TOPIC: THE WORLD HAS NO CHOICE BUT TO CARE ABOUT INDIA’S HEAT WAVE

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THE CONTEXT: It has been emphasised over and over again – climate change is not a phenomenon of the future. It is the phenomenon of now. Several parts of the country are experiencing record temperatures after long periods of winter, with heatwaves forecast in numerous states. According to the Indian meteorological department (IMD) began keeping statistics, the month of March this year (2022) was the hottest in 122 years. The rainfall deficit in India was as high as 72 per cent, with the deficit reaching 89 per cent in the country’s northwest.

In this article, we analyse what is a Heatwave? IMD Criteria for Heatwave, its impacts and its way forward.

THE BASICS

What is a heatwave?

• A Heat Wave 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.
• Heat Waves 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.

THE INDIAN METEOROLOGICAL DEPARTMENT (IMD) HAS GIVEN THE FOLLOWING CRITERIA FOR HEAT WAVES:

• Heat Waves 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.

 Based on Maximum Temperature Department from Normal

• Heatwave: Departure between 4.5° C to 6.4°C
• Severe Heatwave: Departure >6.4°C

Based on Maximum Temperature

• Heatwave: Temperature ≥ 45°C
• Severe Heatwave: Max. Temperature ≥47°C

Warm Night:

Considered when Maximum Temperature ≥40°C and departures of Minimum Temperature from normal are as follows:

• Warm Night: Departure between 4.5°C to 6.4°C
• Very warm Night: Departure ≥6.4°C

CLIMATOLOGY OF HEATWAVES

• The high temperatures start building over central India in April and spread northwards during May. Due to the southwest monsoon onset during June, high temperatures are mostly seen over northwest India.
• The month of May experiences the maximum number of heat wave days along with maximum spatial coverage.
• Maximum heat wave events during the summer season are seen over the northwest and plains of north India and also over eastern and central India.
• The number of heatwave days ranges from 1-to 2 weeks and severe heat-wave days up to 1 week over the heat core zone of the country.

Favourable conditions of Heat Waves

• A heat wave is formed due to static high pressure in the upper atmosphere.
• This generates a hot mass of air and traps more heat due to a reduction in convection currents.
• This air mass accumulated heat and humidity causing abnormally high temperatures.

Human-Led Ecological Changes: The climate change impacts have also become more pronounced due to the fast ecological changes, including deforestation, which has rendered vast areas of land exposed to direct sunlight that was earlier protected by a green cover.

“Large-scale deforestation along the foothills of Himalayas for development purposes has disrupted the ecological balance and contributed to warmer conditions in those places. The situation in cities has worsened due to more dependency on air conditioners and the urban heat island effect which has increased temperatures.

Other Factors for heat waves are:

• Transportation/ Prevalence of hot dry air over a region.
• Absence of moisture in the upper atmosphere.
• The sky should be practically cloudless.
• Large amplitude anti-cyclonic flow over the area.
• Lack of pre-monsoon showers: Except for the southern peninsula and northeast regions, the weather has remained dry across the rest of the country. Once, in the last week, parts of Jammu and Kashmir and Delhi reported light to moderate rainfall. The lack of pre-monsoon showers has also led to an increase in the overall maximum temperature. Maharashtra recorded 63 per cent deficient rainfall from March 1 to April 26. (2022)

HOW INDIA METEOROLOGICAL DEPARTMENT (IMD) MONITORS THE HEATWAVE?

IMD has a big network of surface observatories covering the entire country to measure various metrological parameters like Temperature, Relative humidity, pressure, wind speed & direction etc. Based on daily maximum temperature station data, climatology of maximum temperature is prepared for the period 1981-2010 to find out the normal maximum temperature of the day for a particular station. Thereafter, IMD declared heat waves over the region as per its definition.

IMPACT OF HEATWAVES

What is the Impact of these Heat Waves?

Mortality and Morbidity: The Intergovernmental Panel on Climate Change (IPCC) in the Second Part of the AR6 Report flagged that heat extremes are causing human deaths and morbidity.

The increased heat will lead to an increase in diseases like diabetes, circulatory and respiratory conditions, as well as mental health challenges.

• Accelerating Global Warming: According to the former IMD DG who led India’s weather department from 2016 to 2019, heatwaves are likely to get stronger with the rapid thinning of the Arctic Sea ice, which is now at its all-time low due to global warming.
• Will Fuel More Thunderstorms: Intense heating of the land will also fuel more thunderstorms, which is yet another weather extreme that continues to claim hundreds of lives every year. “As temperatures increase, and there are more heatwaves, these long spells will be broken by thunderstorms or dust-storms, which will also get intense and stronger.

