Millennial Climate Effects on a Lake Ecosystem in Southern Chile

With climate change, people are eager to understand environmental changes over the last few millennia. Unfortunately, regions in the Southern hemisphere are not as well understood as those in the Northern hemisphere, where more data sources are found. This information can be useful in estimating future environmental changes.

A recent study published in the journal The Holocene, scientists examine the millennial changes in the environmental conditions in the Lake Pastahué ecosystem of Chiloé Island, located in southern Chile. Two particular climate events within this period are compared: the Medieval Climate Anomaly (MCA), which was a period of warming from 800 and 1300, and the Little Ice Age (LIA), when temperatures dropped between 1300 and 1850. Scientists investigated signals of climate change in history through analyzing sediment samples from the lake. They also examined historical records to help reconstruct past environmental conditions.

Houses on stilts line the edge of Chiloé Island (Source: Backpackerin/Pixabay)

Biological indicators (pollen and midges) and sedimentological indicators (organic matter and magnetic susceptibility) provided information on the past ecology. Tiny pollen particles that slowly settle into the earth signify historic plant and forest compositions. Midges, popular for fly-fishing, were used as indicators of the trophic changes in lake. Sedimentological indicators allowed researchers to establish a chronological timeline of the core sample, and provided useful information on soil quality.

Researchers found that the highest percentage of pollen was observed during the MCA period. The particles came from trees typically found in the temperate Valdivian forests, suggesting warm conditions. An absence of aquatic plant species, along with an increase in plant species suggests decreased precipitation and increased temperature. Midges adapted to warm conditions were found in this sample, as well as species adapted to semi-terrestrial ecosystems. This suggests the lake was impacted by surrounding terrestrial ecosystem, or a lower water level. These findings were then compared to historical records from 1100-1350, where similar conditions were also observed in Central Chile.

For the LIA period, records show that the climate in central Chile was cooler and more humid beginning in 1350. Pollen results match those of cold events from the Northern Hemisphere. Pollen from trees and shrubs found typically in the North Patagonian forest were recovered, reflecting cold and humid conditions. Aquatic species are much more abundant in this sample, suggesting a larger lake basin. The vegetation structure was also noted to evidence a more humid environment than the earlier period.

Patagonia stretches around 260,000 square miles across South America, consisting of glaciers, steppes, and forests. (Source: Max Pixel)

Historical records of San Rafael Glacier give us a glimpse into the past environment of the region. On a journey from Chiloé to San Rafael Glacier in 1766, a priest described ice floating along the coast up to the glacier. At a later period, Captain Enrique Simpson, a military officer and Admiral of the Chilean Navy, referenced the dimensions of the glacier during his explorations of Chilean archipelagoes in 1875. He reveled at the size of the glacier, describing it as more than a thousand meters high and extending many miles from north to south. According to the article, an explorer at a later period, Hans Steffen in 1910, shared similar findings. “Studying the location and the current dimensions of this huge glacier, we found almost no difference with description given by Captain Simpson on his voyages,” said Steffen.

GlacierHub spoke with Michael Kaplan, a glaciologist who studies climate history in South America. Kaplan considered it novel that the researchers used many techniques and examined historical records in the article. He found it useful to include the historical records of the extensiveness of glaciers, especially considering the state of glaciers in South America today. This reference helps show how climate changes have impacted glaciers and influenced retreat over the course of the millenium. Kaplan also felt that researchers have effectively represented environmental changes in this region during the MCA and LIA. “They show that these events had some manifestation in southern South America, and that’s a really important finding of the paper,” he added.

San Rafael is a major outlet glacier of the Northern Patagonia Ice Field in southern Chile. (Source: Mujer Chilena/Flickr)

Scientists from the study have also observed a growing reduction in tree pollen for the last century. They found that most midge species have diminished. The absence of species related to high nutrient levels suggests that the nutrient conditions at the lake were lower than previous periods. Conditions at this time were warmer and drier than the LIA, and this supports tree ring data which presents the previous 100 years as some of the driest in recent centuries. These environmental changes can be expected to intensify if the climate continues to experience dry conditions.

