AuthorTopic: Official Arctic Meltdown Thread  (Read 22562 times)

Offline Surly1

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Scientists Raise Alarm Over Warm Ocean Water Beneath 'Doomsday Glacier'
« Reply #165 on: February 01, 2020, 04:03:44 AM »
'Really, Really Bad': Scientists Raise Alarm Over Warm Ocean Water Beneath 'Doomsday Glacier' in Antarctica
"Warm waters in this part of the world, as remote as they may seem, should serve as a warning to all of us about the potential dire changes to the planet brought about by climate change."

The melt rate of West Antarctica's Thwaites Glacier is an important concern for climate scientists, because this glacier alone is currently responsible for about 1% of global sea level rise. (Photo: Stuart Rankin/Flickr/cc)

A study by British and American scientists revealed that a massive sheet of ice known as the "doomsday glacier" is melting faster than experts previously believed—edging the world closer to a possible sea level rise of more than 10 feet.

Researchers at New York University and the British Antarctic Survey drilled through nearly 2,000 feet of ice in the Thwaites glacier in West Antarctica, to measure temperatures at the 75-mile wide ice sheet's "grounding line," where the ice meets the ocean.

The water just beneath the ice was found to be 32º Fahrenheit—more than 2º above freezing temperature in the Antarctic region.

The findings have "huge implications for global sea level rise," NYU scientist David Holland said in a statement. co-founder and author Bill McKibben was among the climate action campaigners who expressed alarm over the new study.

"Oh, damn," McKibben wrote on social media.

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Offline Surly1

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Permafrost Is Thawing So Fast, Itís Gouging Holes in the Arctic
« Reply #166 on: February 04, 2020, 06:03:42 AM »
Permafrost Is Thawing So Fast, Itís Gouging Holes in the Arctic
Normally, these terrains of frozen soil thaw gradually. But in some places, itís thawing so abruptly that landscapes are collapsing in on themselves.

Abrupt permafrost thaw creates divots in landscapes, releasing high amounts of greenhouse gases.PHOTOGRAPH: DAVID OLEFELDT

It’s perhaps the best known and more worrisome of climate feedback loops: As the planet warms, permafrost—landscapes of frozen soil and rock—begins to thaw. And when it does, microbes consume organic matter, releasing CO2 and methane into the atmosphere, leading to more warming, more thawing, and even more carbon emissions.

But here’s something you’ve probably never heard of, and it’s something not even the UN’s Intergovernmental Panel on Climate Change has really considered: thermokarst. That’s the land that gets ravaged whenever permafrost thaws rapidly. As the ice that holds the soil together disappears, hillsides collapse and massive sinkholes open up. Climate scientists have been working gradual permafrost thaw into their models—changes that run centimeters deep over decades or centuries. But abrupt permafrost thaw happens on the scale of meters over months or years. That shocks the surrounding landscape into releasing potentially even more carbon than would have if it thawed at a more leisurely pace.

Today in the journal Nature Geoscience, researchers argue that without taking abrupt thaws into account, we’re underestimating the impact of permafrost thaw by 50 percent. “The amount of carbon coming off that very narrow amount of abrupt thaw in the landscape, that small area, is still large enough to double the climate consequences and the permafrost carbon feedback,” says study lead author Merritt Turetsky, of the University of Guelph and University of Colorado Boulder.

Less than 20 percent of northern permafrost land is susceptible to this kind of rapid thaw. Some permafrost is simply frozen rock, or even sand. But the kind we’re worried about here contains a whole lot of water. “Where permafrost tends to be lake sediment or organic soils, the type of earth material that can hold a lot of water, these are like sponges on the landscape,” says Turetsky. “When you have thaw, we see really dynamic and rapid changes.”

That’s because frozen water takes up more space than liquid water. When permafrost thaws, it loses a good amount of its volume. Think of it like thawing ice cubes made of water and muck: If you defrost the tray, the greenery will sink to the bottom and settle. “That's exactly what happens in these ecosystems when the permafrost has a lot of ice in it and it thaws,” says Turetsky. “Whatever was at the surface just slumps right down to the bottom. So you get these pits on the land, sometimes meters deep. They're like sinkholes developing in the land.”

“Essentially, we're taking terra firma and making it terra soupy,” Turetsky adds.

As the earth turns to soup, the landscape begins to scar. The process is so rapid and so violent, Turetsky says, that sometimes when she returns to a site she’s monitoring to check her temperature and methane sensors, she’ll find they are gone. “When you come back in, it's a lake and there's three meters of water at the surface. You have to probably say goodbye to your equipment,” she says.

