Ocean Pollution's Impact On Climate Change

Marine pollution and climate change are not separate issues. The ocean is the planet's greatest carbon sink, absorbing about 90% of the heat generated by rising emissions. However, the ocean is now a victim of human-made global warming, with plastic waste being a key contributor. As plastic breaks down, it releases methane and CO2, and microplastics affect the ability of marine organisms to absorb carbon dioxide. This creates a negative feedback loop where plant and animal life suffer, less carbon dioxide is absorbed, and our ability to rein in climate change is further hampered.

Plastic waste in oceans releases methane and CO2 as it breaks down

Plastic waste in oceans is a significant contributor to climate change. As plastic breaks down, it releases methane and carbon dioxide (CO2), which are greenhouse gases. This process, known as degradation, has a catalytic role in global warming. At all stages of degradation, plastic emits these harmful gases. For example, when heated by the sun, plastic undergoes photodegradation, producing ethylene and methane, a gas 21 times more potent than CO2. As microorganisms metabolize plastic, they convert the carbon in nano-plastics into CO2. The smaller the plastic particles become, the more greenhouse gases are produced.

The impact of plastic on the climate is often overlooked, with many assuming that plastic is only detrimental to the environment because it does not degrade. However, the degradation of plastic is a significant issue. Dr. Sarah-Jeanne Royer, an oceanographer, has studied the effects of plastic in the sea and found that it directly contributes to the increase in greenhouse gas concentrations in the atmosphere.

The production of plastic is also a concern. As the demand for plastic increases, so does the use of fossil fuels, which leads to a larger carbon footprint. The manufacturing of plastic contributes to greenhouse gas emissions, and as plastic production increases, we will use more fossil fuels, further intensifying the climate crisis.

The presence of plastic in the ocean is continuously increasing, and it is one of the main causes of marine species extinction, health problems for humans and animals, and ecosystem destruction. It is estimated that by 2050, plastic will outweigh all fish in the sea.

To combat this issue, we must transition from a single-use society to a circular economy, reducing our use of harmful chemicals and disposable plastic items. Additionally, improving waste management systems and implementing recycling practices can help prevent plastic waste from entering rivers and seas.

Marine heatwaves caused by ocean warming are becoming more frequent, longer-lasting, and intense

Marine heatwaves, defined by the IPCC as "a period during which water temperature is abnormally warm for the time of the year relative to historical temperatures, with that extreme warmth persisting for days to months", are becoming more frequent, longer-lasting, and intense due to ocean warming. This warming is caused by the ocean absorbing about 90% of the excess heat generated by rising greenhouse gas emissions.

The increase in the frequency, duration, and intensity of marine heatwaves is confirmed by the IPCC Sixth Assessment Report in 2022, which states that "marine heatwaves are more frequent, more intense, and longer since the 1980s, and since at least 2006 are very likely attributable to anthropogenic climate change". The report predicts that marine heatwaves will become "four times more frequent in 2081-2100 compared to 1995-2014" under a lower greenhouse gas emissions scenario, or eight times more frequent under a higher emissions scenario.

The impact of marine heatwaves on oceanographic and biological conditions can be drastic and long-term. For example, the marine heatwave in the Northeast Pacific from 2013 to 2016, known as "The Blob", led to an ecological cascade, causing fishery collapses and fishery disaster determinations. It also caused whales' prey to be concentrated unusually close to shore, and a severe bloom of toxic algae along the coast delayed the opening of the valuable Dungeness crab fishery.

The increase in the frequency and intensity of marine heatwaves is expected to have drastic implications for the distribution of species. Changes in the thermal environment of marine organisms can cause habitat degradation, changes in species range dispersion, and contribute to mass mortality. For example, the 2015-2019 marine heatwaves in the Mediterranean Sea resulted in widespread mass die-offs of sealife for five consecutive years.

The prediction for the future is that marine heatwaves will continue to increase in frequency, duration, and intensity as sea surface temperatures continue to rise with global warming.

Microplastics affect marine organisms' ability to absorb CO2 and release oxygen

Marine organisms, such as phytoplankton and bacteria, play a crucial role in the carbon cycle and oxygen production. Phytoplankton, through photosynthesis, produces sugars and oxygen from sunlight and carbon dioxide (CO2). Bacteria, on the other hand, consume these sugars and release CO2 back into the water, the sea surface, and eventually the atmosphere. This process, known as the biological carbon pump, is responsible for storing a significant proportion of carbon in the ocean, making it Earth's largest natural carbon store.

However, the presence of microplastics in the ocean can disrupt this delicate balance. Microplastics, which are small plastic particles (<5 mm) that originate mostly from human activities, float on the sea surface and persist in the marine ecosystem. Their microscopic size makes them easily ingestible by a range of marine organisms, including phytoplankton and bacteria. Studies have shown that exposure to microplastics can alter photosynthesis in phytoplankton and reduce feeding rates in zooplankton, leading to reduced growth, lifespan, and reproduction.

