CO2 Levels Approaching 'Mass Extinction' Threshold, Study Warns

Concentrations of CO2 in Earth's atmosphere could reach levels associated with 19 "mass extinctions" that have occurred in the last 534 million years within a human lifetime, warns a new study. By 2100, atmospheric CO2 levels could rise to 800 parts per million by volume (ppmv), close to the average CO2 concentrations associated with significant crashes in marine biodiversity. The study highlights that current CO2 levels are already causing losses in biodiversity, primarily through ocean acidification, which reduces the availability of calcium carbonate ions needed for organisms to build their skeletons and shells. Scientists warn that if emissions from burning fossil fuels and land conversion for agriculture are not curbed, the consequences could be severe for global biodiversity.