Oceans dangerously acidic from carbon emissions, report warns
Greenhouse gas emissions from the burning of fossil fuels have pushed the acidity of the world's oceans past a safe threshold, scientists warn, threatening their ability to sustain shellfish and corals and help us in the fight against climate change.
A new report says that ocean acidification is the latest "planetary boundary" to be crossed, a reference to a set of warning signs related to key planetary systems that keep the Earth safe for human civilization.
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Other planetary boundaries that have already been crossed — including dangerous levels of chemical pollution, the warming atmosphere and changes to the nutrient cycle — have already signalled threats to people.
"Go outside of these boundaries and you first enter a danger zone, with higher risk of causing changes that would undermine that ability to support human life and human development," said Johan Rockström, director of the Potsdam Institute for Climate Impact Research, which is behind the Planetary Health Check report released on Wednesday.
(Максим Шмаков/ iStock/ Getty Images Plus)
"And once you are at the upper end of the uncertainty range ... you enter the red zone, the high-risk zone where most science agrees that we are very likely to depress buttons that will cause irreversible changes, basically committing ourselves to drifting away from livable conditions on Earth."
Adding the oceans to the planetary boundaries list is a major concern because of the billions of people who depend on them. Continuing ocean acidification could not only destroy fisheries that people rely on for food but reduce the ability of the ocean to absorb carbon dioxide and moderate global warming.
Material costs going up
As humans burn fossil fuels and pump carbon dioxide into the atmosphere, it's estimated that the ocean is absorbing more than a quarter of that CO2.
"Just like when we add carbon dioxide to Coke or soda, that makes the soft drink more acidic," said Christopher Harley, a professor who studies climate change and the ocean at the University of British Columbia.
Dead coral. (Getty Images/Placebo365/1172693906-170667a)
But when CO2 is absorbed, the chemical process effectively lowers the availability of a mineral that certain marine life — from shellfish to coral — need to develop their bodies.
"It makes it harder to build shells — and you need to add shell if you want to grow bigger," Harley explained, comparing it to the construction of a house.
"All of a sudden, the building materials become more costly. You're either going to build smaller homes or not as many."
Food for our food
The specific "building material" that the planetary boundary report measures is aragonite — a form of calcium carbonate.
The report says the aragonite saturation in the ocean is getting lower, past a safe point. Experts have seen the negative effects — from stunted larval development to weaker shells — in a range of species, including plankton, mussels, crabs and oysters.
"If you're an oyster grower, you care about that, because you want your oysters to grow quickly to market size," Harley told CBC News from Vancouver.
A Dungeness crab sits in a tank in this undated photo. The two spikes near its eyes are antenulae, which are used to smell. That ability is affected by ocean acidification. (Andrea Durant )
Cosima Porteus, assistant professor at the University of Toronto Scarborough, studied ocean acidification's impact on Dungeness crabs, a species estimated to be worth more than $250 million in exports for British Columbia.
"Crabs, in particular, have very poor vision, so they rely on other senses such as [smell] for their day-to-day lives," Porteus said. The research found that at high levels of acidification, Dungeness crabs have a reduced ability to find food, which could affect future growth.
"We potentially could see smaller animals, they probably would have less energy to put towards reproduction, so they could produce fewer eggs and offspring," Porteus told CBC News from Toronto.
Canadian waters affected
Experts point out that there is regional variability in how intensely the ocean is acidifying, and Canadian waters — at a higher latitude — are at greater risk.
"The global ocean is not changing equally or at an even rate," said Matt Miller, a researcher at the University of Victoria's School of Earth and Ocean sciences. "The polar regions, the Arctic, for instance, are experiencing the most drastic changes."
Iria Gimenez, research scientist at the Hakai Institute in B.C., says colder water absorbs more carbon dioxide and melting glaciers contribute to this problem, putting us at a "higher baseline."
Iria Gimenez, research scientist at the Hakai Institute, works out of the Marna Lab at Quadra Island in British Columbia. The lab studies ocean acidification's impact on shellfish and other creatures. (Grant Callegari/Hakai Institute)
"I think ocean acidification has been maybe perceived a little like this slow burn, that it doesn't have the immediate impacts of something as intense and extreme as, like, the heat dome in 2021 had for marine nearshore ecosystems," she said.
Gimenez conducts research off the coast of Quadra Island, at the northern end of B.C.'s Georgia Strait, which allows her to see up close how ocean acidification has impacted local species.
"If you're talking to the shelfish industry and communities that are very intimately connected to mussels and oysters … they will be able to tell you that they're worried" because they are seeing those species under stress, she said.
Global problem
All experts CBC News spoke to agree that these varying local effects are still part of a global problem.
"Ultimately, the main solution to this problem is a dramatic reduction in carbon dioxide emissions to the atmosphere," Gimenez said.
As the ocean absorbs carbon — and 90 per cent of the excess heat generated by the greenhouse gas effect — its ability to keep absorbing carbon will be affected, putting a massive bulwark against climate change at risk.
Underwater coral showing signs of bleaching. (Getty Images/Plaxebo365/1183278473-170667a)
"Imagine if that extra 30 per cent of CO2 … was still in the atmosphere. And imagine if all that heat was still in the atmosphere. Our lives on land would be so much worse right now," said Miller.
He points out the oceans have seen acidification before — such as 65 million years ago, when volcanic activity spewed carbon dioxide into the atmosphere.
"But even then, the rate of change was about 10 times slower than what we're seeing today.… Whether or not these animals can adapt at this quicker pace — we're not sure about."
WATCH: Heat stress leads to 'widespread' coral bleaching in Great Barrier Reef
Thumbnail courtesy of CANVA.
The story was originally written by Anand Ram, Inayat Singh and published for CBC News.
