Experts stress on adaptation in face of extreme heatwaves
Whether the March-April extreme heatwave spell in India happened solely because of the climate crisis is now an obsolete question because most extreme heatwave events globally are to a large extent because of the climate crisis -- and heatwaves of this scale almost certainly wouldn’t have happened in the pre-industrial world (1750 to 1850), top scientists argued in a recent essay.
In the face of the climate change-led extreme heatwaves, attribution science should focus on upper limits of adaptation and prepare communities for unknown climatic extremes of the future, the scientists specialising in attribution science, a field of research which helps understand if an extreme weather event happened due to the climate crisis, wrote in Springer journal on Monday.
“Citizens in many countries are now experiencing record-smashing heatwaves that were intensified due to anthropogenic climate change. Whether today’s most impactful heatwaves could have occurred in a pre-industrial climate, traditionally a central focus of attribution research, is fast becoming an obsolete question. The next frontier for attribution science is to inform adaptation decision-making in the face of unprecedented future heat,” the essay in Springer journal by scientists from New Zealand Climate Change Research Institute, Victoria University of Wellington; Center for Health and the Global Environment, University of Washington; and Grantham Institute, Imperial College London said.
The heatwave spell over India began in March. It lasted from March 11 to 19, March 27 to April 12, April 17 to 19, and April 26 to 30. In April, several parts of northwest India recorded temperatures above 45°C. Around 14 stations in different parts of the country made temperature records in April. India, on average, recorded its warmest March days in 121 years with the maximum temperature across the country clocking in at 1.86°C above normal, an analysis by IMD had shown. Northwest and central India have experienced the hottest April this season in 122 years.
“Attribution studies have been crucial in demonstrating that extreme weather events in several regions, particularly heatwaves, floods, and cyclones are occurring due to climate change. Now, we are past the phase of asking if each of these extreme weather events is due to climate change and focus on mitigation and adaptation. The question has become obsolete and a frequent distraction from working towards climate change solutions. The frequency, intensity, duration, and area covered by these heatwaves are increasing and set to intensify further in the future, and there is sufficient data and research to establish that,” said Mathew Roxy Koll, climate scientist at Indian Institute of Tropical Meteorology responding to the essay.
There is now increasing agreement among scientists that the March-April heatwave over the Indian subcontinent is also an amplification of climate change. “We’re still working on answering how large the role of climate change in the ongoing heatwave in South Asia is, but here is how the results will be useful beyond assessing current impacts & inform adaptation to extreme heat,” Friederike Otto, co-author of the essay tweeted referring to the paper on Monday.
Extreme event attribution science emerged as a new field of research after a 2004 paper in Nature journal demonstrated that an extreme heatwave in Europe in 2003 which killed around 70,000 people was more severe and at least twice as likely to have occurred because of climate change. Event attribution studies mainly revolve around quantifying whether and to what extent an extreme weather event was more likely to occur in today’s climate, relative to a world without anthropogenic greenhouse gas emissions in the pre-industrial era. Such event attribution studies have also been used for litigation action against fossil fuel companies by quantifying attributable damages. “As global temperatures continue to rise at record-breaking rates, a framework that contextualises the present day against a pre-industrial climate remains relevant to questions of causation and responsibility, but becomes less and less relevant to adaptation decisions,” the scientists write.
Attribution studies have already demonstrated that due to the climate crisis, heatwaves are worsening many times faster than any other type of extreme weather event. For instance, the distribution of temperatures has shifted dramatically after only one degree of global warming; there will likely be no reference for future heat extremes in the temperature distributions of a pre-industrial climate for many regions, the paper said.
Over 500 excess deaths were recorded in British Columbia following a severe heatwave in June 2021; and at least 2,500 people died in the UK due to extreme heat in 2020. India’s National Disaster Management Authority (NDMA) is yet to release the number of deaths in India during the March-April heatwave. The numbers of heat-related deaths are poorly estimated in low- and middle-income countries, but are likely to be significant and unlikely to be decreasing due to urbanization, informal settlement growth and limited implementation of heatwave action plans, the scientists said in the paper.
The authors have called for focus on quantifying heat-related risks from additional warming of half a degree which is when the 1.5°C global warming threshold is crossed, heatwave attribution at sub-city level where the urban heat island phenomenon is common, and projections of severity of future heatwaves that can guide policy making.
“Heatwaves can place electricity networks under immense strain, with blackout risks particularly high in countries where energy demand for cooling can overwhelm less reliable infrastructure networks. By identifying the severity of extreme heat required for power failures to take place in different cities of the world, attribution analyses could then quantify how the probability of exceeding this threshold will change under future warming scenarios,” the paper said. India saw this happening this year with large parts of the country affected by load shedding in extreme heat when people need cooling the most. The wheat crop was also affected to heat extremes over northwest India leading to cascading effects of the heatwave spell.
“Heatwaves have been occurring in India in heatwave-prone pockets. It’s a matter of natural climate variability. But a 2004 attribution study managed to conclude that the 2003 heatwave in Europe that killed thousands of people is likely to have been caused by climate change. Attribution studies are very important so that there is more focus on adaptation and policy making to adapt to the changing climate. Unfortunately, in India such studies are not done. Heatwaves of extreme intensity or very long duration etc are likely to be due to climate change and not natural variability alone. My feeling is that the recent heatwave spell in India is a result of climate change. I don’t have any data to back it but that’s my reading of the recent heat extremes in India,” said M Rajeevan, former secretary, ministry of earth sciences.