Carbon uptake during weathering
Over geological time, the weathering of silicate minerals on land to form limestone in the ocean is a natural climate stabilisation mechanism, because it is the Earth's dominant natural mechanism of removing atmospheric CO2. Weathering is thought to operate on time-scales of greater than 10,000 years. We are investigating the potential of speeding this up, and thereby enhancing CO2 sequestration by spreading crushed silicates onto the land surface. Weathering is enhanced in two ways:
1) the surface area of the material is substantially enlarged by crushing and grinding which means that there is more material exposed to the environment.
2) Biological activity in soils naturally speeds up weathering as a way of extracting nutrients from minerals.
Because there is large uncertainty in both of these areas, the feasibility of enhanced weathering is poorly understood. Furthermore, the effect of enhanced weathering on the Earth's natural chemical balance is not well understood. We are combining studies of enhanced weathering with studies of natural processes.