Recent Warming Has Resulted in Smaller Gains in Net Carbon Uptake in Northern High Latitudes
[1];
- Purdue Univ., West Lafayette, IN (United States)
- CEA CNRS UVSQ, Gif-sur-Yvette (France)
- Max Planck Inst. for Biogeochemistry, Jena (Germany)
- Univ. of Illinois at Urbana-Champaign, IL (United States)
- Tsinghua Univ., Beijing (China)
- Univ. of Illinois at Urbana-Champaign, IL (United States); U.S. Dept. of Agriculture-Agricultural Research Service, Urbana, IL (United States)
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
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 CO2drawdown rate (CDR) between 1974 and 2014, defined as the CO2decrease in ppm over the number of days in spring or summer, is estimated using atmospheric CO2observations at Barrow (now known as Utqiagvik), 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 CO2inversion. 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. Finally, 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.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- National Science Foundation (NSF); USDOE Office of Science (SC), Biological and Environmental Research (BER)
- Grant/Contract Number:
- AC02-05CH11231
- OSTI ID:
- 1581749
- Journal Information:
- Journal of Climate, Vol. 32, Issue 18; ISSN 0894-8755
- Publisher:
- American Meteorological SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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