Almost all plastic is made from chemicals derived from fossil fuels (mostly oil and gas). The process of extracting and transporting those fuels and then manufacturing plastic creates billions of tonnes of greenhouse gases. Four percent of the world’s annual petroleum production is diverted to making plastic, and another four percent is used in the refining process. The total is projected to become as much as twenty percent by the year 2050. 

How we manage all the plastic that then goes into circulation is equally troubling. Of the almost 380 million tonnes of plastic that the world produces each year, approximately fifty percent is discarded after a single use. Less than ten percent is recycled, which leaves a staggering amount to be disposed of in landfills or by incineration.

Since only a small percentage of plastic was ever recycled, western nations used to rely on countries in Asia such as China, Myanmar and Cambodia to receive our waste plastic. It was more convenient to bale plastic up and ship it to someone else to deal with.

However, poorly-regulated landfills and incineration in those developing nations posed considerable threats to human health and the environment. Globally, in this year alone, researchers estimate that the production and incineration of plastic will release more than 850 million tonnes of greenhouse gases into the atmosphere. By 2050, those emissions could rise to 2.8 billion tonnes.

Alarmingly, at least 8 million tonnes of discarded plastic also enters our oceans each year and plastic pollution at sea is on course to double by 2030. Plastic has even been found in the deepest place on Earth – in the Mariana Trench, nearly 11 kilometres below sea level.

In our oceans, which provide the largest natural carbon sink for greenhouse gases, plastic leaves a deadly legacy. It directly chokes and smothers a host of marine animals and habitats and can take hundreds of years to break down. As the plastic degrades, sunlight and heat cause the plastic to release powerful greenhouse gases, leading to an alarming feedback loop. As our climate changes, the planet gets hotter, more plastic then breaks down, releasing  more methane and ethylene, increasing the rate of climate change, and so perpetuating the cycle.

The smaller particles (known as microplastics) that break off and disperse in the ocean are ingested by marine animals, including plankton, and some of the fish we eat. These tiny plankton play a critical role in removing carbon dioxide from the atmosphere and sequestering it in deep ocean sinks. The full effects of this are still being studied, but the essential premise is that microplastics threaten plankton populations which will result in more carbon re-entering the waters and atmosphere.

Given that our oceans have successfully absorbed thirty to fifty percent of atmospheric carbon produced since the start of the industrial era, it’s easy to see just what’s at stake. And this leads us back to the plastic consumption on land that is driving this mounting plastic pollution crisis. 

The only way we can now address the problem is to curb the production of plastic, especially of the single-use variety, and to ramp up recycling of other plastics.