Biodiversity is below safe levels across more than half of world's land – study

Habitat destruction has reduced the variety of plants and animals to the point that ecological systems could become unable to function properly, with risks for agriculture and human health, say scientists
Adam Vaughan The Guardian 14 Jul 16;

The variety of animals and plants has fallen to dangerous levels across more than half of the world’s landmass due to humanity destroying habitats to use as farmland, scientists have estimated.

The unchecked loss of biodiversity is akin to playing ecological roulette and will set back efforts to bring people out of poverty in the long term, they warned.

Analysing 1.8m records from 39,123 sites across Earth, the international study found that a measure of the intactness of biodiversity at sites has fallen below a safety limit across 58.1% of the world’s land.

Under a proposal put forward by experts last year, a site losing more than 10% of its biodiversity is considered to have passed a precautionary threshold, beyond which the ecosystem’s ability to function could be compromised.

“It’s worrying that land use has already pushed biodiversity below the level proposed as a safe limit,” said Prof Andy Purvis, of the Natural History Museum, and one of the authors. “Until and unless we can bring biodiversity back up, we’re playing ecological roulette.”

Researchers said the study, published in the journal Science on Thursday, was the most comprehensive examination yet of biodiversity loss. The decline is not just bad news for the species but in the long term could spell problems for human health and economies.

“If ecosystem functions don’t continue, then yes it affects the ability of agriculture to sustain human populations and we simply don’t know at which point that will be reached,” said Dr Tim Newbold, lead author of the work and a research associate at University College London. “We are entering the zone of uncertainty.”

He added that while to an extent people could use technological solutions to replicate the functions of nature, such as pollinators, there were limits to how much humans could compensate for the loss of species.

“Such widespread transgression of safe limits suggests that biodiversity loss, if unchecked, will undermine efforts toward long-term sustainable development,” the paper said.

Dr Tom Oliver, who was not involved in the study, wrote in a separate commentary in Science that: “It is a tricky problem to say how much biodiversity loss is too much. However, we can be certain that inaction commits us to a future with substantial costs to human wellbeing.”

The study found that different types of habitat had lost more biodiversity where they were biomes that humans lived in, such as grasslands. Tundra and boreal forests, by contrast, were the least affected. The biggest cause of natural habitats being changed was due to agriculture, rather than urbanisation.

The study does come with some caveats. Foremost is that scientists cannot say exactly what a dangerous degree of biodiversity loss would be – it could be the 10% threshold agreed on, but the authors admit that as much as a 70% loss in variety could count as the safe limit.

The team looked at 1sq km-sized sites around the world, using the latest records that would give a geographically comprehensive picture, including species data from 2005 and human population numbers from 2000, when there were 6 billion people worldwide.

Since then, the global population has grown to 7 billion and governments have been lambasted for failing to stem biodiversity loss, suggesting the real world percentage of sites passing the safety threshold today is even higher.

Newbold said that while losses in the interim would not be uniformly true, because of conservation efforts in certain parts of the world, “on average, we would predict in intervening period, there has been further loss.”


Biodiversity plunges below 'safe' levels: study
AFP Yahoo News 15 Jul 16;

Miami (AFP) - Having a range of different plant and animal species helps guarantee the health of the Earth, but a study Thursday suggested that biodiversity may be declining beyond safe levels.

On 58 percent of the world's land surface, which is home to 71 percent of the global population, "the level of biodiversity loss is substantial enough to question the ability of ecosystems to support human societies," said the report in the US journal Science.

Researchers at University College London based their study on data from hundreds of international scientists, crunching 2.38 million records for more than 39,000 species at more than 18,000 sites in the world.

They sought to estimate how biodiversity has changed over time, particularly since humans arrived and built on land.

Areas most affected included grasslands, savannas and shrublands, followed by many of the world's forests and woodlands, said the report.

Using a reference known as the Biodiversity Intactness Index (BII), which captures changes in species abundance, researchers said a safe limit of change is generally considered about a 10 percent reduction in BII.

In other words, "species abundance within a given habitat is 90 percent of its original value in the absence of human land use," said the report.

The study showed that global biodiversity has fallen below that threshold, to 84.6 percent.

"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," said lead researcher Tim Newbold of UCL.

"In many parts of the world, we are approaching a situation where human intervention might be needed to sustain ecosystem function."

The biggest changes have been happening in the most heavily populated areas, raising concern about the potential impact on human health as well.

"It's worrying that land use has already pushed biodiversity below the level proposed as a safe limit," said co-author Andy Purvis of the Natural History Museum, London.

"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," he added.

"Until and unless we can bring biodiversity back up, we're playing ecological roulette."


Why You Should Fear an “Ecological Recession”
Justin WorlandTime 15 Jul 16;

More than half of the world may be experiencing a dangerous loss in biodiversity

Human efforts to slow biodiversity loss are falling short across the globe, which could in turn harm future human development and wellbeing, according to new research.

Researchers behind study, published in the journal Science, found that human-caused pressures like land use change—the destruction of natural habitats often for timber, agriculture or residential developments—have cause biodiversity to fall to unsustainable levels more than half of the world’s surface. On average, human activity has driven away 15% of species that would have been present otherwise in locations across the globe, according to the study.

“Decision-makers worry a lot about economic recessions,” said author Andy Purvis, a professor at the Natural History Museum in London in a press release. “But an ecological recession could have even worse consequences—and the biodiversity damage we’ve had means we’re at risk of that happening.”

Determining exactly what level of biodiversity loss can be sustained without damaging human wellbeing is a difficult challenge. Previous research has suggested that a decline of more than 10% in the number of species in a certain area could be a dangerous threshold, but even that study notes that the figure is far from certain.

Healthy biodiversity plays a crucial role in a number of functions that support human life, including pollination and pest control, both of which support agriculture. Other vulnerable species—like some types of trees and plants—suck up carbon dioxide that would otherwise contribute to climate change.

“It is a tricky problem to say how much biodiversity loss is too much,” says Tom Oliver, an associate professor in landscape ecology, in an opinion piece accompanying the study. “However, we can be certain that inaction commits us to a future with substantial costs to human well-being.”

Researchers looked at nearly 2.2 million records on 39,000 species around the globe, making the study the most detailed work evaluating how land change affects biodiversity. Locations inhabited by humans tend to be the most vulnerable to declines in biodiversity, according to the study.

A number of initiatives are underway to address biodiversity loss, including the 1993 Convention on Biological Diversity, an international treaty that establishes a framework for dealing with the issue. But, with biodiversity showing no signs of slowing—and other phenomena like climate change worsening the problem—change may not come soon enough.