The cryosphere, sum of all frozen water on the globe, is a critical component of the Earth’s systems. It is undergoing unprecedented transformations under the changing climate. These changes have profound implications for the atmosphere, hydrosphere, geosphere, and biosphere, ultimately affecting water resources both in quantity and quality.

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About 70% of Earth’s freshwater exists as snow or ice1, making the cryosphere the largest reservoir of freshwater. It plays a pivotal role in the water cycle (see the Perspective by van Tiel et al. in this issue) by regulating water availability through various processes such as melting, freezing, and thawing. This regulation is essential for sustaining water supplies, especially in regions that heavily rely on meltwater. For example, the glaciers in the high mountains often serve as a natural water tower, storing water in the form of ice and snow during the winter and releasing it during the summer. This meltwater is vital for drinking water, agriculture irrigation, and hydroelectric generation for people downstream. Changes in these glaciers directly impact water supplies, food security and human well-being (see the Comment by Emmer in this issue). As the high mountain cryosphere melts, water quality is also likely to be affected all the way along the elevation gradient, from headwater to downstream, for example, by the release of legacy pollutants stored in ice and snow.

The cryosphere also influences Earth’s climate through its high surface reflectivity, known as albedo. Around 10% of Earth’s land area is covered by glaciers or ice sheets1, reflecting a substantial portion of solar radiation, thus regulating the planet’s temperature. As glaciers melt, ice sheets decrease, the Earth absorbs more heat, accelerating global warming, sea level rise and further melting.

Moreover, the cryosphere is integral to the health of many ecosystems (see the Comment by Liljedahl et al. in this issue). Beyond human communities, many plants and animals depend on it. Polar regions, for instance, are home to unique biodiversity that relies on ice-covered and snow environments. Rapid changes in these environments threaten species such as ibexes, polar bears, and penguins, affecting their breeding grounds and disrupting entire food chains.

The cryosphere is shrinking, posing challenges to water supplies, climate system and biodiversity. It’s time to act together for a better understanding of the cryosphere and its interactions between Earth’s systems. Addressing the complexities of cryosphere research requires the integration of knowledge and methods from multiple disciplines. In his World View, Jan Karlsson calls for increasing collaborations across fields and using a combination of approaches to assess the climate impact and feedback on the Arctic carbon cycle. In another World View discussing the feasibility of glacier preservation, Matthias Huss points out that hydrologists, glaciologists, ecologists, material scientists or sociologists working together might help local glacier melt reduction and benefit the local communities.

Collective efforts are also essential in fieldwork, where direct and firsthand observations and measurements of all components of the cryosphere are obtained. Fieldwork allows researchers to observe and analyse both historical and real-time changes in snow covers, ice sheets, glaciers, and all other ecosystems. The collected data are crucial for validating models and predictions, enhancing the accuracy and capacity of our understanding of cryosphere dynamics. In a Q&A, Olga Makarieva, Åsa Rennermalm and Emily Youcha stress the importance of leveraging diverse expertise and resources — from scientists and technicians to logistics support, funders, local communities, and even one’s family — for successful field expeditions.

While data acquisition is critical, it can’t solve all our questions about the cryosphere. Data sharing and open access to cryosphere data enable researchers worldwide to collaborate, to share knowledge and to make scientific progress. No single country or organization can tackle the challenges alone. By sharing data and research findings, researchers and practitioners can develop a more comprehensive understanding of cryosphere dynamics and facilitate more effective global strategies for adaptation and mitigation.

Saving the Earth’s frozen water is a longstanding endeavour, spanning generations, as witnessed by historical field stations, ongoing initiatives, and the education of the next generations (see the Q&A in this issue). Lettie Roach, in her World View, outlines three key areas for accelerating Antarctic research from an early-career perspective, broadly applicable to all cryosphere studies: promoting inclusivity in the scientific community, enhancing scientific communication, and re-evaluating academic priorities. By fostering collaborative and inclusive approaches to cryosphere research, we can better comprehend and mitigate the impacts of its transformation in response to climate change. The sustainability of water resources and the health of ecosystems depend on studying and protecting this vital component of Earth’s systems. Let us work together to safeguard the cryosphere for the benefit of current and future generations.