Climate Change: Why Don’t All Alpine Peaks React the Same?

European mountains are transforming under climate warming, but not in the patterns scientists expected. A study published in August 2026 in Nature Ecology & Evolution challenges traditional models: local temperature increases explain only a fraction of the upheavals observed in alpine vegetation. The University of Vienna reveals that interactions between plant species are as decisive as the thermometer.

This phenomenon is already visible from space: the Alps are greening as a result of climate change, with consequences for snow and biodiversity.

• Researchers studied 724 plots across 53 European summits.
• Heat-adapted plants become more common with increasing altitude.
• Local temperature explains only part of the observed changes.
• The presence of thermophilic species facilitates the establishment of new plants.
• Cold-adapted species retreat, often without finding refuge higher up.

The paradox uncovered after 21 years of monitoring: a weak local correlation

Between 2005 and 2026, the GLORIA network (Global Observation Research Initiative in Alpine Environments) tracked 724 plots across 53 European summits, from Norway’s Alps to the Romanian Carpathians. Four successive surveys mapped the evolution of alpine flora with unprecedented precision. The surprise: at the scale of an individual plot, the direct link between local warming and the proliferation of heat-loving species remains strikingly tenuous.

“Our data clearly show that European summit vegetation is changing and that heat-adapted species are becoming more common. Yet the pace of these changes does not seem to depend solely on rising temperatures,” explains Johannes Hausharter, lead author of the study and biodiversity researcher at the University of Vienna. Warming acts as a regional driver, but other factors modulate how it translates into each summit’s reality.

Thermophilic species helping each other: the ecological network effect

The key to the mystery lies in a plant-enshrined mutual aid phenomenon. When a thermophilic species establishes itself on a summit, it facilitates the arrival of other heat-tolerant plants. Stefan Dullinger, project lead at the University of Vienna, summarizes: “The summit vegetation’s response to climate change depends not only on how many extra degrees there are, but also on the presence of thermophilic species already there.”

This mechanism of mutual reinforcement turns some summits into refuges for thermophile flora, while others resist more. Local ecological conditions (exposure, soil type, moisture) amplify or dampen the process, creating a mosaic of varied responses across Europe’s Alpine range.

This evolution unfolds in landscapes already strained by urbanization, tourism, and infrastructure. The Alps thus rank among the world’s most threatened ecosystems.

The winners and losers of the Alpine transformation

In Mercantour, the French Alps’ iconic range, Sempervivum montanum (mountain houseleek) has for the first time (2) breached summits previously beyond reach. A succulent plant with fleshy rosettes, it symbolizes the altitude-driven migration of thermophilic species. Its spread marks a ecological tipping point: cold niches shrink, while temperate zones advance upward along the vertical gradient.

Earlier work had already shown that new plants are blooming on European summits. The new study helps illuminate the mechanisms that promote their establishment.

By contrast, several emblematic glacial species are declining. Ranunculus glacialis (glacier buttercup), a white-flowered plant that colonizes scree near perpetual snow, has retreated in Norway and the Romanian Carpathians. Luzula alpinopilosa (Alpine tufted rush) has vanished from all summits surveyed in the High Tatras, at the Slovak–Polish border. Geum reptans (creeping avens) is thinning in the Italian Dolomites. Cold-adapted species rise higher, yet the mountains offer no shelter: above 3,000 meters, bare rock replaces vegetation.

These shifts aren’t limited to flora. A broad recent study showed that butterflies are already migrating in response to warming, with some expanding into new territories while others retreat.

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