Roundup: Pre-Columbian Land Use, Trump in Tongass, and Greenland’s Ice Sheet

The Inca’s sustainable land use practices

From Quaternary Science Reviews:

“The extent of pre-Columbian land use and its legacy on modern ecosystems, plant associations, and species distributions of the Americas is still hotly debated. To address this gap, we present a Holocene palynological record (pollen, spores, microscopic charcoal, SCP analyses) from Illimani glacier with exceptional temporal resolution and chronological control close to the center of Inca activities around Lake Titicaca in Bolivia. Our results suggest that Holocene fire activity was largely climate-driven and pre-Columbian agropastoral and agroforestry practices had moderate (large-scale) impacts on plant communities. Unprecedented human-shaped vegetation emerged after AD 1740 following the establishment of novel colonial land use practices and was reinforced in the modern era after AD 1950 with intensified coal consumption and industrial plantations of Pinus and Eucalyptus. Although agroforestry practices date back to the Incas, the recent vast afforestation with exotic monocultures together with rapid climate warming and associated fire regime changes may provoke unprecedented and possibly irreversible ecological and environmental alterations.”

Read the article here.

Lake Titicaca (Source: Wikimedia Commons)

Trump proposes logging nearby Alaskan glaciers

From the Washington Post:

“Politicians have tussled for years over the fate of the Tongass, a massive stretch of southeastern Alaska replete with old-growth spruce, hemlock and cedar, rivers running with salmon, and dramatic fjords. President Bill Clinton put more than half of it off limits to logging just days before leaving office in 2001, when he barred the construction of roads in 58.5 million acres of undeveloped national forest across the country. President George W. Bush sought to reverse that policy, holding a handful of timber sales in the Tongass before a federal judge reinstated the Clinton rule.

Read the article here.

A view of Mendenhall Glacier, which lies in Tongass National Forest (Source: Wikimedia Commons)

Greenland ice sheet mass balance

From GEUS Bulletin:

“The Programme for Monitoring of the Greenland Ice Sheet (PROMICE) has measured ice-sheet elevation and thickness via repeat airborne surveys circumscribing the ice sheet at an average elevation of 1708 ± 5 m (Sørensen et al. 2018). We refer to this 5415 km survey as the ‘PROMICE perimeter’ (Fig. 1). Here, we assess ice-sheet mass balance following the input-output approach of Andersen et al. (2015). We estimate ice-sheet output, or the ice discharge across the ice-sheet grounding line, by applying downstream corrections to the ice flux across the PROMICE perimeter.”

Read the article here.

A helicopter takes off from the Greenland Ice Sheet. (Source: Wikimedia Commons)

Read More on GlacierHub:

What the 2018 State of the Climate Report Says About Alpine Glaciers

The Funeral for Iceland’s OK Glacier Attracts International Attention

Park Officials Remove Signs Warning That Some Glaciers Will Disappear by 2020

Please follow, share and like us:
error

Photo Friday: Images of Europe’s July Heat Wave

Temperature records fell one after another in Europe last week with five countries—Great Britain, Belgium, the Netherlands, Germany, and Luxembourg—registering record highs.

A study conducted by World Weather Attribution concluded that temperatures during the hot spell would have been 1.5-3 degrees Celsius cooler if not for the additional warming brought about by human-caused climate change.

Rank of annual maximum temperatures observed in Europe in 2019 compared to 1950 –2018, based on the E-OBS data set (Haylock et al., 2008, version 19, extended with monthly and daily updates to 30 July 2019). This figure is made with preliminary data and should be taken with caution as some measurements are not yet validated. (Source: World Weather Attribution)

Video posted to Twitter shows how rising temperatures are impacting Europe’s alpine glaciers. Severe-weather.EU posted footage of a massive mudslide barreling down a mountainside on July 28th at the height of the heat wave. The group alleges the mudflow was brought about by melting glaciers in Mauvoisin, Switzerland.

The high pressure system that parked over Europe and brought about the record heat has since moved north, where it’s led to potentially record-breaking melt across Greenland’s ice sheet.

The familiar images of temperature anomalies that are produced by the world’s climate and weather agencies have inspired Philadelphia, Pennsylvania-based artist Diane Burko, who is currently working on a painting depicting the July heatwave in Europe.

An image, provided by artist Diane Burko, shows progress on her painting “European Heat Wave.”

