As climate changes, warming is expected to be especially rapid at high latitudes. In the Arctic, a lengthening melt season over the last few decades has already reduced the volume and extent of sea ice, with year-on-year ice-loss rates generally exceeding predictions.
One reason for the failure of models to predict this loss accurately might lie in how they account for melt ponds. The formation and growth of these ponds, which occurs at the transition between sea ice and open ocean, includes a positive feedback loop that makes the system especially sensitive.
“Pond evolution largely controls sea-ice albedo, a key parameter in climate modelling and one of the most important — and least understood — processes in determining the role of sea ice in the climate system,” says Kenneth Golden of the University of Utah, US.
As melt ponds form on the sea-ice surface, highly-reflective ice and snow are replaced by darker pools of water. The meltwater absorbs more solar radiation and warms up more than the ice that it replaces; the extra energy can trigger additional melting in its surroundings. When the melt pond penetrates the full thickness of the ice, warmer ocean water floods in from below, accelerating the process.
Existing descriptions of pond formation in global climate models consider the overall volume of meltwater but not its surface distribution. Yet, because the albedo change caused by melt ponds is a surface process, and because the rate at which ponds conduct heat to their surroundings depends on their perimeter, understanding the rules governing melt pond sizes is crucial for climate modelling.
The standard Ising model comprises a lattice of interacting particles, each of which is assigned a spin value that is either up or down. To capture the detailed geometry of melt ponds, Golden, with colleagues at Northumbria University, UK, the University of Dayton, US, and the University of Utah, US, created a version where the lattice represents the sea-ice surface, and each node a pixel of either ice or liquid water.
Starting with a random input configuration that does not resemble the real-world, each node interacts with its neighbours until the system settles on a local low-energy state. With a lattice spacing of 1 metre – the length scale over which Arctic ice exhibits significant topographic differences – the pattern that emerges from the energy-minimization process closely matches the melt-pond distribution seen in real life. For example, both real and modelled ponds scale in size according to the same power law, and both form more complex, fractal shapes when they grow larger than 100 sq. m.
Advertisement“The approach could ultimately lead to a framework for representing pattern formation occurring at spatial scales smaller than the grid spacing used in global climate models, which currently track meltwater volume without representing its spatial distribution,” says Golden.
Other parameters that describe ferromagnetic behaviour in the original Ising model also have real-world analogues in the version adapted for sea-ice. The global magnetic field, for example, which conventionally governs how likely particle spins are to align as up or down, now corresponds to solar energy input, making each lattice point more or less likely to be water or ice. The strength of coupling between neighbouring particle spins, meanwhile, now describes heat flow between water and ice in adjacent pixels.
Although Golden and colleagues ran their model with zero global field and an infinite coupling strength, changing these parameters after the initial process could perturb a realistic pond arrangement from its metastable state into an alternative low-energy configuration. In this way, the researchers might simulate how sea ice evolves as melt ponds respond to changing environmental conditions.
Climate change is no longer theoretical. It’s in our backyard.
Here are four snapshots of this new reality — and what we’re doing about it.
The only thing I’m thinking is my mama burning alive, and she’ll be crying out my name.
When John Bino learned that a wildfire was closing in on his home in Fort McMurray’s Abasand neighbourhood on May 3, 2016, he was at work — one and a half hours away.
John Bino holds up the framed number of his house in Fort McMurray.
John Bino holds up the framed number of his house in Fort McMurray, which burned to the ground in the 2016 wildfire. (Craig Chivers/CBC)
He called home and told his wife, Jenny Solidum, to gather their two young boys and go to a friend’s place in nearby Timberlea. In the meantime, Bino would drive back to the house to retrieve his 76-year-old mother, who was visiting from India. She was a polio survivor and too heavy for his wife to lift.
But by the time he arrived at home, police had barricaded the road. Bino pleaded with them to let him through.
“I said, ‘My mom, she’s handicapped, she cannot move. She doesn’t speak the language. She’s stuck. She has no idea what’s happening. We need to rescue her and the door is locked.'”
Police assured him his mother would be rescued and told him to go. Bino waited hours at a nearby evacuation centre. But Solidum kept calling him, in a panic, as the fire approached Timberlea.
“I had to make a decision, right? To take care of my wife and kids or to take care of my mom.” Bino decided to rejoin his family. But as they fled north from evacuation centre to evacuation centre and eventually onto a flight to Calgary, Bino made frantic phone calls to 911 and the Red Cross. No one knew anything about his mother’s whereabouts.
Bino tried not to dwell on reports that Abasand was burning. “The only thing I’m thinking is my mama burning alive, and she’ll be crying out my name.”
Two days after being forced to abandon his home, Bino got a surprise phone call. A doctor at Leduc Community Hospital, just outside Edmonton, asked if he knew someone named Salimma Michael, who had been airlifted to safety.
