It is an open, but not unanswerable, question as to how much carbon from atmospheric carbon dioxide and methane is sequestered as biochar by vegetation fires. In this work I conceptualise the question as an important aspect of the global Charcoal Challenge, which deals with the scientific and socioeconomic questions associated with increasing the refractory biochar pool at the expense of the atmospheric carbon pool. I discuss a mechanism by which thermoconversion of biomass may act as a regulator of the global distribution of carbon between these reservoirs, show how suppression of vegetation fires by human activities may increase the fraction of carbon in the atmospheric pool, and elucidate three specific issues which are given the designation CharΧive Challenges.