The timing and duration of the Late Holocene climatic events from the Himalaya and other regions.

The timing and duration of the Late Holocene climatic events from the Himalaya and other regions.</p

Pollen assemblages of the major plant groups.

a. In the surface sediments, b. In the sub-surface sediments.</p

Ternary diagram showing the percentage of sand, silt and clay in the sub-surface samples.

Ternary diagram showing the percentage of sand, silt and clay in the sub-surface samples.</p

Summary diagram showing the results of different proxies and the climatic phases.

(χlf: magnetic susceptibility, WIP: Weathering Index of Parker, AP/NAP: arboreal pollen / non-arboreal pollen ratio, DACP: Dark Ages Cold Period, MCA/MCO: Medieval Climatic Anomaly/Medieval Climatic Optimum, LIA: Little Ice Age, CWP: Current Warm Period).</p

Tree-ring based precipitation and temperature records from adjoining areas.

a. Boreal spring precipitation reconstruction (MAM) from Kinnaur, extended back to AD 1030 (Yadava et al. 2016), b. Temperature reconstruction (MJJA) from Lahaul and Spiti, dating back to AD 940 (Yadav et al. 2011). The red and blue lines are low pass filter showing the fluctuations in timescale of 50 years and above. The vertical orange bar indicates the moist condition in late 11th century, which reflects the MCA/MCO and the vertical yellow bar represents the influence of the LIA.</p

Table showing the details of magnetic susceptibility in the trench samples.

Table showing the details of magnetic susceptibility in the trench samples.</p

Spreadsheet showing the respective percentages of spore-pollen taxa in the trench samples.

Spreadsheet showing the respective percentages of spore-pollen taxa in the trench samples.</p

Pollen spectra from the sub-surface sediments (trench) of the outwash plain, Hamtah Glacier.

Pollen spectra from the sub-surface sediments (trench) of the outwash plain, Hamtah Glacier.</p

Spreadsheet showing the respective percentages of spore-pollen taxa in the surface samples.

Spreadsheet showing the respective percentages of spore-pollen taxa in the surface samples.</p

¹⁴C AMS dates of the four trench samples.

Palynological analysis of surface soil and sub-surface sediments from the outwash plain of Hamtah Glacier, Lahaul-Spiti, India, has brought out the vegetation and climatic changes in the area during the last 1580 years. The arboreal and non-arboreal pollen ratio (AP/NAP) has been used to demarcate the different vegetation and climatic zones, complemented by the frequencies of the broad-leaved taxa. Lower values of thermophilous, broad-leaved arboreal taxa, indicate that the region experienced cold-arid conditions between 1580 and 1330 yr BP (AD 370–620); which can be related to the Dark Ages Cold Period (DACP). Thereafter, between 1330 and 950 yr BP (AD 620–1000), a rejuvenation of the broad-leaved elements reflects the initiation of a comparatively warm and moist phase, marking the Medieval Climatic Anomaly (MCA) in the region. The warm-moist phase was, however, short-lived, and from 950 yr BP to the Present (AD 1000 onwards), the region saw a return to cold-arid conditions, as evidenced by a sharp fall in the AP/NAP ratio. This cold-arid phase was, nevertheless, punctuated by a warm-moist period during 790 to 680 yr BP (AD 1160–1270), which marks the terminal phase of the MCA. After the termination of the MCA, the Little Ice Age (LIA) is well-marked in the area. The culmination of the long cold-arid regime is characterized by warmer conditions over the last 160 years, which is the manifestation of the Current Warm Period (CWP). Magnetic susceptibility (χlf) and sediment geochemistry (Weathering Index of Parker) were also attempted to have a multi-proxy approach, and show a general compatibility with the palynological data. The palaeoclimatic evidences suggest shorter warm periods and extended colder phases during the last 1580 years; in this high-altitude, cold-desert, Trans Himalayan region.</div