The second lesson from our work may bring some hope. Some 5,000 years ago the ice sheet margin stopped retreating in most locations, and in some regions actually started to advance. One explanation for this relates to the previous period of ice loss.
Before the ice began melting away, the Antarctic ice sheet was much heavier, and its weight pushed down into the Earth’s crust (which sits atop a molten interior). As the ice sheet melted and became lighter, the land beneath it would have lifted up – effectively hauling the ice out of the ocean.
Another possible explanation is climate change. At Antarctica’s coastal fringe, the ocean may have temporarily switched from warmer to cooler waters around the time the ice sheet began advancing again. At the same time, more snowfall took place at the top of the ice sheet.
Our research supports the idea that the Antarctic ice sheet is poised to lose more ice and raise sea levels – particularly if the ocean continues to warm.
It also suggests uplift of the land and increased snowfall have the potential to slow or offset ice loss. However, this effect is not certain.
The past can never be a perfect test for the future. And considering the planet is warming faster now than it was back then, we must err on the side of caution.
This article is republished from The Conversation under a Creative Commons License.