Marcos Mendoza, an anthropologist who studies environment in Latin America, commented on the relevance of this information for climate projections. Mendoza also told us that these types of studies can be useful in understanding how tree and plant species might respond to future climatological changes. “As indigenous communities, scientists, land managers, and others begin to anticipate how changing temperatures and precipitation patterns will affect the Latin American region of Patagonia, studies like Castro et al. provide windows onto past environmental and climatological conditions,” he said.

This study is useful in understanding the sensitivity of environmental systems to changes in climate. Although historical require careful digging through sources, they can be useful in filling in the gaps in our understanding of past environmental conditions. Reconstructing past conditions can help assess potential changes as well, which may impact people and their environments.

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.

A Classic Whodunit: Industrial Soot, Volcanoes, and Europe’s Shrinking Glaciers

In the second half of the 1800s, glaciers in the Alps rapidly shrunk in length, some by hundreds of meters. Their alarming retreat, documented in photographs, has often been a symbol of the human influence on global climate, as the accelerated melting aligned with increased production of industrial soot. But were there other factors that drove the rapid glacier recession in the Alps at the end of the Little Ice Age?

Surface darkening from mineral dust and soot deposited on the Aletsch glacier. The Colle Gnifetti drilling site lies in the background (Source: Michael Sigl).

A new study in The Cryosphere led by Michael Sigl, a chemist and climatologist at the Paul Scherrer Institute (PSI) in Switzerland, challenges the notion that human-made industrial soot, or more formally black carbon, from European industrialization was primarily responsible for the observed deglaciation during the 15-year period between 1860 and 1875.

Based on their comparison of high-resolution black carbon deposition records from ice cores from the Colle Gnifetti glacier in the Swiss Alps and historical data of the changing lengths of major Alpine glaciers, the researchers discovered that “when black carbon concentrations started to significantly rise (around 1875), Alpine glaciers had already experienced 80 percent of their 19th century retreat, meaning that black carbon was not the first responsible for this retreat, contrary to what was suggested in a previous study,” team member Dimitri Osmont, a doctoral student at the PSI, told GlacierHub, referring to earlier research published in the Proceedings of the National Academy of Sciences of the United States of America.

“Of course, this doesn’t mean that black carbon didn’t contribute at all (especially during the 20th century when concentrations are significantly higher, and also today in the case of Himalayan glaciers), but it was not the first driver,” Osmont told GlacierHub.

Sigl further elaborated on the discrepancies between his team’s findings and that of previous research in discussion with GlacierHub. “If the glaciers had actually been forced to retreat by more abundant soot impurities in the snow, one would expect the glaciers’ retreat to have been synchronous with or slightly lagging increases in black carbon deposition. But we observe the exact opposite and conclude that other factors, predominantly volcanism, account for most of past glacier variability,” he said.

The TUNU ice-core in Greenland containing a continuous archive of global volcanism (Source: Michael Sigl).

Volcanoes? Indeed, a series of massive volcanic eruptions in the early 1800s, like the catastrophic Mount Tambora in 1815 behind Europe’s Year Without a Summer, resulted in a few decades of cooler and wetter conditions conducive for the Alpine glaciers to surge and grow. Not to belittle the sheer devastation experienced locally and the socioeconomic effects of altered agricultural patterns across the globe, other positive takeaways of the eruptions included artistic inspiration for vibrant sunsets in J. M. W. Turner paintings, the backdrop of Mary Shelley’s Frankenstein, and the peak of larger glaciers in the Alps to phenomenal lengths in the middle of the 1850s.

The team argues that this more favorable atmosphere for the glaciers allowed them to grow to their peak size in the 1850s and that the rapid retreat from 1860 to 1875 was the glaciers simply returning to their “normal” size. They conclude that whatever role anthropogenic black carbon had in Alpine glacier retreat before 1875 was negligible in comparison to the natural decadal factors.

