The tides of the Labrador Sea by transporting, millions of years ago, enormous icebergs originating in the Arctic, would have largely contributed to the various ice ages.

This study, published in Nature magazine in November, is the first to suggest the existence of a link between the tides and the Heinrich events, phenomena reflecting a colossal influx of icebergs from the Arctic there is 60.000 is 10.000 years ago.
The international team, co-led by Professor Jerry Mitrovica, of the Department of Physics at the University of Toronto, showed that the tides, by breaking blocks of ice from the pack ice that then covered northern Canada, contributed greatly to to the cold peaks of the ice ages. This discovery allows us to better understand to what extent the climate can be sensitive to certain factors, such as ocean currents, tides, or sea ice. Ultimately, these data should make it possible to improve climate forecasts.

Computer software has made it possible to date the ancient high tides from a set of information recorded on the tides of the whole world today. The results, valid at 92%, show that the highest tides coincide with the Heinrich events. Researchers are therefore certain of the link between an emergence of icebergs and the tides. However, as Professor Mitrovica points out, these results cannot be directly exploited in the context of the study on climate change which concerns us now. Indeed, if
many factors influence our climate, it is now evident that high tides were a catalyst for major climate change millions of years ago.

contacts:
- Jerry Mitrovica, Department of Physics - tel: +1 (416) 978-4946 - email:
jxm@physics.utoronto.ca
sources: http://www.news.utoronto.ca/bin6/041208-762.asp
Editor: Elodie Pinot, OTTAWA, sciefran@ambafrance-ca.org