Vegetation and climate in upper Spiti region, Himachal Pradesh during late Holocene.

Pollen analysis of Sitikher bog near Kunzum Pass (Himachal Pradesh) indicates that between 2300 and 1500 yr BP, cold and dry climate prevailed in the upper Spiti region and glaciers advanced towards the lower elevations. Between 1500 and 900 yr BP the climate changed to warm and moist, which resulted in the retreat of glaciers and shift of tree line towards the higher elevations. From 900 yr BP onwards the mountain glaciers/tree line descended with the return of cold climate which continues until the present time.