Germans: Gibbon’s Decline and Fall of the Roman Empire Chapter 9

A big current question is climate change.  This seems very contemporary , so it comes as a bit of a surprise to open the Decline and Fall of the Roman Empire at Chapter 9 and find Gibbon discussing climate change and referring to a series of other writers on the subject.  It seems that quite a few writers back then were proposing that Germany had previously been much colder.