When these lands thaw, they play host to a number of processes. As ice turns to liquid water, trees flood and die off. Thus more light reaches the soil, further accelerating thawing. This is in contrast to gradual thaw, when the plant community largely stays the same as the ice thaws. Defrosted soil at the surface gets thicker and thicker, but it doesn’t catastrophically collapse.

concaved land
Photograph: David Olefeldt

In addition, when you think of permafrost regions, you might think of featureless tundras, but most is actually boreal forest. These northern forests have recently seen an unprecedented number of wildfires. “Much of the boreal forest burns more and more often, and when the ecosystem burns, it can actually accelerate the permafrost thaw,” says David Olefeldt of University of Alberta, coauthor on the paper. Without cover from these trees to shade it, the soil warms ever more intensely.

Abrupt warming also exacerbates emissions from permafrost. In a gradual thaw, the warming top layers of the soil open up to hungry microbes, which consume nutrients and give off CO2. “In the summer, permafrost—the top layer at least—thaws, and then cracks can build,” says Northern Arizona University biogeochemist and plant ecophysiologist Christina Schaedel, who collaborates with the authors of this new paper, but wasn’t involved in the work. In the fall it freezes back up, creating a cycle in which soil layers get mixed down to the bedrock, concentrating carbon at the bottom. “With abrupt thaw, you're exposing deeper layers to much warmer temperatures, and deep layers in permafrost can contain very high amounts of carbon,” Schaedel says.

This can become particularly problematic from an emissions standpoint if the collapsed land forms a pond of water with low oxygen content, and with a layer of rich carbon at the bottom. The microbes that thrive in this kind of environment produce methane as a byproduct, a far more potent greenhouse gas than CO2.

Here’s an important consideration: When permafrost melts abruptly, it doesn’t just release carbon and then retire. That ecosystem can heal and begin sequestering carbon again. If the land has thawed, then collapsed and become inundated with water, new trees can’t grow. Instead, that ecosystem is likely to become dominated by mosses and grass-like sedges. Because the plant material is waterlogged, decomposition actually slows as it forms peat—thick, mucky, layers of organic matter.

aerial of mountains

If on a slope, abrupt thaw can spill massive amount of earth.

Photograph: Carolyn Gibson

“So this rapid post-thaw peat accumulation that happens is eventually how it recovers some of the carbon that was lost,” says USGS research geologist Miriam Jones, coauthor on the new paper. “But I will say that in the permafrost, carbon has accumulated over millennia. And so upon thaw, it’s rapidly lost within years to decades.”

It will take centuries or millennia, depending on the ecosystem, to sequester all that carbon again. And of course in the Arctic, which is warming twice as fast as the rest of the planet, the composition of vegetal species that make up some of its ecosystems are transforming, in turn changing how they sequester carbon.

The more closely scientists can parse what happens when permafrost thaws rapidly, the better they account for how these landscapes emit greenhouse gases—and eventually sequester some, too. The bad news is, the emissions could be the equivalent of an entire industrialized nation’s greenhouse output. The better news is, it won’t be as much as humanity’s global toll. “Even though these are hot spots of carbon release, it's going to take decades for those hot spots to become large enough to seriously impact the climate system,” says Turetsky. “But this is still something we need to take seriously.”

And it’s something that needs far more research. Any climate modeling comes with inherent uncertainties—there’s no way to perfectly represent such complex systems. The uncertainty here is projecting how much land might succumb to abrupt thawing, says University of Alaska Fairbanks permafrost geophysicist Vladimir Romanovsky, who wasn’t involved in the work. Scientists have only begun to study these rapid thaw events, which often happen at extremely small scales.

“It's very difficult in this particular case to use the past to predict the future,” says Romanovsky. “That's understandable, and definitely there are some ways to try to narrow down this uncertainty. But that uncertainty will be there for forever, because of the limitation of all the models to predict this process in the future, in particular the entire area of permafrost existence.”

What’s clear, though, is that ecosystems in the Arctic are literally in upheaval. And the faster we cut emissions, the less they will suffer.

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Offline Eddie

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Re: Official Arctic Meltdown Thread
« Reply #167 on: February 04, 2020, 11:29:06 AM »
Guy McPherson's famous methane gun.

All I can say is that warming does not appear to be going exponential the way he claimed. Not so far. It is trending up, for sure.

Climate models are bound to get better as we go forward. While I recognize climate change is a real problem, I think we can take some hope...because the doomsday scenarios are looking increasingly less likely.

