Understanding Enhanced Rock Weathering

So, what exactly is enhanced rock weathering? The process begins in the atmosphere.

Carbon dioxide, being soluble, is absorbed by clouds in large quantities. When this gas interacts with water, it forms carbonic acid, which eventually falls as acid rain. Basalt, a common rock type, reacts robustly with carbonic acid, transforming it into soluble carbonate minerals that are then washed into the ocean. This natural weathering process not only sequesters carbon dioxide but also releases essential minerals like phosphorus, magnesium, and calcium into the surrounding soil, acting as a natural fertilizer.

However, this weathering process is typically very slow, explaining why basalt landscapes remain stable even after heavy rainfall. To expedite this process, we can grind basalt into a finer powder to increase its surface area and distribute it over rain-rich agricultural areas. Theoretically, this could significantly enhance carbon sequestration and reduce the need for carbon-heavy fertilizers.

Effectiveness of Enhanced Rock Weathering

Previous studies have confirmed the efficacy of EW in capturing carbon, but they have not extensively examined its impact on crops. Rocks may contain various impurities, including potentially harmful metals, which could counteract the benefits of the fertilizer and affect crop safety.

This leads us to a recent study by David Beerling, a leading figure in EW research. His team conducted field trials from 2016 to 2020 on a maize farm located in the US Corn Belt and has just released their findings. As expected, they discovered that EW effectively sequestered approximately 3 to 4 metric tons of carbon dioxide per hectare annually. More importantly, there was no notable increase in trace metal content in the harvested maize, and nutrient levels in the soil rose, resulting in a yield increase of 12 to 16%!

In essence, their research indicates that EW not only captures substantial amounts of carbon but is also safe for agricultural use, potentially boosting food production significantly.

Contextualizing the Findings

To appreciate the impact of these results, let’s put them into perspective. There are about 1.6 billion hectares of farmland worldwide. If EW were implemented across all these lands, we could capture an estimated 5.6 billion tonnes of carbon dioxide each year, which accounts for roughly 16% of global emissions and 70% of the carbon capture required to reach net-zero by 2050.

Currently, the world produces around 2 billion tonnes of maize annually. Thus, if EW was widely adopted, it could lead to an additional 320 million tonnes of maize each year. This surplus could provide enough calories to sustain 1.3 billion people for a year, addressing the needs of the 700 million individuals facing food insecurity without necessitating the expansion of farmland. Furthermore, as climate change threatens to reduce maize yields by 24% by 2030, EW could serve as an effective strategy to safeguard our food supply.

Can Enhanced Rock Weathering Save Us?

So, is it possible for EW to save the world? While it may not be a complete solution, it offers a hopeful perspective. There is already sufficient food available to nourish the global population; starvation often results from systemic choices. However, EW still faces challenges before it can be broadly implemented, particularly regarding basalt sourcing. Nevertheless, these promising results provide a glimpse of hope that the future may be brighter than we anticipate.

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