> and which are harmful?
It is easy to see which ones are harmful. The ones that will cause the sea level to rise a few feet, or eventually 200 feet. The ones that will make the 'corn belt' into desert. The ones that increase tornadoes and cyclones in both ferocity and number. The ones that bring winter snows deeper into the south and more intense in the north*.
> where did you get the idea we know enough about the climate to make rational moves toward controlling it?
It is not about controlling the climate, that cannot be done. It is about controlling human activity so that the situation gets no worse, and potentially can be made better. It has been working for the Ozone Hole, which is healing since CFCs were banned. Now we need to ban fossil fuels so that there is no more carbon dragged out of the ground and poured into the atmosphere. We need to ban deforestation, which also puts 'locked up' carbon into the atmosphere.
Once the increase in carbon is stopped then we can work on how to remove the excess carbon and hope that brings the climate back to as it was a few decades ago.
* 'global warming' is putting more energy into the weather. This not only give record high temperatures, as is obvious, but it also gives more energetic weather patterns, pulling winter weather further south, such as has happened in Louisiana a couple of weeks ago.