This blog post discusses the potential of enhanced rock weathering, particularly using basalt from volcanoes like Mount Teide, as a method to combat climate change by sequestering carbon dioxide. It outlines the natural process of rock weathering, the benefits and challenges of enhanced rock weathering, and its potential impact on global carbon levels.
The Canary Islands are home to Mount Teide, one of the world’s largest active volcanoes. Capable of spewing tens of millions of cubic meters of lava in a single eruption, Teide’s destructive power is significant. However, there is a fascinating proposition that suggests we could harness the basalt rock inside Teide to help save humanity from climate change. This idea revolves around the concept of enhanced rock weathering, a method that could potentially offset Earth’s emissions for the foreseeable future.
Enhanced rock weathering is a theoretical scheme that aims to accelerate a natural process known as rock weathering. This process occurs whenever it rains. As rainwater falls, it mixes with atmospheric carbon dioxide, forming a weak acid that can dissolve minerals called silicates. Since silicates are present in over 90% of Earth’s exposed rock, this weathering process happens almost everywhere rain hits stone.
As the acid reacts with the rock, the dissolved carbon dioxide in the rainwater transforms into bicarbonate, which then trickles downstream to the ocean. Marine organisms utilize this bicarbonate to create structures like shells. When these organisms die, their shells sink to the seafloor, effectively trapping carbon dioxide in the ocean for millennia. This natural process has a significant impact on Earth's climate, as it helps regulate atmospheric carbon levels.
The rate of rock weathering is influenced by two major factors: the types of rock exposed to weathering and the amount of rock that is exposed. Silicates that form at higher temperatures tend to weather faster due to their chemical composition. This includes volcanic rocks like basalt, which are abundant in regions with active volcanism.
However, when these rocks are piled up in a mountain, not much of the rock is exposed to the elements. To address this limitation, climate experts propose that we should harvest fast-weathering rocks, crush them, and spread them out to increase the rate of weathering. This approach is known as enhanced rock weathering and is considered one of the most practical strategies for drawing down atmospheric carbon.
One of the advantages of enhanced rock weathering is that it does not require the invention of new technologies; instead, it can utilize existing systems for mining and processing rock. Additionally, agricultural communities have long recognized that volcanic rocks and soils can enhance crop yields, making farmlands ideal sites for dispersing crushed basalt.
For enhanced rock weathering to have a significant impact, it must be implemented on a global scale. Simulations indicate that a worldwide program spreading 10 tons of basalt dust on every hectare of farmland could sequester over 200 gigatons of CO2 over a 75-year period. These figures highlight the potential effectiveness of this approach, especially considering its low cost and practicality.
Despite its promise, enhanced rock weathering is not without challenges. First, the process runs through the entire global water cycle, which is influenced by numerous variables. This complexity makes it difficult to measure the precise impact of enhanced rock weathering.
Second, while existing mining technology can facilitate the quarrying and processing of rock, the scale of the operation presents significant ecological and engineering challenges. Quarrying, crushing, transporting, and spreading vast amounts of rock would require substantial resources and energy. If the energy used for these tasks is not sourced from clean energy, it could negate the carbon benefits of the project.
Finally, any large-scale intervention in Earth’s natural systems may lead to unpredictable side effects. For instance, quarried rocks could contain hazardous heavy metals or other unknown elements that could pose environmental risks.
The challenges associated with enhanced rock weathering should not deter us from exploring this promising strategy. Instead, they should be viewed as initial obstacles to overcome. The potential benefits of enhanced rock weathering in combating climate change are significant, and with careful planning and execution, it could provide a viable solution to help mitigate the effects of global warming. Ultimately, we may not need to blow up a mountain to make a big impact; instead, we can leverage the power of rocks to help save our planet.
