“Glacial lake outburst floods (GLOFs) pose a significant, climate change-related risk to the Mt. Everest region of Nepal. Given the existence of this imminent threat to mountain communities, understanding how people perceive the risk of GLOFs, as well as what factors influence this perception, is crucial for development of local climate change adaptation policies. A recent study, published in Natural Hazards, finds that GLOF risk perception in Nepal is linked to a variety of socioeconomic and cultural factors.”
“Amid the tropical Andes of Peru lies the Cordillera Blanca mountains, home to more tropical glaciers than anywhere else on Earth. This range provides water to some 95 million people. Rising temperatures over the last several decades, however, mean its once abundant glaciers are vanishing rapidly. That’s impacting the water supply of downstream communities, which are becoming increasingly dependent on soil moisture.
In an innovative study published in the journal Remote Sensing of Environment, researchers used drones to obtain high-resolution images of the valleys left behind as Cordillera Blanca’s glaciers recede. As the drones pass over these “proglacial valleys,” they can produce highly accurate maps of the soil moisture within the fields, rivers, wetlands, and meadows below.”
Heavy Snowfall and the Threat of Avalanches in Switzerland
“In January, officials dropped a series of controlled explosives to set off avalanches on mountains near the Moiry Glacier in southern Switzerland due to an increased amount of snowfall during the month. Communities are directed to stay inside (or preferably go into a basement) while the avalanches are triggered and close all shutters. Controlled avalanches are intended to reduce the severity of an avalanche as well as collateral debris from an avalanche, making it safer for adventurers to romp around the backcountry. The use of explosives to mitigate avalanche risk is used throughout many mountain communities, especially when areas experience above average snowfall.”
Robin Bell is a renowned geophysicist, the natural science which concerns itself with the physical processes and properties of the Earth. She has accumulated many accolades for her discoveries in Antarctica and Greenland, which include sub-glacial lakes, rivers that flow uphill, and a volcano beneath the West Antarctic ice sheet.
Bell is the current president of the American Geophsyical Union. The AGU is an international organization, which includes 62,000 scientists from 144 countries, making her the de facto top earth scientist in the world. The sensitive polar regions Bell studies are warming quickly, a symptom of climate change wrought by emissions from mankind’s activities. She is acutely aware of her personal contributions to the problem; her fuel-intensive polar research and a demanding travel schedule.
For many Americans, even those convinced of the science, climate change is a problem requiring collective action and thus excuse themselves from making personal sacrifices to reduce their personal emissions. Some say individual efforts to curb climate change, like eating less meat or cutting down on their air travel, are largely symbolic and too small to make any meaningful impact. It is notable, however, that the world’s leading earth scientist is not allowing collective inaction to absolve her of personal responsibility.
A Profile of Robin Bell
It is a frigid winter day at the Lamont-Doherty Earth Observatory on the Hudson River. Ice and salt still crystallize the pavement from the last storm, so Bell drove her silver Prius to work. I follow the sound of laughter on the first floor of the Oceanography building and run into Bell at the end of the hall. She offers me loose tea and invites her dog, Nara, a fluffy white Samoyed, to join us in her office overlooking the river.
Bell lives ten miles from the research center where she has worked to advance polar science over the past 35 years. According to Bell, the fossil fuel that supplements her hybrid vehicle will be her largest personal carbon expenditure until her flight to Asia later this year. In better weather, she cycles, or rides her electric bicycle.
Bell talked me through the weeks of her 2018 carbon emissions, which she tracked and charted as a line graph on her computer. She lamented the flight to Mexico that caused the line to spike and noted where it leveled out during carbon-negligible weeks where Bell and her husband, environmental law professor Karl Coplan, were sailing. “Nine tons. I’m still below average, but boy this year I’m going to blow it through the roof with travel.”
Bell’s role as the head of the AGU demands her presence at engagements in countries far from her home base in New York. But she will plan her trips with the precision of a military movement, combining multiple trans-Pacific trips to fulfill her presidential duties and to visit her daughter in California, into one condensed itinerary.
Her presidency, which began in 2019, comes as international community wrestles with how to quickly decarbonize the world economy. Staving off the worst effects of climate change requires immediate global-scale reduction in greenhouse gas emissions. The United States, the world’s largest per capita emitter, has sidelined itself from participating in the global effort, handicapped by its own recalcitrance.
