Source: Earth’s Future
On the basis of current carbon emissions rates and climate policies, average global temperatures are projected to increase to 2.9°C above preindustrial averages by the end of the century. Such an increase would severely strain global agriculture, making large tracts of current production areas unsuitable for crops and livestock. At the same time, the Food and Agriculture Organization of the United Nations estimates that food production needs to increase by 70% to keep pace with population growth.
In the absence of notable emissions reductions, some observers have suggested such geoengineering strategies as carbon dioxide removal and solar radiation modification as alternative approaches for curbing warming. However, the effects of these strategies on food production remain largely unexplored.
Grant et al. researched how stratospheric aerosol injection (SAI)—a geoengineering approach that mimics the effects of volcanic eruptions by releasing sulfate particles into the stratosphere to reflect incoming solar radiation—could affect agriculture in India, which has more total cropland than any other nation in the world. Agriculture employs 45% of the country’s labor force and generates more than $50 billion in exports each year.
The authors compared two climate simulations, both of which account for climate change, through the year 2069. In the first, the Assessing Responses and Impacts of Solar Climate Intervention on the Earth System with Stratospheric Aerosol Injection (ARISE-SAI-1.5) experiment, the inclusion of SAI limits warming to 1.5°C. The other, which follows Shared Socioeconomic Pathway 2-4.5 (SSP2-4.5) and does not include SAI, projects conditions in which both emissions and temperatures rise compared to current levels. The authors then evaluated how each trajectory influenced such climatic indices as total precipitation and warm spell duration, which affect rice and wheat production.
The results suggested that the climate intervention scenario would improve rice and wheat yields in India relative to the nonintervention scenario—but with caveats. Chiefly, geoengineering helped maintain ideal temperature ranges for crop growth but did not alter climate change–induced precipitation extremes or drought. The results also suggested that rain-fed wheat would benefit more from intervention than irrigated wheat but that the effects on rain-fed rice would vary by region.
The authors say the study represents a step toward understanding the effects of such climate interventions as SAI on agriculture. But they stress that more research is needed in this area and that policymakers should continue to explore the consequences of interventions before deploying them. In lieu of climate intervention, the authors suggest that shifting planting dates could help mitigate impacts on agriculture on the Indian subcontinent. (Earth’s Future, https://doi.org/10.1029/2024EF005262, 2025)
—Aaron Sidder, Science Writer
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