Is Weird Winter Weather Related to Climate Change?

This winter’s weather has been weird across much of the Northern Hemisphere.  Record storms in Europe; record drought in California; record heat in parts of the Arctic, including Alaska and parts of Scandinavia; but record freezes too, as polar air blew south over Canada and the U.S., causing near-record ice cover on the Great Lakes, sending the mercury as low as minus 50 degrees Celsius in Minnesota, and bringing sharp chills to Texas.

Everyone is blaming the jet stream, which drives most weather in mid-latitudes.  That would be a significant development.  For what happens to the jet stream in the coming decades looks likely to be the key link between the abstractions of climate change and real weather we all experience.  So, is our recent strange weather a sign of things to come?  Are we, as British opposition leader Ed Milliband put it this month while surveying a flooded nation, "sleepwalking to a climate crisis"? 

The story gets tangled because trying to identify long-term trends amid the noise of daily weather is hard.

Is Weird Winter Weather Related to Climate Change?