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.”
