Wednesday, 18 July, 2018

Antarctic ice melting faster than previously thought

Andrew Shepherd shows an unusual iceberg near the Rothera Research Station on the Antarctic Peninsula. In a study released Wednesday Antarctic ice melting faster than previously thought
Theresa Hayes | 17 June, 2018, 10:38

Antarctica has lost 84 billion tonnes of ice each year from 1992 till 2011.

For the past five years the rate of ice loss has tripled to up to 30% of all sea level rise and that makes us not too concerned about sea level rise today, but will in the near future.

They also highlight the existential threat facing low-lying coastal cities and communities home to hundreds of millions of people.

"The ice sheet is now losing three times as much ice".

"We view these results as another ringing alarm for action to slow the warming of our planet".

That's because as Antarctica's mass shrinks, the ice sheet's gravitational pull on the ocean relaxes somewhat, and the seas travel back across the globe to pile up far away - with USA coasts being one prime destination.

This latest IMBIE is the most complete assessment of Antarctic ice mass changes to date, combining 24 satellite surveys of Antarctica and involving 80 scientists from 42 worldwide organizations.

The Antarctic Ice Sheet covers an area of about 14 million square kilometres; by comparison, the area of Australia is about 7.7 million square kilometres, and that of the United States of America is about 9.8 million square kilometres.

Benjamin Smith, senior principal investigator at the University of Washington Applied Physics Laboratory, said climate scientists are getting a better handle on crucial questions relating to the impact of Antarctic melting, thanks to more advanced satellites.

Hamish Pritchard summer clouds swirl around the Staccato Peaks of Alexander Island off the Antarctic Peninsula. In a study released Wednesday

In contrast, the global consequences set out under the high emissions narrative include dramatic loss of major ice shelves, sea warming, sea ice retreat and ocean acidification, and degradation of the environment caused by unrestricted growth in human use of Antarctica and introduced invasive pests.

Already floating, ice shelves breaking off into icebergs do not add to sea level. According to scientists, this water is enough to cover Texas to a calculated depth of 13 feet. Most of this came from the acceleration of the huge Pine Island and Thwaites Glaciers.

While that won't happen overnight, Antarctica is indeed melting, and a study published on Wednesday in the journal Nature shows that the melting is speeding up. The finding could have significant implications for global sea level rise.

The study, by an worldwide team of polar scientists led by Canada Research Chair Christine Dow of Waterloo's Faculty of Environment, discovered that the process of warmer ocean water destabilizing ice shelves from below is also cracking them apart from above, increasing the chance they'll break off.

"A lot of the argument has been made by stakeholders that are not quite as interested in dealing with climate change that the East Antarctic ice sheet is actually gaining mass - therefore we don't need to worry", said Ms Michele Koppes, a glaciologist at the University of British Columbia, Canada.

Oceans are now rising by 3.4 millimetres (0.13 inches) per year.

Under any scenario, oceans will continue to rise for several centuries, scientists say. It shows that before 2012, the Antarctic lost ice at a steady rate of 76bn tonnes per year - a 0.2mm per year contribution to sea-level rise. Back in 2012, when the previous study was done, that figure was 76 billion tonnes.

Prof Andrew Shepherd, from Leeds University and a lead author of the study on accelerating ice loss, said: "We have long suspected that changes in Earth's climate will affect the polar ice sheets".