Tree rings suggest an unprecedented weakening of seasonal temperature difference in East Asia
IMAGE: THE RECONSTRUCTED SEASONAL TEMPERATURE DIFFERENCE (BLACK LINE) AND ITS TRENDS (RED LINES) FOR EAST ASIA AS WELL AS THE TIME OF ONSET OF SUSTAINED WEAKENING TREND (BLUE VERTICAL LINE) AND THE TIME OF CLIMATE EMERGENCE (GREEN VERTICAL LINE) view more
CREDIT: ©SCIENCE CHINA PRESS
The research was jointly led by Prof. Jianglin Wang (Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, China) and Prof. Bao Yang (Nanjing University, China) with coauthors Dr. Zhiyuan Wang (Zhejiang Normal University, China), Prof. Jürg Luterbacher (World Meteorological Organization, Switzerland), Prof. Fredrik Charpentier Ljungqvist (Stockholm University, Sweden).
Seasonal temperature difference (summer-minus-winter), also known as temperature annual cycle or temperature seasonality, is a dominant feature of the Earth’s climate system outside the tropics with important impacts on social and biological systems.
By carefully distinguishing winter or summer temperature sensitive tree ring data, the authors provide new insight into summer and winter temperatures as well as the seasonal difference of the past, beyond the limited historical observational data. They also compared the seasonal temperature reconstructions with climate model simulations.
The results show a sustained warming trend in East Asia largely caused by anthropogenic greenhouse gas forcing firstly found in summer as early as the 1830s. In winter, there is a delay of nearly three decades than that in summer. The authors also found evidence of a more significant cooling in summer than winter caused by tropical volcanic eruptions.
In contrast, the reconstructed seasonal temperature difference of East Asia shows a sustained weakening trend as early as the 1870s. The results suggest that anthropogenic radiative forcing had already driven the current seasonal difference outside the range of the natural climate variability of the pre-industrial times.
They found that climate models could generally reproduce the variability and trends of East Asian temperatures observed in seasonal temperature reconstructions, but might largely underestimate the seasonal differences of temperature than those seen in the reconstructed data.
Based on the new findings, the authors inferred a further weakening of seasonal temperature difference in the future as a result of ongoing anthropogenic warming. If it is true, this will have important social and ecological implications, e.g., plant phenology and the transmission of seasonal diseases.
See the article:
Wang J, Yang B, Wang Z, Luterbacher J, Ljungqvist F C. 2023. Recent weakening of seasonal temperature difference in East Asia beyond the historical range of variability since the 14th century. Science China Earth Sciences, 66(5): 1133–1146, https://doi.org/10.1007/s11430-022-1066-5
JOURNAL
Science China Earth Sciences
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