Melting glaciers, ice sheets, raising Earth's seas

PARIS - As the planet's polar ice sheets destabilize amid rising temperatures, a landmark UN assessment of Earth's retreating frozen spaces is also set to spell out how melting mountain glaciers will impact humanity in the decades to come.

AFP has obtained an official draft summary of the forthcoming Intergovernmental Panel on Climate Change's (IPCC) report on oceans and the cryosphere.

It says that the Greenland and Antarctic ice sheets lost roughly 400 billion tons of mass annually in the decade to 2015, corresponding to a sea-level rise of around 1.2 millimeters each year.

But glaciers high up mountains also lost around 280 billion tons of ice each year during the same period, raising seas a further 0.77 millimeters annually.

"In the past 100 years, 35 percent of global sea-level rises came from glacier melting," Anders Levermann, climate professor at the Potsdam Institute for Climate Change Impact, told AFP. 

He said that future sea-level rises from glacial melt alone would be limited to 30 to 50 centimeters as they contain a limited amount of ice. 

By comparison, there's enough frozen water in the Greenland and Antarctic ice sheets to lift global sea levels several dozen meters.

"(Melting glaciers) contribute significantly to sea-level rise, it's just not this huge number that Greenland and Antarctica could contribute," added Levermann, who was not involved in the IPCC report.

There are roughly 200,000 glaciers -- vast, ancient reserves of ice -- on Earth and their relative smallness compared to the polar ice sheets makes them especially vulnerable to rising temperatures.

Their retreat is likely to impact inland communities the world over, for whom glaciers are a key water source.

The glaciers nestled high in the Himalayas provide water for 250 million people in nearby valleys and feed the rivers upon which a further 1.65 billion people rely for food, energy and income.

One study referenced in the IPCC report warns that Asian high mountain glaciers could lose more than a third of their ice, even if humans slash greenhouse gas emissions and limit global warming to 1.5 degrees Celsius.

A continuation of "business-as-usual" in the coming decades with a global economy still powered mainly by fossil fuels could see two-thirds lost.

"Drinking water is going to be affected, agriculture is going to be affected and we are talking about millions and millions of people," said Harjeet Singh, international climate lead at ActionAid. 

The IPCC summary said that areas of the central and western Himalayas are already facing a noticeable fall in water for irrigation.

'A glacier is a reservoir'

The summary also warned that in regions with little ice cover, including Central Europe, North Asia and Scandinavia, glaciers were projected to shrink 80 percent by 2100.

One study this year by scientists in Switzerland warned that unchecked emissions could see more than 90 percent of Alpine glaciers disappear by century's end.

Harry Zekollari, from Delft University of Technology in the Netherlands, said most people did not appreciate how crucial the giant ice structures were.

"A glacier is a reservoir. A healthy glacier will typically melt in summer and become a bit bigger in winter. That means that when people need water most, they get water from the glacier," Zekollari told AFP.

'Fighting for water'

Melting glaciers also have other human impacts. 

The citizens of La Paz, Bolivia's administrative capital, get as much as 30 percent of their water from Andean glaciers during the dry winter months.

In 2016, the city ran dry.

"About 100 neighborhoods were without any water for more than a month, it was like a horror movie from the future," Marcos Andrade, director of the Laboratory of Atmospheric Physics at San Andres University, told AFP. 

"People were fighting for their water."

Despite this stark example of what can happen when glacial water supply is disrupted, Andrade said there was a paradox in explaining how melting glaciers are bad news for agriculture.

"We have now more water from the glaciers because they are melting and farmers maybe don't realize that," he said. 

"Things are going better for them at the moment. But once the water reaches a peak it will be scarce and it's going to be something we are probably going to fight over." 

The IPCC says glacier runoff is likely to continue to increase in the short term before declining late century, bringing increased instability and more landslides, avalanches and more polluted water.

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Iceland commemorates first glacier lost to climate change

REYKJAVIK - Iceland on Sunday honored the passing of Okjokull, its first glacier lost to climate change, as scientists warn that some 400 others on the subarctic island risk the same fate. 

As the world recently marked the warmest July ever on record, a bronze plaque was mounted on a bare rock in a ceremony on the former glacier in western Iceland, attended by local researchers and their peers at Rice University in the United States who initiated the project. 

Iceland's Prime Minister Katrin Jakobsdottir and former United Nations High Commissioner for Human Rights Mary Robinson also attended the event, as well as hundreds of scientists, journalists and members of the public who trekked to the site.

"I hope this ceremony will be an inspiration not only to us here in Iceland but also for the rest of the world, because what we are seeing here is just one face of the climate crisis," Jakobsdottir told AFP.

The plaque bears the inscription "A letter to the future", and is intended to raise awareness about the decline of glaciers and the effects of climate change.

"In the next 200 years all our glaciers are expected to follow the same path. This monument is to acknowledge that we know what is happening and what needs to be done. Only you know if we did it," the plaque reads.

It is also labelled "415 ppm CO2", referring to the record level of carbon dioxide measured in the atmosphere last May.

The plaque is "the first monument to a glacier lost to climate change anywhere in the world", Cymene Howe, associate professor of anthropology at Rice University, said in July.

"Memorials everywhere stand for either human accomplishments, like the deeds of historic figures, or the losses and deaths we recognize as important," she said.

"By memorializing a fallen glacier, we want to emphasize what is being lost -- or dying -- the world over, and also draw attention to the fact that this is something that humans have 'accomplished', although it is not something we should be proud of."

