Can We Bet the Planet on Technologies That Don't Yet Exist?
The clock is ticking, and we're placing a high-stakes wager on our future.
Imagine a world where we can literally pull the pollution driving climate change right out of the air. This is the promise of Negative Emissions Technologies (NETs)—a suite of daring strategies ranging from massive machines that filter carbon dioxide from the atmosphere to enhancing natural processes to store more carbon in trees, soil, and the ocean.
As global temperatures continue to rise and emissions remain stubbornly high, the world is increasingly betting on these technologies to clean up the mess. The concept is simple in theory: remove more greenhouse gases from the atmosphere than we emit, ultimately cooling the planet. The reality, however, is far more complex. This article explores the high-stakes gamble we are taking by relying on these still-developing technologies to rescue us from climate catastrophe.
2024 became the first year where average global warming exceeded the 1.5°C threshold for several consecutive months 7 .
At current emission rates, our remaining carbon budget will be exhausted within a decade 2 .
The science is unequivocal. The Intergovernmental Panel on Climate Change (IPCC) has consistently shown that meeting the Paris Agreement's goal of limiting global warming to 1.5°C above pre-industrial levels is now virtually impossible through emission reductions alone 2 . We have already entered a period of "climate overshoot," with 2024 officially becoming the first year where average global warming exceeded the 1.5°C threshold for several consecutive months 7 .
The remaining global carbon budget—the amount of CO₂ we can still emit—is vanishingly small. At current emission rates, it will be exhausted within a decade 2 . Furthermore, certain sectors like aviation, shipping, and heavy industry are incredibly difficult to decarbonize completely. Negative Emissions Technologies are now seen as essential for two critical tasks:
Without NETs, the goal of achieving "net-zero" emissions—a balance between emissions produced and emissions removed—becomes unattainable. The question is no longer if we need them, but which ones we should deploy, and at what risk.
Already breached in 2024
NETs encompass a wide spectrum of approaches, broadly categorized into nature-based and technology-based solutions. Each comes with its own potential, challenges, and stage of development.
Leveraging the natural power of ecosystems to sequester carbon.
Human-made systems to capture and store carbon.
Combining natural and engineered solutions.
| Technology/Practice | Type | Technological Readiness | Key Challenges & Considerations |
|---|---|---|---|
| Afforestation/Reforestation | Nature-based |
|
Land-use competition, long-term storage security, fire risk |
| Soil Carbon Sequestration | Nature-based |
|
Measurement verification, saturation over time |
| Biochar | Hybrid |
|
Feedstock availability, market development |
| BECCS | Engineered |
|
Large land, water, and nutrient requirements |
| DACCS | Engineered |
|
Very high energy demands and cost |
| Enhanced Weathering | Engineered |
|
Massive mining operations, slow verification |
While many NETs are conceptual, a groundbreaking experiment at Northwestern University offers a tangible glimpse into an innovative carbon-negative future. Researchers have developed a process to create a carbon-negative building material using three abundant resources: seawater, electricity, and carbon dioxide 9 .
The researchers started by inserting electrodes into seawater and applying a low electrical current. This splits water molecules, producing hydrogen gas (a clean fuel) and hydroxide ions 9 .
While the current is still on, they bubbled CO₂ gas through the electrified seawater. This changes the water's chemistry, increasing the concentration of bicarbonate ions 9 .
The hydroxide and bicarbonate ions then react with dissolved calcium and magnesium ions naturally present in the seawater. This reaction produces solid minerals, primarily calcium carbonate and magnesium hydroxide, which are the same minerals found in natural sand and shells 9 .
By carefully controlling factors like voltage, current, and CO₂ injection rate, the team could dictate the properties of the resulting material—making it flaky and porous or dense and hard, suitable for different applications 9 .
Seawater Input
Electric Current
CO₂ Injection
Mineral Output
Hydrogen Byproduct
The significance of this experiment is multi-layered. The process successfully converts gaseous CO₂ into a stable, solid form, permanently locking it away. Depending on the mineral composition, the resulting material can store over half its weight in CO₂. For example, one metric ton of material could sequester over half a metric ton of CO₂ 9 .
This "sand" can be used as a substitute for natural sand or gravel in concrete, cement, plaster, and paint. This could help decarbonize the construction industry, which is responsible for 8% of global CO₂ emissions. Professor Alessandro Rotta Loria envisions a "circularity" where cement plants capture their own CO₂ emissions and use nearby seawater to transform them into construction materials, creating permanent carbon sinks in our cities 9 .
| Aspect | Result | Implication |
|---|---|---|
| Primary Inputs | Seawater, Electricity, CO₂ | Uses abundant resources; avoids freshwater use. |
| Key Outputs | Calcium Carbonate, Magnesium Hydroxide, Hydrogen Gas | Creates valuable material and a clean fuel. |
| CO₂ Storage Capacity | >50% of material weight by mass | Highly efficient at sequestering carbon. |
| Potential Applications | Concrete, Cement, Plaster, Paint | Integrates into a high-emission industry. |
| System Vision | Modular reactors at industrial sites | Enables circular economy, avoids ocean ecosystem disruption. |
Placing our hopes in NETs is not without profound risks. Critics and researchers warn that this gamble could backfire spectacularly.
The very existence of NETs could be used as an excuse to delay the deep and urgent emission cuts we need today. This phenomenon, known as "mitigation deterrence," is a significant danger. If policymakers and industries assume we can just clean up the mess later, they may avoid the difficult but essential transition away from fossil fuels now 2 7 .
Some geoengineering approaches, particularly Solar Radiation Management (SRM) which aims to cool the planet by reflecting sunlight, carry existential risks. A concept known as "termination shock" describes what would happen if SRM were deployed but then suddenly stopped: global temperatures would skyrocket rapidly with devastating consequences 7 .
Large-scale deployment of NETs like BECCS would require enormous amounts of land, water, and energy, potentially competing with food production and biodiversity conservation 2 . As one analysis notes, "What lies behind the potential deployment of geoengineering is a series of risks across several domains," including ecological and international security 7 .
There is currently no robust international framework to govern the testing, deployment, and monitoring of these powerful planetary-scale technologies. This raises thorny questions: Who gets to decide? Who is liable if something goes wrong? 7
"What lies behind the potential deployment of geoengineering is a series of risks across several domains," including ecological and international security 7 .
So, where does this leave us? The consensus from leading research projects, such as the EU-funded NEGEM study, is clear: we cannot rely on a single silver bullet. The most prudent path is to develop a diverse portfolio of NETs .
"No single NETP can achieve the required CDR on its own," the study concludes, noting that all methods involve trade-offs. A portfolio approach balances these trade-offs, using nature-based solutions for their co-benefits (like biodiversity and ecosystem restoration) and engineered solutions for permanent carbon storage .
The Stanford study on California's net-zero goal echoes this, breaking down the path as needing a mix of commercial technologies (52%), early-stage technologies (25%), and research-phase breakthroughs (23%) 1 .
This remains the most critical and non-negotiable action. NETs are a supplement, not a substitute.
We must fund research to improve efficiency, reduce costs, and understand the full impacts of these technologies.
We need clear rules and oversight for testing and deploying NETs to ensure they are used safely, ethically, and equitably.
The negative emissions gamble is one we are forced to take. The stakes—the future of our planetary systems—could not be higher. By understanding the tools, the risks, and the immense challenge ahead, we can make more informed bets. The goal is not to find a perfect solution, but to avoid a catastrophic loss. The time to place our bets wisely is now.