Climate

In pictures from high above, the island of Gardi Sugdub resembles a container shipyard — small, brightly colored dwellings are jammed together cheek to jowl. At ground level, the island, one of more than 350 in the San Blas archipelago off the northern coast of Panama, is hot, flat and crowded. More than 1,000 people occupy the narrow dwellings that cover virtually every bit of the 150-by-400-meter island, which is slowly being swallowed by rising seas driven by climate change.

This year, about 300 families from Gardi Sugdub are expected to begin moving to a new community on the mainland. The resettlement plan was initiated by the residents there more than a decade ago when they could no longer deny that the island couldn’t accommodate the growing population. Rising seas and intense storms are only making the predicament more dire.

Many of the older adults will opt to stay put. Some still don’t believe climate change poses a threat, but 70-year-old Pedro Lopez is not among them. Lopez, whose cousin interpreted for him during our Zoom interview, currently shares a small house with 16 family members and the family dog. He doesn’t plan to move. He knows Gardi Sugdub, translated as Crab Island, along with many others in the archipelago, is going underwater, but he believes it won’t happen within his lifetime.

The Indigenous Guna people have occupied these Caribbean islands since around the mid-1800s, when they abandoned the coastal jungle area near what is now the Panama-Colombia border to establish better trade and escape disease-carrying pests. Now, they are among the estimated hundreds of millions of people worldwide who by the end of the century may be forced to flee their land because of rising sea levels (SN: 5/9/20 & 5/23/20, p. 22).

In the Caribbean, sea level rise currently averages around 3 to 4 millimeters per year. As global temperatures continue to rise, it is expected to hit 1 centimeter per year or more by century’s end.

All of the islands of the San Blas archipelago will eventually be underwater and uninhabitable, says Steven Paton, who directs the Physical Monitoring Program at the Smithsonian Tropical Research Institute in Panama. “Some may need to be abandoned very soon while others not for many decades,” he adds.

Anthropologist Anthony Oliver-Smith of the University of Florida in Gainesville has studied people who are forced from their homes by disasters for more than 50 years. Around the world, he says, climate change has become a major driver of displacement, with people who have limited resources facing the worst of it.

The impacts of climate change — flooding, rising seas and erosion — are threatening the Tuvaluans in the South Pacific, the Mi’Kmaq of Prince Edward Island in Canada and the Shinnecock Indian Nation of New York. Half of some 1,600 remaining tribe members there still occupy a more than 300-hectare territorial homeland on Long Island surrounded by multimillion-dollar Southampton mansions.

The Guna relocation is being closely watched as a possible template for other threatened communities. What sets the Guna apart from many others is that they have a place to go.

Rising sea levels in Guna Yala

More than 30,000 Indigenous Guna inhabit the province now called Guna Yala, which includes the archipelago once known as San Blas and a strip of mainland. Most live on the islands, traveling back to the mainland to get water from the mouth of the river there, and in some cases to tend crops. Some of the islands sit several meters above average sea level, but the vast majority are uninhabited spits of land with palm trees, many only a meter or less above sea level.

So far, only the residents of Gardi Sugdub are included in the relocation plan.

The Guna people of the islands are sustained by the biodiversity there. The sea, mangroves and nearby mainland forests provide food, medicine and building materials. The men hunt and fish to provide seafood to the best restaurants in Panama City, and agriculture remains part of the economy. Guna communities elect traditional authorities known as sailas (“chiefs” in Guna) and argars (“chief’s spokesmen”), and they hold regular meetings to address community issues.

In recent decades, the Guna have moved toward an economy based on tourism and providing services to outsiders. They earn money supplying food, souvenirs and cultural artifacts to tourists but allow visitors to the islands only with prior approval from the sailas. Outsiders are not permitted to own property or operate businesses.

