Is climate change really to blame?
Uncertainty extends to the health impacts of climate change
As with weather events, it is very hard to pin changing disease patterns unambiguously on
However, experts certainly see a warming climate as a factor in the spread of a range of diseases, from to cholera to yellow fever.
There is concern that the 2014 outbreak of Ebola in West Africa could also be exacerbated by climate change. In this case the relationship is a little more complex because it is related to precipitation. Climate change and precipitation are not directly related, but there is a connection between climate change and precipitation extremes. A 2002 study found a correlation between unexpected shifts from dry to wet weather conditions and outbreaks of Ebola.
But in relation to disease, climate change does not act independently of other factors – changing land use, environmental degradation, mass migration, urbanisation and human behaviours all affect the spread of infection. (Indeed, the role of deforestation in bringing together humans and wild animals infected with Ebola is also under investigation.)
Predicting what might happen to malaria (see our ‘Mosquito measures’ article) is a case in point – and a lack of reliable data makes it hard even to assess what is happening now.
In fact, trying to nail down cause and effect with absolute certainty may be a forlorn hope – and possibly counterproductive. By the time a cast-iron case is made, the damage may already have been done. Some authorities now argue that ‘on the balance of probabilities’ is a good enough basis for action when the stakes are so high.
As the scientist Michael Osterholm put it: “We are struggling to prove [cause and effect] with scientific data, and we can’t. We don’t need West Nile virus to know we are in deep doo-doo… If we are trying to solve it on individual studies, we will be in the court of science for a long, long time, and then it will be too late.”Lead image: