Can We Actually Even Tell if Humans Are Affecting the Climate?

PJ Lifestyle » Can We Actually Even Tell if Humans Are Affecting the Climate?:
"We know, with great certainty, that the overall average temperature of the Earth has warmed by several degreees in the last 400 years, since the end of the Little Ice Age.
Before that was a period called the Medieval Warm Period; before that was another cold period; and back at the time of the Romans there was a long period that was significantly warmer — Southern Britain was a wine-growing region.
What we’re a lot less certain about is “why?”