November 20, 2020
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Climatic Impacts on Future 21st Century Global Agricultural Yields

Historical weather data informs projections of global yields of economically important crops

Rows of crops below a cloudy blue sky

Dramatic yearly weather changes have the potential to generate large economic effects in both individual countries and globally through trade. 

(Image by Tim Mossholder | Pexels.com)

The Science

Understanding the economic impacts of climatic changes on agriculture requires reliable projections of crop yields. However, the effects of changing weather patterns on crop yields have generally been estimated based on long-term trends at large spatial scales. Changes from year to year within individual countries may have greater economic impacts since slowly changing trends are easier to adapt to than floods or droughts that occur on shorter time scales. Researchers used historical data to isolate effects of weather patterns on yields, or “yield shocks”, for 12 major global food and cash crops. Estimating annual, country-level projections will allow future research to study the potential economic impacts of annual weather changes that are generally masked in long-term regional averages. 

The Impact

Most prior research on the effects of changing climate on crop yields has focused on long-term changes in yields at large spatial scales for a small number of crops. Better modeling the global implications of these changes requires more detailed projections, including country-specific annual yield shocks. This work models the effects of monthly weather patterns on 12 crops using historical data and projects annual weather-induced yield changes for these crops, by country, through 2100 under six future climate scenarios. They found that higher-level aggregations, such as continental or decadal averaging, mask the very large changes that can occur at annual country levels. These finer-scaled yield shocks can be used in a wide range of economic models to explore the local and global impacts of climate on agriculture. 

Summary

Many global economic models exist and have varying degrees of regional (country) and crop aggregation. A multi-model study comparing the economic effects of crop yield changes under multiple future climate scenarios that required consistent yield changes brought the lack of appropriately scaled data to the attention of researchers. To fill this void, they developed more comprehensive projections to suit their needs. These projections have broad potential applicability beyond that single study and will enable the comparison of the relative impacts on the agricultural system of long-term, but gradual, changes in climate conditions to weather changes that occur at sub-annual levels. 

PNNL Contact

Mohamad Hejazi, Pacific Northwest National Laboratory, Joint Global Change Research Institute, Mohamad.Hejazi@pnnl.gov 

Funding

JAE and STW received support for this research through the U.S. Department of Energy, Office of Science, as part of research in MultiSector Dynamics, Earth and Environmental System Modeling Program. ISW received support from the U.S. Department of Energy, Office of Science, Biological and Environmental Research Program, Earth and Environmental Systems Modeling, MultiSector Dynamics, Contract No. DE-SC0016162. GL, STW, and XZ received support from the U.S. Environmental Protection Agency, under Interagency Agreements DW8992395101 and DW08992459801. 

Published: November 20, 2020

Waldhoff ST, Sue Wing I, Edmonds JA, Leng G, Zhang X, “Estimating climate change impacts on crop yields for integrated assessment modeling.” Environmental Research Letters, (2020). 10.1088/1748-9326/abadcb. 

Research topics