By Juliet Eilperin
Washington Post Staff Writer
Thursday, November 17, 2005
Earth's warming climate is estimated to contribute to more than 150,000 deaths and 5 million illnesses each year, according to the World Health Organization, a toll that could double by 2030.
The data, being published today in the journal Nature, indicate that climate change is driving up rates of malaria, malnutrition and diarrhea throughout the world.
Health and climate scientists at the University of Wisconsin at Madison, who conducted one of the most comprehensive efforts yet to measure the impact of global warming on health, said the WHO data also show that rising temperatures disproportionately affect poor countries that have done little to create the problem. They reached their conclusions after entering data on climate-sensitive diseases into mapping software.
"Those most vulnerable to climate change are not the ones responsible for causing it," said the study's lead author, Jonathan Patz, a professor at the university's Gaylord Nelson Institute for Environmental Studies and its department of population health sciences. "Our energy-consumptive lifestyles are having lethal impacts on other people around the world, especially the poor."
The regions most at risk from climate change include the Asian and South American Pacific coasts, as well as the Indian Ocean coast and sub-Saharan Africa. Patz said that was because climate-sensitive diseases are more prevalent there and because those regions are most vulnerable to abrupt shifts in climate. Large cities are also likely to experience more severe health problems because they produce what scientists refer to as the urban "heat island" effect.
Just this week, WHO officials reported that warmer temperatures and heavy rain in South Asia have led to the worst outbreak of dengue fever there in years. The mosquito-borne illness, which is now beginning to subside, has infected 120,000 South Asians this year and killed at least 1,000, WHO said.
Senior U.S. and international officials said they now regard climate change as a major public health threat. In an interview this week, Howard Frumkin, who directs the National Center for Environmental Health at the Centers for Disease Control and Prevention, called it "a significant global health challenge."
Diarmid Campbell-Lendrum, a scientist at WHO's Department of Protection of the Human Environment, said its initial estimates of global warming-related deaths are conservative in light of Europe's massive 2003 heat wave and new research linking climate change to more intensive hurricane activity.
"Climate change makes it even more important to combat diseases of the poor, many of which are highly climate-sensitive," said Campbell-Lendrum, who wrote the Nature paper with Patz. "We already have good evidence that there are a series of significant risks to health, which makes it even more important to curb greenhouse gas emissions in a short period of time."
Some experts, however, questioned whether it was fair to attribute death and illness in the developing world to global warming.
"Wealth is the number one factor in determining vulnerability or adaptability of a country to any of the threats out there," said John R. Christy, a climatologist who directs the Earth System Science Center at the University of Alabama in Huntsville. Christy, who lived in Kenya in the mid-1970s, added, "Thugocracies and other non-democratically accountable governments . . . have no real incentive to create a healthy populace with free markets and therefore free people."
Climate change can contribute to such diseases as diarrhea, malaria and infectious illnesses in a number of ways. In warmer temperatures the parasite that spreads malaria via mosquitoes develops more quickly, for example, and a 2000 study conducted in Peru found that when the periodic El Nio phenomenon boosted temperatures there, hospital admissions of children with diarrhea increased exponentially.
Researchers have also documented an association between rising temperatures and deaths stemming from air pollution, since warmer, sunnier days trigger atmospheric reactions that worsen harmful smog.
Patrick L. Kinney, a professor at Columbia University's Mailman School of Public Health, was the co-author of a study last year in the journal Environmental Health Perspectives that predicted global warming alone could prompt the rise of smog-related deaths in the New York City region by 4.5 percent by the middle of this century, compared with the 1990s.
The study of the health impacts of climate change, Kinney said, "is at a very early research field, but I sense it's beginning to grow rapidly."
Much remains uncertain about the impact of climate change: Harvard Medical School's Center for Health and the Global Environment issued a report this month outlining two possible scenarios with varying degrees of extreme weather events. In one, warming would simply strain the world's resources; the second "would involve blows to the world economy sufficiently severe to cripple the resilience that enables affluent countries to respond to catastrophes."
The center's associate director, Paul Epstein, who helped write the study, said the ecosystems that are now undergoing climate change will shape our future health because they are "our life support systems. They're our food, our air and our water."
Researcher Madonna Lebling contributed to this report.