On September 25 at 23:00 Beijing time, Professor Xu Guobao from the School of Urban and Environmental Sciences at Northwest University made a significant contribution by publishing a comprehensive article titled "Jet stream controls on European climate and agriculture since 1300 CE" as the lead author in the prestigious international journal, Nature.

The research conducted by Professor Xu Guobao and his co-author, Professor Valerie Trouet, alongside experts in tree rings, climatology, biology, and history from 24 research units across 12 countries, delved into the impact of shifting atmospheric jet streams on European forest ecosystems, society, and economy. Their study unveiled the diverse climate conditions that have influenced agriculture, economy, and society in northwest and southeast Europe.

Jet streams, rapid high-altitude wind currents encircling the Earth in both hemispheres, play a pivotal role in shaping weather patterns. The position of these jet streams is dynamic, influenced by high and low-pressure systems, and can lead to significant changes in climate conditions, including extreme events such as  heatwaves, floods, and droughts, ultimately impacting agricultural productivity and global food security.

Despite the critical role of jet streams in climate dynamics, historical understanding of their variability remains limited, making it challenging to grasp how modern climate change influences these phenomena and associated extreme events.

To analyze the historical changes in European jet streams, the research team reconstructed jet stream variations over the past 700 years using temperature-sensitive tree ring samples from various regions in Europe.

Professor Xu Guobao and his collaborators discovered that the jet stream climate patterns in northwest and southeast Europe have persisted for centuries, with the most pronounced effects observed when the Arctic jet stream deviates abnormally northward or southward.

Their research, drawing on climate reconstruction data and extensive historical literature on extreme weather events, harvests, famines, and more, highlighted the link between jet stream latitude shifts and impacts on biological phenology, agricultural economy, and human populations.

Xu Guobao (left) uses growth cones to obtain cypress tree cores in the Chaidamu Basin.

The findings not only deepen our understanding of natural climate variability pre-industrialization but also provide crucial data for enhancing climate models used to predict future climate trends. This research sheds light on how natural climate variability influences human societies.

Xu Guobao: Ph.D., Professor and Doctoral Supervisor at the School of Urban and Environmental Sciences, Northwest University. His main research focus is on tree rings and global change.

Professor Xu Guobao, a Ph.D. holder, Professor, and Doctoral Supervisor at Northwest University, specializes in tree rings and global change. The article, with Professor Xu Guobao as the lead author, features the Tree Ring Laboratory at the University of Arizona as the corresponding unit, with Professor Valerie Trouet as the corresponding author. The collaborative effort involved 23 units, including prestigious institutions such as the Northwest Institute of Ecological Environment and Resources of the Chinese Academy of Sciences, University of Arizona, University of Cambridge, University of Mainz, University of Gothenburg, and University of Stockholm.