answer:Yes, they could. Copper (when near oxygen) eventually makes the chemical copper oxide, which has a greenish color. That, and carbon in the atmosphere, eventually turn into copper carbonate. The copper carbonate actually protects the copper underneath from deterioration. It’s unlikely that anyone will ever polish the Statue. First, because 100 years of tradition knows it as green, Second, that would actually weaken the statue by exposing raw copper, and finally because it would cost a hell of a lot to do.