Tour-Bluets - Flux tower on a recently harvest boreal black spruce site with lowbush blueberry ground cover, Chibougamau, Quebec. Photo credit: Onil Bergeron image:36367:0::0

An international research team has recently published a study that investigated the carbon sink capacity of northern terrestrial ecosystems and found that the duration of the net carbon uptake period (CUP) has on average decreased due to warmer autumn temperatures. The study will be published in the January 3 in the journal Nature.

The carbon balance of terrestrial ecosystems is particularly sensitive to climatic changes in autumn and spring. The past twenty years has seen a rise in the autumn temperatures in northern latitudes of approximately 1.1 °C with spring temperatures up by 0.8 °C.

Autumn warming will cause most northern terrestrial ecosystems to lose carbon dioxide (CO2) and this offsets 90% of the increased carbon dioxide uptake during spring.

The researchers used computer modeling in order to integrate forest canopy measurements and remote satellite data. They found that while warm spring temperatures accelerate growth more than soil decomposition and enhance carbon uptake, autumn warming greatly increases soil decomposition and significantly reduces carbon uptake.

Lead author of the study, Dr. Shilong Piao from the LSCE, UMR CEA-CNRS, in France says “If warming in autumn occurs at a faster rate than in spring, the ability of northern ecosystems to sequester carbon will diminish in the future”.

Philippe Ciais also, a member of the research team and a scientist from the Global Carbon Project says “The potentially rapid decline in the future ability of northern terrestrial ecosystems to remove atmospheric carbon dioxide would make stabilization of atmospheric CO2 concentrations much harder than currently predicted”.

This study was supported by European Community-funded projects ENSEMBLES and CARBOEUROPE IP, and by the National Natural Science Foundation of China as well as by Fluxnet-Canada, which was supported by CFCAS, NSERC, BIOCAP, MSC and NRCan.