I. The Acidification of the Oceans Fr. Seán McDonagh, SSC December 6, 2010

I. The Acidification of the Oceans

Fr. Seán McDonagh, SSC

The wonder of the oceans

The oceans have a very special place in the story of the Universe. To many of us, they are just there and seem ordinary and common place. But we can truly appreciate their significance when we view them as a special aspect of the unfolding of the universe itself. As far as we know, liquid water is found nowhere else in the Universe. Water vapor and ice has been found on other planets, but only on planet Earth have the oceans been created and maintained in their liquid form for four billion years. Oceans were probably on the Red planet (Mars), but they have long since vanished. Oceans cover three-quarters of the entire surface of the planet.

Furthermore, the oceans are the womb of life. For almost 2 billion years, bacteria were the only forms of life on earth. During the first billion years, the blue-green algae learned how to take hydrogen from the oceans and to release oxygen into Earth’s carbon-dominated atmosphere. This was the beginning of photosynthesis. The oceans are home to the largest creature on the planet – the blue whale – and also the largest living entity on the planet – the Great Barrier Reef, which is located off the Eastern coast of Australia.

The oceans also pay a vital role in climate, somewhat like the Earth’s lungs and circulatory system – by generating oxygen, absorbing carbon dioxide and regulating climate and temperature.  The oceans have absorbed 80% of the heat which has been added to the climate system and nearly 50% of all the CO2 which has been added to the atmosphere by burning fossil fuel during the past 250 years, since the beginning of the industrial revolution.

More serious disruption than sea-level rising

Many people are now aware that the increased levels of CO2in the atmosphere are warming the planet and thus contributing to the rise in the ocean levels through thermal expansion and through melting glaciers in the Antarctic and Greenland. This will have a profound effect on how humans live in the future as more than 50% of the human population lives in 183 coastal countries, including 44 small island nations whose very future as countries is in the balance as ocean-levels rise.

But something else is also happening about which few people are aware. About one quarter to one third of the CO2 ends up in the oceans, where it dissolves to form carbonic acid, and then dissociates into bicarbonate and hydrogen ions. The more hydrogen ions there are in the water, the lower its pH is. In other words, it is more acidic. Furthermore, the excess of hydrogen ions react with, and eliminate carbonate ions, which are necessary for the formation of calcium carbonate skeletons and shell production in many species of marine organisms. Scientists have found that there are less carbonate ions in the ocean now than at any other time in the past 800,000 years.

Normally the surface waters of the oceans are slightly alkaline with a pH greater than 7. However, because they are absorbing more CO2, the oceans are about 30% less alkaline today than they were before the industrial revolution. The consequences of this are very significant and worrying on a number of fronts. Less alkaline water reduces the availability in seawater of carbonate minerals such as calcite and aragonite. These minerals are important in the formation of corals, shellfish, marine plankton and fish skeletons. The physiology, development and even survival of these creatures are thereby threatened.

During my years in the Philippines, I enjoyed regularly snorkeling in coral reefs. I also became aware of the importance of corals for marine life and the people who fished the reefs. Over the years, I began to learn something about the extraordinary biological diversity in coral reefs. Studies have shown that that at least one quarter of the biodiversity of the oceans are found in coral reefs. Because of their wealth in species, coral reefs they are often referred to as the rainforests of the ocean.

They are very important for humans also. It is estimated that world-wide, 500 million people depend on corals reefs for coastal protection, food, tourism and other forms of income. Economists estimate that reefs and their products are worth between US$30 and $172 billion per annum. In Hawaii alone, for example, the tourism generated by the coral reefs brings in US $364 million per annum.

This is all under threat from ocean acidification. Since 1990, skeletal growth on the Great Barrier Reef off the east coast of Australia was down by 14%. This is the largest stunted growth level in the past 400 years. In an increasingly acidic ocean, coral reefs will decline and may even become extinct.[1] It is estimated that 4,000 species of fish depend on coral reefs. Reefs are marine nurseries, providing food, shelter and a safe haven from predators. The dwindling corals are already impacting on a number of species of fish, leading to the extinction of some species.


