@article {2487,
	title = {Methane emissions proportional to permafrost carbon thawed in Arctic lakes since the 1950s},
	journal = {Nature Geoscience},
	volume = {9},
	year = {2016},
	month = {Oct-08-2017},
	pages = {679 - 682},
	abstract = {Permafrost thaw exposes previously frozen soil organic matter to microbial decomposition. This process generates methane and carbon dioxide, and thereby fuels a positive feedback process that leads to further warming and thaw1. Despite widespread permafrost degradation during the past ~40 years2, 3, 4, the degree to which permafrost thaw may be contributing to a feedback between warming and thaw in recent decades is not well understood. Radiocarbon evidence of modern emissions of ancient permafrost carbon is also sparse5. Here we combine radiocarbon dating of lake bubble trace-gas methane (113 measurements) and soil organic carbon (289 measurements) for lakes in Alaska, Canada, Sweden and Siberia with numerical modelling of thaw and remote sensing of thermokarst shore expansion. Methane emissions from thermokarst areas of lakes that have expanded over the past 60 years were directly proportional to the mass of soil carbon inputs to the lakes from the erosion of thawing permafrost. Radiocarbon dating indicates that methane age from lakes is nearly identical to the age of permafrost soil carbon thawing around them. Based on this evidence of landscape-scale permafrost carbon feedback, we estimate that 0.2 to 2.5 Pg permafrost carbon was released as methane and carbon dioxide in thermokarst expansion zones of pan-Arctic lakes during the past 60 years.},
	keywords = {Carbon cycle, Climate change, Cryospheric science},
	issn = {1752-0894},
	doi = {10.1038/ngeo2795},
	url = {http://www.nature.com/doifinder/10.1038/ngeo2795},
	author = {Walter Anthony, Katey and Daanen, Ronald and Anthony, Peter and Schneider von Deimling, Thomas and Ping, Chien-Lu and Chanton, Jeffrey P. and Grosse, Guido}
}
@article {2530,
	title = {Cryosphere: Antarctic ice growth and retreat},
	journal = {Nature Geoscience},
	volume = {81008},
	year = {2015},
	month = {Jan-07-2016},
	pages = {585 - 586},
	keywords = {Cryospheric science, Palaeoclimate},
	issn = {1752-0894},
	doi = {10.1038/ngeo2494},
	url = {http://www.nature.com/doifinder/10.1038/ngeo2494},
	author = {Evans, Jeffrey}
}
@article {2544,
	title = {Silicon isotopes indicate enhanced carbon export efficiency in the North Atlantic during deglaciation},
	journal = {Nature Communications},
	volume = {5},
	year = {2014},
	month = {Nov-01-2015},
	abstract = {Today{\textquoteright}s Sargasso Sea is nutrient starved, except for episodic upwelling events caused by wind-driven winter mixing and eddies. Enhanced diatom opal burial in Sargasso Sea sediments indicates that silicic acid, a limiting nutrient today, may have been more available in subsurface waters during Heinrich Stadials, millennial-scale climate perturbations of the last glacial and deglaciation. Here we use the geochemistry of opal-forming organisms from different water depths to demonstrate changes in silicic acid supply and utilization during the most recent Heinrich Stadial. We suggest that during the early phase (17.5{\textendash}18 ka), wind-driven upwelling replenished silicic acid to the subsurface, resulting in low Si utilization. By 17 ka, stratification reduced the surface silicic acid supply leading to increased Si utilization efficiency. This abrupt shift in Si cycling would have contributed to high regional carbon export efficiency during the recent Heinrich Stadial, despite being a period of increasing atmospheric CO2.},
	keywords = {Biogeochemistry, Cryospheric science, Ocean sciences},
	doi = {10.1038/ncomms4107},
	url = {http://www.nature.com/doifinder/10.1038/ncomms4107},
	author = {Hendry, Katharine R. and Robinson, Laura F. and McManus, Jerry F. and Hays, James D.}
}
@article {2458,
	title = {Anthropogenic aerosols as a source of ancient dissolved organic matter in glaciers},
	journal = {Nature Geoscience},
	volume = {5},
	year = {2012},
	month = {Jul-02-2013},
	pages = {198 - 201},
