Delhi temperature rose faster than most cities in last 40 years

PUNE: Delhi is among 10 major cities in the country, which includes all big metros, where the annual mean temperature has risen significantly higher than other cities over the last four decades.

A recent study by the Indian Institute of Tropical Meteorology (IITM) and the World Meteorological Organisation in Geneva, Switzerland, lists Delhi along with Kolkata, Jaipur, Ahmedabad, Mumbai, Nagpur, Bengaluru, Hyderabad, Chennai and Pune as cities with significant temperature rise from 1971-2013. The highest rise in mean temperature was in Jaipur (0.38°C), followed by Bengaluru (0.23°C) and Nagpur (0.21°C). Delhi is among four cities in the list which showed a decrease in mean annual temperatures from 1901 to 1970, before the trend got reversed.

This indicates increasing urbanisation has played a role in rising temperatures, said IITM's D R Kothawale, who headed the research. The other cities showing a similar trend are Ahmedabad, Jaipur and Hyderabad.

The study showed that even hill stations such as Srinagar, Shimla, Darjeeling and Kodaikanal had recorded a rise in temperatures over the last 40 years till 2013. The maximum and minimum temperatures in these hill stations had gone up by 0.4°C and 0.22°C per decade.

The researchers used seasonal and annual mean, maximum and minimum temperature data of 36 weather stations right from 1901.

Kothawale also said that the annual mean temperature of all the coastal stations showed a significant increasing trend.

Nine major cities -Kolkata, Jaipur, Ahmedabad, Surat, Mumbai, Pune, Nagpur, Bengaluru and Chennai -showed significant increasing trends in minimum temperature after 1971, whereas the maximum temperature during this period showed a significant increasing trend in six major cities -Jaipur, Mumbai, Nagpur, Bengaluru, Hyderabad and Chennai.