[tptacek]

Yes, Black is. It's overloaded, but in America, it refers unambiguously to the new ethnicity created by the Trans-Atlantic Slave Trade --- where before you (and, more importantly, your children) were (say) Yoruba, now you were a Black slave. Black people have a numerous and specific shared cultural attributes: language dialects, food, music, religious affiliations. The same isn't true of the varying European ethnicities! Most of what an Irish person and a Slav have in common, an Irish person and a Black person also have in common.

To keep the ambiguity at bay, do what John McWhorter (himself no woke-scold) suggests, and capitalize Black when referring to the African Diasporic people of America, and lowercase it when referring generically to people of African origin, the same way you lowercase "white".