As the climate crisis accelerates, the pressing need to reduce atmospheric carbon dioxide (CO2) levels is undeniable. Yet the path to meaningful progress remains unclear and hotly contested. Industrial carbon capture technologies have received billions in government subsidies, but so far failed to deliver climate-relevant CO2 reductions. Meanwhile, a growing body of research indicates that natural, biological methods of removing and storing carbon could offer a more feasible and holistic solution.

Photosynthesis: Earth's built-in carbon removal

At the heart of biological carbon dioxide removal (CDR) is photosynthesis – the natural process by which plants use sunlight, water and CO2 to produce energy and grow. Through photosynthesis, the world’s vegetation, soil and oceans already absorb massive amounts of carbon.

Research shows that globally, land ecosystems take up nearly 30% of human CO2 emissions through plant growth and soil storage. Oceans additionally absorb around 23% of emissions annually. Together, these natural carbon “sinks” remove over half of the CO2 humans release into the atmosphere every year.

The problem is that natural removal processes cannot keep pace with accelerating human emissions. However, studies indicate the removal potential could be expanded significantly by using land management practices that enhance plant growth, increase soil carbon storage, and restore degraded ecosystems.

Such nature-based solutions represent a promising path for drawing down atmospheric CO2 levels to safer thresholds. Importantly, they would not require costly new technologies, instead leveraging and optimizing Earth's existing carbon absorption systems.

Measuring impact: a biophysical lens

To systematically assess the potential of biological CDR, researchers have employed a “biophysical inputs-outcomes” analysis. This approach objectively compares CDR methods across three vital criteria:

1. Effectiveness – Does the method result in an actual net reduction of atmospheric CO2 levels? 
2. Efficiency – How much land area and energy input is required to remove CO2 at a climate-relevant scale?
3. Co-Impacts – What are the collateral socio-environmental effects, positive or negative?

Using real-world data, these biophysical metrics reveal clear benefits of biological CDR compared to mechanical carbon capture technologies.

Effective natural removal, ineffective industrial capture

On effectiveness, the research finds that industrial methods like direct air capture and carbon capture at power plants or factories have not yet achieved measurable reductions in atmospheric CO2 levels.

Carbon is captured through chemical processes but later released through pipeline leaks, oil extraction, or when used to manufacture fuels and products. The U.S. has provided over $25 billion in government subsidies for mechanical carbon capture, yet there is little evidence it is effectively reducing CO2 levels.

Meanwhile, natural carbon removal processes reliably extract CO2 from the air and store it in vegetation and soil year after year. Studies show that in the U.S., forests, grasslands and agricultural lands already sequester nearly 1 billion tons of CO2 per year through natural plant and soil storage.

With improved land management practices, experts estimate biological removal could readily double in the coming decades. Globally, major opportunities for enhancement exist across biomes, from the extensive forests of the Amazon and Congo Basins to the vast rangelands of Africa, Australia and the Americas. Startups like Africa's Stack Carbon are pioneering natural carbon removal solutions tailored to local contexts to remove and store carbon while empowering communities.

Efficiency: more removal with less resource input

On efficiency, industrial carbon capture requires massive inputs of energy, chemicals, infrastructure and land area to operate at scales relevant to climate impact. Removing just 1 billion tons of CO2 (1 gigaton) would demand a quantity of energy rivaling the entire electricity supply of the United States. 

In contrast, biological systems can remove equivalent amounts of CO2 with negligible energy input simply by utilizing sunlight and natural plant growth processes. Expanding biological storage through reforestation, regenerative agriculture, or ecosystem restoration requires far less land area than deploying mechanical carbon capture and storage at scale.

Nature-based CDR solutions are often readily available and low-cost, whereas industrial methods remain speculative and exorbitantly expensive, with estimates ranging from $500 to over $1,000 per ton of CO2 captured.

Carbon removal that heals the planet 

The collateral impacts of biological CDR are overwhelmingly positive, while those of industrial technologies are predominantly negative. Mechanical carbon capture entails major risks like pipeline leaks, contaminated water supplies and induced seismic events. Chemicals used in the process pose dangers for surrounding communities and ecological systems.

In contrast, improving natural carbon storage through land restoration enhances biodiversity, prevents flooding and fires, improves water and air quality, increases soil fertility and crop yields, and generates new green jobs. Africa's emerging regenerative agriculture sector demonstrates the potential for natural climate solutions to simultaneously sequester carbon while also boosting food security and rural livelihoods.

With care taken to respect indigenous rights and avoid monocultures, research suggests well-planned biological CDR can strengthen ecosystems and human wellbeing overall.

Shifting policy to support natural climate solutions

Findings on the biophysical performance of biological CDR methods point to a need to reform climate policies and public investments. Governments have funneled billions into unproven industrial technologies like direct air capture while providing little support for expanding natural carbon sinks.

Economic policymakers have wrongly approached climate change as a market design issue, rather than a biophysical problem of excessive CO2 in the global commons. Natural systems do not operate for profit. With better science-based policies that invest in what works, biological solutions offer a more efficient and sustainable path to drawing down atmospheric carbon.  

Promising initiatives are emerging worldwide to scale up natural climate solutions, from regional carbon credit schemes to national ecosystem restoration commitments. However, realizing the full potential of biosphere carbon removal will require major public and private investments in regenerative agriculture, forest conservation, and coastal ecosystem protections across the planet.

With climate catastrophe fast approaching, restoring nature may offer our last best chance for a livable future. The research shows it can work. What is needed now is the global political will to prioritize natural systems. With sweeping policy shifts, the biosphere’s immense power of photosynthesis and carbon storage can yet pull humanity back from the brink.