Rapidly changing high-latitude seasonality

Implications for the 21st century carbon cycle in Alaska

Bibliographic Data

ID15548340
AuthorsIan Shirley (0000-0002-2229-1414, Lawrence Berkeley National Laboratory, corresponding author), Z A Mekonnen (0000-0002-2647-0671, Lawrence Berkeley National Laboratory), R F Grant (0000-0002-8890-6231, University of Alberta), Baptiste Dafflon (0000-0001-9871-5650, Lawrence Berkeley National Laboratory), Susan S Hubbard (0000-0003-2966-5631, Lawrence Berkeley National Laboratory), W J Riley (0000-0002-4615-2304, Lawrence Berkeley National Laboratory)
Year2021
Volume17
Issue1
Pages014032-014032
Publication date2021-12-15
Peer ReviewedYes
Open AccessYes
TypeARTICLE
VenueEnvironmental Research Letters (JOURNAL)
Journal identifiersISSN: 1748-9326 • E-ISSN: 1748-9326
PublisherIOP Publishing (PUBLISHER • GB)
DOI10.1088/1748-9326/ac4362
OpenAlexW4200298778
LanguageEN
Citations received4
References cited75

Seasonal variations in high-latitude terrestrial carbon (C) fluxes are predominantly driven by air temperature and radiation. At present, high-latitude net C uptake is largest during the summer. Recent observations and modeling studies have demonstrated that ongoing and projected climate change will increase plant productivity, microbial respiration, and growing season lengths at high-latitudes, but impacts on high-latitude C cycle seasonality (and potential feedbacks to the climate system) remain uncertain. Here we use ecosys , a well-tested and process-rich mechanistic ecosystem model that we evaluate further in this study, to explore how climate warming under an RCP8.5 scenario will shift C cycle seasonality in Alaska throughout the 21st century. The model successfully reproduced recently reported large high-latitude C losses during the fall and winter and yet still predicts a high-latitude C sink, pointing to a resolution of the current conflict between process-model and observation-based estimates of high-latitude C balance. We find that warming will result in surprisingly large changes in net ecosystem exchange (NEE; defined as negative for uptake) seasonality, with spring net C uptake overtaking summer net C uptake by year 2100. This shift is driven by a factor of 3 relaxation of spring temperature limitation to plant productivity that results in earlier C uptake and a corresponding increase in magnitude of spring NEE from −19 to −144 gC m −2 season −1 by the end of the century. Although a similar relaxation of temperature limitation will occur in the fall, radiation limitation during those months will limit increases in C fixation. Additionally, warmer soil temperatures and increased carbon inputs from plants lead to combined fall and winter C losses (163 gC m −2 ) that are larger than summer net uptake (123 gC m −2 season −1 ) by year 2100. However, this increase in microbial activity leads to more rapid N cycling and increased plant N uptake during the fall and winter months that supports large increases in spring NPP. Due to the large increases in spring net C uptake, the high-latitude atmospheric C sink is projected to sustain throughout this century. Our analysis disentangles the effects of key environmental drivers of high-latitude seasonal C balances as climate changes over the 21st century

Atmospheric sciences · Biology · Carbon sink · Climate change · Climatology · Ecosystem · Geography · Growing season · Latitude · Primary production · Seasonality · Sink (geography · Atmospheric and Environmental Gas Dynamics · Climate change and permafrost · Climate variability and models · Environmental Science · Ecology

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