In case you haven’t noticed, it’s pretty hot in the UK. The Met Office has issued an extreme, amber, infrequent heat warning and we have a level 3 heat health alert, just one level below a national emergency. Extreme heat is often known as a silent killer. Its impact is not as obvious as after storms or floods, but in the UK approximately 2,500 people died due to heat-related illnesses in 2020, a worrying figure as extreme heat becomes more frequent. Earlier this year, the Met Office raised the threshold of what is considered a heat wave in some parts of the UK, and yet these events continue to occur with increasing frequency.
The problem is not isolated in the UK. Continental Europe is experiencing its third major heat wave this year, with temperatures reaching 47ºC in some parts of Spain. Many parts of Europe suffered from an unusually dry spring, which caused widespread drought conditions and increased the chances of forest fires during periods of extreme heat, as Portugal is now experiencing.
The inescapable truth is that heat waves occur more frequently and increasingly hotter, and this is due to man-induced climate change. Here in the UK, 40ºC summers are increasingly likely. Earlier this week, forecast models showed simulations that exceed this marker, suggesting that it is physically possible in the current climate. We are unlikely to reach these temperatures this month, with most forecast models showing highs in the mid-1930s, but scientists at the Met Office have shown that by the end of the century the UK could experience days of 40ºC every three or four years under a high-emission scenario. If emissions are reduced to maintain the Paris climate agreement, the probability is reduced to about 15 years. We are currently on track to reach a point between the two.
Last June, western North America experienced a record heat wave, with Canada setting a new national temperature record of 49.6 ° C, almost 5 ° C warmer than previously observed. . One extreme of this magnitude was unthinkable before it occurred, but a study last year showed that scorching temperatures are to be expected, in a world experiencing undeniable climate change. The work highlighted Europe as one of the regions most at risk from these record heat waves. According to lead author Erich Fischer, as in disciplines such as high jump, where world records are old and only broken by small increments, record heat should become rarer and margins smaller as the longer we measure. But because of climate change we are observing the opposite; the climate currently behaves like an athlete with steroids. Another recent study identified Europe as a heat wave point, with extremes rising three to four times faster than other mid-latitudes. Changes in lightning current that cause more persistent heat waves contribute to this accelerated trend, the research showed.
As temperatures become higher and more dangerous, rapid adaptation will be key to reducing the impacts of heat waves on society. There are many relatively simple measures that can help. The impacts of heat are expanding in cities, and with almost 70% of the world’s population expected to live in cities by 2050, thinking about the extremes of heat within urban planning is essential. Adding more green spaces to cities would help reduce air temperature and create shaded spaces, reducing the need for mechanical cooling. This would not only be beneficial in a heat wave, but it would also make cities more pleasant places to live. The benefits of adding green spaces are endless. They have been shown to reduce air pollution and flood risk, improve mental health and create better social cohesion.
As we look to the turn of the century, there is reason for cautious optimism. While heat waves are expected to become warmer and happen more as emissions continue, more extreme events can be prevented by mitigation. Any reduction in future emissions will help reduce the magnitude of the heat waves we will experience. The sooner the world can achieve zero net emissions of greenhouse gases, the faster these worrying trends will stabilize.
Vikki Thompson is a climate scientist at the University of Bristol