Fennoscandian AND Yamalian tree-ring anatomy shows a warmer modern than medieval climate

Earth system models and various climate proxy sources indicate that global warming is unprecedented during at least the Common Era. However, tree-ring proxies often estimate temperatures during the Medieval Climate Anomaly (950–1250 CE) to be similar, or exceed, those recorded for the past century. This is in contrast to simulation experiments at regional scales. This not only calls into question the reliability of models as well as proxies, but also contributes to uncertainty in future climate projections. Here we show that the current climate of Fennoscandia is substantially warmer than during the medieval period. This indicates a dominant role of anthropogenic forcing in climate warming even at the regional scale, thereby reconciling differences between reconstructions and model simulations. These results were obtained using an annually resolved 1,170-year-long tree-ring record that relies exclusively on tracheid anatomical measurements from Pinus sylvestris trees. Now we can confirm these results using new tree-ring anatomy data developed from Larix Sibirica tree-ring samples from the Yamal Peninsula in North-western Siberia over the past millennia. Both these datasets provide exceptional high-fidelity measurements of instrumental temperature variability during the warm season. We call for the construction of more such millennia-long records to continue to improve our understanding and reduce uncertainties around historical and future climate change at increasingly larger scales.