But other scientists disagree with their findings, including Thomas Painter, the author of the study whose hypothesis was tested and a principal scientist at NASA’s Jet Propulsion Laboratory in California. “Sigl et al. performed admirable work with their ice core analysis, and it is alone an important contribution to understanding deposition dynamics of atmospheric constituents,” Painter told GlacierHub. However, he found that the study “attacked a strawman argument that the glacier retreat in the 19th century predated the emergence of black carbon deposition and its additional absorption of sunlight in the snowpack.” He challenges this new study’s claims that they disprove his hypothesis. “The glaciers did start retreating from a cold period, but they then kept on strongly retreating to lengths not seen in the previous centuries, while air temperature and precipitation didn’t change sufficiently to cause this,” he said.

Image of the Colle Gnifetti glacier in 2015. It’s the ice-core drill site hosting a continuous archive of air pollution since 1741 A.D. (Source: Michael Sigl).

Regardless of the differing conclusions, none of the scientists from the recent study contacted by GlacierHub discounted the role of human activity on glacier retreat. “Just to be very clear, the study in no way neglects the generally significant contribution of anthropogenic emissions to the ongoing observed worldwide glacier retreat, but black carbon, at least for the alpine region, was not a major factor for the 19th century retreat,” stated Theo Jenk, another co-author of the study from PSI. Painter and Jenk’s colleagues are sure to butt heads further, but all in the name of sound scientific endeavor.

Tracing the Glaciation of the Greater Caucasus Mountains

In a paper published last month in the Open Journal of Geology, four researchers from the Ivane Javakhishvili Tbilisi State University of Georgia traced the old glaciation of the Caucasus Mountains from the 17th to 19th century during the Little Ice Age. These mountains are the highest mountains in Europe. Despite being remote, studying their processes can aid in the understanding of global climate history.

In this study, it is remarkable that the team had a robust methodology comprising a rigorous review of local knowledge and sources from the indigenous people as well as the analysis of rock samples collected during their expeditions. Reading a collection of folklore from the mountain communities by A. Krasnov, the team was able to reconstruct the advance of local glaciers that stretched all the way down to the populated mountain valleys during that epoch. This collection served as a first-hand account on the extent of glaciation based on the location of the villages.

Map of Caucasus Mountain Range
Map of Caucasus Mountain Range (Source: Wikimedia Commons).

Divided into the Greater Caucasus in the North and the Lesser Caucasus in the south, the Caucasus mountain region in West Asia stretches between the Black Sea and Caspian Sea. It is formed from the tectonic plate collision between the Arabian and European plates, occupying territory in Georgia, Armenian, Azerbaijani, Russia, Turkey and Persia. According to a local Georgian Svanetian poem by Nizardze, glacier advances had reached a distance of up to 17km during the peak of the Little Ice Age.

The existence of Russian topographic maps from the second half of the 19th century also helped form a broad picture of the latest glaciation. This knowledge was then further corroborated with other sample data collected in the team’s expedition.

The first technique used was petrography, which is the classification of rocks based on physical structure and mineral content. Present-day block debris from moraines could be reconstructed with this information to find out their main centers and from thereon, historical glacier movement and distribution boundaries.

The second technique used was palynology, which is the study of microscopic matter. It was used to identify the genesis of loose sediments from moraines. Using 590 pollen samples, the fossilized plant spectrum in the loose sediments were analyzed to explore if weathering of the moraines occurred as a result of glaciation or fluvial action and the time periods they occurred in. Information about whether the rocks were covered in ice at that point in time would allow researchers to estimate the extent of glaciation.

The summit of El Ushba, a peak in the Georgian Caucasus Mountain Region
The summit of El Ushba, a peak in the Georgian Caucasus Mountain Region (Source: Inakimiro/ Instagram).

“The glaciers completely filled the river valleys of the Greater Caucasus, passed the foothills and covered some of the piedmont valleys. It is supposed that the strongest glaciation took place in the Terek (the northern slope) and Kodori (the southern slope of the Greater Caucasus) river basins as well as in the Enguri and Rioni basins,” the research notes.

