Climate change could be responsible for as many as 150,000 deaths around the world every year, according to health experts at the UN climate change conference being held in Montreal.

The biggest culprit is diarrhea caused by contaminated water, but heat waves and insect-borne diseases are also growing problems.

Warmer weather helps microbes and insects to breed faster, setting conditions for the spread of bacterial disease or insect-borne viruses such as West Nile. More extreme weather can also lead to flooding, air pollution and smog.

People with respiratory problems and allergies feel the effects of changing weather patterns, a trend Canadian medical professionals have noticed.

"Climate comes in and exacerbates certain of these situations," said Jacinthe Séguin, who manages climate change policy at Health Canada. "So certainly it adds an extra pressure on the existing services."

Weather-related illnesses are not going away, and health-care providers need to be prepared, said Dr. Pierre Gosselin, a physician who does climate change research for Quebec's public health institute.

"We'll need to change our act," said Gosselin. "We'll need to take into account that chronically ill people in hospitals and other more fragile people will need special care in the future."

Quebec has taken some steps at addressing climate-related problems, such as Montreal's emergency heat wave plan and the city's new anti-idling legislation, but more needs to be done, Gosselin said.

Acting without U.S.

At the conference, some delegates are urging Canada to move ahead on cutting greenhouse emissions and abandon attempts to include the United States.

The U.S. releases one quarter of the world's greenhouse gases. U.S. President George W. Bush's administration pulled out of the Kyoto Protocol four years ago and has refused to commit to any fixed targets to reduce emissions.

"We have to start leading by example," said Marianne Douglas, a professor at the University of Toronto who studies changes in the Arctic environment. "We can't keep dragging our feet. Let's get on with it."

Politicians often find it difficult to go ahead with decisions that have economic consequences without co-ordinating with the U.S., said Bill Hare of Greenpeace International.

"Here is the moment where the international community can be held up by the United States or choose to bypass them," said Hare.

Industrialized and developing nations need to come up with a strong plan of action on climate change that hasn't been watered down to accommodate the U.S. after the Kyoto Protocol expires in seven years, Hare said.