If global warming is not simply warmer weather, but rather increasingly crazy weather, then this winter has given us ample evidence. An irony of global warming for eastern North America is it seems to be the one place that is getting colder and snowier winters thanks to global warming.
Curse you, Arctic oscillation! New York City just suffered through its coldest February since 1934, and its second-coldest month (any month) since then. Boston’s snow has been of historic proportions. And cities from Toronto and Buffalo to Bangor, Maine, recorded the coldest month in their recorded histories. On the other side of the continent, cities from Salt Lake City, Utah, to San Francisco and Seattle recorded their warmest winter months in history.
In Europe, 2014 was the hottest year on record, based on an analysis that examined temperatures going back to the 16th century, with global warming overwhelmingly the primary factor for such extremes. And, globally, 2014 was the hottest year on record, with the top 10 hottest years all occurring since 1998. There hasn’t been a year with an average global temperature below the 20th century’s average since 1976.
But nonetheless millions of people are suffering through an extraordinarily rough winter for a second consecutive year. And it may be that shrinking ice in the Arctic Ocean is a significant factor behind the extreme winters much of the Northern Hemisphere is experiencing. The Arctic oscillation is a measure of the relative strength of the jet stream, a high-level atmospheric wind that divides polar air from temperate air. When these winds are strong, the jet stream tends not to wander north and south, bottling up frigid air in the Arctic. When those winds slacken, the jet stream develops into a wave pattern, with large movements north and south.
Those high-level winds speed up and slacken based on the differences in barometric pressure between Arctic and mid-latitude regions; a related measure, the North Atlantic oscillation, is the difference between semi-permanent low pressure near Iceland and semi-permanent high pressure near the Azores Islands. When there are significant waves, or north/south amplitudes, unusually hot or cold weather is the result, depending on which side you are on. These patterns can lock into place for weeks or sometimes months, leading to persistent extreme weather.
What is causing these patterns? Research continues, but there is an increasing amount of evidence that a warming Arctic is the culprit. The Arctic is warming faster than the globe as a whole, and the polar ice cap is shrinking as a result, which in turns causes faster warming. Jeff Masters of the Weather Underground, in a discussion of a paper by Rutgers University scientist Jennifer Francis, summarized this theory:
“[T]he extra heat in the Arctic in fall and winter over the past decade had caused the Arctic atmosphere between the surface and 500 [millibars] (about 18,000 feet or 5,600 meters) to expand. As a result, the difference in temperature between the Arctic (60 – 80°N) and the mid-latitudes (30 – 50°N) fell significantly. It is this difference in temperature that drives the powerful jet stream winds that control much of our weather. The speed of fall and winter west-to-east upper-level winds at 500 [millibars] circling the North Pole decreased by 20% over the past decade, compared to the period 1948-2000, in response to the extra warmth in the Arctic.”
So although, overall, global warming means hotter temperatures, it doesn’t mean there will never be another cold day, and sometimes it leads to counter-intuitive results. Also, there should be some perspective here. Difficult as the sustained cold has been, it is the sort of weather than once was more common. It’s less common now precisely because Earth is getting warmer.
It does not help that the corporate media lazily misuses the concept of “neutrality” to present a false controversy, as if there is still a debate as to whether global warming is happening, or if human activity is the cause if it is. The concept of media “neutrality” is easily exploited by denialist “think tanks” (and other lavishly funded corporate fronts) that pump out reports and provide spokespeople.
Denialist groups, well funded by energy companies and other multi-national corporations concerned with their short-term profits rather than the long-term health of the planet, seek to sew doubt among the public. The manufactured split in public opinion can then be leveraged to claim there is a “controversy,” dampening the resolve necessary to tackle a problem that will ultimately threaten the habitability of the planet. Consider that the reservoirs serving South America’s biggest city, São Paulo, are going dry and scientists believe the cause of the drought is Amazon deforestation.
The more you know, the more you realize you don’t know. Ignorance, however, is self-fulfilling — if you think you know everything, there is no need to learn anything. The global-warming denialists are following the playbook of religious fundamentalists who deny the reality of evolution by falsely claiming that a “controversy” exists in the face of overwhelming scientific evidence.
Those who deny evolution do no more than provide a source of amusement. The denial of a planet-wide crisis is something altogether different.