How will climate change affect microplastics already in the environment?

plastic bag floating in the sea

Understanding why climate change might contribute to increasing plastic pollution is the focus of a new research project starting this month at the University of Portsmouth.

The three-year PhD project seeks to determine whether future environmental conditions – such as higher UV radiation levels, increased temperatures and acidity in the oceans – will cause plastics to shed more microplastics than they do now.

Using projected climate patterns for 50 years’ time from the Intergovernmental Panel on Climate Change, this research is the first of its kind to explore secondary microplastics from older plastics in our future climate scenarios. Until now, studies have concentrated solely on microplastics shedding from brand-new plastics. However, this project will focus on how aged plastics, those that have been in the environment for years, break down under real world conditions.

Professor Fay Couceiro, Professor of Environmental Pollution from the University of Portsmouth, said: “New plastic is strong, but once aged, plastic becomes weaker and breaks up more easily. We expect to see many more microplastics coming off aged plastic rather than new plastic. This is important because it replicates real environmental conditions. Up until now, calculations have been made using new plastic – this method will give us a much more accurate picture of what’s going on. As far as we know this is the first time this has been looked at in conjunction with climate change.”

The project focuses on understanding the secondary pathways through which microplastics enter the environment, such as from storm events, wave action, UV exposure and extreme temperature changes. These environmental stressors, known as weathering and erosion, weaken the structural integrity of plastic over time, causing it to fragment into smaller pieces.

By simulating future climate scenarios, researchers aim to determine how these processes will evolve under increased UV radiation, ocean acidification and more frequent extreme weather events – all of which are expected over the next 50 years.

By using accelerated ageing processes, the researchers will be able to simulate ‘old plastic’. These aged plastics will be tested in two different environments: a UK climate and an Australian one, focusing on five types of common plastics in both current and future climate conditions.

Stephanie Northen, PhD student from the Revolution Plastics Institute at the University of Portsmouth, said: “Our aim is to better understand the fragmentation rates of plastics into microplastic, initially focusing on marine environments. We’ll use a variety of traditional and new bioplastic alternatives and then subject them to different environmental and physical stresses. We can then work out the rate of formation of microplastics and understand more about the impacts of climate change.”

This project is part of a new and innovative cluster of PhD students dedicated to finding solutions to the global plastic crisis. Supported by the UK-based material technologies company Aquapak, this interdisciplinary research program aims to harness individual and collective discoveries to build new knowledge and deliver actionable strategies to solve this growing problem.

Professor Steve Fletcher, Director of the Revolution Plastics Institute, added: “Plastic pollution and climate change are becoming two integral and interlinked focuses of environmental health. Understanding the environmental fate of secondary microplastics from legacy plastic pollution in the marine environment is crucial for evaluating their risk in both current and future climate conditions. Our current understanding of the fragmentation mechanisms and size categories of microplastic particles and other degradation deposits remains limited. Ultimately, we need to reduce the amount of plastic entering our environment.”

The researchers hope their findings will help inform future policy.