I am a climate scientist, and it isn’t very often that I feel like I get to share good news with people. Luckily, every so often good things actually do happen. I have said on this site a few times before that climate science is relatively young as a field of study, and though things may feel bad at times, some of the best scientists in the world are working in the background to address our major climate issues.
Four years ago right here on Hexbear I was addressing some comrades’ concerns about climate in the long term. I told them that of course the situation we are in really is terrible, but there is one method in particular that has some real potential to majorly address our climate crisis: Silicate weathering. This method has been one of the primary methods of carbon cycle management throughout earth’s history, albeit over time periods of millions of years, and all we have to do is figure out how to apply it to human timescales. Just as I predicted, that is still indeed the most promising method of carbon sequestration, and it just took a giant leap towards viability, as outlined by the study I will be talking about with you today.
(My commentary from 4 years ago if you don’t feel like following the link)
On the, “What can be done?” side, luckily you have some of the smartest and most dedicated scientists in the world working on ways to sequester carbon, and the most promising method is accelerating the silicate weathering process which is the most effective tool to combat man made climate change.
For those who don’t want to read or don’t understand, I’ll briefly summarize why this method is important and the most likely candidate:
You may be thinking “oh let’s plant trees” which is good, sure, but consider that we are re-adding carbon which was not actively in the carbon cycle back into it. A mature forest is most times carbon neutral, as carbon output from decaying biological matter is roughly equal to carbon uptake (think about the following: how could forests continue to exist in the first place if they sucked out more carbon from the air than was added to it?)
Now think where we are getting our carbon that we add back to the atmosphere from. We pull it from underground deposits. The beauty of silicate weathering is that it incorporates carbon into rocks, and thus acts as a long term storage vessel when removing carbon from the atmosphere. The big problem though is that this process happens naturally over the course of tens of millions of years as a result of plate tectonics uplifting mountain ranges and these ranges getting weathered (as implied by the name “silicate weathering”).
So now geologists and climatologists are trying to figure out ways to massively accelerate that process, which has only become a remote possibility over the last 15 years.
How it works: 
What it means in less scientific terms:
Enhanced rock weathering (ERW) in farmland is a method to sequester atmospheric carbon on medium-long term timescales. This study measured this carbon sequestration process as a way of potentially increasing crop yields while simultaneously removing carbon from the atmosphere through the silicate weathering process. Testing this process demonstrated ann improved crop yield of 8%-18% in humid regions, plus improvements in overall soil quality. Soils with higher alkalinity sequestered the most carbon, especially in high precipitation scenarios. Expanding this study to all viable farmland across China has the potential to sequester .4gt of carbon yearly, or roughly 3% of China’s yearly CO2 emissions. Economically, utilizing this method is comparable to the cost of heavy soil modification already used for intensive agriculture. The use of ERW in nutrient poor/overly acidic soils provided a comparable effect to common agricultural practices of using lime and fertilizer to decrease acidity and raise nutrient levels. Additionally, the silicates needed to conduct this process are commonly found in waste products of advanced manufacturing and industrial processes, which could mitigate the carbon impact of manufacturing, industrial, and farming sectors while also lowering expenses in each.
Utilizing this method globally, we have the ability to improve the quality of our farmland while also removing carbon from the atmosphere at relatively fast rates, all things considered. Of course, we will still need to go carbon neutral in terms of energy production, but once that is achieved we have an actual method to remedy some of the harm we have already done to earth’s climate. Our long term climate solutions, should we use this method, are possible on a scale of decades-hundreds of years (and that’s with only our currently available technology!) as opposed to the thousands of years or longer we previously thought.
This is indeed extremely promising. Enhanced weathering is one of the few geoengineering (broadly construed) approaches with some potential. The big problem, as you alluded to, is the production and distribution chain. I haven't read the study yet, but most global-scale approaches to this would require and an extraction and distribution industry similar in size and intensity to the fossil fuel industry. Not only is that challenging to spin up overnight, but it's again hard to do in a way that isn't itself so carbon intensive that it wipes out most of the gains. If our leaders weren't cowards, they'd nationalize all fossil fuel industry companies and tell them "you're extracting and distributing this stuff now," but alas.
Yes, exactly. And we are talking about just using it in farming applications here. What makes this research promising in particular is that it is comparable in cost to intensive agricultural practices for similar results in production. A simple government subsidy could make this an extremely effective climate friendly change where the process is viable.
But like you said, that is frankly only 1/3 of the story. Another piece of the problem is that even if it immediately became cost effective on farmland globally, the mineral extraction process would have to be carbon neutral (or very close to it) to actually begin the process of net carbon removal from the atmosphere.
And the last piece is that even assuming full carbon neutrality in extraction and energy production globally, the rate of carbon sequestration via global agricultural ERW only would not be fast enough to meet humanity’s needs before we start to see some of the worst, baked in impacts of climate change from our cumulative carbon output. While carbon sequestration with profitability in the agricultural sector is nice, we would need to industrialize this process beyond just agriculture, for the sake of carbon sequestration itself.
Which of course brings us to the fact that the future is indeed going to be socialism or barbarism. There is no future in which just sucking up carbon, an inherently unprofitable venture, can exist under capitalism. A socioeconomic order where the wellbeing of humanity is of the highest importance is absolutely necessary to make something like this actually possible.
I'm not sure I understand the question. The claim isn't that 2100 is going to be worse than 2500, but rather just that a certain amount of warming is already "in the pipeline" because the Earth's energy balance hasn't equilibrated to the GHGs already in the atmosphere. Even if we went carbon negative today, we'd still experience some amount of warming unless the removal rate was so high that it could bring the CO2 levels down on a time scale that's smaller than the "catch up" time for the baked-in warming we've already got coming (which is on the order of decades).
This is part of why people don't take carbon capture and sequestration by itself seriously as a solution: unless we can effectively run the whole fossil fuel industrial complex in reverse--removing and sequestering CO2 at the same rate we're now emitting it--even a negative emission rate at this point isn't going to be enough to dodge the serious warming we have coming. And the technology to go that negative that quickly simply does not exist, nor is it even close to existing. This plan is better (and by a fair margin) than anything else suggested so far, but it still doesn't get us anywhere near "silver bullet" territory.
Yep, this is all correct.