One thing I do believe..and that is that a lot of the articles in the lay press are questionable as far as drawing any useful conclusions.
« Last Edit: February 04, 2020, 03:11:11 PM by Eddie »
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Offline Eddie

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Re: Official Arctic Meltdown Thread
« Reply #168 on: February 04, 2020, 01:37:38 PM »
Judith Curry gets dinged as a climate change denier by some of the more rabid climate change activists out there. But...her credentials are impeccable and I believe that she would be better considered as a very well informed expert who just.happens to hold a modestly contrarian view.  Hardly any kind of climate denier.

And she backs it up with cogent writing, and good science.

I've looked high and low, and I think her take is pretty accurate. Below is a very timely critique of the IPCC FAR report. Simply stated, they got some things seriously wrong. It doesn't mean warming is a hoax. It means the models need to be re-evaluated.

This is a summary. I'll link to the full piece, which was published on her blog a few days ago.

The IPCCís First Assessment report greatly overestimated future rates of atmospheric warming and sea level rise in its Business-as-usual scenario. This projection also overestimated rates of radiative forcing from greenhouse gases. A major part of the mis-estimation of greenhouse forcing happened because the world clamped down on CFCs and HCFCs much more quickly than its projections assumed. This was not a mistake of climate science, but simply a failure to foresee changes in human behaviour.

However, the IPCC also made other errors or omissions, which went the other way: they tended to reduce forecasted forcing and warming. Its Business-as-usual scenario featured CO2 emissions probably lower than those that have actually taken place, and its forcing estimates didnít include tropospheric ozone.

This means that the bulk of the error in FARís forecast stems from two sources:

The fraction of CO2 emissions that remained in the atmosphere was much higher than has been observed, either at the time of the reportís publication or since then. There are uncertainties around the real-world airborne fraction, but the IPCCís figure of 61% is about one third-higher than emission estimates suggest. As a result, CO2 concentrations grew 25% more in FARís Business-as-usual projection than in the real world.

The methane forecast was hopeless: methane concentrations in FARís Business-as-usual scenario grew five or six times more than has been observed. Itís still not clear where exactly the science went wrong, but a deviation of this size cannot be blamed on some massive-yet-imperceptible change in human behaviour.
These are purely problems of inadequate scientific knowledge, or a failure to apply scientific knowledge in climate projections. Perhaps by learning about the mistakes of the past we can create a better future.
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Offline Surly1

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Rapid Permafrost Collapse Is Underway, Disintegrating Landscapes And Predictions
« Reply #169 on: February 06, 2020, 05:02:53 AM »
Don't worry, be happy.

Rapid Permafrost Collapse Is Underway, Disintegrating Landscapes And Our Predictions

Permafrost in Canada, Alaska and Siberia is abruptly crumbling in ways that could release large stores of greenhouse gases more quickly than anticipated, researchers have warned.

Scientists have long fretted that climate change - which has heated Arctic and subarctic regions at double the global rate - will release planet-warming CO2 and methane that has remained safely locked inside Earth's frozen landscapes for millennia.

It was assumed this process would be gradual, leaving humanity time to draw down carbon emissions enough to prevent permafrost thaw from tipping into a self-perpetuating vicious circle of ice melt and global warming.

But a study published on Monday in Nature Geoscience says projections of how much carbon would be released by this kind of slow-and-steady thawing overlook a less well-known process whereby certain types of icy terrain disintegrate suddenly - sometimes within days.

"Although abrupt permafrost thawing will occur in less than 20 percent of frozen land, it increases permafrost carbon release projections by about 50 percent," said lead author Merritt Turetsky, head of the Institute of Arctic and Alpine Research in Boulder, Colorado.

"Under all future warming scenarios, abrupt thaw leads to net carbon losses into the atmosphere," she told AFP.

Permafrost contains rocks, soil, sand and pockets of pure ground ice. Its rich carbon content is the remains of life that once flourished in the Arctic, including plants, animals and microbes.

This matter - which never fully decomposed - has been frozen for thousands of years.

It stretches across an area nearly as big as Canada and the United States combined, and holds about 1,500 billion tonnes or carbon - twice as much as in the atmosphere and three times the amount humanity has emitted since the start of industrialisation.

Some of this once rock-solid ground has begun to soften, upending indigenous communities and threatening industrial infrastructure across the sub-Arctic region, especially in Russia.

The evidence is mixed as to whether this not-so-permanent permafrost has started to vent significant quantities of methane or CO2.

Projections are also uncertain, with some scientists saying future emissions may be at least partially offset by new vegetation, which absorbs and stores CO2.

But there is no doubt, experts say, that permafrost will continue to give way as temperatures climb.

'Fast and dramatic'

In a special report published in September, the UN's scientific advisory body for climate change, the IPCC, looked at two scenarios.

If humanity manages - against all odds - to cap global warming at under 2įC, the cornerstone goal of the 2015 Paris climate treaty, "permafrost area shows a decrease of 24 percent by 2100", it concluded.