Amid the political paralysis in America, debate has emerged among environmentalists and green-leaning citizens between individual versus collective action to curb emissions.
“I just want to set an example. If I am telling people this is an issue, I should be acting like it’s an issue.” – Robin Bell
In a December 2017 essay, David Roberts, a prominent climate and energy journalist for Vox, wrote “Go forth and be green. You will be happier and healthier. But do not mistake it for a solution to climate change. Only collective action and collective ingenuity can save us.”
Roberts’ view exposes a sentiment that is ubiquitous, even among many who study or write about earth science: that change is necessary on a scale far greater than could possibly be affected by any personal sacrifice, so why bother?
Roberts continued the thought in a recent Twitter thread: “Climate change is not an “environmental problem.” It’s far deeper than that. Solutions require basic changes in technology, law, and infrastructure, none of which is affected by individual behavior…Personal asceticism is largely irrelevant.”
The world’s top earth scientist disagrees.
“If we do not start acting like we care about our planet future’s then we can never move toward being a sustainable species,” Bell told me. “We cannot simply blame others and wait for some policy solution. All actions matter. Engaging all the strategies from individual action to carbon sequestration is essential to keep our planet, our home habitable.”
Living life in a manner that comports with her field of study is essential for Bell: “I just want to set an example,” she said. “If I am telling people this is an issue, I should be acting like it’s an issue.”
Bell usually stops by the farmer’s market on her way to the office. Buying from her local growers is an act of community for her. Bell and Coplan also belong to a community-supported agriculture group, whereby members purchase a share of the harvest of local farms to distribute the risk of farming.
Bell and Coplan have adopted a similar strategy for home energy supply, buying into community solar power. “It’s kind of like a CSA for solar,” Bell said. For Bell and Coplan, it is a work-around strategy, since their home is in the woods and shaded much of the day by tall trees. “We haven’t been willing to cut all the down trees that keep our house cool to get better solar.”
The pair ascribes to a Mediterranean diet; a mostly plant-based approach to food. They keep a garden, too. Bell primarily does the perennials and tends the bees, while Coplan oversees the annuals. Coplan also maintains a sustainable living blog and is the author of the forthcoming book “Live Sustainably Now: A Carbon-Sustainable Vision of the American Dream.” Last fall The Hill ran an op ed where Coplan urged Americans to make fundamental lifestyle changes, “there is no argument for inaction…collective action starts with individual action.”
Their shared passion is sailing, a wind-powered hobby. Bell and Coplan constructed a boat together while they were students at Middlebury College in Vermont. With their two children, they have completed multiple transAtlantic voyages and have planned a circumnavigation of the globe. They also maintain a cabin upstate, completely off the grid, ski-in ski-out, with plug-ins to charge their vehicle. “It’s just like a boat,” Bell says. “The batteries are in the floor. It’s a composting toilet. Just a wood stove for heat.”
I asked Bell about the last time she used a plastic bag. Expecting a figure on the order of decades, she replied, “I still read the regular old paper and they come in plastic bags when they are hand-delivered to your house.” Bell is hyper-aware of her impact, but she is not ascetic in her lifestyle. Supporting print journalism, for Bell, is a concession which outweighs the plastic cost. “On my list of things to worry about, plastic bag use isn’t my highest. My carbon use is. I’m much more worried about that. People get worried about plastic straws and don’t have a bigger vision of what their impact is on the planet.”
On fellow earth science leaders, Bell said, “We should be showing that we are taking sustainability seriously. Very few people are being reflective. Maybe people have done something like dropped beef. Some of my favorite friends here, that’s what they’ve done. But they still fly to an island several times a year.”
Bell proudly points to the new AGU headquarters, the flagship building of science, as an example of what can be accomplished on a macro level. It is the first renovated net-zero building in Washington, DC. It uses rooftop solar, a green wall, auto-tinting glass, and a sewer heat exchange system to offset the energy it uses. “It’s showing what you can do as an individual. This is how we start to say what the future can look like and have it be a positive view.”
Mendenhall Glacier, near Alaska’s capital city of Juneau, is one of the most visited and oft-photographed glaciers in the United States. Kevin Lyons, an Alaska-based adventurer, uses his lens to offer a fresh angle on Mendenhall. Lyons is a self-described “photography enthusiast with a passion for travel and the outdoors.”
