1. Why the cryosphere

Decades ago, when climate change was still called “global warming” and a younger Donald Trump was known as the quiff dude in goofy cameos, attempts to raise climate-change awareness were already in place. They would often involve some image of a beaten polar bear balancing on a floating chunk of ice, or grandpa’s old photos of a mighty glacier snout that gradually gave way to a silty moon-like landscape. Such early uses of natural ice as the canary in the coal mine highlight the pivotal role played early on by the cryosphere to announce the shape of things to come.

It is not just a matter of ice being sensitive to warm temperatures. The situation is more complicated than that. First, it also has to do with some complex climate phenomena, like ice–albedo feedback, polar amplification, elevation-dependent warming, and glacier response time [1] (see Box 1). Melting glaciers and ice sheets have been the largest contributors to global mean sea-level rise over the last two decades [2]. In particular, Antarctica and Greenland store so much frozen water to potentially rise sea levels globally by over 65 meters [3]. While a complete disintegration of these ice giants is unlikely to happen in the near future, these figures make it clear that even fractional changes in the mass balance of ice sheets can lead to massive discharges of fresh water, severely affecting sea levels and thermohaline currents, and possibly even triggering tipping points (i.e., abrupt and/or irreversible changes) [2]. Lastly, natural ice provides the most precise and reliable continuous records of more than 800,000 years of Earth’s climate history [4], which with new studies may soon surpass the million-year mark.

Beyond its climatic importance, the cryosphere is also crucial for life: glaciers are vital sources of water, not only for a wide variety of ecosystems, but also for three billion people worldwide [5]. For this reason, glaciers are often affectionately dubbed “the water towers of our planet.” This fondness for glaciers is widespread and deep-rooted in human culture, going far beyond the mere appreciation of an ecosystem service. For millennia, diverse cultures around the world have developed intimate social relations with their glaciers, regarding them as living organisms, often even sentient members of the community.

For instance, in Yukon and Alaska there is the traditional belief that cooking grease or fat meat near glaciers is an offensive hubris that may be punished with deadly glacier surges or outburst floods [6]. The glaciers’ sentience is so subtle that even a disrespectful attitude towards venerable beings or the glaciers themselves may provoke similar catastrophic retaliations. On the other hand, in the Karakoram, the Balti people developed over centuries the practice of grafting new glaciers on strategically selected sites, by laying together blocks of “male” and “female” ice from gendered glaciers, together with carefully selected twigs, straw and cloth [7]. After many years of snow accumulation, these young glaciers evolve into natural reservoirs of frozen water to alleviate periods of drought.

Despite industrial and technological revolutions, the truth is that the notion of glaciers as sentient beings has never completely vanished from our worldview. Climate change has recently unearthed these concealed insights, for instance through the recent practice of reaching remote locations to mourn the death of glaciers, holding glacier funerals, and erecting memorials commemorating the loss of our icy companions [8,9]. Today, science is re-evaluating the intricately multidimensional relationships between human and nature, rediscovering the importance of the local and traditional knowledge of sentient glaciers for sustainable water management and glacier preservation [10].

For all those reasons, it comes as no surprise that the United Nations General Assembly has declared the period from 2025 to 2034 as the Decade of Action for Cryospheric Sciences, with 2025 designated the International Year of Glaciers’ Preservation, and with 21 March marked annually as World Glaciers Day. For 2025, various global and national events are planned (https://www.un-glaciers.org). These initiatives aim to raise awareness about the vital role of glaciers, snow, and ice for Earth’s climate and environment, highlighting impacts on sea-level rise, the water cycle, and related economic and societal effects. Above all, they serve as urgent calls for collective action, inciting world leaders to reflect upon the climate crisis and the threat of a decaying cryosphere.

2. Prospects

Decades ago, when extreme events fuelled by atmospheric CO₂ concentrations above 400 ppm belonged to science fiction, Carl Sagan [11] wrote: “Our civilization runs by burning the remains of humble creatures that inhabited the Earth hundreds of millions of years before the first humans came on the scene. Like some ghastly cannibal cult, we subsist on the dead bodies of our ancestors and distant relatives.” Today, with atmospheric CO₂ concentrations ramping up beyond 420 ppm and on the way to smash 450 ppm by 2035, damaging extreme events are becoming commonplace, like a chronic planetary disease, and planetary tipping points are becoming dangerously less unlikely. And yet, alas, the “ghastly cannibal cult” persists, no longer subsisting only on “dead bodies”, but also on the livings and lives of the most vulnerable.

Dying glaciers are emblematic reminders that climate change is, before all, a moral issue [12]. We shall not slight their swan song. Many glaciers may vanish by 2034, but others will continue to nourish and marvel us: they deserve preservation. Today, the major challenges facing glacier preservation cannot be resolved solely by expert authority. They require the collaboration of various actors, both scientific and non-scientific, through transdisciplinary approaches merged with various forms of knowledge [13] , by recognizing—as reminded by Karl Popper [14]—“how little we know, and how much that little is due to people who have worked in many fields at the same time.”

Let us make this Decade of Action for Cryospheric Sciences worthwhile. Coordinated collective action is the key. We do know what to do. Our world leaders do know what to do. What is holding back action is not lack of knowledge. It is lack of unfeigned willingness.