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Heatwaves and climate change: what’s going on?

profile picture of Elizabeth Rogers
Associate Clinical Director, Bupa Health Clinics
10 August 2021

In July, the Met Office issued the first ever amber extreme heat warning in the UK. While many of us love the sunshine, more hot weather isn’t good news. And, one of the reasons for the heat warning was to raise awareness about the dangers of extreme heat.

Climate change is causing more changes in temperatures and weather conditions, and they’re lasting for longer. Here I explain more about what this means and how you can keep yourself and others safe in the heat.

What is a heatwave?

The Met Office defines a UK heatwave as three or more days where the maximum daily temperatures have met or gone higher than the heat wave temperature threshold. The heat wave temperature threshold is a range of temperatures that vary depending on where you are in the UK. The threshold is:

  • between 26 and 28°C in the south of England
  • 25°C in the rest of the country

Heatwaves happen in the summer and may also come with high humidity. High humidity is when there is a large amount of water vapour in the air. This can affect your body’s ability to cool down. It feels uncomfortable because the air can’t evaporate your sweat very easily.

What is an extreme heat warning?

The definition of an extreme heat warning is a bit different to a heatwave. Rather than being based on specific temperatures, it’s based on the impact the weather will have on our health and everyday lives. In short, it’s a message to let the general public know when the weather conditions may be harmful. They are called extreme weather warnings, so this could be for heat or other conditions too, such as rain and snow. This can help us all to keep ourselves and others safe.

What does amber mean?

An extreme heat warning is either amber or red.

Amber means that:

  • older people, children and people with underlying health conditions may be particularly affected by the heat
  • your daily routine and how you work may need to change to accommodate the heat
  • travel delays are more likely to happen
  • the heat might affect services to your home and workplace, such as power cuts

Why is extreme heat dangerous to our health?

Hotter weather and extreme heat are dangerous in many ways – both in the short and long term. They include:

  • sun burn
  • heat stroke (a serious condition in which your body becomes too hot and can’t cool down)
  • heat exhaustion (dizziness, feeling sick, weak and dehydrated)
  • skin cancer
  • increased risk of cardiovascular disease and worsening symptoms of breathing related conditions such as COPD.
  • increase in allergies and infectious diseases
  • affecting vulnerable groups at risk including pregnancy, babies, children and people with underlying health conditions

Why is the world getting hotter?

The earth’s surface temperature has risen by 1°C since the pre-industrial period (1850 to 1900). Since the industrial revolution, the amount of greenhouse gases, such as carbon dioxide, in the atmosphere has increased. This increases the chances of heatwaves and longer periods of hotter weather.

In fact, a study found that the chances of heatwaves, such as the one that happened in 2018, is now 30 times higher than it would have been without the climate changes we’ve caused.

  • Temperatures in 2018 reached 35.6°C.
  • In July 2019, temperatures reached as high as 38.7°C.

Experts have predicted that there’s around a 50 percent chance that hot summers like this will become the norm by 2050.

How can I protect myself and others?

Follow these tips for keeping cool in the heat.

Stay out of the sun and practise sun safety

  • Follow the guidance for staying safe in the sun.
  • Wear a hat, sunscreen and sunglasses.
  • Stay out of the sun during the hottest times of the day.

Cool your skin down

  • Wear a wet t-shirt – this will help heat escape through your skin.
  • Put your feet in cold water.
  • Take a cool shower.
  • Put your hot water bottle in the freezer. Use a separate bottle for this purpose as freezing can erode the seal which is dangerous if you then fill it with hot water in winter.

Keep your environment cool

  • Draw the curtains in the day.
  • Open windows at night.
  • Turn off lights in your house (as they produce heat).
  • Put thinner sheets on your bed.

Adapt to the heat

  • Keep your working environment cool.
  • Change your exercise routine, for example, run on an indoor treadmill rather than outside in the midday heat.
  • Slow down – the heat is tiring, take things a bit easier.

Keep hydrated


Stay safe if you’re swimming

In the hot weather more people take to the seas and other open or ‘wild’ swimming spots. If you go be safe and follow the guidelines. For example, swim where there is a lifeguard, and make sure someone knows where you are.

Know how to treat heat-related illness

  • Dehydration and overheating. Drink plenty of water, get out of the sun and cool yourself down.
  • Heat exhaustion. Rest, get into a cool place, drink plenty of water and lie down. Seek medical help if your symptoms don’t improve.
  • Heat stroke. This is very serious and an emergency. Symptoms include confusion, clumsiness, blurred vision, dizziness, headache and rapid pulse. Phone for an ambulance and cool yourself or the person down, for example, get into a cold-water bath.

Plan ahead

When the weather is extreme, look out for the warnings and plan ahead to keep yourself and other safe.

Take climate action

There’s never been a more important time to learn more about climate change and how to take action.

profile picture of Elizabeth Rogers
Dr Elizabeth Rogers
Associate Clinical Director, Bupa Health Clinics

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