ECOLOGY
Extinction risks from climate change By Janneke Hille Ris Lambers
PHOTO: BRAD MITCHELL/ALAMY
B
iologists worry that the rapid rates of warming projected for the planet (1) will doom many species to extinction. Species could face extinction with climate change if climatically suitable habitat disappears or is made inaccessible by geographic barriers or species’ inability to disperse (see the figure, panels A to E). Previous studies have provided region- or taxon-specific estimates of biodiversity loss with climate change that range from 0% to 54%, making it difficult to assess the seriousness of this problem. On page 571 of this issue, Urban (2) provides a synthetic and sobering estimate of climate change–induced biodiversity loss by applying a model-averaging approach to 131 of these studies. The result is a projection that up to one-sixth of all species may go extinct if we follow “business as usual” trajectories of carbon emissions. By quantitatively assessing how extinction risk depends on model assumptions, Urban’s study provides insight into factors that increase biodiversity loss with climate change. Surprisingly, the modeling approaches used in the studies that Urban surveyed did not have the largest effect on estimates of extinction risk, despite substantial methodological differences. Instead, the magnitude of future climate change was the most important predictor of extinction risk, with increased warming resulting in greater biodiversity loss. What is worrying, given the current anthropogenic carbon emissions trajectory, is that biodiversity loss is predicted to accelerate with greater climate change. Geography also plays a role, with higher extinction risks projected for Australia, New Zealand, and South America—regions with high numbers of endemic species (that is, species with
Department of Biology, University of Washington, Seattle, WA 98195, USA. E-mail: [email protected]
Complex threats. In addition to climate change, habitat transformation, invasive species, and pathogens also threaten amphibians like the Cascades frog, Rana cascadae (8, 11).
narrow distribution ranges) that face disappearing habitats or geographic barriers to migration (see the figure, panels C and D). Urban also found higher biodiversity loss for studies focusing on endemic species, but few differences among taxonomic groups (such as birds and amphibians). Projections of geographic and trait-based variation in extinction risk such as these are essential for targeted conservation efforts (3). The study also highlights critical uncertainties in our understanding of how climate change drives extinction. For example,
if suitable habitat disappears entirely with climate change, extinction seems inevitable. However, what if climatically suitable habitats still exist but shrink in size or quality (see the figure, panel C) (4)? Biologists believe extinction will occur before suitable habitats disappear, but they lack information on species-specific threshold habitat sizes for extinction. Similarly, what happens if species cannot reach a newly suitable habitat (see the figure, panels D and E) (5)? Biologists assume that slow-moving organisms will have trouble “keeping up”
A Species distributions with climate
B Distribution shifts with climate change Previously suitable Newly suitable Dispersal Mortality
Climatically suitable
Equator
Latitude
Pole
C Declining habitat size
Equator
Latitude
Equator
Latitude
Pole
Latitude
Mountain Pole
D Migration barrier
Pole
Equator
F Critical unknowns
E Limited dispersal ability
Global change
? Behavior or adaptation? Other species?
Equator
Latitude
Pole
Equator
Latitude
Pole
Move, adapt, or perish. Species distributions are generally determined by climate (A). They track climate change (red arrows) if populations can disperse and establish in newly suitable habitats, and disappear where climate has become unsuitable (B). Species may face extinction if habitat sizes shrink (for example, at the poles or at mountaintops) (C), or if migration barriers (D) or limited dispersal ability (E) prevent them from reaching newly suitable habitat. The ability of species to adapt (or modify their behavior), species interactions, and other global change stressors represent key uncertainties (F) that affect our ability to predict biodiversity loss with climate change.
SCIENCE sciencemag.org
1 MAY 2015 • VOL 348 ISSUE 6234
Published by AAAS
501
Downloaded from www.sciencemag.org on May 1, 2015
How will climate change affect global biodiversity?
