Impacts on Indian Agriculture Due To Stratospheric Aerosol Intervention Using Agroclimatic Indices

[Geoengineering News]

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2024EF005262

Authors 

Nina Grant, Alan Robock, Lili Xia, Jyoti Singh, Brendan Clark

First published: 04 January 2025

https://doi.org/10.1029/2024EF005262

Abstract

Climate change poses significant threats to global agriculture, impacting food quantity, quality, and safety. The world is far from meeting crucial climate targets, prompting the exploration of alternative strategies such as stratospheric aerosol intervention (SAI) to reduce the impacts. This study investigates the potential impacts of SAI on rice and wheat production in India, a nation highly vulnerable to climate change given its substantial dependence on agriculture. We compare the results from the Assessing Responses and Impacts of Solar climate intervention on the Earth system with Stratospheric Aerosol Injection-1.5°C (ARISE-SAI-1.5) experiment, which aims to keep global average surface air temperatures at 1.5°C above preindustrial in the Shared Socioeconomic Pathway 2-4.5 (SSP2-4.5) global warming scenario. Yield results show ARISE-SAI-1.5 leads to higher production for rainfed rice and wheat. We use 10 agroclimatic indices during the vegetative, reproductive, and ripening stages to evaluate these yield changes. ARISE-SAI-1.5 benefits rainfed wheat yields the most, compared to rice, due to its ability to prevent rising winter and spring temperatures while increasing wheat season precipitation. For rice, SSP2-4.5 leads to many more warm extremes than the control period during all three growth stages and may cause a delay in the monsoon. ARISE-SAI-1.5 largely preserves monsoon rainfall, improving yields for rainfed rice in most regions. Even without the use of SAI, adaptation strategies such as adjusting planting dates could offer partial relief under SSP2-4.5 if it is feasible to adjust established rice-wheat cropping systems.

Key Points

Climate intervention could benefit rainfed wheat more than irrigated crops in India, with regional differences for rainfed rice

Climate intervention could maintain temperatures in all growth stages and monsoon rainfall but would not stop winter precipitation changes

From a climatic standpoint, shifting planting dates may offer relief under global warming but might not be feasible in all cases

Plain Language Summary

Climate change is causing significant problems for farming worldwide, affecting food quantity, quality, and safety. To tackle this, some are exploring new strategies like stratospheric aerosol intervention (SAI). This study focuses on how SAI could impact rice and wheat farming in India, a country highly dependent on agriculture and vulnerable to climate change. Yield results from a crop model suggest that SAI could increase rice and wheat yields relative to climate change, particularly rainfed rice and wheat in particular locations, but the differences are not significant over most of India for irrigated crops. Using an experiment called ARISE-SAI-1.5, we evaluate 10 agroclimatic factors that can influence rice and wheat at different growth stages to determine the reasons for these yield changes. We find that SAI could potentially reduce some of the negative effects of global warming with a medium emission path, including reducing extreme heat days and retaining the summer monsoon. SAI benefits rainfed rice and wheat especially during their sensitive growth stages, which could be important in a future where maintaining irrigation systems may not be sustainable. Without SAI, while adaptation strategies like adjusting planting dates could help with mitigating the effects, uncertainties remain.

Source: AGU

[Renaud de RICHTER]

phys.org /news/2025-01-geoengineering-strategies-climate-positively-impact.html

Geoengineering strategies against climate change could positively impact agriculture

Aaron Sidder 16/01/2025

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Production differences (yield times crop area) in millions of tons per year between ARISE-SAI-1.5 and SSP2-4.5 from CLM5crop. Rice (a) and wheat (b) production are averaged over 2050–2069. Hatches indicate the difference between the two experiments is insignificant. Total Indian rice and wheat production time series (c). Shading represents the range corresponding to one standard deviation. Credit: Earth's Future (2025). DOI: 10.1029/2024EF005262

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 and colleagues 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 new work is published in the journal Earth's Future.

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.

More information: Nina Grant et al, Impacts on Indian Agriculture Due To Stratospheric Aerosol Intervention Using Agroclimatic Indices, Earth's Future (2025). DOI: 10.1029/2024EF005262

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