Substition refers to a fact that many people do not believe.
Substition was coined by the British novelist Terry Pratchett, who died on March 12, 2015 from Alzheimer's disease. It's the opposite of superstition. That is, a superstition is something that isn't real, but many people believe, so a substition is something that is real, but many people do not believe.
Climate change is a substition. For most of human history, bacteria and viruses weren't believed to be real even though people died of them. Bacteria were a substition. Just because you don't believe in infectious diseases doesn't make them any less real.