The 13 C/ 12 C ratio of C 3 plant matter is thought to be controlled by the isotopic composition of atmospheric CO 2 and stomatal response to environmental conditions, particularly mean annual precipitation (MAP). The effect of CO 2 concentration on 13 C/ 12 C ratios is currently debated, yet crucial to reconstructing ancient environments and quantifying the carbon cycle. Here we compare high-resolution ice core measurements of atmospheric CO 2 with fossil plant and faunal isotope records. We show the effect of pCO 2 during the last deglaciation is stronger for gymnosperms (−1.4 ± 1.2‰) than angiosperms/fauna (−0.5 ± 1.5‰), while the contributions from changing MAP are −0.3 ± 0.6‰ and −0.4 ± 0.4‰, respectively. Previous studies have assumed that plant 13 C/ 12 C ratios are mostly determined by MAP, an assumption which is sometimes incorrect in geological time. Atmospheric effects must be taken into account when interpreting terrestrial stable carbon isotopes, with important implications for past environments and climates, and understanding plant responses to climate change.

The paucity of Southern Hemisphere archeomagnetic data limits the resolution of paleosecular variation models. At the same time, important changes in the modern and historical field, including the recent dipole decay, appear to originate in this region. Here a new directional record from southern Africa is presented from analysis of Iron Age (ca. 425–1550 CE) archeological materials, which extends the regional secular variation curve back to the first millennium. Previous studies have identified a period of rapid directional change between 1225 and ∼1550 CE. The new data allow us to identify an earlier period of relatively rapid change between the sixth and seventh centuries CE. Implications for models of recurrent flux expulsion at the core‐mantle boundary are discussed. In addition, we identify a possible relationship of changes recorded in these African data with archeomagnetic jerks.

Chronology assumes a central role in the process of historical and archaeological reconstruction by allowing us to time the change and development of human societies. Dating provides a framework for linking individual events together. It is the backbone for historical narratives, and connections between environmental and archaeological records on a global scale. However, until today, establishing a reliable chronology for ancient human societies and civilizations using pottery has remained one of the most contested topics of scientific discourse. Although the field of chronology has been revolutionized by modern historical and archaeological critical methods, through assessing historical sources and material