Disasters explained: heatwaves

Everything you need to know about heatwaves

Heatwaves and intense hot weather can be extremely dangerous for people.

In fact, it’s one of the most dangerous types of weather-related hazards, with 166,000 people dying from extreme hot weather between 1997-2017. It can cause dehydration, blood clots and induce heatstroke.

Here, you can read and learn more about what they are, why they happen and what their link is to climate change.

Although we have never needed to respond to a heatwave, ShelterBox provides emergency shelter following different types of disasters. This includes droughts, tropical storms and other climate related disasters.

What is a heatwave and why does it happen?

Does climate change cause heatwaves?

What are the effects of heatwaves?

How can I protect myself during a heatwave?

What is a heatwave and why does it happen?


A heatwave is a period of unusually hot weather, often lasting several days. 

According to the Met Office, a heatwave is an extended period of hot weather relative to the expected conditions of the area at that time of year. The effects are more severe when accompanied by high humidity.

 

Heatwaves usually occur in the summer when we are more likely to see high pressure weather systems. High-pressure systems force air downward, trapping warm ground air in place. This force prevents air from rising and as a result there is nothing to prevent the hot air from getting hotter.

High pressure systems are slow moving and can persist for a prolonged period of time, such as days or weeks.

Does climate change cause heatwaves?


Heatwaves are extreme weather events. Scientists believe that climate change is making heatwaves more severe and more frequent.

A higher concentration of carbon dioxide (CO2) in the atmosphere is making heatwaves more common now than before the industrial revolution. When CO2 builds up in the atmosphere, it traps in heat like a blanket, causing the Earth’s temperature to rise.

As greenhouse gas emissions continue to increase, heatwaves are expected to occur more often and at higher intensity.

thermometer showing high temperature during a heatwave
In England, there are about 2000 heat-related deaths every year (source: NHS).

What are the effects of heatwaves?


sunset
As greenhouse gas emissions continue to increase, scientists warn that heatwaves will occur more frequently.

Heatwaves kill thousands of people each year, while more suffer serious health impacts that can linger long after it has passed.

In fact, extreme heat kills more people in the U.S. each year than any other kind of natural hazard (source: National Geographic). In England, the NHS records an average of 2000 heat-related deaths every year.

Vulnerable groups such as very young children, the elderly and people with existing health issues are more likely to experience the impacts of extreme heat because they find it harder to maintain their core body temperature.

Moreover, heatwaves can put a strain on health and emergency services. People are more likely to use more water and energy to run electric cooling systems such as air conditioning units or fans. This increases strain on water, energy and transportation that can cause power shortages or even blackouts. Extreme heat can also affect food security and livelihoods, with crops and livestock being compromised.

How can I protect myself during a heatwave?


There are several simple things you can do to protect yourself during a heatwave.

  • Drink lots of water and fluids, avoiding alcohol as it can cause further dehydration.
  • Avoid exercising during the hottest hours of the day.
  • Stay cool indoors. If you must go outside, stay in the shade and take water with you.
  • Make sure to check on your loved ones who might be vulnerable during a heatwave, like elderly relatives or very young babies.
  • If you have pets, make sure they drink lots of water and keep cool, under shade.

Follow advice from health authorities such as the NHS for more tips on how to cope during a heatwave.

Sources and references: Met Office, WHO, National Geographic, New York Times, BBC, NHS.

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