Indian summer monsoon weakening, say scientists
[NEW DELHI] The Indian summer monsoon is weakening, a new study shows, which could spell trouble for poor farmers who are dependent on rainfall.
Researchers from the Centre for Atmospheric Sciences at the Indian Institute of Technology (IIT), Delhi, analysed rainfall data collected by the Indian Meteorological Department for the period 1951–2004. They examined possible changes in the frequency, duration and intensity of rainfall events, dividing the country into six rainfall zones as defined by the Indian Institute of Tropical Meteorology, Pune.
Overall, long rainy spells — more than 2.5 millimetres of rain daily for more than four consecutive days — decreased across the country over the last 50 years while short and dry spells — less than 2.5 millimetres of rain daily for a day or so — increased.
"Significant decrease in the number of long spell rain events and simultaneous increase in the short and dry spells over India suggest that monsoonal systems have weakened," the scientists conclude.
Sushil Kumar Dash, lead author and a professor at IIT, told SciDev.Net that his team are concerned about their findings.
"Lengths of [rainy] spells affect agricultural practices to a great extent. We are also concerned about the changes in temperature over India. With India being predominantly an agricultural country, it is essential to examine regional changes in rain and temperature in order to assess the agricultural risk management in [light of] the warming atmosphere."
Saudamini Das, an economist at the University of Delhi, says her team's preliminary agricultural analysis for agriculture indicates that the summer monsoon has both weakened and become erratic, and it has put a heavy economic burden on poor Indian farmers who are mostly dependent on rainfalls.
"[Farmers] are resorting to different cropping patterns, pump irrigation and other agricultural practices as adaptive measures and all these have increased the cost of production in agriculture. The farmers most adversely affected are the ones where groundwater tables are very low," she told SciDev.Net.
The research was published online on 29 May in the Journal of Geophysical Research Atmopsheres
J. Geophys. Res., 114, D10109, doi:10.1029/2008JD010572 (2009)