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A huge severe winter storm blasted swathes of the US and Canada over the holiday period, with blizzards and extreme cold leaving at least 60 people dead and millions without power.

The storm, estimated to be more than 3000 kilometres wide and dubbed a “bomb cyclone”, swept across North America from 23 December, hitting US states as far south as Texas as well as the Canadian provinces of Quebec and Ontario.

In Buffalo, New York, more than 120 centimetres of snow fell in 72 hours, while temperatures in Montana dropped to -39°C (-38°F). Millions faced huge disruption to their holiday travel plans, with thousands of flights cancelled and major roads blocked by snow and abandoned vehicles.

The storm was caused by Arctic winds known as the polar vortex dipping south over North America. Some scientists suspect that human-caused climate change may be fuelling this instability in polar weather systems.

The Arctic is one of the planet’s fastest-warming regions, reducing the temperature difference between cold Arctic air and warmer air further south. This could be disrupting the polar vortex’s flow, destabilising a high‑altitude air current called the polar jet stream, causing it to push warm air into the Arctic while driving cold Arctic air south.

The extreme weather looks set to continue into the new year. As New Ů��С��Ƶ went to press, large parts of the US were still under weather alerts, with the US National Weather Service (USNWS) warning that the Great Lakes region will be hit by heavy snow, freezing rain and severe thunderstorms from 3 January. It said that snowstorms and gusty winds “will result in snow-covered roads, reduced visibility, and difficult-to-impossible travel” across Nebraska, South Dakota and Minnesota.

Meanwhile, California was hit by heavy rain and snow in the first few days of 2023, causing flash flooding and rock slides. It is the first of several storms forecast to strike the state over the coming days, according to the USNWS.

As North America battles freezing rain and heavy snow, in Europe, the start of the year brought record high temperatures. Belarus, the Czech Republic, Denmark, Latvia, Lithuania, the Netherlands and Poland all recorded their warmest ever January days on 1 January, according to , an independent climatologist who tracks extreme temperatures.

In Poland, temperatures hit 19°C (66°F) in Korbielów and Jodłownik on the first day of the year, far higher than the 1°C (34°F) average temperature for January, while the Czech Republic recorded highs of 19.6°C (67.2°F) in Javorník, compared with an average of 3°C (37°F) for this time of year. In Germany, 982 monthly temperature records were shattered in the first three days of 2023, according to Herrera.

It follows a year of record warmth across Europe in 2022, which saw the UK provisionally log its hottest ever year and Europe experience the highest summer temperatures on record.

The UK’s Met Office has warned that 2023 is likely to be one of Earth’s warmest years on record, with the average global temperature forecast to be between 1.08°C and 1.32°C above pre-industrial levels. In a press release, Nick Dunstone at the Met Office said the forecast was affected by the expected end of a prolonged La Niña climate event, which has had a cooling effect on global average temperatures for the past three years.

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