Biological evidence of past environments and climatic changes

This paper will examine some of the types of biological evidence that allow us an insight into past environments and will consider some of the concepts that affect and limit our interpretations of past environments, and through them climatic changes.Scandinavia was the birthplace of palaeoenvironmental studies; basic to these being the concepts of speciation formulated in Uppsala by Linnaeus nearly 250 years ago. Sernander proposed his bog regeneration theories in 1910 and von Post gave his first two lectures on pollen analysis in 1916. Iversen demonstrated how the impact of human activities could be disentangled from climate change and later discussed the effects of lags in the vegetation at the start of the post glacial. These laid the framework for much that I will describe.At the turn of the century the two botanists Blytt and Sernander proposed a sub-division of the recent past (the post glacial period or Holocene as we now call it) on the basis of biological evidence preserved in bogs. They described wood layers in peat bogs and introduced the terms Boreal and Sub-Boreal for the time spanned by the wood layers, and the Atlantic and Sub-Atlantic for what they interpreted as the intervening wetter periods. These wood layers are as obvious now as they were in 1900 and the terms Boreal and Atlantic have gone in and out of fashion over the intervening years.