European scientists have sounded an alarm about the health of alpine ecosystems. While satellite images and field surveys show that mountain summits are becoming greener and more species‑rich, a new study published in Science reveals that many native high‑elevation plants are disappearing at an increasing rate.
Twenty years of data from 62 summits
The research team, part of the global GLORIA monitoring program, revisited 62 summits across 16 European ranges four times between 2001 and 2022. By comparing species lists from each survey, they identified which plants failed to reappear and examined the environmental conditions that preceded those local extinctions.
Results show a clear pattern: summits that experienced stronger warming saw a higher proportion of lost species. The loss was especially pronounced for plants that lived near the lower edge of their elevation range and for those that were already adapted to warmer conditions—a process scientists call “thermophilization.”
More species overall, but at a cost
Warmer temperatures have allowed many lower‑elevation species to move upward, boosting the total count of plant species on mountaintops. However, this apparent success masks a troubling trade‑off. Specialists that once thrived only at the highest elevations are being outcompeted and, in many cases, disappearing entirely.
“Until a few decades ago, short vegetation periods, low temperature sums and year‑round frost risk made alpine landscapes difficult to colonize for many species of the European flora,” said study first author Johannes Wessely of the University of Vienna. “Accelerating climate warming has relaxed these constraints, allowing species to expand upward. Yet the losses of high‑elevation specialists are rising alongside the gains.”
An early warning of an extinction debt
Co‑ordinator Harald Pauli of the Austrian Academy of Sciences explained that the lag between environmental change and species loss creates an “extinction debt.” Species that are long‑lived and stress‑tolerant may persist for years after conditions become unfavorable, only to vanish later when the cumulative stress becomes too great.
“The data clearly show that species were more likely to disappear from summits which experienced stronger warming,” Pauli noted. “This correlation was even stronger than the simple passage of time, indicating that temperature rise is the primary driver.”
Implications for conservation
The findings suggest that conservation strategies focused solely on increasing species counts may overlook the hidden loss of unique alpine flora. Protecting high‑elevation habitats, monitoring temperature trends, and mitigating climate change remain essential to preserving these irreplaceable ecosystems.
Project coordinator Stefan Dullinger added, “If the extinction debt is being paid off now, it underscores the urgency of addressing climate warming before more species are lost forever.”
As the planet continues to warm, the study serves as a reminder that a greener appearance does not always equate to ecological health. Ongoing monitoring and proactive stewardship will be crucial to safeguarding the biodiversity of Europe’s iconic mountain ranges.
Original reporting: KTBS 3 (Shreveport) — read the source article.
