What if tornadoes increased anyway?

Back in 2011, Roy Spencer wrote disparagingly of the suggestion that global warming was likely to increase the number of tornadoes in the US.  Wrong, said Spencer: if anything, global warming suggests fewer tornadoes.

I assumed he might be right on that; but then again, it seems Nature may not have got the message:

The frequency of large-scale tornado outbreaks is increasing in the United States, particularly when it comes to the most extreme events, according to research recently published in Science.

The study by researchers including Joel E. Cohen, a visiting scholar at the University of Chicago, finds the increase in tornado outbreaks does not appear to be the result of a warming climate as earlier models suggested. Instead, their findings tie the growth in frequency to trends in the vertical wind shear found in certain supercells—a change not so far associated with a warmer climate."What's pushing this rise in extreme outbreaks, during which the vast majority of tornado-related fatalities occur, is far from obvious in the present state of climate science," said Cohen, the Abby Rockefeller Mauzé Professor at Rockefeller University and Professor of Earth and Environmental Sciences at Columbia University, who conducted the research while a visiting scholar in UChicago's Department of Statistics.

It reminds me of the not entirely unforeseen, but not as widely expected as it might have been, phenomena of the AGW-primed wandering polar vortex sucking cold air further South in NH winters, while the Arctic has exceptionally warmer Christmases.  In other words, a case of a bit of a topsy-turvy effect of AGW.  Just the potential for the Atlantic currents to slow and make England and Northern Europe colder in winter, too.  (See a few posts back, if you missed it.)

Climate change is perhaps a bit, um, lumpier than some may have expected. 

Or, it may be a case of Spencer being wrong, but for the right reason?  Which makes a break from his general AGW line of being wrong for the wrong reason.