A theoretical physicist once predicted that ecosystems might behave like perpetual games of rock-paper-scissors, with species endlessly cycling through dominance patterns that never settle into equilibrium. In 2017, Guy Bunin published this idea as an abstract mathematical possibility. Now, in one of ecology's stranger plot twists, that theory has helped explain why nature's reshuffling is grinding to a halt just as the planet heats up faster than ever.

The Paradox in the Data

Researchers at Queen Mary University of London analyzed 809 ecological communities spanning marine, freshwater, and terrestrial ecosystems over the past century. They expected to find species turnover accelerating as warming intensified—animals and plants fleeing inhospitable conditions, new arrivals colonizing freshly suitable habitat, the whole biological deck reshuffling faster and faster.

Instead, they found the opposite. Species turnover has slowed by roughly one-third since 1975, the very year global surface temperatures kicked into a higher gear. The pattern holds across continents and ecosystem types. Coastal tide pools, mountain bird communities, freshwater lakes—all show the same counterintuitive trend.

The finding challenges a basic assumption about how ecosystems respond to climate change. We've imagined warming as an accelerant, speeding up the rate at which species compositions change. But the BioTIME database, which aggregates biodiversity surveys from the past hundred years, tells a different story. Nature's "self-repairing engine," as lead author Emmanuel Nwankwo calls it, is slowing down precisely when it should be revving up.

The Multiple Attractors Phase

Bunin's theoretical work suggested ecosystems could exist in a state he called the "Multiple Attractors phase." In this regime, internal biological interactions—competition, predation, facilitation—drive constant species turnover even when external conditions remain stable. No single species combination dominates for long. The system perpetually cycles through different configurations, like a game where no player can win permanently.

This matters because ecologists have traditionally viewed species turnover as primarily driven by external forces: climate shifts, habitat changes, human disturbance. If Bunin's theory holds, much of the compositional change we've observed historically might stem from ecosystems' intrinsic dynamics rather than environmental forcing.

The QMUL study provides the first strong empirical evidence that natural ecosystems actually operate this way. The slowdown in turnover makes sense if you accept that ecosystems need a large regional pool of species to keep the game going. When biodiversity declines at broad scales—through habitat destruction, fragmentation, or species extinctions—there are simply fewer players available to cycle in.

What's Choking the Engine

The mechanism behind the slowdown appears straightforward: environmental degradation has shrunk the regional species pools that supply colonizers to local communities. An ecosystem might lose a species through normal competitive dynamics, but if the surrounding landscape no longer harbors suitable replacements, that empty slot stays vacant. Multiply this across hundreds of species and thousands of communities, and turnover rates decline globally.

Axel Rossberg, the study's co-author, notes they were surprised by the effect's magnitude. A one-third reduction in turnover rates represents a substantial change in how ecosystems function. It's not a subtle statistical artifact buried in the noise—it's a clear signal emerging from communities worldwide.

This creates an unsettling possibility: ecosystems that appear stable might actually be sick. We tend to view compositional stability as healthy—a sign that communities are resilient, resistant to disruption. But if that stability results from depleted species pools rather than genuine equilibrium, we're mistaking stagnation for strength.

The Attribution Problem

The findings complicate how we interpret ecological change. When researchers document shifting species compositions, the default assumption has been that external drivers—particularly climate change—are responsible. This study suggests many historical changes reflected natural dynamics inherent to how ecosystems operate.

That doesn't mean climate change is irrelevant. Nwankwo emphasizes that human impacts clearly contribute to the turnover slowdown, and warming will eventually dominate as temperatures continue rising. But for now, attributing specific compositional changes to climate requires more caution than ecologists have typically exercised.

The distinction matters for conservation. If we misdiagnose natural turnover as climate-driven disruption, we might implement unnecessary interventions. Conversely, if we mistake slowed turnover for stability, we might miss warning signs of biodiversity collapse at regional scales.

When Ecosystems Stop Breathing

Think of species turnover as an ecosystem's metabolism—the rate at which it processes and renews itself. A slowing metabolism doesn't necessarily mean death, but it signals something wrong with the organism's basic functioning.

The slowdown might also explain why some ecosystems seem less responsive to conservation efforts than expected. If regional species pools are too depleted to supply colonizers, local restoration projects face an uphill battle. You can improve habitat quality, but if there are no species available to recolonize, the ecosystem remains impoverished.

This connects to a broader pattern ecologists are documenting: the homogenization of Earth's biota. As common, generalist species spread and specialists disappear, regional diversity declines even if local diversity remains stable. The QMUL study suggests this homogenization has functional consequences beyond simple species counts—it's literally slowing down ecosystem dynamics.

The Slower Catastrophe

Climate change might be unfolding differently than we imagined. Instead of rapid, visible reshuffling—species frantically relocating, ecosystems visibly transforming—we're seeing a slower, quieter degradation. The machinery keeps running, but with less vitality, like an engine gradually losing compression.

This matters because it affects how we monitor ecosystem health. If we're watching for acceleration—expecting turnover to speed up as warning signs of climate impacts—we might miss the actual signal: a dangerous deceleration indicating that ecosystems have lost the biodiversity they need to adapt.

The study doesn't offer easy solutions, but it reframes the problem. Protecting regional biodiversity becomes even more critical, not just for preserving individual species but for maintaining the ecological processes that depend on large species pools. Without that diversity, ecosystems lose their ability to self-renew, regardless of how we manage local habitats.

Nature's game of rock-paper-scissors requires enough players to keep going. We're discovering what happens when the players disappear: the game doesn't speed up or become more chaotic. It just slowly stops.