Emissions of CO2 driving rapid oceanic acidification

The world's oceans are becoming acidic at an "unprecedented rate", more rapidly than at any time in the past 300 million years. In their strongest statement yet on this issue, scientists say acidification could increase by 170% by 2100. They say that some 30% of ocean species are unlikely to survive in these conditions. The researchers conclude that human emissions of CO2 are clearly to blame. The study will be presented at global climate talks in Poland next week.

In 2012, over 500 of the world's leading experts on ocean acidification gathered in California. Led by the International Biosphere-Geosphere Programme, a review of the state of the science has now been published. This Summary for Policymakers states with "very high confidence" that increasing acidification is caused by human activities which are adding 24 million tonnes of CO2 to oceans every day.

Scientists have identified thousands of sites in the Arctic where methane that has been stored for many millennia is bubbling into the atmosphere. The methane has been trapped by ice, but is able to escape as the ice melts. Writing in the journal Nature Geoscience, the researchers say this ancient gas could have a significant impact on climate change. Methane is the second most important greenhouse gas after CO2 and levels are rising after a few years of stability. There are many sources of the gas around the world, some natural and some man-made, such as landfill waste disposal sites and farm animals. Tracking methane to these various sources is not easy. But the researchers on the new Arctic project, led by Katey Walter Anthony from the University of Alaska at Fairbanks (UAF), were able to identify long-stored gas by the ratio of different isotopes of carbon in the methane molecules. Using aerial and ground-based surveys, the team identified about 150,000 methane seeps in Alaska and Greenland in lakes along the margins of ice cover. Local sampling showed that some of these are releasing the ancient methane, perhaps from natural gas or coal deposits underneath the lakes, whereas others are emitting much younger gas, presumably formed through decay of plant material in the lakes. "We observed most of these cryosphere-cap seeps in lakes along the boundaries of permafrost thaw and in moraines and fjords of retreating glaciers," they write, emphasising the point that warming in the Arctic is releasing this long-stored carbon.