INSIGHTS | P E R S P E C T I V E S
with climate change, but there is sparse information on just how rapidly most species can migrate. Urban’s study illustrates that our uncertainty about these processes matters greatly, with assumptions about dispersal and threshold habitat sizes for extinction strongly influencing projected biodiversity loss. The biggest unknowns about biodiversity loss with climate change arise from processes that are never (or only rarely) included in the predictive models that Urban surveyed. For example, can adaptation or behavior buffer species from the negative impacts of climate change? Given that extinction is not instantaneous, how rapidly will biodiversity be lost (6)? Will other global change factors, such as invasive species, exacerbate climate change impacts (see the photo) (7, 8)? Will species interactions magnify biodiversity loss from climate change (9) or, alternatively, buffer species from negative impacts of climate change (10)? These are challenging questions that biologists are only just beginning to address when considering climate change impacts on biodiversity (7). Midway through what could well turn out to be the warmest decade in the past 170 years (1), Urban’s study joins many others suggesting that climate change will have enormous impacts on the organisms with which we share our planet. Many uncertainties remain, and biologists will continue to improve forecasts of biodiversity loss with climate change by gathering additional data and incorporating additional complexities into models. However, we should not wait for these forecasts before taking action, preferentially by curbing emissions (1) but also by devising strategies to mitigate the negative impacts of climate change on biodiversity (3, 7). If we do not, it is clear that we will soon be able to directly observe the impacts of climate change on biodiversity. ■
ECOLOGY
Human-wildlife conflicts in a crowded airspace How can the ecological consequences of the increasing use of airspace by humans be minimized? By Sergio A. Lambertucci,1 Emily L. C. Shepard,2 Rory P. Wilson2
O
ver the past century, humans have increasingly used the airspace for purposes such as transportation, energy generation, and surveillance. Conflict with wildlife may arise from buildings, turbines, power lines, and antennae that project into space and from flying objects such as aircrafts, helicopters, and unmanned aerial vehicles (UAVs, or drones) (see the figure) (1–3). The resulting collision and disturbance risks profoundly affect species ecology and conservation (1, 4, 5). Yet, aerial interactions between humans and wildlife are often neglected when considering the ecological consequences of human activities. Airspace is needed for key ecological processes and ecosystem services. For instance, billions of individuals from different taxa migrate every year, modulating patterns of biodiversity via the transport of nutrients, energy, toxicants, propagules, and parasites (6). Therefore maintaining the diversity,
abundance and movement of aerial organisms is vital for a range of ecosystem-level processes. Most flying animals operate within a hundred meters from the ground, with abundance decreasing with height (7). Animals thus move at heights relevant to most human-made structures and moving objects (see the figure). Buildings, power lines, antennae, and wind farms cause millions of animal deaths via collisions annually, both over land and water, and have increased the extinction risk of several vertebrate species (1, 5). Collisions with flying aircraft mostly occur at altitudes of 60 to 120 m during takeoff and landing, although occasional collisions occur at cruising altitudes (8). To date, more than two hundred people have been killed globally and thousands of aircraft damaged as a result of bird collisions (2). In the United States, the cost of bird strikes exceeds $900 million a year, with strikes increasing six-fold over the past two decades (11,315 recorded strikes in 2013) (2). There are also less obvious effects. For example, buildings and wind farms influence
1. Summary for Policymakers, in Climate Change 2013: The Physical Science Basis. Contribution of the Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, T. F. Stocker et al., Eds. (Cambridge Univ. Press, Cambridge, 2013). 2. M. C. Urban, Science 348, 571 (2015). 3. O. Hoegh-Guldberg et al., Science 321, 345 (2008). 4. S. C. Amstrup et al., Nature 468, 955 (2010). 5. C. A. Schloss, T. A. Nuñez, J. J. Lawler, Proc. Natl. Acad. Sci. U.S.A. 109, 8606 (2012). 6. S. T. Jackson, D. F. Sax, Trends Ecol. Evol. 25, 153 (2010). 7. J. J. Lawler, A. S. Ruesch, J. D. Olden, B. H. McRae, Ecol. Lett. 16, 1014 (2013). 8. C. Hof, M. B. Araújo, W. Jetz, C. Rahbek, Nature 480, 516 (2011). 9. R. K. Colwell, R. R. Dunn, N. C. Harris, Annu. Rev. Ecol. Evol. Syst. 43, 183 (2012). 10. R. M. Pateman, J. K. Hill, D. B. Roy, R. Fox, C. D. Thomas, Science 336, 1028 (2012). 11. M. E. Ryan, W. J. Palen, M. J. Adams, R. M. Rochefort, Front. Ecol. Environ. 12, 232 (2014).
