The topic assumed importance when Prime Minister Manmohan Singh, in his inaugural address on Wednesday, asked scientists to engage in exploring the links between greenhouse gas emissions and climate change. He also wanted them to examine its impact on monsoon rains and emphasised on the need to upgrade weather forecasting systems, which can help farmers.
The president of the Indian Science Congress Harsh Gupta quoting a recent detailed study done by BM Goswami and his colleagues at Punes Institute of Tropical Meteorology said, The study shows a significant rise in the frequency and the magnitude of extreme rain events and decreasing trend in the frequency of moderate events over central India. It also points that the seasonal mean rainfall does not show a significant trend as contribution from extreme event is compensated by a decrease in moderate events.
Monsoon system, although quite stable, shows intricate pattern of space-time variability, leading to floods and droughts. The causes of this variability is partly due to heating in the Bay of Bengal and also due to El Nino phenomena (warming of Pacific waters). Thus, according to the study both local and global dimensions of the problem are involved. In 2005 and 2006, the country had witnessed a unique shift in the monsoon rainfall pattern, heavy rains in drought-prone areas and low rainfall in flood-prone areas. Particularly, the west coast of the country received heavy rains, leading to floods at places
According to Manish Tiwari of the Goa-based National Centre for Antartic & Ocean Research (NCAOR), a recent high-resolution study has shown that the increase in rainfall over the west coast coincided with the first step of de-glaciation in central Asia and Tibetan plateau which enhanced the land-sea air pressure difference during summer.
In 2005 and 2006, the country had witnessed a unique shift in the monsoon rainfall atternheavy rains in drought-prone areas and low rainfall in flood-prone areas The monsoon system does show an intricate pattern of space-time variability, leading to floods and droughts Futuristic projections show that annual rainfall will increase by 3.4% in the Nilgiris and by 47% over Umiam, while winter rains will decrease in Tehri Garwal
The study was done for the period 2071-2100. Futuristic projections show that annual rainfall would increase by 3.4% in Nilgiris in Tamil Nadu and by 47% over Umiam in Meghalaya, while winter rains would decrease over Tehri Garwal. Monsoon rains would decrease over Nilgiris and Poglur in Tamil Nadu and post-monsoon rains would decrease over Almas, Antisar in Gujarat.