Expect more ‘bomb cyclones’, courtesy climate change
A severe winter storm or ‘bomb cyclone’ has seized large parts of the United States and Canada, enveloping them in snow and rain. Several video clips out of affected areas seem straight out of apocalyptic movies. Such events may become more common with global warming not being abated any time soon.
The bomb cyclone is a mid-latitude storm fuelled by the interaction of cold Arctic air and warm air over subtropical regions. The storm named Elliot has taken the lives of more than 30 people and affected around 250 million people across the US and Canada.
Elliot has caused record levels of snowfall, rainfall and winds in many regions, all across the United States, right from the border with Canada up to the border with Mexico, an expanse of more than 3,000 kilometres.
On December 23, Buffalo city in New York State recorded 566.4 millimetres of snowfall, according to the private weather company AccuWeather. This was double the previous record daily snowfall of 320 mm in 1976.
More trouble accompanied the snow. The city also recorded 50.2 mm of rainfall, the highest daily rainfall in Buffalo in 144 years. The previous record was 43.9 mm in 1878.
The storm began as a low-pressure system close to the Rocky Mountains, a major mountain range in North America, around December 21, 2022. It intensified rapidly with a 24-millibars drop in pressure within 24 hours and turned into a bomb cyclone.
The rapid intensification was caused by the interaction of the low-pressure system with the cold air from the Arctic. An undulating polar jet stream across the Arctic region brought the cold air so far south.
The undulation of the polar jet stream — a swift swirling band of winds that encircles the Earth — usually happens during winter months. The formation of a bomb cyclone is rather rare. But it happened in 2019 as well.
The Arctic region warms much faster than the rest of the world. This happens due to a positive feedback climate mechanism called the albedo effect, as ice is reflective and returns a large part of the sun’s rays back to the atmosphere.
This effect is weakening the Polar jet stream, which is undulating much more than before, according to US meteorological agency National Oceanic and Atmospheric Administration (NOAA).
This is creating conditions that are much more favourable for the formation of bomb cyclones and hence frigid and stormy weather all across North America.
As the Earth warms further due to human-emitted greenhouse gases, such events could become much more frequent in the near future — one of the many impacts of climate change.
The conditions are expected to abate from December 26 and normalcy will be restored to the eastern and mid-western United States and southern Canada, according to NOAA.