Ocean Pollution's Climate Change Impact: Understanding The Crisis

Oceans are a vital part of the global environment, regulating the climate and providing a home to millions of species. They cover 71% of the Earth's surface and make up 95% of the space available to life. However, human activities have led to ocean pollution, which has far-reaching consequences for marine life and the climate. The ocean has absorbed about 90% of the excess heat from rising greenhouse gas emissions, leading to unprecedented effects, including ice-melting, sea-level rise, marine heatwaves, and ocean acidification. These changes threaten marine biodiversity and the livelihoods of coastal communities, with the potential for devastating consequences if left unchecked.

Ocean acidification

When CO2 dissolves in seawater, it forms carbonic acid (H2CO3), releasing hydrogen ions (H+) and increasing ocean acidity. The increased concentration of hydrogen ions leads to a reduction in carbonate ions, which are essential for the growth and development of various marine organisms. These include clams, mussels, crabs, corals, and some types of plankton, which rely on carbonate ions to build their shells and skeletons.

Coral reefs, for example, are particularly vulnerable to ocean acidification. The process hinders their ability to recover from coral bleaching events, which are triggered by warm water temperatures. Ocean acidification reduces the amount of calcium carbonate available, which corals need to regenerate their skeletal structures. This double threat of warming waters and acidification puts coral reefs in grave danger, with projections indicating that up to 99% of warm-water coral reefs could disappear if global temperatures rise by 2°C or more above pre-industrial levels.

The impacts of ocean acidification extend beyond marine life to human communities as well. Coastal communities, aquaculture, and tourism are all at risk. It is estimated that up to three billion people who depend on marine and coastal biodiversity for their livelihoods could be impacted. Shellfish industries, for instance, face significant challenges due to the reduced availability of minerals needed for shellfish growth. A study in the United States projected that the country's shellfish industry could lose more than US$400 million annually by 2100 due to ocean acidification.

Addressing the root cause of unabated CO2 emissions from the burning of fossil fuels is crucial to mitigating the effects of ocean acidification. By reducing carbon emissions and adapting to climate change, we can help protect marine ecosystems and the communities that rely on them.

Extreme weather events

The ocean regulates the global climate, influencing temperature, weather, and rainfall patterns. As the planet warms due to climate change, the ocean absorbs excess heat and energy, leading to a range of cascading effects, including the melting of polar ice, rising sea levels, marine heatwaves, and ocean acidification. These changes have far-reaching consequences for marine biodiversity and human communities, including the approximately 680 million people living in low-lying coastal areas and the nearly 2 billion in coastal megacities.

One of the key impacts of climate change on the ocean is the increase in extreme weather events, such as:

• Hurricanes and Storms: Storm systems, including hurricanes, derive their energy from warm ocean water. As global temperatures rise, these storms are becoming more intense and are intensifying faster. For example, in September 2024, Hurricane Helene caused historic flooding in the Southeast United States, leading to fatalities and power outages. Warmer ocean waters also contribute to the formation of tropical cyclones, which, in combination with rising sea levels, can lead to deadly storm surges, coastal flooding, erosion, and landslides.
• Wildfires: Climate change, particularly in hotter and drier regions, contributes to larger and more intense wildfires. The smoke from these fires creates hazardous air pollution that can spread over vast areas, affecting the health and well-being of millions of people.
• Heatwaves: Rising global temperatures result in more frequent and severe heatwaves. These events pose significant health risks and strain energy systems due to increased demand for air conditioning. Extreme heat also contributes to droughts by accelerating moisture evaporation from water bodies and soil, leading to drier conditions.
• Floods: Warmer ocean waters and melting land ice contribute to rising sea levels, which, in combination with heavier precipitation, increase the risk of flooding. Coastal regions are particularly vulnerable to the impacts of rising sea levels, with some areas experiencing historic flooding events and storm surges.
• Winter Storms: Climate change can contribute to more extreme winter weather patterns. As the atmosphere warms, it traps water vapor, leading to heavier snowfall when temperatures drop. Additionally, the warming of the Arctic region may be disrupting the polar vortex, resulting in cold air escaping southward and causing freezing winters in some regions.

The increasing frequency and intensity of these extreme weather events highlight the urgent need to address the root causes of climate change, reduce carbon emissions, and adapt to changing environmental conditions.

Rising sea levels

The impact of rising sea levels is already being felt by both wildlife and human populations. In the United States alone, there are 1,383 federally protected threatened and endangered species, many of which depend on coastal and island habitats for their survival. As sea levels rise, these habitats are at risk of being submerged and eroded, and the resulting increase in groundwater salinity can kill coastal plant communities and contaminate drinking water sources.