Read More on GlacierHub:

What Moody’s Recent Acquisition Means for Assessing the Costs of the Climate Crisis

Rob Wallace Installed to Post in Department of the Interior

Dispatches from the Cryosphere: Intimate Encounters with the Intricate and Disappearing Ice of Everest Base Camp

Please follow, share and like us:
error

Roundup: World Environment Day, Mount Everest Deaths, and Kangerlussuaq Glacier Retreat

June 5, 2019 is World Environment Day

From GlacierHub writer and environmentalist Tsechu Dolma: “China is hosting World Environment Day 2019, its mounting environmental crisis is endangering hundreds of millions and downstream nations, what happens on the Tibetan plateau has profound consequences on rest of Asia.”

Everest traffic jam blamed for climber deaths

From the New York Times: “Climbers were pushing and shoving to take selfies. The flat part of the summit, which he estimated at about the size of two Ping-Pong tables, was packed with 15 or 20 people. To get up there, he had to wait hours in a line, chest to chest, one puffy jacket after the next, on an icy, rocky ridge with a several-thousand foot drop.

[…]

This has been one of the deadliest climbing seasons on Everest, with at least 11 deaths. And at least some seem to have been avoidable.”

Exceptional retreat of Kangerlussuaq Glacier

From Frontiers of Earth Science: “Kangerlussuaq Glacier is one of Greenland’s largest tidewater outlet glaciers, accounting for approximately 5% of all ice discharge from the Greenland ice sheet. In 2018 the Kangerlussuaq ice front reached its most retreated position since observations began in 1932. We determine the relationship between retreat and: (i) ice velocity; and (ii) surface elevation change, to assess the impact of the retreat on the glacier trunk. Between 2016 and 2018 the glacier retreated ∼5 km and brought the Kangerlussuaq ice front into a major (∼15 km long) overdeepening. Coincident with this retreat, the glacier thinned as a result of near-terminus acceleration in ice flow. The subglacial topography means that 2016–2018 terminus recession is likely to trigger a series of feedbacks between retreat, thinning, and glacier acceleration, leading to a rapid and high-magnitude increase in discharge and sea level rise contribution. Dynamic thinning may continue until the glacier reaches the upward sloping bed ∼10 km inland of its current position. Incorporating these non-linear processes into prognostic models of the ice sheet to 2100 and beyond will be critical for accurate forecasting of the ice sheet’s contribution to sea level rise.”

On April 19, IceBridge’s 23rd flight of the Arctic 2011 campaign surveyed numerous glaciers in southeast Greenland including Kangerlugssuaq Glacier. The calving front of the glacier gives way to ice floating in the fjord, referred to by some as a sikkusak, or mélange. (Source: NASA ICE/Michael Studinger via Flickr)

Read More on GlacierHub:

UNESCO-Recognized Glaciers Could Shrink 60 Percent by End of Century

Scientists Catch Tibetan Snowcocks on Camera in their High-Elevation Habitats

GlacierHub Seeks Contributors for Its New, International Feature Series

Please follow, share and like us:
error

Video of the Week: Flying over Jakobshavn Glacier

In this Video of the Week, watch an aerial view of the flow line at the Jakobshavn Glacier, in Ilulissat, Greenland. The video was posted on Twitter by Santiago de la Peña of Ohio State University’s Byrd Polar and Climate Research Center.

“This behemoth shreds into the ocean the equivalent of San Francisco’s water consumption,” he said.

Jakobshavn glacier is well known for likely producing the iceberg that sunk the Titanic.

It is also a very dynamic glacier. In the early 2000s, Jakobshavn was one of the fastest-flowing glaciers in the world, losing up to 20 meters in height each year. It is estimated that between 2000 and 2010, Jakobshavn alone contributed almost 1 millimeter to global sea level rise. In more recent years, however, Jakobshavn is actually growing again, now gaining about 20 meters in height per year.

Read more on GlacierHub:

Glaciers Account for More Sea Level Rise Than Previously Thought

Mercury from Melting Glaciers Threatens the Tibetan Plateau

Nepal Considers Uranium Mining Proposal in the Himalayas

Please follow, share and like us:
error

Video of the Week: A ‘Staggering’ Amount of Meltwater in Greenland

Researcher Santiago de la Peña of Ohio State University’s Byrd Polar and Climate Research Center posted video on Twitter of raging streams of meltwater carving through the surface of Greenland’s Russell Glacier.

“Early May and melt season is already in full swing in western Greenland,” he wrote. “The amount of meltwater at Russell glacier for this time of year is staggering.”

The glacier is located on the west coast of Greenland.