Carlos Arenas is an international human rights lawyer and an adviser on social and climate justice issues. When he visited Gardi Sugdub in 2014 as a consultant for Displacement Solutions, a nonprofit initiative focused on housing, land and property rights, he was tasked to assess the nascent relocation plans and provide recommendations. He was shocked to see the visible threat posed by the rising sea. “You cannot see much elevation,” Arenas says. “The level of exposure was extremely high, but they don’t see it necessarily that way. They have been living there for more than 170 years.”

Heliodora Murphy grew up on Gardi Sugdub and has watched the ocean rise higher each year. The 52-year-old grandmother doesn’t understand those who dismiss climate change in light of the growing physical evidence all around. Murphy, also speaking through an interpreter, recalls her father bringing rocks and sand from a river on the mainland to shore up pathways and keep their home dry.

Gardi Sugdub resident Pedro Lopez, left, plans to stay on the island, while Heliodora Murphy, right, has already picked out her new home on the mainland.COURTESY OF IVETTE N. ROGERS

Arenas says that some families face a daily struggle against the ocean. They build barriers that are immediately destroyed and have to be built again.

Some of the stopgap measures have been counterproductive, like filling in coral reefs to expand the land area. Reefs are a natural buffer against wave action, storm surges, flooding and erosion. Destroying them has only added to the peril.

Today, Murphy says, storm surges carry water into her small, ground-level home. “It’s very different than in the past,” she says. “The waves are so much higher now.” About two years ago, she decided she’d move with her family. “We can’t stay here.”

A history of autonomy

Historically, the Guna have had a level of autonomy rare among Indigenous people. When the Spanish conquistadors arrived in what is now Colombia and Panama, the Guna lived primarily near the Gulf of Urabá on the northern coast of Colombia. The two groups clashed violently, prompting the Guna to abandon the coastal border area and move north into the jungle of Panama near the Caribbean. By the mid-1800s, entire villages had relocated again, this time to the San Blas archipelago.

Panama declared its independence from Spain in 1821 and became a part of Gran Colombia. Throughout the 19th century, the Guna lived independently according to their customs. That changed in 1903 when Panama broke from Colombia. The new nation attempted to assimilate the people living on the archipelago.

But having escaped Spanish rule centuries earlier and avoided Colombian authority as well, the Guna resisted Panama’s acculturation efforts. When the Guna couldn’t achieve détente through other means, they launched an armed attack against the Panamanians in February 1925.

The United States, having occupied the Panama Canal Zone since 1903, had geopolitical interests in the region and threw its support behind the Guna. That support forced the Panamanian government into a negotiated peace that allowed the Guna to continue their way of life. In 1938, the Guna islands and adjacent coastline were recognized as a semiautonomous Indigenous territory, Guna Yala. The Guna have maintained control of that territory since.

The Guna find a new home

The Gardi Sugdub residents first broached the idea of relocation in 2010. “They basically ran out of room,” Oliver-Smith says.

He describes the Guna as the Indigenous people in Latin America who have been perhaps most successful in defending their cultural heritage, language and territory. They initiated the plans for resettlement and made arrangements among themselves to set aside 17 hectares of property on the mainland for these purposes. The land, within the Guna Yala territory, is near a school and health center being built by the Panamanian government.

The residents of Gardi Sugdub (the island is shown here in 2014) face overcrowding and rising seas. More than a decade ago, they initiated a plan to move more than 300 families to a new community on the mainland.ARNULFO FRANCO/AP PHOTO

When Guna leaders approached the government, the Ministry of Housing initially promised to build 50 houses on the parcel. But it remained just that — a promise — until around 2014, when the Guna began to speak publicly about their situation. News of their predicament caught the attention of Indigenous rights organizations and eventually Displacement Solutions, which turned to Arenas and Oliver-Smith to evaluate the situation and offer recommendations about the best way forward.

Following Displacement Solutions’ first report in 2014, Panama’s Ministry of Housing agreed to build 300 houses, along with the hospital and school. But Arenas, who until the COVID-19 pandemic started had visited Guna Yala every year or so, says progress remained slow, causing the Guna to question Panama’s commitment to the relocation. The Guna leveraged support from international groups and members of the Panamanian government to get the project moving. “They were the originators of the idea of resettlement,” Oliver-Smith says. “And they kept it alive.”

