Oceans absorb up to 3 billion metric tons of carbon dioxide from the atmosphere every year, but given the rapid rise in global emissions, they cannot absorb it quickly enough. This is a problem because when carbon dioxide meets seawater, it produces a chemical reaction that causes the water’s pH levels to fall and its acidity to rise.
This process depletes the ocean of carbonate — an important building block for sea life including calcifying plankton and algae, shellfish, sea urchins and corals. Now, due to the rapid increase in global carbon emissions, our oceans are acidifying 100 times faster than at any other period over the past 55 million years.
If projected forecasts come to pass, our oceans’ surface waters could become 150 times more acidic than pre-industrialized levels. This would spell the end for numerous marine organisms, ecosystems and the livelihoods of the 3 billion people who depend on a thriving ocean.
It is the commercial staple of coastal communities, providing livelihoods for fishers and fish sellers, as well as sight-seeing boats and scuba diving opportunities that draw tourisms from all over the world. Indeed, a thriving ocean is essential to the lives of millions.
And yet, so little was said of ocean acidification in the negotiation rooms of COP27. Only just this year were the words "water" mentioned in the final declaration text from the climate convention, and while a National Ocean Acidification Plan was promised by the U.S., it will not be finalized until COP28 and may take years to implement.
Not addressing ocean acidification head-on at the UN climate conference in Sharm El-Sheikh was a missed opportunity for reducing emissions. The ocean is a natural carbon sink and the healthier it is, the more it can perform its role as a regulator of climate. Between 1992 and 2018, the world’s oceans absorbed 67 billion metric tons of CO2, almost double the total CO2 emissions from fossil fuels and industrial processes in 2020. Putting ocean health at the center of the climate agenda is therefore essential if we want to make progress on tackling the climate crisis.
Although their place on the global agenda was initially unclear, oceans fared better at COP15 — the United Nations’ Convention on Biological Diversity (CBD). This summit provided an opportunity for global leaders to give ocean acidification and other marine issues the attention they have long been due.
After many, many hours of negotiations, Target 8 in the agreed declaration specifically calls on countries to minimize the impacts of ocean acidification on biodiversity and to increase resilience through mitigation, adaptation and disaster risk reduction actions. Long-overlooked, Target 8’s adoption into the COP15 agreement shows world leaders are united in their recognition of ocean acidification as an important global issue that demands attention.
Ocean acidity decimated oyster aquaculture across the U.S. Pacific Northwest between 2005 and 2012, affecting 3,000 jobs and $110 million in revenue.
Leadership from the Global North, such as the U.S.-led pledge to conserve, protect or restore at least 30 percent of the global ocean by 2030, is especially welcome when much of the Global South’s coastal economies are made vulnerable. Nigeria is sub-Saharan Africa’s top producer of fishing and farmed fish, producing up to to 1 million metric tons of fish a year and engaging 10 million of the population in the industry. If rising acidity leads to aquaculture failure, communities and local economies here will be left critically exposed.
Even so, northern economies are not immune. In Back to Blue's recent data visualization, we highlighted the fact that ocean acidity decimated oyster aquaculture across the U.S. Pacific Northwest between 2005 and 2012, affecting 3,000 jobs and $110 million in revenue. Since then, collaboration between farmers, government and business to restore the waters has brought the industry back — but it is in no way saved yet.
We are running out of time to avoid the worst impacts of ocean acidification and we need the global community to come together. Researchers from Sweden’s Stockholm Resilience Centre created the Planetary Boundaries Framework, which designates ocean acidification as one of nine planetary tipping points — a limit that, if transgressed, could threaten civilization and life as we know it. But we can turn back the tide on ocean acidification if we act now.
The best way to avoid the most severe impacts is to rapidly and dramatically reduce carbon emissions. In tandem with this, there are mitigation schemes and solutions that can be adopted quickly and scaled regionally and globally.
Nature-based solutions, such as blue carbon habitats or coastal ecosystems, extract and store carbon, thereby reducing the amount of carbon the oceans absorb and its resulting acidity. Additionally, seagrass and mangroves in coastal wetlands also draw carbon from the atmosphere before it reaches the water, sequestering it in their roots, branches and surrounding sediment.
Similarly, marine-protected areas (MPAs) set aside by governments for long-term conservation can be redesigned to mitigate and/or adapt to the effects of ocean warming and acidification. The U.K., among other countries, is inserting climate smart decision-making into its MPA planning.
We need to tackle this crisis from all angles — through research, conservation, innovative technology, collaborative partnerships and funding. Agreement on Target 8 is a welcome milestone, but if we are to avoid the worst impacts of ocean acidification, it is time to turn this agreement into action. Equally importantly preparations already underway for COP28 of climate convention to pick this topic and give to it its due prominence.