February 2026

Biodiversity loss is an ongoing challenge, but some of the language we use to describe it may be on shakier ground than we realize. Are we really living through a “sixth mass extinction”? What does that phrase technically imply, and how well is it supported by the data? And what about climate change: how much species-level extinction can credibly be attributed to warming so far, and how do you attribute causes when multiple threats interact?

To explore these questions, I spoke with John Wiens, an ecologist at the University of Arizona whose work focuses on extinction rates and climate-driven range losses. We discuss what the evidence suggests about acceleration (or the lack thereof) in extinction in recent decades, why documented extinctions have been concentrated on islands and in freshwater systems, and how climate change is expected to reshape extinction risk through mechanisms like heat extremes, shifting range limits, and disease dynamics. The thread running through it all is credibility and ambition: how to communicate urgency without overclaiming, and why a stronger conservation goal is not “avoiding a mass extinction,” but preventing extinctions wherever we still can.

Links to resources

• Future threats to biodiversity and pathways to their prevention - The 2017 Tilman et al. article that John referred to in our discussion

• Unpacking the extinction crisis: rates, patterns and causes of recent extinctions in plants and animals - A 2025 article by John and colleagues

Links to resources

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