The resulting carbon, called biochar, can be co-composted to prepare it for use in soil, where it protects the soil from drought and flood alike. Plants grown in soil with higher carbon content are bigger and healthier, and these soils can produce more of whatever you're growing.
I make biochar at home but there are companies that do it on an industrial scale.
Humanity has been pumping CO2 into the atmosphere at an epic scale for decades. In addition to going carbon neutral with more wind, solar and nuclear, we need to draw CO2 back out of the atmosphere on an epic scale. And biochar resulting from pyrolysis is one of the major tools since it has synergistic effects with other tools, like mass tree plantings. Biochar production can also offset other energy uses, for example by either directly burning the syngas on-site for heating purposes, or for capturing it and using it later as a fuel in an application that would otherwise use fossil fuel.
Either way, I completely agree. Planting trees doesn't solve the problem if those trees are allowed to naturally decompose. Trees are just really efficient carbon fixing machinery, we need to store the solid carbon somewhere.
I imagine a solution where people grow stands of fast growing trees, clear cut every $optimal years, use (magic?) chemistry to separate the harvest into carbon and not carbon, then dump the not carbon back onto the soil, and replant.
Even with that, I’m not convinced there are enough acres of land on earth. I haven’t seen anyone do the math, and suspect direct carbon capture plants and olivine reactions will scale better.