Heat and drought linked to climate change have already reduced yields of maize, wheat and soybeans by an estimated $20 billion a year. Researchers project these losses could rise sharply to more than $160 billion annually by 2100 in a high-emissions scenario. The findings were presented at the European Geosciences Union meeting in Vienna in May.
A study led by Yi Ling Hwong and Kai Kornhuber at the International Institute for Applied Systems Analysis used historical yield data from the UN Food and Agriculture Organization and climate records to calculate the effects. It found a 3.5 per cent decline in yields between 2007 and 2019 compared with the 1974 to 2004 baseline, resulting in annual production losses of around 855 million tonnes.
The economic impact was calculated using past FAO price data. Losses are expected to hit major producers such as the United States hardest in absolute terms, while low-income countries where farming employs most of the population will feel the effects most acutely.
In the SSP3-7.0 high-emissions pathway, global yields of the three crops could fall by about 35 per cent by 2100, pushing annual financial losses above $161 billion. The researchers noted that the figures exclude other climate impacts such as floods and storms, and assume some adaptation by farmers.