The climatic significance of rock glaciers

To obtain knowledge on the typical regional climate for rock glacier initiation and growth, a number of diagnostic geomorphological associations of normal glaciers and rock glaciers are analysed in selected regions of central west Greenland, north‐east Greenland and Antarctica. In these study areas, active rock glaciers and normal glaciers occur in proximity, and meteorological data are at hand. In general, the overall climate at active rock glaciers is not significantly different from that at the equilibrium line of normal glaciers nearby; the mean annual air temperature at rock glaciers usually is only slightly higher, if at all, than at nearby ELAs, and also the annual regional precipitation is only slightly lower than at nearby glaciers. In a regional temperature–precipitation space, active rock glaciers therefore tend to plot close to ELAs for modern glaciers, although with a tendency towards somewhat drier environments. The typical rock glacier climate is not exactly continental as has often been argued; it is rather a dry to moderate humid climate with cool summers. An important difference appears to be that while glaciers typically are situated at sites with a local, high accumulation of snow in relation to the input of talus, the opposite is true for rock glaciers. The different locations of glaciers and rock glaciers are thus mainly controlled by topoclimatic differences, rather than being a result of regional climatic differences. The observational data are still geographically limited and require both quality improvement and testing from other regions with active rock glaciers, but the topographic position and altitudinal distribution of rock glaciers probably contain unique climatic information, much the same as normal glaciers do. Therefore, relict rock glaciers represent a potentially important source of palaeoclimatic information. © 1998 John Wiley & Sons, Ltd.