Biodiversity levels fall below global ‘safe limit'

The spider monkey, an endangered species of Ecuador

Levels of global biodiversity loss could negatively impact on ecosystem function and the sustainability of human societies, according to new research.

The study, published today in the highly respected journal ‘Science’, has been carried out by researchers from the University of Sussex, University College London, the Natural History Museum and UNEP-WCMC. It shows that levels of biodiversity loss are now so high that if left unchecked, they could undermine efforts towards long-term sustainable development.

For 58.1% of the world’s land surface, which is home to 71.4% 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.

The team found that grasslands, savannas and shrublands were most affected by biodiversity loss, followed closely by many of the world’s forests and woodlands. They say the ability of biodiversity in these areas to support key ecosystem functions such as growth of living organisms and nutrient cycling has become increasingly uncertain.

Dr Jörn Scharlemann, from the University of Sussex, who worked on the study said: “Worryingly our study shows that biodiversity levels have now fallen below the environmental safe limits within which it’s deemed we humans can safely live.

“Use and exploitation of the world’s land by humans has come at a huge cost to the biodiversity of our planet – and it is vital governments across the world recognise this and take action now.

“Preserving the world’s remaining areas of natural vegetation and restoring human-used lands to natural vegetation would likely be extremely beneficial for biodiversity, the earth’s ecosystems, and in the long term human wellbeing.”

Lead author Dr Tim Newbold from UCL and previously at UNEP-WCMC, said: “This is the first time we’ve quantified the effect of habitat loss on biodiversity globally in such detail and we’ve found that across most of the world biodiversity loss is no longer within the safe limit suggested by ecologists.

“We know biodiversity loss affects ecosystem function but how it does this is not entirely clear. What we do know is that in many parts of the world, we are approaching a situation where human intervention might be needed to sustain ecosystem function.”

Professor Andy Purvis of the Natural History Museum, said: “It’s worrying that land use has already pushed biodiversity below the level proposed as a safe limit.

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

They found that biodiversity hotspots – those that have seen habitat loss in the past but have a lot of species only found in that area – are threatened, showing high levels of biodiversity decline. Other high biodiversity areas, such as Amazonia, which have seen no land use change have higher levels of biodiversity and more scope for proactive conservation.

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

By: Lynsey Ford
Last updated: Thursday, 28 July 2016