Global warming is already inflicting substantial financial damage on key agricultural crops, with new research indicating annual losses exceeding £15.7 billion ($20 billion) due to heat and drought. The study, conducted by the International Institute for Applied Systems Analysis (IIASA) in Austria, focuses on three staple crops: maize, wheat, and soybeans. This figure is projected to surge dramatically, potentially reaching over £126 billion ($160 billion) annually by 2100 if current high-emissions trajectories are maintained.
While major agricultural producers, such as the United States, are expected to bear the largest financial brunt, the human impact will be most acute in lower-income nations. Yi Ling Hwong, a researcher at IIASA, highlighted that countries in sub-Saharan Africa, where a significant portion of the population relies on farming, could experience disproportionately severe consequences. Such impacts could trigger social unrest and increased migration, underscoring the urgent need for adaptation strategies.
The methodology involved analysing yield data for maize, wheat, and soya from the UN Food and Agriculture Organization (FAO), alongside historical climate data to calculate drought levels. By comparing past heat extremes and drought levels with yields from 1974 to 2004, researchers estimated the impact of these climatic factors. Their findings suggest that increased heat extremes and drought have led to a 3.5 per cent decline in yields globally between 2007 and 2019, relative to the 1974-2004 baseline. Kai Kornhuber, another IIASA team member, noted that while a 3.5 per cent drop might seem modest, it represents a significant disruption to the global food market and can precipitate severe regional crises.
Economic losses were calculated using FAO data on farmer payments for produce. Projecting future losses under various emissions scenarios, the study assumes some level of adaptation will occur. In a high-emissions scenario (SSP3-7.0), global yields are anticipated to fall by approximately 35 per cent by 2100, with annual production losses reaching around 855 million tonnes. This volume is roughly equivalent to the annual consumption of 2 billion people, according to Hwong, who presented these findings at a European Geosciences Union meeting in Vienna in May.
Researchers acknowledge that these projections could potentially underestimate the full scope of climate change's impact. The study is limited to three crops and does not account for damage from floods, storms, or excessive rainfall. Furthermore, it does not factor in the possibility that crop shortages could lead to substantial price increases, a phenomenon already observed with commodities like coffee and cacao. Experts like Jonas Jägermeyr from Columbia University and Karine Chenu from the University of Queensland suggest that while statistical models are effective for current and near-future assessments, computer models that simulate plant responses to rising CO2 and temperatures may offer more reliable long-term projections for vastly different environmental regimes by the end of the century.