The World Bank's climate change unit put out a tweet about climate threats to Eastern Europe yesterday that caught my eye. This one:
#ClimateChange & rising temps increase #health #risks in several ways: http://t.co/k83V1EJCHU #climateaction pic.twitter.com/MOzNKxzGmS
— World Bank Climate (@wbclimatechange) August 23, 2015
There's plenty to take issue with, but let us pick on the claims about chikungunya.
Chikungunya is a viral disease, which is passed to humans by two species of mosquito: A. albopictus and A. aegypti. The problem with claiming that global warming is going to increase the risk of chikungunya is that although A. albopictus is native to East Asia and India, there are established populations in cold countries too: Alaska, North Korea, and Japan are just a few examples. In other words the species is very versatile and can thrive in both cold countries and in warm ones. It's therefore hard to make a case that a bit of warming is going to change things very much.
The story is a little different for A. Aegypti, but it certain seems to have been implicated in historic outbreaks of yellow fever in such tropical hellholes as Boston Massachusetts and Philadelphia, Pennsylvania. Its lifecycle revolves closely around stagnant water and its spread across the world is closely associated with the trade in used tyres. One might therefore argue that the (alleged) drying of the Mediterreanean in a warmer world will actually reduce the prevalence of chikungunya rather than expanding it. In truth nobody really knows.
Oh yes, and when the World Bank tells us that chikungunya will become increasingly prevalent in the Balkans, would it not have been helpful of them to point out that breeding populations of A. albopictus have been observed in the region since the 1970s?
On this claim at least, the World Bank seems guily of sexing things up rather than reflecting the scientific literature.
Is there a climate conference coming up or something?