As the Earth warms, many species are likely to disappear, often because of changing disease dynamics. Here we show that a recent mass extinction associated with pathogen outbreaks is tied to global warming. Seventeen years ago, in the mountains of Costa Rica, the Monteverde harlequin frog (Atelopus sp.) vanished along with the golden toad (Bufo periglenes). An estimated 67% of the 110 or so species of Atelopus, which are endemic to the American tropics, have met the same fate, and a pathogenic chytrid fungus (Batrachochytrium dendrobatidis) is implicated. Analysing the timing of losses in relation to changes in sea surface and air temperatures, we conclude with ‘very high confidence’ (> 99%, following the Intergovernmental Panel on Climate Change, IPCC) that large-scale warming is a key factor in the disappearances. We propose that temperatures at many highland localities are shifting towards the growth optimum of Batrachochytrium, thus encouraging outbreaks. With climate change promoting infectious disease and eroding biodiversity, the urgency of reducing greenhouse-gas concentrations is now undeniable.

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We thank T. P. Mitchell at JISAO and S. J. Worley at NCAR for help in obtaining climate data, R. A. Alford, F. Bolaños, J. P. Collins, R. O. Lawton, K. R. Lips, M. D. Mastrandrea, K. G. Murray, P. Ramírez and B. D. Santer for discussion, and the many contributors to the Atelopus database. S. H. Schneider, A. R. Blaustein and C. Parmesan commented on earlier drafts of the manuscript. The Declining Amphibian Populations Task Force and Conservation International's Critically Endangered Neotropical Species Fund provided partial funding to J.A.P. The Canada Foundation for Innovation and the Tinker Foundation helped produce the remote-sensing databases. The Research and Analysis Network for Neotropical Amphibians and the US National Science Foundation sponsored meetings that facilitated portions of the study. Author Contributions All authors after the first are listed alphabetically. J.A.P. conceived, designed and orchestrated the study, conducted most of the analyses (principally with J.A.C. and K.L.M.), formulated the chytrid-thermal-optimum hypothesis (with R.P.), and wrote the paper (with editing by J.A.C. and K.L.M.). M.R.B., L.A.C., M.P.L.F., E.L.M., A.M.-V. and S.R.R. provided key data and background information. E.L.M. compiled the Atelopus database (with B.E.Y.). P.N.F. conducted the climate simulations. G.A.S.-A. analysed the remote-sensing data. C.J.S. helped with the climate analyses and their interpretation. B.E.Y. obtained funding for meetings, provided logistics, and analysed GAA data for New World amphibians.

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Author notes

    • Pru N. Foster

    Present address: Department of Earth Sciences, University of Bristol, Wills Memorial Building, Queen's Road, Bristol, BS8 1RJ, UK


  1. Golden Toad Laboratory for Conservation, Monteverde Cloud Forest Preserve and Tropical Science Center, Puntarenas, 5655-73, Santa Elena, Costa Rica

    • J. Alan Pounds
    •  & Michael P. L. Fogden
  2. Museo de Zoología, Centro de Biodiversidad y Ambiente, Escuela de Biología, Pontificia Universidad Católica del Ecuador, Avenida 12 de Octubre 1076 y Roca, Apartado, 17-01-2184, Quito, Ecuador

    • Martín R. Bustamante
    • , Luis A. Coloma
    • , Andrés Merino-Viteri
    •  & Santiago R. Ron
  3. Department of Environmental Science, Barnard College, Columbia University, 3009 Broadway, New York, 10027, New York, USA

    • Jamie A. Consuegra
  4. Center for Climate Studies Research, University of Tokyo, Kombaba, 4-6-1, 153-8904, Meguro-ku, Tokyo, Japan

    • Pru N. Foster
  5. Laboratorio de Biogeografía, Escuela de Geografía, Facultad de Ciencias Forestales y Ambientales, Universidad de Los Andes, Apartado 116, 5101-A, Mérida, Venezuela

    • Enrique La Marca
  6. Council for International Educational Exchange, Monteverde, 5655-26, Puntarenas, Costa Rica

    • Karen L. Masters
  7. Escuela de Biología, Universidad de Costa Rica, San Pedro, Costa Rica

    • Robert Puschendorf
  8. Texas Memorial Museum and Department of Integrative Biology, University of Texas, Texas, 78712, Austin, USA

    • Santiago R. Ron
  9. Department of Earth and Atmospheric Sciences, University of Alberta, Alberta, T6G 2E3, Edmonton, Canada

    • G. Arturo Sánchez-Azofeifa
  10. Department of Geography, University of California at Santa Barbara, 3611 Ellison Hall, California, 93106, Santa Barbara, USA

    • Christopher J. Still
  11. NatureServe, Monteverde, 5655-75, Puntarenas, Costa Rica

    • Bruce E. Young


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Competing interests

Reprints and permissions information is available at The authors declare no competing financial interests.

Corresponding author

Correspondence to J. Alan Pounds.

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