ISLAMABAD: Wheat yield in South Asian countries, including Pakistan, is feared to decline by 16 per cent by 2050 due to climate change, reveals a new study released by the International Maize and Wheat Improvement Centre (CIMMYT) on Saturday.

Simulations for South Asian countries suggested a different magnitude of climate change impacts with India and Pakistan being the most affected countries with a general decline of wheat yields of 16pc, particularly due to warmer temperatures. However, areas in western Iran, Afghan­istan, Nepal, and Myanmar could experience a positive response to climate change.

Climate change will lower global wheat production by 1.9pc by mid-century, with the most negative impacts occurring in Africa and South Asia, according to the research.

The wheat simulation models have been widely used to study diverse cropping systems around the world, based on which studies have already shown that wheat yields fell by 5.5pc during 1980-2010, due to rising global temperatures, says the wheat crop modeller at CIMMYT.

However, the study says introducing crop genetic traits (CGT) as an adaptation to climate change improved wheat yield in many regions, but due to poor nutrient management, many developing countries only benefited from an adaptation from CGT when combined with additional N fertilizer.

As growing conditions and the impact of climate change on wheat vary across the globe, region-specific adaptation strategies need to be explored to increase the possible benefits of adaptations to climate change in the future.

Several factors, including temperature, water deficit, and water access, have been identified as major causes of recent wheat yield variability worldwide. The wheat models simulate the impact of temperature, including heat stress, water balance, drought stress, or nitrogen leaching from heavy rainfall.

Climate change at high latitudes (France, Germany, and northern China, all large wheat-producing countries/region) positively impacted wheat grain yield, as warming temperatures benefit wheat growth through an extended early spring growing season.

But warmer temperatures and insufficient rainfall by mid-century, as projected at the same latitude in Russia and the northwestern United States, will reduce rain-fed wheat yields — a finding that contradicts outcomes of some previous studies.

At lower latitudes that are close to the tropics, already warm, and experiencing insufficient rainfall for food crops and therefore depending on irrigation (North India, Pakistan, Bangladesh), rising heat will damage wheat crops and seriously reduce yields.

China, the largest wheat producer in the world, is projected to have mixed impacts from climate change but, at a nationwide scale, the study showed a 1.2 per cent increase in wheat yields.

Extreme weather events could also become more frequent. Those were possibly underestimated in the study, as projections of heat damage effects considered only changes in daily absolute temperatures but not possible changes in the frequency of occurrence.

The study was supported by the CGIAR Research Programme on Wheat agri-food systems, the CGIAR Platform for Big Data in Agriculture, the International Wheat Yield Partnership, the Bill & Melinda Gates Foundation, the World Bank, the Mexican government and the European Union.

Published in Dawn, June 25th, 2023