Past Climate Variability and Change in the Arctic and at High Latitudes

A
Past Climate Variability and Change in the Arctic and at High Latitudes
Figure 3.26. A) Greenland without ice for the last time? Dark green = boreal forest; light green =
deciduous forest; brown = tundra and alpine heaths; white = ice caps. The north-south temperature gradient
is constructed from a comparison of North Greenland and northwest European temperatures, using
standard lapse rate; distribution of precipitation assumed to retain the Holocene pattern. Topographical
base, from model by Letreguilly et al. (1991) of Greenland’s sub-ice topography after isostatic recovery.
B) Upper part of the Kap København Formation, North Greenland. The sand was deposited in an estuary
about 2.4 Ma; it contains abundant well-preserved leaves, seeds, twigs, and insect remains. (Figure and
photograph by S.V. Funder.)
of the Milankovitch variations during millions
of years (e.g., Berger et al., 1992). As discussed
above, uncertainties in estimation of atmospheric
CO 2 concentration, ocean heat transport,
and perhaps other factors at the time of the kAp
københAvn Formation are sufficiently large to
preclude strong conclusions about the causes of
the unusual warmth.
Potentially correlative records of warm interglacial
conditions are found in deposits on
coastal plains along the northern and western
B
shores of AlASkA. High sea levels during
interglaciations repeatedly flooded the berinG
StrAit, and they rapidly modified the configuration
of the coastlines, altered regional continentality
(isolation from the moderating influence
of the sea), and reinvigorated the exchange of
water masses between the North Pacific, Arctic,
and north AtlAntic oceAnS. Since the first submergence
of the berinG StrAit about 5.5–5 Ma
(Marincovich and Gladenkov, 2001), this
marine gateway has allowed relatively warm
High sea levels during
interglaciations
repeatedly flooded
the Bering Strait, and
they rapidly modified
the configuration of
the coastlines.
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