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Toxic algae remediation: the pathway to gigaton-scale carbon removal

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By Eyal Harel

· 6 min read

Copernicus Sentinel data (2019), processed by ESASource: Copernicus Sentinel data (2019), processed by ESA

The new frontier in carbon capture is booming with brash pioneers, bold ideas, and a burgeoning project pipeline spurred by federal funding, tax incentives, and private sector investment, all coming together to address the greenhouse gas emissions choking our planet. Innovators have stepped forward with new technologies, tools, and practices. Our collective global resolve to save the world from climate change has never been greater.  

Indeed, the urgency of acting on our climate crisis cannot be overstated. The United Nations’ first stocktake report on global commitments to limit temperature rise to 1.5 degrees Celsius shows the world is not on track to meet the targets laid out in the 2015 Paris Agreement

But the simple reality is that we cannot vacuum, scrub, filter, pipe, or bury our way to net zero by 2050. Drastically slashing fossil fuels alone won’t get us there either. 

Rapid decarbonization at scale can only be achieved by investing in marine and freshwater ecosystems and the carbon stored within. By taking advantage of the carbon-soaking superpowers of cyanobacteria, also known as blue-green algae, we can lock away gigatons of CO2 for thousands, if not millions, of years. 

Toxic algal bloom remediation can help resolve the great climate challenge of our time by targeting and sinking toxic blooms with technology that is scalable and immediately deployable. This natural process does not incur the inefficiency, energy load, or high costs of land-based CO2 removal systems. 

That’s not to say that other nature-based climate solutions, along with emissions reduction and land-based carbon capture, are not part of the solution. We need to marshal all of our weapons to slay the climate dragon before us. But to remove carbon dioxide from the atmosphere at an unprecedented rate, in relatively short order, requires leveraging the awesome power of water.

Photo of jellyfish underwater

Earth’s greatest natural carbon sink

Water is the lifeblood of our planet and our greatest natural carbon sink, absorbing approximately 30% of all anthropogenic CO2 emissions. This remarkable feat is orchestrated by the intricate dance of marine organisms and the physical properties of water itself. Phytoplankton, including cyanobacteria, are the microscopic photosynthetic powerhouses of the oceans and contribute significantly to carbon uptake, as they absorb CO2 during photosynthesis and subsequently become part of the ocean's biological carbon pump.

Wetlands also play an indispensable role in sequestering carbon. Rivers, lakes, and estuaries act as conduits, transporting organic matter and terrestrial carbon to the oceans. The intricate web of aquatic life in these bodies of water further enhances carbon cycling.

Carbon-soaking superheroes

Cyanobacteria, ancient, microscopic, single-celled organisms that date back to the very beginnings of Earth, are believed to have been responsible for the oxygenation of the atmosphere and the oceans and are able to grow and survive where other organisms cannot. 

Photo of Cyanobacteria under a microscope

In warmer temperatures, when an abundance of nutrients and pollutants are present, cyanobacteria can explode in numbers and produce powerful toxins. These blooms often appear as blue-green paint splatters or thick mats floating on the water’s surface.  

Cyanotoxins can sicken or even kill humans and animals, threaten drinking water supplies, suffocate aquatic ecosystems, and damage local economies. Harmful blooms close beaches and ruin recreation plans, making swimming, fishing, and boating too dangerous. Just breathing in the vicinity of an algae-choked lake can bring on respiratory problems. Touching the water or even brushing against dried blooms on the shoreline can be fatal to animals.

The toxic menace antagonizing our planet 

Photo of ocean covered with toxic algae bloomsSource: NASA

At least 12 million square miles of ocean are covered with toxic algal blooms. Striking images captured from space show Van Gough-like swirls of bright green amid deep blues; a toxic menace set against the backdrop of Earth’s natural beauty that requires a double take to fully comprehend the magnitude of the problem. Researchers studied those images — 760 thousand captured by NASA between 2003 and 2020 — and concluded ocean coverage of harmful algal blooms increased by over 13% during that period. 

But that’s only a snapshot of the scope of Earth’s harmful algae inundation. Countless acres of wetlands and reservoirs, rivers and streams, lakes and ponds are choked with the toxic slime. By cleaning up these blooms, we can not only reduce a toxic hazard, but can also sequester gigatons of carbon in the process. Here’s how.

Sinking algal biomass

By deploying a floating algaecide, scientists can target the toxic organism on the surface of the water, sparking a biological signal known as programmed cell death. The cells collapse and sink to the sediment carrying with them the carbon they have sequestered. Nontoxic algae are able to move in and once again flourish, helping to renew the health of the ecosystem over time.

Algal bloom remediation not only reduces a toxic hazard, it essentially fixes a ‘broken’ carbon pump by permanently removing vast quantities of carbon, and vacating space and resources for an array of biodiverse, nontoxic species to move in and continue, anew, photosynthetic activity to further the cycle.

Gigaton potential

Scientists have concluded that in addition to significant emissions reductions, we need to remove up to 10 gigatons of carbon each year in order to achieve net zero by 2050. The world is woefully behind in meeting that bar. By treating toxic blooms and sinking carbon-rich algal biomass, we can, for the first time, draw a realistic line toward the goal of removing up to 10 gigatons of carbon per year.

If it were possible to remediate all of the harmful algal blooms worldwide, in one year alone we could remove an estimated 115 gigatons of carbon. That is a mind-blowing number, one that underscores the power of toxic bloom remediation for addressing the world’s carbon problem.


If we are to safeguard our planet and future generations from the perils of a destabilized climate, we must leverage the power of water. Rapid decarbonization at scale can only be achieved by investing in aquatic ecosystems and the carbon stored within. 

The urgency of the moment cannot be overstated. We just experienced the hottest summer on record, with global sea temperatures hitting record highs. Glaciers are melting. Sea levels are rising. Extreme heat, megadroughts, epic floods, and deadly storms are occurring at an accelerating pace. But there is reason for optimism.

The potential for leveraging water to mitigate our climate crisis is powerful - and ready to be tapped. Let’s invest in what will work now before more irreversible damage to our climate is done. Time is running out. To meet aggressive and necessary climate goals we must clean up the toxic algal blooms in our oceans, lakes, and wetlands. We need to forge ahead into this bold new frontier. It is time to cowboy up and get it done. 

illuminem Voices is a democratic space presenting the thoughts and opinions of leading Sustainability & Energy writers, their opinions do not necessarily represent those of illuminem.

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About the author

Eyal Harel is a clean water advocate and CEO of BlueGreen Water Technologies, a global water-tech company whose mission is to restore, safeguard, and optimize the health of water bodies worldwide.

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