One can prove to oneself that there is prima facie good reason...

One can prove to oneself that there is prima facie good reason to think that increased carbon in the atmosphere causes increases in temperature. Take a fish tank affix a thermometer inside, seal it and pump in CO2. The temperature will rise.

It has been known for at least two hundred years that increased concentrations of carbon in the atmosphere has the same effect (trapping heat and so increasing temperature)...

All this doesn't entail that human induced climate warming is a real phenomenon. But it gives one good reason to think that it is not as outlandish as some are wont to portray.