To emphasize, climate change isn't just 'temperature increase'. There are other factors involved that we don't feel directly, so it's ridiculous to brush it off as just another period in a varying climate. 'Global warming' is a misnomer because it doesn't recognize non-warming factors like acidification, increased biodiversity loss/extinction, overconsumption, deforestation, etc all of these things that aren't directly 'warming'.
CO2 levels were below 280ppm for eons, but we've pumped so much additional CO2 into the normal flux, we're almost at 400ppm.
Ignoring everything else, greenhouse gases are great for the environment. They keep us from freezing over or getting hit with some harmful solar radiation. However, when we add too much into the atmosphere, we'll start migrating towards an environment akin to:
VENUS