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Species living in 17 mountains around the world are facing the risk of extinction due to the rapid rate of warming attributed to climate change. However, the establishment of additional meteorological monitoring stations in mountainous areas globally is essential for a deeper understanding of the extent of these threats. Climate velocities track the rate of climate condition changes, illustrating the speed at which species must move to stay within their survivable habitats. The study identified regions with notably high climate velocities encompassing 17 mountain areas, ranging from the Alaska-Yukon territory to Sumatra and from the Mediterranean to Japan, overlapping with several biodiversity hotspots. 

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

• Research: Chan, W.P., Lenoir, J., Mai, G-S., Kuo, H.-C., Chen, I-C., Shen, S.-F. (2024). "Climate velocities and species tracking in global mountain regions." Nature
• Media Release： Study estimates mountain climate velocities for the first time: 17 mountains at high risk of losing biodiversity under climate change

Expert Reaction

March 22, 2024
Dr. Shen, Sheng-Feng, Researcher at the Biodiversity Research Center of Academia Sinica (corresponding author of the article)

Q1. Why is it so important to understand the effects of climate change on temperature changes in mountainous areas? What do you think is the most important finding of this study for the general public?

Compared to the number of weather stations and accumulated information in earth surface areas, meteorological monitoring data in mountainous areas is very scarce. Not only is there a lack of sufficient stations, but there are also few stations that have accumulated about 40-50 years of meteorological data to understand climate change trends. However, mountainous areas are characterized by high biodiversity, high vulnerability to climate disasters, and high impact on local livelihoods. Without sufficient meteorological data, it is difficult to properly assess the impact of climate change on mountainous areas.

Therefore, the main result of this study is to develop a calculation method that uses satellite data, surface warming data, and thermodynamic model to calculate two important factors that affect the rate of temperature change in mountainous areas: the degree of surface warming and water vapor pressure. This method compensates for the lack of empirical data and assesses the climate velocities of global mountainous areas under climate change.

Using this method, our study listed the top 20% of the fastest warming mountainous areas, including 17 regions such as the Alaska-Yukon area in Canada, mountainous areas in Japan, and the Putorana Plateau and Kamchatka Peninsula in Russia (see Figure 3 in the main text). Identifying the most important mountainous areas threatened by climate change allows the formulation of appropriate strategies for biodiversity conservation and adaptation to climate change.

Q2. What do you think are the limitations of this study? Is it possible to understand the situation in Taiwan from a global perspective?

The scarcity of meteorological observation data in mountainous areas is both the most important value and the biggest challenge of this study. In the absence of direct data, calculations and estimates must be made using models, but different models and calculation methods can lead to discrepancies in results. Previous studies have estimated that the explanatory power of climate change on the movement of mountain species is only about 5%. The model in our study has significantly increased the explanatory power by three times to about 15%, but the results still have uncertainties.

In addition, due to data scale limitations, it is not appropriate to use global data to estimate conditions in local regions. For example, in Taiwan, it is difficult to accurately estimate the temperature conditions of certain mountainous areas, such as the Jade Mountains, using the average surface temperature. However, the assessment results of the study can indicate areas that need priority attention for data accumulation, research, and formulation of response strategies.

Given the complex nature of different mountainous areas and the lack of local data, the absence of marked regions does not imply a lack of impact. We believe it is crucial to establish additional mountain meteorological monitoring stations to gain a deeper understanding of the actual conditions and address the impacts of climate change on species.

Q3. Previous research by the Taiwan Climate Change Projection and Information Platform (TCCIP) found that between 1911 and 2020, the average warming in Taiwan was greater than the global average. Could this have a greater impact on species and their migration rates in Taiwan's mountainous areas?

A more positive piece of news from the results of this study is that Taiwan's mountainous areas are not among the top 20% of the fastest warming mountainous areas in the world. Our study compares the decadal average temperatures from 1971-1980 and 2011-2020, and shows trends that high-latitude areas have faster surface warming rates and lower humidity, driving the warming rate of mountainous areas. Interestingly, in low-latitude areas with slower surface warming rates, we also observed mountainous areas with particularly fast warming rates, including Japan, the Mediterranean region, the Brazilian highlands, and the mountains of North Sumatra.

In addition, Taiwan's mountainous areas only have some weather stations, but some stations have relatively long-term observational data, such as the Jade Mountain weather station, providing an opportunity to observe long-term trends in mountainous temperature changes. Previous ecological surveys[1] have also observed the phenomenon of species habitat shifting upward. However, compared to other regions, Taiwan still has some time to accumulate research data and formulate response strategies.

