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Keywords:

  • Tibetan Plateau;
  • surface pressure;
  • surface warming

Abstract

The Tibetan Plateau (TP) is the world's highest and largest plateau. By acting as an elevated thermal source as well as a topographic barrier, the TP has a profound impact on both local weather and global climate. The TP has recently been warming at a faster rate than the entire Northern Hemisphere. However, the lack of instrumental records prior to the 1950s limits our ability to place this recent warming in a longer-term context. Here we show that over the plateau, because of its high elevation, the surface pressure is a proxy for surface air temperature and that since the 1870s there has been a statistically significant increase in surface pressure over the TP, that has undergone an acceleration since the 1980s. There is also a compensatory decrease in surface pressure in the surrounding lower elevation region. Furthermore, we show that since the 1870s the surface pressure over the plateau is correlated with the Northern Hemisphere temperature record at a statistical significance that exceeds the 99 percentile. Finally, the trend in surface pressure over the plateau is consistent with an increase in annual mean surface air temperature of ∼0.4°C since the 1870s and an increase of ∼1°C since the 1980s. The long-term warming over the TP derived from the surface pressure trend is of the same order as the long-term hemispheric warming. This suggests that the increased rate of warming recently observed over the plateau is not a long-term phenomenon. Copyright © 2012 Royal Meteorological Society