Arenas estimates that roughly 200 of the 300 houses in the new community are complete. The cost for the houses, which are being paid for by the Panamanian government, exceeds $10 million, and the Inter-American Development Bank has invested $800,000 in technical assistance. The new homes will have cement floors, bamboo walls, zinc roofs, running water and full electrification.

Before plans to relocate began, many Guna had already moved to cities including Panama City and Colón for school, work or simply to have more room. Arenas expects that many more people already living in mainland Panama will likely join their families in the new community. People on other Guna Yala islands will likely have to move eventually too.

Murphy has already picked out her two-bedroom home for her small nuclear family of seven. Two daughters moved to Panama City years ago, and she hopes to see them more. But at around 40 square meters, the homes may not accommodate the typical multigenerational, double-digit Guna families. Lopez plans to stay on the island, letting the younger generations live in the family’s new home on the mainland.

The Guna hope to retain their traditional customs through the move, including handiwork called wini and molas (examples shown).DIXON HAMBY/MOMENT/GETTY IMAGES PLUS

To ensure that the ethnic and cultural identities they fought to preserve are not lost in the move, the Guna plan to develop programs to teach traditions and culture to the resettled generations. But even on Gardi Sugdub, younger generations seem less inclined to practice the traditional customs — like making and wearing wini (vibrantly colored beads worn around the arms and legs) and molas (intricately designed fabric dresses that have become a symbol of Guna life and resistance to colonialism). Murphy began learning the craft when she was 6 years old. She spends two months constructing each ensemble, which she sells to tourists for $80.

Oliver-Smith is optimistic about the relocation plan but worries that the Panamanian government has repeated some mistakes that have doomed projects elsewhere by treating resettlement solely as a housing issue. “You don’t just pick people up and move them from point A to point B. It is a reconfiguring of a life of a people,” Oliver-Smith says. “It has political, social, economic, environmental, spiritual and cultural dimensions.”

As is often the case when Indigenous and rural communities relocate, Arenas says, the government failed to make the Guna equal participants in the design concept. “The Panamanian government is trying to build a Panama City neighborhood in the middle of a tropical forest,” he says. “They have not tried to save a single tree of this beautiful landscape…. They removed everything. They tried to flatten the land because it’s cheaper…. It’s also extremely hot there, and the building materials are hot.” This increases the risk of failure, he says, because the houses don’t match the environment.

But Murphy hopes everything will be better. The new village promises dry land and more space. And perhaps returning to the mainland the Guna occupied nearly 150 years ago will lead to a stronger connection to Guna historical culture and traditions.

Oliver-Smith says the Guna are facing the challenge of resettlement with an intact culture and language that he hopes will be a basis for maintaining cultural continuity. His time spent with the Guna has convinced him that, as disruptive and devastating as resettlement can be, the Guna relocating as a cohesive group are perhaps best equipped to emerge intact even if not unscathed.

“Carlos [Arenas] and I asked an old, retired saila if he thought resettlement would change the Guna,” he says. “He said, ‘No. Individuals may change out of choice, but our culture is eternal. It will never die.’ ” More

Baseball is the best sport in the world for numberphiles. There are so many stats collected that the analysis of them even has its own name: sabermetrics. Like in Moneyball, team managers, coaches and players use these statistics in game strategy, but the mountain of available data can also be put to other uses.

Researchers have now mined baseball’s number hoard to show that climate change caused more than 500 home runs since 2010, with higher air temperatures contributing to the sport’s ongoing home run heyday. The results appear April 7 in the Bulletin of the American Meteorological Society.

Many factors have led to players hitting it out of the park more often in the last 40 years, from steroid use to the height of the stitches on the ball. Blog posts and news stories have also speculated about whether climate change could be increasing the number of home runs, says Christopher Callahan of Dartmouth College (SN: 3/10/22). “But nobody had quantitatively investigated it.”

