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Ellesmere Island, Canada. The ecology (limnology) of this small Arctic lake is has recently undergone profound change, as recorded by the diatom fossils observed in the sediments. Photo credit: Marianne Douglas.

Photomicrograph of pre-1850 Elison Lake sediment sample, Ellesmere Island, Canada. Shows scarcity of diatoms before the post-1850 Arctic warming event. Photo credit: Marianne Douglas.

Photomicrograph of present-day Elison Lake sediment sample, Ellesmere Island, Canada. Shows abundance of diatoms that characterizes sediment samples younger than 1850. Photo credit: Marianne Douglas.
Figure 4 illustrates lake sediment records from climatically and limnologically contrasting regions of Ellesmere Island (M.S.V. Douglas, J.P. Smol, W. Blake Jr., Science 226, 416 (1994); N.C. Doubleday, M.S.V. Douglas and J.P. Smol, The Science of the Total Environment 160/161, 661 (1995); A.P. Wolfe, in Climate Change in the High Arctic, M. Garneau, Ed. (Geological Survey of Canada Memoir) in press., The inflection between unsupported and background (in situ production) 210Pb activities in the Col Pond and Elison Lake cores indicates apporximately 1850 AD, which coincides with the onset of major diatom shifts in these cores. The Solstice Lake chronology is based on a linear interpolation between calendar-age-calibrated radiocarbon ages. This model place the major diatom changes within the last 120 years. The Lower Dumbell Lake core is without a radiometric chronology, but also suggests that substantial floristic change occured within the last 100 to 150 years.), each showing abrupt changes in the composition of fossil diatom assemblages deposited within approximately the last 150 years. These biostratigraphic changes are unrelated to differential silica preservation and represent the greatest floristic shifts of the middle to late Holocene. Taxonomic diversification with greater representations of littoral and periphytic taxa (A-C), increased diatom algal biomass (C), and recent diatom (re)colonization (D) are all consistent with the abrupt 19th- to 20th-century shift towards longer summer growing seasons, reduced lake-ice severity, and greater habitat availability. The limnological consequences of the 19th to 20th century warming appear to be unprecedented in the context of pre-18th century natural variability. To access the diatom data used to construct this figure, please click here.
Site elevations
Elison Lake 17 m asl

Col Pond 135 m asl

Lower Dumbell Lake 83 m asl

Solstice Lake 305 m asl

Some characteristics of the data
Coring, sediment processing and diatom taxonomy
Some important points to consider when viewing the data

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