Geothermal inversion of Canadian Arctic ground temperatures and effect of permafrost aggradation at emergent shorelines

Abstract

We apply traditional geothermal spectrum inversion to precision temperature logs and thermal conductivity from 10 wells in the Canadian Arctic Archipelago (75° to 81°N). Sites lie beyond the Holocene marine limit, and no effect of deep permafrost dynamics is expected. Ground surface temperature (GST) changes correlate with the Little Ice Age and Little Climatic Optimum with average amplitudes relative to 1980 of −2.7 K and +1.6 K, respectively. Results correlate broadly with similar reconstructions for this area and Greenland ice cap holes GRIP and Dye‐3 to the southeast. An offshore site in 244 m water yields a Little Ice Age seabed temperature amplitude of −0.7 K, suggesting a moderated climate impact on regional ocean temperatures. Nearshore boreholes where permafrost is aggrading owing to glacioisostatic emergence are excluded; we demonstrate that traditional inversion codes without latent heat of phase change predict the magnitude of the emergence signal but a timing far too recent.