A climate change researcher and baseball fan, Callahan decided to dig into the sport’s mound of data in his free time to answer the question. After he gave a brief presentation at Dartmouth on the topic, two researchers from different fields joined the project.

That collaboration produced an analysis that is methodologically sound and “does what it says,” says Madeleine Orr, a researcher of the impacts of climate change on sports at Loughborough University London, who was not involved with the study.

The theorized relationship between global warming and home runs stems from fundamental physics — the ideal gas law says as temperature goes up, air density goes down, reducing air resistance. To see if home runs were happening due to warming, Callahan and colleagues took several approaches.

First, the team looked for an effect at the game level. Across more than 100,000 MLB games, the researchers found that a 1-degree Celsius increase in the daily high temperature increased the number of home runs in a game by nearly 2 percent. For example, a game like the one on June 10, 2019, where the Arizona Diamondbacks and Philadelphia Phillies set the record for most home runs in a game, would be expected to have 14 home runs instead of 13 if it were 4 degrees C warmer.

The researchers then ran game-day temperatures through a climate model that controls for greenhouse gas emissions and found that human-caused warming led to an average of 58 more home runs each season from 2010 to 2019. The analysis also showed that the overall trend of more home runs in higher temperatures goes back to the 1960s.

The team followed that analysis with a look at more than 220,000 individual batted balls, made possible by the Statcast system — where high-speed cameras have tracked the trajectory and speed of every ball hit during a game since 2015. The researchers compared balls hit in almost exactly the same way on days with different temperatures, while controlling for other factors like wind speed and humidity. That analysis showed a similar increase in home runs per degree Celsius as the game-level analysis, with only lower air density due to higher temperatures left to explain higher numbers of home runs.

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While climate change has “not been the dominant effect” causing more home runs, “if we continue to emit greenhouse gases strongly, we could see much more rapid increases in home runs” moving forward, Callahan says.

Some fans feel that the prevalence of home runs has made baseball duller, and it’s at least part of the reason that the MLB unveiled several new rule changes for the 2023 season, Callahan says.

Teams can adapt to rising temperatures by shifting day games to night games and adding domes to stadiums — the researchers found no effect of temperature on home runs for games played under a dome. But according to Orr, climate change may soon cause even more dramatic changes to America’s pastime, even with those adaptations.

Because the sport is susceptible to snow, storms, wildfires, flooding and heat at various points during the season, Orr says, “I don’t think, without substantial change, baseball exists in the current model” within 30 years.

Callahan agrees. “This sport, and all sports, are going to see major changes in ways that we cannot anticipate.” More

A form of lightning with a knack for sparking wildfires may surge under climate change.

An analysis of satellite data suggests “hot lightning” — strikes that channel electrical charge for an extended period — may be more likely to set landscapes ablaze than more ephemeral flashes, researchers report February 10 in Nature Communications. Each 1 degree Celsius of warming could spur a 10 percent increase in the most incendiary of these Promethean bolts, boosting their flash rate to about four times per second by 2090 — up from nearly three times per second in 2011.

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That’s dangerous, warns physicist Francisco Javier Pérez-Invernón of the Institute of Astrophysics of Andalusia in Granada, Spain. “There will be more risk of lightning-ignited wildfires.”

Among all the forces of nature, lightning sets off the most blazes. Flashes that touch down amid minimal or no rainfall — known as dry lightning — are especially effective fire starters. These bolts have initiated some of the most destructive wildfires in recent years, such as the 2020 blazes in California (SN: 12/21/20).

But more than parched circumstances can influence a blast’s ability to spark flames. Field observations and laboratory experiments have suggested the most enduring form of hot lightning — “long continuing current lightning”— may be especially combustible. These strikes channel current for more than 40 milliseconds. Some last longer than one-third of a second — the typical duration of a human eye blink.

