Millennium Post
In Retrospect

Sweltering summers

Against the gravity that heatwave has acquired due to unprecedented rise in global temperatures, policy response in India, both in terms of adaptation and mitigation, has been lacklustre

Sweltering summers

So fond are the memories of the days when one eagerly waited for summer vacations, noon time was relished in gardens, with fellow kids gossiping about all that was under the sun. The heat was mostly bearable and at least the evening brought a good deal of respite, and even joy. At the crux of everything was an ambient moderation — something that humans are losing today. The clime today in India, and maybe in the rest of the world, is defined by extremity. The extremity, it seems, is getting harsher for summers. In fact, to quote the first part of the sixth IPCC report, "heat extremes have increased while cold extremes have decreased, and these trends will continue over the coming decades."

But certainly, extreme summers are not just about the lost joy of summer vacations. In the very recent past, it translated before our eyes in the form of countrywide power blackouts, raging fires in residential areas of Delhi and other cities and landfills that are still smouldering — serving as a persistent source of air pollution. It has been claiming human lives on a continuous basis, and is also robbing off, or at least affecting, the livelihoods of those who must venture out under the scorching sun, amid unbearable temperatures, to ensure their families don't sleep empty stomach at the end of the day. It has reduced their productivity, and hence curtailed their earnings. Additionally, the quantity and quality of food grains we consume are also downgrading — leading to food insecurity and nutrition deficiency.

It is true that high temperature and threatening loo have always been regular phenomena in Indian villages; Indian towns and cities too are used to sweltering summers. What has changed is the frequency — the world is witnessing extremities breached more often, and the increase of frequency is on an accelerating slope. Life and clime are visibly changing on the ground. In scientific lingo, the term 'heatwave' is circulating all around. In this article, we shall understand what exactly a heatwave is, why is it talk of the day, what are its socio-economic and health-related impacts, how is it interlinked with climate change and what is the way out of this conundrum?

What is a heatwave?

Heatwave is defined by the metrics of temperature relative to humidity. Absolute value of temperature fails to capture the essence of the heatwave phenomena. Apart from humidity, the ecological and topographical features too influence the heatwave. The World Meteorological Organization defines heatwaves as "five or more consecutive days during which the daily maximum temperature surpasses the average maximum temperature by five degrees Celsius (9°F) or more". In contrast, the Indian Meteorological Department defines heatwave as a situation when temperature reaches 40 degrees Celsius in the plains and at least 30 degrees Celsius in the hilly regions. Alternatively, the temperature increase should be in the range of 5-6 degrees Celsius above the normal temperature — which may vary for different regions. Depending upon their topographical features, different countries follow different definitions of heatwaves.

The variance of temperature threshold in different regional settings is somewhat easier to follow than the variance of temperature threshold for heatwave relative to humidity. Going by the IMD's definition of heatwave, it would occur when temperature crosses 40 degrees Celsius in the plains. But, in the same regional setting, a temperature of 30 degrees Celsius could prove lethal! Yes, if the humidity is as high as 90 per cent. Here comes in the concept of wet-bulb temperature which is a combined measure of heat and humidity. A wet bulb temperature in the range of 29 to 35 degrees Celsius could be very lethal. Certain weather-related national and international websites host calculators that can convert the relative figures of temperature and humidity into wet-bulb temperature.

In the past, a rise in temperature was usually accompanied by a fall in humidity. It means when the weather was too hot, our surroundings naturally gained an affinity to absorb the sweat perspiring from our skin surface. This cycle appears to be somewhat disturbed these days. Simultaneous rise in heat and humidity is becoming more common — and the heat remains contained inside the body as there is reduced scope for perspiration. To capture this emerging trend, wet-bulb temperature will have to be streamlined in the assessment of heatwaves.

Present status

To reiterate, India is no stranger to rough summers and extreme heatwaves but the intensity and frequency with which these are scaling up is alarmingly new. Usually, the last two summer months in the pre-monsoon cycle — April and May — witness high-intensity heatwaves. This year, oddly, March attained the notorious distinction of being the hottest month in the last 122 years since 1901 when the India Meteorological Department started collecting national records.

In April this year, Ganganagar in Rajasthan is reported to have crossed the 45 degrees Celsius-mark six times and Maharashtra's Chandrapur crossed 45 degrees Celsius a total of five times. These are just a few examples and demonstrate the level of gravity of the present heatwave crisis.

It goes without saying that heatwave phenomena are on the rise across the globe but South Asia has particularly grabbed the headlines this year.

Socio-economic and health-related impacts

Though the respective evolutions of nature and humans are intricately related with each other, for the sake of understanding, these can be de-clubbed in imagination for the time being. Human body, to exist and survive on the planet in the form it is, has adapted itself to the surroundings. Evolution, as we know, is a continuous process. However, owing to over-exploitation of natural resources, nature is forced to change more rapidly and drastically, and that too in an adverse manner, when compared to the evolution of the human body. This mismatch has been resulting in severe health impacts for the people.

