Zonal plant communities are the best climatic indicators because they thrive under specific climatic conditions. However, palaeoclimatic estimates based on mere comparisons of local fossil plant assemblages, even if assessed by multivariate methods, may be misleading, if the taphonomical bias is neglected. The fossil record expresses only limited parts of the vegetation of a given period. The example of the Lower Miocene section at Bílina, North Bohemian Basin, shows how quickly the composition of the plant megafossil record changes as a result of different environmental factors and sedimentary settings. These changes can imitate climatic oscillation because swamp, fluvial and upland facies represented within this site have different vegetation–palaeoclimatic aspects. On the other hand, if one compares two assemblages originating from the same sedimentary and environmental setting (preferably mesophytic conditions), the resulting palaeoclimatic changes can be estimated more safely. Two local assemblages from the Oligocene volcanic area of the České středohoří Mts in North Bohemia are of mesophytic character. Both are embedded in diatomites deposited in crater–maar lakes. The assemblage of Suletice (20–29 Ma), with prevailing thermophilous elements, indicates more warm-temperate conditions, whereas the assemblage of Bechlejovice (27 Ma), composed mostly of deciduous broadleaved trees and shrubs, corresponds to a temperate climate. Thus, together, these two floral assemblages suggest that a climatic oscillation occurred within Late Oligocene time in Central Europe.
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Climates: Past and Present
The climate of the early Earth was probably very warm and has, in general, reduced since the Archean. However, it now seems that the world is about 0.6°C warmer than it was 100 years ago and estimates of the rate of global warming over the next century range from 0.16°C to 0.35°C per decade. Concurrently, global sea-level is predicted to rise from 2.4 to 10 cm per decade. These rates of change are much faster than those normally associated with the geological record, causing geologists and palaeontologists to reassess their data and their forecasts on rates of future change.
With the current interest in global climatic change and, more specifically, with global warming, it is clear that palaeontologists have valuable information to provide on the impacts of past climatic change. This volume contains papers from an international array of such geologists and palaeontologists, showing how studies of micro- and macrofossils, plant and vertebrate fossils from a range of geological ages have contributed to our understanding of how climate affects both local and more widespread areas. The contributions are arranged in geological order, ranging from the Permo-Carboniferous to the post-glacial recovery of the last 18,000 years, with an emphasis on climate change during the last two million years, particularly in NW Europe.
Climates: Past and Present will be of interest to palaeontologists, geologists and palaeoclimatologists who specialize in climatic reconstructions and any professionals enagaged in research into the geological aspects of climate change.