IMPHAL, Sept 22 - Urbanisation in the Northeastern states in the last 30 years has led to increase in the night-time temperature. This is because of the urban heat island effect, as the buildings and streets absorb energy during the day and release it at night, thus increasing the temperature.
This was stated by Prof Manju Mohan of Indian Institute of Technology (IIT), Delhi, while speaking on ‘Impacts on microclimatic conditions from changing land-use, land-cover patterns – Relevance to the Northeastern region’ during a research policy workshop on climate change held in Imphal.
The workshop held at the Manipur University campus and at a hotel in Imphal was jointly organised by Central Agricultural University (CAU), National Institute of Technology (NIT) Manipur and Manipur University in association with the Directorate of Environment, Manipur.
Prof Manju said they analysed the seasonal trends of temperature and rainfall over the North East during the last century, based on data obtained from nine stations of the India Meteorological Department (IMD) in the North East – which are at Agartala, Cherrapunji, Dibrugarh, Gangtok, Guwahati, Imphal, Pasighat, Shillong and Silchar.
“Significant increasing trend has been observed for minimum temperature for all the IMD stations of the North East region except Cherrapunji,” said the IIT professor. “The rate of increase in minimum temperature has been found to be higher over Shillong.”
Similarly, the maximum temperature for all the IMD stations shows a generally increasing trend or no significant trend except Gangtok during all the four seasons and Agartala during the pre-monsoon season where it shows a deceasing trend, she said. “The rate of increase in maximum temperature is found to be higher over Imphal during the monsoon season and over Cherrapunji in the post-monsoon season,” she said.
The possible reasons for all these changes could be because of deforestation and degradation of forest cover, increase in the population in the past half century leading to increased anthropogenic heat over the populated areas and increase in greenhouse gases, besides global warming, she observed.
Interestingly, almost all the IMD stations show either a decreasing trend of rainfall or there is no significant trend except Guwahati during the post-monsoon season where it shows significant increasing trend. She said there was a decreasing trend in the annual rainfall in the Brahmaputra basin, while there was an increase in the lower North East. There was also a decrease in the annual number of rainy days all across the North East.
The programme was attended by Prof N Rajmuhon of MU, Prof L Nabchandra of CAU, Dr Ng Romejit Singh of NIT, Dr I Meghachandra of ICAR, Imphal, Dr H Birkumar of CSIR, Dr T Brajakumar of the environment department among others.