China’s Recent Progresses in Polar Climate Change and Its Interactions with the Global Climate System

During the recent four decades since 1980,a series of modern climate satellites were launched,allowing for the measurement and record-keeping of multiple climate parameters,especially over the polar regions where traditional observations are difficult to obtain.China has been actively engaging in polar expeditions.Many observations were conducted during this period,accompanied by improved Earth climate models,leading to a series of insightful understandings concerning Arctic and Antarctic climate changes.Here,we review the recent progress China has made concerning Arctic and Antarctic climate change research over the past decade.The Arctic temperature increase is much higher than the global-mean warming rate,associated with a rapid decline in sea ice,a phenomenon called the Arctic Amplification.The Antarctic climate changes showed a zonally asymmetric pattern over the past four decades,with most of the fastest changes occurring over West Antarctica and the Antarctic Peninsula.The Arctic and Antarctic climate changes were driven by anthropogenic greenhouse gas emissions and ozone loss,while tropical-polar teleconnections play important roles in driving the regional climate changes and extreme events over the polar regions.Polar climate changes may also feedback to the entire Earth climate system.The adjustment of the circulation in both the troposphere and the stratosphere contributed to the interactions between the polar climate changes and lower latitudes.Climate change has also driven rapid Arctic and Southern ocean acidification.Chinese researchers have made a series of advances in understanding these processes,as reviewed in this paper.

The Southern Hemisphere sudden stratospheric warming of September 2019

Sudden stratospheric warmings(SSWs)are extreme cases of stratospheric polar vortex weakening[1].They are termed minor when a reversal of the stratospheric meridional temperature gradient in the subpolar region at 10 hPa and poleward of 60occurs,or major when this is accompanied by a complete reversal of the stratospheric circumpolar westerly jet[2].Although SSWs occur in both hemispheres,major SSWs are usually observed in the Northern Hemisphere,with a frequency of approximately six per decade.In contrast,only one major SSW has been recorded in the Southern Hemisphere,which occurred in 2002[3].