However, in later years, as the bar to a new record increases, the numbers of records become much smaller, and so the ratio fluctuates much more. The upshot is that by using the running records method, the ratio graph is guaranteed to show a long period of values around 1 at the start of the record, followed by dramatic variations toward the end, creating the impression of large changes in recent decades, even if they aren’t present. While it produces a scary visual, this ratio has almost nothing to do with how temperatures are actually changing.