STRATEGY TO DEAL WITH HEATWAVES

• In 2016, the NDMA drew up the first national guidelines for heatwaves titled ‘Preparation of Action Plan–Prevention and Management of Heat Wave’.
• The National Guidelines on Heat Wave mentions the roles and responsibilities of the central and state government agencies, district administrations, local self-governments, NGOs, civil society organisations and other stakeholders in a matrix format.

Heat Action Plan

Since 2013, the India Meteorological Department (IMD), in collaboration with local health departments, has started issuing heat action plans in many parts of the country to forewarn about heatwaves as well as advise action to be taken during such occasions.

India Meteorological Department issues the following colour code impact-based heat warning jointly with National Disaster Management Authority:

IMD issued an Orange alert for Rajasthan, Madhya Pradesh, and Maharashtra’s Vidarbha area. For weather alerts, the IMD employs four different colour codes. Green indicates that no action is required, yellow indicates that you should watch and stay informed, orange indicates that you should be prepared, and red indicates that you should take action. Temperatures in portions of northwest India could reach 47 degrees Celsius, according to forecasters.

THE WAY FORWARD:

Adopting A More Sensitive Approach: The impact of such excessive heat needs to be understood from the point of view of common people — daily labourers; farmers; traders; fishermen etc.

• Beyond numbers and graphs that capture the impact of the climate crisis, the human experience of living in oppressive heat needs to be understood by policymakers and measures should be taken accordingly.

Cooling Shelters: The government should come out with a policy to deal with the suffering and disability caused by heat extremes in different parts of the country.

• Water kiosks, staggered outdoor work hours, and cool roofs for buildings and homes are certain things that should be put in place immediately.

Passive Cooling to Reduce Urban Heat Islands: Passive cooling technology, a widely-used strategy to create naturally ventilated buildings, can be a vital alternative to address the urban heat island for residential and commercial buildings.

• The IPCC report cites ancient Indian building designs that have used this technology, which could be adapted to modern facilities in the context of global warming.

Action Plans Similar to Ahmedabad: As per the IPCC Report, Ahmedabad has shown a way to combat heat extremes by heat-proofing buildings.

• After the heat action plan was implemented in 2013 in Ahmedabad, heat-related mortality was reduced by 30% to 40% over the years. Similar plans like that of Ahmedabad can be implemented in vulnerable regions.

THE CONCLUSION:Increased exposure to heatwaves needs a policy response, nationally and globally. Long-term measures should be taken to address the issue in the wake of global warming and climate change. Afforestation drives to increase green cover. A further reduction in the share of coal in the energy mix through sustained support for renewable energy, particularly solar photovoltaic, must form the cornerstone of national policy.

 ADD TO YOUR KNOWLEDGE

During the intense heatwave in Delhi, when the mercury surpassed 35 degrees Celsius even at night, discussions on the growing number of urban heat islands in the Capital have once again come to the fore. According to experts,“The combination of high day and night-time temperatures is dangerous as it seriously impacts the blood circulation and other bodily functions of people, especially the elderly”.

As the house becomes hot and is unable to cool down by midnight, it starts acting as a heat trap. In such a situation, the body gets heated overall and the heart starts pumping more blood to fight dehydration if adequate water intake is not maintained. If one’s heart is already weak, it may fail and the person may die due to cardiac failure induced due to heatwaves.”

Heat-related deaths: Data on ‘Accidental Deaths & Suicides in India’ released by the National Crime Records Bureau show over the years heatstrokes have become the second leading cause of death from a natural force in India, with 11,555 people being killed in 2011 to 2020 due to the condition.

Growing heat island effect: An image captured by NASA on May 5, 2022 showed how night-time temperatures in Delhi and adjoining villages were above 35 degrees Celsius, peaking at about 39 degrees Celsius, while the rural fields nearby had cooled to around 15 degrees Celsius by then.

The World Weather Attribution network, which analysed the heat patterns in India from March-April, found that the probability of long-duration heatwaves had increased by 30 times due to human-induced climate changes.

Mitigative approach: One way of countering the growing impact of urban heat islands is ‘green infrastructure’ that includes cool roofs or painting house roofs in a light colour to reflect heat and using sustainable cooling mechanisms. Promoting urban forestry and green transport can also help cut down heat emissions.

QUESTIONS TO PONDER:

1. What are heat waves? What are the favourable conditions for Heat waves and Suggest measures to create a buffer against high temperatures?
2. What are Urban Heat Islands? Discuss its causes and impacts in the context of the urban landscape.
3. What are the criteria for declaring Heat waves in India? Discuss the different colour codes employed by IMD for heatwave warning.