Glaciers naturally flow but thinning is alarming

From an Article by Brett Wilkins, The Guardian UK, 4/28/21

Researchers warn of the need for urgent climate action as a study published Wednesday revealed that the world’s mountain glaciers are melting at an unprecedented pace, with glacial thinning rates outside Antarctica and Greenland doubling this century. “A doubling of the thinning rates in 20 years for glaciers outside Greenland and Antarctica tells us we need to change the way we live,” the study’s lead author said.

For the first time ever, researchers analyzed three-dimensional satellite measurements of the world’s approximately 220,000 glaciers, except for those on the Antarctic and Greenland ice sheets. The results, published in Nature, show that the planet’s glaciers lost 267 billion tonnes of ice each year from 2000 to 2019, the equivalent of 21% of sea level rise. The study’s authors said that is enough water to flood all of Switzerland under six feet of water every year.

The paper notes that “thinning rates of glaciers outside ice sheet peripheries doubled over the past two decades.” The study’s authors found that, on average, glaciers lost 4% of their volume during the two decades studied. They determined that the fastest-melting glaciers are in Alaska and the Alps. Alaska alone accounted for one-quarter of the world’s glacial melt, with the Columbia Glacier in Prince William Sound retreating by around 115 feet annually.

“A doubling of the thinning rates in 20 years for glaciers outside Greenland and Antarctica tells us we need to change the way we live,” Romain Hugonnet of the University of Toulouse in France, the study’s lead author, told The Guardian.

“It can be difficult to get the public to understand why glaciers are important because they seem so remote,” he added, “but they affect many things in the global water cycle including regional hydrology, and by changing too rapidly, can lead to the alteration or collapse of downstream ecosystems.”

Hugonnet said he was particularly concerned about glacier loss in high Asian mountain ranges, which are the sources of rivers upon which more than 1.5 billion people rely for water. “India and China are depleting underground sources and relying on river water, which substantially originates from glaciers during times of drought,” he told The Guardian.

“This will be fine for a few decades because glaciers will keep melting and provide more river runoff, which acts as a buffer to protect populations from water stress,” said Hugonnet. “But after these decades, the situation could go downhill. If we do not plan ahead, there could be a crisis for water and food, affecting the most vulnerable.”

Mark Serreze, director of the Colorado-based National Snow and Ice Data Center, told the Associated Press that sea level rise—which is exacerbated by glacier melt—”is going to be a bigger and bigger problem as we move through the 21st century.” Serreze did not contribute to the new paper.

The new study’s authors implore policymakers to devise adaptive measures for the estimated billion people threatened with water and food insecurity before 2050. “We need to act now,” stressed Hugonnet.

Samuel Nussbaumer of the World Glacier Monitoring Service, which did not take part in the study, said that “the new paper will have a big impact.”

“This is the most global, complete study. The gain in new information is huge,” Nussbaumer told The Guardian. “The rapid change we see now is really interesting from a scientific point of view. Never before in history has change happened this fast.”

The new study follows research published last week showing shifts in the Earth’s rotational axis—which have accelerated over the past three decades—are caused by melting glaciers.

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“If we do not plan ahead, there could be a crisis for water and food, affecting the most vulnerable.” —Romain Hugonnet, University of Toulouse

“Never before in history has change happened this fast.” —Samuel Nussbaumer, World Glacier Monitoring Service

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See also: Global Ice Loss on Pace to Drive Worst-Case Sea Level Rise, Bob Berwyn, Inside Climate News, January 25, 2021

A new study combines ice melt data from all sources to reaffirm one of the most serious climate change threats.

Greenland ice sheets melting more rapidly

Interview of Michael Oppenheimer by Steve Curwood of Living on Earth, October 23, 2020

The Antarctic and Greenland ice sheets are melting at alarming rates thanks to climate change, and will continue to do so for decades even if the Paris Climate Agreement goals are met. Host Steve Curwood speaks with Princeton University climate scientist Michael Oppenheimer about how these massive ice sheets contribute to global sea level rise, and why their melting necessitates both the reduction of global warming gases and adaptation to protect vulnerable coasts.

Transcript of Interview Available Here

As the planet continues to warm, the ice of Antarctica and Greenland melts faster and faster, adding to sea level rise. Scientists say even if the Paris Climate Agreement goals are met, melting from the West Antarctic ice sheet alone could raise the oceans some eight feet by the end of the century. Sooner than that, in less than 30 years, the ice losses from Antarctica, combined with the rapid melting of Greenland are projected to elevate the seas one if not two feet. And that doesn’t factor in the impacts of thermal expansion of water already in the ocean and the melting of mountain glaciers. Here to discuss the latest research is Michael Oppenheimer, Professor of Geosciences and International Affairs at Princeton University. Michael Oppenheimer, welcome to Living on Earth!

CURWOOD: Walk me through the science behind the melting of the Antarctic and Greenland ice sheets. What’s going on?

