The ‘Little Ice Age’ in the Himalaya: A review of glacier advance driven by Northern Hemisphere temperature change

Ann V Rowan

doi:10.1177/0959683616658530

Abstract

Northern Hemisphere cooling between 1400 and 1900 in the Common Era (CE) resulted in the expansion of glaciers during a period known as the ‘Little Ice Age’ (LIA). Early investigation of recent advances of Himalayan glaciers assumed that these events were synchronous with LIA advances identified in Europe, based on the appearance and position of moraines and without numerical age control. However, applications of Quaternary dating techniques such as terrestrial cosmogenic nuclide dating have allowed researchers to determine numerical ages for these young moraines and clarify when glacial maxima occurred. This paper reviews geochronological evidence for the last advance of glaciers in the Himalaya. The 66 ages younger than 2000 years (0–2000 CE) calculated from 138 samples collected from glacial landforms demonstrate that peak moraine building occurred between 1300 and 1600 CE, slightly earlier than the coldest period of Northern Hemisphere air temperatures. The timing of LIA advances varied spatially, likely influenced by variations in topography and meteorology across and along the mountain range. Palaeoclimate proxies indicate cooling air temperatures from 1300 CE leading to a southward shift in the Asian monsoon, increased Westerly winter precipitation and generally wetter conditions across the range around 1400 and 1800 CE. The last advance of glaciers in the Himalaya during a period of variable climate resulted from cold Northern Hemisphere air temperatures and was sustained by increased snowfall as atmospheric circulation reorganised in response to cooling during the LIA.

Highlights

The Himalaya contain the largest volume of glacier ice outside of the Arctic and Antarctic (Bolch et al, 2012)
Geochronological data from recent moraines formed by glaciers in the Himalaya indicate that these glaciers advanced during the lateHolocene around 900 Common Era (CE) (number of ages (n) = 41) and during the Little Ice Age (LIA) between 1300 and 1600 CE (n = 25) (Table 1)
The timing and duration of the Little Ice Age’ (LIA) in the Himalaya indicated by the distribution of moraine ages suggests that glacier maxima, inferred from periods of moraine building, commenced around 1300 CE, slightly earlier than the period of sustained Northern Hemisphere cooling between 1400 and 1700 CE

Summary

Introduction

The Himalaya contain the largest volume of glacier ice outside of the Arctic and Antarctic (Bolch et al, 2012). The recent Xarlungnama moraines formed by Rongbuk Glacier on the northern side of Mt Everest were dated to 400 ± 100 CE from TCN dating of three samples, which is broadly synchronous with the late-Holocene advance of glaciers in the Khumbu Himal (Owen et al, 2009). The central and western regions of Garhwal contain moraines from several glaciers including Gangotri Glacier that were assigned to the LIA using TCN dating These results were combined with those published for other nearby moraines to assign a regional age from seven samples of 1600 ± 100 CE for the LIA in the Central Himalaya, which was preceded by periods of advance at 500 ± 200 CE and. Historical records of glacier advance in the Karakoram indicate that glacial maxima may have occurred later here than for those glaciers further east, at around 1900–1920 CE (Kick, 1989)

Summary and interpretation of glacial geochronologies

Findings

Discussion

Conclusion