@article { ISI:000342993200010,
	title = {Radiocarbon age-offsets in an arctic lake reveal the long-term response of permafrost carbon to climate change},
	journal = {JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES},
	volume = {119},
	number = {{8}},
	year = {2014},
	month = {AUG},
	pages = {1630-1651},
	type = {Article},
	abstract = {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 (C-14) 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 (2ka; 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 12.9-11.7ka). In contrast, age-offsets were higher (3.0-5.0ka) when summer air temperatures were warmer than present during the Holocene Thermal Maximum (11.7-9.0ka) and BOlling-AllerOd periods (14.5-12.9ka). During these warm times, permafrost thaw contributed to ancient OC depositional rates that were similar to 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.},
	keywords = {carbon cycling, lake sediment, paleoclimatology, permafrost, radiocarbon, Younger Dryas},
	issn = {2169-8953},
	doi = {10.1002/2014JG002688},
	author = {Gaglioti, Benjamin V. and Mann, Daniel H. and Jones, Benjamin M. and Pohlman, John W. and Kunz, Michael L. and Wooller, Matthew J.}
}
@article {190,
	title = {Methane hydrate-bearing seeps as a source of aged dissolved organic carbon to the oceans},
	journal = {Nature Geoscience},
	volume = {4},
	year = {2011},
	note = {id: 2030; PT: J; UT: WOS:000285498600015},
	pages = {37-41},
	abstract = {Marine sediments contain about 500-10,000 Gt of methane carbon(1-3), primarily in gas hydrate. This reservoir is comparable in size to the amount of organic carbon in land biota, terrestrial soils, the atmosphere and sea water combined(1,4), but it releases relatively little methane to the ocean and atmosphere(5). Sedimentary microbes convert most of the dissolved methane to carbon dioxide(6,7). Here we show that a significant additional product associated with microbial methane consumption is methane-derived dissolved organic carbon. We use Delta(14)C and delta(13)C measurements and isotopic mass-balance calculations to evaluate the contribution of methane-derived carbon to seawater dissolved organic carbon overlying gas hydrate-bearing seeps in the northeastern Pacific Ocean. We show that carbon derived from fossil methane accounts for up to 28\% of the dissolved organic carbon. This methane-derived material is much older, and more depleted in (13)C, than background dissolved organic carbon. We suggest that fossil methane-derived carbon may contribute significantly to the estimated 4,000-6,000 year age of dissolved organic carbon in the deep ocean(8), and provide reduced organic matter and energy to deep-ocean microbial communities.},
	issn = {1752-0894},
	doi = {10.1038/NGEO1016},
	author = {Pohlman, John W. and Bauer, James E. and Waite, William F. and Osburn, Christopher L. and Chapman, N. Ross}
}