Until today, the actual mudflow activity in the Caucasus is still rather intensive (especially in the east). However, it appears that in the past it was even more intensive due to the tectonic shoves, rock falls and catastrophic thaw of large glaciers during highly dynamic glacial epoch. Based on the traces of glaciers, the Caucasus ancient snow-line is still about 700 to 1000 meters lower than the contemporary one.

Research suggests that the minor glacial epoch experienced by the Caucasus Mountains was intensified by the South European covering glaciation. However, the team believes that atmospheric circulation processes and regional tectonic movements are the main drivers of the glaciation.

The Little Ice Age remains the heart of geological research in the Caucasus Mountains since it is the last stage of glacial advance in the region. Hence, the geological mystery on the relative importance of the drivers for minor glacial epoch is still being debated.

 

Photo Friday: Jostedalsbreen Glacier

Jostedalsbreen Glacier, the largest glacier in northern Europe, is located within Jostedalsbreen National Park which was founded in 1991 in Norway. The Jostedalsbreen Glacier is so large that it alone covers over a third of the park and separates two of the longest fjords in the world. It is fitting that Norway has such an imposing glacier since the most iconic Norwegian characteristics—fjords and valleys—owe their creation to past glacial movements.

Scientists have flocked to this glacier for centuries to study its retreat since the Little Ice Age, particularly with an interest in studying post-glacial vegetation and landscape. As climate change accelerates glacial retreat across the world, a degree of urgency is added to the quest to learn from Jostedalsbreen Glacier’s retreat. Sometimes, the past can help us prepare for the future.

 

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Glaciers Provide Insight on Norse Migration

Recent research on the dynamics of glaciers in the Arctic over the last millennium has altered understandings of climate history and of human migrations in this inhospitable region. Glaciers in Baffin Island and western Greenland reached their maximum extent during the time of Medieval Warm Period,  roughly 950-1250,  instead of the Little Ice Age of the sixteenth through nineteenth centuries,  according to a recent research paper published in ScienceAdvances. This and other paleoclimate data suggest that the western North Atlantic region remained cool during the Medieval Warm Period, while the eastern North Atlantic was comparably warmer. Understanding these climate patterns provides insight into the migration patterns of the Norse from Scandinavia into the Arctic during the Medieval Warm Period.

Glaciers and Little Ice Age moraines in western Greenland. Credit: Jason Briner
Glaciers and Little Ice Age moraines in western Greenland. (credit: Jason Briner/popular-archaeology)

Glaciers are sensitive to variations in temperature and precipitation, so historical data on glacier fluctuations  can allow researchers to reconstruct past climates.  For example, if a glacier advances over an area with trees, the trees—and therefore the glacier advance—can be reconstructed through radiocarbon dating.  However, Arctic glaciers did not overrun trees, so it is difficult use this method to draw the true picture of glaciers during the late Holocene, covering the last 4000 years. Instead, researchers examine moraines, the rocks deposited at the front and sides of glaciers as they advance, or when they remain stable for some period.  When a rock is added to a moraine, it is exposed to cosmic rays, which slowly change the isotopes of certain elements within it. By examining the ratio of isotopes, scientists can determine the time since the rock was added. In this way, they determine the age of the moraine and reconstruct the history of glacier movements. This research allows them to reconstruct past climates. This information complements the records of past climate in ice cores and marine sediments, which till now have been the principal data sources which are used to establish the climate history of the Arctic.

Sampling a moraine boulder for beryllium-10 surface exposure dating. Credit: Nicolás Young. From popular-archaeology
Sampling a moraine boulder for beryllium-10 surface exposure dating. (credit: Nicolás Young/popular-archaeology)

Nicolás E. Young and his colleagues  used a cosmogenic isotope, beryllium-10,  to study the development of moraines over the last millennium, focusing on  Naqsaq in Greenland and Ayr Lake in Baffin Island. They report that the size of glaciers in Baffin Island and western Greenland during the Medieval Warm Period was similar to their size during the Little Ice Age, so temperatures in this area during the Medieval Warm Period were cooler than was believed, despite the period’s name. These findings are of particular interest, because they provide clues for understanding human migrations at the time.

