Enhanced rock weathering — spreading crushed silicate rocks on agricultural soil — removes carbon dioxide from the atmosphere through the same chemical process that naturally weathers mountains over geological time. Silicate minerals react with CO2 dissolved in rainwater, converting atmospheric carbon into bicarbonate that washes into the ocean and is stored as carbonate on the seafloor. Crushing the rock increases the surface area, accelerating the reaction from geological to agricultural timescales. The co-benefits include soil nutrient delivery, improved crop yields, and reduced soil acidity.
A Cornell-led modeling study, published in Communications Sustainability, projected global adoption trajectories for enhanced rock weathering through 2100. The key finding: by 2050, warmer and wetter Global South countries — India, Brazil, Indonesia — overtake high-income countries in adoption and carbon removal. This is not because of policy or economics. It is because of chemistry. Silicate weathering kinetics are strongly temperature-dependent. The same crushed basalt deployed on tropical soil reacts faster than on temperate soil because the reaction rate increases with temperature and water availability. The Global South has a thermodynamic advantage.
The projected removal: 0.35-0.76 gigatons of carbon by 2050, rising to 0.7-1.1 gigatons by 2100. These are significant but not transformative — roughly 1-2% of current annual emissions. The significance is in the distribution, not the total. The countries that benefit most from the co-benefits (nutrient-poor tropical soils) are also the countries where the chemistry works fastest. For once, a climate intervention's effectiveness is aligned with, rather than opposed to, the geography of need.
The structural insight is about geographic matching. Most climate interventions — carbon capture, nuclear power, renewable energy deployment — work best in wealthy countries with technical infrastructure and capital. Enhanced rock weathering works best in warm, wet countries with extensive agriculture. The intervention's optimal deployment zone overlaps with the countries that are most vulnerable to climate change and least responsible for causing it. The chemistry doesn't require a factory or a power grid. It requires rain and warmth.