The calcium carbonate (CaCO3) profile of a recent sediment core, drilled in the Ionian Sea in 1979, is studied. The CaCO3 content of the sediment has been measured at regularly spaced intervals of Δd=0.25 cm corresponding to Δt=3.87 yr from AD 170 to the present. The CaCO3 profile of the core closely resembles the radiocarbon time series as deduced from tree ring data. The two records have a correlation coefficient of about 0.8 and show strikingly similar long-term variations. This result presumably follows from the fact that both systems take part in the carbon cycle. The spectral analysis of the CaCO3 time series reveals the presence of the well known periodicity with period ca: 200 years, characteristic of the Δ14C record. Since the CaCO3 content of sea sediments is governed by biological, physical and chemical processes in surface sea waters, which in turn are strongly influenced by climatic conditions, and since the ≈200 yr Δ14C wave is known to be governed by solar modulation of galactic cosmic rays, the tuning of these two records on the same frequencies suggests a strong Sun-climate relationship. ¿ American Geophysical Union 1990