Will carbon removal be pivotal in mitigating climate change?

What counts as carbon removal?

Direct-air carbon capture a la stripe.com/climate.

The spirit of this prediction is for assessing how critical it is to reduce emissions. If carbon capture is expected to get cost-effective enough then reducing emissions now is less critical. Presumably. So anything that permanently un-emits carbon counts. Anything that just prevents emission in the first place, including things like smokestack scrubbing that capture carbon before it's actually emitted, do not count.

By when?

"Eventually." See the next section. But this will resolve on January 1, 2050 at the latest based on scientific consensus.

What does "pivotal" mean?

That carbon removal will end up being responsible for an impactful decrease in atmospheric CO2 concentration -- enough to yield half a degree Celsius less warming than we'd otherwise see.

The idea is to predict whether carbon capture will get cheap enough to do at a big enough scale to matter and be worthwhile.

The atmospheric CO2 decrease doesn't have to have happened by 2050.


  1. Early on, after discussion in the comments, we changed the criterion to be about atmospheric CO2 concentrations rather than temperature.

  2. This was originally meant to resolve in a few years based on scientific consensus but then Manifold added loans. Now betting in very long-term markets is perfectly incentive-compatible so we'll wait till we're certain about this to resolve it (latest 2050).

  3. Originally there was some ambiguity about whether the full CO2 decrease had to be achieved by 2050. The answer is no, we just need scientific consensus that we're on track for removing that much CO2.

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I dont care enough about climate change to change my daily life. Do you?

bought Ṁ20 of NO

I can't see the capital costs coming down enough to make this feasible, even over 30 years. That kind of engineering improvement, at the scale needed to make a significant difference, just seems wildly unlikely. I think this market is currently way too high (75%), but I'm not willing to commit enough money to shift the odds significantly because of the resolution date (odds on Manifold still existing in 35 years, anyone?)

Since we already have a highly efficient carbon capture mechanism that for some reason is frequently overlooked - does dumping botanical (processed or unprocessed) waste in empty coal mines count?

@Brooster Huh. I asked GPT-4 and it worries that that would produce methane. What do you think?

@dreev So my fundamental prior here is that plants are already highly efficient and low-cost solar energy storage, and people like them more than solar panels anyway.

Assuming there was no pressure or processing collecting large quantities of biomass could produce methane, absolutely, although it might be relatively slow given the sheer mass of compost in question - we might make YoY gains assuming we can combust generated methane. Potential mitigating strategies include use of temperature extremes to impede decomposition - extremes of cold or heat will both work

  • geothermal energy

    • pump steam through a "mine" until it exceeds the boiling point. drill circulation loop into bedrock, monitor heat flux and maintain temperature

      • external water might be used here - if so, seawater could be desalinated concomitantly through a unified process and the salt + biomass stored together

  • freezing - along the lines of the Svalbard seed vault - send trains loaded with biomass to Canada/Siberia during midwinter, deposit biomass cooled by ambient temps, cool "mine" by ventilation in winter, seal off in summer.

  • desiccation may be an option, but is not terribly scalable

Alternatively,it is possible to destructively distill biomass, heating it in the absence of oxygen, reducing it to (comparatively pure) carbon. I feel like this could be a great use of excess renewables during surges or in lieu of sufficient storage. Products would be charcoal + VOCs


  • Can serve as an emergency energy stockpile

    • effectively "re-filling the coal mines"

    • transferring energy reserves from defector/high-emission nations to cooperator/green nations (in case you need to sell the idea to conservatives).

  • yield green, renewable useful organic volatiles

    • can be safely combusted to mitigate gases like methane

    • or, collected and sold to chemical interests.

  • serve as a post-food agricultural industry

    • thus ensuring geoengineering will support heritage occupations

    • displacing food as an agricultural product in project districts

This grew in the process of replying, and admittedly much of this is speculative but it seems to me it would be worth investigating whether we can assemble the pieces we already possess in a superior configuration rather than needing to reinvent the wheel. Also offers the potential for lower ecological impact, as the biomass is source-agnostic, and could include agri/food waste, forestry waste, algal blooms collected from hydropower in/outflows, etc. Dedicated land use is potentially minimal.

Gonna end it here, got a bit overzealous, it seems! 😅

sold Ṁ489 of NO

See discussion below on clarifying a key ambiguity about whether this is asking about mitigation by 2050 or consensus by 2050 of eventual mitigation. I just sold all my shares since this will probably require a judgment call to disambiguate.

predicts YES

@dreev I'm still not clear on when this closes. "Will carbon removal be pivotal?" can only be answered in 2050 (or earlier if actually observably mitigated earlier) if it was indeed pivotal. I would append "by 2050" to the question title in that case. If it's "Will scientific consensus be that carbon removal will be pivotal?" that's a different question. Another different question would be "Will scientific consensus be that carbon removal WAS pivotal?" etc.

bought Ṁ25 of NO

It doesn't sound like much, but half a degree of warming is a lot. For this to resolve YES, carbon capture and sequestration technology would have to become hundreds of times more efficient over the course of 27 years, all while climate feedback loops and a continued reliance on fossil fuels make it very, very difficult to combat warming - especially because carbon capture doesn't affect atmospheric methane levels.

