Climate change and high rates of extinctions of animals and plants are pushing the Earth into a danger zone for humanity, according an international team of 18 experts, who expanded on a 2009 report about “planetary boundaries” for safe human use.
Of a total of nine boundaries assessed, freshwater use, ocean acidification and ozone depletion were judged to be within safe limits. Others, including levels of airborne pollution, were yet to be properly assessed. The report defined climate change and loss of species as two core areas of concern. Each “has the potential on its own to drive the Earth System into a new state should they be substantially and persistently transgressed,” the authors wrote.
Rising concentrations of carbon dioxide, the main greenhouse gas, are about 397 parts per million in the atmosphere, above 350 ppm that the study set as the boundary for safe use. The study said that rates of extinctions of animals and plants, caused by factors ranging from pollution to deforestation, were 10 to 100 times higher than safe levels.