Unprecedented recent summer warming and cross-sphere hydrological coupling in Asian Water Towers
Description
The Asian Water Towers play a crucial role in the hydrological cycle at sub-continent to hemispheric scales. Although temperature measurements show rapid warming in High Asia, the sensitivity and resilience of the large Water Towers are uncertain, because observational data are limited in space and time. Here, we use 814-year-long tree-ring width (TRW) and maximum latewood density (MXD) chronologies from Picea likiangensis from the eastern Tibetan Plateau to reconstruct June–September mean temperatures. Our reconstruction reveals the series warms by 1.5°C during the modern observation window (1970–2023), which is 0.5±0.4°C above the pre-industrial baseline (1210–1850), making 2024 the warmest summer in the past eight centuries. The winter runoff in the Brahmaputra, Indus and Salween headwaters amplifies this unprecedented warming due to atmosphere-cryosphere feedbacks in which enhanced meltwater, spring soil‑moisture persistence and reduced summer albedo accelerate regional warming. Detection and attribution analyses identify volcanic and solar forcing as the main drivers of natural, pre-industrial variability before 1850 CE, whereas anthropogenic forcing exceeds the 99 % detection threshold after 2020 CE.
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Institutions
- Yunnan University