• Surveys of the amount of disease present in wild animal populations
• Investigating the effects of different climate variables - temperature, moisture, etc - on disease
• Better forecasting of outbreaks of disease linked to climate among crops and people
• Looking at how quickly pathogens can adapt to changes.

"Climate change is a monster of many faces and this study underlines the multiple stresses it puts on people, wildlife and the environment," she told BBC News Online.

"The increasing risk of infectious diseases will put an additional strain on species struggling to adapt to a climate that is changing faster than ever before.

"Our future health, as well as that of our planet, depends on us tackling this global threat now."