Warming temperatures lead to reduced summer carbon sequestration in the US Corn Belt

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. Warming can reduce annual CO2 sequestration in cropland by inducing a negative impact on net CO2 uptake during the peak growing season, suggest twelve years of hourly CO2 measurements from a tall tower in the United States Corn Belt.

Automated summary

Research indicates that climate change has significant impacts on CO2 uptake in croplands and natural ecosystems in the Corn Belt region, with early crop growth stages experiencing an increase in net CO2 uptake, but peak growing seasons seeing a decrease. Future projections suggest that an increase in summer temperatures may result in a reduction of annual CO2 sequestration in the Corn Belt.