Ground surface temperature histories from the Last Glacial Cycle to present as inferred from borehole temperature data
Ground surface temperature histories from the Last Glacial Cycle to present as inferred from borehole temperature data
Previously Published Material: I presented parts of these findings at the AGU Fall Meeting in 2014.
Abstract ID#: 33862
English Abstract:
Twelve temperature-depth profiles (>1500 m) located in Eastern to Central Canada were studied to determine the ground surface temperature histories (GSTH) for the Last Glacial Cycle (LGC) and afterwards. The GSTHs were inferred by inversion. At three locations (Sudbury, Manitouwadge, and Thompson) with multiple boreholes, simultaneous inversion was used to illustrate regional trends. For all studied sites, the results indicate that ground surface temperatures throughout the LGC that range from -1.4-2.5°C, near the pressure melting point of ice. These ground surface temperatures are representative of the basal temperatures of the Laurentide Ice Sheet, which covered the region throughout the LGC. These temperatures allow for the possibility of basal flow and fast flowing ice streams, which have also been inferred from geomorphological data and are consistent with modeling efforts. Regional variations in basal temperatures are observed. A warming following the retreat of the ice sheet is noted at ~5-7.5 ka in all the GSTH reconstructions and is attributed to the Holocene Climatic Optimum. Only a portion of the sampled sites are suitable for studies of recent climate. These sites display signs of a cold period from 200-500 yrs BP, corresponding to the little ice age.