Central Himalayan tree-ring density network reveals warm-season temperature variability back to 1775 CE

Abstract

Although recognized as Asia’s “Water Tower”, our understanding of past natural and recent anthropogenic enforced climate change is limited for much of the Himalayas. The main contributing factors for that are sparse and short meteorological observations, seasonally restricted and often imprecise proxy archives, and spatially heterogeneous and temporally unstable climate dynamics. Here we present a network of five maximum latewood density (MXD) chronologies from 135 living fir (Abies spectabilis) trees from sites near the upper treeline between 3220 and 3750 m a.s.l. in Nepal. Individual series were processed to preserve interannual, decadal, and centennial-scale variability. The resulting composite chronology was calibrated against April–September (AMJJAS) temperatures over the period 1951–2022 CE (r_s = 0.64; p < 0.001), enabling the first MXD network-based temperature reconstruction for the Central Himalayas. Despite the relatively short reconstruction coverage (1775–2022 CE), it by far surpasses any regional instrumental record and explains more than 40% of AMJJAS temperature variance over much of the Asian Water Tower during the calibration period (1951 − 2022 CE). This novel high-resolution insight reveals the coldest period following the 1815 Tambora eruption, with the strongest summer cooling found in 1817 rather than 1816 CE (− 1.6 °C relative to 1951–1980 CE). Our results demonstrate that MXD is a robust proxy for warm-season temperatures in monsoon-influenced regions, capturing a strong and widespread signal across South and Southeast Asia, and holds great potential for further spatio-temporal extension of the MXD network.

Keywords

Dendroclimatology / Temperature reconstruction / Temperature variability / Central Himalaya

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