We present undercooled scree slope ecosystems as : -Possible refuges from climate changes for cold species in mountain regions -In-situ laboratories for temperature change research Undercooled scree slopes ecosystems are low-altitude blocky debris characterised by a reversible air circulation that split the scree area in ground thermal zones corresponding to a mosaic of adjacent ecosystems from island biotopes of boreo-alpine flora with dwarf trees on sporadic permafrost to the climacic forests. Numerous sites have been studied in Europe.