Heatwaves to get longer by 61% in 189 Indian cities
A research paper published by the World Resources Institute's (WRI) Ross Center for Sustainable Cities has predicted a significant increase in heatwave duration across 189 Indian cities. The study, supported by Bloomberg Philanthropies, suggests that the longest heatwave of the year could extend by 61% to 24.1 days at a global warming level of 3°C, compared to just 15 days at a warming level of 1.5°C.
Rising temperatures to increase cooling demand
The research, published on Thursday, also indicates that the number of heatwaves per year could rise from 4.1 days to 5.3 days with a corresponding increase in warming. This change would result in a 13% surge in cooling demand across India, measured in cooling-degree days (CDD). CDD are calculated as the number of degrees that a day's average temperature exceeds 18°C.
Global climate model predicts city-scale impacts
The study's findings are based on a downscaled global climate model (NASA Earth Exchange) covering 996 cities. The WRI stated that with over two-thirds of the world's population expected to live in cities by 2050, this new data provides a detailed view into potential climate futures. "This new statistical modeling method can make it easier to predict city-scale impacts from global data," the statement added.
Malaria-transmitting mosquitos and heatwave frequency
The researchers also found that a 3.0°C scenario would reduce the number of days optimal for malaria-transmitting mosquitos across India, primarily in the north and east. However, most cities in central and south India would see an increase. For instance, peak malaria days could decrease from 221.3 days at a 1.5°C level to 153.9 days at a 3°C level.
Kolkata to witness highest increase in heatwave frequency
The study estimates that Kolkata will experience the most significant rise in heatwave frequency and duration, with 5.4 heatwaves predicted per year at a 3°C scenario compared to 2.7 at a 1.5°C scenario. The longest heatwave days could increase to 23.9 days from 9.5 days with the corresponding change in temperature. Other cities like Delhi, Chennai, and Hyderabad are also expected to see similar trends with increased heatwave frequencies and durations.
Bengaluru and Mumbai show contrasting heatwave trends
Interestingly, Bengaluru is predicted to see a decrease in heatwave frequency to 3.8 heatwaves per year at a 3°C scenario from 4 at a 1.5°C level. However, the duration of its longest heatwave is expected to increase significantly. Mumbai, on the other hand, could experience a higher frequency of heatwaves but a slight reduction in the duration of its longest heatwave at the 3°C level compared to the 1.5°C level.