At the other extreme, if fossil fuel emissions continue to grow over the next 50 years - arguably an equally unlikely prospect - up to 70 percent of permafrost could disappear, the IPPC said.

But both scenarios assume the loss will be gradual, and that may be a mistake, Turetsky suggested.

"We estimate that abrupt permafrost thawing - in lowland lakes and wetlands, together with that in upland hills - could release 60 to 100 billion tonnes of carbon by 2300," she and colleagues noted in a 2019 comment also published by Nature.

One tonne of carbon is equivalent to 3.67 tonnes of carbon dioxide (CO2), which means this would be equivalent to about eight years of global emissions at current rates.

"This is in addition to the 200 billion tonnes of carbon expected to be released in other regions that will thaw gradually," she said.

Current climate models do not account for the possibility of rapid permafrost collapse and the amount of gases it might release, the study notes.

Abrupt thawing is "fast and dramatic", Merritt said, adding: "Forests can become lakes in the course of a month, landslides can occur with no warning, and invisible methane seep holes can swallow snowmobiles whole."

© Agence France-Presse
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Offline Surly1

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Arctic sinkholes open in a flash after permafrost melt
« Reply #170 on: February 06, 2020, 05:23:06 AM »
Arctic sinkholes open in a flash after permafrost melt
By Mindy Weisberger 05 February 2020

Some permafrost zones thaw faster than expected and are reshaping the Arctic landscape.

Trees struggle to remain upright in a lake formed by abrupt permafrost thaw.(Image credit: David Olefeldt)

Arctic permafrost can thaw so quickly that it triggers landslides, drowns forests and opens gaping sinkholes. This rapid melt, described in a new study, can dramatically reshape the Arctic landscape in just a few months. 

Fast-melting permafrost is also more widespread than once thought. About 20% of the Arctic's permafrost — a blend of frozen sand, soil and rocks — also has a high volume of ground ice, making it vulnerable to rapid thawing. When the ice that binds the rocky material melts away, it leaves behind a marshy, eroded land surface known as thermokarst. 

Previous climate models overlooked this kind of surface in estimating Arctic permafrost loss, researchers reported. That oversight likely skewed predictions of how much sequestered carbon could be released by melting permafrost, and new estimates suggest that permafrost could pump twice as much carbon into the atmosphere as scientists formerly estimated, the study found.

Related: Photos: Perfectly preserved baby horse unearthed in permafrost

Frozen water takes up more space than liquid water, so when ice-rich permafrost thaws rapidly — "due to climate change or wildfire or other disturbance" — it transforms a formerly frozen Arctic ecosystem into a flooded, "soupy mess," prone to floods and soil collapse, said lead study author Merritt Turetsky, director of the Institute of Arctic and Alpine Research (INSTAAR) at the University of Colorado Boulder. 

"This can happen very quickly, causing relatively dry and solid ecosystems (such as forests) to turn into lakes in the matter of months to years," and the effects can extend into the soil to a depth of several meters, Turetsky told Live Science in an email. 

By comparison, "gradual thaw slowly affects soil by centimeters over decades," Turetsky said.

Creating feedback

Across the Arctic, long-frozen permafrost is melting as climate change drives global temperatures higher. Permafrost represents about 15% of Earth's soil, but it holds about 60% of the planet's soil-stored carbon: approximately 1.5 trillion tons (1.4 trillion metric tons) of carbon, according to the National Snow and Ice Data Center.

When permafrost thaws, it releases stored carbon into the atmosphere. This release can then speed up global warming; this cycle is known as climate feedback, the scientists wrote in the study.

Aerial image of a permafrost peatland in Alaska's Innoko National Wildlife Refuge, interspersed with smaller areas of thermokarst wetlands. (Image credit: Miriam Jones, U.S. Geological Survey)

In fact, carbon emissions from about 965,000 square miles (2.5 million square kilometers) of quick-thawed thermokarst could provide climate feedback similar to emissions produced by nearly 7 million square miles (18 million square km) of permafrost that thawed gradually, the researchers reported.

And yet, rapid thawing from permafrost is "not represented in any existing global model," study co-author David Lawrence, a senior scientist with the National Center for Atmospheric Research, said in a statement.

Abrupt permafrost thaw was likely excluded from prior emissions models because it represents such a small percentage of the Arctic's land surface, Turetsky explained.

"Our study proves that models need to account for both types of permafrost thaw — both slow and steady change as well as abrupt thermokarst — if the goal is to quantify climate feedbacks in the Arctic," Turetsky added.

The findings were published online Feb. 3 in the journal Nature Geoscience.

Originally published on Live Science.

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