Ocean acidification has been in the news this week after Germany’s highly respected Potsdam Institute for Climate Impact Research released a report identifying it as close to reaching a tipping point for Earth’s sustainability.
What is Ocean Acidification?
Ocean acidification is the trend of decreasing pH in Earth's oceans, making them more acidic. It’s primarily driven by carbon dioxide (CO₂) emissions into the atmosphere. Oceans absorb around 30% of atmospheric CO₂, and when it dissolves in seawater, it reacts to form carbonic acid. This acid interacts with carbonates that marine organisms like coral, krill, prawns, and shellfish need carbonate to form their calcium carbonate (CaCO₃) shells and skeletons. With less carbonate available, these organisms face serious threats to their survival. Plankton are also affected directly and indirectly. Species like krill and plankton are also at the bottom of the food chain. This means their decline directly threatens entire ocean ecosystems and industries like fisheries.
Why is it Happening?
Ocean acidification is primarily caused by relentless burning of fossil fuels. Every time we drive a petrol or diesel vehicle, burn coal for electricity, or extract natural gas, we contribute more CO₂ to the atmosphere. Agriculture, deforestation, and industrial processes like cement production also contribute significantly.
While some of this CO₂ is absorbed by forests and other natural carbon sinks, the oceans act as one of the largest reservoirs, absorbing around 20 to 30 billion tonnes each year. The more CO₂ we emit, the more the oceans absorb, leading to faster acidification.
The rate of ocean acidification is accelerating. In the last 200 years, ocean's have seen a 30% increase in acidity. And ocean acidification is now progressing at a rate ten times faster than it ever has in the past 300 million years. If this continues, scientists estimate that marine ecosystem as we know them will soon be unrecognisable. Coral reefs, which protect coastlines and provide essential habitats for a quarter of all marine species, will become functionally extinct. Fisheries will collapse putting the food and economic security at risk for over three billion people who rely globally on them for their food and livelihood. This will have major flow-on effects as these people seek to find other food source. In Australia, at a commercial level alone, $3 billion in fisheries industry activities is at risk. This includes over $1.6 billion in export income and thousands of jobs.
What Can Be Done?
It’s simple. Ocean acidification can only be mitigated by reducing CO₂ emissions. We need urgent and large-scale action to stop burning fossil fuels from governments and corporations. And without letting them off the hook in the meantime, every individual action that each of us makes to reduce carbon pollution can also contribute.
1. Decarbonise energy: Switching to renewable energy sources, such as wind and solar will drastically cut CO₂ emissions.
2. Restore marine ecosystems: Efforts to restore kelp forests and seagrass meadows, which absorb carbon, could help buffer localised acidification and protect marine biodiversity. But they’re not a panacea. Stopping fossil fuel emissions at their source is the most important.
3. Sustainable fisheries management: Developing aquaculture practices that reduce reliance on species vulnerable to acidification can help safeguard food security.
4. Raise Awareness: talking about and sharing information on ocean acidification can increase pressure on governments and industries to adopt climate-friendly policies.
Time is Running Out
The oceans are an essential part of life on Earth and food and livelihoods for humanity. They regulate our climate and sustain biodiversity that we rely on. We also have the oceans to thank for absorbing most of the CO₂ we’ve released into the atmosphere so far. But the oceans can only take so much. They’re close to reaching a irreversible tipping point.
While ocean acidification is an alarming consequence of CO₂ emissions, it’s not too late. Urgently transitioning away from fossil fuels and protecting and restoring marine ecosystems, can slow acidification and help preserve the oceans for future generations.
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