Peña studies ice sheet dynamics and surface mass balance in Greenland and Antarctica.

In several tweets following his video of Russell Glacier, Peña described high temperatures and large amounts of meltwater.

“We serviced 2 stations at an elevation of 2300m and 1900m; the lower site was above freezing, the other at -4C. They are usually in the -20s and -30s this time of the year,” he wrote in a May 6 tweet.

A study published last month in the journal Nature found that glacier melt is occurring more rapidly than previously thought and accounts for 25-30 percent of observed sea level rise since 1961.

Read More on GlacierHub:

Glaciers Account for More Sea Level Rise Than Previously Thought

Illustrating the Adventures of German Naturalist Alexander von Humboldt

Video of the Week: Can Blankets Protect Swiss Glaciers from Melting?

Please follow, share and like us:
error

Roundup: Catastrophe on Mt. Ararat, Albedo Effect in the Alps, and Meltwater in Greenland

Reappraising the 1840 Ahora Gorge Catastrophe

Mt. Ararat is seen from the northeast in 2009. (Source: Wikimedia Commons)

From Geomorphology: “Ahora Gorge is a 400 m deep canyon located along the North Eastern flank of Mt. Ararat (Turkey), a compound volcanic complex covered by an ice cap. In the past, several diarists and scientific authors reported a calamitous event on July 2, 1840, when a landslide triggered by a volcanic eruption and/or an earthquake obliterated several villages located at the foot of the volcano. The reasons and effects of this Ahora Gorge Catastrophe (AGC) event have been obscure and ambiguous. To reappraise the 1840 catastrophe and the geomorphic evolution of the Ahora Gorge, we used high-resolution satellite images, remote sensing thermal data supplemented by observations collected during two field surveys.”

Albedo Effect in the Swiss Alps

The Oberaar glacier is seen from Oberaar, Bern, Switzerland in 2010. (Source: Simo Räsänen/Wikimedia Commons)

From The Cryosphere: “Albedo feedback is an important driver of glacier melt over bare-ice surfaces. Light-absorbing impurities strongly enhance glacier melt rates but their abundance, composition and variations in space and time are subject to considerable uncertainties and ongoing scientific debates. In this study, we assess the temporal evolution of shortwave broadband albedo derived from 15 end-of-summer Landsat scenes for the bare-ice areas of 39 large glaciers in the western and southern Swiss Alps. […] Although a darkening of glacier ice was found to be present over only a limited region, we emphasize that due to the recent and projected growth of bare-ice areas and prolongation of the ablation season in the region, the albedo feedback will considerably enhance the rate of glacier mass loss in the Swiss Alps in the near future.”

Glacier Meltwater Impacts in Greenland

An iceberg floats in Franz Josef Fjord, Greenland (Source: Wikimedia Commons)

From Marine Ecology Progress Series: “Arctic benthic ecosystems are expected to experience strong modifications in the dynamics of primary producers and/or benthic-pelagic coupling under climate change. However, lack of knowledge about the influence of physical constraints (e.g. ice-melting associated gradients) on organic matter sources, quality, and transfers in systems such as fjords can impede predictions of the evolution of benthic-pelagic coupling in response to global warming. Here, sources and quality of particulate organic matter (POM) and sedimentary organic matter (SOM) were characterized along an inner-outer gradient in a High Arctic fjord (Young Sound, NE Greenland) exposed to extreme seasonal and physical constraints (ice-melting associated gradients). The influence of the seasonal variability of food sources on 2 dominant filter-feeding bivalves (Astarte moerchi and Mya truncata) was also investigated. Results revealed the critical impact of long sea ice/snow cover conditions prevailing in Young Sound corresponding to a period of extremely poor and degraded POM and SOM.”

Read More on GlacierHub: 

Rising Temperatures Threaten Biodiversity Along the Antarctic Peninsula

Mongolia’s Cashmere Goats Graze a Precarious Steppe

United Nations Steps for Building Functional Early Warning Systems

Please follow, share and like us:
error

Video of the Week: Massive Calving Event at Helheim Glacier

In this week’s Video of the Week, watch a massive glacier calving event that occurred at Helheim Glacier in Greenland. The video was captured on 22 June 2018 by Denise Holland of New York University.

The calving event took place over a 30-minute time period, and was sped up into a time-lapse of about 90 seconds. During this time span, over four miles of the glacier’s edge broke off, flowing into one of the fjords that connects Helheim Glacier to the ocean. To put this in perspective, a calving event of this size would measure roughly the size of lower Manhattan, all the way to Midtown in New York City. In a warming world, glacier calving is a large force contributing to global sea-level rise.

