Olivine (magnesium iron silicate) is an ultrabasic mineral which makes up the majority of the earth's mantle and can absorb its weight in CO2 if it's cooler than the ~350C at which magnesium carbonate decomposes but warm enough for the reaction to proceed quickly.

Resolves YES if human intervention increases olivine-based direct air capture of CO2 by >10^9 tons/year before 2050 (~3% of anthorpogenic CO2 emissions in 2022)