Ecologist used paleolimnology to take naturalists ‘back in time’
By Pauline Donaldson
On Thursday November 24th , we hosted the third speaker in our series, “Change in our Natural World”. Guest speaker, Dr. Brian Cumming, is Associate Professor in the Paleoecological Environmental Assessment and Research Laboratory at Queens University (PEARL). The PEARL scientists use techniques of paleolimnology (study of fresh water ecosystems in the past) to provide an historical perspective on environmental change. Data collected is used to determine natural environmental variability in the past, and to test models used to study current global environmental change.
Dr. Cumming’s research can track natural changes in an ecosystem over impressively long time periods (millions of years) in the past, while at the same time uncovering detailed decade by decade information about this time period. Sophisticated sampling techniques and analyses can reveal patterns of temperature, acidity and other changes in a lake over long periods of time. Changes in lake temperature, for example, affect the type of algae and other species which will flourish. These changes can be deduced by analyzing which types of fossil algae are predominant in the lake sediment deposited during a particular time period. Cylindrical cores removed from lake bottom sediment are first calibrated to establish the relationship between depth and timing of deposition (age).
Some of the background work which was done to establish the protocols and the relationships between algal type and the environmental conditions in which they flourished, were done in British Columbia where there is a huge diversity of lake types. This knowledge was then applied when examining sediment cores from lakes in the Canadian Prairies.
From these studies, Dr. Cumming has concluded that abrupt millennial-scale shifts in climate were likely common on the North American continent in the past six thousand years. These natural shifts are more severe and prolonged than the meteorological and historical records indicate. Although the mechanisms behind these changes are unclear, the findings have profound implications for the natural environment and the infrastructures of our communities. Water management plans, for example, may be inadequate if predictions of variations in water availability and water levels are based only on short-term records.
The presentation concluded with many good questions from the audience, followed by refreshments and further discussion. Please join us again in the New Year, on January 19th, when we welcome the fourth guest speaker in the series “Change in our Natural World”. Art Dyke will tell us about “Change in the Arctic”.
