There Is Deep Concern Over The Invisible Threat To Antarctic Glaciers

iceberg-12-13An iceberg floating in the Amundsen Sea, where glaciers are shedding ice faster than in any other part of Antarctica. Image: NASA/Jane Peterson via Wikimedia Commons

As ocean temperatures rise, warmer currents are attacking the Antarctic ice sheet from below and adding to the threats posed by a melting rate that has trebled in the last two decades.

The Antarctic ice shelf is under threat from a silent, invisible agency – and the rate of melting of glaciers has trebled in the last two decades.

The ocean waters of the deep circumpolar current that swirl around the continent have been getting measurably warmer and nearer the ocean surface over the last 40 years, and now they could be accelerating glacier flow by melting the ice from underneath, according to new research.

And a separate study reports that the melting of the West Antarctic glaciers has accelerated threefold in the last 21 years.

Calamitous Consequences

If the West Antarctic ice sheet were to melt altogether – something that is not likely to happen this century – the world’s sea levels would rise by 4.8 metres, with calamitous consequences for seaboard cities and communities everywhere.

Researchers from Germany, Britain, Japan and the US report in Science journal that they base their research on long-term studies of seawater temperature and salinity sampled from the Antarctic continental shelf.

This continued intrusion of warmer waters has accelerated the melting of glaciers in West Antarctica, and there is no indication that the trend is likely to reverse.

Other parts of the continent so far are stable – but they could start melting for the first time.

“The Antarctic ice sheet is a giant water reservoir,” said Karen Heywood, professor of environmental sciences at the University of East Anglia, UK. “The ice cap on the southern continent is on average 2,100 metres thick and contains 70% of the world’s fresh water. If this ice mass were to melt completely, it could raise global sea level by 60 metres. That is not going to happen, but it gives you an idea of how much water is stored there.”

“These waters have warmed . . . and are significantly shallower than 50 years ago”

Temperatures in the warmest waters in the Bellinghausen Sea in West Antarctica have risen from 0.8°C in the 1970s to about 1.2°C in the last few years.

“This might not sound much, but it is a large amount of extra heat available to melt the ice,” said Sunke Schmidtko, an oceanographer at the Geomar Helmholtz Centre for Ocean Research in Kiel, Germany, who led the study. “These waters have warmed in West Antarctica over 50 years. And they are significantly shallower than 50 years ago.”

The apparent rise of warm water, and the observed melting of the West Antarctic ice shelf, could be linked to long-term changes in wind patterns in the southern ocean. Although melting has not yet been observed in other parts of the continent, there could be serious consequences for other ice shelves.

The shelf areas are where the Antarctic krill – the little shrimp that plays a vital role in the Antarctic ocean food chain – are getting warmer, with unpredictable consequences for spawning cycles, and then for ocean biodiversity.

Meanwhile, according to US scientists writing in Geophysical Research Letters, the glaciers of the Amundsen Sea in West Antarctica are shedding ice faster than any other part of the region.

Tyler Sutterley, a climate researcher at the University of California Irvine, and NASA space agency colleagues used four sets of observations to confirm the threefold acceleration.

They took their data from NASA’s Gravity Recovery and Climate Experiment (GRACE) satellites, from a NASA airborne project called Operation IceBridge, from an earlier satellite called ICESat, and from readings by the European Space Agency’s Envisat satellite.

Loss Calculated

The observations spanned the period 1992 to 2013 and enabled the researchers to calculate the total loss of ice, and also the rate of change of that loss.

In all, during that period the continent lost 83 gigatonnes, or 83 billion metric tonnes, of ice per year on average. Since Mount Everest weighs an estimated 161 billion tonnes, this is as if the ice cap lost an Everest’s worth of ice every two years.

After 1992, the rate of loss accelerated by 6.1 billion tonnes a year, and between 2003 and 2009 the melt rate increased by 16.3 gigatonnes a year on average. So the increasing rate of loss is now nearly three times the original figure.