Dirt and cryoconite deposits on the ice surface inhibit the glacier’s ability to reflect solar radiation. Melt pools form on the ice surface, accelerating ablation by creating pores that allow water to penetrate the glacier.
Mendenhall’s retreat is well-documented, partly thanks to time lapse imagery provided by scientific cameras, like the one pictured below. The 2012 film, Chasing Ice, highlighted Mendenhall’s retreat to effect of global warming on the planet’s glaciers.
Mendenhall’s famous ice caves, pictured below, have collapsed since Lyons visited in 2014. A Frequently Asked Question on the U.S. Forest Service website addresses the rumor that ice caves exist at Mendenhall: “There have been several ice caves in past years, but the cave that appears in many recent internet photos has collapsed and disappeared. It was located along the west flank of the glacier but the ice has completely melted out of that area and no other caves are present.”
An indirect benefit for visitors and residents of Juneau is Lake Mendenhall, which did not exist prior to 1930. The lake formed due to excessive melt. The tongue of the glacier is expected to retreat to the point where it no longer terminates in the lake itself. According to Lyons, when the ice surface freezes just right “the hockey games out there are epic.”
This week’s video digests the sobering findings of the Hindu Kush Himalaya assessment. The montage was published by the International Center for Integrated Mountain Development (ICIMOD), one of the institutions responsible for compiling the report. As GlacierHub reported last week, the assessment is likely the most comprehensive climate assessment of the area: It includes input from over 300 experts, researchers, and policymakers.
The video describes the effects of climate change on the Third Pole, as the Himalaya is often called, including the rapid melting of glaciers. It conveys second-order effects on downstream human populations and ecology, which depend heavily on glacial runoff to support the region’s rivers. The major watersheds of southern Asia are fed by the melt from the Hindu Kush Himalaya region, which supports water, food, and energy needs for nearly two billion people.
GlacierHub also reported on the threat to hydropower development in the region posed by climate change.
The video appears during a week in which climate change received significant coverage in the United States, owing to the rollout of the Green New Deal proposal and a skeptical tweet about climate change from President Trump.
The video underscores the need for immediate action to stave off the worst effects of climate change in the sensitive region. In it, Asuncion Lera St. Clair, senior principal scientist at the Climate Action Program, suggests the comprehensive assessment “might be the beginning of a process of uniting the countries of the Hindu Kush Himalayas around what the science says needs to happen.”
Rep. Alexandria Ocasio-Cortez (D-NY) and Sen. Ed Markey (D-MA) introduced February 7 a resolution laying out the broad brushstrokes of a so-called Green New Deal. The announcement comes after the November 2018 midterm elections, when Democrats gained a majority in the House of Representatives. The Green New Deal framework aims to address the polarizing issue of climate change in the United States.
The resolution proposes a multiplicity of initiatives, the most transformative of which is the decarbonization of the US energy system. It also aims to add jobs and boost the economy while addressing the social consequences that come with such a reformation.
While the idea of a Green New Deal has existed for a decade, Ocasio-Cortez campaigned on a massive public-sector effort to address climate change. The idea has gained traction among a wide array of Congressional Democrats and most leading Democratic presidential contenders.
“The Green New Deal Resolution’s purpose is to define the scope of a climate solution,” Ocasio-Cortez said on Twitter. “We’ve defined the scope and where we want to go. Now let’s assess and collaborate on projects.”
The Green New Deal resolution references the UN Intergovernmental Panel on Climate Change’s October 2018 special report on global warming of 1.5°C and calls for the cessation of US fossil fuel use by 2030.
The deteriorating state of the world’s glaciers has framed in many ways perceptions of climate change. An NPR news article on the Green New Deal led with a reference to the hollowing Thwaites Glacier in Antarctica, whose collapse might raise sea levels by more than half a meter. Thwaites received recent attention in the news as it perches precariously on a sill in West Antarctica. Glacier retreat also featured prominently in the IPCC 1.5°C report, the US Fourth National Climate Assessment, and the recent Hindu-Kush Himalaya Assessment.
During the run-up to the 2016 Democratic primary, GlacierHub found that Sen. Bernie Sanders scored two percentage points higher, on average, in counties with glaciers than he did across the entire state of Wyoming.
