Summary in One Sentence:
This 21-year longitudinal study, published in *Science*, is like conducting four rounds of precise “censuses” of 62 mountain peaks across Europe. It directly dispels the common misconception that “more plants are growing on mountain tops due to climate change, indicating an improvement in the ecosystem.” On the surface, the total number of species appears to be increasing, but in reality, it’s because common, temperature-loving plants from lower altitudes are moving up the mountains, pushing out the unique and rare species that have lived there for generations. The extinction rate has nearly doubled over the past 20 years. What’s more concerning is that because mountain plants have long lifespans and are slow to respond to environmental changes, the extinctions we are witnessing are just the beginning. The “extinction debt” we have accumulated will be realized in the future, with even larger-scale species losses to follow.
---
Point-by-Point Explanation:
1. A 21-Year “Census” That Eliminated All Previous Misconceptions
This study avoided the pitfalls of many previous ecological surveys. Instead of randomly selecting a mountain and counting a few plants, researchers installed nearly 1,000 permanent observation plots (each 1 square meter) on 62 mountain peaks across 16 European regions. They returned to the same locations in 2001, 2008, 2015, and 2022 to count the plants again. They even excluded natural fluctuations such as plants that temporarily went dormant and then reappeared. The final statistics only included confirmed extinctions that truly occurred within those areas. This level of rigor is akin to conducting a neighborhood census every seven years, where you would visit the same household each time to record the residents. If you only counted the number of people at the convenience store near the neighborhood entrance, you might mistakenly conclude that the total population had increased and that the original residents were still there. The resulting extinction rate of 9.9% is highly credible.
2. The Culprit Behind Extinctions: Every 0.1°C Rise in Temperature Leads to a 1%–1.6% Increase in Species Losses
The research team compared temperature increases with extinction rates and found that this explains 14%–36% of the observed changes. If we only considered the natural decline of species over time, this would only account for 3%–17% of the changes. The former explanation is more than twice as effective, indicating that climate change is the primary cause of the accelerated extinction of species. There’s a clear pattern: the lower the latitude and the more rapid the temperature rise in recent decades, the higher the extinction rates, similar to how in older urban areas with rising rents, long-standing residents are forced to move out more quickly.
3. An Increase in Species Is Not a Good Sign; It’s a Case of “Ecological Hollowing Out”
This is the most counterintuitive conclusion of the study. People often think that a higher species diversity means a healthier ecosystem, but this is a misconception. The new species that appear are “generalist plants” that can survive anywhere; the truly unique and rare mountain species that are disappearing are found only on those specific mountain peaks. This is similar to the “hollowing out” of cities, where the increase in the total number of restaurants (e.g., chain奶茶 shops and pre-prepared dishes) masks the disappearance of local, century-old, culturally significant businesses. The total number may increase, but the city’s unique cultural heritage and resilience are lost. If supply chain disruptions occur, these chain businesses can leave quickly, leaving the ecosystem empty.
4. We Already Have an “Extinction Debt” and Are Just Starting to Pay for It
The researchers coined the term “extinction debt.” Mountain plants are often very resilient, surviving for decades or even centuries. Even if the environment becomes unsuitable for them, they can rely on stored nutrients to survive. Therefore, the cumulative damage from climate change over the past few decades will not cause them to die immediately. The extinctions we see now are the result of changes that occurred decades ago, akin to overconsuming on a credit card and only starting to repay the principal and interest now. If we don’t control climate change, the scale of future extinctions will be much greater. Moreover, these unique mountain species have no way to adapt; moving to higher altitudes would leave them with nothing but rocks and air, leading to their complete extinction.
5. This Study Reminds Managers to Pay Attention to Marginal Warning Signs
The study also identified a useful warning indicator: if the range of a species in a particular area shrinks for several years in a row, the probability of its extinction is 2.5 times higher than normal. This is similar to a company’s declining revenue, which significantly increases the likelihood of bankruptcy. Ecological protection efforts should focus on this early warning, rather than just the total number of species. Many places have focused on the total number of species, leading to the loss of valuable, unique species. Similarly, economic development often prioritizes GDP, driving out local industries and replacing them with more adaptable businesses, resulting in a pleasing overall figure but losing local competitiveness. This study serves as a reminder: we should intervene before rare species are completely lost. We should act when their habitats shrink year by year, before they are pushed to the brink with no options left.