Climate change is real and here: Extreme heat shrivels up India’s wheat harvest

Farm experts are more cautious in estimating the losses, as wheat output numbers are still to be calculated. “The yield could have dropped by 9-10 percent in some wheat-growing areas,” said Shweta Saini, senior consultant at the Indian Council for Research on International Economic Relations. “There’s no doubt the excessively high temperatures before the harvest were responsible for this (phenomenon).”

Wheat, like most other crops, is highly susceptible to changes in temperature. During the grain-filling stage, which occurs in March, the crop suffers a condition known as terminal heat stress if the mean temperature rises above 31 degrees Celsius, scientific studies show.

This year, March was the hottest in 122 years since the India Meteorological Department (IMD) started maintaining records. It comes after the extreme heat of March last year, which was the third warmest on record. At an average maximum nationwide temperature of 33.10 degrees, March 2022 heralded the early onset of summer, a trend that is becoming the norm.

One of the main reasons for this can be attributed to climate change, said DS Pai, director at the Kottayam-based Institute for Climate Change Studies. “There are other factors at play, such as local weather conditions like scanty rainfall, but higher temperatures due to global warming is an unfortunate reality,” Pai said.

Just-harvested wheat bales on a field in Khirongi village of Mainpuri district in Uttar Pradesh (Photo: Soumya Sarkar)

The climate crisis due to human activity is affecting many weather systems in every region across the globe, said the landmark Code Red scientific report released in August 2021 by the Intergovernmental Panel on Climate Change. India will suffer more frequent and intense heat waves, the report by the United Nations body of climate experts predicted.

“The heatwaves and humid stress will be more intense and frequent during the 21st century,” the report said about South Asia, which includes India. This is validated by actual temperature records maintained by the IMD.

This is not the first time that the winter wheat crop has been so effected. Under similar weather conditions in March 2010, yields slumped by as much as 26 percent in some areas of Punjab, according to research led by the Borlaug Institute for South Asia.

Latest research on crop productivity seems to indicate that heat stress is increasingly affecting grain output. There is a definite quantitative link between crop loss and heat stress indicators, according to a study by researchers at the Indian Institute of Technology Bombay.

“Based on statistical analysis of observed temperature and actual wheat production data, we show that the magnitude, frequency, and area-wise extent of agricultural heat stress events are increasing in India's wheat belt, with frequency showing the most pronounced trend,” the researchers said in an October 2021 study in the Advancing Earth and Space Science journal.

They have pointed at the likelihood of reduced wheat yield in the future, using latest climate model projections. Under global warming, chances of below-average wheat production would rise by 8 to 27 percent in a business-as-usual scenario, where greenhouse gas emissions are not cut down sharply, the researchers said.

“There is no doubt that extreme heat events are increasing in India,” said Mahesh Palawat, vice-president of meteorology and climate change at Skymet Weather Services, a private forecaster. “This is leading to heat stress in many regions.”

This year, cultivators who have sown wheat a little later have suffered more in terms of yield losses, farmers said. Wheat would have to be planted earlier than usual to avoid the heat stress in March, they said.

If summer continues to arrive early, the wheat cropping season would have to be advanced, which presents another set of problems. The window between the summer paddy crop and the sowing of wheat is already too narrow, which has seen farmers burning crop stubble in autumn, which leads to very high air pollution in the northern Indian plains, including the National Capital Region (NCR).

The three food-bowl states need to break out of the unsustainable rice-wheat cultivation cycle, experts have been saying for long. But for farmers, it’s easier said than done, as suitable alternatives are yet to be found.

And it’s not just wheat. Rice output too, has been impacted because of the change in rainfall patterns in the monsoon months, said Saini. “Extremely high rainfall interspaced with long, dry spells are affecting paddy cultivation as well,” she said.

In such circumstances, there is an urgent need to look for other areas to cultivate cereals in a manner where there is a marketable surplus among farmers, Saini said. The crisis precipitated by higher temperatures needs both short- and long-term solutions, agreed Skymet’s Palawat.

If this trend of falling yields continues, the country will have to formulate policies that ensure that nutritional security is not compromised. This can possibly be done by promoting other crops that have higher nutritional value, Saini said. “Given the malnutrition status in India, we would have to cultivate rice and wheat in large quantities for at least another decade. There’s no getting away from that,” she said.

Since the climate emergency is going to increasingly impact grain productivity, it is high time long-term strategies to reduce the country’s dependence on the three breadbasket states for most of its cereals, are evolved, experts said.