“I was so relieved, my knees were shaking,” Bino said. The family rushed to Edmonton, and arrived at the hospital to visit Michael the next morning.
When Bino and Solidum bought the house in Abasand back in 2014, they loved the fact that the neighbourhood was on a hill surrounded by forest. “The trails were great. And it was peaceful and quiet,” Bino said. “No one ever mentioned [anything] about forest fires being a risk.”
Infographic showing the number of hectares burned by wildfires each year across Canada. Source: National Forestry Database
There has been a “significant increase” in the area burned by wildfires each year across Canada, Environment Canada reports. On average, wildfires in Canada have been burning 2.5 million hectares a year (nearly half the area of Nova Scotia) — double the 1970s average. B.C. and Alberta have been bearing the brunt of that increase.
Source: National Forestry Database
Climate change has increased the risk of major wildfires by extending the fire season by several weeks and generating hotter, drier conditions that support more extreme, fast-burning fires. The Fort McMurray fire in 2016, nicknamed “The Beast,” led to the largest wildfire evacuation in Canadian history. By the time it was extinguished that August, the fire had destroyed 6,000 square kilometres and caused $3.8 billion in insured damage alone.
When Bino and Solidum finally returned to the house, it was among 2,400 buildings that had burned to the ground. Almost everything the family owned was gone — from their children’s first locks of hair to a medal of valour Bino’s late father had received from the Indian navy.
The events of those few, intense days changed Bino’s perspective. “You know, we got our mom back. So to hell with the stuff, right?” But their struggles weren’t over. Solidum was so traumatized by the event, and the guilt of leaving Bino’s mother behind, that for more than a year, she became shell-shocked and unresponsive whenever she heard sirens or saw flashing lights.
Ashy remains of Bino’s neighbourhood after the wildfire had been extinguished.
This photo of the Abasand neighbourhood after the fire was taken by John Bino’s neighbour, Peter Fortna, when residents were allowed to return and look for belongings that may have survived. (Peter Fortna)
Bino also suffered. He was laid off from his engineering job, and once the family had settled in Edmonton, he got a position that required a five-hour commute back to Fort McMurray. Bino ended up quitting that job to care for his mother, but the situation eventually became untenable, and he was forced to send his mother back to India.
In spite of the trauma, Bino said the whole experience left him with a deep sense of gratitude for his family’s safety and care.
“The government, people — everybody was so helpful. It was amazing. It was like … how do people care about each other so damn much here?”
Adapting to wildfires
Climate change is the biggest and most significant factor behind the increase in wildfire risk and damage, said Laura Stewart, president of Firesmart Canada, which provides tools to communities to reduce the risks and impacts of wildfires.
But the development of industry and housing in forested or grassland areas also plays a role — as illustrated by Fort McMurray’s Abasand neighbourhood, which is surrounded by boreal forest.
Boreal forests contain trees like jack pine and lodgepole pine, whose seed cones only open when exposed to heat, and are reliant on wildfires to regenerate.
Natural Resources Canada estimates the cost of managing wildfires has been rising about $120 million per decade since 1970, to an annual cost of up to $1 billion in recent years.
Governments and communities can reduce the risks and impacts of wildfires by:
Imposing fire bans or even forest closures to shut down industrial operations when the risk of fires is high.
Thinning or removing conifer trees in surrounding communities to reduce the risk of crown fires, which spread from treetop to treetop, and are the most intense and dangerous wildland fires.
Creating fire breaks around communities, such as golf courses and soccer fields.
Burying power lines to eliminate the risk of them starting fires (as happened in California in 2018).
June has set a record low of Arctic sea ice, while the extent of melting across the Greenland Ice Sheet this early in the summer has never been seen before.
Recently, temperatures in parts of Greenland soared to 40 degrees above normal, while open water (not covered by sea ice) is already being observed in places north of Alaska where it has seldom, if ever, been observed.
Rick Thoman, a Fairbanks-based climatologist, told The Washington Postthat the loss of sea ice over the Chukchi and Beaufort seas of Alaska’s northern coast is now “unprecedented.”
Scientists have long been warning that what happens in the Arctic does not stay in the Arctic. Some liken the situation to what happens when a refrigerator door is left open. The cold air that is usually contained within the Arctic region of the planet is now often being displaced by high-pressure zones in the Arctic, all of which is then being augmented by human-caused climate disruption. This has resulted in lower-than-normal temperatures across much of the central and eastern United States in early June, while the Arctic was baking under abnormally high temperatures that have facilitated the unprecedented melting of ice across so much of the region.
“The jet stream this week was one of the craziest I’ve ever seen!” Jennifer Francis, a leading researcher who has published studies connecting mid-latitude weather to the dramatic changes across the Arctic, told The Washington Post.
