OCEAN ACIDIFICATION: 5 things you should know

For World Water Day last week, we wanted to talk about the biggest body of water we know of, and how our increasing carbon emissions are damaging it. In other words, we’d like to explore ocean acidification.

Ocean acidification occurs when excess carbon emissions caused by human activity are absorbed by our oceans. This lowers its pH levels and makes the oceans more acidic, which has widespread impact on the delicate marine ecosystem. The acidity of the ocean has historically (pre industrial revolution) been alkaline. Since the industrial revolution the pH, or measure of alkalinity/acidity, of the oceans has dropped from 8.2 to 8.1 and is expected to reach 7.7 by 2100. The pH scale is logarithmic, so a 0.5 change in pH is significant.

Here are five things you should know about how this might affect our climate and your dinner plate:

The ocean absorbs a quarter of our emissions

Since the industrial era, the ocean has absorbed 252 billion tonnes of CO₂ from the atmosphere, about 25% of all emissions caused by human activity. This has caused a 26% rise in ocean acidity levels.

The rate of ocean acidification today is 10 times faster today than in the last 55 million years. By 2100, ocean acidity is expected to go up by 170%.

Ocean acidification may mean big changes to marine life

Rising CO₂ levels in water causes a lowering of carbonate ions – which are essential for marine species to grow their hard-exterior calcium carbonate shells. The expected rise in acidity by 2100 means crustaceans will find it increasingly difficult to build their outer shell, and even worse, the shells and corals will begin to dissolve in the more acidic ocean. A loss in a substantial part of the ocean habitat and food chain will have knock on effects for the species that rely on these organisms. The depleting coral reefs are especially concerning as they support about 25% of all marine life on the planet.

We rely on the ocean even if we’re not the ones living in it

The ocean affects our daily lives possibly more than you think. It provides us with food, medicine, jobs and transportation among many other things.

It also plays a vital role in maintaining climate zones and weather patterns. The ocean spans across approximately 71% of earth’s surface and it absorbs most of the sun’s radiation, particularly the waters near the equator. Ocean currents then act like conveyor belts, distributing warm water and precipitation from the equator to other parts of the world.

The waters around New Zealand and Australia are likely to acidify faster

The rate of CO₂ absorption isn’t uniform in all areas of the ocean. Several factors like large waves, wind and increased solubility of CO₂ in cold waters makes for higher rate of acidification of waters around New Zealand and Tasmania, compared to other parts of the world.

The New Zealand marine industry is under threat

Vulnerability of marine species to ocean acidification also includes many sources of seafood like snapper, kina, paua and oysters. The New Zealand seafood industry earns around $2 billion per year, employing over 20,000 people. Damage to the marine ecosystem and drop in production of seafood could have a severe impact on our communities and people who depend on the industry for their livelihood.

Enviro-Mark Solutions Chief Executive and marine biologist Dr Ann Smith says ocean acidification is an under-recognised impact of climate change:

“It’s important to recognise that climate change is not just about global temperature rise, but it is also significantly impacting ecosystems, our oceans and our economy.

“How can we curb the negative impacts of ocean acidification? The answer is simple – reduce your emissions and look for low carbon goods and services when you make purchasing decisions”.

Check out our recent article on specific steps on how individuals can help curb emissions.

If you’re part of a business wanting to play your part, get in touch with our experts to find out how our carboNZero and CEMARS certification programmes can give you a framework to reduce your emissions and support your organisations’ sustainability journey.