As the “third pole” of the planet, Tibetan plateau has been warming at a faster pace than the global average. But how the ecosystem responded to the warming has been under intensive debate. Phenology is a sensitive and critical feature of vegetation, and it could reflect the effects of climate variability and change on vegetation growth. Thus, monitoring the vegetation phenology changes at regional and global scales could help quantify the effects of climate change on terrestrial ecosystems.

Dr. ZHANG Yangjian and Dr. XIAO Xiangming’s team found that vegetation ecosystem on Tibetan plateau has been responding to global warming in a highly sensitive manner. Through integrating multiple remote sensing data sources and in combination with field validation, Zhang et al., found that the green up data of Tibetan vegetation ecosystem has been advancing mostly.

The significant advancing of the start of growing season on the Tibetan Plateau during the past 30 y may have significant implications for land–atmosphere dynamics and interactions. On the other hand, the prolonged growing season can potentially enhance the carbon sink capacity of terrestrial ecosystems, which has been shown in terrestrial ecosystems in the northern mid and higher latitudes during 1980–2002.

An earlier start of the growing season will change forage production for livestock (e.g.,yak), which could affect the local economy significantly. Finally the study emphasizes that the quality of remote sensing data needs to be carefully evaluated when they are used to retrieve vegetation phenology information and vegetation greenness at a large scale, and the integration of multiple sources of datasets, especially relying more on field records, would better address issues of uncertainty related to remote sensing applications in vegetation phenology studies.

The results have been published in PNAS(Geli Zhang, Yangjian Zhanga, Jinwei Dong, and Xiangming Xiao，2013 Green-up dates in the Tibetan Plateau have continuously advanced from 1982 to 2011. Proceedings of the National Academy of Sciences. 110(11): 4309-4314).