Global warming may not increase forest CO2 absorption capacity

An international study published in the journal Science challenges the hypothesis that global warming will increase the ability of forests to capture carbon dioxide (CO2). While rising temperatures extend the growing season for trees, researchers found that this does not necessarily lead to increased wood production or higher CO2 absorption.

By analyzing more than 50,000 conifer wood samples from over 100 forests across four continents, the research team—which included participants from the Estación Experimental del Zaidín (EEZ-CSIC) and the Instituto Pirenaico de Ecología (IPE-CSIC)—determined that the rate of new wood cell formation is the critical factor. This growth velocity is heavily dependent on water availability.

The findings suggest that the benefits of a longer growing season may be offset by drought and decreased water availability, which slow down the speed at which trees produce new wood cells. Consequently, the total annual wood production and the capacity of forest ecosystems to act as carbon sinks may not increase as previously expected.