OPPENHEIMER: First of all, let’s understand what an ice sheet is and how it forms. Think about a pancake on a griddle, the pancake slowly spreads out. And the reason it does is the weight of the liquid when you pour it down, and once that spot basically pushes the pancake, so the circle of pancake expands, well, an ice sheet forms when instead of pancake batter, snow falls on the middle of a very cold continent. And as that mountain of snow piles up and transitions to ice, the weight is increasing. And that weight, just under the force of gravity, pulls the whole thing down, and the ice spreads out and eventually covers the continent. That’s what happens in Greenland. And that’s what happens in Antarctica. And then that addition of ice due to snowfall is balanced out, because as the pancake or mountain of snow and ice spreads and gets toward the ocean. Well, the ocean is warmer than the land area in the Arctic. And number two, as that mountain of pancake or ice collapses and spreads, it’s getting lower in altitude. So if you go toward the edges where the ocean is, you’re at sea level eventually, and the atmosphere is colder up high and warmer down near sea level. So those two effects mean that the ice around the edge is going to start to melt a little bit. If you look at the Greenland ice sheet, the primary contribution to sea level rise is the runoff of melting water. Antarctica is a little more complicated. The ice doesn’t just melt there, it doesn’t melt much at all. In fact, what it does is it slides. Just think of that pancake again, the stuff is oozing towards the edge of the pan. Same thing with the ice, it oozes or flows. And when it gets to the water to the ocean edge, pieces break off — those are icebergs. So there are two contributions to sea level rise from these ice sheets, direct melting and their warmer parts, and flow and formation of icebergs when the flowing ice gets to the ocean’s edge.

CURWOOD: Michael, give me some numbers, what’s going on with the nexus of sea level rise and the loss of ice?

OPPENHEIMER: Well, let’s look at it historically, what happened during the 20th century, for instance. Sea level rose about six inches. And that was largely absent any significant contribution except for the last 15 years maybe of that century from the ice sheets. And it rose six inches, largely due to thermal expansion and the melting of mountain glaciers. As I said, the rate is now accelerated, it’s going now at sea level rise the equivalent of 12 inches per century, but it’s not going to just stay at that level, it’s already accelerating. And it’s going to get faster and faster. By the end of this century, depending on which projections you look at, the rate of sea level rise could wind up being about five times what it was, about five times that six inches in the 20th century. And we’re having trouble dealing with the six inches that we had trouble last century. In this century, five times as fast sea level rises can be awfully difficult to deal with. At this point, we’re not ready for it. We’re not primed to deal with it. We haven’t deployed the adaptive measures that we really need to at the scope and rate that we need to. So this is a looming not just a difficulty, but in some cases a disaster.

CURWOOD: So talk to me about the challenges that coastal communities face now amid these rising sea levels.

OPPENHEIMER: Well, there are two major challenges. One is sea level is rising in some sense faster than people’s ability to grasp what’s going on and government’s ability to mobilize and act. And secondly, there’s a larger uncertainty about exactly what’s going to happen because of the uncertainty in the behavior of the ice sheets. But we know that the thermal expansion of seawater is happening, we know that mountain glaciers are happening, that part is not subject to a lot of uncertainty. And furthermore, the other big uncertainty in this problem is how much greenhouse gas we’re going to emit into the atmosphere in the next 20, 30, 40 years and therefore, how warm the planet will get and therefore how much ice melt and thermal expansion will get. And when you put all that together, what you see interestingly is the difference in the sea level rise projections between a lot of emissions and not too much emissions is not very much until you get out to about 2040/2050. So for the next approximately 30 years, you can say with fairly good confidence that we know what the sea level rise is going to be.

CURWOOD: So what is that number? How much sea level rise for parts of the United States by the year 2050?

OPPENHEIMER: Well, we’re talking about one or two feet, which may not sound huge, but on a typical East Coast beach, a foot of sea level rise takes away a hundred feet of beach horizontally going inland, unless you keep feeding the beach. And that’s just sort of symbolic of what’s going to happen. A lot of areas aren’t beachy. There are buildings in places like downtown Boston or downtown Manhattan, that are just a few feet above sea level, and you add high tide to it, and you add a storm to it, and all of a sudden, you got a lot of flooding, just like happened in Hurricane Sandy. or forget Hurricane Sandy, a big Nor’east storm. A Nor’easter in this neighborhood does the same thing at a slightly smaller scale. So we have a problem today, this isn’t a problem for the future. This is what we failed to protect against adequately today.

CURWOOD: If the ice continues to melt at this pace, what does this mean for the future of humanity?

OPPENHEIMER: Well, it means among other things, that we are inevitably going to lose a lot of cultural heritage, because a lot of human cultural heritage is built right along the coast. And that’s unfortunate, but it also means huge amounts of money lost. And it also means lives lost because people are caught unaware in big floods that happen now more and more regularly.