	abstract = {Glacier-derived dissolved organic matter represents a quantitatively significant source of ancient, yet highly bioavailable carbon to downstream ecosystems1. This finding runs counter to logical perceptions of age{\textendash}reactivity relationships, in which the least reactive material withstands degradation the longest and is therefore the oldest2. The remnants of ancient peatlands and forests overrun by glaciers have been invoked as the source of this organic matter1, 3, 4. Here, we examine the radiocarbon age and chemical composition of dissolved organic matter in snow, glacier surface water, ice and glacier outflow samples from Alaska to determine the origin of the organic matter. Low levels of compounds derived from vascular plants indicate that the organic matter does not originate from forests or peatlands. Instead, we show that the organic matter on the surface of the glaciers is radiocarbon depleted, consistent with an anthropogenic aerosol source. Fluorescence spectrophotometry measurements reveal the presence of protein-like compounds of microbial or aerosol origin. In addition, ultrahigh-resolution mass spectrometry measurements document the presence of combustion products found in anthropogenic aerosols. Based on the presence of these compounds, we suggest that aerosols derived from fossil fuel burning are a source of pre-aged organic matter to glacier surfaces. Furthermore, we show that the molecular signature of the organic matter is conserved in snow, glacier water and outflow, suggesting that the anthropogenic carbon is exported relatively unchanged in glacier outflows.},
	keywords = {Atmospheric chemistry, Biogeochemistry, Cryospheric science},
	issn = {1752-0894},
	doi = {10.1038/ngeo1403},
	url = {http://www.nature.com/doifinder/10.1038/ngeo1403},
	author = {Stubbins, Aron and Hood, Eran and Raymond, Peter A. and Aiken, George R. and Sleighter, Rachel L. and Hernes, Peter J. and Butman, David and Hatcher, Patrick G. and Striegl, Robert G. and Schuster, Paul and Abdulla, Hussain A. N. and Vermilyea, Andrew W. and Scott, Durelle T. and Spencer, Robert G. M.}
}
@article {2488,
	title = {Geologic methane seeps along boundaries of Arctic permafrost thaw and melting glaciers},
	journal = {Nature Geoscience},
	volume = {5},
	year = {2012},
	month = {Aug-05-2013},
	pages = {419 - 426},
	abstract = {Methane, a potent greenhouse gas, accumulates in subsurface hydrocarbon reservoirs, such as coal beds and natural gas deposits. In the Arctic, permafrost and glaciers form a {\textquoteleft}cryosphere cap{\textquoteright} that traps gas leaking from these reservoirs, restricting flow to the atmosphere. With a carbon store of over 1,200 Pg, the Arctic geologic methane reservoir is large when compared with the global atmospheric methane pool of around 5 Pg. As such, the Earth{\textquoteright}s climate is sensitive to the escape of even a small fraction of this methane. Here, we document the release of 14C-depleted methane to the atmosphere from abundant gas seeps concentrated along boundaries of permafrost thaw and receding glaciers in Alaska and Greenland, using aerial and ground surface survey data and in situ measurements of methane isotopes and flux. We mapped over 150,000 seeps, which we identified as bubble-induced open holes in lake ice. These seeps were characterized by anomalously high methane fluxes, and in Alaska by ancient radiocarbon ages and stable isotope values that matched those of coal bed and thermogenic methane accumulations. Younger seeps in Greenland were associated with zones of ice-sheet retreat since the Little Ice Age. Our findings imply that in a warming climate, disintegration of permafrost, glaciers and parts of the polar ice sheets could facilitate the transient expulsion of 14C-depleted methane trapped by the cryosphere cap.},
	keywords = {Biogeochemistry, Cryospheric science},
	issn = {1752-0894},
	doi = {10.1038/ngeo1480},
	url = {http://www.nature.com/doifinder/10.1038/ngeo1480},
	author = {Walter Anthony, Katey M. and Anthony, Peter and Grosse, Guido and Chanton, Jeffrey}
}
