The title says it all, but not all of us necessarily realize what it is saying. I sure had to do a quick bit of Googling to decipher what terrestrial ecosystems were. But it wasn’t a hard find, once I realized it was simply a nice broad term for much of what grows in the ground, ie, agriculture, forestry, etc.
So once you’ve got that sorted out, the rest sort of falls in to place.
According to an international study which has been investigating the carbon sink capacity of these northern forests (I’m simplifying it for myself as much as you), the net carbon uptake period (CUP) has on average, decreased.
Once again I’m stuck with the feeling I’m going to have to explain what it is we’re on about here. But it’s not hard, trust me! We’ve all heard of carbon sinks, be they forests or oceans. Well it is the amount of carbon that they can imbibe that is at the heart of this little problem.
The research was published in the August 3rd edition of Nature, blaming the decrease on the increase in autumnal warming. Apparently, over the past two decades, autumn temperatures in the northern hemisphere have increased by about 1.1 °C, and spring temperatures by 0.8 °C.
Currently, many northern terrestrial ecosystems currently suffer a 90% CUP offset by the autumnal temperature increase. In other words, while the warm spring temperatures accelerate the amount of carbon that is taken in by the growth of plants, this benefit is eradicated by the autumn warmth, which increases soil decomposition.
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”.
Photo credit: Marc André Giasson via Global Carbon Project