World's biodiversity drops below "safe" levels: study

Changes in land use have caused global biodiversity to fall below what was considered "safe" levels, threatening efforts toward long-term sustainable development, a new study said Thursday.

The study, published in the U.S. journal Science, analyzed 2.38 million records for more than 39,100 species at 18,600 sites to estimate how biodiversity in every square kilometer land has changed since before humans modified the habitat.

For 58.1 percent of the world's land surface, where 71.4 percent of the human population live, the level of biodiversity loss is substantial enough to question the ability of ecosystems to support human societies, it found.

The loss due to changes in land use puts levels of biodiversity beyond the recently proposed planetary boundaries, an international framework that defines a safe operating space for humanity.

"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," lead researcher Tim Newbold from the University College London said in a statement.

"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," Newbold said.

The study found that grasslands, savannas and shrublands were most affected by biodiversity loss, followed closely by many of the world's forests and woodlands.

It suggested that 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.

The researchers also 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 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," added Dr Newbold. Endit