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Ocean Acidification

by Michelle Simon 23 Apr 2012
Ocean Acidification

Ocean acidification image via Shutterstock

If majority rule applied to all things natural, then the oceans would win the bid for status and recognition hands down, making up 71% of the planet, providing a habitat for 50% of all species, providing large volumes of oxygen and being the conveyor belt for climate. It was the production of oxygen in the oceans in prehistoric Earth that created the atmosphere and enabled diverse life.

The ocean is integral to life on earth, sustaining the atmosphere with moisture, keeping the planet cool enough, acting as a carbon sequester, ensuring the hydrologic/water cycle is constant and providing an invaluable protein supply to humans. It has taken humans just two hundred years to destroy the natural equilibrium that nature has established to keep the cycles going, the crisis disequilibrium we are facing is that of climate change, the human-induced radical changes to our climate system globally.

The Earth is a closed system, nothing exists in a vacuum, pollution emitted from a land-locked site, kilometres from the oceans will inevitably reach the oceans through the various interdependent cycles from the atmospheric cycle to the hydrologic cycle to biochemical cycle. Pollution released in one medium e.g. air emissions moves to other mediums such as soil and water and spreads across the globe.

Carbon dioxide (CO2) reaches the oceans through various industrial and agricultural sources; and is a top toxic green house gas (GHG). The main source being the fossil-fuel industry. The oceans CO2 levels were balanced prior to reckless human industrialisation without consequence, wreaking ecological havoc. It would seem that much of the polluting industrial technological choices and processes continue unabated.

Oceans as Carbon Sinks

"Over the past 200 years the oceans have taken up 500 GtCO2 from the atmosphere out of 1300 GtCO2 total anthropogenic emissions (IGOC, Unesco, 2007)." The pH of water in the ocean has been altered by a decrease of 0.1. pH indicates the level of acidity or alkalinity of liquid as represented on the scale of 0-14 (pH 0-6 = acid; pH 7 = neutral; pH 8-14 = alkaline). Scientists during the early days of climate change impacts, recognised the invaluable role of the oceans as sinks for CO2 but over time studies revealed how the oceanic environment is suffering due to this overload of CO2, altering the biochemistry and ecosystem functioning of the oceans. It is estimated that the oceans absorb about a quarter of CO2 emissions.

Chemistry of Ocean Carbon

Atmospheric CO2 reaches the ocean through precipitation, fallout, wind-blown particulate matter, in the ocean CO2 forms a chemical reaction with salt water, forming bicarbonate ions and carbonic acid. This creates irreparable damage to the ocean's pH balance, making it more acidic and thereby having a direct impact on pH dependent processes such as calcification. Calcium carbonate minerals, necessary for the formation of shells and skeletal structures of marine organisms are depleted, thus decimating species and having consequences for the entire marine food chain. This food chain extends to the terrestrial and ocean-land interface food chains where humans and bird life depend on the oceans as a direct food source.

Ocean Food Chain

Increased acidity in the ocean changes the ability of species to build the necessary physiological material needed to survive, shellfish need shells, marine animals require their skeletons as do we land animals. Can you imagine having your skeleton eroded with acid? Well that's exactly the painful reality been forced upon by humans on existing marine life-forms, let alone the reproductive and birth defects being suffered by new offspring due to the hindered calcification process arising from high content acid in the oceans.

What will be wiped out eventually? Corals - shallow and deep corals, the coral reefs. Coral reefs are a haven habitat for biodiversity, we have already destroyed them with marine development, ocean acidification will corrode and erode the reefs.

Shellfish - oysters, clams, mussels, snails. Snail species such as the vital pteropod, a winged snail species providing a food source for many commercial fish, has shown shell dissolution. Phytoplankton and Zooplankton - from single-celled to multi-celled organisms, these calcifying organisms will dwindle. Fish and Invertebrates species - may suffer from a impeding health impact called acidosis, which increases carbonic acid content in body fluid and blood, affecting immunity, altering physiological and reproductive health.

Similarly, as with human-induced climate change impacts, increased oceanic CO2 levels and acidification, are happening at such a rapid pace, that unlike prehistoric changes over million-year timelines whereby nature can evolve and adapt, human destruction is happening in the blink of evolutionary time.

Overfishing and environmentally destructive fishing methods have not only wiped out target fish species but also non-target species. Fishing methods such as trawling have caused untold damage to the diversity of the ocean floor habitats. The once undisturbed oceanic carbon sinks have come undone a while ago with interference to the ocean bed with drilling, dragging and mining extractions.

Carbon Dioxide Capture and Storage (CCS)

Like it isn't enough that we release tons of pollutants into the air, water and soil. We now want to 'inject CO2' into the ocean as a solution to the high-level atmospheric CO2. Manual injection of CO2 into the oceans is being proposed by industry and government as one of the bright plans to resolve the carbon crisis.

Do the environmental impacts of this further damage need to be spelt out? So, redirect our emissions and store them in the ocean floors at varying depths and what happens when a natural disaster or another intelligent human process like offshore drilling, releases all this concentrated CO2 back into the atmosphere?

What of the other high probability of the slow release injected-CO2 from those human created sinks into the ocean that is already acidic? How is redirecting pollution from one medium to another solving the crisis? The crisis lies with the dirty polluting technologies that we still use and our hard-headed refusal to radically transform our societies into dominant clean technology proponents with the urgency that this crisis warrants.

According to the US National Oceanographic and Atmospheric Administration (2011), estimates of future carbon dioxide levels, based on business as usual emission scenarios, indicate that by the end of this century the surface waters of the ocean could be nearly 150 percent more acidic, resulting in a pH that the oceans haven't experienced for more than 20 million years.

The impact of the altered natural chemistry of the ocean is dire for us, dire for marine ecosystems and the survival of marine animals. Once the link or several links of the chain are compromised, broken, destroyed, altered or minimised, the entire chain weakens and suffers. Nothing we do is without consequence and the sooner we realise this the better for all life-forms on the planet.

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