Climate change reveals secrets of our ancestors hidden in the ice
The Age of Melt: What Glaciers, Ice Mummies, and Ancient Artifacts Teach Us About Climate, Culture, and a Future Without Ice Lisa Baril Timber (2024)
As an avid hiker, I’ve often noticed patches of snow tucked along ridge lines even in late summer in North America’s Rocky Mountains and other mountain ranges around the world. I assumed they were just left over snow from the previous winter, or perhaps from a few recent winters. It turns out I’m probably wrong. Many of these inconspicuous ice patches might have persisted for 10,000 years or more, and some contain a trove of unique ancient artefacts and climate information.
In The Age of Melt, science journalist Lisa Baril takes the reader on a well-crafted and entertaining journey into Earth’s frozen realms. This ‘cryosphere’ includes the great polar ice sheets in Greenland and Antarctica, sea and lake ice, permafrost, mountain glaciers and semi-permanent ice patches. Baril focuses on the last two categories, because they exist at mid- and low latitudes, where the most people live and have direct contact with ice. It is this interaction between humans and the ice — in the past, present and future — that most interests the author.
The journey starts high in the Alps, on the border between Italy and Austria, with the 1991 discovery of a human body revealed by the melting of an ice patch. The body and belongings of Ötzi, as he has become known, had been preserved for more than 5,000 years. This was possible thanks to the characteristics that distinguish ice patches from glaciers. Glaciers flow slowly downhill, pulled down by their own weight, moving ice from colder and wetter upper regions to warmer, drier lower regions, where the ice melts. This flow results in continual replacement, so the ice in most mountain glaciers is less than a few centuries old. Moreover, the flow rapidly buries, crushes and tears apart any material that falls onto a glacier. Ice patches are smaller and thinner than glaciers, and do not flow. This means that the ice is not replaced, and so can be thousands of years old. If conditions are right, materials that fall onto an ice patch’s surface can be frozen and preserved with little alteration.
As Baril discusses, many of Ötzi’s belongings were composed of once-living organic materials, such as plant fibres, wood and leather, that, together with his body, would soon have decayed had they not been frozen. Unlike inorganic artefacts made of stone or metal, the age of these organic objects can be determined accurately using carbon dating. The discovery of Ötzi’s spectacularly preserved body and belongings provided researchers with a unique window into Neolithic civilization in the Alps, and launched a field called ice-patch archaeology.
The body of the prehistoric hunter Ötzi was buried in ice on the Italy–Austria border for more than 5,000 years.Credit: Leopold Nekula/Sygma/Getty
Baril meets with and talks to archaeologists and others studying ice patches and the cultural materials that are being disentombed from them in Europe, North America and Asia. One site she visits is a 70-metre-long tunnel carved into the Juvfonne ice patch in Norway, built in 2012. Here, evidence has emerged of humans hunting and herding reindeer as early as 6,000 years ago. Many of the ancient artefacts exposed by melting ice patches around the world relate to large-animal hunting. In summer, reindeer (caribou), bison, mountain sheep and other large animals would congregate on ice patches to avoid heat and biting insects, and autumn melt would support late-season grass growth, making the patches into high-elevation oases. Hunters followed the herds, as shown by lost and discarded hunting tools, along with everyday items, such as shoes, clothing and baskets, that accumulated and were preserved in the ice patches.
Through interviews and field trips in the Rocky Mountains, Canada’s Yukon province and elsewhere, Baril interacts with Indigenous people whose traditional lands include artefact-bearing ice patches and culturally important mountain glaciers. It was the accidental discovery in 1997 of apparently fresh caribou dung melting out of an ice patch in the Yukon where caribou (Rangifer tarandus) had been absent for 60 years that first alerted people to the idea that ice patches in the area might be much older than thought. This was confirmed by the discovery of a ‘twig’ emerging from the ice patch that turned out to be a 5,000-year-old atlatl, a lever used to propel darts that preceded the bow and arrow by thousands of years. These and subsequent discoveries launched a continuing collaboration between Yukon government archaeologists and First Nations governments to monitor and regularly survey for artefacts in melting ice patches over a vast region, including the traditional lands of six First Nations in Canada.
During her journey, Baril joins interdisciplinary teams of archaeologists and climate scientists in the field and in the laboratory as they study ice patches and glaciers in the Rocky Mountains. It was here in 2007 that Craig Lee, an archaeologist now at Montana State University in Bozeman, stumbled across the oldest ice-patch artefact yet found — the foreshaft of an atlatl made from a birch-bark sapling, shown by carbon dating to be 10,300 years old. Dating plant material encased in organic-rich layers in the same ice patch also revealed that layers of ice had been added to the patch throughout the past 10,000 years, preserving an unparalleled record of high-elevation climate variability in the Rocky Mountains.
Baril ends her journey looking at present and future interactions between humans and alpine ice. In South America, she joins a pilgrimage with Quechua-speaking people to the retreating Qolqepunku Glacier in the Peruvian Andes. She recounts efforts to replace declining summer river flows from shrinking Himalayan glaciers through the creation of conical heaps of ice, known as ice stupas, that slowly melt and release water during the growing season.
Fossil-fuel burning has resulted in atmospheric levels of carbon dioxide and other greenhouse gases that Earth has not seen for three million years. The ice retreat of the past few decades is among the most obvious manifestations of the resulting climate warming. The extraordinary and unexpected insights into earlier cultures and climates brought by artefacts revealed in rapidly melting ice is one expected upside. The downside for all of us is that these insights are produced from the loss of majestic mountain glaciers and the ecosystem services they provide. As Baril points out, the field of ice-patch archaeology itself might be as fleeting as the ice patches it studies. Once the ice melts, these links to the past will be lost to history, placing humanity one step closer to a future climate never known by our ancestors — but one inherited by our children.
