The ocean generates 50 percent of the oxygen we need, absorbs 25 percent of all carbon dioxide emissions and captures 90 percent of the excess heat generated by these emissions. Our ocean is our planet’s largest carbon sink and it is important to preserve this carbon sink to help regulate our climate.

Well known are the increasing ocean temperatures and acidification of the water due to increased emissions and increased carbon dioxide in the atmosphere. Less known is how plastic in the oceans exacerbates this problem.

Plastic pollution raises beach temperatures by insulating and trapping heat. This not only affects the marine organisms but also threatens the mangroves along the seashores and riverbanks. Mangroves can capture carbon dioxide at rates four times higher than forests can and are an important part of this carbon sink. However, these mangroves are threatened with plastic waste blocking needed light and increasing habitat temperatures.

Plastic pollution also affects the ocean’s plankton. Plankton are small, microscopic organisms which are the basis of the marine food chain, helping feed larger marine organisms which then feed the fish and those higher up in the food chain. Marine phytoplankton produce energy through photosynthesis and are an important carbon sink by converting carbon dioxide to oxygen. Phytoplankton in the oceans accounts for almost half of all photosynthesis on the planet. Marine plants like phytoplankton,seaweed and algae produce 70% of the Earth’s oxygen. Not only are the rising ocean temperatures harming the plankton but so are the rising levels of microplastics. The more plankton ingest these microplastics, the less they can convert carbon dioxide into oxygen and ingesting the microplastics can simply kill the plankton. When these oxygen producing micro-organisms can no longer produce oxygen, then they die, they create dead zones which suffocate sea life.

Another important part of this ocean sink are the coral reefs. The coral reefs are the underwater skeletons of colonies of marine invertebrates called coral. Photosynthetic algae living within the coral tissues convert carbon dioxide to oxygen. Coral reefs, most known to be damaged due to rising ocean temperatures and acidification of the water, are also harmed by plastic pollution. Plastic waste blocks sunlight needed for growth. Larger pieces of plastic as well as microplastics physically abrade and damage the reefs and corals creating wounds and increasing susceptibility to infection. Corals feed on plankton and also ingest the trillions of microplastic particles in the oceans and within the plankton. Ingested microplastics can damage a coral’s gut and reduce the coral’s feeding and growth. Microplastics can also harm the coral with associated toxins in the plastic.

The degrading plastic, on land and in the oceans, releases more greenhouse gases. With more greenhouse gases and rising global temperatures, ocean water temperatures are also rising. Not only will the oceans be less habitable for all its living creatures, the oceans will also be less capable of generating oxygen, less capable of absorbing the carbon dioxide and heat produced by man-made gas emissions.

Continued production of plastic also relies on the use of fossil fuels, adding to the cycle of increased gas emissions. Plastic, in both its production and presence, is a problem for climate change.