Dramatic ice sheet collapse triggered global climate change

Scientists from the University of Southampton have found that the climatic events that ended the earlier ice age are surprisingly different to those of the last ice age.

At the end of an ice age continental ice sheets, oceans and atmosphere change rapidly.

These results will help scientists understand the processes that control Earth's dramatic climate changes at the end of an ice age.

"To our surprise, the sequence of climate events 135,000 years ago looks very different from what happened at the end of the last ice age, about 20,000 to 10,000 years ago," said lead author Gianluca Marino of Australian National University (ANU).

Scientists have previously only been able to reconstruct in detail the changes at the end of the last ice age.

"At the end of the last ice age, rapid melting of the Northern Hemisphere ice sheets and major climate changes did not occur at the same time. At the end of the ice age, 135,000 years ago, a rapid collapse of the Northern Hemisphere ice sheets into the North Atlantic Ocean suppressed ocean circulation and caused global climate impacts," said co-author professor Eelco Rohling from the University of Southampton.

Scientists had previously only been able to reconstruct in detail the changes at the end of the last ice age.

"The North Atlantic cooled while the Southern Ocean warmed. The latter destabilised Antarctic land ice, causing a continuation of melting that eventually drove sea level rise to several metres above the present," Rohling said.

By using precisely dated cave records and marine sediments from the Mediterranean region, the team reconstructed the sequence through time of changes in all critical climate parameters.

The study appeared in the journal Nature.