• Asian summer monsoon;
  • δ18O;
  • tree rings;
  • Juniperus tibetica;
  • Southern Tibet;
  • precipitation reconstruction

[1] Recent warming in High Asia might have a strong impact on Asian summer monsoon variability with consequences for the hydrological cycle. Based on correlations between climate data, the tree-ring δ18O of high-elevation junipers is an indicator of August precipitation. Thus, our 800-year long annually resolved oxygen isotope series reflects long-term variations in summer monsoon activity on the southern Tibetan plateau. Summer precipitation was reduced during 13th–15th centuries and since the 19th century, whereas the Little Ice Age period (15th–19th century) was rather moist. The late 20th century was among the driest periods during the past 800 years, showing a tendency to slightly wetter conditions after AD 1990.