In recent years, researchers have increasingly focused on the growing frequency of heatwaves in India. A study conducted by IIT-Bombay and ETH Zurich highlights the phenomenon of ‘oppressive heatwaves’, characterized by high temperatures combined with high humidity. This lethal combination significantly elevates health risks, and the study suggests that future heatwaves will become more severe due to global warming.
Definition of Heatwaves
Heatwaves are periods of excessively high temperatures that can have severe environmental and health consequences. According to the India Meteorological Department (IMD), a heatwave is defined as three consecutive days with temperatures exceeding specific thresholds:
- Plains: Above 45 degrees Celsius
- Hilly regions: Above 40 degrees Celsius
Types of Heatwaves
Researchers classify heatwaves into two main categories:
- Oppressive Heatwaves: Characterized by both high temperature and high humidity, leading to extreme physiological stress on the human body.
- Extreme Heatwaves: Occur with high temperatures but low humidity, which can still be hazardous but with different impacts on health and the environment.
This distinction is crucial in understanding the varied health effects associated with these weather phenomena.
Historical Data Analysis
The study utilized historical temperature data from 1951 to 2013, sourced from the IMD and other meteorological agencies. Additionally, the researchers examined heatwave-related mortality records from 1967 to 2007, finding a strong positive correlation between the number of oppressive heatwave days and increased mortality rates.
Future Projections
Using climate models, the study projected the occurrence of future heatwaves under two global warming scenarios—1.5 degrees Celsius and 2 degrees Celsius increases relative to pre-industrial levels:
- At 1.5 degrees Celsius warming, oppressive heatwave days could increase five-fold by the end of the century.
- At 2 degrees Celsius warming, this increase could reach eight-fold, leading to an alarming rise in heatwave-related deaths.
Health Implications
As oppressive heatwaves become more frequent and intense, the study warns of a significant rise in heat-related mortality. Vulnerable populations, such as the elderly, children, and outdoor laborers, face heightened risks. Researchers emphasize the urgent need for adaptation measures, including improved urban planning, increased green cover, and efficient cooling strategies to mitigate these threats.
Global Warming and Heatwaves
Limiting global warming to 1.5 degrees Celsius could have substantial benefits:
- A 44% reduction in the likelihood of oppressive heatwaves.
- A 25% decrease in extreme heatwave occurrences.
These findings highlight the critical importance of climate action in protecting vulnerable populations from the devastating impacts of extreme heat. Policymakers must prioritize sustainable climate strategies to curb the frequency and intensity of heatwaves, ensuring a safer future for all.