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Perennial problems loom large for threatened species

This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American


Forget about climate change for a moment, the biggest threats to the world’s imperiled species are deforestation, pollution, poaching and invasive species.

Those are the findings of an analysis by the International Union for the Conservation of Nature (IUCN). Published every four years, the report examines the state of globally threatened species.

Habitat loss and pollution pose the greatest extinction risk for currently threatened amphibians, while the deadly chytrid fungus remains a lesser but still potent threat. As for threatened mammals, habitat loss and poaching may be the biggest factors wiping them off the map.


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Scientists have amassed the most detailed data yet on the world’s 1360 imperiled bird species, and the picture isn’t pretty. Climate change is number eight on the threat list, affecting about 200 species in total. More critical for these birds today are agriculture, hunting, and invasive species, like the brown tree snake that has wiped out birds on Guam.

That’s not to say that climate change isn’t a worry. About 80 percent of threatened birds, 75 percent of threatened amphibians, and 19 percent of threatened corals are considered “susceptible” to climate change in the future owing to their specialized habitat needs, physiological limitations, or other factors. The IUCN analysis also notes that between one-third and one-half of bird, coral and amphibian species not currently threatened by extinction are “susceptible” to global warming.

Habitat loss is still the main driver whose results we are seeing,” says Cagan Sekercioglu, a Stanford ornithologist who contributed data to the new report, “Climate change is building momentum . . . so it’s going to have worse and worse impacts.”

Image of fossil frog courtesy of kevinzim via Flickr

Brendan Borrell is a freelance journalist based in Brooklyn, New York. He writes for Bloomberg Businessweek, Nature, Outside, Scientific American, and many other publications, and is the co-author (with ecologist Manuel Molles) of the textbook Environment: Science, Issues, Solutions. He traveled to Brazil with the support of the Mongabay Special Reporting Initiative. Follow him on Twitter @bborrell.

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