Warm water melting Antarctic ice
Australian researchers have identified how warm water is increasingly pushing out cold water around Antarctica prompting further ice melt and greater sea level rise.
EMMA ALBERICI, PRESENTER: There’s more research tonight pointing to dramatic changes underway in Antarctica. Australian researchers have identified how warm water is increasingly pushing out cold water around the white continent, prompting more ice to melt and further sea level rises. Margot O’Neill with this exclusive report.
MARGOT O’NEILL, REPORTER: Scientists are ringing alarm bells that all is not well on the vast icy southern continent. US glaciologists have already announced that based on satellite data, the collapse of a giant glacier system in West Antarctica is probably irreversible.
Now a team of Australian scientists for the first time have modelled how subsurface ocean temperatures down to 700 metres are rapidly changing around Antarctica. They were shocked by both the size and the speed of what they discovered.
PAUL SPENCE, CLIMATE CHANGE RESEARCH CENTRE, UNSW: Certainly was for me a very frightening result. I didn’t fully appreciate how sensitive this part of the ocean was to change.
MARGOT O’NEILL: Here’s what they found: below the surface of the Great Southern Ocean, a band of cold water at about minus two degrees encircles Antarctica, protecting its icy mass. Beyond that sits another band of water which is up to four degrees warmer. But their research shows that changing wind patterns thought to be partly due to global warming are pushing currents with warm water in and the cold water out.
PAUL SPENCE: And what we find by using projected wind forces for the end of this century is that the warm water tends to just flood onshore right underneath the grounding lines of the glacial ice sheets, the floating ice shelves.
MARGOT O’NEILL: Warm water melts ice much faster than warm air and the research revealed subsurface warming at twice the rate previously thought. That means the melting of West Antarctic ice shelves could be faster than anticipated in the recent UN climate panel report.
PAUL SPENCE: They weren’t considering the types of temperature of warming that we’re seeing in our model simulations around coastal Antarctica. Now just the West Antarctic Ice Sheet, but we also get significant warming of up to four degrees Celsius in regions of the East Antarctic Ice Sheet as well.
MARGOT O’NEILL: Scientists can’t predict when these warm waters will trigger cascading glacial loss.
PAUL SPENCE: It’s not unlike an avalanche of snow where you don’t quite know when it’s going to happen, but when it happens, it can happen quickly.
MARGOT O’NEILL: It now looks like the effects of a transforming Antarctica will be felt this century.
TAS VAN OMMEN, AUSTRALIAN ANTARCTIC DIVISION: We need to bear in mind that even modest sea level rises, half a metre to a metre, is a very big change and if we’re going to see estimates now of several 10ths of a metre more than that by the end of this century, that’s going to rapidly reshape what we need to consider in our response to sea level rise in the future. What’s concerning us is that with a heavily populated planet, it’s going to reshape our coastlines in ways that matter in this century.
MARGOT O’NEILL: The changing face of the White Continent and what it means is now one of most urgent research areas for climate scientists.
Margot O’Neill, Lateline.