Estimating the extinction risk from climate change

To learn how Earth’s species go extinct, scientists have often focused on organisms’ intrinsic traits—body size or the geographic range of a habitat, for example. Yet some of the largest mass extinctions in the geologic past have also been connected to climate change. Some previous studies have assessed how climate change can reduce biodiversity from a planetary perspective.

To disentangle various causes of extinction, it would help to understand interactions between extrinsic and intrinsic factors from the geologic past and apply them to the modern era. Now Cooper Malanoski and Erin Saupe of the University of Oxford and their colleagues have analyzed extinction risk at a more fine-grained level, for groups of species in various locations. By combining paleontological observations and climate simulations that cover nearly half a billion years, the researchers have found that various traits and the magnitude of climate change are critical to predicting extinction.

The researchers analyzed marine invertebrates, because they have been continuously preserved in the fossil record, making them the ideal model organisms for studying extinction dynamics over geologic time scales. The Phanerozoic eon, which began about 540 million years ago, has witnessed multiple extinction events, some associated with large swings in global temperature.

Using observations of more than 9000 extinct and living genera—archived at a public database of paleontology data—and paleoclimate simulations of ocean temperature, they made a data set of several previously identified predictors of a species’ extinction risk. It includes, among other traits, organisms’ geographic range, body size, preferred environmental temperature, and overall range of temperatures occupied.

All the traits that were studied are statistically significant for predicting the last occurrence of a genus in the fossil record. Geographic range, in particular, was the strongest contributor. The traits also interact with each other, which highlights the complexity of how organisms may respond to extinction pressure. The effects of traits, however, weren’t sufficient to explain the total observed extinction: The magnitude of climate change, the researchers found, independently contributes to extinction risk. That may mean that, if the magnitude of modern anthropogenic climate change is large enough, marine life may be threatened by extinction regardless of the traits that they have. (C. M. Malanoski et al., Science 383, 1130, 2024 .)