Has the Earth’s sixth mass extinction already arrived?

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Abstract

Palaeontologists characterize mass extinctions as times when the Earth loses more than three-quarters of its species in a geologically short interval, as has happened only five times in the past 540 million years or so. Biologists now suggest that a sixth mass extinction may be under way, given the known species losses over the past few centuries and millennia. Here we review how differences between fossil and modern data and the addition of recently available palaeontological information influence our understanding of the current extinction crisis. Our results confirm that current extinction rates are higher than would be expected from the fossil record, highlighting the need for effective conservation measures.

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Figure 1: Relationship between extinction rates and the time interval over which the rates were calculated, for mammals.
Figure 2: Extinction magnitudes of IUCN-assessed taxa 6 in comparison to the 75% mass-extinction benchmark.
Figure 3: Extinction rate versus extinction magnitude.

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Acknowledgements

S. Beissinger, P. Ehrlich, E. Hadly, A. Hubbe, D. Jablonski, S. Pimm and D. Wake provided constructive comments. Paleobiology Database data were contributed by M. Carrano, J. Alroy, M. Uhen, R. Butler, J. Mueller, L. van den Hoek Ostende, J. Head, E. Fara, D. Croft, W. Clyde, K. Behrensmeyer, J. Hunter, R. Whatley and W. Kiessling. The work was funded in part by NSF grants EAR-0720387 (to A.D.B.) and DEB-0919451 (supporting N.M.). This is University of California Museum of Paleontology Contribution 2024.

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All authors participated in literature review and contributed to discussions that resulted in this paper. A.D.B. planned the project, analysed and interpreted data, and wrote the paper. N.M. and S.T. performed key data analyses and interpretation relating to rate comparisons. G.O.U.W., B.S. and E.L.L. assembled critical data. T.B.Q. and C.M. provided data, analyses and ideas relating to diversity dynamics and rate-magnitude comparisons. J.L.M. helped produce figures and with N.M., S.T., G.O.U.W., B.S., T.B.Q., C.M., K.C.M., B.M. and E.A.F. contributed to finalizing the text.

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Correspondence to Anthony D. Barnosky.

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Barnosky, A., Matzke, N., Tomiya, S. et al. Has the Earth’s sixth mass extinction already arrived?. Nature 471, 51–57 (2011). https://doi.org/10.1038/nature09678

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