Glaciers are part of the iconography of the American West and glacier-related tourism is central to the economies of glacier regions. In 2017, Glacier National Park in Montana drew over one million visitors in the month of July alone. The National Parks Service reported Alaska’s parks, which are largely glaciated, added $1.3 billion to that state’s economy in 2018.
Given the incentive to preserve the economic and ecological benefits of glaciers for US glacier regions, GlacierHub has surveyed support for the Green New Deal among glacier-state Senators and members of the House that represent glacier districts.
Of the twenty senators from the ten glaciated states in the US, only three have officially stated their support: Oregon’s Democratic Sens. Jeff Merkley and Ron Wyden, and California’s Kamala Harris, a Democrat who also announced her candidacy for president.
In the House,18 members represent districts with glaciers—and just six have announced their support.
Rep. Joe Neguse (CO-02), whose district contains all 14 named glaciers in Colorado, co-sponsored the Green New Deal resolution. “There is no longer a debate about whether climate change is real, the only conversation left is how we reverse its course,” Neguse said in a press release. “We do not have time to wait. We are the generation that will heal our planet.”
Rep. Jared Huffman (CA-02), whose mostly rural district includes the glaciers and icefields of Trinity Alps Wilderness, also signed on.
In the Pacific Northwest, glaciers and political lines get complicated. The representative of the district that includes Seattle, Pramila Jayapal (WA-07), is in support of the Green New Deal. Seattle lies within view of Mount Rainier, a glacier peak in the Cascade Range, though the district itself is glacier-less. But in one of the more vexing nonconformities, the representative of the district containing the glacier peak itself, Democrat Kim Schrier (WA-08), has not announced support. Washington is the most-glaciated state in the continental US, and yet none of the representatives of glacier districts—of which three out of four are represented by Democrats—have endorsed the Green New Deal. Representatives from those three Democratic districts did not provide GlacierHub with comment.
While Washington state was the most confounding, perhaps no region exhibited political division more starkly than Oregon. District boundaries in Oregon run along the spine of the Cascade Range, effectively splitting glaciated peaks between districts. OR-3 and OR-4 lie on the west side of the mountains. Representatives for those districts have endorsed the Green New Deal. OR-1, in western Oregon, also endorsed but it was excluded from GlacierHub’s analysis since the district lacks any glaciers. But the representative for OR-02, which comprises the entirety of eastern Oregon, from its southern border to the north, has not. The district, which is rural and reliably Republican, has been represented by Greg Walden since 1998. On Walden’s website, he appears draped in an American flag, superimposed in front of Oregon’s glaciated Three Sisters peaks.
Walden is the top Republican on the House Energy and Commerce Committee. Asked about the lack of support for a Green New Deal, Walden’s communications director referred GlacierHub to his remarks at an event last week where Walden held a glass jar of ash as a prop and harped on the need for better forest management to combat climate change.
America’s glaciers are in a state of retreat. “It’s inevitable that we will lose them all over the next few decades,” Daniel Fagre, a US Geological Survey scientist, told the Guardian. “The Colorado glaciers started melting before Montana’s and while there are larger glaciers in the Pacific Northwest that will hold on longer, the number vanishing will steadily grow until none are left.”
For now, political division in the US is obstructing efforts to address climate change. Barbara Brower, a geography professor at Portland State University, commented on Oregon’s divided support: “What could begin to change hearts and minds is growing awareness downstream from glaciers—in those intermountain red states—that no glaciers means no glacier-mediated summer streamflow.”
Before his appearance at the UN, Kurtyka joined Columbia faculty and students for a round-table discussion, hosted by Columbia’s Center on Global Energy Policy (CGEP) and co-sponsored by the Committee on Global Thought. Kurtyka gave opening remarks on the achievements of COP24, including a detailing of the challenge of forming international consensus. A discussion followed, which was moderated by Jonathan Elkind, CGEP Fellow and Senior Research Scholar. The conversation centered on climate change issues, including climate-related disasters on international peace and security and the recently held COP24, which is the 24th annual meeting of signatories to the UN Convention on Climate Change.
Kurtyka, who presided over COP24, gained diplomatic fame for his triumphant leap off the table at the closing ceremony in Katowice. COP24 came down to an 11th hour resolution, as many recent COPs of significance, like COP15 in Copenhagen and COP21 in Paris, have tended to do. The result was the so-called Katowice Rulebook, which operationalizes the 2015 Paris Agreement on Climate Change. Kurtyka praised the Rulebook, which he said “gave life to the Paris Agreement,” providing clarity on how, when, and according to which formula, all the countries of the world must act to achieve their pledged goals.
