A 128 metre wide waterfall spans the Nansen ice shelf- billions of tonnes of ice are being lost annually. (Wong Sang Lee/Korea Polar Research Institute)

Antarctica- melting tripled to billions of tonnes annually

Two new and separate international studies show serious concerns about Antarctic ice.

One international study showed vastly increased melting in the billions of tonnes, while the other Canadian led study showed the massive ice shelves were being undermined by warming ocean currents.

“We are learning that ice shelves are more vulnerable to rising ocean and air temperatures than we thought. There are dual processes going on here. One that is destabilizing from below, and another from above. This information could have an impact on our projected timelines for ice shelf collapse and resulting sea level rise due to climate change.” Christine Dow, University of Waterloo, Ontario

The melting study known as the “Ice Sheet Mass Balance Inter-comparison Exercise” (IMBIE) by 80 Antarctic experts from 14 countries and led by the University of Leeds in the U.K. showed melting rates tripling in the past decade.

The report published in the journal Nature this week is called

Mass balance of the Antarctic Ice Sheet from 1992 to 2017” (abstract HERE)

Video (YouTube) U Waterloo (no sound)

They collectively reviewed data from 1992 and also examined 24 recent measurements obtained by different methods to reach consensus of figures

RCI- Dec 2017: Arctic ice melt-highest melt in 1,500 years

It showed that from 1992 to 1997, ice loss from Antarctica was 49 billion tonnes annually, in the 2000’s ice loss increased to 73 billion tonnes, while from 2012 through to 2017, that rate had increased dramatically to 219 billion tonnes annually. It shows most of the melting occurring in West Antarctica with lesser melting in East Antarctica and greater variations in reliable figures.

It also shows however that the ice loss is contributing to a sea level rise of between approximately 7.6mm

Another two-year international study was led by Canada Research Chair Christine Dow of the University of Waterloo’s Faculty of Environment.

Christine Dow, Canada Research Chair and assistant professor at the University of Waterloo’s Faculty of Environment on the Carnein Glacier, feeding into Nansen Ice Shelf, East Antarctica.

It found that warming currents were eroding the enormous ice-shelves from below creating cracks in the shelf. In turn meltwater flowing into the cracks further weakened the shelf from above increasing the chance of major calving  such as that in 2000 when an 11,000 km piece of the Ross ice shelf broke off, and another in July 2017 when another piece over 5,500 square kilometres broke from the Larsen C ice shelf, and two other huge icebergs (153sq/km and 61 sq/km) calved from the Nansen shelf. Other enormous calving events have also occurred in recent years.

Nansen Ice Shelf fracture six months prior to breaking off in 2016. ( C Dow et al)

The Waterloo study called Basal channels drive active surface hydrology and transverse ice shelf fracture was also published this week in the journal AAAS Science Advances ( open access HERE)

The study shows that these basal thinning and cracks are occurring at most of the ice shelves in the Antarctic and in Greenland.

The ice shelves control the moving of land based glaciers, and as the shelves lose mass, the glaciers themselves could speed up further increasing ice loss and sea-level rise.

As more data is developed, scientists say it only adds increased urgency to efforts to mitigate greenhouse gasses and subsequent warming and climate change.

Additional information

Categories: Environment & Animal Life, International, Internet, Science & Technology
Tags: , , ,

Do you want to report an error or a typo? Click here!

For reasons beyond our control, and for an undetermined period of time, our comment section is now closed. However, our social networks remain open to your contributions.