PARIS: The devastating heat wave that has gripped India and Pakistan over the past two months is unprecedented, but the worst – possibly much worse – looms on the horizon as climate change continues to steady pace, said top climatologists.
Even without further global warming, South Asia is statistically ripe for a “big one” in the same way that California would be late for a major earthquake, according to a study published this week.
Extreme heat across much of India and neighboring Pakistan in March and April exposed more than a billion people to scorching temperatures well over 40 degrees Celsius (104 degrees Fahrenheit). The hottest part of the year is yet to come.
“This heat wave is likely to kill thousands of people,” tweeted Robert Rohde, senior scientist at Berkeley Earth, a nonprofit climate science research organization.
A devastating heat wave will affect air quality, electricity and water shortages, agricultural production
The number of excess deaths, especially among the elderly poor, will only become apparent in hindsight.
Mortality from heat waves in India has increased by more than 60% since 1980, according to the country’s Ministry of Earth Sciences.
But “cascading impacts” on agricultural production, water, energy supply and other sectors are already apparent, World Meteorological Organization chief Petteri Taalas said this week.
Air quality has deteriorated and large tracts of land are at extreme fire risk.
Blackouts last week as electricity demand hit record highs served as a warning of what could happen if temperatures were to climb further.
For climatologists, none of this came as a surprise.
“What I find unexpected is that most people are shocked, given how long we have been warned of the arrival of such disasters,” said Camilo Mora, professor at the University of Hawaii. .
“This region of the world, and most other tropical areas, are among the most vulnerable to heat waves.”
The new normal
In a landmark 2017 study, Mora calculated that almost half of the world’s population will be exposed to “deadly heat” 20 or more days each year by 2100, even if global warming is capped at less than two. degrees Celsius, the fundamental goal of the Paris Agreement.
How much is climate change to blame for scorched Earth temperatures easing right now in India and Pakistan? Scientists at Imperial College London’s Grantham Institute, led by Friederike Otto, a pioneer in the science of attribution, calculate the numbers.
“We are still working on the likelihood and intensity of this particular heat wave,” she said. AFP.
“But there is no doubt that climate change is a huge game-changer when it comes to extreme heat,” she added. “What we’re seeing right now will be normal, if not cool, in a 2C to 3C world.” The Earth’s surface, on average, is 1.1 C above pre-industrial levels. National carbon reduction commitments under the Paris Agreement, if met, would see the world warm another 2.8 degrees.
In India and Pakistan, “more intense, longer duration and higher frequency heat waves are predicted,” the Intergovernmental Panel on Climate Change (IPCC) said in a recent report. historical report.
“Before human activities raised global temperatures, we would have seen the heat that hit India about once in 50 years,” said Marian Zachariah, a researcher at Imperial College London.
“But now we can expect such high temperatures about once every four years.” In other words, continued global warming guarantees greater heat extremes in coming decades.
Sunburn inside the body
But things could get even worse sooner, according to a new study published in Science Advances.
A team led by Vikki Thompson of the University of Bristol has ranked the world’s most severe heatwaves since 1960. Their benchmark, however, was not maximum temperatures, but how hot it was compared to what what one would expect for the area.
Surprisingly, South Asia was far from top of the list.
“When defined in terms of deviation from the local norm, heat waves in India and Pakistan to date have not been so extreme,” Thompson explained in a commentary.
By this measure, the worst torrid on record in six decades occurred in Southeast Asia in 1998.
“An equivalent outlier heat wave in India today would mean temperatures above 50C across large swathes of the country,” Thompson said.
“Statistically, a record heat wave is likely to occur in India at some point.” What makes extreme heat deadly are the high temperatures combined with the humidity, a steam bath mix with its own criteria: the wet bulb temperature (WB).
When the body overheats, the heart speeds up and pumps blood to the skin where sweating cools it. But above a threshold of heat plus humidity, this natural cooling system stops.
“Think of it like sunburn but inside your body,” Mora said.
A wet bulb temperature of 35°C WB will kill a healthy young adult within six hours. Last week, the central Indian city of Nagpur briefly recorded 32.2 WB.
“The increase in heatwaves, floods, cyclones and droughts that we have seen in this region so far is due to a single degree Celsius,” said Roxy Mathew Koll, a climatologist at the Indian Institute of tropical meteorology. AFP.
“It’s hard for me to even imagine the impacts when the increase in global temperatures doubles.”
Posted in Dawn, May 7, 2022