Scientists: Don’t Make “Extreme Cold” Centerpiece Of Global Warming Argument

  • Date: 21/02/14
  • Jason Samenow, The Washington Post

“The link between recent Arctic warming and increased Northern Hemisphere blocking is currently not supported by observations.”

It’s an intriguing theory – that recently has gotten legs: the melting Arctic – spurred by global warming – is causing the weather’s steering flow, the jet stream, to become more extreme. This extreme jet stream – rather than zipping around the world in a straight circle (right below) – is more frequently meandering off course (left below) and getting stuck in place, sending bitter, prolonged blasts of cold southward and conversely, see-sawing strong heat domes northward. It’s a fascinating paradox: global warming as the culprit for bone-chilling cold.


Regular jet steam (right) versus wavy, "extreme" stream (left) (NOAA)

Regular jet steam (right) versus wavy, “extreme” stream (left) (NOAA)

But more and more scientists are expressing  reservations about this hypothesis, first proposed by Rutgers climate scientist Jennifer Francis and collaborators.

“It’s an interesting idea, but alternative observational analyses and simulations with climate models have not confirmed the hypothesis, and we do not view the theoretical arguments underlying it as compelling,” write five preeminent climate scientists (John Wallace, Isaac Held, David Thompson, Kevin Trenberth, and John Walsh) in a recent letter published in Science Magazine.

Elizabeth Barnes, an atmospheric scientists from Colorado State University, after an attempt to dismantle Francis’ theory last summer, published a second challenge in January.

“…the link between recent Arctic warming and increased Northern Hemisphere blocking is currently not supported by observations,” Barnes’ study concludes.

Related: Researcher defends work linking Arctic warming and extreme weather

Despite this pushback, numerous mainstream press outlets have written about the Francis theory uncritically, failing to present countervailing views.

For example, from the BBC:

The main system that helps determine the weather over Northern Europe and North America may be changing, research suggests.

The study shows that the so-called jet stream has increasingly taken a longer, meandering path.

And from NPR:

The wayward jet stream could account for the persistently severe winter weather this year in the U.S. and Britain, as well as California’s long drought.

Even the White House’s science advisor, John Holdren, expressed support for the theory with only subtle qualification.

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