Happily, as certain minerals break down, they draw in carbon dioxide. The question is whether we can find ways to speed up that process
Weathering takes places when rainwater hits naturally-occurring minerals and they gradually break down, drawing in carbon dioxide as this happens. Indeed, of the approximately 40bn tonnes of carbon that we emit globally each year, it is estimated that around 1.1bn are already removed through weathering.
Enhanced weathering is a deliberately accelerated version of this natural process. It can take place on land or within oceans.
One way of accelerating the process of weathering his to spread crushed minerals across wide tracts of land. Crushing the minerals first increases their surface area and thus their ability to draw down carbon, but the process itself requires energy, including for the mining, crushing and distribution of the minerals. This makes it expensive.
Crushed basalt rocks - or manufactured forms of alkalinity - can also be distributed directly in the ocean or on adjacent beaches. This process is known as ocean alkalinity enhancement. This approach would have the dual advantage of countering increased ocean acidity, itself a result of rising atmospheric carbon dioxide levels, which is already damaging ocean life. However issues of cost, scale, safety and timeframe remain unanswered.
Project Vesta is at the forefront of research around spreading the mineral, olivine, on the beach. The idea is that this will be broken down by the motion of the waves. Eventually, through several chemical processes and having been incorporated in the shells of sea creatures and corals, carbon will be permanently stored in layers of limestone on the ocean floor. Project Vesta hopes that this process could capture 20 times more carbon dioxide than that created by the extraction and transportation of the olivine and believes that if deployed on just 2% of global shelf seas, could sequester 100% of annual human emissions.