UPSC Issue at a Glance | Heatwaves: 5 Key Questions You Must Know for Prelims and Mains

🚨 The Indian Express UPSC Essentials brings to you the May edition of its monthly magazine. Click Here to read. Share your views and suggestions in the comment box or at manas.srivastava@indianexpress.com🚨

What is the issue?

Higher daily peak temperatures and longer, intense heatwaves are becoming increasingly frequent globally. India is also feeling the impact of increased instances of heatwaves which have a devastating effect on human health and the environment. Therefore, let us understand the issue of heatwaves from a broader perspective.

UPSC Syllabus: 

Preliminary Examination: General issues on Environmental Ecology, and Climate Change – that do not require subject specialisation.

Mains: GS-I, GS-II, GS-III: Important Geophysical Phenomena, Climate Change Environmental Pollution & Degradation, Government Policies & Interventions.

Other areas of relevance: UPSC Aspirants will find it useful in Essays, and Current affairs for their Personality tests.

Question 1: What are heatwaves and the criteria for declaring them?

Answer: According to the Indian Meteorological Department (IMD)- 

A heatwave is a period of abnormally high temperatures, more than the normal maximum temperature that occurs during the summer season in the North-Western parts of India. Heatwaves typically occur between March and June, and in some rare cases even extend till July. The extreme temperatures and resultant atmospheric conditions adversely affect people living in these regions as they cause physiological stress, sometimes resulting in death.

IMD Criteria for Declaring Heatwaves in India

—  A heatwave is declared when the maximum temperature of a station reaches at least 40°C or more for plains, 37°C or more for coastal stations, and at least 30°C or more for hilly regions.

— Based on departure from normal temperatures, the following criteria are used to declare a heatwave:

(i) Heatwave: Departure from normal is 4.5°C to 6.4°C.

(ii) Severe Heatwave: Departure from normal is 6.4°C.

Learn through image: Criteria for Declaring Heatwaves in India.

— Based on the actual maximum temperature in plains, the following criteria is considered:

(i) Heatwave: When the actual maximum temperature ≥ 45°C

(ii) Severe Heatwave: When actual maximum temperature ≥47°C

— If the above criteria met at least in 2 stations in a Meteorological sub-division for at least two

consecutive days and it was declared on the second day.

Points to Ponder: 

— What is the difference between a heatwave and a warm spell?

— What is a warm night?

— Why is humidity an important aspect when measuring heat exposure?

— Is there any universal numeric limit to characterise heatwaves?

Post Read Question:

Prelims

(1) Consider the following statements:

1. Heatwaves typically occur between March and June, and in some rare cases even extend till July.

2. Heatwaves need not be considered till the maximum temperature of a station reaches at least 40°C for Plains and at least 30°C for Hilly regions.

3. A severe heatwave is declared when the departure from normal is more than 6.4 degrees Celsius.

How many of the statements given above is/are correct?

(a) Only 1

(b) Only 2

(c) All three

(d) None

Mains

In recent years, studies have underlined the need to fine-tune the maximum temperature-based criteria to declare a heatwave. Why do we need to act now?

(Source: Heat index highest in parts of Southwest Delhi, lowest in New Delhi , UPSC Key— 11th April, 2024, heatwave,.imd.gov.in,UPSC Key— 3rd April, 2024: Kallakkadal, India’s new geopolitics, Heatwaves and more )

Question 2: What causes heatwaves? 

Answer: Heatwave conditions are regionally defined and can vary substantially at sub-national scales due to influences from geography, topography, atmosphere, and other conditions. Here are some causes that are driving the frequent heatwaves.

1. Climate Change: Climate change is causing a rise in global temperatures. As the planet heats up, it leads to more extreme weather events, such as heatwaves.

2. El Niño: According to Mrutyunjay Mohapatra, director general of the IMD, the years that begin in an El Niño state, experience extreme temperatures, harsh, multiple and extended heatwave spells, and lack of pre-monsoon rainfall.

— El Nino conditions are exacerbating the extreme heat around the world. Essentially a weather pattern that refers to an abnormal warming of surface waters in the equatorial Pacific Ocean, El Nino is known to “greatly increase the likelihood of breaking temperature records and triggering more extreme heat in many parts of the world and in the ocean,” a World Meteorological Organisation (WMO) report said.

3. Heat Dome: A heat dome, occurs when an area of high-pressure stays over a region for days and weeks. It traps warm air, just like a lid on a pot, for an extended period. The longer that air remains trapped, the more the sun works to heat the air, producing warmer conditions with every passing day. Heat domes, if they last for a long period, may cause deadly heatwaves.

