SOURCE: The Conversation

DATE: November 6, 2019

SNIP: Sea levels rose 10 metres above present levels during Earth’s last warm period 125,000 years ago, according to new research that offers a glimpse of what may happen under our current climate change trajectory.

Our paper, published today in Nature Communications, shows that melting ice from Antarctica was the main driver of sea level rise in the last interglacial period, which lasted about 10,000 years.

This research shows that Antarctica, long thought to be the “sleeping giant” of sea level rise, is actually a key player. Its ice sheets can change quickly, and in ways that could have huge implications for coastal communities and infrastructure in future.

Earth’s cycles consist of both cold glacial periods – or ice ages – when large parts of the world are covered in large ice sheets, and warmer interglacial periods when the ice thaws and sea levels rise.

The Earth is presently in an interglacial period which began about 10,000 years ago. But greenhouse gas emissions over the past 200 years have caused climate changes that are faster and more extreme than experienced during the last interglacial. This means past rates of sea level rise provide only low-end predictions of what might happen in future.

We examined data from the last interglacial, which occurred 125,000 to 118,000 years ago. Temperatures were up to 1℃ higher than today – similar to those projected for the near future.

Our research reveals that ice melt in the last interglacial period caused global seas to rise about 10 metres above the present level. The ice melted first in Antarctica, then a few thousand years later in Greenland.

Sea levels rose at up to 3 metres per century, far exceeding the roughly 0.3-metre rise observed over the past 150 years.

The early ice loss in Antarctica occurred when the Southern Ocean warmed at the start of the interglacial. This meltwater changed the way Earth’s oceans circulated, which caused warming in the northern polar region and triggered ice melt in Greenland.