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Climate change is making heatwaves long & deadlier, but there is no mitigation effort

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Climate change is making heatwaves long & deadlier, but there is no mitigation effort

A heat wave is an extended period of excessively hot weather that can have serious consequences for human health and the environment...

Climate change is making heatwaves long & deadlier, but there is no mitigation effort

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A heat wave is an extended period of excessively hot weather that can have serious consequences for human health and the environment. Heatwaves are expected to increase with climate change, posing a significant threat to population health. In India, with the world’s largest population, heatwaves occur annually but have not been comprehensively studied. India has had several heatwaves which have increased in frequency during the last decades. Most notably, in May 1998, India experienced a severe heatwave over 2 weeks considered to be the worst in the preceding 50 years. However, the worst was saved for 2023-24! Scientists had already predicted the incoming heatwave in India, largely due to the El Niño effect. El Niño alters global weather patterns by shifting warm water to the eastern Pacific, heating the air and causing hotter weather worldwide. The current cycle which began in 2023 and is expected to last until June 2024, potentially making this summer extremely hot. Official data shows that 2023 was hotter than previous years.

What are heat waves

A heat wave is an extended period of excessively hot weather that can have serious consequences for human health and the environment. In a heat wave, temperatures rise significantly above the average for a particular region and time of year. Heat waves can cause exhaustion, stroke, and even death in extreme cases. A heat wave is not just high temperature, it is defined by unusual temperature increases. For instance, a location that typically experiences 40 degrees Celsius in summer is not considered to be having a heat wave even if the temperature rises to 42 or 43 degrees. Conversely, a place where the normal temperature is 27 or 28 degrees would be experiencing a heat wave if the temperature reaches 35 degrees. According to the India Meteorological Department (IMD), a heat wave is considered if the maximum temperature of a station reaches at least 40 degrees Celsius or more for Plains and at least 30 degrees Celsius or more for Hilly regions. However, it also notes the temperatures at which heat waves are declared differ from place to place based on the temperature climatology of the region.

Increasing frequency of heat waves

Heat waves have become increasingly frequent in India due to climate change. The heat wave in North India, with temperatures nearing 50 degrees Celsius in some areas, is a recent example. The IMD had issued a red alert for several states, including Delhi, Haryana, Punjab, Uttar Pradesh, Rajasthan, Madhya Pradesh, and Gujarat. Certain regions in India are more susceptible to heat waves due to their location and climate. The northwestern and central parts of the country, including Rajasthan, Madhya Pradesh, and Gujarat, are prone to heat waves due to their continental climate characterised by hot, dry summers and sparse rainfall. This year, a heat wave has triggered a severe water and power crisis in several areas of the Jammu division, prompting the authorities to set up control rooms and appoint nodal officers in each district to cater to public complaints. Jammu has been reeling under extreme heat for the past fortnight.

How do heatwaves form in India?

A series of atmospheric and oceanic events triggers heatwaves over north-central and eastern India. Persistent hot and dry conditions in the wheat-growing north-central region, like the 2015 event that claimed over 2,500 lives are linked to stationary high-pressure systems. These systems disrupt normal weather patterns by blocking usual flows and allowing slow-moving Rossby waves to transfer heat. El Niño, which raises ocean temperatures, along with a high-pressure system blocking moist sea breezes from the Bay of Bengal and the Arabian Sea, led to record-high April temperatures in many parts of India this year. Even Kerala, a coastal state in the southwest where heatwaves are rare, was affected.

Why is the heat increasing in India

The IMD reported that a combination of weather patterns is causing temperatures to rise in the breadbasket region. While summer temperatures in India typically peak in May, the IMD has forecasted 7-10 heat wave days in the northwestern regions this month, compared to the usual 2-3 days. This increase is mainly attributed to fewer non-monsoon thunderstorms and an active but weakening El Nino, a climate pattern that usually brings hot and dry weather to Asia and heavier rains to parts of the Americas. Additionally, warm westerly winds from Pakistan are contributing to the heat. Elsewhere in India, summer temperatures have already reached record highs, particularly in the eastern and southern regions, where April temperatures were among the highest on record.

What are Rossby waves?

