气候变化领域集成服务门户

Since the late 1990s, the global warming has ground to a halt, which has sparked a rising interest among the climate scientists. The hiatus is not only observed in the globally averaged surface air temperature (SAT), but also in the China winter temperature trend, which turns from warming during 1979-1997 to cooling during 1998-2013. However, the reasons and the relevant mechanisms of the warming hiatus are far from being understood. Arctic sea ice (ASI), one of the tipping points of the Earth system change, has contributed to the dramatic climate change. It is found that the ASI over the Barents-Kara Seas in the warming hiatus period (1998-2013) has declined about three times faster than that in the previous continuing warming period (1979-1997). The observational analysis and the wave ray trajectories suggest that, for the hiatus period, the ASI over the Barents-Kara Seas explains 61.4% of the decreasing SAT trend and 14.4% of the interannual SAT variation in China. The possible dynamical process is as follows: the anomalous ASI loss associated with the significant warming in Barents-Kara Seas can excite a downstream teleconnection wave train pattern over the Eurasia continent. The significant easterly winds in the subpolar region slacken the polar-front jet, while the anomalous westerly winds over the Tibetan Plateau reinforce the East Asian subtropical jet. As a result, the concurrent out-of-phase variations in the intensity of the jets lead to the cold flow moving southward from the Arctic and converging in China. The northwest-southeast tilted dipole pattern of the height centers over Eurasia, accompanied with the weakened polar-front jet, usually favors the persistence of Ural blocking (UB). Furthermore, in the lower level, the anomalous high pressure belt over the northern Eurasian continent can help cold northeasterly winds blow from the Russian Far East to China and bring about the cold winters. Thus, the accelerated melting of ASI can exert a profound influence on China warming hiatus in recent two decades.