The effects of climate change in China
A study published by Advances in Atmospheric Sciences in February explains why some Northern Hemisphere countries are increasingly affected by extremely-cold weather events against a global warming background. The case study chosen is the severe Chinese winter of 2020-21.
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In the first half of winter 2020/21, China experienced an extremely cold period in both northern and southern regions, recording record low temperatures at many stations across the country.
The co-author of the study, Prof. Zheng Fei of the International Center for Climate and Environment Science (ICCES), the Institute of Atmospheric Physics (IAP) of the Chinese Academy of Sciences (CAS), reported that two events are responsible: warming of the Arctic, and cooling of the tropical Pacific.
Arctic warming causes ice to melt, disrupting surface and ocean temperatures. La Niña, the cold phase of extreme climate cycles in the tropical Pacific, drops ocean temperatures by up to -5 degrees Celsius by affecting atmospheric and global wind circulation.
La Niña is a periodic climatic phenomenon. During these periods, sea surface temperatures in the eastern equatorial part of the central Pacific Ocean drop 3-5 degrees Celsius.
The combined effects of Arctic warming, mainly induced by global warming, and tropical Pacific cooling, caused by La Niña, intensified cold air intrusions from polar regions to mid-to-high-latitudes, which further influenced cold conditions in China during the first half of winter 2020-21. This synergistic effect can be regarded as a necessary background for triggering the cold surges invading most countries in East Asia and North America.”
To predict the evolution of La Niña in particular, the researchers used the ensemble prediction system developed at the Institute of Atmospheric Physics and the Chinese Academy of Sciences. The system evaluates the last 20 years of a selected climate event and offers up to a one-year prediction of how this event might evolve.
The synergistic effect of extreme weather events will continue to be researched through observation, climate simulation, and data assimilation. The goal is to be able to offer a more reliable tool to improve seasonal forecasts for countries in the Northern Hemisphere.
Topics: Climate change in China, why winters are getting colder and colder
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