Ocean Plastic & Climate Change

When we think of plastic pollution in the ocean, we usually imagine how it affects wildlife. But as it turns out, ocean plastics actually have a significant effect on climate change. In this article, we’re going to break down the three factors that tie ocean plastic to climate change: 

  • Plastic manufacturing
  • Plastic decomposition in the ocean
  • Microplankton consuming plastic particulates

Plastic Manufacturing

The manufacturing of plastic products is heavily dependent on the fossil fuel industry. The polymers in plastic are actually made from heavily refined petroleum and natural gas. The extraction of natural gas and petroleum is extremely energy-intensive and releases tons of greenhouse gasses. This is one of the main drivers of climate change.

The next phase is the refining of these fossil fuels into plastic polymers, also an energy-intensive process. Experts say that between 4% and 8% of annual global oil consumption is tied to plastics. In 2015, it was found that just 24 ethylene plants in the US produced as much CO2 as 3.8 million passenger vehicles. 

While several movements aim to curb the use of single-use plastic, growing populations are demanding more of it. Experts say that by 2050, plastics may account for up to 20% of global oil consumption.

Plastic Decomposition

New research is shedding light on how ocean-based plastics continue to release greenhouse gasses as they decompose. Scientists have found that a common type of plastic called low-density polyethylene (LDPE) releases greenhouse gasses like methane and ethylene when exposed to the sun. Everyday products made of LDPE include plastic rings on soda cans, Saran wrap, and grocery bags. 

While the study focused on the plastic on the ocean’s surface, there’s still research to be done on whether or not plastics deeper below the waves release greenhouse gasses. The same study found that plastics strewn along the coastlines released greenhouse gasses at a higher rate. 

Many plastics are lost in the depths of the sea and will remain there indefinitely. With a steady supply of plastic pollution entering the world ocean, greenhouse gas emissions from decomposing ocean-based plastic will become a growing concern.

Microplankton & Microplastics

Microplankton do a ton of work when it comes to helping sequester carbon from the atmosphere. When these tiny creatures photosynthesize, they absorb carbon dioxide and convert the carbon into sugars. These microplankton are then consumed by larger wildlife, thus feeding the oceans. 

Although microplankton are small, they make up a considerable portion of the ocean’s biomass. Combined, they act as a sort of “biological pump” that pumps CO2 from the atmosphere into the sea. When these microplankton absorb plastic particles, it inhibits their ability to photosynthesize and thus dampens the effect of the biological pump. 

As more plastic enters the oceans, the microplankton are less able to absorb carbon dioxide. This leads to a runaway effect where more carbon enters the atmosphere while the plankton absorb less, leaving more overall CO2 in the atmosphere.

Key Takeaways

Many of us associate ocean plastic pollution with harm to wildlife, but plastic pollution also accelerates climate change. 

Plastics are energy-intensive to manufacture and require the use of fossil fuels which releases greenhouse gasses. If that wasn’t enough, many types of plastics emit carbon during decomposition. 

The tons of plastic waste floating in the ocean is releasing gasses like methane and ethylene as they break down. These plastics then decompose and become microplastics, where small organisms mistake them for food. 

Microplankton that absorb plastic particulates have an inhibited ability to photosynthesize and absorb CO2. This slows down a massive ocean-based carbon sequestration system, where billions of tons of microplankton absorb atmospheric CO2 into the sea. Researchers are now beginning to uncover the full effects of ocean plastic pollution, and some believe that we’re just scratching the surface.

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