Plastic pollution is one of several major dangers harming coral reefs worldwide. As some of the most important and diverse ecosystems on the planet, coral health is an indicator of the wider health of our oceans and other marine life. Unfortunately, these undersea sentinels do not bring us good news: Since 1950, more than half of the world’s living coral reefs have died, and along with them, at least 63% of coral reef diversity has also been lost.
Corals may seem like inanimate things, but in fact they are full of life. While only covering 1% of the world’s seafloors, corals create habitat for at least 25% of marine life globally, provide food for coastal and inland communities, support businesses through tourism and recreation, help develop new medicines, build up beaches, and protect shorelines from erosion. They’re estimated to provide the global economy with $29.8 billion per year, which is about the same GDP as a small country.
Corals are in crisis, with reefs bleaching and dying all over the globe. While the biggest threat to their existence is the climate crisis, plastic pollution is among many human-made threats also playing a significant and growing role in diminishing the health of corals all over the world. Despite our need for plastic and fossil fuel production to be cut, production continues to rise—and this threatens the future of corals, our oceans, and ultimately all of us on Earth.
Here’s what you need to know—and how you can help.
Plastic Pollution Harms Corals
Corals are voracious eaters, stunning and catching drifting zooplankton with tiny barbed harpoons built into their bodies. Unfortunately, corals have shown an affinity for eating microplastics, at least in laboratory experiments. Scientists have found that plastic’s chemical signature is attractive to the sensory systems corals use to discern what is food. Zooplankton are tiny, about the same size and shape as many plastic particles, but it seems that corals are selectively attracted to eating plastic (like seabirds and fish) over other types of particulates, such as sand—suggesting a chemical attraction.
Other researchers have linked corals’ ingestion of and other contact with plastic particles to bleaching and other signs of illness, including increased mucus production, tissue loss, algae overgrowth, and death. This harm can occur even if corals spit microplastic out of their bodies following ingestion. Experts believe the plastic could be interfering with corals’ bodily functions, physically, chemically, or both. With the oceans full of microplastics—at least 2 million metric tons on the surface and 14 million metric tons on the seafloor, corals face near-constant exposure.
Larger macroplastics, often intact or partially intact plastic items, also harm corals. Corals that come into contact with plastics have a 20-times increased risk of disease. One major study of coral reefs in the Atlantic, Indian, and Pacific Oceans found that 92% of reefs have visible macroplastic sitting on top of corals. Though plastic pollution is worse on reefs located near more populated cities and markets, even reefs in remote and uninhabited areas are contaminated by plastic.
Climate Change is Killing Corals
The biggest threat to coral reefs is climate change and the warming of oceans around the world. Each year, the ocean absorbs about 30% of human-generated carbon dioxide emissions from the burning of fossil fuels. This warms the oceans and increases ocean acidity (decreasing seawater’s pH), conditions that harm most all species of corals. While corals that grow in warmer environments tend to be more tolerant of higher water temperatures than those in cooler waters, warming is generally a stressor to corals everywhere. Acidic waters weaken corals’ calcium carbonate skeletons, making them more vulnerable to other threats.
And plastics are a significant driver of climate change: 99% of plastics are made of fossil fuels, and plastics emit climate-warming greenhouse gases throughout their endless toxic existence, from the extraction of their fossil fuel ingredients; through plastic production, use, disposal, and pollution. Plastic particles are known to interfere with the ocean’s carbon cycle, contributing further to global warming.
Despite the urgent need to cut our reliance on fossil fuels, the plastics and petrochemical industries plan to triple plastics production by 2060—threatening our chances of keeping global temperature rise below the critical 1.5-degree Celsius threshold. By 2050, plastic production and disposal could generate greenhouse-gas emissions equivalent to 615 coal plants annually and use up to 13% of Earth’s remaining carbon budget. This is a serious problem for all life on Earth, particularly corals. By 2055, scientists estimate that almost all of the world’s coral reefs (99%) will be facing unsuitable living conditions that can cause illness and death.
Take Action
While we can all work to reduce plastic pollution in our own lives, we need systemic change to solve the plastic pollution crisis. This includes global policies to curb plastic production and hold polluters responsible for the mess they’ve created, as well as incentives for governments and businesses to make safe, plastic-free solutions widely available.