Q4. International reports continue to warn that delays in global mitigation will make it difficult to avoid scenarios where warming exceeds 1.5 degrees Celsius. In such a situation, what strategies or methods do we have to protect mountain biodiversity?

An important factor in preserving the biodiversity of mountain areas and increasing their capacity to adapt to climate change is to maintain larger and more connected forests. This is because forests provide habitats for many species and have the function of regulating microclimates. Previous research[2] has shown that large-scale development and deforestation exacerbate diurnal temperature variations in the area, increasing the threat to species survival. Therefore, maintaining forest integrity, reducing mountain development, and reducing large-scale deforestation will be important strategies for protecting mountain biodiversity.

March 22, 2024
Prof. Chen, I-Ching, Assistant Professor, Department of Life Sciences, NCKU (corresponding author of the article)

Q1. Why is it so important to understand the effects of climate change on temperature changes in mountainous areas? What do you think is the most important finding of this study for the general public?

This is the first global analysis of climate velocity in mountain regions, setting a benchmark for assessing biological responses with profound implications for biodiversity conservation. We identify 17 mountain regions with relatively high climate velocities, covering 32% of the world's mountain areas, ranging from Alaska-Yukon to Sumatra, from the Mediterranean mountains to Japan, overlapping with several biodiversity hotspots, highlighting the extensive threats to global mountain biodiversity.

Climate velocity in mountains refers to the rate of movement of isotherms along elevation (usually measured in m/year), which represents the speed at which organisms must move to maintain optimal temperature conditions. There are two factors affect the speeds  of isotherm movements: the rate of surface warming and the lapse rate of temperature, with humidity being a key factor affecting the latter. However there is a notable lack of meteorological stations in mountain areas, it has been difficult to obtain local data on temperature and humidity, thus leaving a significant gap in our understanding.

The significant contribution of this study lies in utilizing satellite observation data and the thermodynamics-based wet adiabatic lapse rate to estimate global mountain climate velocities, addressing the severe lack of in-situ observations. We further explore the impact of warming rates and water vapour on climate velocity differences across global mountain areas.

Besides areas experiencing rapid surface warming rates, many mountainous regions do not show significant surface warming, attributed to high humidity. However, the presence of moisture leads to a lower temperature lapse rate, which in turn accelerates climate velocity. This scenario is observed in tropical Sumatra, the maritime-influenced Brazilian Highlands, and Japan. Taiwan experiences similar conditions, indicating that given equivalent levels of warming, the climate velocity in Taiwan will be relatively higher.

A 2011 study[3] published in Science by one of the authors, I-Ching Chen, examining whether species range shifts are keeping pace with climate speeds, found a severe lag in the responses of mountain species, sparking widespread discussion. In earlier research (2009)[4], her surveys of moths on Mount Kinabalu in Borneo found that their migration speed was only about half the speed of the movement of temperature isotherms. 

The new analysis not only provides more accurate climate velocity data, but also ten times more information about biological responses. We found that in areas with lower climate velocities, organisms still have the opportunity to adapt by shifting their distributions to maintain their original temperature conditions. Thus, proactive climate mitigation remains critical for biodiversity conservation. Even in regions not listed in the 17 identified mountain areas, there might still be species at risk of not keeping up with the rate of warming, necessitating the early establishment of monitoring networks.

Q2. What do you think are the limitations of this study? Is it possible to understand the situation in Taiwan from a global perspective?

The significant value of our research lies in the estimation of variations in climate velocity in global mountain regions, which serves as a basis for biodiversity conservation efforts. However, the accurate measurement of climate velocity in the field still depends on the establishment of meteorological stations in mountainous areas. Determining the lapse rate of temperature along elevation requires multiple stations, and not just for temperature measurements - humidity and precipitation are also critical factors.

Q3. Previous research by the Taiwan Climate Change Projection and Information Platform (TCCIP) found that between 1911 and 2020, the average warming in Taiwan was greater than the global average. Could this have a greater impact on species and their migration rates in Taiwan's mountainous areas?

As noted above, it is highly likely that not only the magnitude of warming, but also high humidity environments with a lower temperature lapse rate will lead to faster climate velocities, which are expected to place greater stress on biological communities.

It is worth mentioning that Taiwan has been implementing the National Ecological Network for many years, which aims to connect natural habitats from the mountains to the sea throughout Taiwan. This policy helps to increase habitat continuity and ensure that organisms can migrate and adapt to climate change.

Q4. International reports continue to warn that delays in global mitigation will make it difficult to avoid scenarios where warming exceeds 1.5 degrees Celsius. In such a situation, what strategies or methods do we have to protect mountain biodiversity?

