The oceans are more acidic today than they were 100 years ago mainly due to the increase in carbon dioxide emissions in the atmosphere. Some of this CO2 is absorbed by the oceans, leading to an increase in water acidity, a process called ocean acidification.
Since the industrial revolution, a huge amount of carbon dioxide (CO₂) has been released into the atmosphere. This mainly comes from the burning of oil, coal, or gas to produce energy, heat our homes, or power our cars. But when we burn all these fossil fuels, the CO₂ released does not remain solely in the air. A large portion eventually ends up in the oceans, which seriously disrupts the natural balance. As a result: the more air pollution there is, the more the oceans become acidic.
Oceans naturally absorb a large portion of the carbon dioxide (CO₂) present in the atmosphere. Since the industrial revolution, our activities (industry, transportation, agriculture...) have released much more CO₂ into the air. As a result, the oceans must absorb more. Today, it is estimated that about a quarter of the carbon dioxide produced by humans ends up directly in ocean water. Naturally, this disrupts the natural balance. This excessive absorption leads directly to an increase in ocean acidity, known as ocean acidification, an environmental issue that has become significant in the past hundred years.
Oceans naturally absorb a large part of the carbon dioxide (CO₂) present in the atmosphere, acting like a giant sponge. Once in the water, CO₂ does not remain as it is; it quickly forms carbonic acid. This acid then decomposes into bicarbonate ions and hydrogen ions. And it is precisely the accumulation of these hydrogen ions (H⁺) that makes the water more acidic by lowering its pH. As a result, the water becomes less welcoming to many marine organisms, particularly those that build their shells and skeletons from calcium carbonate, a substance highly sensitive to acid.
Ocean acidification directly disrupts certain marine organisms, especially those with shells or calcium skeletons such as corals, mollusks (oysters, mussels), and some plankton. These species struggle to build and maintain their shells or calcium skeletons in an environment that has become too acidic. As a result, coral reefs are bleaching, declining, and the entire ecosystem that depends on them (fish, crustaceans, turtles, etc.) is severely weakened. Less visible changes also affect small organisms in marine plankton, which are essential for the proper functioning of food chains. And when the foundations of the food pyramid wobble, the entire marine biodiversity suffers.
One of the main avenues is to reduce CO₂ emissions, particularly from fossil fuels, by focusing on cleaner energy sources like solar or wind. The less greenhouse gases we produce, the less the ocean has to absorb—it's logical. We can also protect and restore certain coastal ecosystems, such as mangroves or seagrass beds, which naturally capture carbon. Some techniques even propose to directly remove CO₂ from the atmosphere, but it's still somewhat experimental. Finally, better management of marine areas by setting fishing quotas or creating marine reserves helps ecosystems better withstand acidification.
Ocean acidification could influence the behavior and survival of fish by disrupting their sensory abilities, such as smell, thereby impacting their ability to find food and avoid predators.
Since the beginning of the industrial revolution, the average pH of the oceans has dropped by about 0.1 units, which may seem small at first glance but represents an increase of about 30% in their acidity.
The increased acidity of the oceans can make it more difficult for certain marine organisms, such as corals and shellfish, to build and maintain their shells, which are primarily composed of calcium carbonate.
Some marine regions, particularly off the west coast of the United States, are already experiencing seasonal episodes of extreme acidification, creating significant challenges for the local seafood industry and the marine ecosystem.
Sure! Here is the translation: "Yes, certain regions, such as the Arctic and some coastal areas, experience more pronounced acidification. For example, cold waters absorb more CO₂ and are therefore naturally more sensitive. Similarly, regions affected by significant runoff due to human activities can also experience locally higher rates of acidification."
These two phenomena stem from the same main factor: excessive greenhouse gas emissions, particularly carbon dioxide (CO₂), which is primarily produced by human activities. While atmospheric CO₂ leads to global warming, the CO₂ absorbed by the oceans causes their acidification, making these two processes interdependent.
Sure! Here’s the translation: "Yes, ocean acidification can disrupt marine ecosystems and directly affect the fish and seafood we consume. By impacting the growth and survival of key species, such as crustaceans and mollusks, it threatens commercial fisheries and global food security."
We cannot completely halt the current acidification instantaneously, but it is possible to significantly slow it down by reducing our global CO₂ emissions, improving waste management, and enhancing the quality of coastal waters. Technological solutions, such as carbon capture and sequestration, as well as the restoration of marine ecosystems (mangroves, seagrass beds), are also promising approaches.
Among the observed signs, there is a progressive weakening or dissolution of the shells of calcareous marine animals (shellfish, corals), increased difficulties in building solid coral reefs, as well as a general disturbance in marine ecosystems and the food chain.
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