QUES . “Heat waves are expected to become longer and more intense and frequent over the Indian subcontinent.” Examine the statement. UPSC IES/ISS EXAM 2023 General Studies . 200 Words . 5 Marks
HINTS:

Severe heat waves, responsible for thousands of deaths across India over the last few decades, are increasing with alarming frequency and soon the country could become one of the first places in the world to experience heat waves that break the human survivability limit, according to a new report.
Deadly heat waves fueled by climate change are threatening India’s development and risk reversing its progress on poverty alleviation, health and economic growth.
Heat waves have already critically impacted the country, leading to power outages, increased dust and air pollution, and accelerated glacial melt in the north of India.
Facts related with heat waves over the Indian subcontinent
In August 2021, the Sixth Assessment Report of the Inter-governmental Panel on Climate Change (IPCC) warned that the Indian subcontinent would suffer more frequent and intense heat waves over the coming decade.
The G20 Climate Risk Atlas also warned in 2021 that heat waves across India were likely to last 25 times longer by 2036-65 if carbon emissions remain high.
Since 1992, more than 24,000 people have died because of heat waves in India. And the impacts are expected to get worse as heat waves become more frequent, intense and lethal due to the climate crisis.
Long-term projections indicate that Indian heat waves could cross the survivability limit for a healthy human resting in the shade by 2050.
In 2022, India experienced its hottest April in 122 years and its hottest March on record. And it experienced extreme weather on 242 out of 273 days between January and October 2022.
How do heat waves occur?
Heat waves are formed for one of the following reasons:
1 . Warmer air is flowing in from elsewhere.
2 . Warmer air is being produced locally.
3 . Air masses
1 . Warmer air is flowing in from elsewhere
In spring, India typically has air flowing in from the west- northwest. In the context of climate change, West Asia is warming faster than other regions in latitudes similarly close to the equator, and serves as a source of the warm air that blows into India.
Likewise, air flowing in from the northwest rolls in over the mountains of Afghanistan and Pakistan, so some of the compression also happens on the leeward side of these mountains, entering India with a bristling warmth.
While air flowing over the oceans is expected to bring cooler air, the Arabian Sea is unfortunately warming faster than most other ocean regions.
The strong upper atmospheric westerly winds, that come in from the Atlantic Ocean over to India during spring, control the near surface winds.
When winds blow from west to east, they move faster than the planet’s rotation, which creates energy that can only come from above. This energy causes descending air to compress and warm up, which can generate heat waves.
2 . Warmer air is being produced locally.
It is a local phenomenon when the air is warmed by higher land surface temperature or because the air sinking down from above is compressed along the way, producing hot air near the surface.
Global warming is causing the lapse rate to decline, meaning that the upper atmosphere is warming faster than the air near the surface. As a result, sinking air is warmer due to global warming, which causes it to produce heat waves as it sinks and compresses.
3 . Air mass
The north- northwestern heatwaves are typically formed with air masses that come from 800 – 1600 km away and are around two days old.
Heat waves over peninsular India on the other hand arrive from the oceans, which are closer (around 200 – 400 km) and are barely a day old. As a result, they are on average less intense.
Why heat waves are expected to become longer and more intense and frequent over the Indian subcontinent?
In spring, India typically has air flowing in from the west- northwest. In the context of climate change, West Asia is warming faster than other regions in latitudes similarly close to the equator, and serves as a source of the warm air that blows into India.
While air flowing over the oceans is expected to bring cooler air, the Arabian Sea is unfortunately warming faster than most other ocean regions.
Global warming is causing the lapse rate to decline, meaning that the upper atmosphere is warming faster than the air near the surface. As a result, sinking air is warmer due to global warming, which causes it to produce heat waves as it sinks and compresses.
India has demonstrated tremendous leadership in scaling up heat action plans in the last five years by declaring heat waves a natural disaster and mobilizing appropriate relief resources. But as the heat waves in India and the Indian subcontinent become recurrent and long-lasting, it is high time that climate experts and policymakers reevaluate the metrics for assessing the country’s climate vulnerability.