Science. 1988 Jun 10;240(4858):1517-9. doi: 10.1126/science.240.4858.1517.
Millennium-old bald cypres trees (Taxodium distichum [(L.) Rich.] have ben used to develop a 1614-year reconstruction of the June Palmer drought severity index for North Carolina. This proxy paleoclimatic record indicates that the growing season climate of North Carolina has undergone many changes between significantly different regimes of drought and wetness that persist for approximately 30 years. Alternating wet and dry regimes were particularly well developed during the Medieval Warm Epoch (A.D. 1000 to 1300). The record June droughts in 1985 and 1986 and the preceding three decades of much wetter than average conditions both appear to have been rare climatic events, equaled only five times each since A.D. 372.
千年古柏（Taxodium distichum [(L.) Rich.]）被用于建立北卡罗来纳州的 1614 年 6 月 Palmer 干旱严重指数重建。这个代理古气候记录表明，北卡罗来纳州的生长季节气候在持续约 30 年的干旱和湿润显著不同的状态之间经历了许多变化。干湿交替的状态在中世纪暖期（公元 1000 年至 1300 年）尤为发达。1985 年和 1986 年的记录性干旱，以及之前 30 年的比平均水平湿润得多的情况，这两者似乎都是罕见的气候事件，自公元 372 年以来，每一次都只出现过 5 次。