Greenland Is Melting, Seals Are Dying
By mid-June, nearly half of the ice of the Greenland Ice Sheet was melting. One day alone saw a loss of two billion metric tons of ice. This photo, which is not photo-shopped, is worth viewing. It displays a dogsled being used by scientists to retrieve their oceanographic moorings and a weather station in Northwest Greenland atop an ice sheet that is literally melting underneath their feet.
“Officials say areas experiencing lesser ‘severe’ and ‘moderate’ droughts have also expanded and the region’s precipitation, while higher than other areas, is drastically less than normal,” the CBC reported of the crisis.
On June 13, the Anchorage Daily News reported that the National Oceanic and Atmospheric Administration (NOAA) was investigating “unusually large numbers” of dead ice seals along the Bering and Chukchi sea coasts. The seals are integral to the subsistence lifestyle of the Inuit people in the area.
“Harold Okitkun was maneuvering his skiff along the coastline near the Western Alaska village of Kotlik on Friday afternoon when he first saw the seal carcasses, he said,” reported the Anchorage Daily News. “He counted 18 dead ice seals along about 11 miles of shore. In his 48 years in the village, he’d never seen anything like it, he said. It was overwhelming.”
NOAA received reports of at least 60 dead ice seals along the west coast of Alaska in just the last month. This was enough to cause the agency to launch an investigation into what it said are “unusually large numbers” of seal deaths.
“At this point, we don’t know what’s going on,” Julie Speegle, spokeswoman for NOAA Fisheries Alaska Region, told the Anchorage Daily News. “We are mobilizing crews to go out and collect some samples and try to investigate what’s happening.”
Of course, the brutal impacts of climate disruption on the Arctic aren’t new this year. During an interview in Anchorage in 2016, Bruce Wright, a senior scientist with the Aleutian Pribilof Islands Association (APIA), told Truthout of a warming event that occurred in Alaska in 2015: “This last summer, the gulf warmed up 15°C warmer than normal in some areas,” Wright told me. “Yes, you heard me right. 15°C. And it is now, overall, 5°C above normal in both the Gulf of Alaska and Bering Sea, and has been all winter long.”
Wright discussed how the climate-disruption-driven warming of the Northern Pacific and the Gulf of Alaska was driving toxic algal blooms. This, coupled with the warmer waters, had “broken” the food web in his region.
This, along with all the other catastrophic global impacts of human-caused climate disruption, caused Wright to issue a bleak prognosis for the future.
“We’re not going to stop this train wreck,” Wright told Truthout. “We are not even trying to slow down the production of CO2, and there is already enough CO2 in the atmosphere. We are going to see the consequences, and they will be significant.”
Recent data show steep increases in CO2 for the seventh year running, as atmospheric carbon dioxide levels have increased by their second highest annual rise in the last six decades.
Two images from this event have captured the attention of international media. The first was a graph produced at the National Snow and Ice Data Center with a near vertical line showing the dramatic increase in the area melting.
The second was a photograph showing a dogsled team mushing through ankle deep meltwater on top of sea ice. The juxtaposition of the image and data provide a compelling message about the changing environment in and around the Greenland ice sheet.
The Greenland ice sheet is roughly the size of Alaska and contains enough ice to raise global sea level by more than 20 feet. Greenland gains ice each year through snow accumulation. It loses ice through icebergs breaking off the margin and meltwater that drains through the ice and into the ocean.
The past three summers have seen more modest melt, but a warmer than normal spring and the extensive melt so far this year is likely to lead to massive losses this summer.
The satellite data are collected from a series of NOAA and Department of Defense satellites that record naturally emitted microwave radiation. Wet snow and ice appear bright in these images, compared to dark areas of dry snow.
The early onset to melt has important implications for the remainder of the summer. At the beginning of spring, fresh snow and compacted snow from previous years (called firn) is much colder than the freezing point. The snow and firn must be warmed to freezing before melt can start. Once melt is underway, the snow remains near the freezing point even after refreezing. Not all meltwater goes into the ocean; the firn has pores, like a sponge, that allows some of the meltwater to refreeze and acts as a buffer to sea level rise, but increasing surface melt is filling the pores, which will lead to more meltwater runoff into the ocean.
Meanwhile, snowmelt along the margin of the ice sheet also exposes bare glacial ice and allows surface meltwater ponds to fill. The refrozen snow and firn, bare ice, and meltwater ponds are much darker and absorb more sunlight than fresh snow, promoting even more melt.
Aerial view of icebergs on Arctic Ocean in Greenland. Explora_2005 / iStock / Getty Images
The annual Arctic thaw has kicked off with record-setting ice melt and sea ice loss that is several weeks ahead of schedule, scientists said, as the New York Times reported.
