Here we show how the frequency scaling of a climate reconstruction from sediment proxy records is affected by various sources of uncertainty. Specifically, analytic expressions are derived and illustrated for the power spectral density of a climate reconstruction, based on a simple model that takes into account: the spectral structure of the true climate, uneven recording throughout the year, precession-like orbital modulations of the seasonal cycle, bioturbation, sampling of a finite number of signal carriers from discontinuous slices of sediment material, uncorrelated measurement noise; and that includes the effects of spectral aliasing and leakage. The basic behaviour and the properties of the model are demonstrated, and the implications for the interpretation of climate reconstructions are discussed.