One of the most vulnerable species is the Hawaiian monk seal, which is endemic to Hawaii and is already among the most endangered seal species globally. The loss of suitable habitats for giving birth, such as beaches and low-lying islands, poses a critical threat to the survival of this species. Beach erosion from storm surges and sea-level rise have already led to the disappearance of one of their breeding islands.

Another species at risk is the Florida Key deer, which inhabits a string of low-lying islands south and west of Miami. With an elevation of less than three feet above sea level, their habitat is highly vulnerable to rising sea levels. While Key deer are strong swimmers, they are not adapted to survive if their terrestrial habitat is inundated by rising seas.

The impact of rising sea levels extends beyond wildlife, as coastal communities and human settlements are also at risk. Approximately 680 million people live in low-lying coastal areas worldwide, and nearly 2 billion people reside in half of the world's megacities, which are coastal. As sea levels rise, these areas face increased risks of deadly storm surges, flooding, erosion, and landslides, which are projected to occur more frequently and with greater intensity.

To address the challenges posed by rising sea levels, urgent action is needed to mitigate climate change and protect vulnerable species and communities. This includes reducing greenhouse gas emissions, safeguarding natural coastal buffers, and providing wildlife with the necessary space to move inland as sea levels continue to rise.

Loss of marine biodiversity

The ocean is home to millions of species, and its health is strongly dependent on marine biodiversity. Climate change due to human activity has a direct impact on marine life, altering their abundance, diversity, and distribution. Their feeding, development, and breeding, as well as the relationships between species, are all affected.

Rising temperatures cause different behavioural patterns in species. Some adapt to temperature changes, while others migrate towards the poles or new areas. Other species, such as certain corals, disappear as they can rapidly bleach and die when their symbiosis with unicellular algae is interrupted. Corals are home to many sea creatures, and when the water is too warm or too cold, they become damaged in a process called bleaching. If bleaching continues for too long, it can kill the coral. Coral reefs are also dying off due to ocean acidification, which is caused by the increasing absorption of atmospheric carbon dioxide. This process increases acidity levels, and when combined with warming oceans, it creates an unhealthy habitat for the species that rely on them for food and protection.

The loss of marine biodiversity weakens the ocean ecosystem and its ability to withstand disturbances, adapt to climate change, and play its role as a global ecological and climate regulator. As the ocean ecosystems become depleted, they become less able to adapt to climate change. This loss of biodiversity also implies a loss of genes and molecules that are potentially valuable for medical research and industry.

Marine environments are incredibly diverse ecosystems, even more so than tropical rainforests. However, they are subject to multiple stressors, including human activities, pollution, land use, and development along coastlines, which can impact their sustainability and biodiversity. Biotoxins linked to harmful algal blooms, known as "red tides", have been implicated in the widespread mortality of marine mammals and fish. These blooms are linked to increasing temperatures in the Atlantic and Pacific Oceans. As these blooms occur, they deplete oxygen levels, making it harder for other organisms to survive.

Overall, the loss of marine biodiversity has far-reaching consequences, affecting not only the health of the oceans but also the lives of millions of people worldwide.

Coral bleaching

Coral reefs are among the most threatened ecosystems on Earth, largely due to unprecedented global warming and climate changes. Coral bleaching occurs when reefs lose their life-sustaining microscopic algae when under stress from rising ocean temperatures. A spike of 1-2°C in ocean temperatures sustained over several weeks can lead to bleaching, turning corals white. If corals are bleached for too long, they will eventually die.

Coral reefs harbour the highest biodiversity of any ecosystem globally and directly support over 500 million people worldwide, mostly in poorer countries. They provide a wide variety of ecosystem services such as subsistence food, protection from flooding, and support for the fishing and tourism industries. Their disappearance will therefore have economic, social, and health consequences.

Over the last three years, reefs around the world have suffered from mass coral bleaching events as a result of the increase in global surface temperature caused by anthropogenic greenhouse gas emissions. The Great Barrier Reef in Australia and the Northwestern Hawaiian Islands in the United States have experienced their worst bleaching on record, with devastating effects. The bleaching of the Great Barrier Reef in 2016 and 2017, for instance, killed around 50% of its corals.

According to UNESCO, the coral reefs in all 29 reef-containing World Heritage sites would cease to exist by the end of this century if we continue to emit greenhouse gases under a business-as-usual scenario. Scientists estimate that if the current rates of temperature increase continue, the oceans will become too warm for coral reefs by 2050.

To prevent this, limiting global average temperature to well below 2°C above pre-industrial levels in line with the Paris Agreement is crucial for the survival of coral reefs. Additionally, local actions such as reducing single-use plastics and banning chemical sunscreens can help protect corals and have wide-ranging benefits for the ocean ecosystem.

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