Howe noted that the conversation about climate change can be abstract, with many dire statistics and sophisticated scientific models that can feel incomprehensible.

"Perhaps a monument to a lost glacier is a better way to fully grasp what we now face," she said, highlighting "the power of symbols and ceremony to provoke feelings".

'Pretty visual'

Julien Weiss, an aerodynamics professor at the University of Berlin who attended Sunday's ceremony with his wife and seven-year-old daughter, was one of those moved by seeing the ex-glacier Sunday.

"Seeing a glacier disappear is something you can feel, you can understand it and it's pretty visual," he told AFP.

"You don't feel climate change daily, it's something that happens very slowly on a human scale, but very quickly on a geological scale."

Iceland loses about 11 billion tonnes of ice per year, and scientists fear all of the island's 400-plus glaciers will be gone by 2200, according to Howe.

Glaciers cover about 11 percent of the country's surface.

"A big part of our renewable energy is produced in the glacial rivers.... The disappearance of the glaciers will affect our energy system," Prime Minister Jakobsdottir said.

Stripped in 2014 

Glaciologists stripped Okjokull of its glacier status in 2014, a first for Iceland.

In 1890, the glacier ice covered 16 square kilometers (6.2 square miles) but by 2012, it measured just 0.7 square kilometers, according to a report from the University of Iceland from 2017.

In 2014, "we made the decision that this was no longer a living glacier, it was only dead ice, it was not moving," Oddur Sigurdsson, a glaciologist with the Icelandic Meteorological Office, told AFP.

To have the status of a glacier, the mass of ice and snow must be thick enough to move by its own weight. For that to happen the mass must be approximately 40 to 50 meters (130 to 165 feet) thick, he said.

According to a study published by the International Union for Conservation of Nature (IUCN) in April, nearly half of the world's heritage sites could lose their glaciers by 2100 if greenhouse gas emissions continue at the current rate. 

source: news.abs-cbn.com

Melting Antarctic glaciers to raise seas, study warns

OSLO - Vast glaciers in West Antarctica seem to be locked in an irreversible thaw linked to global warming that may push up sea levels for centuries, scientists said on Monday.

Six glaciers, eaten away from below by a warming of sea waters around the frozen continent, were flowing fast into the Amundsen Sea, according to the report based partly on satellite radar measurements from 1992 to 2011.

Evidence shows "a large sector of the West Antarctic ice sheet has gone into a state of irreversible retreat", said lead author Eric Rignot of the University of California, Irvine, and NASA's Jet Propulsion Laboratory in Pasadena, California.

The coastal ends of the glaciers rest on bedrock below sea level, holding back a vast weight of ice and making them vulnerable to melt, he said. He likened the process to uncorking a full bottle of wine while it was lying on its side.

This part of Antarctica would be a major contributor to sea level rise in coming decades and centuries since the glaciers hold enough ice to raise sea levels by 1.2 metres (4 feet).

"It's passed the point of no return," he told a telephone news conference.

Ice-penetrating radars showed no mountain ranges entombed under the ice, for instance, that could halt the flow. The fastest retreat was 34-37 km (21-23 miles) over the period in the Smith/Kohler glacier.

Even so, cuts in greenhouse gas emissions, part of efforts to rein in global warming, could at least slow the slide of the Pine Island, Thwaites, Haynes, Pope, Smith and Kohler glaciers.

"We do think this is related to climate warming," Rignot said. The scientists believed that a build-up of man-made greenhouse gases in the atmosphere was affecting wind patterns around Antarctica, driving warmer waters towards the continent.

Almost 200 nations have agreed to work out a U.N. pact by the end of 2015 to combat global warming, which the U.N. Intergovernmental Panel on Climate Change (IPCC) says will cause more floods, droughts, heat waves and higher seas.

SEA LEVELS

Monday's findings may also mean that scenarios by the IPCC for sea level rise are too low. The IPCC said last year that sea levels are likely to rise by between 26 and 82 cm (10 and 32 inches) by the late 21st century, after a 19 cm (7 inch) rise since 1900.

"The major ice sheets of this planet will have a larger and larger role in sea level rise in the decades ahead," said Sridhar Anandakrishnan, professor of geosciences at Pennsylvania State University, who was not involved in the study.

Last week, another study also suggested a part of the far bigger ice sheet in East Antarctica may also be more vulnerable than expected to thaw. The IPCC says it is at least 95 percent probable that warming is caused by human activities, led by the burning of fossil fuels.

Monday's study, to be published in the journal Geophysical Research Letters, adds to signs of climate change under way.

On May 6, the Obama administration issued a study saying that warming "once considered an issue for a distant future has moved firmly into the present."

And the IPCC said in March there were signs of irreversible changes to tropical coral reefs and to the Arctic.

A separate study of the Thwaites glacier by the University of Washington in the journal Science also said it may have begun an unstoppable collapse that could last from 200 to 1,000 years.

A disappearance of the Thwaites alone would raise world sea levels by 60 cm (1.96 feet) but the "glacier also acts as a linchpin on the rest of the ice sheet, which contains enough ice to cause another three to four metres of sea level rise", it said.

The findings contrast with a paradoxical expansion of the extent of ice floating on the sea around Antarctica in recent winters that the scientists said may be part of natural variations. "The changes in the glacier reflect much longer-term processes," Tom Wagner, a scientist with NASA's Science Mission Directorate in Washington, said in the telephone briefing. (Editing by Mark Heinrich)

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