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Facing Climate Crisis: The Urgency of Achieving Negative Carbon Emissions

Maggie Johnson

By Maggie Johnson

December 6, 2024

Image Credit: “Concept of Net Zero Emissions. 27577428 Vector Art At Vecteezy,” available at Yahoo Images (12/06/2024).


The impact of human-caused climate change is not a distant concern; it's an urgent issue that demands our immediate attention. With its disastrous consequences becoming more frequent and severe, the signs of global warming are evident from the devastating wildfires in Australia and the floods in England to the rapidly shrinking ice in the Arctic. This week alone, climate change has wreaked havoc in various parts of the world, leaving us to ponder: How bad will things get in the future? And what can we do to prevent it?

To halt global warming, the key strategy is to cut carbon emissions to zero. The United Kingdom, Denmark, and Norway aim to achieve net zero emissions by 2050, with Sweden aiming for 2045. However, the most significant contributors to emissions, including China, the United States, and India, need to be faster to take substantial action. Political will is essential in this regard. As a result, experts believe that to limit global warming to no more than two °C above pre-industrial levels by 2100, we will need to go beyond simply halting emissions. Quite simply, the way to achieve negative carbon emissions is removing more carbon dioxide (CO2) from the atmosphere than we release.

This is a daunting challenge. Some may view it as an impossible goal. Still, it is crucial to understand why this is not just a theoretical question—many of the most optimistic climate scenarios already assume we will need to achieve large-scale harmful emissions. Some climate scientists, like Kevin Anderson and Glen Peters, have warned that we cannot rely too heavily on these strategies without understanding the complexities involved. They argue that we might inadvertently create a dangerous false sense of security, which could leave vulnerable communities, particularly those in poverty, paying the highest price. This could lead to a delay in implementing more effective solutions, exacerbating the impacts of climate change.

In 2018, global CO2 emissions from human activity amounted to around 37 billion tonnes. To keep global warming under control, the National Academy of Sciences estimates that we will need to remove about 10 billion tonnes of CO2 annually by 2050, with that number doubling by 2100. The question is: How can we achieve this?

One of the most publicized efforts to tackle carbon removal is through direct air capture technology, such as machines developed by companies like Climeworks. These machines capture CO2 directly from the atmosphere using a chemical process. While this technology holds promise, it is currently prohibitively expensive—around $500 per tonne of CO2 removed. Even if costs come down, the current capacity of such machines is nowhere near sufficient to meet the necessary scale of carbon removal. The global demand for beverage-grade CO2, a relatively small market, is just 6 million tonnes per year—far below the scale needed to address global emissions.

Another proposed carbon removal method is using CO2 to produce plastics. Companies like RenewCO2 are exploring this idea, but even if the technology becomes viable, we would need to dramatically increase plastic production—potentially by tenfold—to remove 10 billion tonnes of CO2 annually. This would also require ensuring that the production process itself does not rely on fossil fuels, which would offset the benefits. These examples highlight an important truth: many of the technologies we are considering now may only become viable much later in the century, if at all.

A more promising avenue for carbon removal is in agriculture. In 2004, the world produced roughly 5 billion tonnes of crop residue, including plant stems and leaves. Capturing and sequestering this carbon-rich waste could make a substantial difference. One exciting proposal comes from environmental engineer Stuart Strand and physicist Gregory Benford, who have explored the possibility of dumping crop residue into the ocean. While this idea is still under investigation, it holds promise in keeping carbon sequestered for hundreds of years before it returns to the atmosphere.

Beyond this, there are numerous ways to improve agricultural practices to enhance carbon sequestration in soil. For example, reducing tilling allows organic matter to decay more slowly, and using biochar—partially burned plant material—as fertilizer can help lock carbon into the soil. The National Academy of Sciences estimates that improvements in agriculture could remove up to 3 billion tonnes of CO2 annually, a significant contribution to the overall goal.

Forests are also essential for capturing and storing carbon. While mature forests can eventually reach a steady state where the amount of carbon they remove is balanced by the carbon they release through decay, young forests have a greater capacity to absorb carbon as they grow. A 2019 paper in Science argued that the Earth has room for about 4 million square miles of new forests, which could absorb up to 730 billion tonnes of CO2 as these trees mature. However, planting forests on such a vast scale would only offset about 20 years of current global emissions, and some experts have criticized the study for overly optimistic assumptions. Nonetheless, better forest management and reforestation could still contribute significantly to carbon removal, with the National Academy of Sciences suggesting that it could remove 2.5 billion tonnes per year in the short term.

Another option for carbon removal is the production of biofuels. When we burn biofuels—fuels derived from plants—we are releasing carbon recently captured from the atmosphere. This creates a net-zero carbon cycle, an improvement over burning fossil fuels. However, carbon capture is the key to making biofuels a significant part of the solution. If we could capture the CO2 released when burning biofuels and store it underground, this method could remove up to 5.2 billion tonnes of CO2 annually.

Despite the potential of these methods, it is essential to acknowledge the challenges they present. Implementing them at the required scale would be a monumental task, and the logistics of storing carbon underground, for example, present risks and uncertainties. However, the success of these strategies could lead to a significant reduction in global emissions, offering hope for a more sustainable future.

The industries that produce the most material on the planet—such as cement production—also offer opportunities for carbon removal. Cement production accounts for about 7% of global CO2 emissions, and some scientists have developed new types of cement that can absorb carbon as they dry. While this technology is still in its infancy, its potential to help address emissions in the construction industry is significant.

New technologies may hold the key to achieving negative carbon emissions as we look ahead. However, these technologies will take time to develop and scale. In the meantime, we must push forward with the solutions we have, such as improving agriculture, reforesting large areas, and capturing and storing carbon from biofuels. The question is whether we can achieve these goals and if we are willing to take the necessary steps now. The path to net zero emissions is fraught with challenges, but it is possible with the proper political and economic will. The decisions we make today will shape the future of our planet, and we cannot afford to delay.


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