Even though climate change is speeding up, ecosystems are changing more slowly, not faster. Short-term species turnover has slowed in many ecosystems over the past century despite accelerating climate change according to a new study published in Nature Communications on February 3, 2026.
‘Turnover’ is defined as the rate at which species exit and are replaced by others within ecological communities.
Researchers from Queen Mary University, London, UK analysed biodiversity surveys from land, freshwater, and marine habitats over the last century. They found that species turnover over short time intervals (1-5 years) has decelerated in significantly more communities during the last 100 years than it has accelerated, typically by one-third.
The recent changes in species composition are often driven by internal ecosystem dynamics rather than climate change, suggests the study. Researchers say that the observed deceleration is a side effect of environmental degradation and the shrinking of regional species pools.
To test the generality of the results across community types, researchers repeated the analysis separately for the four types that contribute most to the overall result: benthos, fish, birds, and the mixed communities.
The observed slowdown replicated independently for mixed, bird, and benthic communities. For fish communities, there was no consistent signal, presumably reflecting that most underlying data are surveys of exploited fish communities where fisheries management disrupts natural community dynamics.
Axel Rossberg, co-author of the study said, “We were surprised at how strong the effect is. Turnover rates typically declined by one third.”
Many researchers expect either an acceleration of turnover with accelerating climate change or constant turnover if intrinsic mechanisms dominate. It is assumed that as temperatures rise and climatic zones shift, species would face local extinction, and new habitats would be colonised at an ever-increasing rate. But the study showed that this was not the case.
Healthy ecosystems maintain a large reservoir of potential colonising species that ensures continuous species turnover that in turn promote resilience and adaptability. However, anthropogenic impacts such as habitat destruction, pollution, and fragmentation have drastically diminished the species pools.
The loss of turnover momentum could reduce ecosystems’ capacity to cope with future climate fluctuations, amplifying the risk of abrupt ecological regime shifts. Scientists warned that the slowdown is not a sign of stability, but a sign of environmental degradation and shrinking species pools. Nature’s ability to self-repair could be weakening.
Emmanuel C Nwankwo, lead author of the study, explained, “Nature functions like a self-repairing engine, constantly swapping out old parts for new ones. But we found this engine is now grinding to a halt.”
The study focused on the period since the 1970s. The researchers compared turnover rates in BioTIME database of time series of community composition for the periods up to and since a given breakpoint year — hypothesised to mark the acceleration of environmental shifts.