“This type of lightning can transport a huge amount of electrical discharge from clouds to the ground or to vegetation,” Pérez-Invernón says. Hot lightning’s flair for fire is analogous to lighting a candle; the more time a wick or vegetation is exposed to incendiary energy, the easier it kindles.

Previous research has proposed lightning may surge under climate change (SN: 11/13/14). But it has remained less clear how hot lightning — and its ability to spark wildfires — might evolve.

Pérez-Invernón and his colleagues examined the relationship between hot lightning and U.S. wildfires, using lightning data collected by a weather satellite and wildfire data from 1992 to 2018.

Long continuing current lightning could have sparked up to 90 percent of the roughly 5,600 blazes encompassed in the analysis, the team found. Since less than 10 percent of all lightning strikes during the summer in the western United States have long continuing current, the relatively high ignition count led the researchers to infer that flashes of hot lightning were more prone to sparking fire than typical bolts.

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The researchers also probed the repercussions of climate change. They ran computer simulations of the global activity of lightning during 2009 to 2011 and from 2090 to 2095, under a future scenario in which annual greenhouse gas emissions peak in 2080 and then decline.

The team found that in the later period, climate change may boost updraft within thunderstorms, causing hot lightning flashes to increase in frequency to about 4 strikes per second globally — about a 40 percent increase from 2011. Meanwhile, the rate of all cloud-to-ground strikes might increase to nearly 8 flashes per second, a 28 percent increase.

After accounting for changes in precipitation, humidity and temperature, the researchers predicted wildfire risk will significantly increase in Southeast Asia, South America, Africa and Australia, and risk will go up most dramatically in North America and Europe. However, risk may decrease in many polar regions, where rainfall is projected to increase while hot lightning rates remain constant.

It’s valuable to show that risk may evolve differently in different places, says Earth systems scientist Yang Chen of the University of California, Irvine, who was not involved in the study. But, he notes, the analysis uses sparse data from polar regions, so there is a lot of uncertainty. Harnessing additional data from ground-based lightning detectors and other data sources could help, he says. “That [region is] important, because a lot of carbon can be released from permafrost.”

Pérez-Invernón agrees more data will help improve projections of rates of lightning-induced wildfire, not just in the polar regions, but also in Africa, where blazes are common but fire reports are lacking. More

The Climate BookGreta ThunbergPenguin Press, $30

The best shot we have at minimizing the future impacts of climate change is to limit global warming to 1.5 degrees Celsius. Since the Industrial Revolution began, humankind has already raised the average global temperature by about 1.1 degrees. If we continue to emit greenhouse gases at the current rate, the world will probably surpass the 1.5-degree threshold by the end of the decade.

That sobering fact makes clear that climate change isn’t just a problem to solve someday soon; it’s an emergency to respond to now. And yet, most people don’t act like we’re in the midst of the greatest crisis humans have ever faced — not politicians, not the media, not your neighbor, not myself, if I’m honest. That’s what I realized after finishing The Climate Book by Greta Thunberg.

The urgency to act now, to kick the addiction to fossil fuels, practically jumps off the page to punch you in the gut. So while not a pleasant read — it’s quite stressful — it’s a book I can’t recommend enough. The book’s aim is not to convince skeptics that climate change is real. We’re well past that. Instead, it’s a wake-up call for anyone concerned about the future.

A collection of bite-size essays, The Climate Book provides an encyclopedic overview of all aspects of the climate crisis, including the basic science, the history of denialism and inaction, and what to do next. Thunberg, who became the face of climate activism after starting the Fridays For Future protests as a teenager (SN: 12/16/19), assembles an all-star roster of experts to write the essays.

The first two sections of the book lay out how a small amount of warming can have major, far-reaching effects. For some readers, this will be familiar territory. But as each essay builds on the next, it becomes clear just how delicate Earth’s climate system is. What also becomes clear is the significance of 1.5 degrees (SN: 12/17/18). Beyond this point, scientists fear, various aspects of the natural world might reach tipping points that usher in irreversible changes, even if greenhouse gas emissions are later brought under control. Ice sheets could melt, raise sea levels and drown coastal areas. The Amazon rainforest could become a dry grassland.

