The Guardian view on an ice-sheet collapse: threatening the world’s coasts

 Opinion

Extract from The Guardian

Climate change

Editorial

A scientific expedition to Thwaites glacier aims to provide vital information about the dangers of melting Antarctic ice

Wed 8 Jan 2020 05.32 AEDT Last modified on Wed 8 Jan 2020 06.05 AEDT

The Thwaites glacier in West Antarctica. ‘The rate of Thwaites’s disintegration has alarmed scientists for good reason.’ Photograph: US National Science Foundation/PA

Thwaites glacier, a vast river of ice the size of Great Britain, holds enough frozen water that were it to collapse, the world’s oceans would rise by more than 60cm. Part of the West Antarctic ice sheet, it is one of the most unstable glaciers on the continent. Since the 1980s, Thwaites has lost 540bn tonnes of ice into the dark waters of the Amundsen Sea. This single glacier is responsible for 4% of global sea level rise.
The rate of Thwaites’s disintegration has alarmed scientists for good reason. In a handful of decades it could retreat to the point that collapse becomes inevitable and irreversible. That would lock us into a future sea level rise of far more than half a metre or so. The reason is simple: today, Thwaites is a brake on large inland glaciers. Lose Thwaites, and those it holds back will follow. Over centuries perhaps, they would add fully 2m to sea level rise.

Nearly 100 scientists and support staff recently arrived at Thwaites, a place as inhospitable as Earth can muster, for an urgent and ambitious field expedition. Among the British and American teams are scientists, engineers and technicians who have set up tents on Thwaites ice shelf, the slab of glacier that has slipped off the Antarctic bedrock on to the sea. They have now set up a hot water drill to bore through the 600m shelf into the frigid waters beneath. It is a process that takes days, with small teams working nonstop around the clock.

Why drill down? With the borehole open, the researchers will winch down a torpedo-shaped robotic submarine called Icefin. It will slip into the depths and make for the grounding line, where the base of the glacier lifts off the land. There it will inspect a grim discovery that Nasa scientists made some months back. Flying over the glacier on a plane fitted with ice-penetrating radar, they spotted a gigantic hole at the base of Thwaites. At 4km wide and 10km long, it is two-thirds the area of Manhattan. The 350m-tall cavern formed over three years when 13bn tonnes of ice melted away. Water had found its way between the glacier’s rough base and the bedrock to melt it, unnoticed, from below. Thwaites will surely now deteriorate faster.

It is a stark reminder that for all the observations and sophisticated climate models that scientists produce, nature can still serve up unwelcome surprises. The fact is that we are ill-equipped to model precisely a global system as devilishly complex as the climate. If we don’t know every detail – every process, every threshold, and the direction and strength of every feedback loop – we must always expect surprises. This might be the lesson of Thwaites glacier. In both the US and the UK – the countries behind the expedition – science is in peril. The Royal Society warns that Britain is losing top scientists amid ongoing Brexit uncertainty. In the US, the administration has set itself against science, particularly in environmental disciplines, and scores of researchers have quit their posts. If Thwaites tells us anything, it is that we need more science, not less, to survive the climate crisis. Without it, we will not understand the full threat we face, nor be well placed to mitigate its most dangerous consequences. If we want to avoid more unwelcome surprises, we must not let our guard down.