It's that bastard, Rossby. Blame Rossby.
The Arctic is again overheating a lot like last year. Winter is setting in except it's not, not really.
Something is totally off. The Arctic is super-hot, even as a vast area of cold polar air has been displaced over Siberia...“It’s about 20C [36 degrees Fahrenheit] warmer than normal over most of the Arctic Ocean, along with cold anomalies of about the same magnitude over north-central Asia,” Jennifer Francis, an Arctic specialist at Rutgers University, said by email Wednesday.
Up until October, things were relatively normal—at least, as normal as they can be in the era of record-shattering climate change. In mid-October Arctic temperatures suddenly flattened and then rose, instead of continuing downward as winter progressed. What happened?
“The Arctic warmth is the result of a combination of record-low sea-ice extent for this time of year, probably very thin ice, and plenty of warm/moist air from lower latitudes being driven northward by a very wavy jet stream.” Francis has published research suggesting that the jet stream, which travels from west to east across the Northern Hemisphere in the mid-latitudes, is becoming more wavy and elongated as the Arctic warms faster than the equator does.
Those wavy jet stream things, they're called Rossby Waves. They plunge down toward the tropics, carrying freezing temperatures far to the south, and then soar up into the Arctic, carrying warm air to the polar region.
Last winter's Arctic heatwave triggered cyclonic winds that caused the sea ice to thin about 10 cms. or 4 inches. That meant an earlier spring/summer melt, more exposed ocean water, more heat absorption, a warmer Arctic ocean, a delayed winter freeze - you probably get the idea that this has become a vicious circle, what's being called the Arctic's death spiral. And that, kids, is what's called a natural feedback loop - the very thing we're supposed to be slashing greenhouse gas emissions to avoid triggering. Only it's already well underway.