Less than a decade ago, these questions would have been dismissed outright."Many scientists at the time said that you can never blame an individual weather event on climate change," says Myles Allen of the University of Oxford. But a small meeting of scientists in Colorado last week - organised by the US National Oceanic and Atmospheric Administration, the UK Foreign and Commonwealth Office and the UK Met Office's Hadley Centre, among others - suggests the tide is turning.
The aim of the Attribution of Climate-Related Events workshop was to discuss what information is needed to determine the extent to which human-induced climate change can be blamed for extreme weather events - possibly even straight after they have happened.
Assigning blame in this way is not without precedent. In 2004, Allen and his colleagues showed to a high level of confidence that human greenhouse gas emissions had at least doubled the risk of the European heatwave of 2003 occurring.