Projected Late 21st Century Warming Unprecedented in Northwest China in a Holocene Context

Abstract Northwest China is facing socio‐environmental challenges linked to ongoing climatic warming. However, a scarcity of regional paleorecord syntheses limits our understanding of natural long‐term climate variability in the region and hinders the contextualization of contemporary warming. Here, we present paleorecord syntheses for both summer and annual temperatures during the Holocene based on a range of lacustrine sediment records from northwest China, with consideration of chronological uncertainties within records. The syntheses show similar summer and annual temperature variations, including peak warmth at ∼9000 years BP, followed by a 2000‐year cooling trend, and stable temperatures thereafter. These variations may reflect inter‐seasonal impact of summer insolation forcing through climate feedbacks (e.g., Arctic sea‐ice cover) that are still not well represented in climate models. The early‐Holocene peak warmth was >1.0°C warmer than the 20th century mean warmth, but is expected to be exceeded during the 21st century even under a low emission scenario.