Will 50 percent of vertebrates go extinct over the next century?

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This map shows extinction hot spots for vertebrates (mammals, birds, and amphibians). Brown areas and blue areas are regions of intense die-offs. It's from a massive research study published today, showing nearly one-fifth of vertebrates are threatened with extinction.

The study, conducted by team of scientists all over the world, examined 25,000 vertebrate species on the "Red List," a catalog of endangered animals. Each animal on the list is rated by how close to extinction they are, and "threatened" animals are from the three categories closest to extinction. The researchers write, "Almost one-fifth of extant vertebrate species are classified as Threatened, ranging from 13% of birds to 41% of amphibians." One of the reasons that amphibians are in more danger is that conservation efforts rarely focus on them. Perhaps frogs are too slimy to rake in the eco donations that fuzzy seals and cute owls get?

According to a release about the study:

On average, 52 species of mammals, birds and amphibians move one category closer to extinction each year. The tropics, especially Southeast Asia, are home to the highest concentrations of Threatened animals, and the situation for amphibians is particularly serious. Most declines are reversible, but in 16 percent of cases they have led to extinction.


Another paper related to this study extrapolates what these numbers might mean for the future of biodiversity.

In this map, you can see patterns of biodiversity deterioration and improvement over time. Areas in purple are deteriorating, with more species joining the Red List (the darker the purple, the worse the net deterioration). Areas in green are improving. The researchers note that the deterioration is outpacing improvements.

Environmental scientist Paul Leadley also conducted a survey of research into future scenarios for biodiversity on Earth. He said:

There is no question that business-as-usual development pathways will lead to catastrophic biodiversity loss. Even optimistic scenarios for this century consistently predict extinctions and shrinking populations of many species.


So things are only going to get worse.

But predictions like this aren't easy to make accurately, partly because we're at a point in history when many different outcomes are possible for threatened vertebrates. Depending on whether humans slow deforestation and pollution, extinction rates over the next century could remain at the current rate of less than 1%, or grow to more than 50%. Leadly added that another area of uncertainty is species ecology. How many animals have to die before there is a domino effect that leads to many more species extinctions? We simply can't say for sure.


What is certain is that an enormous number of mammals, birds, and amphibians may not survive the next 100 years. Scientists also agree that humans can prevent the mass extinction that some scenarios predict. It's just a question of whether we'll do what's needed in time to save our furry, slimy, and feathered friends.

Read the full scientific papers via Science: The Impact of Conservation on the Status of the World's Vertebrates and Scenarios for Global Biodiversity in the 21st Century