Extreme Dry-Heat Climate Impacts on Greenhouse Gas Emission Intensity in Wheat Production: Insights and Mitigation Strategies.

Extreme dry-heat (EDH) climate poses significant challenges to global food production and exacerbates greenhouse gas (GHG) emissions, impeding efforts to mitigate agricultural climate impacts. However, the concurrent effects of long-term EDH climate and mitigation strategies on cropland productivity and GHG emissions remain poorly understood. Here, we integrated field observations, agroecosystem model outputs, and nursery data to examine how environmental factors and management practices influence wheat GHG emission intensity across the U.S. over the past six decades. Our findings indicate an overall increase in U.S. wheat production over the past 60 years, despite fluctuations in planted areas that have led to declines in production after 1990. The decline in GHG emissions from winter wheat after 1990 corresponds to fluctuations in planting areas, whereas emissions from spring wheat have continued to rise. Climate change and nitrogen fertilizer application have emerged as the primary drivers of these trends. EDH climates have intensified emissions intensity in over 80% of wheat-growing regions under current agricultural management practices. Specifically, the dry-heat sensitivity of emission intensity for spring wheat increased by 130% from 1960 to 2018, while for winter wheat, it surged several-fold after 2008. To address these challenges, we propose environment-specific tillage strategies to significantly reduce the dry-heat sensitivity of GHG emission intensity under local conditions. These strategies identify regionally optimal tillage schemes (including no-tillage and conventional tillage) to mitigate the adverse impacts of EDH climates. The implementation of these strategies in selected wheat-producing regions reduced dry-heat sensitivity by 9.8% (5.8%-17.7%) for spring wheat and 13.3% (8.0%-20.9%) for winter wheat emissions intensity. These findings underscore the critical need for targeted management approaches to alleviate the escalating indirect impacts of EDH climates. Such strategies are crucial for shaping agricultural and environmental policies aimed at achieving high-yield and low-emission targets in a warming world.