The exact causes behind the Permian-Triassic mass extinction have been much debated. Two separate pulses of CO2 into the atmosphere - a "one-two punch" - may have helped fuel the die-off, new research suggests. Changes to ocean acidity would have been one of the consequences, according to the study in Science journal. Computer models suggested that this CO2 may have been released by massive bouts of volcanism from the Siberian Traps, now represented as a large region of volcanic rock in northern Eurasia. The Permian-Triassic mass extinction, which took place 252 million years ago, wiped out more than 90% of marine species and more than two-thirds of the animals living on land. The event is thought to have played out over a 60,000-year period and acidification of the oceans lasted for about 10,000 years. The team led by Dr Matthew Clarkson from the University of Edinburgh analysed rocks unearthed in the United Arab Emirates - which were on the ocean floor at the time. The rocks preserve a detailed record of changing oceanic conditions at the time. They then developed a climate model to work out what drove the extinction. The researchers think the rapid rate of release of carbon was a crucial factor in driving the ocean acidification. The carbon was released at a similar rate to modern emissions. Dr Clarkson commented: "Scientists have long suspected that an ocean acidification event occurred during the greatest mass extinction of all time, but direct evidence has been lacking until now.

Corals are likely to suffer as a result of the changes to our oceans The health of the world’s oceans is deteriorating even faster than had previously been thought, a report says. A review from the International Programme on the State of the Ocean (IPSO), warns that the oceans are facing multiple threats. They are being heated by climate change, turned slowly less alkaline by absorbing CO2, and suffering from overfishing and pollution. The report warns that dead zones formed by fertiliser run-off are a problem. It says conditions are ripe for the sort of mass extinction event that has afflicted the oceans in the past. It says: “We have been taking the ocean for granted. It has been shielding us from the worst effects of accelerating climate change by absorbing excess CO2 from the atmosphere. “Whilst terrestrial temperature increases may be experiencing a pause, the ocean continues to warm regardless. For the most part, however, the public and policymakers are failing to recognise - or choosing to ignore - the severity of the situation.” It says the cocktail of threats facing the ocean is more powerful than the individual problems themselves. Coral reefs, for instance, are suffering from the higher temperatures and the effects of acidification whilst also being weakened by bad fishing practices, pollution, siltation and toxic algal blooms. IPSO, funded by charitable foundations, is publishing a set of five papers based on workshops in 2011 and 2012 in partnership with the International Union for Conservation of Nature (IUCN’s) World Commission on Protected Areas.

Ocean Acidification destroying Antarctic marine life

The research took place in the Southern Ocean

Marine snails in seas around Antarctica are being affected by ocean acidification, scientists have found.

An international team of researchers found that the snails' shells are being corroded. Experts says the findings are significant for predicting the future impact of ocean acidification on marine life. The results of the study are published in the journal Nature Geoscience. The marine snails, called "pteropods", are an important link in the oceanic food chain as well as a good indicator of ecosystem health.

"They are a major grazer of phytoplankton and... a key prey item of a number of higher predators - larger plankton, fish, seabirds, whales," said Dr Geraint Tarling, Head of Ocean Ecosystems at the British Antarctic Survey (BAS) and co-author of the report.