As global temperatures continue to rise, scientists have worried that mountain species are on an "extinction elevator"—forced to move uphill for cooler temperatures, ultimately accelerating extinction as they run out of space. However, a new study has challenged this idea by analysing global data. Their research shows that actual evidence for this scenario is weaker than previously thought, offering a fresh perspective on how species are coping with climate change.

Science Media Center Taiwan (SMCTW) invited experts to share their views.

Expert Reaction

May 15, 2025
Professor Tzung-Su Ding is from the School of Forestry and Resource Conservation at National Taiwan University

Q1. What do you think is the most important finding of this study?

I believe the key takeaway is that this study highlights the ecological resilience of living organisms. Unlike inanimate matter, living organisms can respond to environmental stress through physiological, behavioral, and even physical adaptations. These changes can lead to population-level evolution, helping reduce the impact of environmental change. This is one of the biggest differences between biology and fields like physics or chemistry.

The core finding of the study challenges the widely held assumption that mountain species will face rapid extinction due to climate warming—the so-called "extinction elevator" hypothesis. By analyzing large datasets from mountainous regions around the world, the researchers found that mountaintop species have not experienced a widespread or significant shrinkage in their range.

Even more interestingly, many species—especially those with small ranges or living at lower elevations—are actually expanding their vertical range upward.

This is likely because the geometric shape of mountains offers available space at higher elevations. Combined with the species’ existing ability to tolerate a range of environmental conditions, this allows them to move upward rather than simply being pushed into extinction.

Overall, the study shows that many species have a higher potential for adaptation to climate warming than previously thought.

Q2. Based on your own research and observations in Taiwan, have you seen similar trends?

Yes. With support from Yushan National Park in Taiwan, I conducted bird surveys at elevations between 1,400 and 3,700 meters on Yushan’s main peak in 1992, 2014, and 2024, using the same methods and team.

Between 1992 and 2024, air temperatures in breeding season in the high mountain area increased by 0.8°C. During this period, the breeding ranges of 50 bird species shifted upward by an average of 155 meters. Among them, 69% of the species significantly increased their elevational distribution, while only 11% significantly decreased.

Interestingly, the rate of increase over the last 10 years was even higher than during the previous 22 years.

For example, Alpine Accentor (Prunella collaris), a bird species found only at the highest elevations in Taiwan, has experienced a slight contraction in its elevational range. However, it has not faced the extreme extinction risk once predicted, and has maintained a stable population and range. This observation is consistent with the findings of the study.

Q3. How might this research affect Taiwan? What conservation policy adjustments might be needed??

This study offers a global perspective on how mountain species are responding to climate change. It challenges earlier, more pessimistic predictions and highlights the importance of mountain geometry and species' adaptive potential.

It also suggests that “biotic homogenization”—where biological communities in different regions become more similar—might be one of the more visible ecological consequences.

That said, the study does not directly examine the effects on specific regions or species in Taiwan.Our mountains have unique geography, species composition, ecological interactions, and face additional non-climatic threats like habitat destruction and invasive species.

These differences mean we need local data to properly assess how the study’s findings apply to Taiwan and whether policy adjustments are needed.

Still, the analytical framework used in this study—including the emphasis on mountain geometry and biotic homogenization—can serve as an important reference for future research and conservation planning in Taiwan."

Reference

[1] Liao, H.-C., Lin, D.-L., Huang, C.-Y., and Ding, T.-S.(2014). "Altitudinal Distribution and Population Densities of Alpine Grassland Birds in Yushan National Park." Journal of National Park, 24(1): 28-39

[2] Chan, S-F., Rubenstein, D. R., Chen, i-C., et. al. (2023). "Higher temperature variability in deforested mountain regions impacts the competitive advantage of nocturnal species." Proceedings of the Royal Society B.

[3] Chen et al., (2011) "Rapid Range shifts of Species associated with High levels of Climate Warming." Science 333, pp. 1024-1026. DOI:10.1126/science.1206432

[4]Chen et al., (2009)  "Elevation increases in moth assemblages over 42 years on a tropical mountain." The Proceedings of the National Academy of Sciences, 106 (5): 1479-1483. DOI:10.1073/pnas.0809320106

[5]Previous studies of that climate change signals are pronounced in mountain regions:

[6]Chen, I. C., Hill, J. K., Shiu, H. J., Holloway, J. D., Benedick, S., Chey, V. K., ... & Thomas, C. D. (2011). Asymmetric boundary shifts of tropical montane Lepidoptera over four decades of climate warming. Global Ecology and Biogeography, 20(1), 34-45.

[7]Lin, W. C., Lin, Y. P., Lien, W. Y., Wang, Y. C., Lin, C. T., Chiou, C. R., ... & Crossman, N. D. (2014). Expansion of protected areas under climate change: an example of mountainous tree species in Taiwan.Forests, 5(11), 2882-2904.

[8] Kuo, C.-C., Liu, Y.-C., Su, Y., Liu, H.-Y., & Lin, C.-T. (2022). Responses of alpine summit vegetation under climate change in the transition zone between subtropical and tropical humid environment.Scientific Reports, 12(1), 13352.

[9] Price, M. V., & Waser, N. M. (1998). Effects of experimental warming on plant reproductive phenology in a subalpine meadow. Ecology, 79(4), 1261–1271.

[10] Butt, N., Seabrook, L., Maron, M., Law, B. S., Dawson, T. P., Syktus, J., & McAlpine, C. A. (2015). Cascading effects of climate extremes on vertebrate fauna through changes to low-latitude tree flowering and fruiting phenology. Global Change Biology, 21(9), 3267–3277.

[11]Walters, A. W., Mandeville, C. P., & Rahel, F. J. (2018). The interaction of exposure and warming tolerance determines fish species vulnerability to warming stream temperatures. Biology Letters, 14(9), 20180342.

[12]Pallarés, S., Colado, R., Botella-Cruz, M., Montes, A., Balart-García, P., Bilton, D. T., Millán, A., Ribera, I., & Sánchez-Fernández, D. (2021). Loss of heat acclimation capacity could leave subterranean specialists highly sensitive to climate change.Animal Conservation, 24(3), 482–490.

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