Rock “planting” (enhanced rock weathering) on farms, along with emissions reductions, could help meet the IPCC’s key carbon removal target.
Adding crushed volcanic rock to agricultural fields can improve soil and absorb carbon dioxide. It would be more efficient to do so in the hot, humid tropics, according to a new study.
Enhanced rock weathering (ERW) on agricultural land has emerged as an economically and environmentally promising technology with negative emissions.
Key points of improved rock weathering
- With increased rock weathering, a natural geological process is used to store carbon over the long term.
- Global application of 10 tons of basalt dust per hectare of farmland could sequester up to 217 gigatons of carbon dioxide over 75 years, which is above the IPCC’s lowest threshold for carbon removal needed to meet climate change goals and reduce emissions .
- Farms in the tropics have the highest and fastest return on investment.
Farmers can contribute to CO2 removal
Farmers around the world could help the planet meet a key Intergovernmental Panel on Climate Change (IPCC) carbon removal target by mixing crushed volcanic rock into their fields, according to a new study. The study also highlights the hot, humid tropics as the most promising locations for this climate intervention strategy.
The study provides one of the first global estimates of the potential reduction in carbon dioxide emissions from the application of basalt to agricultural fields around the world. It was published in The future of the earththe AGU journal for interdisciplinary research on the past, present and future of our planet and its inhabitants.
Improved rock weathering
This type of weather intervention is referred to as enhanced rock weathering. It uses the weathering process that naturally sequesters carbon dioxide in carbonate minerals. The idea is simple: speed up the weather in such a way that it also benefits people. When used in tandem with reducing emissions, it can help slow climate change.
And it could be a safer choice than other CO2 reduction methods, according to the study authors.
“Increased rock weathering poses fewer risks than other climate interventionssaid S. Hun Baek, a climate scientist at Yale University who led the study. “It also offers some important benefits, like rejuvenating depleted soils and fighting ocean acidification, which may make it more socially desirable.“.
The new study examines the potential of applying crushed basalt, a rapidly weathering rock formed as lava cools, to agricultural fields around the world and shows which regions can mine the rock most efficiently.
An economical method of carbon removal
“There is enormous potential heresaid Noah Planavsky, a geochemist at Yale University and a co-author of the study. “While we still have a lot to learn from a fundamental scientific point of view, there is hope and we need to focus on what we can do from a financial and market perspective.“.
In a previous study, a separate method of calculating carbon removal was used to estimate carbon reduction by 2050. However, the researchers wanted to look beyond national borders and further into the future.
Researchers used a new biogeochemical model to simulate how applying crushed basalt to global croplands would reduce carbon dioxide, to test the sensitivity of enhanced rock weathering to climate, and to identify areas where the method could be more effective.
The study of enhanced rock weathering
The new model simulated increased rock weathering at 1,000 agricultural sites around the world under two emissions scenarios from 2006 to 2080. They found that these agricultural sites would consume 64 gigatonnes of carbon dioxide over the 75-year study period. Extrapolated to all agricultural sectors representing the full potential application of this strategy in the world, up to 217 gigatonnes of carbon could be sequestered over this period.
“Latest IPCC report He said we must remove 100 to 1,000 gigatonnes of carbon and drastically reduce emissions by 2100 to prevent global temperatures from rising by more than a degree and a half.said Baeck. “In terms of global agricultural area, the carbon removal estimates we found are roughly comparable to the low end of the range needed to have any real chance of meeting these climate targets.“.
Because weathering occurs faster in hot and humid environments, enhanced rock weathering would work faster in tropical regions than at higher latitudes, the study points out. Farmers and companies looking to invest in carbon reduction solutions are making profitable and carbon efficient choices by focusing on basalt application in tropical fields.
The model produced another promising result: improved rock weathering performs just as well, if not slightly better, in warmer temperatures. Some other carbon reduction approaches, such as those based on soil organic carbon storage, are becoming less effective as warming progresses.
Improved rock weathering, resistant to climate change
“The enhanced rock weathering is surprisingly resilient to climate changesaid Baeck. “Our results show that it is relatively insensitive to climate change and performs more or less equally under moderate and severe global warming scenarios. This gives us confidence in its potential as a long-term strategy.“.
Farmers already apply millions of tons of limestone (a calcium carbonate rock that can be a source or sink of carbon) to their fields to provide nutrients and control soil acidity. So a gradual change in rock type could mean a smooth transition to using improved rock for large-scale weathering, Planavsky said.
Improved rock weathering is used on small scale on farms around the world. The next step is to click on a “realistic implementationsaid Planavsky.
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