LONDON — Many ecologists hypothesise that, as global warming accelerates, change in nature must speed up. They assume that as temperatures rise and climatic zones shift, species will face local extinction and colonize new habitats at an ever-increasing rate, leading to a rapid reshuffling of ecological communities.
A new study by researchers at Queen Mary University of London (QMUL) and published in Nature Communications shows this is emphatically not the case.
The researchers analyzed a massive database of biodiversity surveys, spanning marine, freshwater, and terrestrial ecosystems over the last century. The evidence showed that not only had the “turnover” of species in local habitats not sped up, but instead, it had significantly slowed down.
Dr Emmanuel 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 Dominance of Intrinsic Dynamics
The study focused on the period since the 1970s, a time marked by a documented acceleration in global surface temperatures and environmental shifts. The researchers compared species turnover rates—the speed at which species replace each other—before and after this climate acceleration.
Contrary to the expectation that external climate forces would drive faster change, the data revealed that turnover over 1-5 year periods tended to become slower. This slowdown was consistent across diverse environments such as terrestrial bird communities or the seabed.
Professor Axel Rossberg, co-author of the study at Queen Mary University of London, said: “We were surprised how strong the effect is. Turnover rates typically declined by one third.”
To explain this counter-intuitive finding, the researchers point to the fundamental way ecosystems organize themselves. The study suggests that the communities analyzed are not merely reacting passively to external climate drivers. Instead, they appear to be operating in a state known as the “Multiple Attractors” phase that was predicted by theoretical physicist Guy Bunin in 2017. This multiple attractors phase is a state where species continuously replace one another due to internal interactions—like in a giant, unending game of rock-paper-scissors—even without environmental changes. The new study now provides strong empirical evidence that this multiple attractors phase exists and actually dominates nature.
A Worrying Sign of Degradation
If ecosystems are driven by these intrinsic dynamics, why is the turnover slowing down? The authors argue that the observed deceleration is a side effect of environmental degradation and the shrinking of regional species pools.
In a healthy “Multiple Attractors phase” ecosystem, a large pool of potential colonizers keeps the revolving door of species turnover moving. However, as human activity degrades habitats and reduces these regional pools, the number of potential colonizers drops. This slows the pace at which species replace one another.
Dr Nwankwo said: “In other research we are seeing clear indications that human impacts cause the slowing of turnover. It is worrying.”
The findings suggest that a lack of change in local species composition should not be mistaken for stability or ecosystem health. Instead, the widespread slowdown may indicate that the internal engines of biodiversity are losing momentum due to the depletion of regional life.
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