[sanxiyn]

From IPCC report "Climate Change 2013: The Physical Science Basis" chapter 2:

"In summary, there continues to be a lack of evidence and thus low confidence regarding the sign of trend in the magnitude and/or frequency of floods on a global scale." (2.6.2.2)

"In summary, the current assessment concludes that there is not enough evidence at present to suggest more than low confidence in a global-scale observed trend in drought since the middle of the 20th century, owing to geographical inconsistencies in the trends." (2.6.2.3)

It's not as simple as more energy -> more chaotic weather -> more severe floods and droughts. Unlike other parts of global warming, many changes in extereme events are hypothetical and unsettled. (For floods, we are not sure of sign!)