What was done
In the words of the authors, "high-resolution records of ð¹³C and ð¹⁸O in stalagmite SF-1 from Buddha Cave [33°40'N, 109°05'E] are used to infer changes in climate in central China for the last 1270 years in terms of warmer, colder, wetter and drier conditions."

What was learned
Among the climatic episodes evident in the authors' data were "those corresponding to the Medieval Warm Period, Little Ice Age and 20th-century warming, lending support to the global extent of these events."  Specifically, their record begins in the depths of the Dark Ages Cold Period, which ends about AD 965 with the commencement of the Medieval Warm Period, which continues to approximately AD 1475, whereupon the Little Ice Age sets in and holds sway until about AD 1825, after which the warming responsible for the Modern Warm Period begins.

With respect to hydrologic balance, the last part of the Dark Ages Cold Period was characterized as wet, followed by a dry, a wet, and another dry interval in the Medieval Warm Period, which was followed by a wet and a dry interval in the Little Ice Age, and finally a mostly wet but highly moisture-variable Modern Warm Period.  Some of this latter enhanced variability is undoubtedly due to the much finer 1-year time resolution of the last 150 years of the record as compared to the 3-4-year resolution of the prior 1120 years.  This most recent improved resolution thus led to the major droughts centered on AD 1835, 1878 and 1955 being very well delineated.

The authors' data also revealed a number of other cycles superimposed on the major millennial-scale cycle of temperature and the centennial-scale cycle of moisture.  They attributed most of these higher-frequency cycles to cyclical solar and lunar phenomena, concluding that the summer monsoon over eastern China, which brings the region much of its precipitation, may thus "be related to solar irradiance."

What it means
Earth's climate is determined by a conglomerate of cycles within cycles within cycles within ? cycles, nearly all of them totally independent of the air's CO2 concentration.  Hence, to do as climate alarmists do, and call the warming of the 20th century outside the bounds of natural variability (and thus due to the concurrent rise in the air's CO2 content) is just not valid.  There is nothing unusual about the Modern Warm Period, it being no more nor less than simply the most recent warm node of the millennial-scale climatic oscillation that has been operating for as long as we can determine.