Scientists say cold spells will still occur even if the winter is generally warm.
People clear snow after a snowstorm on January 9 in Iowa, USA. Photo: Cody Scanlan/The Register/USA Today Network
After a record-breaking summer, parts of the United States are struggling with snowstorms, ice and life-threatening wind chills, CNN reported on January 15. However, this is no reason to deny climate change and global warming.
2023 is set to be the hottest year on record, with the global average temperature reaching 14.98 degrees Celsius, nearly 1.4 degrees Celsius above pre-industrial levels. In the long term, the man-made climate crisis is leading to an alarming trend of disappearing snow in the Northern Hemisphere. Some scientists even argue that climate change could be contributing to the cold snaps in the US, as warming in the Arctic increases the risk of frigid polar air moving south.
Weather is heavily influenced by the jet stream – fast-moving air currents high in the atmosphere. When the jet stream moves south, it can push cold Arctic air down into North America, Europe and Asia. When the jet stream retreats north, warmer air also moves further north. Last January, Europe had its warmest winter on record.
Another factor to consider is the polar vortex — a belt of strong winds that sits high in the stratosphere — above the jet stream — around the North Pole. The polar vortex is like a spinning top. In its normal state, it spins very quickly, trapping cold air over the Arctic. But it can become disrupted and deviate, becoming distorted, spilling cold air out and affecting the path of the jet stream. This happened in 2021, causing a cold snap in Texas that killed nearly 250 people and knocked out power to much of the state.
There are also links to climate change. Some scientists believe that polar vortex disruptions and changes in the jet stream are driven by warming in the Arctic, which is warming about four times faster than the rest of the planet.
However, other scientists say the link between Arctic warming and cold snaps is unclear. There have been times when very cold winters in the Northern Hemisphere have coincided with warm winters in the Arctic, but the difficulty is separating cause from effect, said James Screen, professor of climate science at the University of Exeter.
Screen said that the cold spells could simply be due to normal climate variability. In other words, even if winters were warmer, cold spells would still occur.
Climate change could also affect the severity of winter storms, as a warmer atmosphere holds more moisture, leading to more intense rain or snow.
Scientists are still trying to unravel the complex links between climate change and extreme cold, but they all agree that the trend is toward warmer winters. “If we look at the data, we see that over the long term, global warming is leading to fewer and less severe cold spells,” Screen said.
Thu Thao (According to CNN )
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