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It's hard for people to visualize removing tons or billions of tons of carbon dioxide (CO₂). I propose we talk about CO₂ removal (#CDR) like a time machine (e.g., this machine will take us back 5 minutes). For example:
Q: How far back in time does planting 100 million trees take us?
A: If one mature tree takes up an average of 25 kg of CO₂ per year, then 100 million trees will take up 2.5 MtCO₂. That's a time machine that takes us back 33 minutes and 6 seconds in a year. It's not a lot.
Another CO₂ removal (CDR) as time machine example:
H&M, the second largest international clothing retailer, recently purchased 10,000 tonnes of CO₂ removal from Climeworks. 10,000 tonnes sounds like a lot, right, but it's a time machine that takes us back only 8 seconds. 
https://hmgroup.com/news/hm-group-further-invests-in-the-decarbonisation-of-its-value-chain/
My #CDR friends on twitter got mad at me for pointing out that the four regional Direct Air Capture (#DAC) Hubs under the Inflation Reduction Act (#IRA) specify a minimum CO₂ removal capacity of 50,000 tonnes/year.
Hence, each DAC Hub is a #time #machine that takes us back only about 40 seconds a year!
It's important to point this out because some people think CDR is a replacement for #decarbonization and that can never be the case.
https://www.energy.gov/oced/four-regional-clean-direct-air-capture-hubs
@davidho
Thank you. This is the kind of communication needed from scientists to help the public appreciate what is feasible and meaningful ... versus hype to foster denial and sleep.
@davidho OMG. What a number!
I actually need some effort to conceptualize this #number as well!
So 100 million is 1e8. It's a square, 10k #trees by 10k. Assuming a #pine plantation with ~2 m between trees, it's 20x20km of pines. A HUGE one!
And assuming that we then chop them all down and hide them in a mine, to sequester #carbon, it's some 30 years of growth = (by your calculation) 15 hours of #co2 release at a current rate? Not even a full day! omfg.
+bonifartius 𒂼𒄄 @ampanmdagaba @davidho
ok, we emit 37 040 000 000 tonnes CO2 yearly (37.04 billion tonnes).
given your numbers i come up with a forest of about 2434km edge length:
> puts [ expr sqrt((37040000000 / 2500000.0) * (20 * 20)) ]
2434.4198487524704
restore mother europe to be a continuous forest as she has been.
let's go.
@bonifartius @ampanmdagaba @davidho You could do this even more effectively by restoring Australia’s Eucalyptus Regnans groves. Each tree can grow to 90 meters tall, at a rate of 2 meters per year, culminating in tens of tons of sequestered carbon. Whilst also flowering, providing habitat and nourishment for millions of living things.
@davidho
Brilliant!
Now picture 1 single coal power plant and its annual emissions, say 1Mt?
If you want to remove its lifetime emissions since 1990 via #DACS, you need to build 1000
#Climeworks plants (while all machinery and transport means are burning fossil fuels?)
PLUS required electricity capacity,
and run these 1000 DACs factories for 30 years to capture it all from 1 single coal pp, 15 if only half.
Build another 1000 DACS
for 1 batch of 1mio cars. 1bn are on global roads in 2020
@anlomedad_real @davidho
Pyrolyzing and burying 10 percent of the world’s annual biomass waste as #Biochar could sequester nearly five gigatons of carbon annually, #JustSayin
First step is to stop burning fossil fuels and then we've got to drawdown the pollution we've already contaminated our thin, precious atmosphere and oceans with.
Humans are emitting roughly 28 gigatons per year of CO2 so all of our immediate focus needs to be on stopping to burn fossil fuels.
plus the trees - once more mature as in 20 to 30 years after planting - are only a part of the process as lichen, moss & a diverse understory are needed
planted trees are not a forest
@davidho stop eating animals if you really want change.
@davidho That not the whole story though - trees also give us oxygen, regulate temperatures by up to 10 degrees, create atmospheric moisture and support untold biodiversity networks. 10 million more would start to help a lot. 100 million more even more so, especially in 20 years time. Best time to plant a tree 20 years ago, second best time today. They are no substitute for slashing carbon emissions though - that’s up to us.
@pineconeclare @davidho the problem with "planting trees" as a concept is that even if you don't plant trees, they will still grow. Anywhere that a tree wild naturally survive for a couple of decades, if you just leave that space alone trees will grow by themselves. So the marginal impact of "planting trees" is mostly nil. Actually changing land use from things like grazing to forest certainly has good impacts, but that's not what most "plant a tree" initiatives are doing.
