Justin Gillis in The New York Times:
Scientists refer to global warming because it is about, well, the globe. It is also about the long run. It is really not about what happened yesterday in Poughkeepsie. The entire United States, including Alaska, covers less than 2 percent of the surface of the earth. So if the whole country somehow froze solid one January, that would not move the needle on global temperatures much at all. In fact, even this year’s severe winter weather has affected only part of the country. The Arctic blasts were caused by big dips in the jet stream that allowed frigid air to descend from the polar regions into the central and eastern United States. But toward the west, those dips have been counterbalanced by unusual northward swings of the jet stream that sent temperatures soaring. So while New Yorkers have been shivering this winter, California has been setting record or near-record high temperatures. The state is in its third year of a drought so severe that some towns have started to worry about running out of drinking water.
Alaska has been downright balmy for much of the winter. “Record warmth, confused plants: An Alaska January to remember,” The Anchorage Daily News declared. Likewise, large parts of Russia, Canada and Europe have had bizarrely warm temperatures this winter. Though the case is as yet unproven, a handful of scientists think the 50-degree temperatures in London and the frigid weather in Minneapolis might be a consequence of climate change. They contend the massive decline of sea ice in the Arctic has destabilized a weather pattern that normally keeps frigid air bottled up near the pole. That pattern is known as the polar vortex and its boundary is a fast-moving river of air called the jet stream. When the vortex weakens, the jet stream can develop big kinks, creating zones of extreme heat and cold.
More here.