PHOTO: MARTY MELVILLE/AFP/GETTY IMAGES
REFERENCES
A seagull sweeps at a Sky TV drone.
10.1126/science.aab2057
502
sciencemag.org SCIENCE
1 MAY 2015 • VOL 348 ISSUE 6234
Published by AAAS
Extinction risks from climate change Janneke Hille Ris Lambers Science 348, 501 (2015); DOI: 10.1126/science.aab2057
This copy is for your personal, non-commercial use only.
Permission to republish or repurpose articles or portions of articles can be obtained by following the guidelines here. The following resources related to this article are available online at www.sciencemag.org (this information is current as of April 30, 2015 ): Updated information and services, including high-resolution figures, can be found in the online version of this article at: http://www.sciencemag.org/content/348/6234/501.full.html A list of selected additional articles on the Science Web sites related to this article can be found at: http://www.sciencemag.org/content/348/6234/501.full.html#related This article cites 10 articles, 4 of which can be accessed free: http://www.sciencemag.org/content/348/6234/501.full.html#ref-list-1 This article appears in the following subject collections: Ecology http://www.sciencemag.org/cgi/collection/ecology
Science (print ISSN 0036-8075; online ISSN 1095-9203) is published weekly, except the last week in December, by the American Association for the Advancement of Science, 1200 New York Avenue NW, Washington, DC 20005. Copyright 2015 by the American Association for the Advancement of Science; all rights reserved. The title Science is a registered trademark of AAAS.
Downloaded from www.sciencemag.org on May 1, 2015
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Extinction risks from climate change By Janneke Hille Ris Lambers
PHOTO: BRAD MITCHELL/ALAMY
B
iologists worry that the rapid rates of warming projected for the planet (1) will doom many species to extinction. Species could face extinction with climate change if climatically suitable habitat disappears or is made inaccessible by geographic barriers or species’ inability to disperse (see the figure, panels A to E). Previous studies have provided region- or taxon-specific estimates of biodiversity loss with climate change that range from 0% to 54%, making it difficult to assess the seriousness of this problem. On page 571 of this issue, Urban (2) provides a synthetic and sobering estimate of climate change–induced biodiversity loss by applying a model-averaging approach to 131 of these studies. The result is a projection that up to one-sixth of all species may go extinct if we follow “business as usual” trajectories of carbon emissions. By quantitatively assessing how extinction risk depends on model assumptions, Urban’s study provides insight into factors that increase biodiversity loss with climate change. Surprisingly, the modeling approaches used in the studies that Urban surveyed did not have the largest effect on estimates of extinction risk, despite substantial methodological differences. Instead, the magnitude of future climate change was the most important predictor of extinction risk, with increased warming resulting in greater biodiversity loss. What is worrying, given the current anthropogenic carbon emissions trajectory, is that biodiversity loss is predicted to accelerate with greater climate change. Geography also plays a role, with higher extinction risks projected for Australia, New Zealand, and South America—regions with high numbers of endemic species (that is, species with
Department of Biology, University of Washington, Seattle, WA 98195, USA. E-mail: [email protected]
Complex threats. In addition to climate change, habitat transformation, invasive species, and pathogens also threaten amphibians like the Cascades frog, Rana cascadae (8, 11).
