A new review published in Frontiers in Science is calling for urgent action to avoid irreversible ecological damage by stemming the tide of microplastics entering the environment.
Climate change conditions turn plastics into more mobile, persistent, and hazardous pollutants. This is done by speeding up plastic breakdown into microplastics - microscopic fragments of plastic - spreading them considerable distances, and increasing exposure and impact within the environment.
This is set to worsen as both plastic manufacturing and climate effects increase. Global annual plastic production rose 200-fold between 1950 and 2023.
The authors, from Imperial College London, urge 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.
"Plastic pollution and the climate are co-crises that intensify each other. They also have origins—and solutions—in common," said lead author Prof Frank Kelly, from Imperial's School of Public Health. "We urgently need a coordinated international approach to stop end-of-life plastics from building up in the environment."
Joint crises
The researchers conducted a comprehensive review of existing evidence that highlights how the climate crisis worsens the impact of plastic pollution.
Rising temperatures, humidity, and UV exposure all boost the breakdown of plastics. Furthermore, 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.
Microplastics can also act as 'Trojan horses' to transfer other contaminants like metals, pesticides, and PFAS 'forever chemicals'. Climatic conditions may also enhance the adherence and transfer of these contaminants, as well as the leaching of hazardous chemicals such as flame retardants or plasticizers.
There is also historical plastic to consider. When ice forms in the sea, it takes up microplastics and concentrates them, removing them from the water. However, as sea ice melts under warming conditions, this process could reverse and become a major additional source of plastic release.
"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," said co-author Dr Stephanie Wright from Imperial's School of Public Health.
Apex predators particularly vulnerable
Combined impacts when both stressors occur together are particularly apparent across many marine organisms. 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 this pollution to predators: effects like this can increase levels of microplastics higher in the food chain.
Species at these higher trophic levels are often already vulnerable to a host of other stressors, whose effects may be amplified by plastics. For instance, a recent study found that microplastic-induced mortality in fish quadrupled with a rise in water temperature. Another study showed that increased ocean hypoxia, which is also driven by warming, caused cod to double their microplastic intake.
Apex predators such as orcas may be particularly susceptible to the double hit of microplastics and climate change. These long-lived mammals are likely to experience significant microplastic exposure over the course of their lifetime.
The potential loss of keystone species that shape the functioning of the wider ecosystem could have far-reaching implications.
"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," said co-author Prof Guy Woodward from Imperial's Department of Life Sciences.
Microplastics are also known to affect ecosystems on land, but these interactions are even more complex and harder to predict than for aquatic life.
Urgent action required on microplastics
The evidence showing increased amounts, spread, and harm of microplastics adds further impetus to calls for urgent action on plastic pollution.
The researchers say we must rethink the whole approach towards using plastics in the first place. "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," said co-author Dr Julia Fussell from Imperial.
This review also demonstrates that integrating interactive effects of plastic pollution and climate stressors offers a way to steer, coordinate and prioritize research and monitoring, along with policy and action.
According to Wright: "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."
"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," said Kelly.