Meanwhile, thousands of miles away, there is open water in areas north of Alaska where it is rarely, if ever, seen, the Washington Post reported.
The accelerated ice melt in Greenland was caused by an usual weather pattern, where high-pressure air lingered, bringing warm air up from the south, which pushed the mercury 40 degrees Fahrenheit above normal temperatures. Add to that continuously cloudless skies and snowfall that is well below normal, and the conditions were ripe for melting across most of the ice sheet.
Last week, Greenland lost 2 billion tons of ice or about 45 percent of the surface in just one day. Measuring about 275,000 square miles, the ice melt was slightly larger than Texas, said Marco Tedesco, a geophysicist at Columbia University’s Lamont-Doherty Earth Observatory, according to the New York Times.
While the high temperatures set a record early date for such widespread melting, there was slightly greater melting in 2012, but a bit later in June. That year, high pressure returned during the summer months, which caused record ice-sheet melt. Greenland lost 200 billion tons of ice that summer, the New York Timesreported. But, so much melting this early in summer could be ominous, putting 2019 on pace to set a new record for ice loss, according to CNN.
“The melting is big and early,” said Jason Box, a climatologist at the Geological Survey of Denmark and Greenland, as the Washington Post reported. In May, Box predicted that 2019 would be a big melt year for Greenland, as CNN reported.
His prediction was based on the lower than average snow cover in Western Greenland and the melt days that began in April, which is unusually early. The melt season also started three weeks earlier than average and earlier than the record-setting year of 2012, according to CNN.
The warming Arctic permafrost may be releasing more nitrous oxide, a potent greenhouse gas, than previously thought
BYCaitlin McDermott-MurphyHarvard Correspondent
About a quarter of the Northern Hemisphere is covered in permafrost. Now, it turns out these permanently frozen beds of soil, rock, and sediment are actually not so permanent: They’re thawing at an increasing rate.
Human-induced climate change is warming these lands, melting the ice and loosening the soil, and that can cause severe damage. Forests are falling; roads are collapsing; and, in an ironic twist, the warmer soil is releasing even more greenhouse gases, which could further exacerbate the effects of climate change.
Shortly after scientists first noticed signs of thaw in the early 1970s, they rushed to monitor emissions of the two most influential greenhouse gases — carbon dioxide and methane. But until recently, the threat of the third-most-prevalent gas, nitrous oxide (N2O) — known in dentistry as laughing gas — has largely been ignored.
In a 2010 paper, the Environmental Protection Agency (EPA) rated permafrost nitrous oxide emissions as “negligible,” and few studies counter this claim.
But a paper published this month in the journal Atmospheric Chemistry and Physics shows that nitrous oxide emissions from thawing Alaskan permafrost are about 12 times higher than previously assumed. Since N2O traps heat nearly 300 times more efficiently than carbon dioxide does, this revelation could mean that the Arctic — and the global climate — are in more danger than we thought. “Much smaller increases in nitrous oxide would entail the same kind of climate change that a large plume of CO2would cause,” said Wilkerson, the paper’s first author and a Ph.D. student at the Graduate School of Arts and Sciences based in the lab of James G. Anderson, the Philip S. Weld Professor of Atmospheric Chemistry at Harvard.
In August 2013, before Wilkerson joined the Anderson lab, members of the lab and scientists from the National Oceanic and Atmospheric Administration (NOAA) traveled to the North Slope region of Alaska, bringing with them a specially outfitted small plane that collected data on four greenhouse gases — carbon dioxide, methane, water vapor, and nitrous oxide — that are naturally released from soil and water as part of microbial processes. Flying low, the airborne laboratory collected the gases over nearly 200 square miles, an area about four times the size of Boston proper. Using the eddy covariance technique, which measures vertical wind speed and the concentration of trace gases in the atmosphere, the team could determine whether more gases rose or fell.
In this case, what goes up does not always come down: Greenhouse gases rise into the atmosphere, where they trap heat and warm the planet. And nitrous oxide poses an even greater threat: In the stratosphere, sunlight and oxygen team up to convert the gas into reactive nitrogen oxides that eat away at the ozone layer, which absorbs most of the sun’s harmful ultraviolet radiation. According to the EPA, atmospheric levels of the gas are rising overall, and the molecules can stay in the atmosphere for up to 114 years.
When Wilkerson joined Anderson’s lab in 2013, the nitrous oxide data were still raw. He asked if he could analyze the numbers. “It wasn’t expected to be interesting or take very long,” Wilkerson said. “I viewed it as a mini-project. I said let’s use this data we have, because frankly collecting it had been very expensive. I thought I might as well do this, and I can get more eddy covariance experience at the same time.”
Sure, Anderson said, go right ahead. Both men figured the data would confirm what everyone already seemed to know: Nitrous oxide from permafrost is not a credible threat.
