WHEN extreme weather strikes, such as the floods in Pakistan, the null hypothesis is to assume that humans have not played a role, then figure out if they did.
That’s the opposite of what should be done, of the US National Center for Atmospheric Research in Boulder, Colorado. We should assume global warming plays a role in every climate event, then ask whether that role is a significant one. The view is likely to be controversial, but a government-convened meeting last week suggests that it is gaining favour (see “Time to blame climate change for extreme weather”)…