I'm not a doomer or anything, and I understand why people are optimistic, but this is way, way overpriced. If anything changes the current trajectory and causes warming by 2050 to be 0.5 C lower than projected, it'll be rapid divestment from fossil fuels and intense investment in renewables.

predicts YES

@evergreenemily Based on my reading of the question, it is not required that there be a -0.5 C deviation from projections by 2050, but rather that an analysis in 2050 projects that carbon removal will result in a -0.5 C deviation from the scenario of no carbon removal.

predicts NO

@ArunJohnson That is not my reading at all. As far as I, and I think most other traders are concerned, all talk about 'trying to predict' refers to the present, and the value of the prediction market itself. @dreev , can you please clarify?

predicts YES

By the year 2050.

Scientific consensus that carbon removal will end up being responsible for an impactful decrease in atmospheric CO2 concentration -- enough to yield half a degree Celsius less warming than we'd otherwise see.

Yeah it does seem unclear whether it's

"consensus that it is responsible for half a degree less" by 2050, or

by 2050, a "consensus that it will end up being responsible for half a degree less"

predicts NO

@jack Clarification on that from the creator would definitely be helpful, yeah. I think the latter is significantly more likely than the former.

predicts NO

@jack @evergreenemily @AngolaMaldives @ArunJohnson Important clarification here; thank you! I believe I intended "a consensus by 2050 that direct-air carbon capture will eventually be responsible for half a degree less warming".

And on first re-reading that sounds like what the market description literally says: "Pivotal by 2050" and then for defining "pivotal" it says "scientific consensus on eventual decreased warming".

But I see how you can get the opposite interpretation. The title refers to actually mitigating climate change and so the "by 2050" would lead you to believe that actual mitigation should've happened by then. The "scientific consensus that carbon removal will end up being..." in the definition of "pivotal" could be read as "scientific consensus that carbon removal will have been..." or "scientific consensus that carbon removal has been...". I.e., the "will end up being" could seem to be from our perspective now, not scientists' perspective in 2050. I think it would've needed the "will have been" or "has been" phrasing for that interpretation to be legit but I certainly appreciate the confusion now!

Another potential way to address this is to consider which version makes the most sense for the spirit of the question. Half a degree less cooling thanks to carbon capture by 2050 seems like a pretty huge and pivotal mitigation that implies a decent chance of fully mitigating climate change long term despite business-as-usual emissions. Half a degree less cooling ever seems like something that might or might not turn out to be pivotal.

So, oof, yeah, this is really tricky. Eager to hear more thoughts.

PS: Let's say that we want this market's question to approximate the following:

Assume that business-as-usual emissions with no carbon capture will result in certain climate catastrophe costing society $X. Also assume drastic emissions reduction would avert the catastrophe and cost $Y. What's the probability that business as usual plus carbon capture averts the catastrophe at a cost of less than both $X and $Y?

Which interpretation of "pivotal by 2050" does a better job of approximating that question?

PPS: And maybe a simpler version of that is "will carbon capture be both widely deployed and, per scientific consensus in 2050, eventually pay for itself in terms of mitigation of climate change consequences, compared to a counterfactual with no carbon capture?"

Ok, for lack of objections, I've clarified in the description that it's the "eventually" version. Thanks everyone!

I would definitely prefer the criterion be based on CO2 concentration rather than temperature. It looks easier to attribute, and makes the counterfactual less tangled with other potential interventions.

For example, we could mitigate temperature specifically with anti-housewarming gas. Then the counterfactual of this question would yield up 0°C difference due to carbon capture because, if we didn't use carbon capture, we would have regulated temperature by doing more anti-housewarming emission.

A solution could be to specify "no carbon capture, holding the rest fixed". It is difficult, however, to translate "holding the rest fixed" to a satisfactorily clear and unambiguous condition. Defining the counterfactual on something which is a more direct effect of carbon capture, i.e., CO2 concentration, provides a more easily resolvable criterion with less caveats.

predicts NO

@rotatingpaguro Sounds good. Let's call it official that CO2 concentration is the metric now. I'll update the description.

@dreev I don't like your wording:

"Scientific consensus that carbon removal will end up being responsible for an impactful decrease in atmospheric CO2 concentration -- enough to yield half a degree Celsius less warming than we'd otherwise see."

This is still anchored to the temperature difference. I think you should convert right now the 0.5°C threshold to a CO2 ppm threshold, and then fix that as resolution criterion.

predicts NO

@rotatingpaguro Oops, I didn't jump on this when you suggested it. Sorry! But I don't think it matters so much because there's a standard conversion, I believe, for how CO2 translates to warming. So the market is explicitly about CO2 concentration now. How much CO2? The amount that translates to half a degree of warming. If we can agree on what that amount is, then we could still swap that in and leave temperature out of it altogether, which I agree would be cleaner.

predicts YES

@dreev Mitigating climate change is the point, not necessarily CO2 concentration. We shouldn't Goodhart this. A separate market can be made asking how much CO2 is expected to be removed by 2050.

Starting a family of related markets:

bought Ṁ20 of NO

The only real effective carbon capture is when it is attached to the source of the emissions like in a coal fired power plant for example and those will be phased out anyway in tackling climate change. Otherwise the amount of air you have to move to remove the CO2 is too big as CO2 concentration in the atmosphere is like 0.04%. I think that in terms of direct atmospheric modification that the geoengineering solutions are likely to be orders of magnitude more effective.

predicts YES

@JemBishop You could also remove bicarbonate from seawater which might be more promising — and scale faster.