Central to the Katowice Rulebook is the concept of a “just transition,” whereby countries address social consequences of their shifts toward low-carbon economies.
In high mountain regions, glacial melt is a source for hydropower, a crucial component for many countries to achieve clean energy goals. Runoff from glaciers is also a chief supply for irrigation and clean drinking water. Tension exists in some glacier-fed basins, such as the Indus River, which lies between India and Pakistan—two countries where deep-seated animosity runs high. As glaciers near peak melt in coming decades, these pressures are unlikely to ease.
Kurtyka acknowledged the existential threat climate change poses and its potential to “create inflammatory ground where conflict can breed.”
A GlacierHub reporter asked Kurtyka about the challenges facing countries transitioning to renewable energy, particularly those dependent on meltwater from glaciers. “We have right now more climate and environment refugees than war refugees in the world,” Kurtyka replied. “With big rivers being exhausted, and also polluted enormously, we should expect, unluckily, lots of drama in this regard. Whether we can do something about it, I hope so. It might be extremely painful.”
The following day, at the UN Security Council, on which Poland currently holds a rotating seat, Kurtyka discussed tools for defusing potential climate-induced instabilities. He stressed the importance of conflict anticipation and prevention by equipping nations with early warning information gathering systems, aimed especially at states predisposed to such risks. One such exposed country is the Central Asian nation of Kazakhstan. The Kazakh representative, Kanat Tumysh, warned of his country’s increasing vulnerability due to glacial melt, which threatens to exhaust the region’s irrigation and drinking water by 2050.
At the meeting, Pavel Kabat, Chief Scientist at the World Meteorological Organization noted “the short-term effects of leaving glacier melt unchecked include increased flooding.” Kabat added: “The long-term threats will affect water supplies for millions of people.” The WMO chief’s comments marked the first time the international organization has briefed the Security Council on climate and extreme weather issues.
In 2017, a UN Security Council resolution recognized the adverse effect of climate change on political stability. Addressing the threat, though, has been typically left to other bodies like the UN Development Program.
The UN Security Council climate security meeting marks a turning point in the evolution of the way the international body regards climate change. No longer is climate change perceived as a concern limited to development and well-being, but is increasingly viewed as an immediate threat to peace and stability. At the meeting, the WMO chief announced that a position had been established at UN Headquarters for a dedicated WMO officer, an indication of the Security Council’s seriousness. The officer will provide expert information to UN strategic decision makers.
As one scrolls through the story, images transition from an aerial shot of a person descending the Tuyuksu Glacier to ablation measurements on the ice and a computer-generated graphic documenting the 60-year-long retreat of the glacier.
The story also takes a viewer to the glacier’s meltwater, where scientists gauge stream flow and analyze samples that reveal the meltwater’s source. The story pans across the Tibetan Plateau, as well as the Himalayan and Karakoram ranges.
Millions of inhabitants are dependent on Kazakhstan’s Tuyuksu Glacier for a dependable supply of water, according to the story, highlighting the impacts of climate change.
From Secrets of the Ice: The recovery of a small blunt arrow, radiocarbon-dated to Late Antique Little Ice Age, is a testimony to the importance of hunting during this period. Due to its small size, it is very likely to be a toy arrow. From a young age, children had to practice and master the art of bow-and-arrow. It was essential for survival, especially during harsh climatic conditions. The toy arrow was found in the glaciated mountain pass at Lendbreen in Breheimen National Park, southern Norway. The unlucky child probably lost it in the snow and thought it was gone forever. Not so, the ice preserved it for 1,400 years.
Read about this find and more glacier archaeology here.
Counting on NASA’s ICESat-2
From NASA: NASA’s most advanced laser instrument of its kind launched into space earlier this fall. According to the agency, the Ice, Cloud and land Elevation Satellite-2, or ICESat-2, provides critical observations of how ice sheets, glaciers and sea ice are changing, leading to insights into how those changes impact people where they live.
