ABSTRACT
The ice ages put a certain pressure on human evolution, because of the cold climate background state affecting the food supply, especially in the mid-latitudes. Changes in obliquity represent the most important astronomical forcing for the climate of the past 2,000 years, because the increase in the angle leads, for instance, to a decline in the June–August insolation and an increase in the spring insolation over the Northern Hemisphere. A very important pacemaker on those timescales of multi-year to decadal climate variability relates to changes in volcanic activity. The concept of internal climate variability attracted an increased consideration as an integral part of the climate system and its potential implications for future climate change. A pre-requisite for producing spatially and temporal highly resolved climate reconstructions relates to the availability of high-quality proxy data and/or historical documents and observations. A complementary approach, reconstructing climate of the Common Era is to use climate models.
