Radiocarbon Data from the Late 18th Century as a Reflection of Solar Activity Variation, Natural Climate Change, and Anthropogenic Activity

The data on the content of the C-14 cosmogenic isotope in the natural archives make it possible to study the solar activity (SA) in the past centuries and millennia. However, the C-14 content in the natural archives is influenced not only by the intensity of incoming galactic cosmic rays (GCRs), which are modulated by the interplanetary magnetic field and vary according to SA variations; changes in the geomagnetic field and in the Earth's climate also affect radiocarbon data. In particular, climate variation leads to the redistribution of radiocarbon between natural reservoirs. In the 19th century, increased anthropogenic activity was also reflected in radiocarbon data. This article presents the results of the reconstruction of the rate of C-14 production under the influence of GCRs with allowance for the above factors. It is shown that the rate of radiocarbon release from the deep ocean into the surface layer and the atmosphere has increased since the second quarter of the 19th century. Apparently, this process is natural.