Christian Science Monitor
Via CSM:
A bitter Arctic blast spanning the central and eastern US has propelled the phrase “polar vortex” from the pages of dense scientific papers to headline status as frigid temperatures and strong winds close schools and businesses and prompt forecasters to warn of “historic and life-threatening” conditions. […]
Paradoxically, the event may be a harbinger of winter outbreaks to come in the northern hemisphere as Earth’s climate warms, some researchers say – a result of shrinking Arctic Ocean summer sea ice and the projected changes in wind and snowfall patterns triggered by the ocean’s warmth and moisture.
It’s been dubbed the warm-Arctic, cold-continent effect – one that doesn’t show up well in seasonal forecast models but does appear in the real world, says Judah Cohen, director of seasonal forecasting at Atmospheric and Environmental Research (AER), a weather-risk management company based in Lexington, Mass. Climate models operating on longer time scales may be missing the effect as well, he adds.
Washington Post:
Via WaPo:
It’s quite cold across much of the United States right now, thanks to the dread “polar vortex.” Bitterly cold. Horrifically cold.
So what does this tell us about global warming? Not very much. Sorry. A single cold snap in the U.S. doesn’t disprove global warming any more than the record heat waves currently hitting Australia prove that it’s happening. But since a lot of people — like Donald Trump — seem confused on this point, it’s worth recapping a few basics:
1) Global warming refers to the whole planet, not just the United States. The term “global warming” typically refers to the rise in the average temperature of Earth’s climate system since the late 19th century, as well as predictions for future warming. A key bit there is “Earth’s average temperature.” It can be very cold in one part of the world and very hot in another at the exact same time. (Sometimes the exact same weather event can do both: The jet stream is currently making some parts of the U.S. unusually hot and some parts unusually cold.)
What we’re interested in is whether the global average is changing over a longer period. That’s impossible to judge from a single point in time in a small area — the continental United States is less than 2 percent of the Earth’s surface.
2) For example: December 2013 was an unusually warm month even though it was colder in the U.S. So let’s take this past December as an example. North America was colder than the average over the past decade. But Europe and Russia were much hotter than average. India was cooler than average. Australia was warmer than average.