“The assumption is that these permafrost soils are so cold there wouldn’t be much microbial activity,” Wilkerson said. “Until 2009 there was no indication by any study whatsoever that emissions could actually be quite large in permafrost regions.”
Limited research had been done using core samples, which are warmed in the controlled environment of a laboratory to see how much gas the sampled peat releases, or 15 or 20 enclosed cylinders about 18 inches in diameter and several inches deep that sample a square meter or so of the gases released from the soil in which they’re embedded. Those studies suggested N2O might be higher than previously suspected but, said Wilkerson, “they didn’t gain much traction because they were looking at such small areas. It was easy to dismiss them as not being representative of permafrost as a whole.”
The Anderson data covered far more ground than any previous study, and when Wilkerson ran the calculations he found that high emissions were relatively widespread.
In just one month, the plane had recorded enough nitrous oxide to fulfill the expected cap for an entire year. Though the Anderson data represented just 193 of the 5.5 million square miles of the Arctic — like using a Rhode Island–sized plot to represent the entire United States — “it was 10 million times larger than any previous study looking at permafrost N2O emissions,” said Wilkerson. “It makes [previous] findings quite a bit more serious.”
Wilkerson hopes this new analysis will inspire further research. “We don’t know how much more it’s going to increase,” he said, “and we didn’t know it was significant at all because the other studies were on such a small spatial scale that we didn’t know whether they were representative of the larger region.”
Eddy covariance towers across the Arctic use the same technology the Anderson team used in their plane to monitor carbon dioxide and methane. But “not a single one of those towers in a permafrost region measures N2O,” said Wilkinson. “It can be done, because there was a proof-of-concept tower set up temporarily in 2006 near a dairy farm in the Netherlands.” With chambers, scientists have to physically go and collect gas samples every hour, but if the towers were set up to collect N2O, numbers over a large area would be much more robust
In December NOAA reported that the Arctic is warming almost twice as fast as the rest of the planet, and the permafrost, too, is predicted to thaw at an ever-increasing rate. The warm temperatures could also bring more vegetation to the region, which could help decrease future nitrous-oxide levels, since plants absorb nitrogen. But to understand how plants might mitigate the risk, researchers need more data on the risk itself.
Wilkerson hopes researchers hurry up and collect this data, whether by plane, tower, chamber, or core. Or better yet, all four. “This needs to be taken more seriously than it is right now,” he said. Because as the planet warms, permafrost could continue to melt — which would contribute to warming the planet, which would melt more frost. To figure out how to slow this cycle, we first need to know just how bad the situation is.
Russia launched a nuclear-powered icebreaker on Saturday, part of an ambitious programme to renew and expand its fleet of the vessels in order to improve its ability to tap the Arctic’s commercial potential.
The ship, dubbed the Ural and which was floated out from a dockyard in St Petersburg, is one of a trio that when completed will be the largest and most powerful icebreakers in the world.
Russia is building new infrastructure and overhauling its ports as, amid warmer climate cycles, it readies for more traffic via what it calls the Northern Sea Route (NSR) which it envisages being navigable year-round.
The Ural is due to be handed over to Russia’s state-owned nuclear energy corporation Rosatom in 2022 after the two other icebreakers in the same series, Arktika (Arctic) and Sibir (Siberia), enter service.
“The Ural together with its sisters are central to our strategic project of opening the NSR to all-year activity,” Alexey Likhachev, Rosatom’s chief executive, was quoted saying.
President Vladimir Putin said in April Russia was stepping up construction of icebreakers with the aim of significantly boosting freight traffic along its Arctic coast.
The drive is part of a push to strengthen Moscow’s hand in the High North as it vies for dominance with traditional rivals Canada, the US and Norway, as well as newcomer China.
By 2035, Putin said Russia’s Arctic fleet would operate at least 13 heavy-duty icebreakers, nine of which would be powered by nuclear reactors.
The Arctic holds oil and gas reserves equivalent to 412 billion barrels of oil, about 22% of the world’s undiscovered oil and gas, the US Geological Survey estimates.
Moscow hopes the route which runs from Murmansk to the Bering Strait near Alaska could take off as it cuts sea transport times from Asia to Europe.
Designed to be crewed by 75 people, the Ural will be able to slice through ice up to three metres thick.
Greenland’s ice sheet is melting six times faster than it was in the 1980s — that’s even faster than scientists thought.
A new study has revealed that melting Greenland ice has contributed to more than half an inch of global sea-level rise since 1972. Half of that increase happened in the last eight years.
If all of Greenland’s ice were to melt, it would raise sea levels 23 feet, submerging some coastal cities. In the US, that would put everything south of West Palm Beach, Florida underwater.
Greenland’s ice is melting six times faster now than it was four decades ago.
