Even as global temperatures continue to climb, the natural world appears to be changing more slowly not faster according to a major new study by researchers at Queen Mary University of London.
The research, published in Nature Communications, challenges a long-held assumption among ecologists that accelerating climate change would trigger equally rapid ecological reshuffling. Instead, scientists found that the rate at which species replace one another in local ecosystems known as species “turnover” has declined by roughly one-third since the 1970s.
Biodiversity’s Engine Is Losing Momentum
For decades, researchers believed that rising temperatures and shifting climate zones would push species out of old habitats and into new ones at increasing speed. The expectation was that ecosystems would experience faster extinctions and quicker colonization as warming intensified.
But after analyzing a global database of biodiversity surveys spanning marine, freshwater and terrestrial ecosystems over the past century, the research team discovered the opposite trend.
“We were surprised how strong the effect is,” said Professor Axel Rossberg, a co-author of the study. “Turnover rates typically declined by one third.”
Lead author Dr. Emmanuel Nwankwo compared ecosystems to a self-repairing engine that constantly replaces worn parts with new ones. “We found this engine is now grinding to a halt,” he said.
The slowdown was particularly noticeable in short-term comparisons of one to five years and was observed across diverse ecosystems from bird populations on land to organisms living on the ocean floor.
Internal Ecosystem Forces May Matter More Than Climate
The findings suggest that ecosystems are not driven solely by rising temperatures. Instead, they may be governed largely by internal biological interactions what scientists call the “multiple attractors” phase.
In this phase, species continuously replace one another due to competitive and cooperative relationships, even when environmental conditions remain stable. The process resembles a constant balancing act in which no single species dominates indefinitely.
However, the study indicates that environmental degradation and shrinking regional biodiversity may now be weakening this internal dynamism. As habitats are damaged and species disappear across broader regions, the pool of potential new colonizers shrinks. With fewer species available to move in, the pace of ecological turnover slows.
Researchers warn that this apparent stability should not be mistaken for resilience.
A slowdown in species replacement could signal that ecosystems are losing the biodiversity necessary to sustain natural renewal processes. In other words, systems that appear stable may actually be stagnating.
The findings add a new layer of concern to global climate discussions. While rising temperatures remain a primary threat, the research suggests that biodiversity loss may quietly undermine ecosystems in ways that are less visible but potentially just as dangerous.
Scientists say further monitoring will be crucial to determine whether this deceleration marks a temporary fluctuation or a long-term shift in how Earth’s ecosystems function under mounting human pressures.