Radiocarbon age-offsets in an arctic lake reveal the long-term response of permafrost carbon to climate change
Gaglioti, Benjamin V.
Mann, Daniel H.
Jones, Benjamin M.
Pohlman, John W.
Kunz, Michael L.
Wooller, Matthew J.
MetadataShow full item record
Continued warming of the Arctic may cause permafrost to thaw and speed the decomposition of large stores of soil organic carbon (OC), thereby accentuating global warming. However, it is unclear if recent warming has raised the current rates of permafrost OC release to anomalous levels or to what extent soil carbon release is sensitive to climate forcing. Here we use a time series of radiocarbon age-offsets (14C) between the bulk lake sediment and plant macrofossils deposited in an arctic lake as an archive for soil and permafrost OC release over the last 14,500 years. The lake traps and archives OC imported from the watershed and allows us to test whether prior warming events stimulated old carbon release and heightened age-offsets. Today, the age-offset (2 ka; thousand of calibrated years before A.D. 1950) and the depositional rate of ancient OC from the watershed into the lake are relatively low and similar to those during the Younger Dryas cold interval (occurring 12.9–11.7 ka). In contrast, age-offsets were higher (3.0–5.0 ka) when summer air temperatures were warmer than present during the Holocene Thermal Maximum (11.7–9.0 ka) and Bølling-Allerød periods (14.5–12.9 ka). During these warm times, permafrost thaw contributed to ancient OC depositional rates that were ~10 times greater than today. Although permafrost OC was vulnerable to climate warming in the past, we suggest surface soil organic horizons and peat are presently limiting summer thaw and carbon release. As a result, the temperature threshold to trigger widespread permafrost OC release is higher than during previous warming events.
Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Biogeosciences 119 (2014): 1630–1651, doi:10.1002/2014JG002688.
Showing items related by title, author, creator and subject.
Methane fluxes between terrestrial ecosystems and the atmosphere at northern high latitudes during the past century : a retrospective analysis with a process-based biogeochemistry model Zhuang, Qianlai; Melillo, Jerry M.; Kicklighter, David W.; Prinn, Ronald G.; McGuire, A. David; Steudler, Paul A.; Felzer, Benjamin S.; Hu, Shaomin (American Geophysical Union, 2008-08-18)We develop and use a new version of the Terrestrial Ecosystem Model (TEM) to study how rates of methane (CH4) emissions and consumption in high-latitude soils of the Northern Hemisphere have changed over the past century ...
Tank, Suzanne E.; Frey, Karen E.; Striegl, Robert G.; Raymond, Peter A.; Holmes, Robert M.; McClelland, James W.; Peterson, Bruce J. (American Geophysical Union, 2012-08-21)While much of the dissolved organic carbon (DOC) within rivers is destined for mineralization to CO2, a substantial fraction of riverine bicarbonate (HCO3−) flux represents a CO2 sink, as a result of weathering processes ...
Importance of recent shifts in soil thermal dynamics on growing season length, productivity, and carbon sequestration in terrestrial high-latitude ecosystems Euskirchen, E. S.; McGuire, A. David; Kicklighter, David W.; Zhuang, Qianlai; Clein, Joy S.; Dargaville, R. J.; Dye, D. G.; Kimball, John S.; McDonald, Kyle C.; Melillo, Jerry M.; Romanovsky, V. E.; Smith, N. V. (2005-10-07)In terrestrial high-latitude regions, observations indicate recent changes in snow cover, permafrost, and soil freeze-thaw transitions due to climate change. These modifications may result in temporal shifts in the growing ...