Maintaining viable populations and intact habitats remains a fundamental and critical approach. Beyond simply shifting distributions to adapt to climate change, healthy populations are more likely to withstand the impacts of climate variability. From a broader perspective, maintaining functional diversity also contributes to the overall resilience of ecosystems.

March 22, 2024
Dr. Chan, Wei-Ping, Postdoctoral Fellow, Rowland Institute at Harvard University

Q. Previous research by the Taiwan Climate Change Projection and Information Platform (TCCIP) found that between 1911 and 2020, the average warming in Taiwan was greater than the global average. Could this have a greater impact on species and their migration rates in Taiwan's mountainous areas?

Taiwan's mountainous regions serve as an excellent case study to validate the value of this research. Observing the surface temperature from 1970 to 2020, we found that the increase in surface temperature in Taiwan's mountains did not exceed the global average or that of other islands in the Northern Hemisphere. However, the high humidity in Taiwan's mountain areas causes the speed of the isothermal lines' shift at various elevations to be faster than the global average for mountainous areas. Although the temperature increase and the speed of isothermal line movement in Taiwan's mountains are not higher than those of other islands in the Northern Hemisphere, the impact of global warming on Taiwan's mountainous areas is evidently more severe under the same temperature increase.

By integrating the findings of this study with those of the TCCIP, we can infer more information. For instance, we see that the overall surface temperature increase in Taiwan exceeds the global average, but the increase in the mountainous areas is not significantly different from the global average. This means that Taiwan's densely populated urban and agricultural areas at lower elevations face a more severe threat from surface temperature increases. This could also explain why the Taiwanese population, mainly residing in mid to low elevation areas, feels the impact of global warming more acutely.

March 23, 2024
Prof, Lo, Min-Hui, Professor, Department of Atmospheric Sciences at National Taiwan University, Taiwan.

Previous studies [5] have shown that climate change signals are more pronounced in mountain regions, which are of significant concern for biodiversity. For instance, the increase in diurnal temperature range with elevation makes adaptation more challenging for organisms. Moreover, mountain ranges host high concentrations of endemic species that are facing anthropogenic climate changes. Therefore, understanding the impact of climate change on such phenomena is crucial for biodiversity and the scientific community, especially in mountainous regions.

This study links the rate of temperature changes with elevation to species migration rates and reports that in regions with minor temperature changes along the elevation, species can closely track these temperature shifts. However, in 17 mountain regions experiencing significant temperature changes, species may not be able to migrate in a timely manner. The study highlights the significance of climate change on biology and the need for carbon emission reduction to minimize temperature fluctuations, especially in the 17 identified mountainous areas.

The lack of observational data in mountain regions for validating theoretical models is a key issue when aiming to present robust results. Currently, the available observations are insufficient; therefore, this study employs satellite data and a theoretical model to illustrate temperature changes with elevation over the past 50 years. Satellite data may have biases due to limited spatial and temporal resolutions. A more comprehensive observation network is crucial for achieving more robust results. Hence, this study pioneers the use of the best available dataset to demonstrate how climate changes might affect mountain biodiversity, motivating the community to develop a mountain observation network in the future.

Exploring climate changes in Taiwan's mountain regions is always challenging due to the lack of available data. The results from this study may indicate the importance of maintaining a better observation network for the scientific community.

If the average warming of the surface in a country is greater than the global average, it could have a greater impact on species. Since the effects of urbanization and land-use change are critical for temperature changes, in addition to the effects of greenhouse gases. Thus, the increased temperature rate in Taiwan is higher than the global average, which may have larger impacts on Taiwan’s mountain biodiversity.

International reports continue to warn that delays in global mitigation will make it difficult to avoid scenarios where warming exceeds 1.5 degrees Celsius. Reducing anthropogenic land use change and implementing better land management and/or national park plans might be another approach to decrease the rate of temperature increase. Of course, we also need to accelerate plans to reduce greenhouse gases, aiming for a net-zero carbon emissions target before 2050.

March 23, 2024
Prof. Lin, Teng-Chiu, Professor, School of Life Science, National Taiwan Normal University

It is widely recognized that warming has major impacts on the distribution of plants and animals. Mountain region is a hotspot of global change in biology/ecology. Intuitively, we can expect that species that are adapted to low temperature will lose their current habitat if they cannot cope with climate change. Another way to cope with warming is to migrate to higher elevations that have lower temperatures.  Thus, a key issue in global change ecology is the rate of climate change relative to the rate of species migration along the elevational gradient and the rate of evolutionary change that may allow species to adapt to the new climate. For this reason, this study is of particular importance as it reports the climate velocity of climate change of 17 mountain ranges around the globe. This together with the rate of species range shifts allow us to have a good understanding if the rate of species range shifts can cope with the rate of climate change. This is important for our prediction on how climate change may reshuffle species composition and cause species extinction in the mountains. There is an increasing number of studies on species range shift of plants and animals in Taiwan and around the world. This study provides new insights or directions on future studies on the impact of climate change on species distribution or even extinction.

