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Mahesh

11/10/23 05:58 AM IST

2.2 billion people could face heat waves beyond survival limit: Study

In News
  • Delhi, Kolkata, Lahore, Dhaka, Shanghai and Beijing are expected to start recording considerable “hot hours” annually.
Major Findings
  • India and the Indus Valley will experience the first deadly moist heat waves and, subsequently, substantial increases in accumulated hot hours per year, a new paper published in Proceedings of the National Academy of Sciences has said.
  • Indian cities such as Delhi and Kolkata, Pakistan’s Lahore, Bangladesh’s Dhaka, China’s Shanghai and Beijing are expected to start recording considerable “hot hours” annually even at 1.5 and 2 degree C warming over pre-industrial levels.
  • For example, Delhi is projected to record 16 annual hot hours at 1.5°C warming which increases to 39 hot hours at 2°C and 170.7 hot hours at 3°C warming.
  • Still, limiting warming to under 2°C nearly eliminates exposure and risk of widespread uncompensable moist heatwaves as a sharp rise in exposure occurs at 3°C of warming.
  • Parts of the Middle East and the Indus River Valley experience brief exceedances with only 1.5°C warming.
  • More widespread, but brief, dangerous heat stress occurs in a +2°C climate change scenario, including in eastern China and sub-Saharan Africa, while the US Midwest emerges as a moist heat stress hotspot in this projection.
  • If global temperatures increase by 2°C above pre-industrial levels, 2 billion residents of Pakistan and India’s Indus River Valley, the one billion people living in eastern China and the 800 million residents of sub-Saharan Africa will annually experience many hours of heat that surpass human tolerance.
  • These regions would primarily experience high-humidity heatwaves.
  • As people get warmer, they sweat, and more blood is pumped to their skin so that they can maintain their core temperatures by losing heat to the environment.
  • At certain levels of heat and humidity, these adjustments are no longer sufficient, and body core temperature begins to rise.
  • This is not an immediate threat, but it does require some form of relief. If people do not find a way to cool down within hours, it can lead to heat exhaustion, heat stroke and strain on the cardiovascular system that can lead to heart attacks in vulnerable people.
  • The worst heat stress will occur in regions that are not wealthy and that are expected to experience rapid population growth in coming decades.
Source- Hindustan Times

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