The Position of the Current Warm Period in the Context of the Past 22,000 Years of Summer Climate in China

Identifying the position of the Current Warm Period (CWP) in the context of the long-term climatic trend is vital for understanding the impact of human activity on climate change. Reconstructions of summer temperature and precipitation in eight subregions of China over the past 22,000 years show that the CWP summer temperature and precipitation in these subregions are all lower than in the Early to Middle Holocene. The timing of the Holocene temperature and precipitation peaks in northern China (including Northwest China, North China, and Northeast China) is mainly determined by orbital forcing. Greenhouse gas forcing and the land ice-sheet help to fine-tune the timing of the climate maxima. These findings show that the climate since the Last Glacial Maximum in northern China is more sensitive to nonanthropogenic external forcings, whereas the summer precipitation in Southwest China since the early 20th century is controlled more by anthropogenically forced changes. Plain Language Summary Reconstructions of past climate are essential for understanding current warming trends and reasons under the natural climate and anthropogenic forcings. We provide a climate reconstruction in China over the past 22,000 years using a novel method combining proxy data and model simulations. Our results show that the summer temperature and precipitation during the Current Warm Period in the eight subregions of China are both significantly lower than those in the Early and Middle Holocene, and the long-time summer temperature and precipitation variations are highly sensitive to orbital forcing. These results highlight the regional consistency in the climate response to external forcings.

Automated summary

The position of the Current Warm Period (CWP) in China's climate history over the past 22,000 years shows that summer temperature and precipitation during this period are lower than in the Early to Middle Holocene, with sensitivity to orbital forcing. While the climate in northern China is more sensitive to nonanthropogenic external forcings, anthropogenic forces have a stronger impact on summer precipitation in Southwest China since the early 20th century.