27 February, 2018
Scientists say "extreme" warm air high over the Arctic Ocean this week is melting sea ice and sending very cold air to Europe.
And they say such strange weather may become more common as temperatures continue to rise worldwide.
The effects of the warming are clear on Greenland's north coast, where scientists have recorded 61 hours of temperatures above 0 degrees [Celsius] in 2018. That is a record for a place normally frozen at this time of year.
And across the Arctic region, temperatures are now 20 degrees Celsius above the average.
But far to the south, a rare snow storm struck Rome, Italy, on Monday.
"Warm Arctic, cold continent"
Scientists have suspected for more than 40 years that disappearing sea ice in the Arctic Ocean could make areas to the south colder. Climate scientists even use the phrase "warm Arctic, cold continent."
Ruth Mottram is a climate scientist at the Danish Meteorological Institute. "It's never been this extreme," she said.
Lars Kaleschke is a professor at the University of Hamburg in Germany. He told Reuters that it is unclear how often these warming periods will take place.
"The question is whether this weather will happen more often. This is just one event so it's hard to make a causal relationship," he said.
Over time, as sea ice melts, more ocean is being exposed. This releases more heat into the atmosphere. The warmer air may, in turn, change the flow of air currents high in the atmosphere called the jet stream.
Nalan Koc is research director at the Norwegian Polar Institute. He said that the jet stream becomes "wavier, meaning that colder air can penetrate further south and warmer air further north."
The World Meteorological Organization, the U.N. weather agency, says the cold weather in Europe is being caused by a "sudden stratospheric warming" above the North Pole. This has forced colder air south.
Arctic ice disappearing
Ice in the Arctic Ocean is at its lowest recorded levels for late February.
The U.S. National Snow and Ice Data Center says about 14 million square kilometers of the ocean is currently covered with ice.
That is about one million square kilometers less than the long-term average. Scientists have used satellites to observe Arctic ice for more than 30 years.
The head of the United Nations Environment Programme, Erik Solheim, says the weather shows that the earth's climate is warming.
"What we once considered to be anomalies are becoming the new normal," he told Reuters.
Scientists want to know if the Arctic weather is being driven by human activities or natural forces. Satellite temperature measurements only date back to the late 1970s.
The warming temperatures are already causing problems. On the Norwegian island group of Svalbard, temperatures are more than 13 degrees Celsius higher than the long-term average.
Svalbard is home to the Svalbard Global Seed Vault, a center aimed at saving plant genetic material for future generations. The seed vault is located there partly because of Svalbard's low temperatures. But unusually warm temperatures could threaten the collection.
Mottram, of the Danish Meteorological Institute, said Europe's winters have actually become less severe, although this year's temperatures appear low.
"It's not actually that cold. It's just our perceptions have shifted from a normal winter," she said.
I'm Mario Ritter.
Mario Ritter adapted it for VOA Learning English from a Reuters report and other sources. Ashley Thompson was the editor.
We want to hear from you. Write to us in the Comments section, and visit 51VOA.COM.
Words in This Story
causal –adj. having to do with a cause
jet stream –n. a strong current of fast wind traveling above the earth in one direction
penetrate –v. to go through or into something or someplace
stratospheric - adj. relating to the upper layer of the Earth's atmosphere
anomaly –n. something that is not expected or unusual
perceptions –n. the way a person thinks about a something or someone