Discover more news on GlacierHub:

Glaciers and Reefs with Diane Burko

Ice Loss, Gravity, and Asian Glacier Slowdown

Historical Data on Black Carbon and Melting Glaciers in Tibet

Please follow, share and like us:
error

Epidemics and Population Decline in Greenland’s Inuit Community

The dynamics of climate and environment have a large and growing influence on our culture, practices and health. Climate change is expected to impact communities all over the world, requiring people to adapt to these changes. A recent study by Kirsten Hastrup in the journal Cross-Cultural Research looks at the history of health and environment of the Inuit people of Greenland’s Thule community. Global warming has impacted the hunting economy in the region, and increasing sea contamination is negatively affecting the Arctic ecosystems and human health. Kirsten Hastrup locates these recent changes in the context of earlier dynamics, identifying the social and environmental factors contributing to Inuit development over time.

Effects of Early Exploration and Trade

Colorful houses in the Thule community (Source: Andy Wolff/Flickr).

The Thule community is located in the far northern region of Qaanaaq, Greenland. It is called Avanersuaq, or “Big North,” in the Inuit language of Iñupiat. The Little Ice Age, which lasted from the 14th to 18th century, isolated this small population of 140 from other communities and regions in the south. Waters opened with melting sea-ice in the 19th century, allowing European explorers and whalers to contact the region and the Inuit people. The explorers engaged in trade with the Inuit, exchanging wood, guns, and utensils for fur. Unfortunately, trade and the arrival of whalers introduced new diseases to the community, leading to epidemics and population decline.

Hastrup explains that the Inuit also suffered from famine at the time due to the grip of the Little Ice Age. Expansion of inland ice and glaciers and persistent sea ice made it hard for the Inuit to hunt for food sources like whales, walruses and seals. A lack of driftwood used to make bows, sleds and build kayaks for hunting also contributed to the Inuit’s hardship and further population decline. Natural hazards from living in the Arctic environment led to the decline on a smaller scale. Some of these deaths were due to instabilities of the icy landscape, accidents while traveling across expanses of ice, and large animal attacks during hunting.

Cold War Implications on Health and Identity

Although the risk of disease was great, Hastrup recognizes the impacts of diseases. She also identifies the benefits of trade, which brought resources necessary for hunting and overcoming famine. Development of formal trading stations and greater access to wood allowed for increased hunting capability. Fur trade became quite profitable for the Inuit toward the early 20th century, much to the benefit of the local economy.

However, this did not last long, according to Hastrup. During the Cold War period, the Arctic became a sort of frontier between the U.S. and the Soviet Union. An American airbase was established in the early 1950s, and this had long-lasting effects on health and Inuit identity. Transport vessels, airplanes, and heavy activity at the airbase disturbed the Arctic animals, damaging important Inuit hunting grounds. The population had to relocate to make room for the airbase. This forced movement to new housing sites left a sense of dislocation among the Inuit community.

Fighter aircraft at the Thule Air Base,1955 (Source: United States Air Force/Creative Commons).

A new health risk was introduced in 1959 with the launch of Camp Century, a scientific military camp built under the ice cap. This nuclear-powered camp was also secretly designed to house missiles during the Cold War. The movement of the ice sheet led to an abandonment of the camp in 1966; however, the nuclear threat continued. In 1968, a plane carrying plutonium bombs crashed, going right through the sea ice outside of Thule. Three bombs were retrieved from the waters, although reports in European news media suggest a fourth bomb remains. A nearby fjord was also later revealed to be contaminated by nuclear radiation. According to Hastrup, the people in the region continue to fear risks from radiation-related illness and contaminated food.

Impacts of Changing Climate

These activities and the historical implications of outside contact have left a deep-rooted concern for health and well-being among the Thule community, one that is felt even today. According to Hastrup, many fear that changes in the environment may expose them to further ice-trapped radiation. Camp Century was eventually buried within a glacier, and continued warming is causing movement within the ice. Some Inuit worry that leftover radiation might be released if the glaciers were to retreat, harming the health of their community, Hastrup reports.

Seal meat drying on a platform safe from sled dogs. Qaanaaq, 1998 (Source: Judith Slein/Flickr).

