Nature's engine that counters warming, biodiversity loss may be slowing down, study suggests

New Delhi, Feb 11 (PTI) A new study has found that nature's "self-repairing engine" that counters global warming and biodiversity loss could be slowing down, contrary to the expectation that it might be speeding up.

Researchers at Queen Mary University of London said that as temperatures rise and climatic zones shift, species will face a local extinction and colonise new habitats at an ever-increasing rate, leading to a rapid reshuffling of ecological communities.

The team analysed data from 'BioTIME', an open-access global database of biodiversity surveys, spanning marine, freshwater, and terrestrial ecosystems over the last century.

The analysis compared species turnover rates -- the rate at which species replace each other -- focussed on the time period since the 1970s, a time marked by a documented acceleration in global surface temperatures and environmental shifts, the researchers said.

"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," lead author Emmanuel Nwankwo, a postdoctoral researcher, said.

Results from the analysis revealed that contrary to the expectation that external climate forces would drive a faster change, turnover over 1-5 year periods tended to become slower -- the slowdown was consistent across diverse environments such as terrestrial bird communities or the seabed.

"We were surprised how strong the effect is. Turnover rates typically declined by one third," co-author Axel Rossberg, professor in theoretical ecology, said.

"We expect either an acceleration of turnover with accelerating climate change or constant turnover if intrinsic mechanisms dominate," the authors wrote.

"Surprisingly we find instead 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," they said.

The study's results suggest that communities analysed are not merely reacting passively to external climate driver, the researchers said.

Instead, the species appear to be operating in a state known as the 'Multiple Attractors' phase predicted by theoretical physicist Guy Bunin in 2017, they said, explaining that the phase refers to 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 study now provides strong empirical evidence that this multiple attractors phase exists and actually dominates nature, the team said.

In a healthy 'multiple attractors phase' ecosystem, a large pool of potential colonisers keeps the revolving door of species turnover moving, the researchers said.

However, with human activity degrading habitats and reducing the regional pools, the number of potential colonisers drops, which slows the pace at which species replace one another, they said.

The authors suggested 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, they said. PTI KRS KRS MAH MAH