The worst impact is excess mortality — meaning more people are dying due to heatwaves. As per a World Health Organisation (WHO) estimate, from 1998-2017, more than 1,66,000 people died due to heatwaves; and between 2000 and 2016, the number of people exposed to heatwaves increased by around 125 million — leading to greater chances of mortality.

Apart from excess mortality, serious morbidities also remain a cause of concern. Disproportionate exposure to heat causes exhaustion and heat stroke, skin swelling, lethargy, weakness, cramps, skin problems, dehydration, and cerebrovascular and cardiovascular attacks.

The health impact of heatwaves, however, is not so simplistic. It is relative to the geographical location of affected population, age and socio-economic profile of the people, their living conditions, access to cooling gadgets, nature of the work they do to earn their livelihood (outdoors or the indoors) etc. To map the real health impact of the heatwaves, localised study for various regions and diverse populations will have to be carried out.

Notably, socio-economic profiles of people play a decisive role in what manner, and to what extent, they will be impacted by heatwaves. The mitigation measures will also have to be formulated accordingly to ensure that the environmental crisis doesn't turn out to be a social crisis — exacerbating inequality in yet new forms.

Correlation with climate change

Obvious linkages between climate change and increased instances of heatwaves are being drawn by environment experts around the world.

A recent report by 30 scientists from 10 countries in the World Weather Attribution Network found that the unusual, early heatwaves sweeping India and Pakistan in 2022 were made 30 times more likely due to the direct impact of climate change. The rise in instances of heatwaves was attributed to a 1.2 degrees Celsius average global temperature rise over pre-industrial levels. The United Nations has also clearly enunciated that there is a direct link between the concentration of GHGs in the Earth's atmosphere and the average global temperature — rising GHG concentration has translated into increasing mean global temperature.

With the abysmal status of progress made on the climate conservation front, effective containment of global mean temperature appears to be far-fetched currently. Attainment of emission reduction and temperature threshold targets within specified deadlines also seems elusive. The failure on this front will naturally manifest into longer, more intense and frequent heatwaves. Council on Foreign Relations estimated that more than one-fifth of the global population now lives in regions that are already experiencing warming greater than 1.5 degrees Celsius — something that global environmental health bodies advocate should be avoided. In fact, regions like the Middle East may face four degrees Celsius warming by 2050 with the current rates of emission. CFR further stated that by 2050, more than 70 per cent of the global population could experience severe heatwaves. Notably, this year by April 29, 70 per cent of India was already affected by heatwaves.

The pace at which the planet is getting hotter is indeed alarming. The potential threats are horrifying — the present state of affairs is itself testing the limits of human survival. Columbia University's Earth Institute estimated that global warming can kill over 83 million people over the next eight decades. Urgent action is needed to save these lives, among other things.

The way forward

Going forward, the solution is already chalked out — it just requires an effective and hassle-free implementation. But the path to implementation presents the real challenge. The solution of the heatwave conundrum largely coincides with that of global warming and climate change. The well-established two-pronged approach including adaptation and mitigation has to be practiced in letter and spirit.

On the adaptation front, the global community must cut the ice on the issue of limiting global temperature below two degrees Celsius by the end of the century. The debate over who's contributed how much and who needs to do what to reduce carbon emissions has put the entire planet in a dangerous loop. The rigidity of both the developed and the developing world is doing no good to the world. A flexible approach, which incorporates the economic and geopolitical interests of both the blocks, will have to be worked out through diplomatic dialogue. The focus has to shift on the business side of tackling Climate Change sooner than later. Financial flows will have to be streamlined in terms of investment by the developed world — philanthropy and moral grounds are too feeble to serve as a base for transformative change in this direction. Climate change unequivocally torments the entire world and all the countries must stand united if a solution is to be found out.

On the mitigation front, the actions will have to be more localised. The first major challenge for India is to recognise heatwaves as a natural disaster. The country woke up to the problem only after the devastating heatwaves of 2010 — following which the National Disaster Management Authority pressed cities to formulate heat action plans (HAPs) in coordination with NGOs and civil society. Twelve years from then, the country is still struggling to implement effective HAPs. Heat action plans are basically aimed at community outreach and creating awareness among the masses, training health professionals and equipping them with the right resources to deal with affected persons and setting an early warning system in place.

Lessons can be learnt from France's National Heatwave Plan. The country's journey after it lost 15,000 lives to a devastating heatwave in 2003, has been exemplary. It has cut 90 per cent of the death toll and boasts of a well-oiled awareness machinery.

In addition, efforts should be made to enhance access to air conditioning. As per International Energy Agency, less than one-third of global households have access to air conditioning. This is in fact a very tricky situation. While improving access, the overwhelming pressure on power systems will also have to be balanced.

Infrastructure also needs to be upgraded. Urban construction has become obsolete against the rapidly changing climate. Restructuring these is the need of the hour.

Views expressed are personal

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