Scientists indicate that severe cold spells will still occur even when winter is generally warmer.
After a record-breaking hot summer, many regions in the United States are now grappling with snowstorms, freezing temperatures, and life-threatening cold winds, CNN reported on January 15. However, this is not a reason to deny the reality of climate change and global warming.
Heavy snowfall on January 12 in Sioux City, Iowa. (Photo: Kevin Dietsch/Getty Images)
2023 was the hottest year on record with an average global temperature of 14.98 degrees Celsius, nearly 1.4 degrees Celsius higher than pre-industrial times. In the long term, the human-induced climate crisis is leading to a concerning trend: snow is gradually disappearing in the Northern Hemisphere. Some scientists even suggest that climate change may contribute to cold spells in the U.S. because warming in the Arctic increases the risk of frigid polar air spilling southward.
Weather is heavily influenced by jet streams – fast-moving air currents high in the atmosphere. When the jet stream shifts southward, it can push Arctic cold air down into North America, Europe, and Asia. Conversely, when the jet stream retreats northward, warmer air can also advance further north. Last January, Europe recorded a record warm winter.
Another factor to consider is the polar vortex – a belt of strong winds at high altitudes in the stratosphere, positioned above the jet stream, surrounding the Arctic. The polar vortex acts like a spinning top. In its normal state, it spins rapidly, “trapping” cold air in the Arctic region. However, it can become disrupted and distorted, allowing cold air to spill out and affect the path of the jet stream. This occurred in 2021, leading to a severe cold spell in Texas that resulted in nearly 250 fatalities and widespread power outages.
The connection to climate change is also present. 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 argue that the connection between Arctic warming and cold spells is not yet clear. There have been many instances of very cold winters in the Northern Hemisphere coinciding with warm winters in the Arctic, but the challenge lies in separating cause from effect, according to James Screen, a climate science professor at the University of Exeter.
Screen noted that severe cold spells may occur solely due to normal climatic fluctuations. In other words, even if winter is warmer, severe cold spells will still arise.
Climate change may also affect the severity of winter storms, as a warmer atmosphere retains more moisture, leading to heavier rainfall or more intense snowfall.
Scientists are still working to clarify the complex relationship between climate change and extreme cold events, but they all agree that the current trend is toward warmer winters. “If we look at the data, we see that in the long term, global warming is causing cold spells to occur less frequently and their severity to diminish,” Screen remarked.