The cumulative effect would be a complete transformation of the climate. Our health and the livelihood of other species and entire ecosystems would be in danger, the book shows. Not surprisingly, essay after essay ends with the same message: We must cut greenhouse gas emissions, now and quickly.

Repetition is found elsewhere in the book. Numerous essays offer overlapping scientific explanations, stats about emissions, historical notes and thoughts about the future. Rather than being tedious, the repetition reinforces the message that we know what the climate change threat is, we know how to tackle it and we’ve known for a long time.

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Thunberg’s anger and frustration over the decades of inaction, false starts and broken pledges are palpable in her own essays that run throughout the book. The world has known about human-caused climate change for decades, yet about half of all human-related carbon dioxide emissions ever released have occurred since 1990. That’s the year the Intergovernmental Panel on Climate Change released its first report and just two years before world leaders met in Rio de Janeiro in 1992 to sign the first international treaty to curb emissions (SN: 6/23/90).

Perversely, the people who will bear the brunt of the extreme storms, heat waves, rising seas and other impacts of climate change are those who are least culpable. The richest 10 percent of the world’s population accounts for half of all carbon dioxide emissions while the top 1 percent emits more than twice as much as the bottom half. But because of a lack of resources, poorer populations are the least equipped to deal with the fallout. “Humankind has not created this crisis,” Thunberg writes, “it was created by those in power.”

That injustice must be confronted and accounted for as the world addresses climate change, perhaps even through reparations, Olúfẹ́mi O. Táíwò, a philosopher at Georgetown University, argues in one essay.

So what is the path forward? Thunberg and many of her coauthors are generally skeptical that new tech alone will be our savior. Carbon capture and storage, or CCS, for example, has been heralded as one way to curb emissions. But less than a third of the roughly 150 planned CCS projects that were supposed to be operational by 2020 are up and running.

Progress has been impeded by expenses and technology fails, science writer Ketan Joshi explains. An alternative might be “rewilding,” restoring damaged mangrove forests, seagrass meadows and other ecosystems that naturally suck CO2 out of the air (SN: 9/14/22), suggest environmental activists George Monbiot and Rebecca Wrigley.

Fixing the climate problem will not only require transforming our energy and transportation systems, which often get the most attention, but also our economies (endless growth is not sustainable), political systems and connection to nature and with each other, the book’s authors argue.

The last fifth of the book lays out how we could meet this daunting challenge. What’s needed is a critical mass of individuals who are willing to make lifestyle changes and be heard. This could trigger a social movement strong enough to force politicians to listen and create systemic and structural change. In other words, it’s time to start acting like we’re in a crisis. Thunberg doesn’t end the book by offering hope. Instead, she argues we each have to make our own hope.

“To me, hope is not something that is given to you, it is something you have to earn, to create,” she writes. “It cannot be gained passively, through standing by and waiting for someone else to do something. Hope is taking action.”

Buy The Climate Book from Bookshop.org. Science News is a Bookshop.org affiliate and will earn a commission on purchases made from links in this article. More

Antarctica’s most vulnerable climate hot spot is a remote and hostile place — a narrow sliver of seawater, beneath a slab of floating ice more than half a kilometer thick. Scientists have finally explored it, and uncovered something surprising.

“The melt rate is much weaker than we would have thought, given how warm the ocean is,” says Peter Davis, an oceanographer at the British Antarctic Survey in Cambridge who was part of the team that drilled a narrow hole into this nook and lowered instruments into it. The finding might seem like good news — but it isn’t, he says. “Despite those low melt rates, we’re still seeing rapid retreat” as the ice vanishes faster than it’s being replenished.

