It's Coming

‘Ticking time bomb’: Ocean acidity crosses vital threshold, study finds

The deep oceans have crossed a crucial boundary that threatens their ability to provide the surface with food and oxygen, a new study finds.

Nearly two-thirds of the ocean below 200 meters, or 656 feet, as well as nearly half of that above, have breached “safe” levels of acidity, according to findings published on Monday in Global Change Biology.

The fall in ocean pH is “a ticking time bomb for marine ecosystems and coastal economies,” Steve Widdicombe, director of science at the United Kingdom’s Plymouth Marine Laboratory (PML), said in a statement.

The study was funded in part by the National Oceanographic and Atmospheric Administration (NOAA), a federal agency that has been targeted for steep cuts by the Trump White House, in large part because of its role in investigating climate change.

Some of the biggest changes in deep water are happening off the coast of western North America, home to extensive crab and salmon fisheries, the study found.

The core problem is one scientists have warned about for a long time: the continued global burning of fossil fuels, which releases carbon dioxide — an acid when dissolved in water — is making the seas and oceans more acidic.

Or, technically, it’s making them less basic, which is to say: Less hospitable to species such as corals and clams that form the foundation of the ocean’s ecosystem.

“Most ocean life doesn’t just live at the surface — the waters below are home to many more different types of plants and animals,” lead author Helen Findlay of PML. “Since these deeper waters are changing so much, the impacts of ocean acidification could be far worse than we thought.”

As of five years ago, Findlay’s study noted, the oceans may have crossed a critical threshold in which oceanic levels of calcium carbonate — the main ingredient in limestones, and also the shells of those animals — fell to more than 20 percent below pre-industrial levels.

If true, that shift would mean the Earth has passed seven out of nine of the critical “planetary boundaries” needed to maintain its ecosystem, as the Potsdam Institute for Climate Impact Research found last year.

The nine critical planetary boundaries are thresholds that scientists have identified within which humanity can safely operate to maintain a stable and healthy Earth system. These boundaries relate to different aspects of the planet's functioning, and exceeding them can lead to abrupt or irreversible environmental changes with significant consequences. 

The nine planetary boundaries are:

1. ✔︎ Climate Change: Increased greenhouse gas emissions and aerosols in the atmosphere, leading to warming and other climate impacts
2. ✔︎ Change in Biosphere Integrity: Loss of biodiversity and species extinction, impacting ecosystem services and resilience
3. ➞ Stratospheric Ozone Depletion: Thinning of the ozone layer, increasing harmful UV radiation at the Earth's surface
4. ✔︎ Ocean Acidification: Increased acidity of ocean water due to the absorption of atmospheric CO2, impacting marine life and ecosystems
5. ✔︎ Modification of Biogeochemical Flows: Altering the natural cycles of nitrogen and phosphorus, which can lead to pollution and other environmental issues
6. ✔︎ Land System Change: Deforestation, desertification, and other changes in land use that can disrupt ecosystems and the carbon cycle
7. ✔︎ Freshwater Use: Over-extraction and pollution of freshwater resources, impacting ecosystems and human populations
8. ➞ Atmospheric Aerosol Loading: Changes in the amount of airborne particles in the atmosphere, affecting climate and air quality
9. ✔︎ Novel Entities: Introduction of synthetic chemicals and other new substances into the environment, potentially causing unforeseen impacts

That shift, Widdicombe of the Marine Lab said, means “we’re witnessing the loss of critical habitats that countless marine species depend on.”

“From the coral reefs that support tourism to the shellfish industries that sustain coastal communities,” he added, “we’re gambling with both biodiversity and billions in economic value every day that action is delayed.”

The further implications are even more serious. The reasons for the ocean’s rise in acid, or fall in base, is that its waters have absorbed about one-third of all the carbon dioxide released by surface burning of coal, oil and gas.

But the more carbon dioxide it absorbs, the lower its ability to absorb more — meaning faster warming on the surface.

Making that dynamic even more dramatic, seas and oceans have also absorbed 90 percent of the global heating that the Earth’s surface would have otherwise experienced, according to NASA.

In addition to absorbing heat and carbon dioxide, the ocean also provides 50 percent of the Earth’s oxygen — which comes from the very marine ecosystems that warming and acidification are threatening.

Ecosystem loss and fossil fuel burning mean that levels of oxygen below the surface are decreasing, as, more slowly, is oxygen above the surface.