I recently talked about what scientists are planninguse the ocean to clear the atmosphere of greenhouse gases using phytoplankton. But, in addition to plankton, there is also another technology in the future - the use of rocks that absorb carbon in the ocean. In general, this is a natural process - as a result of erosion of the coastline, as well as under the influence of waves, rocks enter the water. The stone reacts with water to absorb CO2 from the atmosphere. However, the reaction takes a relatively short time, since water comes into contact only with the surface of the rock. In order for the reaction to continue, the surface of the stone must be periodically cleaned. Scientists propose increasing the alkalinity of the water, which will clean the surface of the rocks that absorb CO2. To increase the alkali content of the water, experts suggest filling the ocean floor with dusty silicate or carbonate rocks.
The prospect of containment of global warming by rocks in the ocean
According to Ulf Ribesel, a marine biologist fromCenter for the Study of the Ocean. Helmholtz in Kiel, as a result of natural "weathering" of rocks, the ocean absorbs one gigaton of CO2 per year. If scientists were able to stimulate this process, the ocean could absorb about 100 gigatons of CO2 every year. Considering that CO2 emissions from human activities are 36 gigatons per year, the potential is quite impressive.
In this case, the amount of greenhouse gases inatmosphere every year would begin to decrease. At the same time, countries could spend less on abating greenhouse gas emissions. In addition, increasing the alkalinity of the water would preserve the coral reefs, which are suffering from acidification. However, as usual, everything looks very simple only on paper.
The Dangers of Increasing Alkalinity in the Oceans
According to experts, it is not known how the increasethe alkalinity of the water will affect biodiversity. But the main question that arises for experts is whether the increase in alkali levels will lead to the formation of calcium carbonate. If this happens, the amount of carbon consumed by the ocean will be greatly reduced.
“Calcification may increase in response toan increase in alkalinity, which will reduce the amount of CO2 sequestered. But if calcium stays in the water and alkalinity does not drop again, CO2 stays in the ocean forever. This is our hope, ”says Ulf Ribsell.
Rosalind Ricabi, Faculty Biogeochemistry ProfessorEarth Sciences at Oxford University, has conducted laboratory studies over the past two years to find out if alkalinity increases calcification in cultures of unicellular organisms called coccolithophorids and foraminifera. The result was positive.
“Cells are adversely affected by alkalinity, and that's a good thing. This is evidence that by adding alkali, you reduce the CO2 levels that cells need to photosynthesize, ”says Rosalind Ricabi.
However, some critics fear thatlarge-scale manipulation of the natural systems of the Earth will lead to unpredictable and devastating consequences, such as the introduction of European rabbits to Australia in the 19th century. It can take years to figure out what impact alkali will have on an ecosystem.
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According to experts studyingthe impact of climate change on the oceans, these fears are true. But as humanity has less time to avert an irreversible climate catastrophe, the choice also diminishes.
The Challenges of Containing Global Warming and Ways to Address Them
Even if the process does work,increasing the alkalinity of the oceans can be a titanic task. Mining, processing and transporting minerals will require an industry equivalent to coal mining, experts say, as it takes one to five tons of the mineral to capture one ton of CO2.
“The project is ongoing because there are enough minerals, but it would be a huge undertaking. And should we continue mining in this way at all? " - says Ulf Ribesell.
Limestone is poorly soluble in water.In addition, it has to be mixed with a concentrated CO2 solution, which adds another level of logistics. Quicklime, a by-product of the cement industry, is readily soluble and abundant, but requires limestone to be burned for production, which reduces efficiency in reducing emissions.
The most promising option is olivine,a greenish silicate-based mineral that binds twice as much CO2 as quicklime and four times as much as limestone. Scientists are currently planning to conduct research using this mineral.
“It can be found all over the world, even in Hawaiianbeaches. Mineral mining does not require any chemicals, you just need to mine them. You can use the world's coal mining infrastructure to do this, ”says the CEO of Project Vesta, a Californian company that plans to conduct four field trials of olivine in California's coastal waters.
Large scale alkalization studiesoceans will begin in 2022. That is, very soon we will find out if this technology can be used to stop global warming. The consequences of the latter are making themselves felt every year more and more, so scientists really do not have much time left.