Glacial melting in the West Antarctic Ice Sheet is past the point of no return, NASA has revealed, with research spanning forty years indicating there's now nothing we can do to prevent their demise. The study, carried out in collaboration with the University of California, Irvine, makes ominous predictions about just how significantly the water currently frozen in the ice sheets will contribute to rising sea levels: enough in total, NASA says, to bring the global sea level up by four feet.
That won't happen straight away, of course. "A conservative estimate is it could take several centuries for all of the ice to flow into the sea," Eric Rignot of the Jet Propulsion Lab and UC Irvine said of the research.
However, while it make take some time, there's no stopping it, the study's authors warn. Radar observations made between 1992 and 2011 by the European Earth Remote Sensing satellites were used to map the way so-called grounding lines - the point where the ice rests on stable ground, rather than floating with water in-between - have retreated over time.
Changes in those lines are almost impossible to observe from ground level itself, it's suggested, but can be tracked from space.
The problem - and the reason that scientists are now confident that the melting has "passed the point of no return," according to Rignot - is that the glaciers then rise up and down with tides, increasing the rate at which they melt from the underside. Stopping that from happening can only take place in one way: the glacier getting caught up on a "pinning point", or a jagged bump underneath the ice, which then fixes it in place again.
Problem is, Rignot and his team found, that there are no pinning points to be found upstream from five of the six glaciers melting at unstoppable rates. Already, they release more water into the sea each year than the entire Greenland Ice Sheet, and that process is only going to get faster as warm water from the ocean gets further access to the dwindling glaciers.