Photo: Health impacts

Climate change will make incidences of smog more intense, such as the smog seen here over Lake Erie. (Credit: NASA via Flickr.)

Climate change will have a strong impact on human health. As climate change brings tropical weather to higher latitudes, tropical diseases like the West Nile virus will follow. Ecosystem disruption will make the outbreak of water-borne diseases more likely.

Air pollution, which in Canada is largely caused by fossil-fuel use, is already a scourge on public health. Climate change will make smog more intense, and will lead to even higher rates of asthma and heart disease. The most devastating casualties will be inhabitants of poor countries, where there is little infrastructure to deal with changing water tables and increased extreme weather. Among the world's least privileged, the potential for climate-induced disaster is enormous.

Deadly heat

Climate change will cause high-latitude regions, like Canada, to warm drastically. With tropical heat comes tropical illnesses, and large increases in heat-related deaths.

Heat can aggravate health problems, particularly for the old, the young and the ill. For example, Montreal currently has approximately 70 annual heat-related deaths, while Toronto has 20. According to the World Health Organization, these figures are expected to climb to 460 and 290 respectively by 2020 due to climate change.

A hotter world is a sicker world

Rising average temperatures will likely extend the ranges of disease-carrying organisms like mosquitoes, rodents and bats. In 1998, drought followed by heavy rains in western North America led to a sharp increase in the population of deer mice, which carry hantavirus.

The West Nile virus has entered the United States and is moving northward as the continent warms.

Disease-causing tropical plants have also begun migrating northward. A tropical fungus invaded Vancouver Island in 2002, killing one and injuring 52.

Global warming may also increase the risk of respiratory diseases because grasses and allergenic pollens grow more profusely in a warmer environment. A 2002 study showed that ragweed—a potent allergen producer—grew up to 61 per cent faster under conditions expected by 2050.

Air pollution

According to the Canadian Medical Association, air pollution prematurely kills about 21,000 Canadians a year. Recent studies show that close to eight per cent of all non-traumatic mortality in Canadian cities is attributable to air pollution.

Dangerous one-two punch

Burning fossil fuels is the main cause of both air pollution and climate change, and health experts have concluded that climate change will actually make air pollution an even greater health threat—unless fossil-fuel emissions are drastically reduced.

Studies also show that warmer temperatures drive up pollen counts, which worsen symptoms of allergy sufferers. Researchers have found that increased levels of carbon dioxide not only cause more weeds to grow but also encourage each individual weed to release more pollen.

Ground-level ozone

Ground-level ozone is the nasty cousin of stratospheric ozone. Whereas stratospheric ozone (the "ozone layer") protects plants and animals from ultraviolet radiation, ground-level ozone is a primary ingredient of smog. Higher temperatures increase ground-level ozone production, thus climate change will intensify urban smog.

Ozone is toxic at low concentrations and deadly at high concentrations. It bursts cell membranes in the lungs, and as cellular fluids build up, breathing becomes more rapid, shallow and painful. The elderly and children are especially vulnerable, and ozone can lead to lifelong damage as lungs stiffen and scar. Ozone also sensitizes the airways to irritants and other allergens. Elevated ozone levels mean more hospital admissions for asthma, respiratory disease and acute respiratory disorders.

Toxic brew

Air pollution from burning fossil fuels produces many other compounds that hurt our health: carbon monoxide, nitrogen oxide, sulphur dioxide, volatile organic compounds and small airborne particulates. They can cause impaired lung function, shortness of breath, wheezing, asthma attacks and premature death.

By reducing our use of coal, oil and natural gas, we can save thousands of lives and lessen the threat to human health of both climate change and air pollution.

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