Via The New York Times: Unraveling the Relationship Between Climate Change and Health. Excerpt:
Is climate change a serious threat to human health?
Simple logic would suggest the answer is yes, a point that the Obama administration is using to build support for the president’s effort to make climate change a centerpiece of his final months in office.
A White House report listed deepening risks. Asthma will worsen, heat-related deaths will rise, and the number and traveling range of insects carrying diseases once confined to the tropics will increase.
But the bullet points convey a certainty that many scientists say does not yet exist. Scientists agree that evidence is growing that warmer weather is having an effect on health, but they say it is only one part of an immensely complex set of forces that are influencing health.
For example, scientists note that global travel and trade, not climate change, brought the first cases of chikungunya, a mosquito-borne tropical disease, to Florida.
Temperatures may be rising, but overall deaths from heat are not, in part because the march of progress has helped people adapt — air conditioning is more ubiquitous, for example, and the treatment of heart disease, a major risk for heat-related mortality, has improved.
The resurgence of forests in the eastern United States and the subsequent increase in the deer population have helped drive a sharp growth in ticks and Lyme disease. But the increase in the prevalence of the illness in the United States has little to do with the climate, federal health experts say.
“There’s a lot of evidence showing that extreme weather can hurt people, but what we don’t know is whether those effects are getting worse,” said Patrick L. Kinney, director of the Columbia University Climate and Health Program, adding that scientists don’t have the long-term data needed to pinpoint how climate change is affecting health.
Still, climate change is a contributing factor. Ragweed now blooms about two to three weeks longer in the north central United States than it did a few decades ago, extending sneezing and watery eyes further into the fall, according to research led by Lewis H. Ziska, a plant scientist at the United States Department of Agriculture.
The Asian tiger mosquito, which came to the southern United States from Japan in the 1980s, likely in a shipment of used tires, has recently spread as far north as Connecticut, an encroachment scientists have connected to rising temperatures, said Dina Fonseca, an entomology professor at Rutgers University.
Mary H. Hayden, a scientist at the National Center for Atmospheric Research in Boulder, Colo., who studies climate and health, said of dengue fever, a tropical disease carried by mosquitoes: “I don’t think we can dismiss the role of climate. But can we say there is a direct causal link? No, we can’t. It’s more complex than that.”