Shah EMMA Perseverance CO2
The Other CO2 Problem: Silent Threat of Our Oceans
You know of many fictional evil twins— Raquelle and Ryan, The Grady sisters, etc. but do you know of one such duo present in our world? Meet Ocean Acidification, the equally evil twin of global warming.
The term ‘Ocean Acidification’ was first coined in 2003. It simply means the reduction in pH level of oceans caused by excessive intake of carbon dioxide (CO2) from the atmosphere. Like global warming, this is a direct consequence of increasing levels of carbon dioxide in the atmosphere. Let’s have a look at our antagonist’s origin story.
The ocean acts as a ‘carbon sink’ and takes in around 30 percent of the carbon dioxide released into the atmosphere by human activities, which majorly includes burning of fossil fuels. Fossil fuels are used regularly by us for powering our homes, vehicles, etc. Despite being called global warming’s twin, it is actually quite younger than its sibling. Scientists did not begin studying ocean acidification until recently when the changes caused by it began to be noticeable.
Let’s dive under the ocean and find out what exactly goes on there.
The CO2 absorbed by seawater reacts chemically with water, forming carbonic acid which then dissociates into bicarbonate and hydrogen ions. This increased amount of hydrogen ions makes the ocean more acidic by lowering the pH scale. The pH scale is a scale from 1-14 where 1 is very acidic and 14 is very basic or alkaline.
Since the industrial revolution 200 years ago, the ocean has absorbed around 525 billion tons of CO2 from the atmosphere and continues to absorb around 22 million tons everyday. At first scientists did not worry as they thought it was a good thing since it leaves less CO2 in the air. However, in the last few decades it has become clear that it is a matter of great concern. It was assumed that the rivers carried enough dissolved chemicals in them to stabilize the acidity, but the amount of carbon dioxide dissolving in the ocean is so high that this natural method of stabilizing, known as buffering, has not been able to keep up.
Ocean acidification, that is, increase in hydrogen ions is problematic for many organisms, especially shelled sea creatures, corals and more as such quick changes in ocean chemistry doesn’t give marine life, which evolved over millions of years much time to adapt. Creatures like shellfish and corals rely on carbonate ions to build their shells and skeletons. The hydrogen ions react with carbonate ions to form bicarbonate, leaving less availability of carbonate for these creatures.
They are then forced to spend more energy finding carbonate to build their shells, which leaves less energy for other activities such as reproduction. If there are too many hydrogen ions around and not enough molecules for them to bond with, they can even begin breaking existing calcium carbonate molecules apart—dissolving shells that already exist. Acidification gets piled on top of all the other stresses that coral reefs have been suffering from, such as warming water, coral bleaching, pollution, and overfishing.
Mussels and oysters are expected to grow less shell by 25 percent and 10 percent respectively by the end of the century. This means their shells will be weaker, making them vulnerable and increasing the chances of being crushed or eaten.
Fishes are sensitive to pH and even small changes would require them to put stress on their body to stabilize it. This would require burning more energy which in turn reduces the energy a fish has to take care of other tasks, such as digesting food, swimming rapidly to escape predators or catch food, and reproducing.
Some creatures are more resilient—like crustaceans. Studies have found that they grow even stronger shells under high acidity. Some, like purple sea urchins have already adapted to higher acidity.
Each species is built different biologically hence the effects of acidification are felt differently as well.
So does this mean humans are safe from the wrath of ocean acidification? Obviously, the answer is no. We can’t escape from the consequences of our actions. More than 3 billion people’s lives depend on oceanic resources, be it for food or livelihood. Ocean acidification greatly affects aquaculture and fisheries.
Well this makes it seem like an unsolvable issue. Is that true? The answer is also no. We might not be able to fully reverse the effects but we can surely minimize them, or atleast reduce them.
The best solution would be to stop our carbon dioxide emissions. However the amount of CO2 in the atmosphere is already so high that we would still need to pull CO2 out the atmosphere to try and mitigate the negative impacts of climate change. That’s easier said than done. What are the ways to possibly achieve this? One of the methods is Geoengineering.
It is the deliberate, large scale intervention in the biosphere and Earth’s natural systems to counteract climate change. One of the proposals include reflecting sunlight and thus excess heat, back into space from the atmosphere by putting huge reflecting mirrors in the orbit. Sounds unbelievable doesn’t it? However this solution does nothing to remove the CO2 present in the atmosphere.
Another soluttion is to remove carbon dioxide from the atmosphere by growing more of the organisms that use it up: phytoplankton. They would absorb carbon dioxide and after death sink down and trap it in the deep sea. This too has its limitations as it is not known how this will affect the food chain.
Yet another proposal is to add lime ( calcium hydroxide) in seawater to boost the ocean’s efficiency. This is so because lime is a strong alkali capable of neutralizing acids. For years, scientists have considered it a possible solution for increasing the alkalinity of seawater, and lowering the growing acidity level. As good of an idea it may be, it also has limitations. The process of mining limestone and extracting lime from it generates CO2 — if the point is to cut CO2 from the atmosphere, the solution itself shouldn’t contribute to the problem.
But hey, these are large scale solutions that a regular person cannot do. Is there something we can do on a small scale? The answer is yes! The best thing we can do is to try and lower how much carbon dioxide we use every day. This includes recycling, turning off unused lights, walking short distances instead of driving, using public transportation, etc.
Remember, we have no planet B. The earth is our home and responsibility. If we don’t save it, no one else will.
By: Sharvi Sonali
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