Dramatic Ice Sheet Collapse Triggered Global Climate Change in the Past

An ice sheet collapse may just trigger climate change--just like it did in the past. Researchers have taken a closer look at past climatic events and have found that a dramatic ice sheet collapse about 135,000 years ago may have helped caused widespread climate change.

"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 Gianluca Marino, leader of the new study, in a news release. "Ice-ages may superficially look similar to one another, but there are important differences in the relationships between the melting of continental ice sheets and global climate changes. During the major climate warmings ending an ice age, periods of slower change alternated with periods of faster change, but it was unclear if these alternations were always the same at the end of every ice age."

In this latest study, the researchers examined precisely dated cave records. This allowed them to reconstruct the sequence through time of changes in all critical climate parameters.

"At the end of the last ice age, rapidly melting of the Northern Hemisphere ice sheets and major climate changes did not occur at the same time," said Eelco Rohling, one of the researchers. "At the end of the ice-age before last, 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. The North Atlantic cooled while the Southern Ocean warmed. The latter destabilized Antarctic land ice, causing a continuation of melting that eventually drove sea level rise to several meters above the present."

The findings reveal a bit more about how climate is impacted by melting ice and ocean currents. Currently, the Southern Ocean is warming, and the researchers believe that they can use data from the past in order to find out what effects this may have on the global environment.

The findings are published in the journal Nature.

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