The authors of a new study published in the journal Proceedings of the National Academy of Sciences estimate that the Greenland ice sheet is now sloughing off an average of 286 billion tons of ice per year. In 2012, Greenland lost more than 400 billion tons of ice.
Two decades ago, the annual average was just 50 billion.
All that lost ice means Greenland’s melting has contributed to more than 0.5 inches of global sea-level rise since 1972, the researchers reported. Alarmingly, half of that increase came about in the last eight years alone.
Another study published in January 2019 used data from satellites and a GPS network to determine that Greenland’s ice is melting faster than scientists previously thought. That study highlighted risks of melting in Greenland’s southwestern region, which isn’t typically known to be a source of ice loss, as Quartz reported.
“This is going to cause additional sea-level rise,” Michael Bevis, lead author of the January study and a professor at Ohio State University, told National Geographic. “We are watching the ice sheet hit a tipping point.”
This news comes in the wake of another ominous finding: Antarctica’s melting is also speeding up. In the 1980s, Antarctica lost 40 billion tons of ice annually. In the last decade, that number jumped to an average of 252 billion tons per year — just a hair behind Greenland’s new average.
What happens if the entire Greenland ice sheet melts?
Roughly 1.7 million square kilometers (656,000 square miles) in size, the Greenland ice sheet covers an area almost three times that of Texas. Together with Antarctica’s ice sheet, it contains more than 99% of the world’s fresh water, according to the National Snow and Ice Data Center.
Most of that water is frozen in masses of ice and snow that can be up to 10,000 feet thick. But as human activity sends more greenhouse gases into the atmosphere, the oceans absorb 93% of the excess heat those gases trap. The warm air and water is leading ice sheets to melt at unprecedented rates.
If the entire Greenland ice sheet were to melt — granted, this would take place over centuries — it would mean a 23-foot rise in sea level, on average. That’s enough to submerge the southern tip of Florida.
If both Antarctica and Greenland’s ice sheets were to melt, that would lead sea levels to rise more than 200 feet (and Florida would disappear).
NASA has created an interactive tool that helps track sea-level rise projections based on how much the two ice sheets are melting. One thing the tool makes very clear: Coastal cities will be heavily impacted.
In the event of a full ice melt, according to a map from National Geographic, cities like Amsterdam, Netherlands; Stockholm, Sweden; Buenos Aires, Argentina; Dakar, Senegal; and Cancun, Mexico (to name just a few) would vanish.
This much is clear: the Arctic is warming fast, and frozen soils are starting to thaw, often for the first time in thousands of years. But how this happens is as murky as the mud that oozes from permafrost when ice melts.
As the temperature of the ground rises above freezing, microorganisms break down organic matter in the soil. Greenhouse gases — including carbon dioxide, methane and nitrous oxide — are released into the atmosphere, accelerating global warming. Soils in the permafrost region hold twice as much carbon as the atmosphere does — almost 1,600 billion tonnes1.
What fraction of that will decompose? Will it be released suddenly, or seep out slowly? We need to find out.
Current models of greenhouse-gas release and climate assume that permafrost thaws gradually from the surface downwards. Deeper layers of organic matter are exposed over decades or even centuries, and some models are beginning to track these slow changes.
But models are ignoring an even more troubling problem. Frozen soil doesn’t just lock up carbon — it physically holds the landscape together. Across the Arctic and Boreal regions, permafrost is collapsing suddenly as pockets of ice within it melt. Instead of a few centimetres of soil thawing each year, several metres of soil can become destabilized within days or weeks. The land can sink and be inundated by swelling lakes and wetlands.
Abrupt thawing of permafrost is dramatic to watch. Returning to field sites in Alaska, for example, we often find that lands that were forested a year ago are now covered with lakes2. Rivers that once ran clear are thick with sediment. Hillsides can liquefy, sometimes taking sensitive scientific equipment with them.
This type of thawing is a serious problem for communities living around the Arctic (see ‘Arctic permafrost’). Roads buckle, houses become unstable. Access to traditional foods is changing, because it is becoming dangerous to travel across the land to hunt. Families cannot reach lines of game traps that have supported them for generations.
In short, permafrost is thawing much more quickly than models have predicted, with unknown consequences for greenhouse-gas release. Researchers urgently need to learn more about it. Here we outline how.
Twice the problem
Permafrost is perennially frozen ground. It is composed of soil, rock or sediment, often with large chunks of ice mixed in. About one-quarter of the land in the Northern Hemisphere is frozen in this way. Carbon has built up in these frozen soils over millennia because organic material from dead plants, animals and microbes has not broken down.
