Back in 1856 Eunice Newton Foote, created an experiment showing CO2 traps heat from sunlight, by putting jars containing varying degrees of CO2 in direct sunlight.
What she wrote in her paper describing that experiment was the heat rise happing in the jars fill with CO2 could also happen to our planet.
“An atmosphere of that gas,” she noted, “would give to our earth a high temperature”.
So, the science describing this phenomenon is nothing new. When it comes to the science, there is no longer any doubt.
Nothing in science is proven without any doubt. Check the meaning of the words theory and hypothesis.
"Isn't it possible that global warming is part of a naturally occurring cycle that happened by accident at the same time industrialization took place?" - You can ask the same type of question about literally everything we can observe and every theory explaining that. Isn't it possible that things falling down is just random phenomena and not a proof of some gravitational theory?
If you have a good alternate theory to global warming then explain/link to it.
