According to an article in Science magazine titled “Quantifying the Influence of Climate on Human Conflict” global warming may result in “amplified rates of human conflict could represent a large and critical impact of anthropogenic climate change”. The article is gated, so I can’t look at the details buts it’s worth doing a sanity check on the main conclusion.
In the abstract the authors claim:
We find strong causal evidence linking climatic events to human conflict across a range of spatial and temporal scales and across all major regions of the world. The magnitude of climate’s influence is substantial: for each 1 standard deviation (1σ) change in climate toward warmer temperatures or more extreme rainfall, median estimates indicate that the frequency of interpersonal violence rises 4% and the frequency of intergroup conflict rises 14%.
I don’t find this hard to believe. If you’re going to have intergroup conflict then it’s easier in the summer than the winter. The war in Afghanistan has a strong seasonal component to it, usually referred to as the “summer fighting season”, which results in easily modeled oscillations in kinetic activity. See for example IED trends:
The trend is a result of the number coalition troops in Afghanistan and superimposed on that is an oscillation which troops on the ground have no trouble identifying even without the use of graphs or statistics.
So it’s no surprise the authors found a strong correlation between rising temperatures and rising conflicts. But the key here is “if you’re going to have intergroup conflict”. During my lifetime, the global risk of a military aged male dying in a conflict reached an all time low. On a per capita basis, we’ve easily been living in the most peaceful time in man’s history and this seems to be part of a long term trend (the German rate of combat deaths during the world wars are supposedly lower than those seen in primitive tribal societies). See for example this:
and yet you can find endless graphs like this one showing a global rise in temperatures over the same time period:
So if the authors really did find a strong correlation “across a range of spatial and temporal scales” then either these global trends in temperature change are wrong, or the authors of that science study error when they infer “anthropogenic climate change” would have a “large and critical impact” on “human conflict”.