Antarctic ice loss has tripled

Antarctica

Antarctic ice loss has tripled

The ice sheet mass balance inter-comparison exercise (IMBIE) is an worldwide effort: a team of 84 polar scientists from 44 organisations, including both of us, working together to provide a single, global record of ice loss from Earth's polar ice sheets. In these five years, Antarctica lost near about two hundred nineteen billion tons of its ice sheet each year. Between 1992 and 2017 we have observed a threefold increase in the rate of ice loss from West Antarctica, from 53 to 159 billion tonnes a year. The main factor behind that gain appears to be fluctuations in snowfall, researchers said.

The most complete analysis to date measuring ice sheet changes in Antarctica reveals Earth's southernmost continent has lost some 3 trillion tonnes of ice over the past quarter-century.

Louisa Casson, from the environmental group Greenpeace UK, said: "Right now we have an opportunity to protect the Antarctic, the incredible home of penguins and whales that also affects our global climate".

Crevasses form on Pine Island Glacier in Antarctica, near the part of the glacier where it leaves land and extends over the ocean.

Satellites contributing to the project include CryoSat, Sentinel-1 and the U.S. "The good news is that limited climate change can slow the rate of ice loss, and there are many proven actions that can reduce climate change and be implemented immediately".

Almost all of the mass shed over the last quarter century has come from West Antarctica, the study found.

More than 70 percent of the recent melt is in West Antarctica.

Ice mass loss is clearly speeding up, driven largely by what's going on in West Antarctica.

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Scientists have long believed the last glacial period, famously known as the Ice Age, ended with a period of continued warming which resulted in the shrinking of ice sheets and an increase in sea levels for thousands of years. The increases are on the order of a few millimetres per year, but scientists need to account for them to ensure their other measures of ice loss are accurate. "But remember for the Northern Hemisphere, for North America, the fact that the location in west Antarctica is where the action is amplifies that rate of sea level rise by up to an about additional 25% in a city like Boston or NY". Ice shelf collapse in the Antarctic Peninsula is another major contributor, whereas less certain estimates of East Antarctica's mass change suggest the region may have gained a negligible amount of ice.

Unlike single-measurement studies, this team looks at ice loss in 24 different ways using 10 to 15 satellites, as well as ground and air measurements and computer simulations, said lead author Andrew Shepherd of the University of Leeds in England. Coastal communities along the USA could feel the impact of a continued increase as melting ice adds to sea level rise, say experts. "We hadn't seen these kinds of structures near the base of an ice sheet before, and the best explanation is that they formed as this portion of the ice sheet re-grounded".

In total, Antarctica stores enough frozen water to lift global sea levels by 58 metres (190ft).

The discovery comes after the global research team, from Australia, the United States and New Zealand, combined satellite images and surface and ocean wave data with modelling, to analyse five major ice shelf disintegrations, between 1995 and 2009.

New and improved satellite missions, such as Sentinel-3, the recently launched Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) and the eagerly awaited ICESat-2, will continue to give researchers more detailed insights into the disappearance of Antarctic ice.

The research also confirms that the land is springing upward due to the ice loss.

Study co-author, Dr Phil Reid, from the Australian Bureau of Meteorology, said the research identified a previously under-appreciated link between sea ice loss and ice shelf stability.

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