Greg Laden insists that this week’s frigid temperatures don’t mean global warming isn’t real:
What is happening instead is the cold air mass that usually sits up on the Arctic during the northern Winter has moved, drooped, shifted, gone off center, to engulf part of the temperate region. Here in the Twin Cities, it is about 8 below zero F as I write this. If I go north towards the famous locality of International Falls (famous for its cold temperature readings often mentioned on the national news) it will in fact be colder. If I go even farther north it may still be a bit colder, but at some point it will start to get warm again, as we leave the giant blob of cold air that has engulfed us. In fact, it is relatively warm up on the North Pole right now.
Eric Holthaus goes one step further:
[D]espite the trolling of Donald Trump and other climate change deniers, global warming is probably contributing to the record cold, as counter-intuitive as that may seem. The key factor is a feedback mechanism of climate change known as Arctic amplification. Here’s how to explain the nuts and bolts of it to your under-informed family and friends:
Snow and ice are disappearing from the Arctic region at unprecedented rates, leaving behind relatively warmer open water, which is much less reflective to incoming sunlight than ice. That, among other factors, is causing the northern polar region of our planet to warm at a faster rate than the rest of the northern hemisphere. (And, just to state the obvious, global warming describes a global trend toward warmer temperatures, which doesn’t preclude occasional cold-weather extremes.)
Since the difference in temperature between the Arctic and the mid-latitudes helps drive the jet stream (which, in turn, drives most US weather patterns), if that temperature difference decreases, it stands to reason that the jet stream’s winds will slow down. Why does this matter? Well, atmospheric theory predicts that a slower jet stream will produce wavier and more sluggish weather patterns, in turn leading to more frequent extreme weather. And, turns out, that’s exactly what we’ve been seeing in recent years. Superstorm Sandy’s uncharacteristic left hook into the New Jersey coast in 2012 was one such example of an extremely anomalous jet stream blocking pattern.
Plumer adds a caveat:
This is still a relatively new idea, and there’s a lot of debate on whether there’s actually a link between Arctic warming and extreme weather. Jennifer Francis of Rutgers laid out the theory here. Back in August, a paper in Geophysical Research Letters disputed the link (and Francis responded here). For now, there doesn’t appear to be a consensus on this topic.
The breaking off of a large chunk of the polar vortex and its visit to the northern U.S. is a random event resulting from a serendipitous arrangement of weather systems. In short, the clockwise flow around giant areas of high pressure over Alaska and west of Greenland have forced the atmosphere’s steering currents to shove the vortex into the northern US. It happened before humans dumped billions of tons of carbon dioxide into the atmosphere and will happen again.
This polar vortex excursion is a single weather event directly affecting about 2 percent of the world. Climate change is measured by evaluating continental to global trends in weather over decades – not events happening over a few days in a little region. For this reason, a fleeting cold wave (or snowstorm) over part of a continent should never be used as evidence for or against climate change.
But it should be used for German DJ YouTube fodder:
The Dish 