Global warming
The melting of ice caps is probably largely underestimated, says a study published this Tuesday, June 25 in the journal “Nature Geoscience”. Because sea water, now warmer due to climate change, is seeping under land ice, accelerating their disappearance.
A point of no return could be about to be reached, tipping Antarctica towards a “uncontrolled melting” of its ice caps, warns a new study, published this Tuesday, June 25 in the journal Nature Geoscience. The melting is caused by now warmer seawater seeping between the ice and the land it sits on.
A climatic tipping point is “a critical threshold beyond which a system reorganizes itself, often abruptly and/or irreversibly”, according to the definition of the UN group of climate experts (IPCC). In other words, a point of no return which leads to cascading consequences, potentially devastating for life on Earth.
The Antarctic ice sheets rest on a rocky layer and extend beyond the coast to float on the sea. Previous studies have already shown that seawater, whose temperature increases under the influence of global warming caused by human activities, could infiltrate into the meeting zone between the land and the sea and thus progress under the terrestrial ice, ever further inland.
The study published this Tuesday confirms this hypothesis and quantifies it. As seawater warms, it opens cavities in the ice, accelerating the intrusion that melts the ice by heating it from below, said the study’s lead author, Alexander Bradley. That “may lead to the exceeding of a tipping point, beyond which ocean water is introduced in an unlimited way under the ice sheet, via a process of uncontrolled melting”says the study.
“Need for urgent climate action”
When accelerated melting outpaces the formation of new ice on the continent, sea levels rise, threatening coastal populations around the world. Problem is, the models used by the IPCC to project the impact of global warming on Antarctica did not take this phenomenon into account. They have also systematically underestimated the ice loss observed so far, points out the study, which believes that these models must be updated.
“This only highlights the need for urgent climate action to prevent these tipping points from being exceeded”, underlines Alexander Bradley, researcher at the British Antarctic Survey. In May, the temperature of the planet’s oceans once again beat, for the 14th month in a row, a new monthly record, reaching an average of 20.93°C, according to the European Copernicus network. “Every tenth of a degree (of warming) brings us closer to this kind of process, these tipping points are getting closer and closer.”alerts the expert again.