Moving westward from their homelands in Scandinavia, the Norse settled in Iceland in the 9th century and arrived in Greenland in the 10th century.  Researchers had previously believed that the Norse were attracted by green lands and a relatively mild climate during Medieval Warm Period. They argued that temperatures at the time were  approximately 1º C higher than at the present and the associated decrease in sea ice in the North Atlantic allowed the Norse to travel to areas they had not been able to reach before.

Vikings Boat, by poweredbyosteons
Reconstruction of a Viking boat (credit: poweredbyosteons)

However, the new research  indicates that the climate during the Medieval Warm Period in the North Atlantic, when Norse made their settlements in Iceland and Greenland, was similar to the Little Ice Age, rather than being warmer. This suggests that the Norse migrations may not be related to climate factors, as previously believed. The authors propose that other socioeconomic factors, including the decline of their trade with other areas, contributed to Norse migrations. The Norse departure from Greenland might reflect their search for trading opportunities rather than to deteriorating climates during the Little Ice Age, though more research is needed to better understand this migration from Greenland at the end of the Medieval Warm Period.

The researchers also note that the climatic factors that contributed to the shift from the Medieval Warm Period to the Little Ice Age in the Arctic region are still under discussion, although the long-term cooling trend in the eastern North Atlantic is considered to be driven by a gradual decrease of solar radiation. Shifts in ocean currents, the effects of volcanic eruptions, and processes within the atmosphere might also be of importance.  As this work advances, we will have a deeper understanding, not only of past climates, but of the history of our own species as well.

Melting Glaciers Give Earth a Pop

Southeast Alaska shown in the red rectangle (Source: Google Earth).
Southeast Alaska shown in the red rectangle (Source: Google Earth).

Though the Earth often seems solid and fixed, it is not. You’ve probably heard of continental drift—the horizontal movement of continent-sized bodies of rock—but fewer of you may appreciate that the earth can move vertically as well. Studies have shown that North America and Europe are rebounding, slowly but steadily, due to the removal of thick ice sheets which once covered them during the last ice age, which ended about 21,000 years ago.

This process of postglacial upward movement is called glacial isostatic adjustment (GIA). Researchers have established that some materials have a viscous response when a surface load is placed on them, flowing like slow-moving honey, and remaining deformed when the load is removed; others have an elastic response, stretching like rubber and bouncing back to their original form. The substances that compose the upper sections of the earth are somewhere between these extremes, and have what is termed a viscoelastic response. As a result, when a mass of an icesheet is removed, the solid Earth underneath may display some degree of rebound. It was observed that the uplift rate in North America and Europe can reach 1 cm/yr.

Researchers have established that the formation of icesheets generated pressure on the underlying rocks, pushing them downward. In addition to this downward dislocation of the crust, the mantle beneath might be compressed as well. Previous studies on GIA have seldom included this compressibility of the Earth in their calculations, because of the complexities and uncertainties that it would introduce into quantitative models. But a paper published by Tanaka et al. earlier this year in the Journal of Geodynamics established a model which includes compressibility for the GIA in southeast Alaska and compared this model to another which did not include compressibility.

Geographic map of southeast Alaska (Source: Carrera et al./USGS).
Geographic map of southeast Alaska (Source: Carrera et al./USGS).

Southeast Alaska, which is also referred to as the Alaska Panhandle, lies west of the Canadian province of British Columbia. This region is known to have the largest GIA rate in North America, approximately 30 mm/yr. The reseachers anticipated that the compressibility effects would be larger and easier to detect in this region. In this region, models of GIA integrate the effect of ice sheet mass variations over three periods: the Last Glacial Maximum (LGM) about 20,000 years ago, the Little Ice Age a few centuries ago (LIA) and present-day (PD).

