Yancheva et al. reply

Replying to: De’er Zhang & Longhua Lu Nature 450, doi:10.1038/nature06338 (2007) Zhang and Lu1 argue that Chinese historical climate records contradict certain of our interpretations2 based on Lake Huguang Maar sediment records. Interpreting these records as an indicator for winter monsoon winds and Chinese cave records as an indicator for summer monsoon rainfall3, we observed2 an inverse relationship between winter and summer monsoons on a millennial timescale over the past 16,000 yr. In sediments deposited during the period of Classical Chinese dynastic history, we found evidence for a temporal coincidence between winter monsoon strengthening and the terminations of important dynasties2. Extrapolating the inverse monsoon relationship to these multidecadal timescales, we suggested that reduced summer rainfall contributed to dynastic terminations, including that of the Tang (ad 618–907). Zhang and Lu1 challenge the validity of the summer/winter monsoon relationship on the grounds that historical records indicate that relatively cold winters tended to be associated with relatively wet summers over the period they considered. They argue that the Tang dynasty decline was associated with cold winters, in agreement with our findings2, but they find no evidence for rainfall changes having contributed to the decline of the Tang.