Climate-change factors are likely to turn Kerala into a warmer region in the years to come, with an erratic monsoon behaviour marked by decreasing overall rainfall and an increase in the frequency and severity of extreme rainfall events.
A study that was compiled by the Institute of Climate Change Studies, Kottayam, shows a decreasing trend in average rainfall over Kerala, especially during the monsoon seasons.
Intense rainfall events
Citing rainfall observations during the period from 1901 to 2015, the study by Abhilash S. and Krishnakumar E.K. of the Cochin University of Science and Technology (Cusat) also noted an increase in the number of intense rainfall events.
The observations in the study pointed to a shift in the rainfall peak towards the latter part of the monsoon, with the rainfall following a decreasing trend during June-July and an increasing trend during August-September.
Shift in pattern
The observed spatial rainfall trend also showed a shift in the rainfall pattern towards the northern parts of the State.
Citing the IPCC’s Climate model inter-comparison project Phase 5 (CMIP5) models, they contend that rainfall over Kerala would become more and more erratic in nature, with a plausible decrease in overall rainfall and increase in extreme weather events. According to their projections for the period from 2017 to 2030, south Kerala is likely to register a decrease of 3% to 5% in the rainfall during the southwest monsoon from June to September while the rainfall over the northern districts may increase by 2% to 4%.
Post-monsoon season
During the post-monsoon season from October to December, south Kerala may witness an increase in rainfall of 6% to 10% and a decrease of 2% to 5% over north Kerala.
The projection of monsoon rainfall for the period 2030-2060 shows an increasing trend almost all over Kerala, with small pockets of decreasing trend.
The study also indicates that Kerala is likely to experience more heat wave conditions over the period from 2017 to 2030.
The maximum temperature may go up by 0.3 to 0.6 degree Centigrade during the pre-monsoon season.
The minimum temperature is also likely to go up by 0.5 to 1.0 degrees during January- February, as per the study.
Warming trend
According to the long-term projection for the period 2031-2060, the minimum temperature in Kerala is likely to increase by 1.5 to 2.0 degrees, signalling the shift to a warmer climate in future.
The study also predicts an increase in the weather hazards associated with pre-monsoon thunder clouds over Kerala.
Surface heating
The increased surface heating and moisture content could trigger more frequent and severe lightning strikes, flash floods, cloud bursts, and micro bursts in future, it warns.