So, the point in time that I was trying to point to was not just when some science had been done, but when the amount of research into the area was so overwhelming, and so widely available, that any lay person who even just casually reads reliable news sources cannot possibly not be familiar with it. The point at which there is no longer any excuse for not knowing about and accepting the science, beyond wilful ignorance. A deliberately vague concept that can't be pinned down to one specific date, but that has, as its absolute upper bound the Kyoto Protocol, which was first signed over two decades, but not quite three, ago.