CURWOOD: So before you go, give me an assessment please of what policies you think are necessary to curb this damage to the ice sheets, to at least slow down this process? And what do you think the role of the United States is in this? And for that matter, what do you think of the various climate proposals that are around here in the US?

OPPENHEIMER: The bottom line is we’re not going to get anywhere. And we’re always going to be behind if we don’t implement very quickly a serious program to reduce emissions of the greenhouse gases, particularly carbon dioxide from burning coal, oil and natural gas that are causing the problem in the first place. As much adaptation as you do, climate change will always have run into if you don’t control the greenhouse gas emissions. As much greenhouse gas emissions as you control, it won’t be enough to protect people, unless we also do a significant amount of adaptation. So we have to do both. We need to build cities and other settlements smartly, so they’re not so exposed to sea level rise. There should be funding for building sea walls, surge barriers, whatever coastal defenses are necessary, where they’re necessary, and there should be funding for facilitating people who make the choice to relocate away from the coast or away from forest fire areas or away from any area that’s threatened by climate change, and where there’s a limit to how much protection the governments can offer or that individuals can take upon themselves. So it all fits together that solving climate change isn’t like often some corner by itself. Solving the climate change problem is integral to setting our society right again.

CURWOOD: Michael Oppenheimer is a Professor of Geosciences and International Affairs at Princeton University. Michael, thanks so much for taking the time with us today.

See Also These Links

Nature | “The Worst Is Yet to Come for the Greenland Ice Sheet”

The Guardian | “Melting Antarctic Ice Will Raise Sea Level by 2.5 Meters – Even if Paris Climate Goals Are Met, Study Finds”

Antarctica hit 65 degrees, the highest ever recorded

From an Article by Matthew Cappucci, Washington Post, February 7, 2020

Just days after the Earth saw its warmest January on record, Antarctica has broken its warmest temperature ever recorded. A reading of 65 degrees was taken Thursday at Esperanza Base along Antarctica’s Trinity Peninsula, making it the ordinarily frigid continent’s highest measured temperature in history.

The Argentine research base is on the northern tip of the Antarctic Peninsula. Randy Cerveny, who tracks extremes for the World Meteorological Organization, called Thursday’s reading a “likely record,” although the mark will still have to be officially reviewed and certified.

The balmy reading beats out the previous record of 63.5 degrees, which occurred March 24, 2015.

The Antarctic Peninsula, on which Thursday’s anomaly was recorded, is one of the fastest-warming regions in the world. In just the past 50 years, temperatures have surged a staggering 5 degrees in response to Earth’s swiftly warming climate. Around 87 percent of glaciers along the peninsula’s west coast have retreated in that time, the majority doing so at an accelerated pace since 2008.

The WMO notes that cracks in the Pine Island Glacier “have been growing rapidly” in the past several days, according to satellite imagery.

The recent spate of warmth owes to a ridge of high pressure that has lingered over the region for several days. High-pressure systems feature sinking air, which favors milder temperatures. This effect was amplified on a local level because of a “foehn” wind, characterized by air sweeping down a mountain that begins compressing as air pressures rise near the Earth’s surface. That causes additional warming.

Moreover, a look at simulated atmospheric profiles around the time it hit the record indicated warmer air aloft than at the surface — meaning any air that mixed down to ground level could have had an additional leg up in warming.

It’s been an eventful year for climate extremes, and we’re only on Day 38 of 2020. January was the warmest on record globally, according to atmospheric monitoring group Copernicus, with records shattered in Europe and Asia. A number of locales in Eastern Europe and particularly Russia wound up more than 12 to 13 degrees above average.

“[This record] doesn’t come as any surprise,” wrote Eric Steig, a glaciologist studying climate change at the University of Washington. “Although there is decade-to-decade variability, the underlying trend across most of the continent is warming.”

He says this record will probably be broken again in the not-so-distant future. “That warming has been particularly fast on the Antarctic Peninsula — where Esperanza is — in summer (the season [they’re] now in),” Steig wrote. “So we can expect these sorts of records to be set again and again, even if they aren’t set every single year.”

David Bromwich, a climate researcher at Ohio State University, noted, however, that while the Antarctic Peninsula has warmed strongly since the late 1940s, temperature trends in summer have been variable in recent decades, including a brief cooling spell since 1998. “So overall, this record looks to be a one time extreme event that doesn’t tell us anything about Antarctic climate change,” he wrote in an email.

Additional extreme warmth is likely in the Antarctic Peninsula in the coming days. Temperatures some 40 to 50 degrees above normal are predicted by some models.

>>> Matthew Cappucci is a meteorologist for Capital Weather Gang. He earned a B.A. in atmospheric sciences from Harvard University in 2019, and has contributed to The Washington Post since he was 18.

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See also: Antarctica — Changes in thickness and sea level, 1992 to 2017

This animation illustrates changes in thickness and sea level contribution due to Antarctica between 1992 and 2017.