As temperatures rise, crop yield goes south

The rise in temperature levels, which is a part of the climate change phenomenon, is affecting agricultural yield in a more direct way than observed previously, and is set to play a significant role in the coming days.

Experts from the Tata Institute of Social Sciences and the Indian Statistical Institute (ISI), who studied four major crops in Karnataka, have found that the yields were consistently and “significantly low” in cropping seasons when “exposure to temperatures above the critical thresholds was high”.

The study, commissioned by the Karnataka Agricultural Price Commission (KAPC), considered 33 degrees Celsius as the average critical threshold of temperature for paddy, jowar (sorghum), ragi and tur dal.

Madhura Swaminathan, professor and head of economic analysis at ISI Bengaluru, said the analysis of taluk-level data from the past 30 years showed that a 1% increase in the days with extreme temperatures contributed to a decrease in the yield of kharif paddy by over 5%.

“This is not a prediction. This is based on hard facts and long-term data where rain, temperature and yield were different every year. What we know now is that the climate change phenomenon requires us to develop new methods and techniques that help us act quickly, instead of reacting,” she said.

While previous studies have thrown light on the relationship between climate change and agriculture, the focus was more on drought. “It is probably a first-of-its-kind study for southern India, analysing the effects of high temperature. Previously, the wheat yield in the Indo-Gangetic plain was studied this way. We will soon take this model to Tamil Nadu, Telangana and other states,” she said.

KAPC chairman T N Prakash Kammardi said that between 2008 and 2018, there was a 30% decrease (18.34 lakh tonnes) in the total yield of paddy in the state. “The output has come down even in well-irrigated areas. There are various factors contributing to this downward trend. However, previously, the aspect of high temperature was not factored in. Now we know it is not just water that we have to focus on,” he said.

He said that considering that over 65% of the cultivated area in the state is dependent on rainfall, more studies were needed to assess the full magnitude of the threat posed by high temperatures.

Madhura said that different departments need to work together if they want to prepare for future challenges. “We need an interdisciplinary and well-integrated approach. At present, we get weather data every day, but data on yield at the end of the year. This won’t do. All kinds of data should be updated constantly, allowing quick analysis to prepare ourselves for climate change,” she said.