Warming temperatures lead to reduced summer carbon sequestration in the U.S. Corn Belt

Zhongjie Yu,John M Baker,Timothy J Griffis

doi:10.1038/s43247-021-00123-9

Abstract

The response of highly productive croplands at northern mid-latitudes to climate change is a primary source of uncertainty in the global carbon cycle, and a concern for future food production. We present a decadal time series (2007 to 2019) of hourly CO2 concentration measured at a very tall tower in the United States Corn Belt. Analyses of this record, with other long-term data in the region, reveal that warming has had a positive impact on net CO2 uptake during the early crop growth stage, but has reduced net CO2 uptake in both croplands and natural ecosystems during the peak growing season. Future increase in summer temperature is projected to reduce annual CO2 sequestration in the Corn Belt by 10–20%. These findings highlight the dynamic control of warming on cropland CO2 exchange and crop yields and challenge the paradigm that warming will continue to favor CO2 sequestration in northern mid-latitude ecosystems.

Highlights

The response of highly productive croplands at northern mid-latitudes to climate change is a primary source of uncertainty in the global carbon cycle, and a concern for future food production
Not all CO2 emitted from anthropogenic sources remains in the atmosphere; about one-fourth of the emissions are currently absorbed by the terrestrial biosphere[3], which has significantly slowed down global warming[4]
The terrestrial carbon (C) sink is driven by two large opposing ecosystem fluxes, i.e., photosynthesis and respiration, and is often indirectly estimated from the residuals of global C budgets

Summary

Introduction

The response of highly productive croplands at northern mid-latitudes to climate change is a primary source of uncertainty in the global carbon cycle, and a concern for future food production. A panel data model that combines the climate and NEE anomalies of the three tall tower sites was used to derive βT of NEE specific to croplands (i.e., corn and soybean) and natural terrestrial ecosystems (see Methods).

Results

Conclusion