When a meteorite hit Earth, the pH of the oceans dropped by 0.25 units, causing mass extinctions of marine life. Photo: © Andreas Wolochow / Shutterstock.com

Ocean acidification can cause the mass extinction

Carbon emissions make seas more acidic and wiped out 75 per cent of marine species around 66 million years ago, reports a new study according to the Guardian. A key impact of today’s climate crisis is that seas are again getting more acidic, as they absorb carbon emissions from the burning of coal, oil and gas. Scientists said the latest research is a warning that humanity is risking potential “ecological collapse” in the oceans, which produce half the oxygen we breathe. The researchers analysed small seashells in sediment laid down shortly after a giant meteorite hit the Earth, wiping out the dinosaurs and three-quarters of marine species. Chemical analysis of the shells showed a sharp drop in the pH of the ocean after the meteorite struck. The researchers found that the pH dropped by 0.25 pH units in the 100–1,000 years after the strike. It is possible that there was an even bigger drop in pH in the decade or two after the strike and the scientists are examining other sediments in even finer detail. The researchers said: “If 0.25 was enough to precipitate a mass extinction, we should be worried.” Researchers estimate that the pH of the ocean will drop by 0.4 pH units by the end of this century if carbon emissions are not stopped, or by 0.15 units if global temperature rise is limited to 2 °C.

Source: The Guardian 21 October 2019 https://www.theguardian.com/environment/2019/oct/21/ocean-acidification-...



In this issue