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I won't say that DAC is like Don Quixote's tilting at windmills because that was an imaginary pursuit coming out of his failing sanity. But DAC will be hard to scale practically and economically.

The cause is rightful, justified, and scientifically sound. It struggles, however, to demonstrate pathways to a directly justified economic pursuit. At best benefits will remain indirectly linked to reward and overwhelmingly expensive. Despite the IPCC's reports, we can barely imagine how serious evolving first order, second order, and further consequences will become.

The scenarios painted by the IPCC require aspirational measures to remove CO2 from the atmosphere to half existing levels, i.e. back from 424 ppm in 2023 to 360 ppm in 1996. Quantifying that reduction means ambitiously removing the 36.6 gigatons per year accumulating plus the 15% of existing 1.5 trillion tons of CO2 in today's atmosphere, or 226 gigatons over say 20 years. That adds up to another 11 gigatons annually. The targeted DAC removals could be as much as 45 gigatons annually.

This is where DAC's costs of $230 to $830 per ton become scary. Where does $10-36 trillion annual cost of removal come from? Another solution altogether?

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