The United Nations’ weather agency, the World Meteorological Organization (WMO), said Tuesday the record cold felt in the U.S. during February was the result of the same weather phenomena that sent above-average warmth to parts of the arctic.
At a virtual news conference from Geneva WMO, spokeswoman Clare Nullis told reporters that February saw much colder than average temperatures in North America and Russia, but warmer temperatures in parts of the Arctic and other regions.
Nullis cited a report from the U.S. National Oceanic and Atmospheric Administration (NOAA) this week showing the contiguous United States had its coldest February since 1989. She said the U.S. set 62 all-time daily cold minimum temperature records in a span of five days between February 11 and February 16.
But she was quick to note, “A relatively cold February does not negate the long-term warming trend from climate change.”
The WMO explained February’s weather was influenced to a large extent by a recent meteorological phenomenon called a Sudden Stratospheric Warming Event, which occurred about 30 kilometers over the North Pole. This, scientists say, led to a weakening of the polar vortex, the area of low pressure and cold air surrounding the Earth’s poles, with swirling westerly jet stream winds circulating around them.
Those winds are normally strong enough to keep the coldest air in the Arctic during the winter. But the weakening allowed the cold air to spill out into the mid-latitudes, including the U.S., and for the warmer air to enter the Arctic.
Nullis said statistics show the record cold and cold waves seen last month in the United States and parts of Russia are becoming rarer, while heat records are becoming much more frequent, a trend which the WMO expects to continue.