LOOMING FLOODS CITIES THREATENED

 

The risk is clear, Antarctica’s collapse has the potential to inundate coastal cities across the globe.

 

Over tens of millions of years, thin layers of snow falling on the continent — in many places, just a light dusting every year — were pressed into ice, burying mountain ranges and building an ice sheet more than two miles thick. Under its own weight, that ice flows downhill in slow-moving streams that eventually drop icebergs into the sea.

If that ice sheet were to disintegrate, it could raise the level of the sea by more than 160 feet — a potential apocalypse, depending on exactly how fast it happened. Recent research suggests that if society burns all the fossil fuels known to exist, the collapse of the ice sheet will become inevitable.

Improbable as such a large rise might sound, something similar may have already happened, and recently enough that it is still lodged in collective memory.

In the 19th century, ethnographers realized that virtually every old civilization had some kind of flood myth in its literature.

In the Epic of Gilgamesh, waters so overwhelm the mortals that the gods grow frightened, too. In India’s version, Lord Vishnu warns a man to take refuge in a boat, carrying seeds. In the Bible, God orders Noah to carry two of every living creature on his ark.

“I don’t think the biblical deluge is just a fairy tale,” said Terence J. Hughes, a retired University of Maine glaciologist living in South Dakota. “I think some kind of major flood happened all over the world, and it left an indelible imprint on the collective memory of mankind that got preserved in these stories.”

That flooding would have occurred at the end of the last ice age.

Ice ages occur when wobbles in Earth’s orbit change the distribution of sunlight, allowing huge ice sheets to build up, mainly in the Northern Hemisphere. At the peak of the last ice age, about 50,000 years ago, the ice sheets grew so large and locked up so much of the world’s water that the sea level fell by an estimated 400 feet.

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