Quantifying the Effect of Melting Land Ice on Ocean Currents
27.05.2011 - Water & Oceans, Ice & Snow, Bi-polar
Using a computer climate model to study how freshwater entering the oceans at the end of the penultimate Ice Age 140,000 years ago affected the parts of the ocean currents that control climate, a team of scientists from the University of Sheffield and Bangor University have discovered that freshwater from melting ice sheets can weaken the control of the large-scale ocean circulation over the climate, causing a dramatic climate changes. The study, currently featured in the journal Paleoceanography, is the first of its kind that looks at this period in the Earth's history.
In their study, the scientists noted that global temperatures plummeted by an average of 2°C over a few centuries. These changes, however, were not uniform across the planet, and climate needed a long time to recover after the ice sheets collapsed. At the end of the last ice age 20,000 years ago, the ocean circulation was more sensitive to ice sheet collapses than during the earlier period. The volume of freshwater is not the most important aspect, the team says; the state of the freshwater also determines the magnitude of the changes.
These results, the researchers say, show that future studies of freshwater effects on ocean circulation should take into account the state of the freshwater. A future ice sheet collapse in Greenland or Antarctica would have an impact on the climate, the impact of which would need to be evaluated in each case.