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Why is it exceptionally hot this year?

TreeTake is a monthly bilingual colour magazine on environment that is fully committed to serving Mother Nature with well researched, interactive and engaging articles and lots of interesting info.

Why is it exceptionally hot this year?

It is now well established that extreme heat has a disproportionate impact on the poor and marginalised, of which there are a large number in India...

Why is it exceptionally hot this year?

Climate change is making heatwaves more frequent and severe, with periods of hot days stretching out longer. What we need is higher resolution data and, more importantly, we need long-term policies. Immediately, we need to plant more trees and shady climbers, and stop all heat-releasing commercial activities in factories etc.

Arunima Sen Gupta

This is the age of climate change and you need no other proof than the early and sudden onset of the summer season that started abruptly and overtook pleasant coolness of early March, and mid-March an intense heatwave had already gripped large parts of India. The heat is breaking all records. The Centre for Science and Environment also warned of severe implications for water security, pointing out that the Northwest and central India experienced their hottest April in 122 years with average maximum temperatures reaching 35.9 and 37.78 degree Celsius respectively. Banda in east Uttar Pradesh logged a record high of 47.4 degrees Celsius by April end while places like Allahabad, Jhansi, Sports Complex, Ganganagar, Nowgong, and Chandrapur have all breaches the 46 degree Celsius mark. According to an analysis by green think tank Centre for Science and Environment, the early heatwaves that began on March 11 have impacted 15 Indian states and union territories. The floods in some states like Assam are not helping the situation but adding to it. Now, most parts are facing not just intense heat but also extreme humid environment.

It will be wise to mention here that a heatwave is declared when the maximum temperature is over 40 degrees Celsius and at least 4.5 notches above normal. A severe heatwave is declared if the departure from normal temperature is more than 6.4 notches, according to the IMD. Based on absolute recorded temperatures, a heatwave is declared when an area logs a maximum temperature of 45 degree Celsius. A severe heatwave is declared if the maximum temperature crosses the 47 degree Celsius mark. With one month to go before the monsoon season, temperatures have already reached 46 degrees Celsius in central and northern India. They hit the highest since 1901 last month. The heat has tested power grids as air conditioners run on full blast and has also threatened wheat crops. Local authorities are implementing action plans to manage health risks and even deaths. “Why is it exceptionally warm this year? The only reason is global warming,” said Roxy Mathew Koll, a climate scientist at the Indian Institute of Tropical Meteorology. “We have looked at data for seventy years and at the intensity, the number of heatwaves is directly in response to global warming.”

Arpita Mondal, a climate researcher at the Indian Institute of Technology Bombay, believes this heatwave is particularly concerning for its timing and its spread as usually, peak temperatures in the region come in May and June, just before monsoon rains bring relief. “But this year has been particularly hot, particularly early. March of this year was the hottest on record, with an average temperature of 33.1 degree Celsius. With equally, in fact more, hot April and May, it has become unbearable,” she added. The affect of climate change and subsequently hot weather has affected not only the typical hot spots in the northwest and southeast but also regions that aren’t used to seeing so much extreme heat. “It is part of a broader climate change signal,” says Amir AghaKouchak, a climate researcher at the University of California, Irvine. India’s average annual temperature increased at a rate of 0.62 degree Celsius per 100 years between 1901 and 2020, according to data from the World Bank. And maximum temperatures have climbed even more quickly, at a rate of 0.99 degree Celsius every 100 years. “People think a degree or two might not matter, but when average temperatures increase by even small amounts, it means extreme events are becoming more likely. The effects of climate change on weather can sometimes be difficult to tease out. But for heat waves, researchers have very high confidence that climate change is making the problem worse,” he explained. However, the World Meteorological Organization said it would be premature to attribute it solely to climate change. In a statement, the WMO said: "It is premature to attribute the extreme heat in India and Pakistan solely to climate change. However, it is consistent with what we expect in a changing climate. Heatwaves are more frequent and more intense and now start earlier than they did in the past.”

Heat can have devastating impacts on human health—356,000 deaths globally in 2019 were linked to extreme heat. The risk is greatest for elderly people and children, but anyone without adequate access to cooling can be affected, especially if heat continues for days at a time without letting up at night.  Even if told in advance to prepare for a very hot season or include early warning systems for residents, training for healthcare professionals, and adjustments to help cool buildings naturally, realities of a developing country mean that many people will still come into harm’s way during heat waves in India as of 2019, only about 7% of Indian households had an air conditioner. And staying inside when temperatures peak might not be an option for people who depend on income from daily work. Cutting emissions will help prevent the worst future warming scenarios, but the current reality is already difficult to endure for many. And India’s deadly heat waves offer just one example of who will be most affected by a changing climate. Here are 1.4 billion people who will be affected by this heat wave, the majority of whom contributed very little to global warming. This phenomenon should put an end to the question of why people should care about climate change, point out experts.