Warming trends impacting the Arctic regions are influencing Inuit practices in certain ways. No longer able to subsist as hunters, for example, the Inuit have adapted to halibut fishing for income. Hastrup argues that in its own way, this adaptation adds a sense of dislocation from tradition. Sharing of game was a longtime tradition among the community, which provided a feeling of unity.

Sherilee L. Harper, associate professor at the Public Health School of the University of Alberta, told GlacierHub about how changing climate might continue to affect the Inuit community. “Research, based on both Inuit knowledge and health sciences, has documented impacts ranging from waterborne and foodborne disease to food security to unintentional injury and death to mental health and wellbeing,” she said.

Despite shifts in traditional practices, Inuit appear ready to meet the challenges of their changing environment. As oceans continue to warm and threaten this Arctic ecosystem, Inuit residents continue to work with governments and climate scientists to monitor changes, deploy conservation efforts, and manage local development. Their openness to change is shown in their shifts to commercial fur collecting in the past to new forms of fishing in the present. Harper added that the Inuit have shown resilience to climate change and continue to be international leaders in climate change adaptation.

Please follow, share and like us:
error

Massive Impact Crater Discovered Beneath Greenland Glacier

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.

An aerial view zooms into a sub-ice crater perspective with overlays of Washington, DC and Paris for relative size (Source: Cindy Starr/NASA Scientific Visualization Studio).

A Huge Crater and a Hunch

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.

Agpalilik, a fragment of a larger Greenland meteor, outside the Geological Museum in Copenhagen (Source: Mads Bødker/Flickr).

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.

 

Cross-section of the impact crater. The bottom layers of disturbed Pleistocene ice are apparent (Source: Cindy Starr/NASA Scientific Visualization Studio).

 

Could the Impact Have Triggered Sudden Climate Change?

The cold-loving Dryas flower (Source: Jörg Hempel).

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.

Broecker Unconvinced Impact Triggered Younger Dryas

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.

The Hiawatha impact crater is plainly visible at the top of the image (Source: NASA/John Sonntag).

 

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.

 

“Once you start looking for structures beneath the ice that look like an impact crater, Hiawatha sticks out like a sore thumb,” MacGregor told the New York Times (Source: Cindy Starr/NASA Scientific Visualization Studio).

 

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.

 

Please follow, share and like us:
error

Roundup: Citizens Tracking Glaciers, Seismic Noise, and Holocene Glaciers

Park Enlists Citizens to Track Changes in Teton Glaciers

From U.S. News: “The project aligns with one of Grand Teton’s fundamental duties, keeping tabs on its natural resources. Estimates vary, but with global temperatures increasing some studies suggest many glaciers could disappear within the next few decades.”

Read more about Citizens Tracking Glaciers here.

Grand Tetons (Source: Brian Perkes/Flickr).

 

Fracturing Glacier Revealed by Ambient Seismic Noise

From AGU 100: “Here we installed a seismic network at a series of challenging high‐altitude sites on a glacier in Nepal. Our results show that the diurnal air temperature modulates the glacial seismic noise. The exposed surface of the glacier experiences thermal contraction when the glacier cools, whereas the areas that are insulated with thick debris do not suffer such thermal stress.”

Read more about glaciers and seismic noise here.

Annapurna, Nepal (Source: David Min/Flickr).

 

Holocene Mountain Glacier History in Greenland

From Science Direct: “Here, we use a multi-proxy approach that combines proglacial lake sediment analysis, cosmogenic nuclide surface-exposure dating (in situ10Be and 14C), and radiocarbon dating of recently ice-entombed moss to generate a centennial-scale record of Holocene GIC fluctuations in southwestern Greenland.”

Read more about holocene mountain glacier history here.

Qoroq Ice Fjord, Narsarsuaq (Source: Alison/Flickr).

 

 

Please follow, share and like us:
error

Are Melting Glaciers Putting Arctic Fish at Risk?

Shifts in Capelin Fish Feeding Ecology

An important Arctic fish might be in trouble. A recent study in Greenland examines changes in the feeding ecology of capelin, a small forage fish in the smelt family. Melting glaciers are affecting its diet, and this change in diet can heavily influence its growth and reproduction. This could spell trouble for the other animals that eat capelin.

Found in the Arctic, Capelin are an important food source for marine mammals such as whales and seals. Atlantic cod, a major commercial fish species, are one of its major predators. Atlantic puffin also like to feed on them, along with other sea birds.

A puffin enjoying a mouthful of what appears to be capelin (Source: Lawrence OP/Flickr).

