This month, the attention of approximately 2 billion people will once again be drawn to mountains, as the 2026 Winter Olympics take place in the Italian Alps. As a backdrop to the competitions, viewers will also witness signs of changing mountain landscapes: many of the events will take place on artificial snow in otherwise snow-free landscapes. This inspires more debate on the environmental footprint of the games1, and the number of locations that will be able to host them in the future is decreasing rapidly2. But the changes the spectators of the winter games will see are only the tip of the iceberg.

High-altitude regions are among the fastest changing regions in the world3 and this has wide implications, which go far beyond the melting of ice. In this Focus issue, we highlight some of the diverse ways in which mountain regions are changing, as well as how this affects humans living both within them and farther away in lowland areas.

The most obvious change in mountains is a lack of snow and a shrinking of glaciers. In some cases, this melt has already led to the full disappearance of glaciers. In this issue of Nature Climate Change, Lander Van Tricht and colleagues show that this disappearance of glaciers will accelerate over the coming years and will peak in the 2040s with up to 2,000–4,000 glaciers disappearing per year.

As a feature of their topography, mountain ranges contain many different microclimates in relatively narrow spaces, forming distinct habitats for species survival. Research by Qing Tian and Feng Tian focuses on the differences between opposing sides of a single mountain (for example, polar-facing and equatorial-facing slopes), and shows that the differences in vegetation growth between the slopes has been weakening in the past two decades. In a Comment, Alejandro de la Fuente and colleagues discuss how the combination of complex topography and rapid change found in mountains acts as a natural laboratory to gain mechanistic insight into ecosystem responses to climate change, which can, in turn, inform adaptation options elsewhere.

It is important to remember that these mountain ranges are not isolated regions but are intrinsically connected to distant lowland regions, primarily through their key role in the water cycle, as most of the big rivers in the world originate at high altitudes. In a Perspective article, Daniel Viviroli and colleagues present an overview of the many ways water supply and transfer in mountains changes and how this affects the water supply of billions of people living in downstream lowland areas.

People living within mountain ranges face severe challenges as their environment changes, massively transforming their way of living. For example, shifting climate and ecosystem zones affect food production, while increasing hazards demand protective infrastructure. Declining snow and glacier cover makes tourism, especially during the winter season, unsustainable in many regions, impacting income sources for local communities. A Comment by Emmanuel Salim and colleagues focuses on the impacts of climate change on mountain tourism and highlights specific adaptive demands and choices.

Climate change does not only affect the economic situation of people but also has a more personal and spiritual dimension. In many regions, mountains and glaciers hold an important position in local traditions and beliefs. In a Viewpoint article, six researchers discuss how people in different parts of the world transform their religious practice in response to warming. These contributions show the strong impact that melting ice has on people’s spirituality and cultural practices but also highlight their role as protectors of their environment.

Last year was designated the International Year of Glaciers’ Preservation by the United Nations. The articles in this issue show that preserving mountain landscapes is not only relevant owing to their physical importance, but also because mountains allow people to understand global warming on an emotional and spiritual level. As such, climate change in the mountains can open the door to meaningful action and motivate broader climate mitigation efforts that go beyond their peaks.