Evergreen

The pathway Enhanced weathering (EW) accelerates a chemical reaction that the Earth already runs at geological pace: the dissolution of silicate rocks by carbonic acid in rainwater. When fast-weathering rocks like basalt, olivine, or wollastonite are crushed to fine particles and spread — usually on cropland, sometimes in rivers, forests, or mine pits — the surface area available for reaction increases by orders of magnitude. CO₂ dissolved in soil water reacts with the minerals, producing dissolved bicarbonate ions that drain through soils to groundwater and eventually the ocean, where the carbon is stored on timescales of 10,000 to 100,000+ years. That long-tailed durability is why EW sits alongside direct air capture and mineralization in most “durable CDR” portfolios, even though it borrows infrastructure (quarries, ag spreaders) from existing industries. ...

Biochar: the pathway Biochar is what you get when you cook biomass — crop residues, forestry waste, sewage sludge — in a low-oxygen environment at several hundred degrees Celsius. The carbon that the plant pulled out of the atmosphere ends up locked in a stable, ring-structured solid that resists microbial decay for centuries when applied to soil or used as a filler in concrete and asphalt. It is, by volume, the largest delivered carbon dioxide removal (CDR) pathway today: biochar accounts for the majority of tonnes actually issued on registries like Puro.earth and the European Biochar Certificate (EBC), even as direct air capture attracts more capital per tonne announced. ...

The premise Biomass burial is the deliberate placement of plant matter — wood chips, agricultural residues, sludges, algae, even whole logs — into an environment where it cannot decompose. The carbon a tree pulled from the air over its lifetime stays as carbon, instead of returning to the atmosphere as CO₂ or methane within years or decades. The appeal is that the hard part of carbon removal — pulling CO₂ out of dilute air — has already been done, for free, by photosynthesis. The engineering problem is narrower: stop the rot. ...