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Davis and about 20 other scientists conducted this research at Thwaites Glacier, a massive conveyor belt of ice about 120 kilometers wide, which flows off the coastline of West Antarctica. Satellite measurements show that Thwaites is losing ice more quickly than at any time in the last few thousand years (SN: 6/9/22). It has accelerated its flow into the ocean by at least 30 percent since 2000, hemorrhaging over 1,000 cubic kilometers of ice — accounting for roughly half of the ice lost from all of Antarctica.

Much of the current ice loss is driven by warm, salty ocean currents that are destabilizing the glacier at its grounding zone — the crucial foothold, about 500 meters below sea level at the drilling location, where the ice lifts off its bed and floats (SN: 4/9/21).

Now, this first-ever look at the glacier’s underbelly near the grounding zone shows that the ocean is attacking it in previously unknown and troubling ways.

When the researchers sent a remote-operated vehicle, or ROV, down the borehole and into the water below, they found that much of the melting is concentrated in places where the glacier is already under mechanical stress — within massive cracks called basal crevasses. These openings slice up into the underside of the ice.

Even a small amount of melting at these weak spots could inflict a disproportionately large amount of structural damage on the glacier, the researchers report in two papers published February 15 in Nature.

These results are “a bit of a surprise,” says Ted Scambos, a glaciologist at the University of Colorado Boulder who was not part of the team. Thwaites and other glaciers are monitored mostly with satellites, which make it appear that thinning and melting happen uniformly under the ice.

As the world continues to warm due to human-caused climate change, the shrinking glacier itself has the potential to raise global sea level by 65 centimeters over a period of centuries. Its collapse would also destabilize the remainder of the West Antarctic Ice Sheet, triggering an eventual three meters of global sea level rise.

With these new results, Scambos says, “we’re seeing in much more detail processes that will be important for modeling” how the glacier responds to future warming, and how quickly sea level will rise.

A cold, thin layer shields parts of Thwaites Glacier’s underside

Simply getting these observations “is kind of like a moon shot, or even a Mars shot,” Scambos says. Thwaites, like most of the West Antarctic Ice Sheet, rests on a bed that is hundreds of meters below sea level. The floating front of the glacier, called an ice shelf, extends 15 kilometers out onto the ocean, creating a roof of ice that makes this spot almost entirely inaccessible to humans. “This might represent the pinnacle of exploration” in Antarctica, he says.

These new results stem from a $50 million effort — the International Thwaites Glacier Collaboration — conducted by the United States’ National Science Foundation and United Kingdom’s Natural Environment Research Council. The research team, one of eight funded by that collaboration, landed on the snowy, flat expanse of Thwaites in the final days of 2019.

The researchers used a hot water drill to melt a narrow hole, not much wider than a basketball, through more than 500 meters of ice. Below the ice sat a water column that was only 54 meters thick.

When Davis and his colleagues measured the temperature and salinity of that water, they found that most of it was about 2 degrees Celsius above freezing — potentially warm enough to melt 20 to 40 meters of ice per year. But the underside of the ice seems to be melting at a rate of only 5 meters per year, researchers report in one of the Nature papers. The team calculated the melt rate based on the water’s salinity, which reveals the ratio of seawater, which is salty, to glacial meltwater, which is fresh.

The reason for that slow melt quickly emerged: Just beneath the ice sat a layer of cold, buoyant water, only 2 meters thick, derived from melted ice. “There is pooling of much fresher water at the ice base,” says Davis, and this cold layer shields the ice from warmer water below. 

Those measurements provided a snapshot right at the borehole. Several days after the hole was opened, the researchers began a broader exploration of the unmapped ocean cavity under the ice.

Workers winched a skinny, yellow and black cylinder down the borehole. This ROV, called Icefin, was developed over the last seven years by a team of engineers led by Britney Schmidt, a glaciologist at Cornell University.