@tiotasram @pineconeclare @davidho
It's complex, as the maximum C storage occurs in pastured grassland with a moderate tree density (or a very open forest, if you prefer the glass half full 
).
Soil is a much greater C reservoir than trer biomass, and grass roots pump huge amounts of C into belowground. Plus, the photosynthetically fixed C in a mature forest reaches often almost an equilibrium with decomposition. Younger trees fix larger quantities.
But I agree totally: ecological (biodiverse) ecosystem management instead of agricultural extractivism would be a good idea 
@earthworm @pineconeclare @davidho thanks for the more nuanced version of this take! I picked grazing on part because of its connections to agriculture but indeed properly managed biodiverse grassland is definitely not something we should be converting to forest.
@pineconeclare @davidho I think the point of the post is not, that we shouldn't plant any trees, but that companies that try to look sustainable, by doing that don't change anything without also changing their way of production.
@pineconeclare @davidho most if what you mentioned come from an healthy forest, not individual trees. If a company have an agreement to plant tree for 20 years, they probably have a plan to cut down theses trees and sell the wood at the end of the 20 years to increase their ROI.
@davidho
@terliwetter @rahmstorf This proposal makes #CO2 savings/removal far more tangible to the average person
@anlomedad_real
@davidho great way to visualise the topic. I will adopt it
@davidho
I wonder how far back in time would taxing the top 100 billionaires take us? #taxtherich
@davidho
While #HandM H&M's press release describes a few new biz processes that probably really reduce their current emissions,
their engagement with #Climeworks is worded a bit foggy: likely meant to "reduce" continued emissions. But it cd mean – and *should mean* – that they're beginning to clean up their old #CO2 debt.
A girl hopes that biz people and people in politics get their act together and stop greenwashing alleged "reductions". Change in behaviour and biz processes is inevitable.
@davidho Texas can do it for a lot of DACs ;) Extensive Capture was our “do very little and clean it all up with DACs” pathway to net zero. It ain’t nothing!
https://cockrell.utexas.edu/images/pdfs/UT_Texas_Net_Zero_by_2050_April2022_Full_Report.pdf
@JoshuaRhodes every house in TX will be a DAC hub.
@davidho does that finally make the grid smart?
@JoshuaRhodes Not if every hub is generating its own electricity. 
@davidho Thanks. Excellent thread.
Technological CDR is a total scam...
Every dollar invested and every minute wasted discussing it just removes resources from the most meaningful and effective we can do: stop burning the planet for a few bucks for people that are already so rich they can't spend their wealth in lifetime.
There are several mechanisms why CDR receives so much more funding than reasonable actions:
- CDR doesn't touch the status quo
- the easiest thing for governments is to spend money instead of forcing people/companies to actually change behaviour
- scientists/engineering enthusiasts like the idea of a technology to 'save the world'
- there are plenty of business opportunities and money to make
With 'green CDR' the things might be a little bit different, especially when these initiatives involve a bottom-up improvement of livelihoods of the people. I am not referring to industrialized afforestation projects (!), like the ones usually offered by most offsetting companied, but to initiatives like https://www.evergreening.org/
Or improvements of agricultural techniques benefitting resilience, biodiversity and soil organic matter contents.
@davidho if it only manages to reduce such a small amount, what sense does it make to pursue it now? why not wait until the system becomes more impactful? Honest question.
@mdione @davidho if you do the math on direct air capture based purely on the thermodynamics of extracting co2 from air you'd need something like >5% of the world energy production to make a dent at reasonable timescales, assuming perfect efficiency with 0 losses
it's just not practical without some entirely different approach *and* real decarbonization
@davidho But 50,000 tonnes sounds like a lot!
@davidho so we need "only" 33,000 to offset yearly global emissions?
@davidho It is absolutely insane to me how we cannot grasp this : we have been taking carbon out of the ground it was buried in for hundreds millions of years. We have been doing this at an ever increasing rate for two centuries with coal, oil and gas (we never globaly stopped coal).
This inactive storage was the reason we are not living in a huge dinosaurs and giant forests era.
How can we think planting trees on the available surface and petrifying a bit of soil (DAC) will offset this ?! How?
@davidho This is a really neat way to show individual actions in a larger picture, thanks for this.
In H&M's case this could be imagined to be related to recent news of their very environmentally destructive practices, this time in regard to recycling.
So classic #greenwashing whereas it is their business model of fast fashion that is the underlying problem.
