To paraphrase: "silicate weathering works too well in the lab compared to in nature, making it difficult to figure out how quickly natural chemical weathering is absorbing CO2".

Now me, I'm generally all about the lab science, but in this case I'm thinking maybe we need to move outdoors and spray a few acres somewhere warm with a lot of annual precipitation and do some empirical measuring.  A year in the field could save a decade in the lab.