Aeneas, you are almost right about one thing-we have some small influence on two factors. Insignificant would be the correct term. Now if we could figure out how to prevent volcanic erruptions, we might could help out old Mother Earth a little more.
Seeweed, what do you want to do next, ban oxygen?
"Insignificant" is pretty far from the truth. The energy input from the sun is why the temperature is typically around 290K instead of absolute zero. Our CO2 output from oil use alone accounts for a tiny fraction of the total amount of CO2 in the atmosphere, but that's enough to shift global temperatures by a couple of degrees.
Yes, I'm aware that water is also an important greenhouse gas, but saying it makes the CO2 irrelevant is like saying it's useless to roll down your car windows on a summer day because the roof is holding in more heat.