From Our 2009 Archives

Report: Climate Change Threatens Health

Scientists Say Global Warming Will Increase Malaria and Other Diseases

By Salynn Boyles
WebMD Health News

Reviewed By Louise Chang, MD

May 13, 2009 -- A newly released report identifies climate change as the biggest global health threat of the 21st century.

If nothing is done, global warming could affect the health of billions of people throughout the world, with the poor suffering most, according to the report from the University College London and The Lancet.

Deaths from heat waves, malaria, and other vector-borne diseases (diseases transmitted by sources such as mosquitoes or ticks) are projected to rise as global temperatures increase. But the report identifies food and water shortages and increasingly violent weather events as the biggest climate-change-related threats to human health.

Pediatrician Anthony Costello, MD, who chaired the commission that issued the report, says there is new evidence that climate change is occurring faster than many experts had anticipated.

He tells WebMD that recent findings on greenhouse gas emissions, global temperature changes, sea level rise, ocean acidification, and extreme climatic events suggest that climate forecasts made in 2007 by an international panel evaluating climate change may be optimistic.

"The forecasts made by the world climate scientists a few years ago are starting to look too conservative," he says.

Climate Change and Health

Costello points out that since records began to be kept a century and a half ago, 12 of the warmest years on record have occurred within the last 13 years.

He adds that the health effects of climate change are already being seen and will increasingly be felt as temperatures rise.

According to the report:

  • Rising temperatures will affect the spread and transmission rates of vector-borne and rodent-borne diseases like malaria, dengue fever, Lyme disease, hantavirus, tick-borne encephalitis, and a host of other diseases. According to one model, there will be as many as 320 million additional cases of malaria in 2080. And 6 billion people will be at risk for dengue fever, compared to 3.5 billion today.
  • As ocean temperatures rise and more intense seasonal weather events occur as a result, cholera outbreaks may increase.
  • Climate change is projected to make existing food shortages worse. According to one study, half of the world's population could face severe food shortages by the end of the century due to rising temperatures. And hunger, illness, and death due to malnutrition will worsen in Africa and other underdeveloped regions that are already hardest hit by food shortages.
  • Diarrhea and other diseases spread by lack of access to clean water are expected to increase. Average annual rainfall is forecast to decrease in some regions and increase in others, meaning that droughts and floods are likely to become more frequent and intense.
  • Hurricanes, heat waves, flash floods, and other natural events are expected to increase in number and intensity as global temperatures rise. And rapid urbanization leading to inadequate housing, particularly in developing nations, will expose more people to the effects of these extreme weather events.

Costello says the health community is only now beginning to understand the widespread implications of global temperature change on human health.

"We definitely need more research into this," he says. "Health professionals have come late to the climate change debate."

He points out that the poorest 1 billion people on the planet use just 3% of its resources, but these are the people whose health will suffer most from climate change.

The report calls for the formation of an international coalition to study the health implications of global climate change.

"We've got about five years to get this sorted out," Costello says. "It is going to be very difficult and there will be huge political pressure not to do it. But if we don't make changes it could be catastrophic."

SOURCES: The Lancet, May 16, 2009; vol 373: pp 1693-1733. Anthony Costello, chairman, University College London commission; director, University College London Institute for Global Health.

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