Time series of d13C and its MEM Spectrum. The top plot shows the observed data 
(not available) organized as average values in 100-yr bins (1-100yr; 101-200yr;
..., available at NOAA Paleo. The events at 4.2 Ka and at 8.2 Ka are clearly visible.
I note that the average d13C values grow from ~9 Ka to ~3.2 Ka and , after
that date, they became stable up to now (i.e. 2013 CE), within some ~500 yrs
wide oscillations.