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Are global warming and the plague related?

This is not the first time I have talked about the possibility of a link between global climate change and the plague. Russian scientists are now proposing that in the past a warmer climate has allowed the plague to spread more rapidly. Anecdotal evidence supports this theory as previous outbreaks of the plague have seemingly be curtailed by the onset of winter and the death of fleas that spread the disease. It is logical to assume that a warmer climate would therefore cause more severe and longer outbreaks.

From Reuters:

OSLO (Reuters) - Warmer, wetter weather brought on by global warming could increase outbreaks of the plague, which has killed millions down the ages and wiped out one third of Europe's population in the 14th century, academics said.

Migratory birds spreading avian flu from Asia today could also carry the plague bacteria westward from their source in Central Asia, Nils Stenseth, head of a three-day conference on the plague and how it spreads, told Reuters on Monday.

"Wetter, warmer weather conditions mean there are likely to be more of the bacteria around than normal and the chance of it spreading to humans is higher," he said.

The European Union-funded group has just finished analyzing Soviet-era data from Kazakhstan which show a link between warmer weather and outbreaks of the plague.

This analysis was important as it had not previously been clear whether warmer conditions encouraged the bacteria, fleas and rats to grow or killed them off, Stenseth said. Plague bacteria are often carried by fleas on rats.

"But if it becomes too hot it would kill off the fleas and rodents," he said.

- Read the full article -

However, there may be another explanation to these findings. The link could be in fact that the plague outbreaks themselves are indirectly responsible for the changes in climate, not the other way around. During major plague pandemics, large portions of the world population were killed. That caused a significant drop in the demand for food, and huge tracts of farm land lay fallow. This lead to a large-scale reforestation of previously cleared areas, and therefore acted to suck a lot of carbon dioxide out of the atmosphere. This decrease in carbon dioxide would have reduced the greenhouse effect and caused global cooling. Interesting idea to me. For more on this possibility see my previous post on the matter, or refer to the original source paper that I read this from.

Posted by Bryan Woods | Permalink