You are spot on.
The truth is that just like other scientific research and studies most are just educated guesses.The earth has always undergone periods of climatic change throughout history,swinging towards iceage and to periods of warming.
This climate change usually lasts about 40,000 years.
The sun also goes through major cycles of overheating and cooling due to increased solar flare activity etc which has more effect on the earth than a bit of co2 ever will.
Carbon dioxide accounts for less than ten percent of the greenhouse effect, as carbon dioxide's ability to absorb heat is quite limited.
Only about 0.03 percent of the Earth's atmosphere consists of carbon dioxide (nitrogen, oxygen, and argon constitute about 78 percent, 20 percent, and 0.93 percent of the atmosphere, respectively.