Tree rings reveal hydroclimatic fingerprints of the Pacific Decadal Oscillation on the Tibetan Plateau

Central Himalayan tree-ring isotopes reveal increasing regional heterogeneity and enhancement in ice mass loss since the 1960s

“…Hydroclimatic studies from the monsoon-dominated Himalaya-Tibet orogen indicate a pervasive but temporally unstable coherence. Low-frequency coherence between tree-ring δ 18 O-derived regional hydroclimatic reconstructions and the above indices of atmosphereocean interaction appears to have strengthened in recent decades (Sano et al, 2012(Sano et al, , 2013(Sano et al, , 2017Singh et al, 2019;Hochreuther et al, 2016;Lyu et al, 2019). In accordance, our results too show a strong correlation at a multi-decadal timescale between tree-ring δ 18 O chronologies available from the WCH and the above indices (Fig.…”

“…Wavelet coherence analyses of reconstructed GMB with annual Niño 4 SST revealed an unstable common frequency composition in the different series over time, indicating a wobbly linkage with the change in SSTs (Fig. S5), as observed in previous studies of regional hydroclimates (Sano et al, 2012(Sano et al, , 2013(Sano et al, , 2017Singh et al, 2019;Hochreuther et al, 2016;Lyu et al, 2019). Similarly, we noted a weak correlation with other indices (Fig.…”

“…This mechanism may explain the decline in precipitation frequency, snowfall, and total precipitation amount from the westerlies since the mid-20th century (Hunt et al, 2019;Shekhar et al, 2010;Kumar et al, 2015;Khan et al, 2019). Tree-ring δ 18 O records from Bhutan to the southeast TP (Sano et al, 2013;Hochreuther et al, 2016;Lyu et al, 2019) show more or less unaltered conditions during the 20th century. Thus, weakening of the BoB branch as indicated in some studies (Roxy et al, 2017) needs reappraisal.…”

“…The influence of the ISM declines towards the northwest Himalaya, and the westerlies progressively become dominant. Towards the eastern Himalaya, the influence of the Arabian Sea branch of the ISM declines, and the Bay of Bengal branch dominantly regulates the climate, besides an influence of the East Asian monsoon (Benn and Owen, 1998;Bookhagen and Burbank, 2010;Hochreuther et al, 2016;Liu et al, 2014;Lyu et al, 2019;Mölg et al, 2014;Sano et al, 2017;Yang et al, 2008;Yao et al, 2012). Monsoon-influenced glaciers, particularly those in the transitional climatic zone (such as the western region of the central Himalaya), are more sensitive to climate warming than winter-accumulation type glaciers Sakai and Fujita, 2017).…”

Central Himalayan tree-ring isotopes reveal increasing regional heterogeneity and enhancement in ice-mass loss since the 1960s

“…The influence of the ISM declines towards the northwest Himalaya, and the westerlies progressively becomes dominant. Towards the eastern Himalaya, the influence of the Arabian Sea (AS) branch of the ISM declines, and the Bay of Bengal branch (BoB) dominantly regulates the climate, besides having influence of the East Asian monsoon (Benn and Owen, 1998;Bookhagen and Burbank, 2010;Hochreuther et al, 2016;Liu et al, 2014;Lyu et al, 2019;Mölg et al, 2014;Sano et al, 2017;Yang et al, 2008;Yao et al, 2012). Monsoon-influenced glaciers, particularly those in the transitional climatic zone (such as western region of the central Himalaya) are particularly sensitive to climate warming than winter-accumulation type glaciers (Kargel et al, 2011;Sakai and Fujita, 2017).…”