Enhanced Rock Weathering
Rock weathering is a natural phenomenon where rain erodes away rock and reacts with it to sequester carbon dioxide amongst other things. Enhanced weathering is simply when us humans attempt to accelerate the process by carefully picking which rocks to use and then grinding them up to the size of sand particles or to a powder substance, and spreading it in specific spaces, most commonly on crops or shores. Rock weathering can have many positive environmental benefits if used properly, but the mitigation option was recently put into the spotlight and requires more research.
Choosing rocks rich with elements like calcium, silicate, and magnesium create helpful compounds when reacting with rain. Rain often gathers carbon dioxide on the way from the sky to the ground creating a solution of carbonic acid. The reaction between this solution and rocks rich in the aforementioned elements produces bicarbonate, calcium ions, and other compounds. Bicarbonate functions as a carbon sequester for hundreds of thousands of years. Therefore, with careful consideration of rocks, enhanced rock weathering can produce many useful compounds.
Using the ground rock on crops has proved to fertilize the soil, increase pH in the soil, and prevent pests and diseases. Essentially, this increases production yield and simultaneously sequesters more carbon dioxide from the air. Using the ground rock on shores could help sequester carbon dioxide at the bottom of the ocean and decrease ocean acidity, almost killing two birds with one stone. Therefore, enhanced rock weathering is a good multitasking mitigation option.
However, it is important to note its shortcomings. Firstly, mining and grinding the amount of rock in question is energy-intensive, which could lead to even more resource depletion and emissions due to energy production unless more renewable energy is used. Secondly, there is much uncertainty regarding the amount of CO2 that this process would be able to sequester, and it is highly possible that it may need to be paired with other carbon sequestration options to fully capture human carbon dioxide emissions, but this is not uncommon amongst the carbon-capturing options currently available. Lastly, limited research has been done on this mitigation option, and it has mostly focused on other benefits than carbon sequestration. This means that more research is still needed, and more importantly, the application of this must be tested and researched. Luckily this is happening both for shore and crop applications and results will hopefully be seen soon.
In conclusion, enhanced rock weathering is a way for us humans to accelerate a highly beneficial natural phenomenon. The applications of this process are wide and have many benefits ranging from increased crop efficiency to increased carbon sequestration. The mitigation option has some downsides and needs more research to truly evaluate its efficiency and value. However, enhanced rock weathering has true potential and may be a good option to consider.
Written by Zein Tynon, Class of 2024.
Beerling, David, and Stephen Long. “Guest Post: How ‘Enhanced Weathering’ Could Slow Climate Change and Boost Crop Yields.” Carbon Brief, July 9, 2020. https://www.carbonbrief.org/guest-post-how-enhanced-weathering-could-slow-climate-change-and-boost-crop-yields.
Evers, Jeannie, ed. “Weathering.” National Geographic Society, October 9, 2012. https://www.nationalgeographic.org/encyclopedia/weathering/.
Lehmann, Johannes, and Angela Possinger. “Removal of Atmospheric CO2 by Rock Weathering Holds Promise for Mitigating Climate Change.” Nature News. Nature Publishing Group, July 8, 2020. https://www.nature.com/articles/d41586-020-01965-7.
Temple, James. “How Green Sand Could Capture Billions of Tons of Carbon Dioxide.” A Caribbean beach could offer a crucial test in the fight to slow climate change. MIT Technology Review, June 27, 2020. https://www.technologyreview.com/2020/06/22/1004218/how-green-sand-could-capture-billions-of-tons-of-carbon-dioxide/amp/.