Comparing near-shore marine and terrestrial paleoclimate reconstructions
If we hope to make global maps of the climate conditions for time periods in the past and to compare these to global climate model simulations, we need to reconcile our estimates from the marine and terrestrial deposits. This study is a step in that direction. An abstract from a recent paper is seen below.
Comparison of marine and terrestrial Holocene climatic reconstructions from northeastern North America by Sawada, M., Gajewski, K., de Vernal, A., and Richard, P. (1999). The Holocene , 9 : 267-277.
Quantitative climate reconstructions based on marine dinocysts and terrestrial pollen sequences are consistent through the Holocene in northeastern North America. Principal components analysis (PCA) indicates a large-scale climate signal in the dinocysts and pollen. The combined and separate analyses of marine and nearby terrestrial pollen sequences from Hudson Bay, Labrador and the St. Lawrence estuary differentiate tundra, boreal forest and deciduous forest assemblages in time and space. These analyses indicate that the marine pollen reflects vegetation changes of the regional terrestrial environment and allows direct correlations between the marine and terrestrial stratigraphies. Sea surface temperatures from dinocysts and terrestrial air temperatures from pollen, estimated by the method of modern analogs show that the three regions had differing climate histories associated with their location with respect to deglaciation and air mass boundaries. High frequency changes in the St. Lawrence estuary and Gulf and a cooling reconstructed for the period prior to 8000 yr BP are less reliable due to the larger values of the dissimilarity coefficients. Prior to 6000 yr BP, cool temperatures reconstructed along the Labrador margins, both in the marine and terrestrial environments, are in agreement with climate simulations indicating the persistence of an anticyclone over the Québec-Labrador ice sheet. In both Labrador and northwestern Québec, a late Holocene cooling affects sites in the forest-tundra, but is not evident in boreal forest sites, suggesting movements in the polar front.
Keywords: paleoclimate, method of modern analogs, Labrador, Québec, pollen, dinocyst, principal components analysis
Figure Caption : Map showing all sites used in PCA. See table 1 for references.
Figure Caption : Climate reconstructions for terrestrial and marine cores in the St. Lawrence region. Fitted curve as in Fig 6.
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