Time series of d13C and its LOMB spectrum. Numerical values are the
digitalization of Kluge et al., 2020, figure 5, upper panel (say fig.5a).
The series shows an abrupt change in Carbon at 1 Ka (~ 1000 CE) while the
slope from 4.6 Ka through 1 Ka grows very slowly (in practice it is
constant). If d13C can be considered a proxy for a wetter climate, the
series shows a sudden increase (of rain, I suppose) at about the beginning of 
the LIA, in Greece.