Caspar Amman Uncertainty of Causes and Climate Variability during Past Centuries – Regional and Climate Mode Response

Fingerprinting of external forcing Clear separation of anthropogenic from naturally forced climate changes is a fundamental prerequisite for any successful impact assessment of potential future climate change. The available instrumental record is both too short and contaminated through competing natural and anthropogenic forcings. An expansion of the records over many centuries provides a more appropriate framework for establishing an understanding of the magnitude and spatiotemporal characteristics of natural forcings. But searching for the impact of past external forcing is also an outstanding uncertainty showcase: On one hand the forcings are known only through proxies, not absolute measures, while at the same time the climate records that contain the climatic response signals are often restricted to individual proxy records from point sources. Two tracks for approaching this problem are under active investigation.