Heat waves can be studied both from the point of Environment and Geography.
The Geographical aspects of it are related to the Geo-physical phenomenon involved in heat waves and the Environmental aspects are related to impact of Climate change on heat waves. The best way for preparing holistically for the topic is to study at 4 levels :
- Geographical aspects
- Environmental aspects
- Governance and administrative measures to mitigate their impact
- Various impacts of heat waves, specifically Economic Impact
Heat waves impact on India
Placing in the syllabus
Geophysical events and climate change
- What is heat wave?
- Causes of heat waves?
- Climate change and heat waves
- Impact on India
- Heat waves and NDMA guidelines
What is a heat wave?
A heat wave can be seen as “an extended period of unusually high atmosphere-related heat stress”. Therefore, a heat wave always includes the combination of intensity and duration of high temperature periods.
The Indian Meteorological Department (IMD) has given the following criteria for Heat Waves:
- Heat Wave need not be considered till maximum temperature of a station reaches at least 40˚C for Plains and at least 30˚C for Hilly regions.
- When normal maximum temperature of a station is less than or equal to 40˚C Heat Wave Departure from normal is 5˚C to 6˚C Severe Heat Wave Departure from normal is 7˚C or more.
- When normal maximum temperature of a station is more than 40˚C Heat Wave Departure from normal is 4˚C to 5˚C Severe Heat Wave Departure from normal is 6˚C or more.
- When actual maximum temperature remains 45˚C or more irrespective of normal maximum temperature, heat waves should be declared.
Higher daily peak temperatures and longer, more intense heat waves are becomingly increasingly frequent globally due to climate change. India too is feeling the impact of climate change in terms of increased instances of heat waves which are more intense in nature with each passing year, and have a devastating impact on human health thereby increasing the number of heat wave casualties
Heat waves occur wherever a mid-level high-pressure system develops over an area. This high-pressure system forms a “cap” over the affected area, trapping heat that would otherwise rise into the air to cool off before circulating back to the surface. This reduces the chance for precipitation to form, and the result is just a continual build-up of heat.
These high pressure systems are slower to change during the summer. This means the heat can linger on and on, and why temperatures may not cool off enough at night to offer a sense of relief.
- Increased human morbidity and mortality, particularly among the elderly and infirm.
- Stress for outdoor workers.
- Increased bushfire risk.
- Stress in animals;
- Damage to crops and vegetation;
- Increased energy demand, e.g. greater demand for air conditioning;
- Stress on energy supply infrastructure;
- Increased demand for water, e.g. human consumption, cooling in power stations, evaporative cooling in homes and offices;
- Infrastructure stress: buildings, roads, rail and other infrastructure;
Climate change and Heat waves
While natural variability continues to play a key role in extreme weather, climate change has shifted the odds and changed the natural limits, making heat waves more frequent and more intense.
Global warming is causing more frequent heat waves. Record-breaking temperatures are already happening five times more often than they would without any human-caused global warming.
If we continue to rely heavily on fossil fuels, extreme heat waves will become the norm across most of the world by the late 21st century. However, if we take major steps to reduce human greenhouse gas emissions, the number of extreme heat waves will stabilize after 2040. Either way, we will see more heat waves, but how much more depends on us.
Heat waves and India
The heat waves in India especially affect the states of Rajasthan, Punjab, Haryana, Uttar Pradesh, Madhya Pradesh, Andhra and Telangana, Maharashtra, Gujarat, Odisha etc.
If average world temperatures increase by between 1.5˚C and 2°C, potentially deadly heat waves are likely to substantially increase in frequency, and those similar to the one in 2015 could become an annual occurrence in India and Pakistan, according to a new report by the Intergovernmental Panel on Climate Change (IPCC), the United Nations body set up in 1988. At warming of over 2°C, coastal cities such as Karachi and Kolkata are especially at risk. Previous research has already shown that parts of Bangladesh, Pakistan, and India could soon become uninhabitable because of heat waves, which are now claiming more lives in India than ever before.
Heat wave management strategies as per NDMA guidelines
- Establish Early Warning System and Inter-Agency Coordination to alert residents on predicted high and extreme temperatures. Who will do what, when, and how is made clear to individuals and units of key departments, especially for health.
- Capacity building / training programme for health care professionals at local level to recognize and respond to heat-related illnesses, particularly during extreme heat events. These training programmes should focus on medical officers, paramedical staff and community health staff so that they can effectively prevent and manage heat-related medical issues to reduce mortality and morbidity.
- Public Awareness and community outreach Disseminating public awareness messages on how to protect against the extreme heat-wave through print, electronic and social media and Information, Education and Communication (IEC) materials such as pamphlets, posters and advertisements and Television Commercials (TVCs) on Dos and Donts and treatment measures for heat related illnesses.
- Collaboration with Non-Government and Civil Society: Collaboration with non-governmental organizations and civil society organizations to improve bus stands, building temporary shelters, wherever necessary, improved water delivery systems in public areas and other innovative measures to tackle Heat wave conditions.
Test yourself: Mould your thoughts
Discussing the regions affected by heat waves in India, list out important preventive and preparatory measures.