Researchers from IIT-Bombay and ETH Zurich have identified a new type of heatwave called ‘oppressive heatwaves’, which are caused by a combination of high temperature and high humidity. These heatwaves are expected to occur more frequently due to global warming, so it is important to be prepared.
Historically, heatwaves have been defined based on temperature thresholds exceeding a certain level for a specific period. In India, the India Meteorological Department (IMD) defines a heatwave as three or more days with temperatures exceeding a predetermined threshold based on the topography of the region.
The researchers analyzed historical data on heatwaves in India and looked at their association with human mortality. They classified heatwaves into ‘oppressive’ (high temperature and high humidity) and ‘extreme’ (high temperature and low humidity) categories. By examining future projections under different global warming scenarios, they found that oppressive heatwave days are likely to increase significantly compared to extreme heatwave days.
Under the scenario of a 1.5-degree Celsius increase in global temperatures, there is a five-fold increase in the number of oppressive heatwave days by the end of the century. This number further rises to an eight-fold increase under a 2-degree Celsius warming scenario. Limiting global warming to 1.5 degrees Celsius can reduce the likelihood of oppressive and extreme heatwaves by significant percentages.
The researchers also studied the association of heat-related mortality with oppressive and extreme heatwave days and found a strong positive relationship with oppressive heatwave days. This highlights the urgent need for adaptation measures to mitigate the impacts of these heatwaves, especially in densely populated regions.
In conclusion, the study emphasizes the increased risk of oppressive heatwaves due to global warming and stresses the importance of taking proactive measures to address this growing threat.
