A Global Carbon Cycle Problem Solved

Summary

Recently published research supported by the Biological and Environmental Research (BER) program has answered an important question about future changes in atmospheric CO₂ concentration. During their normal respiratory metabolism, plants globally release about 10 times as much CO₂ into the atmosphere each year as humans do by burning fossil fuels (plants also take up CO₂ during photosynthesis, so their respiration does not normally contribute to the ongoing atmospheric CO₂ increase). Any changes in normal global plant respiration might therefore affect atmospheric CO₂ levels. It has been thought for about a decade that rising CO₂ might inhibit plant respiration, and that this would act as an important negative feedback on atmospheric CO2 increase. But recent BER research, and other studies building on the BER-supported foundation, indicates that plant respiration is not directly affected by CO₂ concentration. Because of this, no negative feedback on CO₂ increase is expected from a slowing of plant respiration, and an important uncertainty concerning the future course of atmospheric CO₂ changes has been eliminated.