Scientists now say they could no longer rule out a fast-track melting of the Greenland icesheet — a prospect, once the preserve of doomsayers, that would see much of the world’s coastline drowned by rising seas. The researchers found that the great Laurentide icesheet which smothered much of North America during the last Ice Age melted far swifter than realised, dumping billions of tonnes of water into the ocean.
The discovery raises worrying questions about the future stability of Greenland’s icesheet, for the Laurentide melt occurred thanks to a spurt of warming that could be mirrored once more by the end of this century.
“The word ‘glacial’ used to imply that something was very slow,” said climate researcher Allegra LeGrande of New York’s Columbia University. “This new evidence from the past, paired with our model for predicting future climate, indicates that ‘glacial’ is anything but slow. Past icesheets responded quickly to a changing climate, hinting at the potential for a similar response in the future…”
They built up a map and a timetable for the Laurentide’s retreat and compared this with coral records pointing to Earth’s historic sea levels. They calculate that the Laurentide had two bursts of very fast melting before finally disappearing about 6,500 years ago.
The first phase, around 9,000 years ago, drove up sea levels by around seven metres (22.75 feet), at 1.3 cm (half an inch) each year. The second, around 7,500 years ago, accounted for a rise of five metres (16.25 feet) at the rate of one cm (0.4 of an inch) annually.
The researchers caution that Greenland is an island bathed in chill water, has a somewhat different geology from that of North America, and so the timetable of the Laurentide’s breakup may not exactly apply to it.
Even so, the upper range of the IPCC’s temperature estimates at century’s end are in line with those of the naturally-induced warming that doomed the Laurentide, they said.
“We have never seen an ice sheet retreat significantly or even disappear before, yet this may happen for the Greenland icesheet in the coming centuries to millennia,” said Carlson.
I won’t be around to see the resolution of this discussion. Though, I have no problem with following – and agreeing with – the overwhelming sum of peer-reviewed science.
I get to sit back and laugh at the chuckleheads who revile science as the antichrist in their commitment to ignorance. As if politics somehow will make everything come out alright in the end. People with a Disney-based understanding of history and science.