BANGALORE: An overcast sky, rain every day and all the fun which comes with the season are knocking at the door. The monsoon is predicted to hit the city by May 25, five days ahead of the normal onset. Pre-monsoon rain is already soaking the city every evening.
But studies and experts say the summer monsoon is shrinking and rainfall required for agriculture is increasingly becoming unpredictable. Distribution is also disturbed. While farmers are preparing to adapt to these changing patterns, what is in store for this year could vary a lot from the predictions.
IPCC data and all other international predictions have cited climate change will cause intense rainfall and increase risk of floods. Last year's unusually high rainfall in Karnataka was also believed to be an impact of the same. According to professor, agro-met department, UAS, Raje Gowda, the sowing season has shifted by at least 20 days for farmers. "There are no such changes in the onset and offset of the monsoon but the precipitation useful for agriculture has become unpredictable. Some years, when the rainfall in June and July is not adequate, we ask them to sow in August," he says.
The North-East monsoon in October helps in completing the harvest in such cases. The quantum of rainfall is also unexpected. "Mumbai received 990 mm in 20 hours, we received 160-170 mm rainfall in 20 hours here last year. Intense rain is increasing but the dry spell areas are also increasing as distribution is not even," he added. Distribution predictions for this year for four zones of the state will be released next week by the department.
A study by K V Ramesh and P Goswami of the Centre for Mathematical Modelling and Computer Simulation in Bangalore confirms the summer monsoon has shrunk. It is an analysis of daily gridded observed rainfall data from 1951 to 2003. There are decreasing trends in both early and late monsoon rainfall and number of rainy days, implying a shorter monsoon over India.
For the pre-June period, decrease in the area-averaged rainfall and number of rainy days are 59% and 47% respectively, of the mean values. For post-monsoon period, the corresponding values are smaller (39% and 24% respectively) but still significant. It also confirms that length and coverage of the Indian summer monsoon is decreasing.
A reason attributed to such changing patterns is the increasing surface temperature of oceans. Director of meteorological department, Bangalore, A Muthuchami, confirmed surface temperature of the Indian Ocean has increased by 1 degree. This could be due to pollution in the ocean. If the ocean gets warmer, rainfall is delayed and is much more intense.
