A study conducted by the Interdisciplinary Climate Research Centre (ICRC) of Cotton University has confirmed that North East India has warmed significantly during the last hundred years.
The rise in surface temperature has been primarily due to rapid increase in both the maximum as well as minimum temperatures, with the minimum temperature increasing more rapidly in the entire region.
Disclosing this, Dr Rahul Mahanta, coordinator of the ICRC of Cotton University told this Correspondent that the minimum temperature is rising in the NE region due to rise in greenhouse gases in the atmosphere.
He said the average highest temperature over NE India used to occur during April-May Spring season and surface temperature drops with the onset of the monsoon due to extensive cloud cover and rainfall activities, which are associated with monsoon circulation.
The temperature trends for all the seven NE states and their districts were calculated by the ICRC, which are significant at 10 per cent level. The Intergovernmental Panel on Climate Change (IPCC) in its Assessment Report (AR) 4 has categorised five per cent significance as extremely ‘likely’ and 10 per cent significance as ‘very likely’.
Maximum temperature trends over the entire NE region of India increased almost at the rate of one degree celsius per century during the past 200 years. States like Assam, Arunachal Pradesh and Nagaland showed an increase of 0.78 degree celsius in their respective maximum temperatures per 100 years during this period, while Meghalaya, Tripura and Mizoram showed a steady increase of 0.55 degree celsius per 100 years during the same period. However, during the same period, Manipur showed an increase of 0.62 degree celsius per 100 years.
In magnitude, Assam and Arunachal Pradesh showed the highest trend in maximum temperature in winter, even as maximum temperature in the pre-monsoon season increased by 0.9 degree celsius per 100 years in Arunachal Pradesh, followed by Assam with an increase of 0.82 celsius per 100 years.
The findings of the ICRC study has revealed that maximum upward change in maximum temperature were observed in the month of February, followed by the months of November and December, over the entire NE region during the past 100 years since 1890 AD.
Likewise, the months of November, December and February have shown maximum increase in the minimum temperature with values of 0.87 degree celsius, 1.1 degree celsius and 1.25 degree celsius respectively, per 100 years over the entire North East region.
On the other hand, the monsoon months of June, July, August and September showed a decrease in the minimum temperature in Manipur and Meghalaya and an increase in Arunachal Pradesh and Nagaland. However, these trends are not significant statistically, Dr Mahanta said.