Abstract
Holocene climatic, vegetational and environmental changes on the Ammassalik Island in SE Greenland (65.5 N and 37.5 W) have been studied in lake sediments and soil profiles. Based on the stratigraphy of sediments, geobiochemical characteristics, pollen and other biological proxies, a history of the land is outlined. The overall and continued climatic cooling during the Holocene basically seems to be orbitally controlled and due to both decreasing annual and summer insolations. The very early Holocene, concurrent with and following the final postglacial melting of glaciers in the landscape, appears to have experienced the warmest Holocene summer conditions, ice-free seas and limited snow covers. The climate situation seems to have been to a considerable extent based on internal regional meteorological processes and largely without strong and regular cyclonic impacts from lower latitudes. Generally decreasing insolation, a still colder landscape and near coastal sea, potentially further cooled by the negative albedo feedback from snow and ice, generally increase a gradient driven circulation of heat and moisture northwards in the western part of the North Atlantic. Counteracting this southerly influx of heat and moisture, will be the blocking effect of a snow and ice-covered region, resulting in decreasing precipitation and probably slightly increasing net radiation in landscapes. A framework and a climatic system are created to characterize the environmental changes of the latest 4-5 millennia. There has presumably been a continuous cooling trend interrupted by both spells and somewhat longer periods of renewed and stronger southerly influxes, relatively warmer conditions, higher precipitation and less sea ice.
| Originalsprog | Engelsk |
|---|---|
| Tidsskrift | Geografisk Tidsskrift |
| Vol/bind | 108 |
| Udgave nummer | 1 |
| Sider (fra-til) | 21-50 |
| ISSN | 0016-7223 |
| Status | Udgivet - 2008 |
Emneord
- Det Natur- og Biovidenskabelige Fakultet
- klima forandring
- vegetations forandringer
- Ammassalik
- Øst Grønland
FN’s Verdensmål
Dette resultat bidrager til følgende verdensmål
