Microplastics are undermining the ocean’s ability to absorb carbon
New research suggests microplastics are disrupting the ocean’s natural ability to absorb carbon dioxide by interfering with marine life and carbon cycles, potentially weakening one of Earth’s most important defences against climate change.
As the microplastic pandemic continues to rage across the globe, recent research has revealed this form of plastic pollution is impairing the oceans’ ability to absorb carbon dioxide, a process that scientists deem to be crucial for regulating Earth’s temperature.
These findings are the latest to join a growing body of research documenting the spread of microplastics across the planet. Defined as plastic particles smaller than five millimetres, microplastics are now found in the deepest ocean basins to Arctic ice, freshwater systems, soils, the air we breathe, and even inside the human body.
Long recognised as environmental pollutants that transport toxins and harm ecosystems, their role in climate regulation has, until recently, received comparatively little scrutiny. But that gap has become the focus of a new perspective published in Journal of Hazardous Materials: Plastics, which argues that microplastics are quietly interfering with oceanic carbon cycling at a time of accelerating climate change.
“Climate disruption and plastic pollution are two major environmental challenges that intersect in complex ways. MPs (microplastics) influence biogeochemical processes, disrupt oceanic carbon pumps, and contribute directly to greenhouse gas (GHG) emissions,” the study’s authors have written.
They point in particular to the biological carbon pump – the natural process by which phytoplankton absorb carbon dioxide through photosynthesis and transport it to deeper ocean layers via marine food webs. According to the study, microplastics disrupt this mechanism by impairing phytoplankton productivity and zooplankton metabolism.
“In marine ecosystems, microplastics alter the natural carbon sequestration by affecting phytoplankton and zooplankton, which are key agents of carbon cycling. Additionally, the plastisphere, a microbial community colonising microplastics, plays a significant role in GHG (greenhouse gas production) due to its diverse microbial networks,” the study has suggested.
An overlooked climate connection
The study’s corresponding author, Dr Ihsanullah Obaidullah, Associate Professor of Integrated Water Processing Technologies at the University of Sharjah, has said the findings reveal a ‘largely hidden dimension’ of plastic pollution.
“While widely recognised as pollutants, our study shows they also interfere with the ocean’s ability to absorb carbon dioxide, a process critical for regulating Earth’s temperature,” he said.
Dr Obaidullah has added that the impacts extend beyond carbon uptake alone, suggesting that microplastics disrupt marine life, weaken the ‘biological carbon pump’, and even release greenhouse gases as they degrade.
“Over time, these changes could lead to ocean warming, acidification, and biodiversity loss, threatening food security and coastal communities worldwide,” he said.
Published under the title Microplastics and Global Warming: A Hidden Climate Threat Uncovered in a New Perspective, the study – brought together through a collaborative effort involving researchers from China, Hong Kong, Pakistan, and the United Arab Emirates – maps existing research rather than presenting new experimental data. By synthesising findings from 89 peer-reviewed studies published largely since 2015, the authors identify gaps in understanding how microplastics interact with ocean health and climate systems.
“Oceans are Earth’s largest carbon sink,” explained Dr Ihsanullah. “Microplastics are undermining this natural shield against climate change. Tackling plastic pollution is now part of the fight against global warming.”
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The role of the plastisphere
Beyond their physical impacts on marine organisms, the authors have highlighted the significance of the plastisphere – a biofilm of microorganisms that colonise plastic surfaces in aquatic environments.
“The plastisphere is home to a variety of microorganisms, the majority of which are involved in biological processes like the nitrogen and carbon cycles,” they note. As plastics degrade, they can also emit greenhouse gases, adding another pathway through which microplastics may exacerbate climate change.
Rather than following a rigid systematic review protocol, the researchers adopted an integrative narrative approach, drawing on peer-reviewed literature, international reports and interdisciplinary sources. This, they argue, allows for a broader conceptual understanding of how microplastics intersect with climate change, the Sustainable Development Goals and human rights.
The study situates these findings within the wider context of global plastic production. According to a 2025 UN report cited by the authors, global plastic production now exceeds 400 million tonnes annually. Around half is designed for single use, and less than 10 per cent is recycled. Without intervention, production could triple by 2060.
To date, more than 8.3 billion tonnes of plastic have been produced worldwide, with roughly 80 per cent ending up in landfills or the environment.
“The increasing demand for and excessive consumption of plastic have led to serious challenges for human and ecosystem health, posing threats to environmental sustainability and food safety,” the authors have warned.
A call for integrated action
Plastic pollution and climate change must therefore be tackled together. Leaders have now been cautioned against underestimating the long-term consequences of microplastic accumulation.
“While their (microplastics) current impacts may seem minor, their growing accumulation suggests future significance,” they write, noting particular concern around ocean warming and acidification.
Among their recommendations are reducing single-use plastics, improving waste management, promoting biodegradable alternatives and investing in research on how microplastics influence ocean temperatures and carbon cycles. They also call on the United Nations to reassess how plastics are represented within the Sustainable Development Goals, arguing that a single indicator fails to capture the scale of the risk.
Dr Ihsanullah said: “Our next step is to quantify the climate impact of microplastics and develop integrated solutions. This is not just an environmental issue; it’s a global sustainability challenge.”
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