NOAA/WDS Paleoclimatology - Yang - Delingha - JUPR - ITRDB CHIN067

An annually resolved and absolutely dated ring-width chronology spanning 4,500 y has been constructed using subfossil, archaeological, and living-tree juniper samples from the northeastern Tibetan Plateau. The chronology represents changing mean annual precipitation and is most reliable after 1500 B.C. Reconstructed precipitation for this period displays a trend toward more moist conditions: the last 10-, 25-, and 50-y periods all appear to be the wettest in at least three and a half millennia. Notable historical dry periods occurred in the 4th century BCE and in the second half of the 15th century CE. The driest individual year reconstructed (since 1500 B.C.) is 1048 B.C., whereas the wettest is 2010. Precipitation variability in this region appears not to be associated with inferred changes in Asian monsoon intensity during recent millennia. The chronology displays a statistical association with the multidecadal and longer-term variability of reconstructed mean Northern Hemisphere temperatures over the last two millennia. This suggests that any further large-scale warming might be associated with even greater moisture supply in this region.

本研究利用青藏高原东北部的亚化石、考古遗存及活树圆柏样本，构建了一条跨度达4500年、具备年分辨率与绝对定年特征的树轮宽度年表（ring-width chronology）。该年表反映了年均降水量的变化趋势，且在公元前1500年之后的时段可靠性最高。该时段的重建降水序列呈现向更湿润环境演化的趋势：过去10年、25年及50年的时段，均为至少3500年以来最湿润的时期。显著的历史干旱时段分别出现在公元前4世纪与公元15世纪后半叶。在公元前1500年以来的重建序列中，最干旱的单个年份为公元前1048年，而最湿润的年份则为2010年。该区域的降水变率似乎与近数千年来推断的亚洲季风强度变化不存在显著关联。该树轮宽度年表与过去两千年间重建的北半球平均温度的年代际及更长时间尺度的变率存在统计学关联。这表明，未来任何大规模的进一步增温，都可能与该区域更充沛的水汽供给相关联。