Glaciers on Svalbard Survived the Holocene Thermal Optimum
From Quaternary Science Reviews: “About 60% of Svalbard is covered by glaciers today, but many of these glaciers were much reduced in size or gone in the Early Holocene… Relative sea level has been rising during the last few millennia in the north and western parts of Spitsbergen, while land still emerges in the remaining part of Svalbard. Here we show that this sea level rise in the northwest is caused by the regrowth of glaciers in the Mid- to Late Holocene that slowed down, and even reversed, the post-glacial isostatic uplift and caused the crust to subside over large areas of Spitsbergen.”
This week’s video features the passion project of Quechua activist Irma Alvarez to preserve the Quechua tradition through orality and writing. Quechua refers to the original group of languages spoken by the Incan Empire in the Andes Mountains. When the Spanish arrived in the early 16th century, use of the language was suppressed as the indigenous groups were indoctrinated to Catholicism and the Spanish language. Quechua is a linguistic family wherein distinct dialects vary from community to community.
Despite the lack of printed material written in the Quechuan language, indigenous peoples clung to their mother tongue. It is estimated around ten million people still speak it across five South American countries today. Without literacy, however, the language is vulnerable to extinction. Alvarez is on a mission to teach Quechuan speakers how to read and write in their native language by increasing access and availability of printed materials. The Quechua Alliance in the United States hosts an annual meeting as part of the effort to preserve the culture of the high Andes by expanding the availability of the Quechuan oral tradition. The video has English subtitles.
The discovery of an impact crater in remote northwestern Greenland may resolve a major climate history question: what caused the planet to suddenly cool around 12,800 years ago? In a new study published last month in the journal Science Advances, the researchers are careful not to make claims about the larger implications of the find. But details, including the size and approximate timing of the impact, offer much to consider about what triggered Earth’s last sudden climate change.
The impact crater was discovered beneath Hiawatha Glacier, under more than a kilometer of ice. Hiawatha is among the largest impact craters ever discovered on Earth, as well as the northernmost and first to be located under ice. Modern geospatial technology has enabled the Earth’s surface to be thoroughly mapped, leaving significant undiscovered features either deep under the sea or beneath ice, like Hiawatha. That a striking and visible geologic feature of Hiawatha crater’s magnitude had yet to be located makes the find even more remarkable.
The initiative to map the crater was led by the intuition of principal author, Kurt Kjær, a glacial geologist at the University of Copenhagen and curator at the Natural History Museum of Denmark. Kjær wondered whether a connection might exist between an anomalous circular ice pattern he observed in satellite images of the Greenland ice sheet and an iron meteorite on display at the museum where he parks his bicycle.
To pursue his hunch, Kjær needed to know what was under the ice. Joe MacGregor, a glaciologist with the NASA Goddard Space Flight Center, unearthed archival imagery from Operation IceBridge. The temporary mission collected critical data used to predict the response of the Earth’s polar ice to climate change and sea-level rise. NASA assembled the operation after an ice monitoring satellite malfunctioned in 2009, bridging the gap until the successor satellite could be launched in September 2018. The aircraft often operated out of Thule Air Base, near Hiawatha. It often activated its instruments in test mode and happened to overfly the impact site on its flight path to the polar ice cap, adding a layer of serendipity to Kjær’s discovery. “Without Operation IceBridge the crater might’ve gone undiscovered for even longer than it did,” MacGregor told GlacierHub. Lucky or not, Kjær had mounted enough evidence to make his case.
A foundation backed by Copenhagen brewery, Carlsberg, funded the mission. A Basler BT-67 aircraft with a state-of-the-art ice-penetrating radar made three flights in May 2016, to map the suspected location. Kjær’s hunch was correct. The radar revealed a massive crater under the ice, suggesting an extraterrestrial impact. Measuring over 31 kilometers in diameter, the imprint left by the impact is among the largest on the planet, big enough to comfortably hold the city of Paris. Most similar-sized craters on Earth have changed much over time, many eroded to the point of unrecognizability. While ice tends to preserve organic material well, the pressure and grinding weight of ice scours topography. Beneath Hiawatha, the disheveled ice still bore signs of the cataclysm. At the bottom of the crater, classic impact characteristics, like central uplift features, were also apparent.
Recognizing the need for conclusive evidence to solidify his impact finding, Kjær visited Hiawatha later in the summer of 2016. In the outflow of the glacier, he found what he was looking for; tektites, a natural glass formed by meteoric impacts, and shocked quartz. Shocked quartz is only found in post-nuclear blast craters or extraterrestrial impact sites, like the Yucatan’s Chicxulub crater, whose impactor caused the mass extinction that killed off the dinosaurs. The Hiawatha crater’s crisp impact features and disrupted ice indicate it collided with the Earth at a much more recent date, perhaps as recent as the last Ice Age.