4. Anticyclone: An anticyclone, also known as a high-pressure system, is essentially an area of high pressure in which the air goes downwards towards the Earth’s surface. As the air sinks, its molecules get compressed, which increases the pressure, making it warmer. This causes dry and hot weather. The winds remain calm and gentle during an anticyclone, and there is almost no formation of clouds because here the air sinks rather than rises.

Points to Ponder: 

— What are El Nino and La Nina?

— What do you understand by the term “urban heat island effect”?

Post Read Question:

Bring out the causes for the formation of heat islands in the urban habitat of the world. (UPSC CSE 2013)

(Source: Explained Climate: Heatwaves and climate change, El Nino, anti-cyclone systems: Why large parts of India experienced heatwaves in April, Heat domes, anticyclones and climate change: What’s causing heatwaves across the world? )

Question 3: What are heatwave conditions in India?

Answer: This year, April has been abnormally hot. According to the IMD, heatwave conditions occurred in either a small pocket or a very large geographical area of India during the first 26 days of April, and it is expected that in the coming months the events of heatwaves will be more frequent.

According to WHO– In India Heatwaves typically occur from March to June, and in some rare cases, even extend till July. On average, five-six heatwave events happen every year over the northern parts of the country. Single events can last weeks, occur consecutively, and can impact a large population. 

Favorable Conditions for Heatwaves

According to IMD the favorable conditions for Heatwaves are: 

(i) Transportation / Prevalence of hot dry air over a region (There should be a region of warm dry air and appropriate flow pattern for transporting hot air over the region).

(ii) Absence of moisture in the upper atmosphere (As the presence of moisture restricts the temperature rise).

(iii) The sky should be practically cloudless (To allow maximum insulation over the region).

(iv) Large amplitude anti-cyclonic flow over the area.

Areas in India Prone to Heatwaves

— The Core Heatwave Zone (CHZ) spanning central, north, and peninsular India between Gujarat and West Bengal is prone to heatwave conditions every year, during the summer season March to June and occasionally in July.

— Rajasthan, Punjab, Haryana, Chandigarh, Delhi, West Madhya Pradesh, Uttar Pradesh, Chhattisgarh, Odisha, Vidarbha in Maharashtra, parts of Gangetic West Bengal, coastal Andhra Pradesh, and Telangana are the most heatwave-prone states or regions.

Learn through image: IMD issues following colour code impact-based heat warning jointly with National Disaster Management Authority. (Source: IMD)

Points to Ponder: 

— What is the core heatwave zone?

— Is a heatwave recognised as a natural disaster in India?

Post Read Question:

Prelims

(2) Which of the following is/are the favorable conditions for Heatwave?

1. Prevalence of hot dry air over a region

2. Absence of moisture in the upper atmosphere

3. Cloudless sky

4. Large amplitude anti-cyclonic flow over the area.

Select the correct answer using the codes given below:

(a) 1, 2 and 3 only

(b) 2, 3 and 4 only

(c) 1,2 and 4 only

(d) 1,2,3 and 4

Mains

What criteria have been used by IMD to declare heatwaves? What steps can be taken by the government to control the adverse effects of the heatwave?

(Source: Heatwaves in several parts of India: Why has April been hotter than usual? Express View on IMD’s heatwave alert: Act Now, What is a citizen’s ‘right to be free from the adverse effects of climate change’, .imd.gov.in)

Question 4: What are the impacts of heatwaves?

Answer: Heatwaves are among the most dangerous natural weather hazards. Intense heatwaves can have serious environmental, health, social, and economic consequences. 

According to World Meteorological Organization (WMO)-

Heatwaves amplify many risks, such as health-related or economic risks, including increased human mortality, drought and water quality, wildfire and smoke, power shortages and agricultural losses.

According to IMD- 

“Heatwaves affect human health and air quality, increase energy consumption, reduce crop yields, increase water loss and intensify droughts….. Heatwaves also increase temperatures in buildings and cities (urban heat islands), cause disruptions in critical infrastructure networks, affect the economy through lower labour productivity, and exacerbate the impacts of other climate-related hazards such as droughts or forest fires.”

1. Impact on Environment: According to WMO- “Multiple risks interact with heatwaves such as droughts, fire weather, flash flooding and air pollution which have compounding impacts for people and nature. Hot extremes including heatwaves have intensified in cities, where they have also worsened air pollution events and limited functioning of key infrastructure.”  It can also increase the risk of wildfires.

2. Impact on Health: Anjal Prakash writes- “The impact of heatwaves on human health is significant. Heat-related illnesses, such as heat exhaustion and heatstroke, are becoming more common, particularly among vulnerable groups such as the elderly, children, and outdoor workers. In addition, heatwaves can exacerbate existing health problems, such as respiratory and cardiovascular diseases.”

