Changing mountain permafrost from the 1970s to today – comparing two examples from Niwot Ridge, Colorado Front Range, USA

Climatic signals in geomorphological systems

Auteur(s) et Affiliation(s)

LEOPOLD, M.

Univ. of Western Australia, School of Earth and Environment, Crawley, Australie

VÖLKEL, J.

Technical Univ. München, Dept of Ecology and Ecosystem Management, Geomorphology and Soil Science, Freising, Allemagne

DETHIER, D.P.

Williams College, Dept. of Geosciences, Williamstown, Etats-Unis

WILLIAMS, M.W.

Univ. of Colorado, Dept. of Geography and Inst. of Arctic and Alpine Research (INSTAAR), Boulder, Etats-Unis

Description :
The study site Niwot Ridge, situated at ~3600 m a.s.l. in the Front Range of the Rocky Mountains, Colorado, USA, offers permafrost distribution data from the early 1970s. The AA. used 4 different approaches (air photographs and survey stakes; temperature profiles; electric resistivity profiles; a simple 1 D-heat flow model) to evaluate and compare the old data with recent conditions and to discuss consequences in how the old data should be considered. The results highlight that at present, on south facing slopes, permafrost neither exists at 2 m depth on wet sites nor at 4 m depth on dry sites as suggested during the 1970s. The modeling approach further suggests that, except on wet gelifluction lobes, it is likely that permafrost was not present at 3600 m during 1970, if so, permafrost degradation on south facing slopes on Niwot Ridge was not driven by recent climate change. However, north-facing slopes do cover permafrost, and certainly did in the 1970s, they are most probably affected by climate warming as already documented by a changing hydro-chemical signal in nearby streams.

Type de document :
Article de monographie

Source :
Zeitschrift für Geomorphologie, issn : 0372-8854, 2014, vol. 58, n°. 1, Supl., p. 137-157, nombre de pages : 21, Références bibliographiques : 39 ref.

Date :
2014

Editeur :
Pays édition : Allemagne, Stuttgart, Gebruder Borntraeger

Langue :
Anglais