#WeAreTogether: Advance cold snap forecasts could help ease NHS winter Covid crisis
16 November 2020
Hundreds of early deaths in the UK due to extremely cold winter weather could be anticipated weeks in advance by monitoring atmospheric conditions miles above the North Pole, a new study has shown
Researchers at the University of Reading showed for the first time that there are on average 620 additional deaths in the UK linked to cold weather every time there is a weakening of the Polar Vortex – known as a Sudden Stratospheric Warming (SSW).
These events occur roughly once every two years and can cause extremely cold conditions in northern Europe if they affect the jet stream, as was seen during the infamous Beast from the East event that brought snow and temperatures as low as -14°C to the UK in February 2018.
The study, published in Atmospheric Science Letters, showed that additional deaths peaked between three and five weeks after an SSW. Since these atmospheric conditions can be predicted up to 15 days before they occur, the findings highlight the opportunity to use forecasts to take preventative action to save lives and manage demand on health services – particularly with greater pressure on the NHS caused by Covid-19 in the coming months.
Professor Andrew Charlton-Perez, a meteorologist at the University if Reading and lead author of the study, said: “We know that extreme cold snaps pose a deadly threat, particular to older people, families living in poorly insulated homes or those struggling to pay heating bills. Our study has now put a figure on the number of lives that are at stake each time we detect a sudden stratospheric warming over the Arctic.
“The fact we already have the ability to foresee when these events will happen gives us a three-week window to take preventative action that could help save lives. We can take lots of simple, preventative steps to prevent people from dying, for example by following the cold-weather plan published by Public Health England.
“For the general public that might include checking that the heating for older people who live alone is working properly and paid for, and ensuring they have access to medication they need before the cold hits. Hospitals could also use forecasts to anticipate and prepare for upcoming busy periods.
“Preventing and preparing for increased hospitalisations and deaths will be even more important this winter, with Covid-19 already presenting an immense challenge to our health services.”
The Reading team of scientists looked at temperature changes and excess deaths in the UK following 15 SSWs between 1991 and 2018.
Cold weather is known to cause additional deaths, and these are seen every winter in the UK. In the winter of 2018 – the year of the Beast from the East – there were more than 50,000 excess deaths in England and Wales alone.
Cold conditions affect the heart, lungs and circulation, with blood being pulled away from the skin to retain heat, overloading the internal organs and forcing the body to make the blood thicker to compensate. This raises the risk of serious blood clots, while hospitalisations increase for illnesses such as asthma and flu, particularly among the elderly.
The authors acknowledge that the increased deaths could also be linked to other factors in addition to drops in temperature, such as changes to air quality following SSWs.
SSWs occur when the strong Polar Vortex winds circling the North Pole clockwise high in the atmosphere temporarily weaken, or even reverse direction. SSWs affect winter temperatures in the UK by changing the position and strength of the jet stream. Following SSWs, the jet stream is more likely to be closer to the equator, increasing the likelihood of UK weather being dominated by colder, drier air masses.
SSWs are often followed by cold easterly winds and snowy conditions, as was seen in the UK in 2018. In contrast, there are usually warmer, wetter conditions in Southern Europe.
The researchers say further study should be carried out to see if there is a clear increase in deaths in other countries affected by weather conditions resulting from SSWs, such as Canada and countries in northern Europe.
Charlton-Perez, A.J., Huang, W.T.K., Lee, S.H. (2020); ‘Impact of sudden stratospheric warmings on United Kingdom mortality’; Atmospheric Science Letters; https://doi.org/10.1002/asl.1013