Yet, it is clear that to understand the present warming, and the importance of the antropogenic share, having a better understanding of the past is useful. I'm currently reading a book with an interesting round up on the changes in the holocene temperature.
The summary reads :
Wilst there is now overwhelming evidence that greenhouse-gas pollution is becoming the dominant process responsible for global warming, it is also clear that the climate system varies quite naturally on different time-scales.
Predicting the course of future climate change consequently requires an understanding of the natural variability of the climate system as well as the effects of human-induced change.
This book is concerned with our current understanding of natural climate change, its variability on decadal to centennial time-scales, the extent to which climate models of different kinds simulate past variability, and the role of past climate variability in explaining changes to natural ecosystems and to human society over the later part of the Holocene.
The book highlights the need to improve not only our understanding of the physicalsystem through time but also to improve our knowledge of how people may have influenced the climate system in the past and have been influenced by it, both directly and indirectly. This ground-breaking text addresses predictable modification in the climate system in the context of global warming.
Ideal for researchers and advanced students, it explores current thinking on natural climate change. It addresses the natural variability of the climate system in the context of global warming. It contributes substantially to the ongoing discussion on global warming. It integrates state-of-the-art research and brings together modeling and data communities in a balanced way. It considers questions of climate change on different time-scales.
The book starts with some history and I'm sure many people will be surprised that p.ex. the Holocene Climate Optimum was something known to Scandinavian scientists in the 1820's already... And i'm equally sure that many people will be more surprised how much science actually has discoverd since that time. Well worth reading !