Climate change is undeniably one of the most significant consequences of human activities on the environment. Increasing greenhouse gas emissions, energy consumption, and deforestation have accelerated the warming of the Earth’s atmosphere and the ocean. The ocean is an essential natural resource that supports life on Earth, and it is affected by climate change in various ways. As the ocean absorbs more and more carbon dioxide (CO2) and other greenhouse gases, it becomes warmer and more acidic. This article will explore the impact of climate change on marine ecosystems, including sea-level rise, ocean acidification, and changes to marine biodiversity.
Rising Sea Levels:
One of the most apparent impacts of climate change is the rise in the Earth's global sea levels. This phenomenon is caused by melting ice caps and glaciers. The polar ice caps in Antarctica and Greenland store about 30 percent of the Earth’s freshwater; when they melt, they raise the sea level. The increased volume of water in the ocean poses a significant risk to coastal habitats and human populations as floods, and storm surges become more frequent, intense, and extended.
Marine organisms and ecosystems are also affected by the rise in sea level. Low-lying areas such as salt marshes, mangroves, and other coastal wetlands are particularly vulnerable to this effect. These ecosystems are vital for nutrient cycling, habitat provision, and shoreline stabilization. As sea levels continue to rise, the area of coastal habitats with sufficient tidal inundation for the survival of these plants will shrink, leading to their loss.
Additionally, rising sea levels can increase sedimentation and nutrient inputs from the land to the ocean, leading to unpredictable and severe impacts on the ecological balance in coastal environments. Low-lying islands and coral reefs are also at heightened risks due to the loss of protective habitats and increased exposure to wave energy caused by more frequent and severe storms.
Ocean Acidification:
The oceans absorb about 26 percent of CO2 emissions from human activities, reducing the amount of CO2 that would otherwise remain in the atmosphere. However, the uptake of CO2 by the oceans has a detrimental impact on marine ecosystems. When carbon dioxide is absorbed by seawater, it reacts to form carbonic acid, which gradually lowers the pH of the ocean resulting in ocean acidification. Since the Industrial Revolution, there have been significant increases in atmospheric CO2, causing a decrease in oceanic pH by approximately 0.1 units, representing a 30 percent increase in the number of hydrogen ions in the ocean.
Ocean acidification affects the formation of shells and skeletons made of calcium carbonate of many marine organisms. The amount of carbonate in seawater that is available for organism’s calcium carbonate shell formation decreases as pH decreases. This effect is potentially devastating to calcifying organisms, such as corals, shellfish, and plankton. These organisms play a vital role in carbon storage and nutrient cycling, making their decline irreversible and may have cascading effects on other organisms in the ecosystem.
In addition to the endangered species, ocean acidification also threatens the livelihoods of those depending on fishery and aquaculture industries. The decrease of populations and size crab fisheries, for example, have been observed since the 1980s. These affect the economies of many countries relying on these industries. Thus, mitigation and adaptation policies are necessary to help these communities.
Changes to Marine Biodiversity and Ecosystems:
The impact of climate change on marine biodiversity is becoming more evident each day. Due to increases in temperature, organisms migrate to escape their natural habitats, seeking cooler waters. Some examples include coral bleaching, changes in ocean currents, and shifts in sea temperatures, which have led to migration, changes, or loss of species.
Coral reefs are especially vulnerable to temperature and acidification changes, and the loss of these ecosystems is a significant contributor to the biodiversity loss. It is predicted that, due to ocean acidification and warming, coral reefs will decline by up to 90 percent by 2050. This is disastrous for many marine species, including fish that rely on coral reefs for food or protection.
Marine ecosystems play an essential role in sustaining human life, but they are changing rapidly as a result of human activity. Climate change has been shown to cause significant damage to oceans around the world through rising sea levels, ocean acidification, and changes to marine biodiversity. These changes threaten our security, livelihoods, and economic systems, and it is vital to implement strategies to protect our oceans and marine ecosystems. Thus, adaptation policies, reducing carbon emissions, and protecting marine biodiversity can help save our oceans' ecosystems.