Weather experts have attributed the high temperature across the country to the absence of periodic light rainfall and thundershowers, typical for this time of the year, due to the lack of active western disturbances. “Northwest India saw at least four western disturbances in March and April, but they were not strong enough to cause a significant change in the weather,” said Mahesh Palawat, vice-president (Meteorology and Climate Change), Skymet, a private weather forecasting agency. “The region did not see any significant pre-monsoon activity from March 1 to April 20 which compounded the severity of the successive heatwave spells,” he said, adding it had a ripple effect on central India too. According to D Sivananda Pai of the Kottayam-based Institute for Climate Change Studies, anti-cyclones over western parts of Rajasthan in March and the absence of western disturbances had triggered the early and extreme heatwaves. Anticyclones cause hot and dry weather by sinking winds around high-pressure systems in the atmosphere.  IMD Director General Mrutyunjay Mohapatra has said that northwest and west central parts of the country - Gujarat, Rajasthan, Punjab and Haryana - will continue to experience above normal temperatures in May as well. Nights would be warmer in May in most parts of the country, except for some regions of south peninsular India. However, giving some respite, under the influence of a western disturbance, Rajasthan, Delhi, Punjab and Haryana might witness light rainfall and thunderstorms.

The United Nations’ Intergovernmental Panel on Climate Change had already warned that India was expected to suffer more frequent and intense heatwaves, extreme rainfall and erratic monsoons in the coming decades as the planet warms. Work hours lost to heat waves could cause losses of as much as $250 billion, or 4.5% of gross domestic product, by the end of the decade. For India, the world’s poorest super-emitter, adapting to a hotter Earth is as urgent a task as cutting planet-warming emissions. A recent study showed a 62% rise in heat-related deaths in the last 20 years. An official assessment of climate change published in 2020 showed that the frequency and intensity of droughts and cyclones had significantly increased in the past six decades. The number of days of intense rainfall and the pace at which sea levels are rising have more than doubled over that period. The disasters underscore how countries like India, which are responsible for relatively little of the greenhouse gases accumulated in the atmosphere, often bear the brunt of climate impacts. That means spending billions to protect themselves instead of investing in economic development that could lift millions out of poverty. These countries, especially in Africa, also tend to lack resources to monitor and forecast the weather so they can better prepare for extreme events. India, however, is investing to improve its observational data and computing capabilities to build better climate models. The country’s official weather forecaster managed to cut the number of deaths caused by cyclones to six in 2021 from 10,000 a year in 1999 by making more accurate short-term predictions. Still, the country is racing against the clock as more erratic weather becomes harder to forecast. Worsening climate change is limiting predictability of events.

Heatwave days increasing

The number of heatwave days in India is increasing at a rapid pace every 10 years, an ongoing study by the Met Department showed. From 413 in 1981-90 to 575 in 2001-10 and 600 in 2011-20, the number of days that see extremely hot days is persistently increasing at 103 weather stations, mostly in inland areas, the study showed. The latest numbers, which are yet to be published, are an update of an earlier research at the same weather stations till 2010. The ongoing study also showed most of the 103 weather stations have recorded a significantly increasing trend in heatwave frequency between April and June during the 1961-2020 period, researchers said. “One of the main reasons for this can be attributed to climate change,” said DS Pai, director at the Kottayam-based Institute for Climate Change Studies. “The other reasons for the extreme departure from normal maximum temperatures include local weather conditions and other factors like increasing concretisation, deforestation and changes in land use,” said Pai, who was previously a climate scientist at IMD Pune and had been associated with the study from its inception. The mostly inland regions studied have seen more than eight heatwave days, on average, in the three months from April through June, and the affected areas have increased spatially between 1991 and 2020, compared with the previous three decades starting from 1961. Many of the areas in the core heatwave zone, which include north, northwest, central, east, and northeast peninsular India, recorded the highest number of severe heatwaves in the month of May, the study revealed. “There is no doubt that extreme heat events are increasing in India,” agreed Mahesh Palawat, adding: “Global warming has a primary role in this, although there are several other factors at play as well.”

