This paper by Minze Stuiver and Thomas F. Brazunas discusses the complexities of calibrating 14C ages of marine samples, which differ from those of atmospheric samples due to the presence of reservoirs like lakes and oceans. The authors introduce a correction method that accounts for the offset between reservoir and atmospheric 14C activity, represented by a reservoir age (R(t)). They use a global carbon model to simulate 14C variations in the world oceans, considering both secular changes and regional offsets (ΔR). The model is calibrated using tree-ring and coral 14C data, and it is shown that the long-term trend of 14C age vs. calibrated age in the oceans parallels that of the atmosphere, but short-term variations are smoothed in the oceans. The authors also discuss the impact of regional variations in atmospheric 14C activity and the influence of climate-induced changes in global carbon reservoirs. They present a detailed calibration curve for marine samples and demonstrate the validity of their approach through comparisons with foraminifera data. The paper highlights the importance of accounting for regional reservoir ages and the limitations of assuming a constant reservoir age.This paper by Minze Stuiver and Thomas F. Brazunas discusses the complexities of calibrating 14C ages of marine samples, which differ from those of atmospheric samples due to the presence of reservoirs like lakes and oceans. The authors introduce a correction method that accounts for the offset between reservoir and atmospheric 14C activity, represented by a reservoir age (R(t)). They use a global carbon model to simulate 14C variations in the world oceans, considering both secular changes and regional offsets (ΔR). The model is calibrated using tree-ring and coral 14C data, and it is shown that the long-term trend of 14C age vs. calibrated age in the oceans parallels that of the atmosphere, but short-term variations are smoothed in the oceans. The authors also discuss the impact of regional variations in atmospheric 14C activity and the influence of climate-induced changes in global carbon reservoirs. They present a detailed calibration curve for marine samples and demonstrate the validity of their approach through comparisons with foraminifera data. The paper highlights the importance of accounting for regional reservoir ages and the limitations of assuming a constant reservoir age.