Steel uses so much carbon that it’s been a target for using hydrogen as a reducing agent. There are a couple ironworks that have already started converting.
That’ll still leave concrete as one of the next largest sources, even if the rebar gets a smaller footprint.
That would be true if there had been zero effort and money spent in subsidizing fossil fuels, hiding data about its true long term impact for decades and sabotaging efforts to move away from carbon dependence.
That’ll still leave concrete as one of the next largest sources, even if the rebar gets a smaller footprint.