DATING THE PAST
Prof. Frank Oldfield
University of Liverpool
What we learn from the past can help us make sensible decisions about the future.
Dating the past, measuring past environmental parameters, whether over a few
decades or thousands of years, can provide us with information on how our climate
and our ecosystems have changed. Sometimes this information gives us clues as to
why species and even societies emerge, flourish and then disappear. Explaining how
to collect and use information from the past was the task undertaken by Prof. Frank
Oldfield, University of Liverpool, in his talk to the joint meeting of the Cirencester
Science and Technology and the Cirencester Archaeological and Historical Societies
in November.
What are the tools that enable us to date the past? We are all familiar with tree rings
and how the year by year growth of a tree can be measured and compared with
changes in the local environment. But there are many more tools at our disposal:
coral reefs can provide data season by season; lake sediment cores are a store of
information on past floods, droughts, agricultural and human activity; Carbon 14
dating techniques applied, for example, to gas bubbles trapped in the Antarctica ice
sheet give a frozen record of the levels of atmospheric carbon dioxide and methane
present in past climates going back thousands of years. In many cases it is possible
to correlate past environmental changes with human activity, major volcanic eruptions
or even small changes in the orbital relationship between the Sun and Earth. These
different dating techniques provide detailed views of past climates and environments
for times and places where no written records exist.
Recent technological advances have improved dramatically the accuracy of dating
methods: sample sizes in the case of Carbon 14 dating are now only a fraction of a
gram. Interest in the techniques is increasing as concerns over global warming and
environmental issues grow. The past it seems may hold the key to ensuring a
sustainable future for our planet.
Given on 23 November 2005 at the Royal Agricultural College, Cirencester.