Plant macrofossils and palaeoclimates

Jack Wilkin (UK) Palaeoclimatology is the study of past climates and environments using climate proxies, that is, the preserved physical characteristics of past, rather than using direct measurements of variables, such as temperature, levels of CO2 and so on. Many different types of proxies are used including, but not limited to, ice cores (Petit et al., 1999), lake and ocean sediments (Cehn et al., 1999), and fossil data. Many fossil groups have specific environmental and ecological tolerances and so can be used to determine palaeotemperatures and palaeoclimates (Jones, 2006). It is the data collected using dendroclimatology and other plant macrofossils that will be examined in this article. Dendroclimatology Dendroclimatology is the use of tree rings to determine long-term climatic trends. This is in contrast to dendrochronology, which is dating using tree ring data. Dendroclimatology is used extensity to study the climate during the Holocene (Fig. 1) but has also been applied to the Late Cretaceous of Alaska and even the Permian of Antarctica (Taylor et al., 2009). The thickness of the tree rings helps scientists work out how much the trees had grown within a given year. Then, by comparing the rate of growth to members of the same, or closely related, genera or species, they can determine the palaeoenvironment. Fig. 1. Variations in tree ring width translated into summer temperature anomalies for the last 7,000 years, based on samples from Siberia. Source: Institute of Plant and Animal Ecology https://upload.wikimedia.org/wikipedia/commons/5/53/Yamal50.gif. Dendroclimatology can also be used to gather isotopic data. As … Read More