Scorched earth ! Report paints grim outlook for global population, heatwaves

According to new research, unless carbon emissions are controlled, up to 75% of the world population could literally 'take the heat' in the form of deadly heat waves by 2100.

Heat stroke - Image Credit: Miriam Doerr Martin Frommherz / Shutterstock

Heat stroke - Image Credit: Miriam Doerr Martin Frommherz / Shutterstock

The study published yesterday in the journal Nature Climate Change has found that 30 percent of the world’s population is exposed to heat waves that could be lethal for around 20 days per year or more. This heat wave is on the move and much like a spreading forest fire is affecting more and more people every year. There needs to be an urgent major reduction of carbon emissions and greenhouse gases such as carbon dioxides researchers and experts believe. Without that three fourths of the population would face death due to heat by 2100 say researchers. The analysis sounds grim when it says that despite reductions, 50% still face the risk of extreme heat that is capable of killing for at least 20 days a year or more.

Camilo Mora of the University of Hawaii at Manoa, the study’s lead author says "for heatwaves, our options are now between bad or terrible, these deadly heat waves are becoming common", and she expressed surprise that no major concern is shown regarding these impending dangers. The 2003 European heatwave alone killed nearly 70,000 people – a number greater than those dying in the 9/11.

Other deadly heatwaves of the past include 2010 Moscow heatwave that killed at least 10,000 people and further back, 1995 Chicago heatwave that killed 700 people. More recently heatwaves in India and Pakistan have claimed dozens of lives in the last two weeks where temperatures at some places rose to a record 128 degrees Fahrenheit (53.5 degrees Celsius). Deadly heat wave reports are also in from Washington, D.C., New York City, Chicago, Los Angeles, Toronto, London, Sydney, Beijing, Tokyo, and São Paulo.

The study was conducted by Mora and an international group of researchers and students who systematically looked at more than 30,000 relevant publications. They extracted 1,949 case studies from cities and areas where human deaths have been caused by high temperatures.

From this data the researchers used model simulations to predict what might happen to the climate scenarios under several conditions. From these results the predictions show one in two persons dying of heat wave related causes despite all efforts at reduction of carbon emissions and three in four dying if the present scene continues.

They note that risk of deaths is higher in populations living in wet tropics where minor rises of temperatures are enough to result in deaths. Mora explained that not only high rise of temperatures but also moderate rise in temperatures of less than 86 degrees Fahrenheit (30 degrees Celsius) when combined with high humidity can lead to deaths.

The human body’s internal thermostat is set between 98.6 to 100.4 degrees Fahrenheit (37 to 38 degrees Celsius). Warmer than that is termed as fever and as the temperature of the surroundings rise the body starts to sweat to cool off. At 104 degrees Fahrenheit (40 degrees Celsius) and above there is risk of internal damage and medical attention is vital. Heat index is a measure that combines temperature and humidity. Once that reaches 104 degrees Fahrenheit (40 degrees Celsius), there is risk of heat related deaths.

Who is at risk of heat stroke?

People who develop heat stroke easier than others include:

  • children below two years,
  • very old persons,
  • disabled persons,
  • those with heart, kidney or other problems,
  • those with diabetes who take regular insulin,
  • those who have taken too much alcohol are at risk since alcohol causes dehydration,
  • those taking certain drugs and medications, such as antipsychotics and beta-blockers are also at risk.


Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.


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