Measurements of rebound at different locations can serve to test these models, since information is available on the extent of icesheets in different periods. It is known, for example, that icesheets retreated earlier at lower elevations, so effects from earlier periods will be stronger there. In the case of southeast Alaska, rebound results primarily from post-LIA and PD ice melting; the former, larger in magnitude, was incorporated into the compressibility model. This model examined the rheological properties of the Earth’s mantle—the geological processes which allow rocks to flow on long time scales, and a second set of properties, called flexural rigidity, which determine the capacity of the earth’s crust to bend.

Glacier Bay in Southeast Alaska (Source:Kool Cats/flickr).
Glacier Bay in Southeast Alaska (Source:Kool Cats/flickr).

The authors conclude that their modeling efforts demonstrate the value of including compressibility. Without this element, the current uplift rate in southeast Alaska would be 27% (4 mm/yr) slower, and as a result would not match field measurements as well. Phrased in simpler language, they show that the vast ice sheets of the past not only pushed the mantle down, but squeezed it as well. This study demonstrates the great power of ice to alter our planet’s surface, and indicates that it can have measurable effects centuries, or millennia, after it melts.

Glacier Archaeology Comes of Age

The Iceman's reconstruction (c) South Tyrol Museum of Archaeology/A. Ochsenreiter
The Iceman’s reconstruction (c) South Tyrol Museum of Archaeology/A. Ochsenreiter

Have you heard of Ötzi? One of the world’s best-preserved mummies, he immediately became an archaeological sensation when he came to light in 1991, and new details of his story have been surfacing in scientific journals, magazines, television programs and on the radio ever since—Radiolab dedicated an entire episode to Ötzi just last year.

A 45-year-old Neolithic man, fully clothed and carrying a backpack, an axe, a dagger, medicinal plants, and many other personal belongings, he was discovered by a pair of hikers in the Ötzal Alps of Italy lying face down in glacial ice and meltwater. At first the hikers thought he was the victim of a recent mountaineering accident. But when scientists took a look, they discovered the body was over 5,000 years old.

Ötzi could be considered the poster child for what has since become its own branch of study: glacier archaeology.

Ötzi the Iceman, a well-preserved natural mummy of a Chalcolithic (Copper Age) man from about 3300 BC, who was found in 1991 in the Schnalstal glacier in the Ötztal Alps, near Hauslabjoch on the border between Austria and Italy. (South Tyrol Museum of Archaeology)
Ötzi the Iceman, a well-preserved natural mummy of a Chalcolithic (Copper Age) man from about 3300 BC, who was found in 1991 in the Schnalstal glacier in the Ötztal Alps, near Hauslabjoch on the border between Austria and Italy. (South Tyrol Museum of Archaeology)

Though it has been over two decades since Ötzi was discovered, and many more major finds have surfaced in melting ice and snow in the time since then, glacier archaeology is a field that is only now coming into its own. While one-offs like Ötzi and other mummies have made thrilling finds, the potential for recovery of new artifacts is growing as glacial melt accelerates around the globe. Just this November, the first journal dedicated exclusively to glacier archaeology launched: it’s called, suitably, The Journal of Glacier Archaeology.

“There is immediacy to this research,” write the editors in an introduction to the journal’s first annual issue. “Climate models suggest that in the next decades many sites will be lost to melting and decay. Consequently, it is imperative to extend the geographic scope of this research now.” Once the artifacts thaw, they begin to decompose, and shrivel up, which makes them less valuable to researchers, which has lent the hunt for finds a sense of urgency. Vast regions of Asia, Europe, and North and South American have so far been virtually untouched by the discipline. Identifying good new sites in remote glaciated regions of the world is increasingly being done with the aid of advanced technology: not just aerial photography and helicopter surveys, but satellite imagery and geographic systems modeling.

Overview of snow patches sites with archaeological finds in central Norway. Callanan et al, 2014, Journal of Glacier Archaeology, Vol. 1. Norwegian University of Science and Technology.
Overview of snow patches sites with archaeological finds in central Norway. Callanan et al, 2014, Journal of Glacier Archaeology, Vol. 1. Norwegian University of Science and Technology.

