Ocean acidification: a [pH]ishy dilemma

A few years ago, I experienced the same predicament as any other kid in my 8th grade science class: What on Earth should I choose as the topic of my science fair project? While researching ideas for an experiment, I came across an interesting one. Its ingredients? Sea shells, vinegar, water, and salt. You can probably guess what it entailed…putting the seashells into DIY sea water, then adding vinegar to see what would happen (spoiler: the seashells dissolve).

While I doubt anyone’s dumping vinegar into the sea, we’re certainly doing something similar – on a MUCH larger scale. Yep, this week’s article will be discussing ocean acidification.

What’s With All The Buzz Around pH?

Just to make sure we’re on the same page, ocean acidification is when the pH of ocean water decreases (a lower pH means something becomes more acidic). Before the Industrial Revolution, the pH of ocean water averaged out at 8.2. Now, it’s 8.1 [1]. This 0.1 difference certainly doesn’t seem significant, but pH is measured on a logarithmic scale (powers of 10). Meaning? Meaning… the ocean is 25% more acidic than it used to be!

What’s Causing The pH Change?

Carbon dioxide is certainly necessary for life on Earth (ahem, photosynthesis), but as the saying goes: Everything in moderation. As you likely know, the Industrial Revolution of the 18th and 19th centuries drastically increased our world’s CO2 emissions because the Revolution brought with it a huge swarm of fossil fuel-using factories. Carbon dioxide gas is a significant component of the huge pollution clouds that these factories belch out. The ocean absorbs this CO2, and a considerable amount of it, too: about ⅓ of the CO2 in Earth’s atmosphere [1].

CO2 gas then readily dissolves into ocean water to form a mixture of carbonic acid (H2CO3), hydrogen ions (H+), bicarbonate (HCO3–), and carbonate ions (CO32–) [2]. These accumulating hydrogen ions are the direct culprits that lower our oceans’ pH levels.

So, an increase in atmospheric CO2 levels causes the pH of seawater to decrease. But what are some common culprits of increased CO2 emissions in the first place? Here are a couple:

  • Fossil fuels: Human use of fossil fuels is responsible for the majority of CO2 emissions by FAR, at around 76-87% of total CO2 emissions annually [3]. We’re incredibly reliant on burning fossil fuels for energy – it’s used for transportation, electricity, heating, industry… the list goes on.
  • Deforestation: Deforestation, the mass cutting down of forests, accounts for another 9-11% of CO2 emissions [3]. With less trees absorbing CO2, more CO2 will be left in the atmosphere, contributing to a slew of problems along with ocean acidification (such as sea level rise and climate change).

What Are The Environmental Effects Of Ocean Acidification?

The list goes on and on, but here are some highlights:

  • Loss of Biodiversity: A LOT of marine organisms rely on carbonate as building material for their shells – crabs, mussels, clams, anything you can think of that has a shell. However, carbonate reacts with CO2 in the ocean to form bicarbonate, and this reaction leaves less carbonate to be available for shell-making. Without sufficient carbonate, these shell-terless animals will not be able to build strong shells or skeletons, decreasing their chances of survival.
  • Fisheries – Local economies that depend on shellfish are greatly affected by shellfish populations’ lowered survival rates. In Alaska, fisheries supply 100,000 jobs and account for “60% of U.S. commercial fish catch” [5]. It is evident that ocean acidification has ramifications that extend past the well-being of marine ecosystems; it directly impacts the livelihoods of people too.
  • Bleaching of Coral Reefs: You’ve probably heard of this one before, but it’s still a pressing problem. Coral reef bleaching is actually caused by an increase in ocean temperatures, but ocean acidification exacerbates the problem. Coral reefs have more difficulty “bouncing back” to health in acidic conditions because these biodiverse ecosystems also use carbonate to build themselves.
  • Food Chain Havoc – When you decrease (or eliminate) a species’ population in the food chain, a niche (role) in the ecosystem is unfulfilled. This affects almost all other organisms in the ecosystem even if they will not be directly affected by ocean acidification itself. For instance, the rapid decline of coral reefs has led to the endangerment of other species reliant on coral, such as butterflyfish [4], which then leads to the decline of other species that depend on such fish.
  • Tourism – A loss in coral reefs eliminates an important source of tourism income in coastal communities. Furthermore, “nuisance species” such as jellyfish are attracted to water with higher CO2 levels, causing popular beach areas to be cluttered with jellyfish that normally wouldn’t be there [6].

