Climate Change And Ocean Acidification

by | Jul 9, 2024 | Climate Change

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Climate change and ocean acidification are among the critical environmental challenges faced by this globe. Primarily being caused by greenhouse gas emissions, the effects seem quite evident in marine ecosystems—on fish populations and biodiversity. Warming and acidification alter marine life’s characteristics negatively, affecting biodiversity levels and, by extension, the aquatic resources and the human livelihoods that depend on them. It is only this high time that the interrelation of climate change and ocean acidification is recognized for the engendering of strategies that will mediate this catastrophe.

Understanding Climate Change and Ocean Acidification

Climate change and ocean acidification are widely recognized today as two critical concerns to modern civilization. They constitute self-reinforcing environmental issues that work in interconnected ways to change marine systems and the global climate at large.

What is Climate Change?

Climate change is a term applied to the large, long-term variations in Earth’s climate and weather systems. The total temperature has increased by about 1.1°C since the late 19th century [Source: NASA Earth Observatory]. Human activities leading to increasing emissions of CHGs, mainly CO₂, CH₄, and N₂O, are primarily responsible for changes in climate. CO₂ content in the atmosphere has gone up from pre-industrial levels of 280 ppm to about 415 ppm by 2023. [Source: Statista]

What is Ocean Acidification?

Ocean acidification is the ongoing decrease in the earth’s oceans’ pH driven primarily by the uptake of atmospheric CO₂. The arithmetical value of pH at the ocean’s surface has decreased by about 0.1 units since the Industrial Revolution, reflecting an increase of 26% in acidity [Source: Wikipedia]. When CO₂ is absorbed by seawater, it reacts with water to form carbonic acid, which lowers the pH and the concentration of carbonate ions that marine organisms require to build shells and skeletons. Assuming current CO₂ emission rates are maintained, it is estimated that pH could decrease another 0.3 to 0.4 by the end of the century [Source: AWI].

Also Read: Pollutants In The Ocean: Identifying Sources And Solutions

Impacts of Climate Change and Ocean Acidification on Marine Ecosystems

Altered through and through, world marine ecosystems never remain the same when climate change and ocean acidification take the floor. These changes concern a wide range of marine species and habitats and may have large implications for biodiversity, fisheries, and coastal communities.

1. Coral Reefs

1.1. Climate Change Impacts

  • Warmer oceans’ temperatures heat up, purging,  a process whereby corals eject zooxanthellae algae, which leaves its tissue. One most recent case in point is the Great Barrier Reef, which faced monumental bleaching events during 2016 and 2017. The bleaching during these two events cuts the reef to 50%. [Source: The Australian Institute of Marine Science]
  • Increased sea levels support sedimentation and turbidity, and as a consequence, they do not allow sunlight to the corals and other photosynthetic organisms the required sunlight. [Source: BOQU]

1.2. Ocean Acidification Impacts

  • Calcium carbonate is used to build coral skeletons. Acidification will, therefore, naturally slow the rate at which coral skeleton growth increases. The latest studies have shown that with a single decrease in pH unit, there can be a physiologic slowing rate for coral calcification that ranges from 10% to 30%. [Source: NIH]
  • Weakened coral skeletons are more fragile and can be more readily broken and eroded. This breaks the reef and can weaken the habitat for other animals there. [Source: Woods Hole Oceanographic Institution]

2. Marine Biodiversity

2.1. Impact on Shellfish

Many shellfish species, including oysters, clams, and mussels, rely on carbonate to form their shells. For instance, the results of acidifying waters are now reported to have killed many of the larvae of a number of species in the oyster population of the Pacific Northwest. [Source: Life at OSU]

2.2. Impact on Plankton

  • Calcification will decrease its abundance and alter its species composition, thus resulting in an ecosystem-wide cascade. [Source: The National Academies Press]
  • Zooplankton, their predators, result in the changed abundance of plankton. Subsequently, all the marine fish animals whose standard food source is zooplankton are also affected. [Source: IntechOpen]

2.3. Impact on Fish

  • Many species of fish move toward higher latitudes to remain within their optimal temperature conditions. This movement results in new relationships between species and competition that alter ecosystems.
  • Atlantic cod exhibited reduced hatching success as well as larval survival in warmed and acidified conditions. [Source: NOAA Fisheries]

3. Fisheries and Coastal Communities

3.1. Economic Impacts

  • As fish stocks migrate and decline due to changing oceans, the fishing industry may harvest smaller catches, leading to economic losses. Hundreds of millions rely on this global industry for a livelihood, while billions rely on it as a basic protein source. [Source: FAO]
  • On the US Pacific Northwest coast, oyster hatcheries have recently reported high failure rates of larval production due to increased ocean acidification. [Source: National Science Foundation]

3.2. Food Security

  • If the marine food chains get disrupted or the level of stock becomes reduced, it can adversely affect food security and nutrition. [Source: World Wildlife Fund]

4. Marine Habitats and Ecosystem Services

4.1. Mangroves and Seagrasses

Mangroves and seagrasses play a significant role in coastal protection and carbon storage. They could be affected by climate change. Seagrass growth and health are also impacted by ocean acidification, although some of the studies noted that seagrasses may have the capacity to offset local acidification impacts through photosynthesis. [Source: The National Academies Press]

4.2. Wetlands and Estuaries

Respiration in wetlands and estuaries is also responsible for much of the nutrient cycling and supports a great number of species. Alterations in these ecosystems, which can be changed by variations in salinity and temperature in wetlands, may ultimately change species composition and ecosystem function. [Source: Nature]

The impacts of climate change and ocean acidification on marine systems are deep and multifarious. Mitigating these crises may secure the key services that marine ecosystems provide for human beings.

Mitigation and Adaptation Strategies

Effective mitigation and adaptation, therefore, can help in the fight against these twin menaces: climate change and ocean acidification. Proper proactiveness would safeguard these marine ecosystems and guarantee a festive future for coastal communities.

Climate change and ocean acidification

Effective mitigation and adaptation require and can be achieved through cooperation with global and innovative solutions. We can mitigate the impacts through worldwide collaboration and innovative solutions.


Climate change and ocean acidification have made contemporaneous threats to marine ecosystems’ health globally. Only through reduced greenhouse gas emissions and adaptive management could such adverse effects be mitigated or harnessed to avoid any damage to ecological diversity and human survivability. More such research is needed, primarily requiring international cooperation. This is the only way to strive toward viable solutions that will guarantee, for generations to come, the health of marine ecosystems and the benefit of biodiversity to be conserved over time with such important services they have to offer humanity.

Also Read: The Impact Of Rising Ocean Levels On Fisheries And Global Food Supply



  • Dr. Emily Greenfield

    Dr. Emily Greenfield is a highly accomplished environmentalist with over 30 years of experience in writing, reviewing, and publishing content on various environmental topics. Hailing from the United States, she has dedicated her career to raising awareness about environmental issues and promoting sustainable practices.

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