New Controversy on Malaria and Climate Change

For discussion of the 2011 paper in PLoS ONE see this new blog post.



Some of my coauthors on our work on malaria and climate change have an article (with others) in the latest issue of Nature. Their main point is that even if climate change has had an effect on the prevalence of malaria in the last century, that effect is swamped by everything else that has been going on. Also that the current distribution of malaria endemicity is no guide to future trends. Both these points seem pretty sensible to me but Joe Romm is outraged. He describes the authors of the paper as "sloppy" because he thinks they exaggerate the degree to which the IPCC support the "Malaria is increasing due to climate change hypothesis". This is a rather indirect criticism. He thinks the IPCC underplayed the threat and accuses them of saying the IPCC overplayed the threat. That's the best he's got against their paper... It's typical of Romm to trash a paper for extraneous reasons if it doesn't fit the global warming is always bad everywhere party line.

In passing, he notes the recent Chaves and Koenraadt paper which he quotes Science Daily as saying debunks our 2002 paper in Nature. I hadn't read it up till now, though citation tracking meant that I was aware of it. I need to do some background research before I can comment in detail on the paper. In the meantime, here is their monthly data for Kericho, Kenya:



Note that this isn't for 1966-2002 in fact despite the article claiming that that is the data they analysed. And here is the data we actually used for 1966 to 1995:



The series are not identical. In both cases the variance seems to go down a little and there does seem to be some possible increase in mean annual temperature. The question is whether it is truly statistically significant. Our answer was no, Chaves and Koenraadt suggest yes. If so, it is a very small change. People are still arguing about whether there is a significant trend in global mean temperature, where there is a much clearer trend...