What Can I Do To Help?

  • Growing sea plants: Perhaps not the most feasible solution for the everyday person, but it is a promising initiative. In the Indo-Pacific, cultivating seagrass meadows has the potential to increase pH by 0.38 (meaning the water becomes LESS acidic!) [7]. The pH isn’t the only thing to increase; coral growth is projected to increase by 18% [7].
  • Decreasing fossil fuel use: You don’t need to have a Tesla. Even just walking helps significantly: “walking a mile and a half would release 75% less greenhouse gases than we would produce from driving the same distance” [8].
  • Supporting organizations: There are plenty of organizations that are dedicated to protecting marine ecosystems. Ocean Conservancy, NOAA’s Ocean Acidification Program, International Alliance to Combat Ocean Acidification, Earth Policy Institute (EPI)…there are plenty to look into.

There are so many more ways to prevent ocean acidification from worsening, but these are just some of the actions you can take. :) It’s important to not underestimate the importance of the ocean in our everyday lives AND the value of knowing what’s happening to it. Once again, thanks so much for caring about the Earth and stopping by our website!

Note: Bracketed numbers next to certain texts (e.g. [1], [2], etc.) indicate that the aforementioned information in the article is derived from the corresponding source in the References below.


[1] Understanding the Science of Ocean and Coastal Acidification. EPA: United States Environmental Protection Agency. (2019, August 23). https://www.epa.gov/ocean-acidification/understanding-science-ocean-and-coastal-acidification.

[2] When carbonate formation loses equilibrium ” World Ocean Review. World Ocean Review. https://worldoceanreview.com/en/wor-1/ocean


[3] Top 10 sources of CO2. Heat Power. (2019, April 2). https://heatpower.com/the-power-of-heat/the-case-against-co2/top-10-


[4] ScienceDaily. (2018, April 5). Coral bleaching threatens the diversity of reef fish. ScienceDaily. https://www.sciencedaily.com/releases/2018/04/180405150053.htm.

[5] Fisheries, N.O.A.A. Understanding Ocean Acidification. NOAA. https://www.fisheries.noaa.gov/insight/understanding-ocean-acidification.

[6] Montgomery, M. (2014, December 17). What You Need to Know About Ocean Acidification and How it Affects You. One Green Planet. https://www.onegreenplanet.org/animalsandnature/what-you-need-to-know-about-ocean-acidification-and-how-it-affects-you/.

[7] Jones, N. (2016, July 12). How Growing Sea Plants Can Help Slow Ocean Acidification. Yale Environment 360. https://e360.yale.edu/features/kelp_


[8] Laycock, A. (2018, September 12). Walking Drastically Cuts Your Carbon Footprint – And Helps Your Waistline. Blue and Green Tomorrow. https://blueandgreentomorrow.com/environment/walking-drastically-cuts-carbon-footprint-helps-waistline/

Nicole Vuong, U-Turn The Earth, 11 September 2020. Article.

1 Response to “Ocean acidification: a [pH]ishy dilemma”

  1. 1 hastidessa 19 October 2020 at 11:05

    Note that the terminology used in this article is misleading. The definition of “acidic” in the Oxford English dictionary is “having the properties of an acid; having a pH of less than 7″. Despite the process of ocean acidification, the oceans are alkaline (pH higher than 7) and will not become acidic in the foreseeable future. Hence, “acid” or “acidic” should not be used when referring to seawater. Note that there are few exceptions, seawater can be acidic in the immediate vicinity of CO2 vents or in purposeful perturbation experiments.

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