The National Climatic Data Center has released its summary of global climate conditions so far this year and finds that the month of May, as well as the period from January through May, were the warmest since thorough record keeping began in 1880.

Here’s the way he summarizes the warming-downpour connection:

We cannot say that any of this year’s flooding disasters were definitely due to global warming, and part of the reason for this year’s numerous U.S. flooding disasters is simply bad luck. However, higher temperatures do cause an increased chance of heavy precipitation events, and it is likely that the flooding in some of this year’s U.S. flooding disasters were significantly enhanced by the presence of more water vapor in the air due to global warming. We can expect a large increase in flooding disasters in the U.S. and worldwide if the climate continues to warm as expected.