Thermokarst ponds as indicators of the former distribution of palsas in Finnish lapland

Thermokarst ponds resulting from thawing of palsas were mapped in a 95 km-long transect area in northern Finland. The spatial distribution of thermokarst was related to palsa distribution and to geographical variables using GIS techniques and multivariate spatial modelling. In our 3370 km(2) study area, the former distribution of palsas was about three times larger than the present one. This indicates that the formation and thawing of permafrost are not in balance; palsas are collapsing and melting more often than palsas are forming. Copyright (C) 2003 John Wiley Sons, Ltd.