An unusually brutal winter storm is set to pummel more than 160 million Americans, as a stretched “polar vortex” sends a devastating blast of Arctic air, bringing heavy snows and freezing rains.<\/p>\n
Winter Storm Fern is forecast to engulf an area well over half the length of the continental United States, stretching from Texas and the Great Plains region to the mid-Atlantic and northeastern states.<\/p>\n
Scientists say the increasing frequency of such disruptions of the polar vortex may be linked to climate change, though the debate is not yet settled, and natural variability also plays a role.<\/p>\n
What is the polar vortex?<\/p>\n
The polar vortex is a large region of cold, low-pressure air that circulates counterclockwise high above the Arctic, in the stratosphere some 10 to 50 kilometres above Earth’s surface.<\/p>\n
In a typical winter, it forms a relatively compact, circular system that helps lock in the coldest air to high northern latitudes.<\/p>\n
“Usually the vortex spins merrily along and has little effect on our weather, but occasionally it moves or stretches southward over North America, bringing with it a jolt of cold,” senior scientist at the Woodwell Climate Research Center Jennifer Francis said.<\/p>\n
What happens when it stretches?<\/p>\n
At times, big atmospheric waves that form closer to the ground can travel upward and knock the polar vortex out of whack.<\/p>\n
Rather than completely breaking down – as happens during dramatic “sudden stratospheric warming” events – the vortex can stretch out into a more oval shape.<\/p>\n
“Think of it like a rubber band being pulled,” Climate Dynamics scientist at MIT Judah Cohen said.<\/p>\n
“That allows the cold air to expand much further south, like we’re seeing this week here in the United States.”<\/p>\n
Meteorologist at the University of Oklahoma Jason Furtado, whose research focuses on long-range forecasting, said these stretching events are not as long-lasting as complete breakdowns, but are significant nonetheless, especially for North America.<\/p>\n
Is it linked to climate change?<\/p>\n
This is where the science becomes more debated.<\/p>\n
There is broad agreement – reflected in assessments by the UN’s climate science body – that the Arctic is warming much faster than the global average, through a process known as Arctic amplification, and human-caused climate change is behind it.<\/p>\n
Mr Cohen argues that this uneven warming helps amplify large atmospheric waves over Eurasia, which in turn makes the polar vortex spill more frequently over North America.<\/p>\n
“Studies suggest these aberrations in the vortex are happening more often in a warming world, which favors more frequent winter extremes,” said Ms Francis.<\/p>\n
Mr Furtado said observations from the past 20 years do show an increase in such events, but he cautioned against drawing strong long-term conclusions tying them directly to human-caused climate change.<\/p>\n
“In my opinion, it’s harder to make that connection going out much further, simply because I think we just don’t have enough data.”<\/p>\n","protected":false},"excerpt":{"rendered":"An unusually brutal winter storm is set to pummel more than 160 million Americans, as a stretched “polar…\n","protected":false},"author":2,"featured_media":259979,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[42,43,40,38,41,39],"class_list":{"0":"post-259978","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-headlines","8":"tag-headlines","9":"tag-news","10":"tag-top-news","11":"tag-top-stories","12":"tag-topnews","13":"tag-topstories"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/259978","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/comments?post=259978"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/259978\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/259979"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=259978"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=259978"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=259978"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}