Microplastics are undermining the ocean’s power to absorb carbon

Microplastics are tiny plastic particles measuring less than five millimeters. Over time, they have spread across nearly every part of the planet. Researchers have detected them in deep ocean waters, lakes and rivers, the air, soil, Arctic ice, and even inside the human body. Their widespread presence poses growing environmental risks. These particles can carry toxic substances that are consumed by wildlife and people, contributing to disease, ecosystem disruption, harm to marine organisms, and declining soil quality.

Despite the urgency of climate change, scientists say the connection between microplastics and climate systems has received far less attention than it deserves, especially in marine environments. As researchers explain in a study published in the Journal of Hazardous Materials: Plastics, “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.”

How Microplastics Disrupt Ocean Carbon Cycling

In ocean ecosystems, microplastics interfere with natural carbon storage by affecting phytoplankton and zooplankton, organisms that are essential to carbon cycling. The study also highlights the role of the plastisphere, a community of microbes that forms on the surface of microplastics. According to the researchers, this microbial layer contributes to GHG (greenhouse gas production) through its complex biological activity.

Microplastics are already recognized as harmful pollutants, but the study points to an additional and less visible danger. “Our study shows they also interfere with the ocean’s ability to absorb carbon dioxide, a process critical for regulating Earth’s temperature,” said Dr. Ihsanullah Obaidullah, Associate Professor of Integrated Water Processing Technologies at the University of Sharjah and the study’s corresponding author.

Dr. Obaidullah added, “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.”

A Hidden Climate Threat in Plain Sight

Dr. Obaidullah described the research as a “collaborative perspective” involving scientists from China, Hong Kong, Pakistan, and the United Arab Emirates. “We have highlighted an overlooked link between microplastics and climate change. We call for urgent global action to address this emerging threat.”

Published under the title “Microplastics and Global Warming: A Hidden Climate Threat Uncovered in a New Perspective,” the study provides a scoping review of existing research. By examining where evidence already exists and where gaps remain, the authors identify a largely unrecognized greenhouse effect linked to microplastics.

“Oceans are Earth’s largest carbon sink,” Dr. Ihsanullah explained. “Microplastics are undermining this natural shield against climate change. Tackling plastic pollution is now part of the fight against global warming.”

The researchers emphasize that “biological carbon pumping” — the ocean’s natural process that transfers carbon from the atmosphere into the deep sea layers — is the main mechanism connecting microplastics to climate change. “MPs interfere with this process by reducing phytoplankton photosynthesis and impairing zooplankton metabolism,” the authors write.

Another important factor is the plastisphere. This microbial layer forms biofilms on plastic surfaces in aquatic environments and includes organisms involved in nitrogen and carbon cycles. The researchers warn that microplastics also release greenhouse gases as they degrade, further amplifying their impact on the climate system.

How the Research Was Conducted

Instead of following a traditional systematic review process, the researchers used an integrative narrative approach to examine previous studies. Their work relied on desktop research and drew from peer reviewed articles, international organization reports, and other authoritative sources focused on microplastics, ocean health, climate change, and related social and environmental issues.

Dr. Ihsanullah noted that, unlike protocols such as PRISMA, the study did not apply strict inclusion or exclusion criteria. The goal was to connect concepts and themes across disciplines. In total, the team reviewed 89 studies published mainly after 2015, covering research from 2010 to 2025. This broader approach allowed the authors to assess emerging evidence, identify knowledge gaps, and discuss policy implications related to climate change, the Sustainable Development Goals (SDGs), and human rights.

The authors point out that much of the existing research has focused on detecting microplastics and developing cleanup methods. As they write, “The extent to which microplastics affect climate change, ocean health, and associated systems is currently unknown. This can be mostly because the issue is novel, intricate, and multifaceted. The significant ecological effects of plastic pollution in the oceans are well recognized, but its exact connections to these extensive environmental processes are not well understood.”

To close these gaps, the researchers call for future studies that examine how microplastics interact with climate dynamics. They argue that better understanding these links could lead to a shift in “perspective in research and policymaking.”

By addressing both ecological and economic impacts, the study aims to support more effective strategies for reducing plastic pollution and limiting its role in worsening problems such as oxygen depletion and ecosystem instability.

Why Plastic Pollution Is So Widespread

Plastics are deeply embedded in modern life because they are durable, affordable, and versatile. They are used in food packaging, medicine, construction materials, insulation, electronics, aircraft components, consumer products, and healthcare applications.

This widespread use has led to enormous production levels. A 2025 U.N. report estimates that more than 400 million tonnes of plastic are produced each year. About half of this material is designed for single use, and less than 10 percent is recycled. Without intervention, annual plastic production could triple by 2060.

So far, humans have produced more than 8.3 billion tonnes of plastic. Around 80 percent of it has ended up in landfills or the environment, while only nine percent has been recycled.

Although plastics offer clear benefits, the authors warn that “their environmental footprint across the entire life cycle has become a growing concern. These plastics, being highly persistent, have become a pressing global environmental challenge.”

They also note that “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.”

Calls for Coordinated Global Action

The researchers caution policymakers against overlooking the long term effects of microplastics, even if current impacts seem limited. They write that “while their (microplastics) current impacts may seem minor, their growing accumulation suggests future significance. The impact of MPs on ocean health, particularly concerning potential ocean warming and acidification, remains an area of concern.”

The authors stress that plastic pollution and climate change must be addressed together. “In this way, the effects of climate change could be lessened by taking appropriate action to slow down the production of microplastics,” they state.

Among their recommendations, the researchers urge the United Nations to reconsider how plastics are addressed within the Sustainable Development Goals. They point out that “plastics are currently represented by a single indicator, which may not adequately capture the widespread risks posed by microplastics across diverse ecological systems.”

They also call for coordinated governance frameworks that address both microplastic pollution and climate change, particularly in relation to ocean warming and acidification.

To protect the oceans and maintain their ability to absorb carbon dioxide, the authors highlight several priorities. These include cutting back on single use plastics, improving waste management systems, encouraging biodegradable alternatives, and expanding research into how microplastics affect ocean temperatures and carbon cycles. They also recommend using AI driven monitoring tools and new materials to reduce plastic waste.

Looking ahead, 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.”