The United Kingdom may reach 40 degrees Celsius during the day next week, but nighttime temperatures may also set records. A study illustrates the frequency of ‘tropical nights’ in the United Kingdom over the past several decades and explains why they are likely to cause issues in the nation’s largest cities.
In some locations early the following week, temperatures of 25C (77F) are predicted.
It is a temperature more commonly associated with the middle of a sunny summer day.
In terms of health, however, nighttime temperatures can be just as significant as daytime temperatures that break records.
People have little opportunity to recover if temperatures remain high overnight, putting the body under prolonged stress. Next week’s sweltering nights could lead to an increase in heat-related health problems, at a time when the NHS is already experiencing unprecedented summer strain.
The high overnight temperatures predicted for the upcoming week will increase the number of “tropical nights” in the United Kingdom, where the temperature remains above 20 degrees Celsius (68F).
Our analysis of Met Office data indicates that the UK experienced four tropical nights for the first time in a single year during the summer of 1975.
In August of that year, more than 550 square miles of the country experienced multiple nights of extreme heat for the first time.
Twenty years later, the United Kingdom had one of the warmest summers on record. Manchester, Cheshire East, Copeland, and Barrow-in-Furness were among the hardest-hit regions in the North West.
An estimated 619 additional deaths occurred in England and Wales between July and August. In addition, the mortality rate in Greater London rose by 16.1% during the heatwave.
As 2004 followed a year in which more than 20,000 people perished in Europe due to excessive heat, it is largely forgotten.
Overnight temperatures on August 9, that year, remained above 20 degrees Celsius in 63 regions of the UK. The heatwave affected nearly all of the East Midlands, East Yorkshire, and Norfolk.
On 27 nights over the past decade, high temperatures were observed. This is three times the number from the 1960s.
Is this a fashion? According to the Met Office, tropical evenings in the United Kingdom are too rare to be certain.
Why do high temperatures result in mortality?
The heat does not affect everyone in the same way.
Similar to COVID-19, certain populations are more susceptible than others.
Dr. Sandy Robertson, an emergency care physician and chair of the Royal College of Emergency Medicine’s environmental group, told that cardiovascular problems are more prevalent during heatwaves.
“Your body can cool down by sweating, which dehydrates your body and causes your blood to become thicker. This causes a variety of heart problems and increases the risk of stroke “said Dr. Robertson.
The heat also exacerbates respiratory issues, which may be exacerbated by the fact that air pollution tends to increase with warmer weather.
Consequently, those with underlying health conditions, who are also typically older, are most at risk during hot weather.
The excess deaths attributable to three heatwaves in 2020, which resulted in over 2,500 deaths, indicate that those over 65 were disproportionately affected.
However, age is not the only determinant of vulnerability.
Some studies suggest older women are at higher risk. In 2003, a heatwave in northern France claimed the lives of 15,000 people, of which 65 percent were women.
Those with mental health issues are marginally more susceptible to heat-related issues.
Dr. Robertson stated that there is some evidence that suicidal ideation increases with heat: “Research on Mexico and the United States has shown that if we continue on the current path of climate change, there will be between 9,000 and 40,000 additional suicide deaths in those countries by 2050.”
Those who live alone and in poorly ventilated housing, as well as those who reside in large cities, are believed to be at a greater risk.
The map below depicts regions in England and Wales where heat-related mortality rates have been the highest since 2000. The darker areas surrounding London, Birmingham, and Manchester indicate that residents of these cities are among the most affected.
Some of the geographical patterns remain unexplained precisely.
Likely contributing factors include the quality of housing, people’s access to information about what to do during heatwaves, and other socioeconomic factors.
Professor Antonio Gasparrini, a biostatistician at the London School of Hygiene and Tropical Medicine, stated, “We know a number of the correlations associated with increased deaths due to heat, but not always the exact causal mechanisms through which these things have an effect.”
Urban heat island effects are likely an additional factor that explains city-countryside disparities. This occurs when urban roads and structures absorb and emit heat, making metropolitan areas hotter.
Dr. Eunice Lo, a climate scientist at the University of Bristol, predicts that this will worsen, particularly at night, as the planet’s climate continues to increase.
“We anticipate a nighttime intensification of the urban heat island effect. Important are warm nighttime temperatures because this is when we should recover from the day’s heating load “She stated,
Given the correlation between extremely high temperatures and death, the likelihood of more frequent heatwaves and warm nights is particularly concerning.
The graph below illustrates how the risk ratio – the probability of dying from any cause – climbs drastically with tiny changes in temperature at the chart’s hottest end.
“The rate of increase in mortality risk is significantly greater in really hot temperatures compared to, say, relatively warm temps,” Dr. Lo explained.
However, it is not inevitable that rising temperatures would cause tens of thousands of deaths. Studies indicate that in countries warmer than the United Kingdom, heat-related mortality occurs less frequently at comparable temperatures.
It shows that adaptation, both in terms of people’s behavior and the construction of infrastructure better prepared to withstand hotter weather, can save lives.
