The conversationAug 19, 2021 2:15:37 PM IST

In the high mountain regions of the world, life depends on ice. From the Rockies to the Himalayas, glaciers and other accumulations of snow and ice persist throughout the year. Often found on shaded slopes protected from the sun, these patches of ice turn arid peaks into biological hotspots.

As an archaeologist, I appreciate these patches of snow and ice for the rare glimpse they can provide in time through the fog of Alpine prehistory. When people lose objects in the ice, the slabs of ice act as natural freezers. For thousands of years, they can store snapshots of the culture, daily life, technology, and behavior of the people who created these artifacts.

Frozen heritage melts from the ice of the mountains in each hemisphere. In doing so, small groups of archaeologists are scrambling to raise the funds and personnel needed to identify, recover and study these objects before they disappear.

Along with a group of scholars from the University of Colorado, the National Museum of Mongolia, and partners around the world, I work to identify, analyze, and preserve ancient materials emerging from the ice in the grassy steppes of Mongolia, where such discoveries have a huge impact on how scientists understand the past.

Life on the ice

During the hot summer months, unique plants thrive at the well-watered margins of the ice patches. Large animals such as caribou, elk, sheep and even bison look for ice to cool off or escape insects.

Because ice sheets are predictable sources of these plants and animals, as well as fresh water, they are important to the sustenance of nearby people almost everywhere they are found. In the dry steppes of Mongolia, water from melting mountain ice supplies summer pastures, and domestic reindeer seek ice much the same way as their wild counterparts. Global warming aside, the ice margins act as magnets for people – and deposits of the materials they leave behind.

It is not just their biological and cultural significance that makes ice patches important tools for understanding the past. Tangible objects made and used by early hunters or herders in many mountainous regions were constructed from soft, organic materials. These fragile objects rarely survive the erosion, weathering and exposure to harsh elements that are common in alpine areas. However, if tossed or lost in ice, objects that would otherwise degrade can be preserved for centuries in frozen conditions.

But the high mountains experience extreme weather conditions and are often far from the urban centers where modern researchers are concentrated. For these reasons, the important contributions of mountain dwellers to human history are sometimes overlooked in the archaeological record.

For example, in Mongolia, the high mountains of Altai were home to the oldest pastoral societies in the region. But these cultures are known only through a small some graves and the ruins of some windswept stone buildings.

More Ice Melt Artifacts

One of our discoveries was a piece of finely woven animal hair rope taken from a melting ice patch on top of a mountain in western Mongolia. While surveying, we spotted him lying among exposed rocks at the edge of the receding ice. The artifact, which may have been part of a bridle or harness, appeared to have been dropped into the ice the day before – our guides even recognized the traditional crafting technique. However, scientific radiocarbon dating has revealed that the artifact is actually over 1,500 years old.

Such objects provide rare clues to the daily lives of ancient herders in western Mongolia. Their excellent conservation allows us to carry out advanced analyzes in the laboratory to reconstitute the materials and choices of the first breeding cultures that eventually gave rise to pan-eurasian empires like the Xiongnu and the Great Mongol Empire.

For example, scanning electron microscopy allowed us to determine that camel hair was chosen as the fiber to make this rope bridle, while collagen preserved in the ancient tendon revealed that deer tissue was used to tie a Bronze Age arrowhead to its shaft.

Sometimes the objects that emerge end up overturning some of archaeologists’ most basic assumptions about the past. Locals in the area have long been classified as herding societies, but my colleagues and I found that Mongolian glaciers and ice sheets also contained hunting artifacts, like spears and arrows, and skeletal remains. big game such as argali sheep. covering a period of more than three millennia. These findings demonstrate that big game hunting on mountain ice has been an essential part of pastoral livelihood and culture in the Altai Mountains for thousands of years.

But time is running out. The summer of 2021 is shaping up to be one of the hottest on record, as scorching summer temperatures fry the rainforests of the Pacific Northwest and wildfires ravage the Siberian Arctic. The impact of rising temperatures is particularly severe in cold regions of the world.

In the area that my colleagues and I are studying in western Mongolia, satellite photos show that more than 40% of the ice-covered surface has been lost over the past three decades. Once each artifact is exposed by melting ice, there may only be a limited window of time for scientists to recover it before it is damaged, degraded, or lost due to the combination of freezing , thaw, weather, and glacial activity that may affect previously frozen artifacts. .

Due to the magnitude of modern climate change, it is difficult to quantify the amount of material lost. Many high mountains in Central and South Asia have never been systematically surveyed for molten artifacts. In addition, many international projects have not been able to continue since the summer of 2019 due to the COVID-19 pandemic – which has also led to cuts, salary reductions and even complete closures of archeology departments in the best universities.

Revealed by warming, providing climatic clues

Ice patch artifacts are irreplaceable scientific datasets that can also help researchers characterize ancient responses to climate change and understand how modern warming may affect the world today.

In addition to man-made artifacts left in the snow, ice patches also preserve ‘ecofacts’ – natural materials that trace important ecological changes, such as shifting tree lines or altering habitats of trees. animals. By collecting and interpreting these datasets along with ice artifacts, scientists can gather information about how people have adapted to significant ecological changes in the past, and perhaps expand the toolkit for making facing the climate crisis of the 21st century.

Meanwhile, the plant, animal and human communities that rely on shrinking ice sheets are also at risk. In northern Mongolia, my work shows that summer ice loss is harm the health of domestic reindeer. Local ranchers are concerned about the impact of ice loss on pasture viability. Ice melting is also converging with other environmental changes: in western Mongolia, animal populations have considerably decreased due to poaching and poorly regulated tourist hunting.

While the rising heat exposes artifacts that provide insight into ancient climate resilience and other important scientific data, the loss of ice itself reduces humanity’s resilience for years to come.

William TaylorAssistant Professor and Curator of Archaeology, University of Colorado at Boulder

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