In the recent issue (December 19, 2018) of Nature Communications, Wang et al. reported that summer carbon uptake of the terrestrial ecosystem in the northern high latitudes has been significantly weakened by ongoing climate warming. In other words, warmer years were associated with lower ecosystem carbon uptake. This study, for the first time, reported the emerging negative impact of warming on summer carbon uptake in northern ecosystem.

Northern ecosystem plays an important role in global carbon uptake. Most studies of the northern hemisphere carbon cycle have focused on spring and autumn, but the climate change impact on summer carbon cycle remains unclear. Summer has the highest vegetation productivity, actively contributes to year-to-year variations in terrestrial carbon uptake and generally has the most favorable climatic conditions for carbon uptake. Wang et al. found that the summer carbon uptake is significantly negatively correlated with terrestrial temperature in ecosystem north of 50 degrees from 1979 to 2012. A refined analysis at the decadal scale reveals that this significant negative correlation only occurs in the later period (1996-2012). Further analysis based on remote-sensing datasets, arctic sea ice dataset, ecosystem modeling, and atmospheric transport modeling showed that this emerging negative temperature response is primarily due to the summer vegetation activities no longer positively responding to temperatures.

This study, together with recent studies on spring (Piao et al., 2107, Nature Climate Change, 7, 359-363) and autumn (Liu et al., 2018, Geophysical Research Letters, 45, 5562-5571) carbon cycle, imply a shift in the response of carbon uptake to warming from positive to negative in northern ecosystems.

This study is primarily supported by the Strategic Priority Research Program (A) of the Chinese Academy of Sciences: the Pan-Third Pole Environment Study for a Green Silk Road.

Citation: Wang T, Liu D, Piao S, Wang Y, Wang X, Guo H, Lian X, Burkhart J F, Ciais P, Huang M, Janssens I, Li Y, Liu Y, Peñuelas J, Peng S, Yang H, Yao Y, Yin Y, Zhao Y. Emerging negative impact of warming on summer carbon uptake in northern ecosystems. Nature Communications, 2018, 9(1): 5391.

The correlation between summer carbon take and temperature