How many species will Earth lose to climate change?

Abstract

Climate change may be an important threat to global biodiversity, potentially leading to the extinction of numerous species. But how many? There have been various attempts to answer this question, sometimes yielding strikingly different estimates. Here, we review these estimates, assess their disagreements and methodology, and explore how we might reach better estimates. Large‐scale studies have estimated the extinction of ~1% of sampled species up to ~70%, even when using the same approach (species distribution models; SDMs). Nevertheless, worst‐case estimates often converge near 20%–30% species loss, and many differences shrink when using similar assumptions. We perform a new review of recent SDM studies, which show ~17% loss of species to climate change under worst‐case scenarios. However, this review shows that many SDM studies are biased by excluding the most vulnerable species (those known from few localities), which may lead to underestimating global species loss. Conversely, our analyses of recent climate change responses show that a fundamental assumption of SDM studies, that species' climatic niches do not change over time, may be frequently violated. For example, we find mean rates of positive thermal niche change across species of ~0.02°C/year. Yet, these rates may still be slower than projected climate change by ~3–4 fold. Finally, we explore how global extinction levels can be estimated by combining group‐specific estimates of species loss with recent group‐specific projections of global species richness (including cryptic insect species). These preliminary estimates tentatively forecast climate‐related extinction of 14%–32% of macroscopic species in the next ~50 years, potentially including 3–6 million (or more) animal and plant species, even under intermediate climate change scenarios.

Rising Temperatures, Falling Leaves: Predicting the Fate of Cyprus’s Endemic Oak under Climate and Land Use Change

“…Climate and land-use alterations will significantly threaten plant diversity in the ensuing decades [ 1 ], markedly influencing species abundances, phenologies, and community composition, with expectations of escalating impacts [ 2 ], potentially leading to the loss of up to 31% of known plant species [ 3 ]. The Mediterranean Basin, recognised both as a global biodiversity hotspot [ 4 ] and a climate change hotspot [ 5 , 6 ], epitomises these challenges.…”

The Influence of Climate Change on the Distribution of Hibiscus mutabilis in China: MaxEnt Model-Based Prediction

“…The application of species distribution models (SDMs) has become a pivotal tool in the study of ecology and conservation biology [6,7]. Among these models, the MaxEnt model, developed by Phillips, is a spatial distribution model at the geographic scale based on the maximum entropy theory [8].…”

Predict the effects of climate change by studying the effects of climate change

“…These effects include warm-edge local extinctions that were observed in almost half of all species surveyed over time (Wiens, 2016). It is now possible to combine data on these local extinctions with data for the same species on niche shifts and dispersal, and then use these analyses to predict global patterns of climaterelated extinction in the future (Román-Palacios & Wiens, 2020; Wiens & Zelinka, 2024). Much of these data on climate-related local extinctions were from surveys separated by many decades, a potentially important limiting factor.…”