Review of climate and cryospheric change in the Tibetan Plateau

Abstract

The Tibetan Plateau (TP), with an average elevation of over 4000 m asl and an area of approximately2.5 × 106 km2, is the highest and most extensive highland in the world and has been called the ‘ThirdPole’. The TP exerts a huge influence on regional and global climate through thermal andmechanical forcing mechanisms. Because the TP has the largest cryospheric extent outsidethe polar region and is the source region of all the large rivers in Asia, it is widelyrecognized to be the driving force for both regional environmental change and amplificationof environmental changes on a global scale. Within China it is recognized as the‘Asian water tower’. In this letter, we summarize the recent changes observedin climate elements and cryospheric indicators on the plateau before discussingcurrent unresolved issues concerning climate change in the TP, including thetemporal and spatial components of this change, and the consistency of changeas represented by different data sources. Based on meteorological station data,reanalyses and remote sensing, the TP has shown significant warming duringthe last decades and will continue to warm in the future. While the warming ispredominantly caused by increased greenhouse gas emissions, changes in cloud amount,snow-albedo feedback, the Asian brown clouds and land use changes also partlycontribute. The cryosphere in the TP is undergoing rapid change, including glacierretreat, inconsistent snow cover change, increasing permafrost temperatures anddegradation, and thickening of the active layer. Hydrological processes impacted byglacial retreat have received much attention in recent years. Future attentionshould be paid to additional perspectives on climate change in the TP, such as thevariations of climate extremes, the reliability of reanalyses and more detailedcomparisons of reanalyses with surface observations. Spatial issues include theidentification of whether an elevational dependency and weekend effect exist, and theidentification of spatial contrasts in temperature change, along with their causes.These issues are uncertain because of a lack of reliable data above 5000 m asl.