Note: This was cross-posted to my own blog.
Last week, the New York Times published a nuanced and thoughtful piece on the complicated scientific relationship between climate change and health outcomes. It lays out several health effects that advocates frequently bring up – vector-borne diseases, natural disasters, and temperature extremes – and examines the strength of the research behind each association.
The article’s tone is cautious, and it acknowledges early on that public health initiatives based on climate risk are politically fraught and, in some cases, the science is not as robust as some would like.
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.
“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.
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.”
The central point of the article is that the science examining climate and its effects on health is (as most scientists will cheerfully admit) quite complicated, and the data that the scientific community has on the subject is incomplete and patchy for many countries and geographic regions. The upside to this, however, is that we now have much more data than we used to, in no small part thanks to increased political will and a greater sense of urgency.
Evidence is accumulating, however. In 2000, the first National Climate Assessment, a government document weaving together the best evidence on climate change, had just 21 pages on health. The most recent assessment included a special section on health that filled more than 400 pages.
Two peer-reviewed British journals — Philosophical Transactions B and The Lancet — have dedicated many pages to the topic this year. Europeans, unburdened by the level of political controversy over climate change in the United States, often give more conclusive interpretations of the science.
“We are in a far more certain place now,” said Nick Watts of the University College London Institute for Global Health and a co-author of the Lancet analysis. “We feel very comfortable talking about direct effects of climate change on health.”
One thing that the article pointed out was that the effects of climate health – particularly with regard to temperature extremes – is that they disproportionately affect the poor because they are more vulnerable to the elements. This is one thing that we focused on in the health chapter of Climate Risk and Resilience in China (which I co-authored) and why I like the idea of working to reduce climate-related risks to the most vulnerable populations, as that may be a less politically controversial option. No one can argue that many lives are at risk from a heat wave when so many have no access to AC.
Rose Schneider, the IH Section’s Climate Change Working Group Chair, agreed on that point of the article. “It makes sense to be ‘skeptical’ and it is true that especially in developing countries most is written about ‘projections’ of the effects on health, but it is true that the toll is much worse, especially on the poor, if from nothing else than major climate events like floods, windstorms, crop damage from drought, and sea rise. I liked the last line of the article; I’m not waiting.”
As Dr. Kinney noted, “if we wait for the health evidence to be ironclad, it may well be too late.”