Deadly heatwaves could affect 75 per cent of the planet

In Health


A shocking study paints a bleak future for humanity in which three quarters of the world’s population will be exposed to deadly heatwaves by the end of the century. 

Experts based their predictions on carbon dioxide emissions continuing to rise at current rates, a conservative estimate.

Even if emissions are aggressively reduced around half of the world’s population would still be affected, according to the research.

It comes as vicious heatwave is set to bake California, Arizona and Nevada as temperatures soar to 124 degrees in Death Valley. 

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Scientists have used data on deaths caused by heatwaves and predictions based on carbon dioxide emissions continuing to rise at current rates to model the future risks posed by lethal heatwaves (pictured), which could affect 74 per cent of the world's population by 2100

Scientists have used data on deaths caused by heatwaves and predictions based on carbon dioxide emissions continuing to rise at current rates to model the future risks posed by lethal heatwaves (pictured), which could affect 74 per cent of the world's population by 2100

Scientists have used data on deaths caused by heatwaves and predictions based on carbon dioxide emissions continuing to rise at current rates to model the future risks posed by lethal heatwaves (pictured), which could affect 74 per cent of the world’s population by 2100

PLACES AT RISK OF DEADLY HEATWAVES 

Scientists at the University of Hawaii have used data on deaths caused by heatwaves to identify a threshold beyond which high temperatures and humidity become deadly.

By using predictions based on carbon dioxide emissions continuing to rise at current rates, they have modelled the future risks posed by heatwaves.

Worldwide, the greatest risk to human life is projected for tropical areas.

This is because the tropics are hot and humid all year round, whereas at higher and lower latitudes the risk of deadly heat is restricted to the summer.

New York is among the cities affected, with around 50 days predicted where climate conditions exceed deadly thresholds.

Elsewhere, Sydney will experience these extreme conditions for 20 days, Los Angeles for 30, and Orlando and Houston will be affected for the duration of the summer.

Scientists at the University of Hawaii at Manoa studied over 1,900 locations worldwide where high temperatures have killed people since 1980.

By analysing the climatic conditions which caused 783 deaths, the team identified a threshold beyond which heat and humidity become deadly.

Currently, about 30 per cent of the world’s human population is exposed to these potentially lethal conditions each year.

By 2100, this will rise to least 48 per cent if greenhouse gases are aggressively reduced.

At current rates, this will rise to 74 per cent and the figures could be even higher if emissions rise, which is likely with the development of economies around the world.  

Dr Camilo Mora, associate professor of geography at the university and lead author of the study, said: ‘Our attitude towards the environment has been so reckless that we are running out of good choices for the future

‘We are running out of choices for the future. For heatwaves, our options are now between bad or terrible.

‘Many people around the world are already paying the ultimate price of heatwaves, and while models suggest that this is likely to continue to be bad, it could be much worse if emissions are not considerably reduced.’

The human body can only function within a narrow range of core body temperatures, around 37 degrees Centigrade (98.6 degrees Fahrenheit).

The scientists  studied over 1,900 locations worldwide where high temperatures have killed people since 1980 (pictured). By analysing the climatic conditions which caused 783 deaths, the team identified a threshold beyond which heat and humidity become deadly

The scientists  studied over 1,900 locations worldwide where high temperatures have killed people since 1980 (pictured). By analysing the climatic conditions which caused 783 deaths, the team identified a threshold beyond which heat and humidity become deadly

The scientists studied over 1,900 locations worldwide where high temperatures have killed people since 1980 (pictured). By analysing the climatic conditions which caused 783 deaths, the team identified a threshold beyond which heat and humidity become deadly

A web-application (above) allows you to check any location on Earth and the number of days in a year when conditions exceed the deadly threshold, based on current emissions (RCP8.5), moderate reductions (RCP4.5) and extreme reductions (RCP2.6)

Heatwaves pose a considerable risk to human life because hot weather, aggravated with high humidity, can raise body temperature leading to a life threatening condition known as hyperthermia.

From over 30,000 relevant publications, the researchers identified 911 papers with data on 1,949 case studies of cities or regions, where human deaths were associated with high temperatures.  

