Biodiversity falls below 'safe levels' globally

Levels of global biodiversity loss are found to be high enough that they could affect ecosystems' ability to support human societies.

An international team of researchers has concluded that biodiversity loss is beyond the safe limit in most of the world, after investigating the effect of global habitat loss.

Ecosystems support human societies by providing us with resources like food, fuel and fibres, and also perform vital roles such as pollinating crops and cycling nutrients. Crossing the safe limit boundary means many ecosystems can no longer perform all their normal functions.

A team of scientists including researchers from UCL, the Natural History Museum, UNEP-WCMC, Imperial College London and CSIRO, found that grasslands, savannas and shrublands were most affected by biodiversity loss on average, followed closely by many of the world’s forests and woodlands.

The study, published today in Science, reports that levels of biodiversity loss are so high that, if left unchecked, they could undermine efforts towards long-term sustainable development – economic development without the loss of natural resources.

According to the authors, for 58 per cent of the world’s land surface – an area that is home to 71 per cent of the global population – the level of biodiversity loss is substantial enough to question the ability of ecosystems to support human societies.

The loss is due to changes in land use and puts levels of biodiversity beyond the ‘safe limit’ recently proposed by the planetary boundaries – an international framework that defines a safe operating space for humanity.

Below safe limits

“It’s worrying that land use has already pushed biodiversity below the level proposed as a safe limit,” said study co-author Professor Andy Purvis from the Department of Life Sciences at Imperial and the Natural History Museum. Several students from the two institutions’ joint Masters programmes also played key roles in collating the data.

Professor Purvis added: “Decision-makers worry a lot about economic recessions, but an ecological recession could have even worse consequences – and the biodiversity damage we’ve had means we’re at risk of that happening. Until and unless we can bring biodiversity back up, we’re playing ecological roulette.”

The team used data contributed by hundreds of scientists across the globe to analyse 2.38 million records for 39,123 species at 18,659 sites captured in the database of the PREDICTS project. The analyses were then applied to estimate how biodiversity in every square kilometre of land has changed since before humans modified the habitat.

They found that areas with traditionally high biodiversity that have suffered habitat loss in the past show high biodiversity decline. Other high biodiversity areas, such as Amazonia, which have seen less land use change retain higher levels of biodiversity, raising the possibility that proactive conservation could prevent future losses.

physical and psychological wellbeing

Lead researcher, Dr Tim Newbold from UCL said: “The greatest changes have happened in those places where most people live, which might affect physical and psychological wellbeing. To address this, we would have to preserve the remaining areas of natural vegetation and restore human-used lands.”

The team hope the results will be used to inform conservation policy, nationally and internationally. To facilitate this, they have made the maps from this paper and all of the underlying data publicly available.

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'Has land use pushed terrestrial biodiversity beyond the planetary boundary? A global assessment’ by T Newbold et al is published in Science.