Exploring Enhanced Weathering for Low-Cost Permanent Carbon Dioxide Removal
Learn about the potential of enhanced weathering for low-cost permanent carbon dioxide removal. Understand the different pathways, challenges for monitoring, reporting, and verification, and the potential of enhanced weathering in fields.
Zeke Hausfather
"A tireless chronicler and commentator on all things climate" -NYTimes. Climate lead @stripe, writer @CarbonBrief, scientist @BerkeleyEarth, IPCC/NCA5 author.
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Rocks are awesome, and enhanced weathering (EW) of mafic or ultramafic rocks like basalt and olivine is a promising pathway for low-cost permanent CDR.
— Zeke Hausfather (@hausfath) June 1, 2023
That being said, there are still major areas of scientific uncertainty that need to be addressed before we go large scale. https://t.co/MReLuadXqv -
There are a number of different proposed pathways for enhanced weathering, but they can generally be divided into two categories: rocks weathering in air and alkalinity enhancement in water. Each have different challenges for monitoring, reporting, and verification (MRV). pic.twitter.com/BRZl50dq5l
— Zeke Hausfather (@hausfath) June 1, 2023 -
Within rocks in air there are two sub-pathways:
— Zeke Hausfather (@hausfath) June 1, 2023
1) Fine grain rocks (usually basalt or olivine) spread in agricultural fields that weathers, forms bicarbonate, and ultimately ends up in the ocean.
2) Accelerating mine tailing weathering that forms stable in-situ carbonates. -
EW in fields has a number of co-benefits, including soil pH management and nutrients. But there are still outstanding questions around accurately measuring the rate of rock weathering, strong acid neutralization, and evasion in streams in rivers: https://t.co/TWAx02gUtF pic.twitter.com/m0wcfMWqCo
— Zeke Hausfather (@hausfath) June 1, 2023 -
Accelerating mine tailing weathering is a bit more expensive today, but also potentially more straightforward from a MRV standpoint as its easier to measure in-situ carbonate formation. https://t.co/5e2ABH3M25 pic.twitter.com/Ik06FzDSR6
— Zeke Hausfather (@hausfath) June 1, 2023 -
Putting rocks (such as olivine) in the ocean is the most uncertain of these pathways today, given large challenges in measuring the weathering rate, air sea gas exchange dynamics, and the risk of triggering runaway secondary precipitation of carbonates: https://t.co/XXA3rfeks4 pic.twitter.com/OAfxaeP1MS
— Zeke Hausfather (@hausfath) June 1, 2023 -
So enhanced weathering is really promising, but we need to be responsible as we explore expanding beyond early stage pilots in place today. For EW to succeed at scale requires us to take MRV seriously and ensure that we take a systems view to accurately verify carbon removed.
— Zeke Hausfather (@hausfath) June 1, 2023