Mountains cover nearly a quarter of the Earth's surface and directly or indirectly support more than half of the world's population by providing essential ecosystem services: they supply fresh water to large cities and agricultural regions, regulate local and regional climate, store carbon in forests and peatlands, conserve unique biodiversity, and provide essential resources for culture, recreation, and well-being. However, in recent decades they have become one of the areas where global change is manifesting itself most intensely and rapidly. Far from being remote or unchanging territories, they are undergoing a profound transformation with far-reaching ecological, economic, and social consequences.
This occurs because these territories are particularly sensitive to global warming, which in mountain areas far exceeds the average . This increase in temperature is causing accelerated snow loss and glacier retreat, with direct effects on hydrological regulation. Many of the world's most important rivers depend on snow and glacier balance to maintain their flow, so the reduction in snow cover and premature melting are altering seasonal water flows, generating more runoff in winter and less in summer, when agricultural and urban demand is highest. Therefore, this imbalance not only affects biodiversity, but also human supply, hydroelectric production, and food security.
Global warming also exerts strong pressure on high mountain biodiversity, one of the most unique and fragile on the planet. Many species are moving to higher altitudes in search of cooler temperatures, but in mountain systems, the altitudinal range is limited. As a result, species adapted to cold environments, from alpine plants to birds, insects, and amphibians, are increasingly cornered and, in some cases, on the verge of local extinction. Added to this are imbalances in physiological cycles that generate increasing asynchrony between species that depend on each other. These changes have an impact on essential ecological processes such as pollination, pest control, and nutrient cycling.
Added to these pressures is growing human influence. Increased tourism, urbanization of valleys, infrastructure construction, and growing demand for water and energy are rapidly transforming mountain ecosystems. This increase in land use is displacing native species and altering the ecological balance, especially in areas of high environmental sensitivity.
There is also a less visible but equally decisive factor: atmospheric deposition of pollutants, especially nitrogen and phosphorus. Although often perceived as isolated spaces, mountains receive increasing amounts of nutrients from human activities located at great distances. In many oligotrophic systems (i.e., adapted to very low nutrient levels) such as peat bogs, alpine meadows, high mountain soils, or glacial lakes, these inputs already exceed their critical ecological loads, altering the Chemistry the water, promoting algal blooms, and displacing native species adapted to nutrient-poor environments. As a result, the capacity of these ecosystems to purify water, store carbon, or maintain their characteristic biodiversity is diminished.
The impact of global change on mountain areas is therefore clearly multifactorial. The combined effect of climate change, the decline in extensive livestock farming, air pollution, and increased construction pressure is increasing the frequency and intensity of extreme events and forest fires and transforming iconic elements of the landscape: glaciers are disappearing, peat bogs are degrading, forests are rising in altitude or changing in composition, and high-altitude lakes are undergoing unprecedented chemical and biological alterations. This set of changes directly affects core topic activities core topic local communities, such as extensive livestock farming, tourism, food production, and water supply. Intensified human pressure amplifies these effects and accelerates the degradation of ecosystems that are fragile by nature. If this trend continues, mountain regions will face profound challenges in maintaining their economic pillars and the way of life of their communities.
Due to their sensitivity and strategic role in the functioning of the planet, mountains have become true sentinels of global change. What happens in them anticipates climatic and ecological scenarios that will affect other regions in the coming decades. Protecting their ecosystems and strengthening their resilience is essential to guarantee the ecosystem services that sustain millions of people and to preserve a natural heritage of incalculable value. In this context, in the coming years it will be essential to consolidate and expand cross-border mitigation and adaptation strategies in mountain regions, following the example of pioneering initiatives in Europe such as the Pyrenean Climate Change Strategy (EPiCC) and theLIFE Pyrenees4Clima project , which promotes its implementation.
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David Elustondo
Full Professor Environmental Technologies
Director of Biodiversity and Environment Institute at the University of Navarra.
article in "The Conversation Spain."
