Guess what... we weren’t there “destroying the ozone layer” at that point...which means human beings have nothing whatsoever to do with “global warming,” if it does in fact exist.
The earth has warmed and cooled several times over its many millenia. Mediaeval Europe suffered through a horrible cold period that we cannot even imagine and human beings had nothing to do with it.
Despite hysterical warnings that an increase in temperature is caused by industrialization and will be unambiguously harmful to the economy - the Medieval warm period was pre-industrialization was was, by all accounts, a rather good thing. The “little Ice Age” that followed wasn't as much fun.