Pteropods are tiny swimming sea snails which are abundant in the oceans. There are often thousands of individual snails per cubic metre.[2] They are an important element in the marine food chain as they form the diet of zooplankton, salmon, herring, and baleen whales. The question is will they thrive in increasingly acidic oceans because their calcium carbonate shells may not develop properly. Some predict that as early as 2050; pteropods may be unable to form shells which would threaten their own survival and the species which depend on them.[3]

Other species will benefit from higher levels of carbon dioxide in the oceans. The problem is that these species are currently seen as nuisance or weedy species. Top of the list are jellyfish. Scientists are not clear yet whether the increased prevalence of jellyfish is as a direct result of ocean acidification. Jellyfish blooms could have a disastrous impact on other species and on the oceans in general. They also will impact on tourism, as no one likes to be stung by a jellyfish while swimming in the ocean.

If the oceans become more acidic there will be a serious decline in biodiversity, thereby affecting a whole raft of species, including humankind as the oceans are less able to supply us with food. Reducing GHG gas emissions, especially CO2 is not just important in tackling climate change, it is also necessary if we want to protect the fruitfulness of our oceans on which we all depend.

The oceans do not figure prominently in our Judeo-Christian tradition about the oceans, mainly because the Israelites were not a sea-faring nation. In many ways the oceans were perceived as dark danger, mysterious and dangerous places.  At the beginning of the Book of Genesis (1: 1-2) we find God’s spirit hovering over ‘the void’ and ‘the deep’.  The author of the  Book of Genesis reworks the Babylonian creation myth Enuma Elish which describes how the gods  brought order out of the original chaos. The author of Genesis did not need a pantheon of gods and goddesses to achieve his goal. For him God had the power to tame the elements, especially the unpredictable oceans. This taming the oceans is found in  many passages in the Hebrew scriptures.  In the book of Job God asks Job:

Who pent up the sea behind closed doors when it

leaped tumultuous out of the womb,

when I wrapped it in a  robe of mist –

and made black clouds its swaddling bands;

when I marked the bounds it was not to cross

and made it fast with a bolted gate.

Come thus far and not farther;

Here your proud waves will break (Job 38: 8 – 11).

The fearsome nature of the ocean and the dangers facing seafarers riding in fragile boats is described in graphic terms in Ps. 107: 25 to 27).

He spoke and raised a gale, lashing up towering waves

Flung to the sky, then plunged to the depths, the lost

Their nerve in the ordeal, staggering like drunkards

With all their seamanship adrift.

There are also positive reference to the oceans in the Bible.  In Ps. 69:34, “the oceans and all that move in them are called to praise God.


As Christians living in a world where the oceans are under threat from human activity, we need to develop this positive strand in the biblical teaching in order to reshape a theology of the oceans which will help us to protect the seas in our modern world.

We have much to learn from other traditions. Writing in this paper (December 26th 2010), John Battle describes some elements in the theology of Bishop Winston Halapua who was born in Tonga and now lives in Fiji.  Battle wrote, “his theology of the centrality of the oceans, called Theo-moana’ (moana is the ancient Polynesian word for ocean). He uses the concept God-ocean to insist on the dynamic interconnectedness and engagement of life as a whole.[4] In his book Waves of God’s Embrace: Sacred Perspectives from the Ocean the bishop shapes his theology by reflecting on five ocean values – hospitality, identity, unity in diversity, sharing stories and sharing gifts. Such a theology has a universal resonance in our contemporary world.




[1] Hoegh-Gudberg, O …et all (2007) Coral reefs under rapid climate change and ocean acidification. Science, 318 (5857); 1737-1742.

[2] Doney, S., Fabry, V. Feely, R., Kleypas, J. (2009) Ocean Acidification: The Other CO2 Problem, Annual Review of Marine Science, 1:169-92


[3] Orr, J.C., et al. (2005) Anthropogenic ocean acidification over the twenty-first century and the impact on calcifying organisms, Nature, 437-:681-686.

[4] John Battle, “We must place the oceans in the centre of our  plans,” The Universe, December 26th 2010, page 29.


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