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Keenan’s Study Suggest Accumulation of CO2 in the Atmosphere has Plateaued2 min read

by Maryann Villavert

Climate and Ecosystem Sciences Division Climate Modeling Program In The Press Publication
iStock Aerial view of the Amazon rainforest, Brazil

Aerial view of the Amazon rainforest, Brazil—a tropical and high-latitude ecosystem (image from iStock).

A paper in Nature Communications, published online today (November 8), suggests that the rate at which CO2 is accumulating in the atmosphere has plateaued in recent years because Earth’s vegetation is grabbing more carbon from the air than in previous decades. These new finding by Trevor Keenan et al. “…highlights the need to identify and protect ecosystems where the carbon sink is growing rapidly,” says Keenan (research scientist, Climate & Ecosystem Sciences Division).

Trevor Keenan portrait

Trevor Keenan

The scientists used ten “global dynamic vegetation models” that predict how the terrestrial carbon cycle changes over time, as well as a model that incorporates satellite measurements of vegetation cover and plant activity to predict global photosynthesis and respiration rates. Model validations were done by comparing its results with data from AmeriFlux (managed by Lawrence Berkeley National Laboratory for the Department of Energy) and FLUXNET. Model projections were generated using different scenarios of atmospheric CO2 level, temperature, soil moisture, and other processes. This enabled the researchers to evaluate the impacts of these processes on the planet’s terrestrial carbon cycle. Models showed rising CO2 levels as having the biggest impact on photosynthesis and plant respiration. The result was a boost in terrestrial carbon uptake, particularly in tropical and high-latitude ecosystems. The scientists concluded this carbon uptake put the brakes on the growth rate of atmospheric CO2 between 2002 and 2014.

Read more about the “Study: Carbon-Hungry Plants Impede Growth Rate of Atmospheric CO2” from the Berkeley Lab News Center (November 8, 2016).

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