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Biodiversity has fallen below the 'safe threshold' in more than half of the planet

Biodiversity has fallen below the 'safe threshold' in more than half of the planet

By SINC

The Earth is becoming saturated due to the pressure exerted on it by human beings, and this will have consequences for social and economic development. In 2009, a group of scientists led by the Swedish Johan Rockström, director of the Stockholm Resilience Center, established nine planetary boundaries, an international framework that defines a safe operating space for humanity.

Climate change, loss of biodiversity, excess nitrogen and phosphorus in production, stratospheric ozone depletion, ocean acidification, global freshwater consumption, change in land use (agriculture), Air pollution and chemistry are the nine areas that if exceeded will change the environment in an abrupt and irreversible way.

An international group of scientists, led by University College London in the United Kingdom, has quantified in detail for the first time the effect of the global loss of biodiversity and reveals that pressures related to land use have greatly reduced it. According to the Biotic Integrity Index (IIB), the safe limit of biodiversity loss is 10%, that is to say that in that case 90% of the abundance of species would remain intact.

However, "the loss of biodiversity corresponds to an average of 15.4%, measured from the IIB," Tim Newbold, lead author and researcher at University College London, tells Sinc. Biodiversity would therefore be 84 , 6%, that is to say below 90%, although some researchers point out that a reduction up to 70% can be considered safe.

The work indicates that even if the appearance of new species in a certain region is taken into account, the IIB continues to be below the advisable threshold, at 88% of its value prior to the human factor.

THE BIODIVERSITY OF THE GRASSLANDS IS THE MOST AFFECTED

The study, published in Science, estimates that in 58.1% of the world's land surface - which is home to 71.4% of the world's population - local biodiversity has fallen below these planetary limits proposed by Rockström. According to scientists, the integrity of biodiversity is in decline even in the wildest areas, where many species inhabit and are considered biodiversity hotspots.

“We have come to realize that in practically the whole world the loss of biodiversity is no longer within the safe limit suggested by ecologists,” explains Tim Newbold. According to the research, nine of the 14 terrestrial biomes have exceeded the recommended safe limit for biodiversity, but this number drops to seven out of 14 if the appearance of new species is included in the assessment.

Grasslands, savannas and scrublands are the areas most affected by biodiversity loss, closely followed by many forests. “The most affected are the grasslands in temperate zones, because this is where most of the agriculture takes place. However, many tropical areas have also reached these limits due to the increasing agriculture that takes place in these areas ”, emphasizes Sinc Newbold. The Amazon, which has not experienced changes in land use, has higher levels of biodiversity.

ECOSYSTEMS LOSE THEIR FUNCTION

The work also shows that levels of global biodiversity loss could negatively affect ecosystem function and the sustainability of human societies.

“There is evidence that the loss of biodiversity can reduce ecological functions such as agricultural production, growth of living organisms, nutrient cycling and pollination. Furthermore, the loss of biodiversity makes the functions of the ecosystem under environmental changes such as climate change less likely ”, warns the scientist.

Until now, scientists were not entirely clear about how the loss of biodiversity affected ecosystem function. "What we do know is that in many parts of the world, we are approaching a situation in which human intervention may be needed to maintain this function," emphasizes the researcher.

The scientists used data from hundreds of studies and analyzed the abundance of animals, plants and fungi in 2.38 million records on 39,123 species in 18,659 locations, from natural habitats, agricultural and urban areas. The analyzes of the PREDICTS project made it possible to verify in each square kilometer of land how the habitat has changed.

The team stresses that if biodiversity loss is not controlled, efforts towards long-term sustainable development will be undermined. “Politicians are very concerned about the economic recession but the ecological one could have even worse consequences. Until we recover biodiversity, we are playing ecological roulette ”, says Andy Purvis of the Natural History Museum in London, and co-author of the study.

Newbold proposes to return to the safe limits by restoring some areas of the natural habitat and preserving the remaining areas. "We will have to restore the lands used by humans," he concludes.

Scientific American


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