Think about the atmosphere as a large, moving fluid. Just like water in the ocean, the air in the atmosphere moves in waves. The Earth is spinning and this rotation affects how air moves around the planet. The rotation causes the Coriolis effect, which influences the direction of winds and ocean currents. Rossby waves are large waves in the atmosphere that form because of the Earth's rotation. They are named after Carl-Gustaf Rossby, who first identified them, according to NASA. These waves play a crucial role in our weather. When a Rossby wave moves, it can change the position of high and low-pressure systems, bringing different weather conditions to various parts of the world. For example, it might cause cold air to move south or warm air to move north.

The urban effect

A study by the Centre for Science and Environment identifies the "urban heat island" effect as a key factor in rising temperatures. This phenomenon occurs when densely built areas trap heat, reduce green spaces, create congestion, and absorb and generate additional heat through human activities. Climate researchers say that heat waves occur when there is high pressure in the atmosphere that forces hot air downward and traps it near the ground. This high-pressure system acts like a lock that prevents the hot air from rising, causing the temperature to rise further. The air compresses and heats up as it sinks, leading to extreme heat conditions. Additionally, climate change contributes to more frequent and intense heat waves by altering global weather patterns and increasing the likelihood of prolonged periods of high pressure.

Effect on the human body

Intense heat and humidity disrupt the body's ability to cool itself, leading to illness and potentially fatal outcomes even at lower temperatures. This dangerous combination is driving up the heat index, a metric that gauges how uncomfortable the weather feels

World bank report

A World Bank report predicts that by 2030, heat stress could lead to a global loss of 80 million jobs due to decreased productivity, with India potentially bearing 34 million of these job losses. A team of researchers, including those from the University of Nevada studied 53 million births across the 50 largest metropolitan areas in the US over 25 years (1993-2017). They analyzed daily counts of preterm and early-term births and found that preterm births increased by 2 percent, and early-term births increased by 1 percent following a four-day period during which each day's average temperature was among the hottest 2.5 percent for that region. “Each 1 degree Celsius increase in mean temperature above the threshold was associated with a 1 per cent increase in the rate of both preterm and early-term birth,” the authors wrote in the study published in The Journal of American Medical Association (JAMA) Network Open. Apart from that, heat waves are also known to worsen respiratory conditions and lead to breathing difficulties, particularly in areas with poor air quality. High temperatures can also strain the heart and circulatory system, increasing the risk of heart attacks and other cardiovascular issues

Economic implications of high temperatures

As temperatures rise, concerns about the economic impact of heat waves are growing. The negative effects are not limited to human suffering but also affect a wide range of economic activities. Heat waves often result in decreased workforce productivity. High nighttime temperatures make it difficult for the body to cool down, especially in urban areas experiencing the urban heat island effect, where temperatures are significantly higher than in surrounding regions. This phenomenon worsens the impact of heat waves. In a country like India, where a large portion of the workforce is engaged in outdoor activities, the consequences are severe. Around 45.76 percent of the workforce is employed in agriculture, with 83 percent working in the unorganized sector. Outdoor workers, including farmers, are particularly vulnerable to heat-related illnesses such as heat exhaustion and heat stroke, leading to frequent breaks and reduced productivity. A study by Cambridge University last year warned that extreme heat could reduce outdoor working capacity by 15 percent, potentially lowering the quality of life for millions and causing a 2.8 percent decline in India’s GDP by 2050.

What is Nautapa

Nautapa are the nine days when heat is at its worst in India. It is also known as ‘Navtaap’. The term Nautapa translates to ‘nine hot’ (nau = nine, tapa = heat). These days are also the hottest of the year. In 2024, Nautapa began on May 25 and continued until June 2. During Nautapa, the sun is directly over Central India, minimising the distance between the Earth and the sun. This results in more direct and intense solar radiation, causing severe heat. Temperatures are expected to reach close to 50°C in some areas, particularly in Rajasthan, Haryana, Punjab, Madhya Pradesh, and Gujarat.

How to protect yourself in the sweltering heat

To protect yourself during this period of extreme heat, doctors have recommended that it is essential to stay hydrated, consume a liquid-rich diet, avoid outdoor activities, wear protective clothing, and seek medical attention if you experience any health issues.

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