Modellers attempt to project how much of this carbon will be released when the permafrost thaws. It is complicated: for example, they need to understand how much of the carbon in the air will be taken up by plants and returned to the soil, replenishing some of what was lost. Predictions suggest that slow and steady thawing will release around 200 billion tonnes of carbon over the next 300 years under a business-as-usual warming scenario3. That’s equivalent to about 15% of all the soil carbon currently stockpiled in the frozen north.
But that could be a vast underestimate. Around 20% of frozen lands have features that increase the likelihood of abrupt thawing, such as large quantities of ice in the ground or unstable slopes2. Here permafrost thaws quickly and erratically, triggering landslides and rapid erosion. Forests can be flooded, killing large areas of trees. Lakes that have existed for generations can disappear, or their waters can be diverted.
Worse, the most unstable regions also tend to be the most carbon-rich2. For example, 1 million square kilometres of Siberia, Canada and Alaska contain pockets of Yedoma — thick deposits of permafrost from the last ice age4. These deposits are often 90% ice, making them extremely vulnerable to warming. Moreover, because of the glacial dust and grasslands that were folded in when the deposits formed, Yedoma contains 130 billion tonnes of organic carbon — the equivalent of more than a decade of global human greenhouse-gas emissions.
How much permafrost carbon might be released with abrupt thawing? As a first step, this year we synthesized results from published studies of abrupt thawing across the permafrost zone. We asked how this type of thawing influences plants, soils and moisture in the ground. The studies revealed patterns of collapse and recovery. This international project was supported by the Permafrost Carbon Network (www.permafrostcarbon.org), part of the multimillion-dollar global Study of Environmental Arctic Change (SEARCH).
Lakes and wetlands are a big part of the problem because they release large amounts of methane, a greenhouse gas that is much more potent than CO25. Erosion from hills and mountains is also problematic: when hillsides thaw and break up, much CO2 is released as material is destabilized, decomposed or washed into streams or rivers6.
We estimate that abrupt permafrost thawing in lowland lakes and wetlands, together with that in upland hills, could release between 60 billion and 100 billion tonnes of carbon by 2300. This is in addition to the 200 billion tonnes of carbon expected to be released in other regions that will thaw gradually. Although abrupt permafrost thawing will occur in less than 20% of frozen land, it increases permafrost carbon release projections by about 50%. Gradual thawing affects the surface of frozen ground and slowly penetrates downwards. Sudden collapse releases more carbon per square metre because it disrupts stockpiles deep in frozen layers.
Furthermore, because abrupt thawing releases more methane than gradual thawing does, the climate impacts of the two processes will be similar7. So, together, the impacts of thawing permafrost on Earth’s climate could be twice that expected from current models.
Stabilizing the climate at 1.5 °C of warming8 requires massive cuts in carbon emissions from human activities; extra carbon emissions from a thawing Arctic make that even more urgent.
Our estimates are rough and need refining. However, they show that understanding abrupt thawing must be a research priority.
First, climate and soil scientists need to find out where the greatest emissions of methane and CO2 will come from. Although we have a good idea of current numbers of thaw lakes and wetlands9, and how many existed in the past10, we need to be able to project where new ones will appear. We also need to know how quickly they will drain as the climate warms.
Second, the erosion of thawed soils on hillsides is poorly understood. Because collapsing slopes are hard to detect using satellites, only a few large-scale studies have been done, often using data from oil exploration or road surveys. Researchers need to establish how much permafrost carbon is displaced and what happens after it has thawed. For example, it is not known how much will stay in the ground or be buried, and how much will enter the atmosphere as a greenhouse gas11,12. And what happens to this material if it flows into rivers, lakes and estuaries?
Third, we need to identify the extent to which plant growth will offset the carbon that is released by permafrost3. Over time, lakes are invaded by wetland plants, and eventually drain and convert back to tundra. Eroded areas are colonized by plants, which helps to stabilize soils and speed their recovery. Researchers need to monitor how thawed ecosystems evolve, the rate at which vegetation stabilizes, and how these plants accumulate biomass. Vegetation also responds to rising CO2and nutrients, longer growing seasons and changing levels of soil moisture. Modellers will need to predict changing feedbacks between ecological communities and geomorphology as permafrost landscapes transform.
Fourth, the distribution of ice in the ground is the main factor influencing the fate of permafrost carbon. Yet observations of ground ice are sparse. More-widespread geophysical measurements could map pockets of ice below the surface, revealing where it concentrates and how quickly it melts. Machine-learning techniques might even be developed to predict where most ice is buried, by analysing soils and topography at the surface.
To plug these knowledge gaps, we have five recommendations.
Extend measurement technology. There should be better tracking of permafrost and carbon across the Arctic, especially in regions undergoing abrupt thawing. It is important to establish baselines of permafrost and ecosystem change against which future measures can be compared. This will require aircraft-based lidar (light detection and ranging, a surveying technique that uses pulsed laser light), drone-based surveys and better algorithms for image analysis.
