Tropical Pacific Forcing of Hydroclimate in the Source Area of the Yellow River

The source area of the Yellow River (SAYR) contributes over one third of the basin discharge and bears disproportionate significance to water conservation in China. Hydroclimate changes in the SAYR, therefore, have potential far-reaching socioeconomic consequences. However, the major drivers of the SAYR hydroclimate remain poorly understood, largely due to limited hydroclimatic records. Here, we analyzed the organic, carbonate contents and stable isotopes of ¹⁴C-dated sediments from Ngoring Lake to reconstruct regional hydroclimate spanning the last ∼2,000 years. The results suggest that the SAYR experienced a near-millennium-long drying trend since the Medieval Warm Period, regardless of temperature changes and meltwater inputs. This trend, coherent with hydroclimate records from north China, is likely forced by a reduction in tropical Pacific zonal sea surface temperature gradient. Furthermore, our records have significant implications for other parts of the Tibetan Plateau that will likely develop similar hydroclimate conditions to the SAYR in the future.