2023 GIEC synthèse

Mass extinctions during the past 500 million y rapidly removed branches from the phylogenetic tree of life and required millions of years for evolution to generate functional replacements for the extinct (EX) organisms. Here we show, by examining 5,400 vertebrate genera (excluding fishes) comprising 34,600 species, that 73 genera became EX since 1500 AD. Beyond any doubt, the human-driven sixth mass extinction is more severe than previously assessed and is rapidly accelerating. The current generic extinction rates are 35 times higher than expected background rates prevailing in the last million years under the absence of human impacts. The genera lost in the last five centuries would have taken some 18,000 y to vanish in the absence of human beings. Current generic extinction rates will likely greatly accelerate in the next few decades due to drivers accompanying the growth and consumption of the human enterprise such as habitat destruction, illegal trade, and climate disruption. If all now-endangered genera

In a speech about climate change from April 4th of this year, UN General Secretary António Guterres lambasted “the empty pledges that put us on track to an unlivable world” and warned that “we are on a fast track to climate disaster” (1). Although stark, Guterres’ statements were not novel. Guterres has made similar remarks on previous occasions, as have other public figures, including Sir David Attenborough, who warned in 2018 that inaction on climate change could lead to “the collapse of our civilizations” (2). In their article, “World Scientists’ Warning of a Climate Emergency 2021”—which now has more than 14,700 signatories from 158 countries—William J. Ripple and colleagues state that climate change could “cause significant disruptions to ecosystems, society, and economies, potentially making large areas of Earth uninhabitable”