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India’s warming trend

New Delhi, February 04 (G’nY News Service): The year 2015 was the hottest ever recorded according to US Agencies National Oceanic and Atmospheric Administration (NOAA) and NASA, who released their data on 20th Jan, 2015. The month wise data released by NOAA and NASA showed an alarming result, 10 out of 12 months in 2015 broke the existing records. India too has seen a rising trend in temperatures and according to the India Meteorological Department, (IMD), New Delhi, 2015 has set its own record, being the third most hottest year in India since 1901.

Talking to the G’nY correspondent, Dr. R Krishnan, senior scientist, Indian Institute of Tropical Meteorology (IITM) Pune said that, “the El Niño affects large parts of the Pacific Ocean raising temperatures by 2 to 3oC.” He added that, “during 2015 sea surface temperatures were high all over the world and not only in the equatorial region. This time, it seems that the temperature rise went beyond the tropical region”.

In India, El Niño and La Niña years affect the number of heat and cold waves. These heat or cold waves also help in raising or lowering annual average surface temperatures. Talking to our correspondent, Dr. Victor Smetacek, senior scientist, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Germany, said that, “climate is a complex system of many interlinking regional effects – on one hand whereas CO2 levels have been steadily increasing, the accompanying average temperature increase is not as steady and has seen more ups and downs, caused, for example, by the El Niño.

“It also depends on data coverage, which is highly unevenly spread. Thus, if it gets hotter in a Blufsregion with low data coverage, such as Amazonia during the recent drought, then there are simply fewer data to document it; the opposite was the case with the California drought, which has recently ended. Last year was exceptionally warm but the years before that remained at their post 2010 high levels. Similar periods of rapid rise as in the last two years and slower rise before that have happened in the past decades. Running averages taken over several years even out these variations and indicate a clear warming trend over a century”.

He also added that “another factor counteracting warming is emission of sulphur gases that cool the atmosphere but choke the people and living organisms in general. It has been well documented that sulphur emissions over Asia have increased in the past years.”

For 2015, a combination of global warming and the El Niño effect are being blamed. Dr. Saran, Public Relations Officer, National Institute of Oceanography (NIO) Goa, speaking with our correspondent added that, “warm water pools are created on the East Australian coast due to high sea surface temperatures. While normally these move towards the Peruvian side of South America, in El Niño years there is not much temperature difference between these two sides and they stay there raising sea temperatures.”

Citi 2

The annual average surface temperature of Kalimpong has risen from 13.6oC in 1980 to 14.9oC by 2015.

The period of 1997-1998 was the last time when such a strong El Niño was observed. However, El Niño alone cannot be held responsible for the dramatic rise in temperatures. After the 1998 El Niño there seemed to be a slower rise in global warming but the rapid warming trends are back again and a cause of concern. Dr. Krishnan expressed, “people have started to understand that overall warming has increased”.

The World Meteorological Organization had warned in November last year that 2015 looked to be the hottest year on record. In their press release dated 25th November 2015, they had said that this will be due to global warming and a strong El Niño. They had also predicted that 2011-2015 were to be the warmest five-year period on record in the press release.

The year 2016 is predicted to be even warmer than 2015 according to scientists. Dr. Saran adds that, “2016 will also most definitely be hotter as the effects of El Niño will cascade into this year as well.” He feels, “the effects of El Niño do not occur overnight and it affects weather dynamics during and after, causing instability in weather patterns especially the Indian monsoon”.

This could spell bad news for India, being largely dependent on the monsoon for agriculture. Delayed or deficit monsoon could lead to widespread crop failure.

According to Indian Meteorological Department (IMD) data of decadal annual mean temperature of India from 1901 to 2011, a significant increase in temperatures can be seen (Fig 1). The warming trend is particularly clear after 1975. The recent years (dashed line) has been included to show a marked spurt upward. If the warming trend continues, this could perhaps be the warmest decade ever for India.

Fig. 1: Decadal increase in annual mean temperature of India

Fig. 1: Decadal increase in annual mean temperature of India

Data: IMD, Ministry of Earth Sciences.

Commenting on the monsoon Dr. Victor said that, “we are already experiencing a fundamental shift in the timing and intensity of the monsoon. Unseasonal rains can do a lot of damage to agriculture as happened in 2015. The only good news is that India will receive more rainfall over the annual cycle even if the pattern is no longer that of a rainy season separating summer from winter – gone will be the predictable monsoon”.

He is hopeful that preparations can be made to combat the changed scenario. Dr. Victor cautions that the Indian moisture increase is only a model prediction that cannot predict how monsoons and ‘western disturbances’ will affect each other. He adds that “ it is of the utmost urgency that an education campaign explaining the current climate and its future evolution in easy-to-understand animations illustrating the basic principles outlined above should be put in place.”

Fig. 2: Annual Mean Temperatures of select cities in India, 1880 - 2020

Fig. 2: Annual Mean Temperatures of select cities in India, 1880 – 2020


Fig.2 shows the annual mean temperature of major Indian cities, based on the data by National Aeronautics and Space Administration (NASA). Cities have been selected on the basis of their location to understand an all India temperature pattern. Warming trends is perceptible in all cities. However, the maximum increase can be seen in the coastal city of Mumbai, where the average annual temperature of 25.5oC in1900’s, has steadily climbed to over 28.5oC today. Projected to 2020, temperature trends of NASA show a further increase. Delhi too has also seen changes warming trends in temperature from 23.8oC to 26.5oC in a mere twenty year period from 1930-1950. Apart from large metropolitan areas, smaller cities are also marked by the rising temperature trends with Machilipatnam mapping an increase of two degrees from 27oC in 1970’s to 29oC in 2015. Several other cities also registered an increase in annual temperatures, with the exception of Cuttack, where temperature trends despite being positive, rising from 25.3oC in the 1900 to 25.8oC in 2000, isn’t exceptionally stark.

The year 2015 was the hottest year on record and 2016 is slated to be even hotter. Perhaps it is time that we made an urgent effort to comprehend how best we can combat the situation at ground zero.

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