Parallel climate and vegetation responses to the early Holocene collapse of the Laurentide Ice Sheet

• Main Authors: Bryan Shumana, Patrick Bartleinb, Nathaniel Logara, Paige Newbya, Thompson Webb Iiia
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2001
• Subjects: MAP; 1988; Bartlein et al; 1998; Webb et al; 1993; Hudson; Hudson Bay; Low Lake; Webb; Ice Sheet
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.580.8423; http://www.geo.brown.edu/georesearch/esh/QE/Publications/QSR2002/BShuman/ParallelPesponses/ParallelResponses.pdf

Parallel changes in lake-level and pollen data show that the rapid decline of the Laurentide Ice Sheet (LIS) between 10,000 and 8000 cal yr BP triggered a step-like change in North American climates: from an ice-sheet-and-insolation-dominated climate to a climate primarily controlled by insolation. Maps of the lake-level data from across eastern North America show a reorganization of climate patterns that the pollen data independently match. Raised lake-levels and expanded populations of moist-tolerant southern pines (Pinus) document that summer monsoons intensified in the southeastern United States between 9000 and 8000 cal yr BP. Simultaneously, low lake-levels and an eastward expansion of the prairie illustrate an increase in mid-continental aridity. After the Hudson Bay ice dome collapsed around 8200 cal yr BP, lake-levels rose in New England, as populations of mesic plant taxa, such as beech (Fagus) and hemlock (Tsuga), replaced those of dry-tolerant northern pines (Pinus). Available moisture increased there after a related century-scale period of colder-than-previous conditions around 8200 cal yr BP, which is also recorded in the pollen data. The comparison between pollen and lake-level data confirms that vegetations dynamics reflect climatic patterns on the millennial-scale.