Prolonged suppression of ecosystem carbon dioxide uptake after an anomalously warm year

Ecosystem CO2 uptake: Prolonged after-effects of an extremely warm year Earth's terrestrial ecosystems strongly modulate levels of CO2 in the atmosphere through seasonal changes in net plant productivity (CO2 absorbance) and soil microbial respiration (CO2 release). It has been known for decades that these processes respond to seasonal shifts in climate, especially temperature, resulting in the zig-zag form of the global CO2 curve, but the data necessary to quantify impacts of a single climate variable at interannual timescales have been lacking. A four-year study using intact tallgrass prairie ecosystems in controlled environment chambers (like the one on the cover, showing plant communities a few weeks after summer mowing) now provides some of the missing data. The results show that one anomalously warm year reduces net ecosystem CO2 exchange for that year and the year after. Carbon sequestration in ecosystems exposed to high temperatures for a year is a third of that in controls. These findings suggest that more frequent anomalously warm years, a possible consequence of rising anthropogenic CO2 levels, could lead to a sustained decrease in CO2 uptake by terrestrial ecosystems.