This story is from October 4, 2016

Pune temperature rose faster than most cities in 40 yrs

Pune is among ten major cities in the country where the annual mean temperature has risen significantly higher than other cities over the last four decades.
<arttitle><p>Pune temperature rose faster than most cities in 40 yrs</p></arttitle>
(Representative image)
PUNE: Pune is among ten major cities in the country 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 Organization in Geneva, Switzerland, lists Pune along with Delhi, Kolkata, Jaipur, Ahmedabad, Mumbai, Nagpur, Bengaluru, Hyderabad and Chennai as cities with the significant temperature rise from 1971-2013.
The highest rise in mean temperature was in Jaipur (0.38°C), fol lowed by Bengaluru (0.23°C) and Nagpur (0.21°C).
The study showed that even hill stations like 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, maxi mum and minimum temperature data of 36 weather stations right from 1901. These stations were classified into four groups -major, medium, small cities and hill stations.
“Less than 50% stations from each group showed a significant increasing trend in annual mean temperature from 1901-1970. However, in the 1971-2013 period, more than 80% stations from all the groups, except the small city group, showed a significant increasing trend. The minimum temperature increased faster than the maximum in major and medium cities, while maximum temperature increased faster than minimum in the small cities and hill stations,“ said IITM's D R
Kothawale, who also headed the research.
The research was recently published in the American Journal of Climate Change. Nayana Deshpande from IITM and Rupa Kumar Kolli from the World Meteorological Organization, Geneva, were co-researchers.
Kothawale said that the rise in maximum temperature was slower in major and medium cities because the increase depends on factors such as solar radiation and aerosol concentration in a particular region. “Our analysis revealed that urbanization played a substantial role in contributing to the rise in temperatures in most major cities during the recent period. The effects of urbanization are more apparent on the minimum temperature in big cities. Greater concentration of multistorey buildings obstructs solar radiation coming from the sun during daytime.They also hinder terrestrial radiations going to the sky at night. This causes lowering of the day temperature and a rise in the night temperature,“ Kothawale said.
He 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 in creasing 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.
“What is clear is that during the past period, 1901-1970, when urbanization was not rapid, only three major cities -Kolkata, Surat and Mumbai -showed a significant increasing trend in mean temperatures while four major cities -Ahmedabad, Delhi, Jaipur, Hyderabad -showed a decreasing trend,“ Kothawale said. Among the hill stations studied, all showed a significant increasing trend in annual mean temperature during the entire period.
“However, increasing trends are mainly due to pronounced warming during the recent period, that is from the 1970s. From 19011970, only two stations, Shimla and Darjeeling, showed a significant increasing trend.However, from the 1970s, four stations showed a significant increasing trend,“ Kothawale said.
The maximum and minimum temperatures in winter have increased in all hill stations studied, except Kodaikanal, where the minimum temperature showed a significant decreasing trend.
The annual maximum temperature in the hill stations show a gradual increase up to 1970, and rapid increase from 1971to 2010.
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About the Author
Neha Madaan

Neha Madaan is a senior feature writer at The Times of India, Pune. She holds an M A degree in Mass Communication and Journalism from University of Pune. She covers tourism, heritage development and its conservation, apart from an array of subjects such as civic issues, environment, astronomy, civic school education as well as social issues concerning persons with disabilities. Her interests include metaphysical research and animal rights.

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