A remote-operated vehicle called Icefin was lowered down a borehole, through more than 500 meters of ice, to measure ocean currents and ice melting rates under Thwaites Glacier.Icefin/ITGC/Schmidt

Schmidt and her team piloted the craft from a nearby tent, monitoring instruments while she steered the craft with gentle nudges to the buttons of a PlayStation 4 controller. The smooth, mirrorlike ceiling of ice scrolled silently past on a computer monitor — the live video feed piped up through 3½ kilometers of fiber-optic cable.

As Schmidt guided Icefin about 1.6 kilometers upstream from the borehole, the water column gradually tapered, until less than a meter of water separated the ice from the seafloor below. A few fish and shrimplike crustaceans called amphipods flitted among otherwise barren piles of gravel.

This new section of seafloor — revealed as the ice thins, lifts and floats progressively farther inland — had been exposed “for less than a year,” Schmidt says.

Now and then, Icefin skimmed past a dark, gaping cleft in the icy ceiling, a basal crevasse. Schmidt steered the craft into several of these gaps — often over 100 meters wide — and there, she saw something striking.

Melting of Thwaites’ underbelly is concentrated in deep crevasses

The vertical walls of the crevasses were scalloped rather than smooth, suggesting a higher rate of melting than that of the flat icy ceiling. And in these places, the video became blurry as the light refracted through vigorously swirling eddies of salty water and freshwater. That turbulent swirling of warm ocean water and cold meltwater is breaking up the cold layer that insulates the ice, pulling warm, salty water into contact with it, the scientists think.

Schmidt’s team calculated that the walls of the crevasses are melting at rates of up to 43 meters per year, the researchers report in the second Nature paper. The researchers also found rapid melt in other places where the level ceiling of ice is punctuated by short, steep sections.

The greater turbulence and higher melt also appear driven by ocean currents within the crevasses. Each time Schmidt steered Icefin up into a crevasse, the ROV detected streams of water flowing through it, as though the crevasse were an upside-down ditch. These currents moved up to twice as fast as the currents outside of crevasses.

The fact that melting is concentrated in crevasses has huge implications, says Peter Washam, an oceanographer on Schmidt’s team at Cornell: “The ocean is widening these features by melting them faster.”

This could greatly accelerate the years-long process by which some of these cracks propagate hundreds of meters up through the ice until they break through at the top — calving off an iceberg that drifts away. It could cause the floating ice shelf, which presses against an undersea mountain and buttresses the ice behind it, to break apart more quickly than predicted. This, in turn, could cause the glacier to spill ice into the ocean more quickly (SN: 12/13/21). “It’s going to have an impact on the stability of the ice,” Washam says.

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This video, captured by a remote-operated vehicle called Icefin, shows the underside of Thwaites Glacier where it flows off the coastline of West Antarctica. Horizontal sections of the ice are smooth, indicating slow melting. But on steep ice surfaces — especially along the walls of deep cracks in the ice — the surfaces are scalloped, suggesting a much higher rate of melt, driven by turbulent swirling of warm, salty ocean water and cold, fresh meltwater. An example of the difference between those two surfaces is clearly visible from 0:11 to 0:13 in the video, when Icefin captures a scalloped vertical surface intersecting with a smooth horizontal one.

These new data will improve scientists’ ability to predict the future retreat of Thwaites and other Antarctic glaciers, says Eric Rignot, a glaciologist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., who assisted the team by providing satellite measurements of changes in the glacier. “You just cannot guess what the water structure might look like in these zones until you observe it,” he says.

But more work is needed to fully understand Thwaites and how it will further change as the world continues to warm. The glacier consists of two side-by-side fast-moving lanes of ice — one moving 3 kilometers per year, the other about 1 kilometer per year. Due to safety concerns, the team visited the slower lane — which still proved extremely challenging. Rignot says that scientists must eventually visit the fast lane, whose upper surface is more cracked up with crevasses — making it even harder to land aircraft and operate field camps.

The research reported today “is a very important step, but it needs to be followed by a second step,” the investigation of the glacier’s fast lane, he says. “It doesn’t matter how hard it is.” More