The first issue of the journal offers, among other things, an overview of findings about the impeccably preserved 500-year-old “Inca Ice Maiden” and two other mummified Inca children, discovered together in 1999 on Mount Lullaillaco in northwestern Argentina and understood to be human sacrifices; a pollen analysis of caribou dung found on ice patches in the Yukon; a discussion of bronze age arrows found in Norwegian alpine snow patches (see below); and an analysis of GIS (Geographic Information Systems mapping) methods used by glacial archaeologists.

Arrows with shell points recovered from the Løpesfonna snow patch. (a) T25172; (b) T25684. Photo by Åge Hojem:NTNU-Museum of Natural History and Archaeol- ogy. Layout Martin Callanan. Callanan et al, 2014, Journal of Glacier Archaeology, Vol. 1. Norwegian University of Science and Technology.
Arrows with shell points recovered from the Løpesfonna snow patch. (a) T25172; (b) T25684. Photo by Åge Hojem: NTNU-Museum of Natural History and Archaeology. Layout Martin Callanan. Callanan et al, 2014, Journal of Glacier Archaeology, Vol. 1. Norwegian University of Science and Technology.

A series of annual meetings called “Frozen Pasts,” first launched in Switzerland in 2008, provided the impetus for the new journal, according to Martin Callanan, a glacial archaeologist at Norwegian University of Science and Technology in Trondheim and managing editor of the journal. “It’s a bottom-up thing—people working with the same things, the same complex phenomena, the same findings, all finding each other and saying something is going on here, and it’s global, we need to have regular meetings and a proper publication for ourselves,” he says. “It’s its own special little field…we’ve only started looking.”

The Cryospheric Gallery

The funny thing about the term glacial archaeology is that most artifacts recovered intact from melting snow and ice actually come from what are called snow and ice “patches,” according to Callanan. That’s because snow and ice patches don’t grow and recede the way glaciers do, making them less likely to crush artifacts in their midst to dust over time. There is an ongoing debate over whether these formations are considered “glacial” or not, he says, and in terms of their cryospheric properties, they’re not well understood.

“I think initially people thought you could just transfer glacial theory or dynamics over and that would explain them, but that’s not the case,” says Callanan. “They’re at an elevation far below the [glacier] equilibrium line, seem to be of an age that would indicate they are stable, but at the same time, some of them are surrounded by evidence that there’s been movement in the past, so it’s turned out to be one of the really interesting aspects of this. It’s a new member of the cryospheric gallery.” These ice or snow patches, he says, may have been strictly glacial in formation during the Little Ice Age.

The snow patch at  Løftingsfonnkollen on (a) 14 September 2008. (b) 17 September 2008. (c) 21 August 2010. The find location of the Bronze Age shaft (T24138) is marked. Photo by Geovekst, Statens kartverk, Norkart AS (b) and Martin Callanan (a, c). Callanan et al, 2014, Journal of Glacier Archaeology, Vol. 1. Norwegian University of Science and Technology.
The snow patch at Løftingsfonnkollen on (a) 14 September 2008. (b) 17 September 2008. (c) 21 August 2010. The find location of the Bronze Age shaft (T24138) is marked. Photo by Geovekst, Statens kartverk, Norkart AS (b) and Martin Callanan (a, c). Callanan et al, 2014, Journal of Glacier Archaeology, Vol. 1. Norwegian University of Science and Technology.

There is also an ongoing battle over who is allowed into the club–who can and should call themselves glacial archaeologists. Many more traditional archaeological finds have been dug up out of permafrost—a subterranean layer of earth that is frozen year-round and is typically found at some alpine altitudes and at high latitudes, such as the Arctic and Antarctic regions. “There are wonderful complex finds in the permafrost, but they have a different physical background and regime than ice patches, and there’s all sorts of different sites: grave sites, graveyards, villages, houses. Then it would be a more standard archeological excavation, but the warming thing is what binds them together,” says Callanan.

“So I’m part of the school that says permafrost is in, but we’re still arguing about that.”

For a related story in glacierhub about bodies resurfacing as ice melts, check out this link.