The Relationship Between Heatwaves and Climate Change

Certain parts of the world seem to be experiencing a lot of heatwaves recently, and even cooler regions are getting heatwaves from time to time in the summer months. We look at the relationship between heatwaves and climate change, how temperatures might continue to reach unbearable heights, and why we need to prepare for this.

What is a heatwave?

A heatwave is defined by the Met Office as “an extended period of hot weather relative to the expected conditions of the area at that time of year, which may be accompanied by high humidity”.

They occur when a slow-moving high pressure system settles over a particular region, causing dry, settled and very warm weather for days or even weeks.

Are heatwaves occurring more frequently?

Evidence collected by scientists in recent years suggests that heatwaves are occurring more frequently as the planet experiences global heating.

In the US, heat waves are occurring three times more often than they did in the 1960s – about six per year compared to two per year.

According to a recent study in Nature, a measure of cumulative heat shows significant increases in almost all regions since the 1950s, mainly driven by heatwave days. At least one extra heatwave day has occurred each decade over the majority of regions between 1950 and 2017.

In the UK, the hottest day of the year for the most recent decade (2008-2017) has increased by 0.8°C above the 1961-1990 average.

What is the relationship between heatwaves and climate change?

Scientists are in agreement that the increase in heatwave frequency can be directly linked to human-caused climate change. As the planet heats up, the conditions for extreme heat become more likely.

A study by the Met Office found that a heatwave similar to the one the UK experienced in 2018 is 30 times more likely to occur now compared to before the industrial revolution because of the higher concentration of carbon dioxide in the atmosphere.

According to scientific information collated by SciLine, record-breaking hot months are occurring five times more often than would be expected without global warming, suggesting that 80% of these unusually hot periods are due to human-caused climate change.

What are the dangers of heatwaves?

While heatwaves may not seem as dramatic as other extreme weather events on the surface, and some people even look forward to them in the UK, they can be extremely deadly when they lead to heat stress, particularly in the vulnerable and elderly.

The heatwave that occured in the UK in 2003 caused an estimated 2000 excess deaths, while extreme heat is believed to be the deadliest form of extreme weather in the US, causing more deaths than hurricanes and floods combined; more than twice as many deaths as tornadoes; and more than four times as many as from extreme cold.

Aside from directly causing excess deaths, extreme heat can also increase the risk of other types of disasters such as drought and wildfires. The heat island effect, where heat is slowly released from infrastructure, can also keep cities incredibly hot.

Heatwaves can also damage our food supply as they negatively impact the health of crops and livestock. Access to electricity can also come under threat during periods of extreme heat, as the demand for cooling increases and power lines come under stress from the heat.

Countries around the world need to prepare for more frequent heatwaves as the climate crisis accelerates. Cities like Athens are already implementing green solutions to help combat extreme heat.

Those in a position of authority must create extreme heat action plans in advance, increase access to cooling, install more green roofs and green spaces to limit the heat island effect, plant trees to provide shade and cool the surrounding air and increase energy efficiency.

We must also act now to stop burning fossil fuels so that we can limit carbon emissions and truly tackle the climate crisis head on.

We hope this guide to the relationship between heatwaves and climate change has been useful. You can help us support charities who are tackling the effects of extreme heat across the globe and working with authorities to be proactive about preparing for climate change, including Oxfam, WaterAid and UNICEF. Simply use SearchScene as your main browser!