Was the Syrian civil war partly caused by climate change? Prince Charles, for one, seems to think so. "There is very good evidence indeed that one of the major reasons for this horror in Syria was a drought that lasted for about five or six years," he told Sky News, adding that climate change is having a "huge impact" on conflict and terrorism.

The Prince is not alone on this one: he joins a chorus of voices making similar claims. In the US President Obama, Al Gore, and the democratic presidential hopefuls Martin O'Malley and Bernie Sanders have all talked of a link between climate change and the Syria conflict, Sanders going so far as to argue that climate change is "directly related to the growth of terrorism".

In the UK, the Syria connection has been drawn in government-commissioned reports and by leading NGOs, as well as by activists and commentators ranging from Charlotte Church to George Monbiot.