Breaking the ice

Scientists have spent the summer drilling into the Antarctic seafloor to learn from the past what we can expect from future sea level rise.

- VERONIKA MEDUNA

Looking out from the lounge window at Scott Base, you can trace a line where Antarctica's largest ice shelf meets the frozen ocean. Solid waves rise at this juncture between sea ice and the much thicker Ross Ice Shelf, which carries a large part of the outflow from the West Antarctic Ice Sheet (WAIS) hundreds of kilometres out to sea. Where these ice masses come up against the beach outside Scott Base, they buckle into towering, jagged pressure ridges.

But some 1200km south from Scott Base, at the continental edge of the WAIS where it lifts off the ground to become the floating Ross Ice Shelf, the view is very different. In every direction, it expands endlessly across the flat, smooth, snow-covered ice. Sometimes, when clouds descend low, the horizon line between the greys of the ice and the sky becomes barely distinguishable.

This is where one of the most ambitious Antarctic research projects has set up camp for its first season this summer. SWAIS2C - short for Sensitivity of the West Antarctic Ice Sheet to 2°C-is an international collaboration aiming to decipher how the WAIS reacted to warming in the past, including during the last interglacial period some 125,000 years ago when Earth was about 1.5°C warmer than pre-industrial temperatures - similar to the target set in the Paris Agreement.

"Glaciologists have been suggesting for a long time that we're going to lose the ice sheet if we exceed 1 or 1.5 degrees," says Richard Levy, a geologist at GNS Science and Victoria University of Wellington/ Te Herenga Waka and a co-leader of the SWAIS2C project.