The sun hangs over London, silhouetting tall buildings such as the Gherkin

London is up to 10⁰C warmer than the surrounding countryside, which exacerbates the effect of heat waves. Image © borrdephong.r/Shutterstock

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Risks to human health are increasing because of climate change

Heatwaves are growing more common as the effects of climate change make themselves known.

With the UK facing the possibility of temperatures over 40°C for the first time, the effect of extreme heat on human health may require changes in our behaviour, mindset and the spaces we live in.  

High temperatures across the UK have prompted the Met Office to issue its first ever red warning for extreme heat for next week amid concern over the impact on human health.

The warning, which covers parts of England from London to Manchester, means there is a risk of serious illness or danger to life from the heat, amid predictions that temperatures could pass 38.7°C - the highest temperature ever recorded in the UK.

Dr Nikos Christidis, climate attribution scientist at the Met Office, says, 'We hoped we wouldn’t get to this situation but for the first time ever we are forecasting greater than 40°C in the UK.'

'In a recent study we found that the likelihood of extremely hot days in the UK has been increasing and will continue to do so during the course of the century, with the most extreme temperatures expected to be observed in the southeast of England.  Climate change has already influenced the likelihood of temperature extremes in the UK.

'The chances of seeing 40°C days in the UK could be as much as 10 times more likely in the current climate than under a natural climate unaffected by human influence. The likelihood of exceeding 40°C anywhere in the UK in a given year has also been rapidly increasing, and, even with current pledges on emissions reductions, such extremes could be taking place every 15 years in the climate of 2100.'

Advice on how to face the high temperatures has been issued, amid ongoing concern over how climate change will affect human health as the planet keeps warming. 

Dr Agostinho Sousa, Head of Extreme Events and Health Protection at UK Health Security Agency (UKHSA), says, 'Heat-health alerts have now been issued to the majority of the country, with temperatures set to remain consistently high throughout the duration of this week.'

'Most of us can enjoy the hot weather when it arrives, but it is important to keep yourself hydrated and to find shade where possible when UV rays are strongest, between 11am and 3pm.'

'If you have vulnerable family, friends and neighbours, make sure they are aware of how they can keep themselves protected from the warm weather.'

A car exhaust emitting grey fumes

Increased temperatures, alongside UV energy, allow the formation of ground-level ozone from combustion fumes. Image © Paolo Bona/Shutterstock

How does climate change affect human health?

Earth is currently expected to warm by 2.4⁰C by 2100 if the nations of the world do not improve their emission cuts in the next decade. While a route to below 1.5⁰C of warming is possible, as targeted by the Paris Agreement, this requires fast and deep cuts to the amount of greenhouse gases being produced.

In any event, the world will be significantly warmer throughout the 21st century. Cities and other built-up areas will bear the brunt of this warming, with the lack of vegetation and bare soil causing these areas to absorb more heat - a phenomenon known as the urban heat island effect.

This can cause urban areas to become 3-4⁰C hotter than surrounding areas. In London, one of the largest cities in the world, the effect could be more than doubled, with areas such as Shepherd's Bush and Peckham predicted to face an increased risk of extreme heat as the century progresses.

High temperatures can directly impact human health, ranging from cramps and heat exhaustion to heatstroke and hyperthermia. The elderly, outdoor workers and children are among the most at risk, with an average of 800 people every year dying in England and Wales as a result of heat, a figure which will grow as the world warms.

Extreme heat can also cause a reaction in air pollutants, producing ground-level ozone. This gas can exacerbate asthma and cause lung damage, with one study suggesting that deaths associated with ozone formed by climate change have increased by 5% in 20 years.

Aside from direct impacts, climate change affects human health in other ways. Extreme weather events such as droughts, storms and wildfires have all been linked to a changing climate, putting communities at risk.

Meanwhile, higher temperatures change how diseases spread by altering where animal and plant species live. Within mammals alone, 15,000 diseases could cross into new species in the next 50 years, including humans. Meanwhile, changes in the migratory patterns of birds may allow avian diseases such as bird flu to evolve and spread in unexpected ways.

The effects of increased temperatures on wildlife also threaten a loss of biodiversity if species decline or become extinct, which in turn can affect human health. The loss of pollinators, natural environments and airborne microbes can affect food security, the spread of disease and air quality. 

Two tower blocks with green roofs

Changes to how we design our buildings, such as the inclusion of more vegetation, can help to cool cities. Image © Lucas Eduardo Benetti/Shutterstock

How can we protect ourselves from the health impacts of climate change?

While any long-term solution to climate change will require the world to slash its emission of greenhouse gases, there are a number of ways in which we can mitigate effects on human health.

In the short term, small changes in our behaviour can have a significant impact on how well we cope with heat. Working at cooler times of the day, especially when physical activity is involved, and resting during the hottest periods can help to avoid the risk of heat-related illnesses.

These small changes can also affect climate change on a larger scale. A recent study in Australia found that using fans first, rather than turning straight to an air conditioner, saved energy while allowing people to tolerate temperatures 3-4⁰C above their normal limit.

The researchers estimated that this could lead to a 76% reduction in the carbon emissions produced by air conditioner use, cutting the entire country's carbon footprint by over two million tonnes of carbon dioxide.

These changes can be aided by adjustments to the design of new buildings and urban areas. A new report from the Environment Agency noted that including plants in urban design, such as tree planting and the use of green roofs, can reduce the impact of the urban heat island effect as well as removing pollution from the air.

Some organisations have called for new strategies to raise awareness of extreme heat, and more research. The Physiological Society has called for heatwaves to be named by the Met Office in a similar way to storms to highlight how dangerous they can be.

Society fellow Professor Mike Tipton says, 'Extreme heat isn't just a problem on your summer holidays, due to climate change we are increasingly seeing very hot weather here in the UK. Even one day of very hot weather can present a risk, but consecutive days of high temperatures triggers a heatwave that requires specific actions to keep people safe.'

'Naming heatwaves like storms makes the risk to health clear and underlines that people can't expect to continue as normal during the heatwave. This will aid the communication of approaching heatwaves through the media and government agencies, which is especially helpful for those who don't have as ready access to the internet or weather apps on smartphones.'

Other strategies to mitigate the effect of climate change on human health will require further research. This could include studying exactly how high temperatures affect the human body and developing personal protective equipment to help us deal with it on a regular basis.

These represent just some of the steps that countries around the world will need to take to adapt to the warmer world we've created.