When analysing the climatic conditions for those cities, the researchers discovered a common threshold beyond which temperatures and humidities became lethal.

Projected daily conditions of temperature and humidity for New York (left) and Jakarta (right) in relation to the threshold (red thick line) beyond which people have died in the past. Results are by 2100 under current emission levels

Projected daily conditions of temperature and humidity for New York (left) and Jakarta (right) in relation to the threshold (red thick line) beyond which people have died in the past. Results are by 2100 under current emission levels

Projected daily conditions of temperature and humidity for New York (left) and Jakarta (right) in relation to the threshold (red thick line) beyond which people have died in the past. Results are by 2100 under current emission levels

Pictured - Temperatures and humidities during lethal heat events (black crosses). The blue line indicates the threshold between lethal and non-lethal events. To be conservative, the study used a more severe threshold (red line)

Pictured - Temperatures and humidities during lethal heat events (black crosses). The blue line indicates the threshold between lethal and non-lethal events. To be conservative, the study used a more severe threshold (red line)

Pictured – Temperatures and humidities during lethal heat events (black crosses). The blue line indicates the threshold between lethal and non-lethal events. To be conservative, the study used a more severe threshold (red line)

 STUDY METHODS

Heatwaves pose a considerable risk to human life because hot weather, aggravated with high humidity, can raise body temperature leading to a life threatening condition known as hyperthermia.

From over 30,000 relevant publications, the researchers identified 911 papers with data on 1,949 case studies of cities or regions, where human deaths were associated with high temperatures.

When analysing the climatic conditions for those cities, the researchers discovered a common threshold beyond which temperatures and humidities became lethal.

A web-application accompanying the paper allows you to check, for any place on Earth, the number of days in a year when temperature and humidity exceed such a deadly threshold.

A web-application accompanying the paper allows you to check, for any place on Earth, the number of days in a year when temperature and humidity exceed such a deadly threshold. 

Worldwide, the greatest risk to human life is projected for tropical areas. 

This is because the tropics are hot and humid all year round, whereas at higher and lower latitudes the risk of deadly heat is restricted to the summer.

New York is among the cities affected, with around 50 days predicted where climate conditions exceed deadly thresholds.

Elsewhere, Sydney will experience these extreme conditions for 20 days, Los Angeles for 30, and Orlando and Houston will be affected for the duration of the summer.  

‘Warming at the poles has been one of the iconic climatic changes associated with the ongoing emissions of greenhouse gases’ says Iain Caldwell, a post-doctoral researcher at the university and another author of the paper.

‘Our study shows, however, that it is warming in the tropics what will pose the greatest risk to people from deadly heat events. 

‘With high temperatures and humidities, it takes very little warming for conditions to turn deadly in the tropics.’ 

The full findings of the study were published today in the journal Nature Climate Change.

CLIMATE CHANGE IS TURNING ANTARCTICA GREEN 

The pristine white landscape of Antarctica has disappeared.

Plant life is growing rapidly due to climate change turning the continent green.

Few plants live on Antarctica but scientists studying moss have found a sharp increase in biological activity in the last 50 years. 

A study released in May claims the rate of moss growth is now four to five times higher than it was pre-1950.

Plant life is growing rapidly due to climate change turning the continent green. Few plants live on Antarctica but scientists studying moss have found a sharp increase in biological activity in the last 50 years 

Plant life is growing rapidly due to climate change turning the continent green. Few plants live on Antarctica but scientists studying moss have found a sharp increase in biological activity in the last 50 years 

Plant life is growing rapidly due to climate change turning the continent green. Few plants live on Antarctica but scientists studying moss have found a sharp increase in biological activity in the last 50 years 

A team including scientists from the University of Exeter used moss bank cores – which are well preserved in Antarctica’s cold conditions – from an area spanning about 400 miles.

They tested five cores from three sites and found major biological changes had occurred over the past 50 years right across the Antarctic Peninsula. 

Recent climate change on the Antarctic Peninsula is well documented with warming and other changes such as increased precipitation and wind strength.

Weather records mostly began in the 1950s but biological records preserved in moss bank cores can provide a longer-term context about climate change.