Big cities likely to witness catastrophic heatwaves should planet warm 3 degrees: Study

Amid increasing heat waves due to climate change that is increasingly posing a threat to life, researchers warn of a "life or death" situation for major cities should the planet turn 3 degrees Celsius warmer than pre-industrial levels.

The research shared by scientists at the World Resources Institute (WRI) reveals what could happen in nearly 1,000 big cities if the temperaturekeeps warming at current rates. Over 2.1 billion are likely to be affected adversely in these cities.

Scientists cautioned on Thursday that heatwaves are expected to become more frequent with longer duration. The demand for air conditioners would rise, just as widespread illnesses would increase.

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"At 3 degrees C of warming, many cities could face month-long heatwaves, skyrocketing energy demand for air conditioning, as well as a shifting risk for insect-borne diseases — sometimes simultaneously," the authors wrote.

In 2005, global warming was limited to 1.5 degrees Celsius after 200 nations agreed in Paris to prevent the catastrophic consequences of climate change. According to the latest UN assessments, the cap today would be at 2.9 degrees Celsius to combat climate change.

"The difference between 1.5 degrees C and 3 degrees C has life-or-death consequences for billions of people worldwide," said Rogier van den Berg of WRI, an America-based think tank.

Low-income nations to be more exposed

The report highlights that fast-growing cities in low-income nations would face the worst consequences of rising temperatures. Poorest cities remain more exposed as they lack the means to adapt to rising temperatures.

"People living in low-income cities will be the hardest hit," says the report.

It is predicted that two-thirds of the world's population will reside in cities by 2050. Out of which 90 per cent growth will be seen in African and Asian countries.

Dire consequences

WRI estimated that the longest heatwaves in large cities could prolong to 16.3 days on average every year if the global temperatures rise by 1.5 degrees Celsius. However, they could go on to 24.5 days in a scenario where the average increase is 3 degrees Celsius.

The frequency of heatwaves is also likely to increase from 4.9 to 6.4 on average in a year, which would lead to a massive surge in the demand for air conditioning and energy.

Hotter cities will also provide ideal conditions for mosquitoes, which carry life-threatening arboviruses. The researchers predict that the risk of arbovirus will remain in major cities of Brazil for at least six months at 3 degrees Celsius increased temperatures.

While the number of peak malaria days would likely reduce across the world, the temperate zones in Europe and North America could experience a rise.

Sub-Saharan African capital cities like Dakar, Freetown, and others "could suffer heatwaves of more than a month" seven times a year on average.

"This data should serve as a wakeup call... now is the time to start preparing cities for a much hotter world while doing everything we can to slash emissions," said van den Berg.

(With inputs from agencies)