Plastic pollution putting killer whales and sharks most at risk

By Stephen Beech

Plastic pollution is worse because of global warming, with killer whales and sharks most vulnerable, new research warns.

Increased toxicity from waste plastic in a warmer climate is highly likely to be affecting whole ecosystems, with potentially "disproportionate" impacts on apex predators such as orcas and sharks, say scientists.

A four-meter basking shark washed up dead on a beach at Portgordon, near Buckie in Scotland, last month, was found to have plastic in its stomach.

The new report, by scientists from Imperial College London, is calling for "urgent" action to avoid irreversible ecological damage by stemming the tide of microplastics entering the environment.

The Imperial team says climate change conditions turn plastics into more mobile, persistent, and hazardous pollutants.

That is done by speeding up plastic breakdown into microplastics - microscopic fragments of plastic - spreading them vast distances, and increasing exposure and impact within the environment.

And the team warns that the impact is set to rise as both plastic manufacturing and climate effects increase.

Global annual plastic production rose 200-fold between 1950 and 2023.

The report, published in the journal Frontiers in Science, urges eliminating non-essential single-use plastics - which account for 35% of production, limiting virgin plastic production, and creating international standards for making plastics reusable and recyclable.

Lead author Dr. Frank Kelly said: “Plastic pollution and the climate are co-crises that intensify each other.

"They also have origins - and solutions - in common.

“We urgently need a coordinated international approach to stop end-of-life plastics from building up in the environment.”

The research team conducted a comprehensive review of existing evidence that highlights how the climate crisis worsens the impact of plastic pollution.  

They say rising temperatures, humidity, and UV exposure all boost the breakdown of plastics.

Extreme storms, floods, and winds can increase fragmentation as well as dispersal of plastic waste – with six billion tons and rising – into landfill, aquatic and terrestrial ecosystems, atmospheric environments, and food webs.

There are growing concerns about the persistence, spread, and accumulation of microplastics that can disturb nutrient cycles in aquatic ecosystems, reduce soil health, and crop yields.

They also adversely affect feeding, reproduction, and the behavior of organisms that are capable of ingesting them, should levels exceed safe thresholds.

The researchers say microplastics can also act as "Trojan horses" to transfer other contaminants such as metals and pesticides.

Study co-author Dr. Stephanie Wright said: “There’s a chance that microplastics – already in every corner of the planet – will have a greater impact on certain species over time.

"Both the climate crisis and plastic pollution, which come from society’s over-reliance on fossil fuels, could combine to worsen an already stressed environment in the near future.”

She said research into corals, sea snails, sea urchins, mussels and fish shows that microplastics can make them less able to cope with the rising temperatures and ocean acidification.

Filter-feeding mussels can concentrate microplastics extracted from the water, transferring the pollution to predators - increasing levels of microplastics higher in the food chain.

Apex predators may be "particularly susceptible" to the double hit of microplastics and climate change, according to the report.

The researchers says they are likely to experience significant microplastic exposure over the course of their lifetime.

And the potential loss of keystone species that shape the functioning of the wider ecosystem could have "far-reaching" implications, warns the report.

Co-author Dr. Guy Woodward, from Imperial’s Department of Life Sciences, said: "Apex predators such as orcas could be the canaries in the coal mine, as they may be especially vulnerable to the combined impact of climate change and plastic pollution.”

The researchers say we must rethink the whole approach towards using plastics in the first place.

Co-author Dr. Julia Fussell said: “A circular plastics economy is ideal.

"It must go beyond reduce, reuse, and recycle to include redesign, rethink, refuse, eliminate, innovate, and circulate - shifting away from the current linear take–make–waste model.”

Dr. Wright said: “The future will not be free of plastic, but we can try to limit further microplastic pollution.

"We need to act now, as the plastic discarded today threatens future global-scale disruption to ecosystems.”

Dr. Kelly added: “Solutions require systemic change: cutting plastic at source, coordinated global policy such as the UN Global Plastics Treaty, and responsible, evidence-based innovation in materials and waste management."