“The mass loss of these glaciers is increasing at an amazing rate,” said Isabella Velicogna, Earth system scientist at both UC Irvine and the NASA Jet Propulsion Laboratory. – Climate News Network

About the Author

Tim Radford, freelance journalistTim Radford is a freelance journalist. He worked for The Guardian for 32 years, becoming (among other things) letters editor, arts editor, literary editor and science editor. He won the Association of British Science Writers award for science writer of the year four times. He served on the UK committee for the International Decade for Natural Disaster Reduction. He has lectured about science and the media in dozens of British and foreign cities. 

Science that Changed the World: The untold story of the other 1960s revolutionBook by this Author:

Science that Changed the World: The untold story of the other 1960s revolution
by Tim Radford.

Click here for more info and/or to order this book on Amazon. (Kindle book)

climate_books

English Afrikaans Arabic Chinese (Simplified) Chinese (Traditional) Dutch Filipino French German Hindi Indonesian Italian Japanese Korean Malay Persian Portuguese Russian Spanish Swahili Swedish Thai Turkish Urdu Vietnamese

LATEST VIDEOS

Jay Inslee Tells Hayes That He Wants To Gut The Filibuster To Fight Climate Change
by MSNBC
Washington Governor Jay Inslee is running for president on the single issue of climate change and argues that doing…
Causes and Effects of Climate Change
by National Geographic
What causes climate change (also known as global warming)? And what are the effects of climate change? Learn the human…
Extreme Weather and Global Warming
by NASA Goddard
Is the frequency of extreme weather events a sign that global warming is gaining pace and exceeding predictions? Bill…
Thanks to Climate Change, Wet Winters No Match for Drier California Summers
by KPIX CBS SF Bay Area
If the emerald-green hills around Northern California have you thinking recent rains have put a damper on the fire…
Climate Change Is Not One Issue
by MSNBC
"Climate change is not one issue," said David Wallace-Wells, author of "The Uninhabitable Earth," but is…
The Heat: Climate change
by CGTN America
Images gathered by NASA show an increase in foliage in China and India. The greening effect is mainly due to ambitious…
No company is doing enough to combat climate change: Jeremy Grantham
by CNBC Television
Jeremy Grantham, co-founder of GMO, on climate change and what needs to be done to combat it.
Power Plants Are POISONING Groundwater All Over America
by The Ring of Fire
According to a new report, 90% of coal-fired power plants across the country have completely contaminated the…

LATEST ARTICLES

Default Image
Come on, UK weather forecasters – tell it like it is on climate change
by Adam Corner
They have a national reach that most climate campaigners would die for. They are familiar and respected experts on the…
Green New Deal: 6 places already reducing emissions from buildings
Green New Deal: 6 places already reducing emissions from buildings
by David Roberts
One of the elements of the Green New Deal resolution that has caused the most consternation among critics on the right…
Default Image
UK environmentalists target Barclays in fossil fuels campaign
by Matthew Taylor
A UK-wide campaign is being launched to persuade one of the country’s biggest high street banks to stop investing…
Oceanic carbon uptake could falter
Oceanic carbon uptake could falter
by Tim Radford
What does oceanic carbon uptake achieve? Greenhouse gas that sinks below the waves slows global warming a little and…
Britain (Yes, Rainy Britain) Could Run Short of Water by 2050, Official Says
Britain (Yes, Rainy Britain) Could Run Short of Water by 2050, Official Says
by Global Warming & Climate Change
“Climate change plus growth equals an existential threat,” Mr. Bevan said. To avoid severe water shortages, he added,…
Default Image
Record high US temperatures outpace record lows two to one, study finds
by Associated Press
Over the past 20 years, Americans have been twice as likely to sweat through record-breaking heat rather than shiver…
Climate change: Water shortages in England 'within 25 years'
Climate change: Water shortages in England 'within 25 years'
by BBC News - Science & Environment
Image copyright PA Image caption Low water levels at Wayoh Reservoir near Bolton in the UK heatwave in July 2018 Within…
Default Image
Why you'll never meet a white supremacist who cares about climate change
by Rebecca Solnit
As the news of the Christchurch mosque massacre broke and I scoured the news, I came across a map showing that the…