@davidho Climeworks sold so many of those tons, they must all be long term forwards...
@davidho @TatianaIlyina This is an observation one can make again and again. Most people can't handle large number, even less numbers of different orders of magnitude. I like your example very much!
@davidho Assuming we also stop cutting down the trees we already have, I presume 
@davidho This is a great communications tool. I find each announcement to be incomprehensible as to its benefit in real terms. They keep saying a project's effect is like taking x number of cars off the road but that is also hard to comprehend. Your idea makes a project's effect easier to convey and get behind.
@davidho would it be possible to add references for tree CO2 uptake and for yearly global CO2 emissions?
I wonder how much my garden can contribute.
@davidho I had to write this every time someone talks about urban trees as a solution to climate change https://badmomgoodmom.blogspot.com/2022/12/urban-trees-and-zombie-carbon.html
@davidho great way to communicate! And it’s important to understand that trees don’t mature in 33 minutes.
@davidho Let's take this calculation a stage further. If every person on earth planted a tree that would turn back the climate time machine back almost two days. https://mastodon.world/@davidho/109511745525784891
@davidho I'm belatedly seeing this. Thank you for this thread!
(Hmm what other great threads is Mastodon hiding from me...)
@davidho since the carbon cycle is different for every tree species as well as between different forests - this estimate is worth even less …while also being kind of a cool illustration of the inadequacy of business accounting concepts as a tool for valuing ecological dynamics !
@davidho I really like that analogy. Another way of thinking about that 33 minutes and 6 seconds: Across all of humanity that delays the climate crisis by 470 thousand years of life ((33×60+6)×7.5×10^9÷(60×60×24×365)). So both miserably inadequate and ridiculously valuable.
@davidho Great way to communicate. About 20 us (microseconds) per tree is a number I will remember :)
That's the truth.
We exaggerate these kinda measures, because we like to believe, that this is an "easy way" to get rid of the problem. It's not, it's only a small contribution; nevertheless, let's do it...
If “Cutting animal-based foods in US diet by half could prevent 1.6 billion tons of GHG emissions by 2030” https://news.umich.edu/cutting-animal-based-foods-in-us-diet-by-half-could-prevent-1-6-billion-tons-of-ghg-emissions-by-2030/ then maybe we should be changing our diet AND planting trees!
Please read:
*Eating our way to extinction https://www.youtube.com/watch?v=LaPge01NQTQ&t=10s
Also, trees might not be the most effective natural CO2 sync:
Mangroves, seagrass & salt marshes comprise "blue carbon" ecosystems that can sequester up to 4 times as much CO2 as terrestrial forests are vital to the world meeting the Paris climate accords.
https://www.theguardian.com/environment/2021/nov/04/can-blue-carbon-make-offsetting-work-these-pioneers-think-so &
https://www.wri.org/insights/turning-tide-ocean-based-solutions-could-close-emission-gap-21 &
https://oceanservice.noaa.gov/ecosystems/coastal-blue-carbon/
@davidho i love this. How well does capturing our global food production byproducts do? (like, say, if we were to lock up all rice/wheat/barley/oat straw inside the walls of all our buildings?)
@davidho (Authors Bruce King and Chris Magwood claim in Build Beyond Zero (pg 118) that it’d be comparable to global transpirtation emissions, or more. Would love to know what that looks like when run through the flux capacitor 
@davidho Provided they all actually grow to maturity, which it's very unlikely they will. You'd need to plant about billion trees, and tend them reasonably well, to be assured of 100,000 mature trees.
@davidho
Ecosia is a search engine based in Germany. Ecosia considers itself a social business, claiming to be CO₂-negative, supporting full financial transparency, and protecting the privacy of its users. Ecosia is B Lab certified, meeting its standards of accountability, sustainability, and performance. As of March 2023, the company claims to have planted more than 170 million trees since its inception.
Ecosia uses 80% of its profits to support tree-planting projects
https://www.ecosia.org
@davidho In fact it is far easier and effective to produce LESS CO2 than "remove" it....
@davidho There is no consumer or public level activism thst can have a positive enough impact on Anthropogenic Global Climate Change to make it worth doing.
@davidho Nothing tech can provide will help. The only thing possible is a massive reduction in generating power and in transportation -- and there is no sign these things are even on the table.
@stoicmike @davidho consumer action could dramatically reduce plastic waste pollution
@davidho that's really useful!
And depressing 
(Though compared to a lot of the other examples down-thread, 00:33:06 is really good!)