High spatial resolution climate data is key to more precise understanding of climate variation and shifts, especially in the mountains. Although there are general trends of climate variation, local topography including micro-topography could lead to unexpected climate spots in the mountains leading to inaccurate projections. It is not possible to have in situ weather stations all over the mountains but we do need to have more weather stations in places with rough topography. A thorough capture of the topography would guide us where we should increase in situ weather monitoring stations. However, when weather stations reach a certain number and coverage of level we may be able to build reliable models to produce accurate estimates of climate variables such as temperature and precipitation even in locations without weather stations.

In Taiwan, one of the authors of this paper, professor I-Ching Chen reported that the distribution of Lepidoptera is shifting to higher elevation, with the upper boundaries upward by an average of 152 m which was more than the retreated at their lower boundaries of 77 m in 42 years[6]. Forest ecologists also reported that the tree lines in many mountains are moving upward but at different rates possibly because the rate of climate change is different in different mountains.[7] We need to be aware of this but I do not think there is much we can do to change the fact that global climate is changing and is affecting the biosphere from genes, individuals to the entire global ecosystem. At the moment, the best we can do is to slow down the rate of climate change, via reducing the emission of greenhouse gases to allow species to cope with the rate of climate change either through range shifts or adaptation via evolution.

Q4. International reports continue to warn that delays in global mitigation will make it difficult to avoid scenarios where warming exceeds 1.5 degrees Celsius. In such a situation, what strategies or methods do we have to protect mountain biodiversity?

Besides the ongoing monitoring of biodiversity and weather patterns in the mountain regions, we need to further explore how various species can withstand environmental factors such as temperature and moisture, especially those with very narrow distribution ranges or in stable climatic conditions. Many studies also indicate that physiological tolerance determines the vulnerability of species to climate change, subsequently influencing their spatial distribution.[11][12] For example, when experiments reveal that a species has a climate niche of 0–12°C, but survival rates drop dramatically above 10°C, we can then forecast potential future habitats for this species.Therefore, strategies for their conservation often involve ex situ conservation, which entails relocating the species to suitable regions. Additionally, expanding protected zones to lower elevations and creating ecological corridors between different reserves are strategic spatial planning measures that enable mountain species to migrate to more suitable habitats. In particular, we can improve our strategies for supporting species impacted by climate change by advancing reproductive technologies. This human-assisted approach aims to safeguard the biodiversity within native mountain ecosystems. This whole effort complements our continuous monitoring of biodiversity and climate patterns in mountainous areas.

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:

• Jang, Y-S., et al. (2022) "Discontinuity of diurnal temperature range along elevated regions," Geophysical Research Letters, e2021GL097551,
• Martín, J. L., Bethencourt, J., & Cuevas-Agulló, E. (2012). Assessment of global warming on the island of Tenerife, Canary Islands (Spain). Trends in minimum, maximum and mean temperatures since 1944. Climatic Change, 114(2), 343–355.
• Pepin, N., Deng, H., Zhang, H., Zhang, F., Kang, S., & Yao, T. (2019). An Examination of Temperature Trends at High Elevations Across the Tibetan Plateau: The Use of MODIS LST to Understand Patterns of Elevation-Dependent Warming.Journal of Geophysical Research: Atmospheres, 124(11), 5738–5756.
• Shekhar, M. S., Devi, U., Dash, S. K., Singh, G. P., & Singh, A. (2018). Variability of Diurnal Temperature Range During Winter Over Western Himalaya: Range- and Altitude-Wise Study.Pure and Applied Geophysics, 175(8), 3097–3109.
• Shen, X., Liu, B., Li, G., Wu, Z., Jin, Y., Yu, P., & Zhou, D. (2014). Spatiotemporal change of diurnal temperature range and its relationship with sunshine duration and precipitation in China. Journal of Geophysical Research: Atmospheres, 119(23), 13–163.
• Thakuri, S., Dahal, S., Shrestha, D., Guyennon, N., Romano, E., Colombo, N., & Salerno, F. (2019). Elevation-dependent warming of maximum air temperature in Nepal during 1976–2015. Atmospheric Research, 228(June), 261–269.

[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.