Could the Impact Have Triggered Sudden Climate Change?
The potential timing of the impact might be the greatest significance of the discovery. The Earth’s climate fluctuates between glacial and relatively warm interglacial periods, like the present. But as the planet thawed from the last ice age, it abruptly stopped warming, and cooled for over a millennium. For decades, climatologists theorized possible causes for this return to near-glaciation, known as the Younger Dryas. The period is named for an Arctic-alpine flower, Dryas octopetala, whose pollen is found in abundance in ice cores from the era. Some scientists believe Younger Dryas climate reversal may have been triggered by an event around 13,000 years ago. But the lack of physical evidence to support an impact hypothesis left the door open for a variety of theories.
A popular hypothesis for the cause of the Younger Dryas period is a sudden influx of melt water into the North Atlantic Ocean. The fresh water would create a stable surface layer, that would both slow the ocean circulation and freeze easily. An impact like the one that caused the Hiawatha crater would turn enough ice into fresh water to suppress the North Atlantic cycle and halt the warming. The timing seems about right.
Wally Broecker, known as the “Grandfather of Climate Science,” is a geoscientist at Columbia University’s Lamont-Doherty Earth Observatory. Among many climate firsts, Broecker coined the term “global warming” and was the first to recognize the global Ocean Conveyor Belt, a temperature and salinity-driven cycling of deep ocean water. In a 1989 paper published in Nature, Broecker theorized that the Younger Dryas period, and other periods of cooling like it, was triggered by the reorganization of deep ocean circulation — a critical process for modulating the Earth’s climate.
James Kennett is a marine geologist at the University of California, Santa Barbara, and one of Broecker’s co-authors of the 1989 paper. Kennett told Science, “I’d unequivocally predict that this crater is the same age as the Younger Dryas.” The impact would align with Kennett’s theory that a cosmic event precipitated the Younger Dryas cooling period. But, according to Broecker, the slowdowns of the conveyor belt are the effect of internal oscillation of the ocean system, independent of any impact event. In other words, though a meteor collision may have pre-triggered a cooling period, the Younger Dryas would have happened with or without an impact.
Broecker explained to GlacierHub, “I’m not convinced this caused the Younger Dryas. If you look at the record of Greenland ice cores, they happen over and over again,” Broecker said, referring to the Earth’s cycles of glaciation. “You can say the Younger Dryas was unique — it was triggered by an impact and all the others were just an internal oscillation.”
The location of the crater on the edge of Greenland also gave Broecker reason to doubt the impact-trigger for Younger Dryas, “I don’t think it could have melted that much ice,” he said. There are also other uncertainties regarding the impact, for example, the lack of evidence in deep ice cores taken elsewhere in Greenland. “That’s a problem,” Broecker said, referring to the absence of ejecta in the ice cores.
Whether or not ejecta would be present, however, depends on the angle of impact. Jay Melosh, from Purdue University’s Department of Earth, Atmospheric and Planetary Sciences, approached the question with similar restraint. He cautioned against making conclusions about the impact before a core is drilled and recovered, telling GlacierHub, “It will only be proved by drilling through the ice and demonstrating that the basin contains impact metamorphosed rock.”
While the slowdown of ocean circulation may have occurred independent of an impact, effects on biodiversity and humans would be tied to an impact. The Paleo-Indian Clovis culture and megafauna, like the woolly mammoth, are believed to have disappeared around the onset of the Younger Dryas. Until a core can be taken from Hiawatha, down to the impact-melted rocks, uncertainty regarding the timing will remain.
The study remains silent on questions about ocean circulation, providing the more general conclusion, “based on the size of the Hiawatha impact crater, this impact very likely had significant environmental consequences in the Northern Hemisphere and possibly globally.” It hints at forthcoming research and potentially a global quest for further evidence of the Hiawatha impact. Referring to the Younger Dryas impact theorists, Broecker said, “now people will renew the hunt.” In the quest to cross-reference the impact crater with paleoclimate evidence around the world, Hiawatha glacier might become one of the planet’s most significant. As mankind pushes Earth’s system toward the brink, understanding the planet’s most documented, sudden climate change, the Younger Dryas, becomes ever more urgent.
