How much do humans contribute to today's climate change? This is one of research's central questions. To give a proper answer, we have to know the parameters of natural variability, e.g. the temperatures in oceans, above the continents and in polar regions. We are able to reconstruct past climate changes from historical data collections or by evaluating documented observations.
However, existing data collections which allow the quantification of climate change on global level are to short and already underlie the strong influence of humans on the natural conditions. Therefore, to understand the climate system prior to the anthropogenic influence, we have to follow another path. Proxies (representative data) help us to understand climate and environmental conditions of the past. In combination with complex numerical models of the climate system, climate archives provide us with an excellent test bed for a better understanding of the past climate variability
The following time scales are of special interest for the study of climate variability and climate change:
Holocene and Present | Quaternary | Pre-Quaternary