narrow distribution ranges) that face disappearing habitats or geographic barriers to migration (see the figure, panels C and D). Urban also found higher biodiversity loss for studies focusing on endemic species, but few differences among taxonomic groups (such as birds and amphibians). Projections of geographic and trait-based variation in extinction risk such as these are essential for targeted conservation efforts (3). The study also highlights critical uncertainties in our understanding of how climate change drives extinction. For example,
if suitable habitat disappears entirely with climate change, extinction seems inevitable. However, what if climatically suitable habitats still exist but shrink in size or quality (see the figure, panel C) (4)? Biologists believe extinction will occur before suitable habitats disappear, but they lack information on species-specific threshold habitat sizes for extinction. Similarly, what happens if species cannot reach a newly suitable habitat (see the figure, panels D and E) (5)? Biologists assume that slow-moving organisms will have trouble “keeping up”
A Species distributions with climate
B Distribution shifts with climate change Previously suitable Newly suitable Dispersal Mortality
Climatically suitable
Equator
Latitude
Pole
C Declining habitat size
Equator
Latitude
Equator
Latitude
Pole
Latitude
Mountain Pole
D Migration barrier
Pole
Equator
F Critical unknowns
E Limited dispersal ability
Global change
? Behavior or adaptation? Other species?
Equator
Latitude
Pole
Equator
Latitude
Pole
Move, adapt, or perish. Species distributions are generally determined by climate (A). They track climate change (red arrows) if populations can disperse and establish in newly suitable habitats, and disappear where climate has become unsuitable (B). Species may face extinction if habitat sizes shrink (for example, at the poles or at mountaintops) (C), or if migration barriers (D) or limited dispersal ability (E) prevent them from reaching newly suitable habitat. The ability of species to adapt (or modify their behavior), species interactions, and other global change stressors represent key uncertainties (F) that affect our ability to predict biodiversity loss with climate change.
SCIENCE sciencemag.org
1 MAY 2015 • VOL 348 ISSUE 6234
Published by AAAS
501
Downloaded from www.sciencemag.org on May 1, 2015
How will climate change affect global biodiversity?
INSIGHTS | P E R S P E C T I V E S
with climate change, but there is sparse information on just how rapidly most species can migrate. Urban’s study illustrates that our uncertainty about these processes matters greatly, with assumptions about dispersal and threshold habitat sizes for extinction strongly influencing projected biodiversity loss. The biggest unknowns about biodiversity loss with climate change arise from processes that are never (or only rarely) included in the predictive models that Urban surveyed. For example, can adaptation or behavior buffer species from the negative impacts of climate change? Given that extinction is not instantaneous, how rapidly will biodiversity be lost (6)? Will other global change factors, such as invasive species, exacerbate climate change impacts (see the photo) (7, 8)? Will species interactions magnify biodiversity loss from climate change (9) or, alternatively, buffer species from negative impacts of climate change (10)? These are challenging questions that biologists are only just beginning to address when considering climate change impacts on biodiversity (7). Midway through what could well turn out to be the warmest decade in the past 170 years (1), Urban’s study joins many others suggesting that climate change will have enormous impacts on the organisms with which we share our planet. Many uncertainties remain, and biologists will continue to improve forecasts of biodiversity loss with climate change by gathering additional data and incorporating additional complexities into models. However, we should not wait for these forecasts before taking action, preferentially by curbing emissions (1) but also by devising strategies to mitigate the negative impacts of climate change on biodiversity (3, 7). If we do not, it is clear that we will soon be able to directly observe the impacts of climate change on biodiversity. ■
ECOLOGY
Human-wildlife conflicts in a crowded airspace How can the ecological consequences of the increasing use of airspace by humans be minimized? By Sergio A. Lambertucci,1 Emily L. C. Shepard,2 Rory P. Wilson2
O
