WASHINGTON - More people will be exposed to floods, droughts, heatwaves and other extreme weather associated with climate change over the next century than previously thought, says a new report in the British medical journal The Lancet.
The report, published online on Monday, analyses the health effects of recent episodes of severe weather that scientists have linked to climate change. It provides estimates of the number of people who are likely to experience the effects of climate change in the coming decades, based on projections of population and demographic changes.
The report estimates that the exposure of people to extreme rainfall will more than quadruple and the exposure of people to drought will triple compared to the 1990s. In the same time span, the exposure of the older people to heatwaves is expected to go up by a factor of 12, said one of the report's authors, professor of climate-system dynamics Peter Cox at the University of Exeter in Britain.
Climate projections typically are expressed as averages over large areas, including vast expanses like oceans, where people do not live. The report calculates the risk to people by overlaying areas of the highest risk for climate events with expected human population increases. It also takes into account ageing populations - for example, heatwaves pose a greater health risk to old people.
Although other major climate change reports have addressed the issue of how it might affect human health, Mr Cox said the new report is the first large-scale effort to quantify the effects that different types of extreme weather would have on people. "We are saying, let's look at climate change from the perspective of what people are going to experience, rather than as averages across the globe... We have to move away from thinking of this as a problem in atmospheric physics. It is a problem for people."
The Lancet first convened scientists on the topic in 2009, and produced a report that declared climate change was "the biggest global health threat of the 21st century".
Monday's report notes that global carbon emission rates have risen above the worst-case scenarios used in 2009, and that in the absence of any major international agreement on cutting those rates, projections of mortality and illness and other effects, like famine, have worsened.
Governments worldwide are preparing for a United Nations summit meeting on climate change in Paris in December to discuss new policies to limit greenhouse gas emissions.
NEW YORK TIMES