Observed changes of cryosphere in China over the second half of the 20th century: an overview

During approximately the past five decades, changes in snow cover, mountain glaciers, frozen ground (including permafrost), sea ice and river ice have been observed in China. However, most data were published in Chinese and thus unknown to the international communities. Here we review these published results to show an overview of cryospheric changes in China for the last ~50 years. Long-term variability of snow cover over the Qinghai–Xizang (Tibetan) Plateau (QXP) is characterized by large interannual variability superimposed on a continuously increasing trend. Glacier changes in western China vary remarkably in different regions. Although in most mountains the glaciers display a retreating trend (~80%) or have even vanished, some glaciers (~20%) are still advancing. Frozen ground (including permafrost) has experienced a rapid decay since the 1980s, and these changes are occurring both in the QXP and in the cold regions of north China. Sea-ice areas in the Bohai and north Yellow Seas have been shrinking since the 1970s. Interannual variations possibly relate to the solar cyles, and sea-ice extent extremes relate to El Niño–Southern Oscillation (ENSO) events. The freeze-up and break-up dates of river ice in north China in the 1990s are, on average, 1–6 days later and 1–3 days earlier, respectively, than the 1950s–1990 mean. Frozen duration and the maximum thickness of river ice are, respectively, 4–10 days shorter and 0.06–0.21cm thinner in the 1990s than the average.