Danger of Extreme Heat

Extreme heat is rapidly becoming one of the biggest threats to global food production, putting crops, livestock, fisheries and the livelihoods of billions of people at risk, according to a joint report by the Food and Agriculture Organization (FAO) and the World Meteorological Organization (WMO). According to a report, temperatures above 30 degrees Celsius (°C) are already reducing yields of major crops, while rising heat is threatening farm workers, livestock, fisheries, forests and agricultural incomes. The report describes rising temperatures as a “risk multiplier” for agriculture, worsening droughts, increasing wildfire risks and triggering wider disruptions across food systems. “The fingerprints of extreme heat on agriculture are already visible worldwide,” it says, based on a review of global scientific evidence and case studies. Most major food crops begin to suffer yield losses once temperatures exceed 30°C, the report says. It estimates that maize yields have already declined by 7.5 per cent for every 1°C of warming, wheat by 6 per cent and soybean by 6.8 per cent. Looking ahead, maize and wheat yields could fall by up to another 10 per cent for every additional degree Celsius of warming, the report warns. Heat-related declines in agricultural productivity are already reshaping land use. Between 1992 and 2020, about 88 million additional hectares were brought under cultivation across 110 countries to compensate for production losses caused by heat and related stresses, including drought. The report says this expansion generated an estimated 21.8 billion tonnes of carbon dioxide equivalent emissions, or 18.9 per cent of total landuse emissions in those countries. This creates a damaging cycle: climate change reduces farm productivity, more land is cultivated to maintain output, land-use emissions rise, and climate change worsens further. Rising temperatures are also affecting the combined productivity of land, labour and capital in farming. Since 1961, heat stress has reduced global agricultural productivity by about 21 per cent, wiping out nearly seven years of productivity gains. (