The Earth's carbon cycle manages about 750 gigatons of CO2/year and humans are emitting ~30 excess gigatons a year on top. The diatoms in the ocean are happily out there processing 150 gigatons of CO2/year, but what we need to engineer is only 30 gigatons (to completely eradicate human emissions).
If we engineered diatoms to fix, say, 0.3 gigatons/year, we'd eradicate a whole integer percent of our emissions.
Heck, if we got it in the 0.03 gigatons (30 megatons/year), we've probably built something scalable and created a useful entry in our portfolio to capture carbon, sinking about 0.1% of our carbon/year.
So, don't despair, we don't have to compete with the ocean! We only need to compete with ourselves! Or maybe do despair? Because we have to compete with ourselves... fundamentally, climate change isn't a technology problem, it's a political problem.
Our yearly emissions are 36GT and ever growing modulo a reprieve in COVID. It was only about 20 just 17 years ago. That means you need to sequester more and more every year just to keep a constant percentage of sequestration. If you include deforestation and wildfires, this number goes up to 41GT which means there’s a compound effect since current models suggest that’s part of a negative feedback loop (ie worse due to our actions and global warming).
Perhaps more importantly, the 750GT number you cited (whatever the real number happens to be) is 1.5x larger than before we started burning fossil fuels at scale. So to get the world back to where it was, not only do we need to overcome our yearly expenditure, we’d have to pay back a lot of CO2 emissions debt we’ve spent building our economy and even 10 GT/year won’t pay back nearly three centuries worth of exponentially increasing emissions on any meaningful time frame once the world is at net 0.
All of this is ignoring the practical realities of scaling carbon sequestration up in a way that’s net positive and even mildly profitable or at least not expensive enough that it doesn’t become a collective action problem.
I’d be the first to celebrate if this were an actual solution, but unfortunately I think carbon sequestration won’t be a meaningful effort to even think about in practical terms until we’re meaningfully on our way to net 0 and we’re well off from that with politicians thinking about maybe banning fossil fuel car sales in 2035 which means it’ll take until 2050 or so for a meaningful percentage of fossil fuel cars to start leaving the road. And ignoring the manufacturing challenges about producing so many batteries (which I think we will probably solve), we’re nowhere close to solving decarbonization of shipping and aviation and don’t have line of sight on the big whale of the energy grid which is responsible for >70% of all emissions (yes yes solar - but worldwide emissions from the energy grid keep going up and we haven’t even made a dent in the second order derivative and maybe just in the third order if you’re optimistic with every indication that we’d actually need nuclear to change the calculus in the short term).
https://earthobservatory.nasa.gov/images/152519/emissions-fr...
Around my place people burned witches for 400 years - to fight lightning strikes.
Removing gigatons of CO2 is maybe on the same level - only more stupid - and bad for plants. Arguments against witch burning didn't have much data to process. For CO2 there's quite some number crunching out there available...
Emotions, despair, anger, ... these are a lot of emotional arguments in the media out there. People should be more cool and only care about the physic and mathematics... And actually read some papers - not this emotional science fluff from the media.
Good question. Answering questions is called 'research'. ;-)
I'm skeptical for the same reasons as you, too. Let's see... the ocean covers 361km^2. If we could engineer a material with "cells" that were 1000x as effective at carbon capture as diatoms, and the manufactured material was 1000x more densely packed together than diatoms are on the ocean surface, then you'd need 361 square kilometers of the magic material. Which is not out of the realm of possibility, though I have no idea what the density of diatoms is and I have a sneaking suspicion that we'd be looking at more of the 3x-4x range of efficiency improvement. And of course, you need to turn the CO2 into something and deposit it somewhere, and maybe move it around lot. Which would use energy that would produce more CO2, offsetting the gains. Oh, and manufacture the stuff.
I'm thinking releasing less of the stuff and stopping forest destruction might be much more effective for a long time here...
That should of course be 361 million km^2.
The industry will look for a profit motive to solve this. The scientists will look for a publication and fame motive. The politicians will try to grab more power. The poor animals and other third world country people who had nothing to do with this will bear the brunt. Only time will tell.
Though probably one can try to create an artificial wind, blowing CO2-free air away so CO2 could move quickly into the freed space.
In all likelihood, we can get ~10x better efficiency without trying very hard.
Living beings don't focus much on growing. They are usually less than 1% efficient on that, with more complex life being on the order of 0.1% efficient.
The key point of this paper with respect to synthetic industrial photosynthesis:
> "Reaction-diffusion modeling of C. reinhardtii suggests that all pyrenoid-based CCMs require the following essential features: (1) aggregation of most of the chloroplast’s Rubisco enzymes, (2) a local source of high CO2 concentration at the center of this Rubisco aggregate, and (3) a diffusion barrier at the aggregate border to prevent CO2 leakage. Our data indicate that the PyShell contributes to the first two essential pyrenoid features (Figure 5A), and we wonder whether the PyShell may directly perform the third (Figure 5B)."
A big difference between oceanic diatoms and land plants is that the former's carbon source is bicarbonate, and diatoms convert bicarbonate (HCO3-) to CO2 which is utilized by Rubisco to fix CO2 onto a five carbon sugar which then splits into two 3-carbon species that are fed into carbon metabolism to generate lipids, amino acids, carbohydrates, etc. Increasing CO2 concentration around Rubisco makes the process more efficient (as this keeps out the O2, and avoids futile cycles where the O2 gets added to the target sugar). Some land plants (grasses, cacti) use alternative concentration systems not involving bicarbonate (bundle sheath and CAM).
The real takeaway for industrial-scale synthetic photosynthesis efforts is that it's always more efficient to preconcentrate CO2 into a 100% CO2 stream before feeding it into a reaction process with suitable robust catalysts in which O2 is removed and H2 is added to generate methanol or methane (somewhat analogous to ammonia synthesis) which (if you want to do real long-term storage) can be converted to materials like carbon fiber or diamond.
[] https://en.wikipedia.org/wiki/Diatom#/media/File:Diatoms_Egg...
We can definitely try to increase wheat production by trying to make a GMO. This could be ground breaking for food production.
[1] with the obvious advantage of improving performance by 2 orders of magnitude thus solving Earth's carbon cycle issues
