New Delhi: Each degree Celsius increase in the global mean temperature would, on average, reduce global yields of wheat by 6%, rice by 3.2%, maize by 7.4% and soybean by 3.1%, says a study.

The study was published in the US scientific journal ‘Proceedings of the National Academy of Sciences’ (PNAS) on Tuesday.

Noting that crops are sensitive to climate change, including changes in temperature and precipitation, the study explained that among the changes temperature increase has the most likely negative impact on crop yields.

“Wheat, rice, maize, and soybean provide two-thirds of human caloric intake. Assessing the impact of global temperature increase on production of these crops is therefore critical to maintaining global food supply..," the study said.

“Results from the different methods consistently showed negative temperature impacts on crop yield at the global scale, generally underpinned by similar impacts at country and site scales..," the study said.

Among the four crops—wheat, rice, maize and soybean—loss in yield for each degree Celsius increase in global mean temperature is largest for maize.

“The impact estimates are consistently negative for four major maize producers, together responsible for two-thirds of global maize production—United States, China, Brazil and India," it added.

For wheat, the study said estimated yield losses for “India and Russia are more vulnerable to temperature increase".

The study stressed that “impacts of increasing temperatures on major global crops show substantial risks for agricultural production, already stagnating in some parts of the world. However, differences in temperature responses of crops around the world suggest that some mitigation could be possible to substantially affect the magnitude (or even direction) of climate change impacts on agriculture."

It, however, noted that these impacts will also vary substantially for crops and regions and highlighted that a “reinvigoration of national research and extension programs is urgently needed to offset future impacts of climate change, including temperature increase on agriculture by using crop- and region-specific adaptation strategies".

To control the rise in global temperature, the world finalized a new global climate deal, ‘Paris Climate Agreement’ in December 2015, which aims to limit rise in global temperature well below 2 degrees Celsius over pre-industrial times and make efforts to limit it to 1.5 degrees Celsius above pre-industrial levels by the end of 2100.

The study noted that, “farmers have increased yields through adapting new technologies during the last half-century, but yield has been also lost through increases in temperatures already".

“Yield increase has slowed down or even stagnated during the last years in some parts of the world, and further increases in temperature will continue to suppress yields, despite farmers’ adaptation efforts," it added.