TY - JOUR
T1 - Recent warming has resulted in smaller gains in net carbon uptake in northern high latitudes
AU - Zhu, Peng
AU - Zhuang, Qianlai
AU - Welp, Lisa
AU - Ciais, Philippe
AU - Heimann, Martin
AU - Peng, Bin
AU - Li, Wenyu
AU - Bernacchi, Carl
AU - Roedenbeck, Christian
AU - Keenan, Trevor F.
N1 - This research was supported by an NSF project (IIS-1027955) and a NASA LCLUC project grant (NNX09AI26G) to Q. Z. We acknowledge the Rosen High Performance Computing Center at Purdue for computing support. TFK was supported by the Director, Office of Science, Office of Biological and Environmental Research of the U.S. Department of Energy under Contract DE-AC02-05CH11231 as part of the RuBiSCo SFA. We thank comments from David Kicklighter and Dave McGuire. We also thank TRENDY team for providing the DGVM simulations and the researchers of NOAA/Earth System Research Laboratory for making their CO2 observation data available. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. government. The authors declare no competing financial interests.
Acknowledgments. This research was supported by an NSF project (IIS-1027955) and a NASA LCLUC project grant (NNX09AI26G) to Q. Z. We acknowledge the Rosen High Performance Computing Center at Purdue for computing support. TFK was supported by the Director, Office of Science, Office of Biological and Environmental Research of the U.S. Department of Energy under Contract DE-AC02-05CH11231 as part of the RuBiSCo SFA. We thank comments from David Kicklighter and Dave McGuire. We also thank TRENDY team for providing the DGVM simulations and the researchers of NOAA/Earth System Research Laboratory for making their CO2 observation data available. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. government. The authors declare no competing financial interests.
PY - 2019/9/1
Y1 - 2019/9/1
N2 - Carbon balance of terrestrial ecosystems in the northern high latitudes (NHL) is sensitive to climate change. It remains uncertain whether current regional carbon uptake capacity can be sustained under future warming. Here the atmospheric CO2 drawdown rate (CDR) between 1974 and 2014, defined as the CO2 decrease in ppm over the number of days in spring or summer, is estimated using atmospheric CO2 observations at Barrow (now known as Utqiaġvik), Alaska. We found that the sensitivity of CDR to interannual seasonal air temperature anomalies has trended toward less carbon uptake for a given amount of warming over this period. Changes in interannual temperature sensitivity of CDR suggest that relatively warm springs now result in less of a carbon uptake enhancement. Similarly, relatively warm summers now result in greater carbon release. These results generally agree with the sensitivity of net carbon exchange (NCE) estimated by atmospheric CO2 inversion. When NCE was aggregated over North America (NA) and Eurasia (EA), separately, the temperature sensitivity of NCE in NA has changed more than in EA. To explore potential mechanisms of this signal, we also examine trends in interannual variability of other climate variables (soil temperature and precipitation), satellite-derived gross primary production (GPP), and Trends in Net Land–Atmosphere Carbon Exchanges (TRENDY) model ensemble results. Our analysis suggests that the weakened spring sensitivity of CDR may be related to the slowdown in seasonal soil thawing rate, while the summer sensitivity change may be caused by the temporally coincident decrease in temperature sensitivity of photosynthesis. This study suggests that the current NHL carbon sink may become unsustainable as temperatures warm further. We also found that current carbon cycle models do not represent the decrease in temperature sensitivity of net carbon flux. We argue that current carbon–climate models misrepresent important aspect of the carbon–climate feedback and bias the estimation of warming influence on NHL carbon balance.
AB - Carbon balance of terrestrial ecosystems in the northern high latitudes (NHL) is sensitive to climate change. It remains uncertain whether current regional carbon uptake capacity can be sustained under future warming. Here the atmospheric CO2 drawdown rate (CDR) between 1974 and 2014, defined as the CO2 decrease in ppm over the number of days in spring or summer, is estimated using atmospheric CO2 observations at Barrow (now known as Utqiaġvik), Alaska. We found that the sensitivity of CDR to interannual seasonal air temperature anomalies has trended toward less carbon uptake for a given amount of warming over this period. Changes in interannual temperature sensitivity of CDR suggest that relatively warm springs now result in less of a carbon uptake enhancement. Similarly, relatively warm summers now result in greater carbon release. These results generally agree with the sensitivity of net carbon exchange (NCE) estimated by atmospheric CO2 inversion. When NCE was aggregated over North America (NA) and Eurasia (EA), separately, the temperature sensitivity of NCE in NA has changed more than in EA. To explore potential mechanisms of this signal, we also examine trends in interannual variability of other climate variables (soil temperature and precipitation), satellite-derived gross primary production (GPP), and Trends in Net Land–Atmosphere Carbon Exchanges (TRENDY) model ensemble results. Our analysis suggests that the weakened spring sensitivity of CDR may be related to the slowdown in seasonal soil thawing rate, while the summer sensitivity change may be caused by the temporally coincident decrease in temperature sensitivity of photosynthesis. This study suggests that the current NHL carbon sink may become unsustainable as temperatures warm further. We also found that current carbon cycle models do not represent the decrease in temperature sensitivity of net carbon flux. We argue that current carbon–climate models misrepresent important aspect of the carbon–climate feedback and bias the estimation of warming influence on NHL carbon balance.
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U2 - 10.1175/JCLI-D-18-0653.1
DO - 10.1175/JCLI-D-18-0653.1
M3 - Article
AN - SCOPUS:85074792239
SN - 0894-8755
VL - 32
SP - 5849
EP - 5863
JO - Journal of Climate
JF - Journal of Climate
IS - 18
ER -