Even in years of good rainfall and availability of water, soaring temperatures owing to climate change could significantly cut into the earnings of farmers, shows a study claiming to be the first of its kind in the State.
The variations in yield to temperature of paddy, jowar, toor, and ragi, which covers the major crops sown in the State, were scrutinised in the study “Climate variability and climate change in Karnataka”, commissioned by Karnataka Agricultural Price Commission (KAPC).
Unirrigated paddy, jowar grown during the rabi season (September to October), ragi and toor were found to be sensitive to exposure to extreme temperatures; and in the case of jowar, the effect of extreme heat was more than the effect owing to variation in rainfall. Not just that, consecutive days of extreme heat even negatively overwhelmed positive effects of good rainfall and average temperature.
“Roughly, even short-term exposures to extreme heat, where temperatures cross the critical limit for growth, of between eight to 21 days can lower yield of these crops,” said Kamal Kumar Murari, Assistant Professor at Tata Institute of Social Sciences in Mumbai, who along with his colleagues, T. Jayaraman, Sandeep Mahato, and Madhura Swaminathan from Indian Statistical Institute in Bengaluru conducted the study.
The team sought to look at the effect of global warming and climate change in the point of temperatures and not just rainfall which has been studied extensively. Taking taluk climatic data and crop yield data over the years, researchers looked at the impact of rainfall, temperatures leading to growth of cultivated crop, as well as extreme temperatures which surpass the “critical temperatures” of crops.
For instance, the critical temperature of paddy is on the lower end at 33C, while for toor and ragi, it is 35C. However, with the average temperatures of plainlands of Karnataka increasing at more than 0.75C every century, the extreme temperatures are now being seen at a greater frequency than ever. Often, the factor of extreme temperatures outweighs the negative impact of variable rainfall, the study found.
This is, however, only the first step to studying the effect of heat, and more crop-specific and block-level research needed to be done so that the State is prepared for climate change, said Ms. Swaminathan. “There is a shortfall of climate data, which is critical as temperature and rainfall vary in short spaces. This research is to find out the impact and prepare for the future...there is a need in learning how we can cope with climate change that will continue to exasperate issues afflicting agriculture,” she said.
KAPC chief T.N. Prakash Kammardi said that while climate change studies have so far focussed on water and rainfall, this study was commissioned to understand impact of heat itself. “The climate change challenge in all its aspects is emerging now. In the West, they have done extensive studies, but we have only started now...there are drought-resistent crops, but heat-stress resistent crops are yet to be developed,” he said.