This week’s Photo Friday features a structure common to most glaciers. Foliation is layering in glacier ice that has distinctive crystal sizes and/or bubbles. Typically, foliation is caused by stress and deformation as a glacier grinds over uneven terrain, but it can also originate as a sedimentary feature.
According to a 1977 study published in the journal Tectonophysics, foliation in glaciers depends on the climate of the glacier. Temperate glaciers, for example, are defined by three types of ice (classified according to texture). Most abundant is a coarse-grained, bubble-rich ice, comprising two-thirds of the total ice exposed at the glacier surface. About one fifth of glacier ice is of a slightly larger, coarse clear variety, while the remainder is fine-grained and bubble-rich. In colder glaciers, such finer-grained ice is most common.
The stonefly is the largest animal inhabiting the glaciers of Patagonia. What the inch-long insect eats and excretes on the ice is central to the overall glacier ecosystem. Also known as the Patagonian Dragon, the stonefly occupies a near-apex position in the truncated glacier food chain. Stonefly larvae develop in glacial meltwater pools, where the larvae spends most of its life as a waterbound nymph, consuming algae, fungi, and other small inhabitants found in cryoconite sediments. The wingless adults wander the ice surface in search of food and mating opportunities. Despite their significant influence on glacier biogeochemical cycles, glacier invertebrates like the stonefly and their associated bacteria remain understudied. New research published in the journal Environmental Microbiology provided the first look at the genetics underlying the gut microbiome of stonefly nymphs.
The research team, comprised of Japanese and Chilean scientists, traveled by horseback and camped at Tyndall Glacier in Chile, collecting samples for analysis in a Tokyo laboratory. The team were surprised to find some bacteria in the stonefly gut were not present on the glacier surface. Not only was the bacteria absent from the surface of the Tyndall Glacier, but they were also distinct from bacteria catalogued in other glacier environments, indicating a symbiotic relationship between the Patagonian stonefly nymph host and its gut bacteria. The stonefly nymph provides an enriching gut environment and in turn the bacteria aids in the insect’s nutrition and material cycle of the glacier environment.
Insects and animals, including humans, host a variety of microorganisms in their digestive tracts. These microorganisms and other bacteria, called gut flora, help perform a variety of functions critical to the health of their host. For example, humans lack enzymes necessary to break down certain fibers, starches, and sugars. Our gut flora keeps us healthy and enables us to ingest a wide range of foods we would otherwise be unable to digest. Similarly, the stonefly’s gut community enables it to benefit from seemingly nutritionless cryoconite sediments.
According to Takumi Murakami, from Japan’s National Institute of Genetics and principal author of the study, glacier stonefly nymphs and their gut bacteria likely drive the decomposition of organic materials on the glacier. The gut bacteria-invertebrate symbiosis may even be a common phenomenon in glacier ecosystems beyond Patagonia. Understanding the role of high trophic level invertebrates, like the stonefly, and their bacteria in glacier ecosystems is key to understanding the big picture of glacier nutritional networks.
Japanese scientists have compiled a significant body of research on invertebrates and their gut flora, particularly those inhabiting glaciers. In 1984, Japanese researcher Shiro Kohshima documented a novel discovery on a visit to the Yala Glacier in Nepal; a cold-tolerant midge. Later he visited Patagonia to examine the glacier-indigenous insects of the region. Kohshima enlisted collaborators, who in turn brought their students, which has resulted in the present day team of glacier-insect specialists, including Murakami. Their diligence in studying glacier ecosystems has produced a prolific body of published work, helping fill knowledge gaps at the headwaters of organic decomposition.
Further underscoring the importance of the research, Murakami told GlacierHub, “Recent studies suggested that glacier ecosystems are the source of nutrition for downstream soil, river, and ocean ecosystems.” Were it not for the bacteria inhabiting the gut of the Patagonian Dragon, the organic matter would not be processed, and thus would not contribute to the glacier or downstream ecosystems.
Murakami adds, “Since glacier environments are susceptible to climate change, it is essential to accumulate the knowledge on the current glacier ecosystems for future studies, otherwise we will lose the opportunity.” Murakami’s concern is not unfounded. In the U.S., the stonefly is the poster child of understudied species that are quickly disappearing due to rapidly changing habitats. Petitions listing two species of stonefly under the Endangered Species Act are under consideration.