Climate change: which animals are most threatened with extinction?

Human-caused climate change is accelerating rapidly and has already had noticeable impacts on biodiversity. Despite its crucial importance for future projections, understanding of the underlying mechanisms that drive extinction under climatic influence remains limited. A newly published study in the journal Science presents an approach that explores the interaction between species traits and climate change in shaping extinction risk for marine invertebrates throughout the Phanerozoic, the geological interval of “visible” life. This investigation shows which traits most strongly influence extinction risk in different species.

Led by Cooper Malanoski and Erin Saupe of the University of Oxford, the research team analyzed more than 290,000 fossils of marine invertebrates from the past 485 million years, including snails, shellfish, and sea urchins. The aim was to identify factors that influence extinction resistance. The scientists created a dataset containing key factors that have previously been insufficiently explored, such as a species’ preferred temperature range. These factors were integrated into climate simulation data to develop a model that better explains the significance of different influences on extinction risk during climate change.

Critical factors: range, habitat, and body size

The results suggest that species exposed to more intense climate change are more likely to be threatened with extinction. In particular, species that experienced temperature fluctuations of 7 degrees Celsius or more over longer periods were affected. The analyses also show that organisms living in extreme climate zones such as the polar regions are disproportionately at risk of extinction. Animals whose habitats are strongly temperature-dependent, especially in regions with temperatures below 15 degrees Celsius, are particularly vulnerable to extinction risk under climatic change.

In the study, range size proved to be the most important factor for extinction risk: marine invertebrates with larger geographic ranges were significantly less threatened with extinction than species with smaller ranges. Body size also played a role, with smaller species being more vulnerable to extinction than larger ones.

All the examined factors acted cumulatively on extinction risk. This means that species with both a small range and a limited preferred temperature range were even more vulnerable to extinction than species possessing only one of these traits. The model suggests that species with restricted thermal ranges of less than 15 degrees Celsius, located at the poles or near the equator, are likely to be most threatened with extinction.

The current study highlights the serious consequences of human-caused climate change for biodiversity. It suggests that numerous species are already being pushed to the brink of extinction or beyond it. The insights from this investigation provide valuable clues for identifying the animals most at risk and developing conservation strategies for them.

Case study: sea-level rise and extinction on Bramble Cay

A more recent example of the link between anthropogenic climate change and extinction is the Bramble Cay melomys, which disappeared between 2009 and 2011. This rodent species lived exclusively on the small, uninhabited Australian island of Bramble Cay, whose highest point rises only three meters above sea level. The climate-driven rise in sea level since the 1990s has had immense effects on the island. Frequent inundation and tropical cyclones led to the loss of almost all of the island’s vegetation, the shrinking of the permanently dry land area, and ultimately the extinction of the Bramble Cay melomys.