Additionally, microplastics can act as a vector for various toxic contaminants and hydrophobic pollutants from the surrounding environment, further exacerbating their impact on marine life. When bacteria encounter microplastics, they tend to produce more organic matter and consume more oxygen. This process can slow down the flux of oxygen and CO2 between the ocean and the atmosphere.

The impact of microplastics on the biological carbon pump is a growing concern among scientists and conservationists. While the exact mechanisms are still being studied, there is a potential for microplastics to disrupt this pump and slow down the ocean's ability to absorb CO2. With the increasing levels of plastic pollution in the ocean, it is crucial to address this issue to mitigate its potential impact on climate change.

Marine ecosystems are impacted by contaminants, making wildlife less resilient to climate change

Marine ecosystems are bearing the brunt of human-made global warming. As the planet's greatest carbon sink, the ocean absorbs excess heat and energy from rising greenhouse gas emissions. Marine ecosystems are being impacted by contaminants, making wildlife less resilient to the effects of climate change.

The ocean absorbs around 90% of the heat generated by rising emissions. This warming of the ocean leads to cascading effects, including ice-melting, sea-level rise, marine heatwaves, and ocean acidification. These changes have a lasting impact on marine biodiversity and the lives of coastal communities.

Contaminants in the ocean, such as plastic and industrial chemicals, are making it harder for wildlife to adapt to these changes. Plastic floating in the ocean has a devastating and well-documented effect on marine wildlife. Fish, seabirds, sea turtles, and mammals become entangled in or ingest plastic debris, causing suffocation, starvation, and drowning.

Microplastics, tiny plastic particles smaller than 0.2 inches in diameter, are also ingested by marine organisms. Research suggests that microplastics affect the ability of marine microorganisms to absorb carbon dioxide and release oxygen. Plankton, for example, sequesters 30-50% of carbon dioxide emissions from human activities, but its capacity to do so decreases after ingesting microplastics.

In addition to plastic pollution, industrial chemicals such as polychlorinated biphenyls (PCBs) are also contaminating the ocean. These persistent chemicals can be stored in Arctic ice and permafrost and released back into the environment as the climate warms. This poses an increased threat to marine wildlife and human health, as PCBs have been linked to reproductive, cardiovascular, kidney, and nervous system problems.

The combined effects of contaminants and climate change create a vicious cycle where marine wildlife becomes less resilient. As the ocean warms, contaminants are released from melting ice, further polluting the water and harming wildlife. At the same time, climate change-induced events such as flooding and storms will increase the amount of plastic and chemical pollution in the sea.

Addressing marine pollution and mitigating climate change are crucial for protecting marine ecosystems and wildlife. Moving towards a circular economy, reducing plastic production and use, and preventing harmful chemicals from entering the ocean are essential steps to break this cycle and build resilience in marine wildlife.

Ocean warming leads to coral bleaching and reef degradation

Ocean warming is one of the most significant threats to coral reefs, and it is a problem that is getting worse. The oceans absorb around 90% of the excess heat from rising emissions, and this is causing ocean temperatures to rise. This warming has a number of effects, including ice-melting, sea-level rise, and marine heatwaves. It is the heatwaves that are causing coral bleaching and reef degradation.

Coral reefs are complex ecosystems that support a huge variety of marine life. They are bright and colourful due to the presence of microscopic algae called zooxanthellae, which live within the coral in a mutually beneficial relationship. However, when ocean temperatures rise, the coral becomes stressed and expels the algae. As the algae leave, the coral fades and appears bleached. If the temperature remains high, the coral will not allow the algae to return and will eventually die.

Bleaching is not an isolated issue. Between 2014 and 2017, around 75% of tropical coral reefs experienced heat stress severe enough to trigger bleaching, and 30% of reefs were affected badly enough for the heat stress to kill the coral. The Great Barrier Reef, one of the most complex natural ecosystems on the planet, has experienced four mass coral bleaching events in just seven years, reducing shallow water coral reefs by 50%.

Coral reefs can sometimes recover from bleaching, but only if temperatures drop and ocean conditions return to normal. As ocean temperatures continue to rise, this is becoming less likely. Warmer oceans also cause coral disease, which can spread quickly through a stressed reef. The combination of bleaching and disease means that reefs are unable to recover, and the entire ecosystem begins to deteriorate.

To protect coral reefs, urgent action is needed to address the root cause of the problem: climate change. This means taking immediate steps to reduce emissions and slow the rate of ocean warming. It is also important to strengthen key ecosystems like seagrass meadows, mangroves, and wetlands, which can help absorb carbon dioxide and combat climate change. By working together, we can give coral reefs a chance to adapt and survive in a changing ocean.

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