We now know how much ice Antarctica has lost in the last 25 years – three trillion tonnes


Antarctica’s ice sheet is melting at a rapidly increasing rate, according to a new report by a team of 80 scientists who have analyzed satellite imagery of the region.

Antarctica is the largest ice sheet on Earth and almost 220 billion tonnes of it is melting into the ocean each year. That is pushing up global sea levels by 0.6mm annually, a three-fold increase since the last assessment in 2012.

The speed that the ice melts is a key indicator of climate change. And it has grave implications for low-lying countries such as the Solomon Islands and the Maldives, suggesting they have less time to construct future defences against the rising ocean.

Warmer waters

The study – known as the Ice Sheet Mass Balance Inter-Comparison Exercise – is the compilation of recent measurements of Antarctic ice loss, using satellite imagery to assess the height and weight of the ice, as well as the speed that it is moving towards the water.

The differences between the studies are reconciled to produce the most definitive possible set of data. The Imbie study is led by Andrew Shepherd, Professor of Earth Observation and Director of the NERC Centre for Polar Observation and Modelling.

“What we can say is that it’s too warm for Antarctica today. It’s about half a degree Celsius warmer than the continent can withstand and it’s melting about five metres of ice from its base each year, and that’s what’s triggering the sea-level contribution that we’re seeing,” he told BBC News .

Rising sea levels are a particular concern to areas of high population density in coastal areas, where sea levels play a role in flooding and shoreline erosion. It also means that storms cause more damage as surges of water push further inland than they have done previously.

Greenhouse gas emissions and global warming are the main causes of rising sea levels. Almost 200 countries agreed on the need to cut greenhouse gas emissions at the signing of the Paris climate agreement, and committed to keeping global temperatures ‘well below’ 2°C above pre-industrial times.

Strong compliance with the Paris Agreement is one way of helping control the speed of the melting of the Antarctic ice sheet.

Jahda Swanborough, Lead, Environmental Initiatives at the World Economic Forum, said: “News that the world’s largest ice sheet is melting more rapidly is a loud wake-up call. This is a classic example of a global commons challenge – the consequences of a melting Antarctic ice sheet have the potential to affect most people on the planet. We share responsibility for our climate system and need to increase our collective climate ambition.”

SOURCE: World Economic Forum

By Briony Harris
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