Fund monitoring sites. River chemistry can be a sensitive indicator of abrupt thawing, but many monitoring stations are being abandoned13. Instead, there should be increased national and international investment in long-term sites that link land-based observations with aquatic and marine measurements. Better recordings of organic matter and nutrients in rivers would shed light on how permafrost plant and microbial communities respond to abrupt and gradual thawing.
Gather more data. Regions that are vulnerable to abrupt thawing need more boreholes, long-term observatories and experiments. Field measurements should quantify how much CO2 and methane is released to the atmosphere as frozen soils are disturbed and recover. Importantly, permafrost researchers and industry groups must deposit all ground-ice data — even if the information is qualitative — in public archives.
Build holistic models. Earth-system models should include the key processes affecting carbon release from permafrost — including how temperature and moisture influence carbon release for a range of climate and vegetation scenarios. Because abrupt thawing occurs at fine spatial scales, detailed process models of these dynamics could be impractical to run directly within Earth-system models. Frameworks must be developed to understand and quantify the effect of these fine-scale processes at the global level.
Improve reports. Policymakers need the best current estimates of the implications of abrupt thawing on climate change. It needs to be considered within the set of unresolved climate feedbacks, as the Intergovernmental Panel on Climate Change (IPCC) did for gradual thawing in its 2018 special report8. The Permafrost Carbon Network is contributing to such efforts, for example by ensuring that abrupt thawing is characterized in the IPCC’s Special Report on the Ocean and Cryosphere in a Changing Climate, which will be released later this year.
We can’t prevent abrupt thawing of permafrost. But we can try to forecast where and when it is likely to happen, to enable decision makers and communities to protect people and resources. Reducing global emissions might be the surest way to slow further release of permafrost carbon into the atmosphere3. Let’s keep that carbon where it belongs — safely frozen in the stunning soils of the north.
Satellites are used to measure ice loss in Greenland
Satellites are used to measure ice loss in Greenland (AFP Photo/JEFF SCHMALTZ)
Washington (AFP) – Measuring melting ice is a fairly precise business in 2019 — thanks to satellites, weather stations and sophisticated climate models.
By the 1990s and 2000s, scientists were able to make pretty good estimates, although work from previous decades was unreliable due to less advanced technology.
Now, researchers have recalculated the amount of ice lost in Greenland since 1972, the year the first Landsat satellites entered orbit to regularly photograph the Danish territory.
“When you look at several decades, it is best to sit back in your chair before looking at the results, because it is a bit scary to see how fast it is changing,” said French glaciologist Eric Rignot, of the University of California at Irvine.
Rignot co-authored the study, published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS),with colleagues in California, Grenoble, Utrecht and Copenhagen.
“It’s also something that affects the four corners of Greenland, not just the warmer parts in the south,” he said.
– Ice melting six times faster –
Glaciologists use three methods to measure ice melting.
Firstly, satellites measure altitude with a laser: if a glacier melts, the satellite picks up its reduced height.
A second technique involves measuring variations in gravity, as ice loss can be detected through a decrease in gravitational pull. This method has been available since 2002 using NASA satellites.
Thirdly, scientists have developed so-called mass balance models, which compare mass accumulated (rain and snow) with mass lost (ice river discharges) to calculate what is left.
These models, confirmed with field measurements, have become very reliable since the 2000s, according to Rignot — boasting a five to seven percent margin of error, compared to 100 percent a few decades ago.
The research team used these models to “go back in time” and reconstruct Greenland’s ice levels in the 1970s and 1980s.
The limited data available for this period — medium-quality satellite photos, aerial photos, ice cores and other observations — helped refine them.
“We added a little bit of history that did not exist,” said Rignot.
The results: during the 1970s, Greenland accumulated 47 gigatonnes of ice per year, on average. Then, it lost an equivalent volume in the 1980s.
The melting continued at that rate in the 1990s, before a sharp acceleration in the 2000s (187 Gt/year) and even more since 2010 (286 Gt/year).
Ice is melting six times faster than in the 1980s, researchers estimate — and Greenland’s glaciers alone have contributed to a 13.7 millimeter rise in sea levels since 1972, they believe.
“This is an excellent piece of work by a well-established research group using novel methods to extract more information from the available data”, said Colin Summerhayes, of the Scott Polar Research Institute in Cambridge.
As with a similar study carried out by the same team on Antarctica, the new study affords a longer term view of the rapid ice melt being observed in Greenland in recent years.
“This new data better enables us to put recent, dramatic, changes to Greenland’s contribution to global sea level rise into a longer-term context — the ice loss we’ve seen in the last eight years is as much as was lost in the preceding four decades,” said Amber Leeson, a lecturer in Environmental Data Science at Lancaster University.