Sounding the alarm: Microplastics are disrupting photosynthesis around the world

Tiny microplastic fragments, often smaller than a grain of rice, are turning up in surprising places. From city streets to remote oceans, they persist in the air, water, and soil.

Scientists have learned that these particles can also invade the human body, showing up in organs that keep us alive.

For years, researchers have warned us about the possible dangers microplastics pose to animals, our food sources, and human health. Now a fresh study suggests even plants are feeling the pressure.

Plants, photosynthesis, and microplastics

This new research from 5 Gyres Institute offers new clues about how these plastic particles affect photosynthesis.

The team gathered over 3,200 records from across the globe, focusing on how tiny bits of microplastics alter photosynthesis by changing the way plants use sunlight to produce energy.

Their analysis spans common food crops and aquatic species, highlighting concerns about weakened growth.

For communities that rely on healthy harvests and marine resources, these findings add a fresh dimension to the worldwide plastic conversation.

“It’s really scary,” says Marcus Eriksen, a marine scientist at the 5 Gyres Institute, a nonprofit plastic pollution research organization, who was not involved in the study.

How microplastics spread far and wide

Most microplastics come from everyday sources. Plastic bottles, packaging, and synthetic clothing shed fibers that break into smaller pieces. Rain and wind carry these particles into rivers, and eventually they end up in oceans.

In agricultural fields, plastic mulch or irrigation systems contribute fragments that seep into the soil. Over time, these bits degrade further, leading to a steady accumulation in places we least expect.

This constant spread worries experts because smaller sizes mean they can slip into living organisms more easily.

Researchers have found these particles in fish, shellfish, and even table salt. In recent years, labs have also identified plastic remnants in bottled water and tap supplies.

While ongoing investigations continue to measure how widespread they are, one thing is clear: once plastic breaks down, it does not disappear. That lingering presence has potential consequences for all life on Earth.

Microplastics impede photosynthesis

In this new analysis, researchers show that microplastics reduce photosynthesis by 7 to 12% across different plant species.

A computer model backs this up, indicating that plastic particles can lower chlorophyll levels by 11 to 13%.

Chlorophyll is the green pigment that helps plants capture sunlight for food production, so any dip in its presence can affect overall growth.

Every year, this pollution could cause a loss of 109 to 361 million metric tons of crops and 1 to 24 million metric tons of seafood, according to the study.

Because of microplastic buildup, global harvests may drop by 4 to 13% yearly, and food from the ocean could decline by up to 7%.

Even minor disruptions to plant growth may have ripple effects on human nutrition and economies that rely on farming.

Challenges for the food supply

Beyond plants, these particles also affect marine life, which many communities rely on for protein. Scientists report that if microplastic pollution continues unchecked, seafood yields could suffer even further.

They are associated with an increase in people’s risk of heart attack and stroke, and they have been found to hamper growth and reproduction in multiple species.

Worries about food safety and supply also arise when these pollutants accumulate in organisms that people eat.

Researchers suggest that a modest 13% reduction in these particles could prevent the loss of up to 47 million metric tons of crops and 3 million metric tons of seafood each year, translating to a 30% cut in overall harm.

This projection highlights the importance of tightening plastic regulations and improving waste management to protect food resources.

Why does any of this matter?

Reduced photosynthesis does not only disrupt food webs. When plants capture less carbon dioxide, there is less natural removal of this greenhouse gas from the atmosphere.

In many climate strategies, forests and marine algae are expected to absorb significant amounts of carbon in the coming decades. If plastic particles undermine that process, climate models may need to be revised.

Most projections assume stable plant performance over time. Any drop in growth or carbon uptake could make global warming harder to control.

With ecosystems already under stress, additional strain from microscopic plastic fragments raises concerns about future carbon storage in forests, grasslands, and kelp beds.

Sounding the alarm

The study’s authors emphasize the need for international efforts to address plastic waste, pointing out that large pieces eventually degrade into smaller and more invasive forms.

A global treaty on plastic issues has been in discussion since 2017, yet recent negotiations concluded without a formal agreement.

Marine biologist Richard Thompson, who specializes in microplastic pollution at the University of Plymouth in England and was not involved in the study, notes that delaying action only increases the risks.

“If we don’t take action now,” he adds, “within the next 70 to 100 years, we’ll see much wide-scale ecological harm.”

Researchers say that lowering even a small amount of microplastic pollution could help protect crops, preserve marine life, and support our climate goals.

Taking action now can guard our health and ensure a healthier environment for generations to come, which doesn’t seem like too much to ask of humanity.

The full study was published in the journal Proceedings of the National Academy of Sciences.

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