Significant greening in the western Tibetan Plateau and surroundings occurred after the 1970s

Vegetation greening on the Tibetan Plateau (TP) has profoundly changed the connection between terrestrial ecosystems and regional carbon, water, and energy cycling, but existing research on vegetation greenness can only be traced back to the 1980s, because of the scarcity of long-term remote sensing data. Here we present an ice-core record of pollen accumulation rates with a 3-year resolution during 1935-2012 AD for the western TP. Based on backward trajectory and wind data, we identified the pollen source region and transport mechanisms. We found that the 3-year total pollen accumulation rate (TPAR3a) is a good indicator of vegetation coverage of the source region, and our data showed that the greening of the western TP and surroundings began as early as 1935 AD, mostly due to regional warming and moistening. The greening trend became more significant after the 1970s, which is mostly related to the significant increase in temperature.