ver the past century, humans have increasingly used the airspace for purposes such as transportation, energy generation, and surveillance. Conflict with wildlife may arise from buildings, turbines, power lines, and antennae that project into space and from flying objects such as aircrafts, helicopters, and unmanned aerial vehicles (UAVs, or drones) (see the figure) (1–3). The resulting collision and disturbance risks profoundly affect species ecology and conservation (1, 4, 5). Yet, aerial interactions between humans and wildlife are often neglected when considering the ecological consequences of human activities. Airspace is needed for key ecological processes and ecosystem services. For instance, billions of individuals from different taxa migrate every year, modulating patterns of biodiversity via the transport of nutrients, energy, toxicants, propagules, and parasites (6). Therefore maintaining the diversity,
abundance and movement of aerial organisms is vital for a range of ecosystem-level processes. Most flying animals operate within a hundred meters from the ground, with abundance decreasing with height (7). Animals thus move at heights relevant to most human-made structures and moving objects (see the figure). Buildings, power lines, antennae, and wind farms cause millions of animal deaths via collisions annually, both over land and water, and have increased the extinction risk of several vertebrate species (1, 5). Collisions with flying aircraft mostly occur at altitudes of 60 to 120 m during takeoff and landing, although occasional collisions occur at cruising altitudes (8). To date, more than two hundred people have been killed globally and thousands of aircraft damaged as a result of bird collisions (2). In the United States, the cost of bird strikes exceeds $900 million a year, with strikes increasing six-fold over the past two decades (11,315 recorded strikes in 2013) (2). There are also less obvious effects. For example, buildings and wind farms influence
1. Summary for Policymakers, in Climate Change 2013: The Physical Science Basis. Contribution of the Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, T. F. Stocker et al., Eds. (Cambridge Univ. Press, Cambridge, 2013). 2. M. C. Urban, Science 348, 571 (2015). 3. O. Hoegh-Guldberg et al., Science 321, 345 (2008). 4. S. C. Amstrup et al., Nature 468, 955 (2010). 5. C. A. Schloss, T. A. Nuñez, J. J. Lawler, Proc. Natl. Acad. Sci. U.S.A. 109, 8606 (2012). 6. S. T. Jackson, D. F. Sax, Trends Ecol. Evol. 25, 153 (2010). 7. J. J. Lawler, A. S. Ruesch, J. D. Olden, B. H. McRae, Ecol. Lett. 16, 1014 (2013). 8. C. Hof, M. B. Araújo, W. Jetz, C. Rahbek, Nature 480, 516 (2011). 9. R. K. Colwell, R. R. Dunn, N. C. Harris, Annu. Rev. Ecol. Evol. Syst. 43, 183 (2012). 10. R. M. Pateman, J. K. Hill, D. B. Roy, R. Fox, C. D. Thomas, Science 336, 1028 (2012). 11. M. E. Ryan, W. J. Palen, M. J. Adams, R. M. Rochefort, Front. Ecol. Environ. 12, 232 (2014).
PHOTO: MARTY MELVILLE/AFP/GETTY IMAGES
REFERENCES
A seagull sweeps at a Sky TV drone.
10.1126/science.aab2057
502
sciencemag.org SCIENCE
1 MAY 2015 • VOL 348 ISSUE 6234
Published by AAAS
Extinction risks from climate change Janneke Hille Ris Lambers Science 348, 501 (2015); DOI: 10.1126/science.aab2057
This copy is for your personal, non-commercial use only.
Permission to republish or repurpose articles or portions of articles can be obtained by following the guidelines here. The following resources related to this article are available online at www.sciencemag.org (this information is current as of April 30, 2015 ): Updated information and services, including high-resolution figures, can be found in the online version of this article at: http://www.sciencemag.org/content/348/6234/501.full.html A list of selected additional articles on the Science Web sites related to this article can be found at: http://www.sciencemag.org/content/348/6234/501.full.html#related This article cites 10 articles, 4 of which can be accessed free: http://www.sciencemag.org/content/348/6234/501.full.html#ref-list-1 This article appears in the following subject collections: Ecology http://www.sciencemag.org/cgi/collection/ecology
Science (print ISSN 0036-8075; online ISSN 1095-9203) is published weekly, except the last week in December, by the American Association for the Advancement of Science, 1200 New York Avenue NW, Washington, DC 20005. Copyright 2015 by the American Association for the Advancement of Science; all rights reserved. The title Science is a registered trademark of AAAS.
Downloaded from www.sciencemag.org on May 1, 2015
If you wish to distribute this article to others, you can order high-quality copies for your colleagues, clients, or customers by clicking here.
