Rapidly increasing ocean acidification is combining with rising water temperatures, hypoxic “dead zones,” and torrents of trash to threaten marine species around the globe, a new study has concluded.
Acidification levels are on the rise thanks to the burning of fossil fuels, and the worsening water quality could have ripple effects down the ocean food chain.
Since ocean acidification happens extremely fast compared to natural processes, only organisms with short generation times, such as micro-organisms, are able to keep up,” the authors of the study Exploring Ocean Change: Biological Impacts of Ocean Acidification found.
Marine life such as crustaceans and organisms that create calcified shelters for themselves in the oceans were thought to be most at risk, because acid seas would hinder them forming shells. However, the research shows that while these are in danger, perhaps surprisingly, some – such as barnacles – are often unaffected, while the damage from acidification is also felt much higher up the food chain, into big food fish species.
Atlantic cod in the Baltic and Barents seas, for example, could be one-quarter the size they are today by the end of the century, according to the scientists, who conducted the study as part of the Biological Impacts of Ocean Acidification group (known as Bioacid), a German network of researchers. The group conducted the study with the support of the German government.
The study was initiated well before governments signed a global agreement on climate change at Paris in 2015, and highlights how the Paris agreement to hold warming to no more than 2C may not be enough to prevent further acidification of the world’s seas.
President Trump decided to withdraw the U.S. from the Paris agreement in June. A meeting among the remaining governments is planned for November and the study’s authors hope ocean acidification will be among the topics discussed.
Ocean acidification is another effect of pouring carbon dioxide into the atmosphere, as the gas dissolves in seawater to produce weak carbonic acid. Since the industrial revolution, the average pH of the ocean has been found to have fallen from 8.2 to 8.1, which may seem small but corresponds to an increase in acidity of about 26%. Measures to reduce the amount of carbon dioxide reaching the atmosphere can help to slow down this process, but only measures that actively remove carbon already in the atmosphere will halt it, because of the huge stock of carbon already in the air from the burning of fossil fuels.
So-called “direct-air capture” technology to pull CO2 directly from the atmosphere is in its infancy, but recent progress has been reported. Whether it will be enough to save marine ecosystems around the globe is an open question, though.