@article {5225,
	title = {Environment and paleoecology of a 12 ka mid-North American Younger Dryas forest chronicled in tree rings},
	journal = {Quaternary Research},
	volume = {70},
	year = {2008},
	month = {11/2008},
	pages = {433{\textendash}441},
	chapter = {433},
	abstract = {<p>Until now, availability of wood from the Younger Dryas abrupt cooling event (YDE) in N. America ca. 12.9 to 11.6 ka has been insufficient to develop high-resolution chronologies for refining our understanding of YDE conditions. Here we present a multi-proxy tree-ring chronology (ring widths, {\textquotedblleft}events{\textquotedblright} evidenced by microanatomy and macro features, stable isotopes) from a buried black spruce forest in the Great Lakes area (Liverpool East site), spanning 116\&nbsp;yr at ca. 12,000\&nbsp;cal yr BP. During this largely cold and wet period, the proxies convey a coherent and precise forest history including frost events, tilting, drowning and burial in estuarine sands as the Laurentide Ice Sheet deteriorated. In the middle of the period, a short mild interval appears to have launched the final and largest episode of tree recruitment. Ultimately the tops of the trees were sheared off after death, perhaps by wind-driven ice floes, culminating an interval of rising water and sediment deposition around the base of the trees. Although relative influences of the continental ice sheet and local effects from ancestral Lake Michigan are indeterminate, the tree-ring proxies provide important insight into environment and ecology of a N. American YDE boreal forest stand.</p>
},
	issn = {00335894},
	doi = {10.1016/j.yqres.2008.08.006},
	author = {Irina P. Panyushkina and Steven W. Leavitt and Todd A. Thompson and Allan F. Schneider and Todd Lange}
}
@article {5226,
	title = {Tree rings, δ13C and climate in Picea glauca growing near Churchill, subarctic Manitoba, Canada.  },
	journal = {Chemical Geology},
	volume = {252},
	year = {2008},
	month = {05/2007},
	pages = {1212{\textendash}1222},
	chapter = {88},
	abstract = {<p>How fast and how much climate can change has significant implications for concerns about future climate changes and their potential impacts on society. An abrupt climate change 8200 years ago (8.2\&nbsp;ka event) provides a test case to understand possible future climatic variability. Here, methane concentration (taken as an indicator for terrestrial hydrology) and nitrogen isotopes (Greenland temperature) in trapped air in a Greenland ice core (GISP2) are employed to scrutinize the evolution of the 8.2\&nbsp;ka event. The synchronous change in methane and nitrogen implies that the 8.2\&nbsp;ka event was a synchronous event (within {\textpm}4 years) at a hemispheric scale, as indicated by recent climate model results [Legrande, A. N., Schmidt, G. A., Shindell, D. T., Field, C. V., Miller, R. L., Koch, D. M., Faluvegi, G., Hoffmann, G., 2006. Consistent simulations of multiple proxy responses to an abrupt climate change event. Proceedings of the National Academy of Sciences 103, 837{\textendash}842]. The event began with a large-scale general cooling and drying around \~{}8175{\textpm}30 years BP (Before Present, where Present is 1950 AD). Greenland temperature cooled by 3.3{\textpm}1.1\&nbsp;{\textdegree}C (decadal average) in less than \~{}20 years, and atmospheric methane concentration decreased by \~{}80{\textpm}25\&nbsp;ppb over \~{}40 years, corresponding to a 15{\textpm}5\% emission reduction. Hemispheric scale cooling and drying, inferred from many paleoclimate proxies, likely contributed to this emission reduction. In central Greenland, the coldest period lasted for \~{}60 years, interrupted by a milder interval of a few decades, and temperature subsequently warmed in several steps over \~{}70 years. The total duration of the 8.2\&nbsp;ka event was roughly 150 years.</p>
},
	doi = {10.1016/j.chemgeo.2008.01.015},
	author = {Tardif, J.C. and Conciatori, F. and Leavitt, S.W.}
}
