Land use and related pressures have pushed biodiversity loss beyond safe levels in most of the world, threatening key ecosystem functions and long-term sustainable development, an international team of researchers has found. According to a comprehensive study published in the journal Science on July 15, habitat destruction has reduced the variety of plants and animals to the point that ecological systems are at risk of collapsing. Analysing over 2 million records for nearly 40,000 terrestrial species at 18,659 sites, the team modeled how biodiversity in every square kilometre of land has changed due to human activities. They found that for 58.1% of the world’s land surface, where 71.4% of the global population live, the level of biodiversity loss has fallen below levels that define 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,” explained lead researcher, Dr Tim Newbold from University College London. A site losing more than 10% of its biodiversity is considered to have passed beyond the ‘safe limits’ recently defined by the planetary boundaries framework. Grasslands, savannas and shrublands were most affected by biodiversity loss, followed by many of the world’s forests and woodlands. The team says 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 authors warn that levels of biodiversity loss are so high that efforts towards long-term sustainable development could be seriously undermined if the transgression of this planetary boundary is left unchecked. “It’s worrying that land use has already pushed biodiversity below the level proposed as a safe limit,” said Professor Andy Purvis of the Natural History Museum, London, who is one of the authors. “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,” he added. (ab)