What was done
Tree-ring chronologies from northeastern Mongolia were used to reconstruct annual precipitation and streamflow histories for the period 1651-1995.

What was learned
 Analyses of both standard deviations and 5-year intervals of  extreme wet and dry periods revealed that "variations over the  recent period of instrumental data are not unusual relative to the  prior record."  The authors do state, however, that the  reconstructions "appear to show more frequent extended wet  periods in more recent decades," but they note that this observation "does not demonstrate unequivocal evidence of an increase in precipitation as suggested by some climate models."  Spectral analysis of the data also revealed significant periodicities around 12 and 20-24 years, suggesting "possible evidence for solar influences in these reconstructions for northeastern Mongolia."

What it means
Climate model predictions of increased hydrometeorological extreme events, a corollary of the CO2-induced global warming hypothesis, do not jibe with real-world data from northeastern Mongolia.  Could it be that the model predictions are wrong?  Sure could!