According to IMD- 

Heatwaves have claimed more lives in India than other natural hazards, with the exception of tropical cyclones.

K Srinath Reddy writes- “A study of 266 studies worldwide, published in 2022, revealed that heatwaves were associated with a 11.7 per cent increase in mortality. The highest specific risk was for stroke and coronary heart disease. A high risk was also reported for fatal and non-fatal cardiac arrhythmias.”

— Heatwaves can also create ideal conditions for pests and insects to thrive. This can lead to increased damage to crops and the need for more pesticides, which can be costly for farmers. High temperatures can lead to increased evaporation of water from soil, reducing soil moisture levels and making it more difficult for crops to grow.

4. Impact on Livestock Health: Heat stress can be a major issue for livestock, resulting in lower milk production, lower fertility rates, and even death in severe circumstances.

5. Water Scarcity: Heatwaves can exacerbate existing water scarcity issues by causing water sources to dry up faster and increasing demand for irrigation.

6. Impact on the Energy Sector: Heatwaves can have significant impacts on the energy sector, causing grid stability issues, increased expenses, and power outages. Heatwaves can lead to increased demand for electricity, transmission and distribution issues, and reduced power generation due to inefficient power plants, particularly those that rely on water for cooling.

Points to Ponder: 

— What are some heat-related illnesses (HRIs)?

— How heatwaves are affecting labour productivity?

— What are the impacts of heatwaves on developed and developing countries?

— Discuss the impact of heatwaves on food security and human health. 

(Thought Process: Mention the nexus of the heatwave, health, and food security–cite data from WMO and ILO–need for international collaboration in climate resilient agriculture to ensure food security–recognizing heatwave as ‘natural disaster’-adoptive measures from individual level to international level.)

Post Read Question:

Prelims

(3) Consider the following:

1. Heat stroke

2. Heat cramps

3. Heat fatigue

What are not the health effects of heatwaves?

(a) Only one

(b) Only two 

(c) All three

(d) None

Mains

In theory, all or most heat-related deaths and illnesses are preventable while in practice, gauging the public health impact of extreme temperatures is difficult. So, in a heatwave, how do we protect our most vulnerable?

(Source: A climate scientist writes: With record-breaking heatwaves, India is sizzling. It is time to act, Heatwaves, Chapter 8 Impacts and adaptation – IMD, )

Question 5: What measures should be taken to mitigate the impacts of heatwaves? 

Answer: The increased frequency of heatwaves is a severe concern that must be addressed urgently. Heatwaves have a substantial environmental, health, and economic impact. However, with the appropriate strategies in place, it is possible to mitigate the impacts of heatwaves and ensure a sustainable future for the country. The following measures can be taken to mitigate the impacts of heatwaves:

1. Comprehensive Response Plan: The effective way to mitigate the negative impacts of a heatwave is to develop a comprehensive response plan that integrates individual initiatives, institutional technology, and ecosystem-based responses.

2.Improving the Built Environment: We need to improve the built environment to make it more heat-resistant. This can be done by increasing the green cover in cities and improving building insulation and ventilation systems. Implementing these strategies can lessen the urban heat island effect, which occurs when cities are significantly hotter than surrounding areas.

Some measures suggested by Anjal Prakash are-

3. Increase Public Awareness: People need to be educated about the impact of rising temperatures on their health, the environment, and the economy. This can be done through public campaigns, schools, and the media.

4. Increase the use of Renewable Energy: India has already made significant progress in this area. The country registered the highest year-on-year growth in renewable energy, of nearly 10 per cent, in 2022. However, much remains to be done. The government could incentivise individuals and businesses to invest in renewable energy, such as solar panels. This would help reduce the impact of rising temperatures, create new jobs, and stimulate economic growth.

5. Investment in Infrastructure: Investing in infrastructure that can cope with extreme temperatures is essential. This could include the construction of roads and buildings that are designed to withstand high temperatures, as well as the development of more efficient cooling systems that use less energy.

Points to Ponder: 

— What are the initiatives taken on the international level to mitigate the impact of heatwaves?

— What is the Sendai Framework for Disaster Risk Reduction 2015-30?

— How is India adapting to heatwaves?

— Organisations to look for: WMO, WHO, IMD, NDMA.

Post Read Question:

Climate change’ is a global problem. How India will be affected by climate change? How Himalayan and coastal states of India will be affected by climate change? (UPSC CSE 2017)

(Source: Chapter 8 Impacts and adaptation – IMD, A climate scientist writes: With record-breaking heatwaves, India is sizzling. It is time to act, Express View on IMD’s heatwave alert: Act Now,)

Edited by Manas Srivastava

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