Himalayas are bearing the brunt too

The high heat in March did not even spare the Himalayan states of Himachal Pradesh and Uttarakhand, which typically experience cooler temperatures during this time, Palawat said, indicating an overall rise in temperatures across the country. This is also borne out by the IMD study that found that the number of cold wave days over the mountainous region has been decreasing over the past three decades, according to Pai. “The past three decades have been the warmest for the country and globally,” he said. “Extreme temperature events like heatwaves are a key feature of global warming.” The IMD research does not consider March temperatures, same as its Climate Hazards and Vulnerability Atlas of India released in January this year. The Atlas, which covers heatwave occurrences in April, May, June, and July, indicates that within India’s core heatwave zone, parts of western Rajasthan, Andhra Pradesh and Odisha were the worst affected between 1961 and 2020. Overall, 13% of the districts and 15% of the population are vulnerable to heat waves in India, the atlas showed. “There is a definite link between climate change and the rise in average temperatures, which is worsening the impact of heatwaves,” said Palawat. Human-induced climate change is already affecting many weather and climate extremes in every region across the globe, says the landmark Code Red report released in August 2021 by the Intergovernmental Panel on Climate Change. The report by the United Nations’ body of climate experts found that averaged over the next 20 years, global temperature is expected to reach or exceed 1.5 degrees Celsius of heating. The global average includes places like Antarctica and does not actually hold true all over India, where average temperatures have risen faster and higher. “Heatwaves and humid heat stress will be more intense and frequent during the 21st century,” the report said about South Asia, which includes India. This is validated by actual temperature records maintained by the Met Department and revealed in the study cited earlier.

Heat stress rising

It is now well established that extreme heat has a disproportionate impact on the poor and marginalised, of which there are a large number in India. Additionally, almost half of India’s working age population is engaged in farming, which requires long hours of outdoor heat exposure in summer. Add to that, the plight of construction workers, the second largest employer in the country, and the large number of people like rickshaw pullers whose work requires them to be outdoors when the heat is high, and it becomes clear that India faces a problem of gigantic proportions. While India’s average temperatures rose by more than 0.5 degrees between 1960 and 2009, the probability of a massive heat-related mortality event, defined as more than 100 deaths, shot up by as much as 146%, according to a 2017 study titled Increasing probability of mortality during Indian heat waves. “Our results suggest that even moderate and practically unavoidable increases in mean temperatures, such as 0.5 degree Celsius, may lead to large increases in heat-related mortality unless measures are taken to substantially improve the resilience of vulnerable populations,” the study had predicted. The years between 2010 and 2019 saw the highest emissions in human history (at 56 gigatonnes of carbon dioxide or its equivalent), and the window to adapt to and mitigate climate change is quickly narrowing, adds the latest IPCC report. In order to keep global temperatures to 1.5 degrees above pre-industrial levels, emissions would need to peak by 2025, and fall right after, with “rapid and deep” reductions following every decade till 2050. “Modelled mitigation strategies to achieve these reductions include transitioning from fossil fuels without Carbon Capture and Storage (CCS) to very low — or zero — carbon energy sources, such as renewables or fossil fuels with CCS, demand side measures and improving efficiency, reducing non-CO2 emissions, and deploying carbon dioxide removal (CDR) methods to counterbalance residual GHG emissions,” says the report. CCS refers to highly contentious technologies that can trap and store carbon dioxide from the atmosphere. These have been a point of division among climate activists and researchers, because they are not yet scalable, are expensive, and their ecological costs are still not fully known. Mitigation is of immediate concern in regard to high summer temperatures and subsequent heatwaves, says Palawat. “Both short term measures like advisories and long-term measures like afforestation have to be simultaneously acted upon,” he said.

Way forward

According to the report, relying on carbon capture and removal of “hard-to-abate residual emissions” is “unavoidable” if the world is to achieve its net-zero targets. The report adds that the efficiency, feasibility, and application of these technologies need to be studied further. Though the world is currently off-track to meet the 2015 Paris Agreement goal of keeping temperatures “well below” 2 degrees above pre-industrial level, the IPCC report presents several options for governments to avoid a world where temperatures soar to 3.2 degrees above it. For now, local governments may have to consider a range of measures to keep people safe from the heat. They could restrict school hours to the cooler morning hours of 7 am to 11 am, advise against farm and construction work in the afternoon and provide extra support to street vendors, outdoor workers, police and to those living in city slums without access to cooling devices. According to Koll from the Indian Institute of Tropical Meteorology, IPCC projections clearly show that the heat intensity is increasing and encroaching on our daily lives, and the impact is on vulnerable people who have little resources in regions where we don’t even have observations. We need higher resolution data and, more importantly, we need long-term policies.

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