Capelin enjoy feeding on plankton, microorganisms that float in the sea and on freshwater. Krill, small shrimp-like crustacean, are also crucial in the diet. Capelin seem to migrate less than other species, making them extremely dependent on the food that’s readily available to them. Any major changes in food availability can ripple through the Arctic food web.

The Godthåbsfjord in West Greenland was sampled at a number of sites, all the way from the mouth where it opens to the ocean to the furthest inland basin. Capelin were sampled by the researchers during the months of May and August, when increased meltwater from summer heating flows into the fjord. The fish were then divided into 2-cm interval size groups, assessing for differences in age. Researchers carefully dissected the stomachs and intestines, preserving them so that they could later examine their contents to determine diets over different locations and times.

Lorenz Meire talks about the framework of the study in an interview with GlacierHub. Meire is a marine scientist at the Royal Netherlands Institute for Science Research and one of the scientists behind this study. “By trawling in a sub-Arctic fjord impacted by glacial meltwater, we aimed to assess the change in capelin size distribution and its diet throughout the season,” he says. Meire adds that scientists tried to link diet with observed changes in zooplankton biomass and environmental conditions.

Three small capelin on tin foil (Source: Rodrigo Sala/Flickr).

What are some observed environmental changes?

Studies show a shift in abundance of krill from freshwater-influenced regions toward the oceans. We see similar shifts with large plankton. GlacierHub spoke with Kristine Engel Arendt, a marine biologist from the University of Copenhagen. Her research on plankton community structure is referenced in the study. She provides some insight on how runoff from the exit glacier and high up ice sheets affect the ecosystem ecology, looking particularly at smaller plankton species.

Arendt told GlacierHub that the fjord typically experiences a bloom of algae in the spring, which is a food source for plankton. The addition of freshwater from the late summer runoff initiates a second bloom of algae, driven by an upwelling of nutrients. “The marine food web is closely linked to the energy source from the algae bloom, and therefore zooplankton species that can utilize food over the entire summer period are favored,” she says. These smaller species of plankton benefit from the nutrients. They use this extra algae bloom during the summer to grow and reproduce. This observation indicates an abundance of smaller plankton at the inner basin region in August. Stomach examinations show a clear increase of small plankton in the diet of fish from this area of the fjord.

Drifting Ice, Godthåbsfjord, West Greenland (Source: Lorenz Meire).

Arendt points out that climate change effects such as melting glaciers are not always negative. We see that this inflow of freshwater is in fact beneficial to these smaller plankton. But how might this change affect capelin?

A Disadvantage to Younger Capelin

It’s important to look at the migration and reproductive pattern of capelin to understand the impacts. Maturing adult capelin spawn from April to June in the fjord, from the inner basin to near-coastal regions. Studies show that all male capelin and some females die off with connection to spawning. Researchers can then presume that the May sample will consist of both mature and immature capelin, and August will be dominated by young capelin. This is reflected in the findings of the study.

The beautiful fjords of Greenland (Source: GlacierHub author Arley Titzler)

The quality of the available food sources must also be examined. It differs with plankton size. Larger plankton species are relatively richer in fat per unit of weight. This makes them more ideal for energy intake and growth than the smaller plankton species. Energy intake and growth is particularly critical for young capelin. Meire told GlacierHub, “If smaller copepods (plankton) become more abundant, they will form a more important food source for capelin. Though this can impact the energy transfer as small copepods in the diet cannot compensate for the absence of larger copepods and krill.”

Lack of the more favored species in the inner regions can negatively affect nutrition of capelin. Younger capelin here are at risk. They will need to feed on the larger, fat-rich plankton to receive enough nutrients to effectively grow and reproduce. This can greatly affect the Arctic food web.

Please follow, share and like us:
error

Video of the Week: Rising Waters, Rising Poets

In this week’s Video of the Week, watch two poets from two different walks of life unite to call attention to climate change. Aka Niavana is from Greenland, and she reflects on the way life is changing as the glaciers around her melt. Kathy Jetnil-Kijner is from the Marshall Islands, where her home is threatened by the melting ice and rising seas. In a joint expedition to the remote fjords of southern Greenland, the two activists perform their poetry, hoping to inspire action on climate change.

The story, published in The Guardian, is written by Bill McKibben, co-founder of 350.org.


Read more glacier news here:

New Study Highlights Loss & Damage in Mountain Cryosphere

India’s Glaciers Help Shape Climate Change Policy

Seeing is Believing: Project Pressure’s Cryosphere Exhibition at Unseen Amsterdam

Please follow, share and like us:
error