Mitigating Impact of Oppressive Heatwaves

In recent years, climate researchers have increasingly focused on the rising frequency and intensity of heatwaves in India. A joint study conducted by the Indian Institute of Technology (IIT) Bombay and ETH Zurich highlights the phenomenon of ‘oppressive heatwaves,’ which pose severe threats to public health. These heatwaves are characterized by a combination of high temperatures and elevated humidity levels, making them particularly hazardous. The study also warns that future heatwaves will become more severe due to the ongoing effects of global warming.

What is a Heatwave?

A heatwave refers to a prolonged period of excessively high temperatures, often resulting in adverse health and environmental impacts. The India Meteorological Department (IMD) defines a heatwave based on specific temperature thresholds:

• In plains, a heatwave is declared when the temperature exceeds 45 degrees Celsius for at least three consecutive days.
• In hilly regions, the threshold is slightly lower, at 40 degrees Celsius.

Types of Heatwaves

Researchers categorize heatwaves into two distinct types based on temperature and humidity levels:

1. Oppressive Heatwaves

These heatwaves occur when both temperature and humidity levels are high. The presence of excessive moisture in the air makes it difficult for the human body to cool down through sweating, increasing the risk of heat exhaustion and heatstroke.

2. Extreme Heatwaves

Unlike oppressive heatwaves, extreme heatwaves are characterized by extremely high temperatures but low humidity. These events are more common in arid and semi-arid regions where dry heat prevails.

Understanding the distinction between these two types is crucial, as they have different physiological and environmental impacts.

Historical Data and Analysis

To assess the impact of heatwaves, researchers analyzed historical temperature data spanning from 1951 to 2013. This data was sourced from the IMD and other meteorological agencies. Key findings include:

• A significant increase in the number of heatwave days over the decades.
• A strong correlation between oppressive heatwaves and rising mortality rates.
• A study of heat-related mortality from 1967 to 2007 confirmed that the number of deaths increased during oppressive heatwave events.

These historical trends underscore the growing threat posed by extreme temperature events and emphasize the need for immediate climate action.

Future Projections of Heatwaves

The study also examined future projections of heatwave occurrences under different global warming scenarios:

• If global temperatures rise by 1.5 degrees Celsius (relative to pre-industrial levels), the frequency of oppressive heatwave days could increase five-fold by the end of the 21st century.
• If global temperatures rise by 2 degrees Celsius, the number of oppressive heatwave days could increase eight-fold, making large parts of India uninhabitable during peak summer months.

Health Implications of Oppressive Heatwaves

The impact of oppressive heatwaves on human health is severe and multifaceted:

• Increased risk of heat-related illnesses: Prolonged exposure to high temperatures and humidity can lead to dehydration, heat exhaustion, and life-threatening heatstroke.
• Higher mortality rates: Vulnerable populations, including the elderly, children, and individuals with pre-existing health conditions, are at greater risk.
• Workforce productivity loss: Outdoor laborers, such as farmers and construction workers, face extreme working conditions, leading to economic disruptions.

Role of Global Warming in Intensifying Heatwaves

Climate change is a major driver of the increasing frequency and intensity of heatwaves. The study emphasizes that limiting global warming to 1.5 degrees Celsius could significantly reduce the risk:

• 44% decrease in oppressive heatwaves.
• 25% reduction in extreme heatwaves.

These projections highlight the urgent need for climate action and policy measures to mitigate the impact of heatwaves on human health and the environment.

Mitigation and Adaptation Strategies

Given the alarming projections, proactive steps are necessary to reduce the impact of heatwaves. Some key strategies include:

1. Urban Planning and Green Spaces

• Increasing green cover in cities to reduce the urban heat island effect.
• Implementing cool roof and reflective pavement technologies.

2. Public Health Measures

• Early warning systems to alert people about impending heatwaves.
• Public awareness campaigns to educate citizens on heatwave safety measures.

3. Government Policies and Climate Action

• Strengthening climate policies to curb greenhouse gas emissions.
• Investing in renewable energy sources to reduce reliance on fossil fuels.