"I have my opinions" has good ideas, as well as opinions. I assume that this is for a science fair. As a long-time judge, let me offer a few tips. Most important, if only a small thing, never say you are attempting to "prove" something, except in logic or math. You can DISprove a theory or hypothesis but you can never prove one. Also, keep your project simple. Don't start a vast project with half-vast ideas. One of the best projects I ever judged involved mealworms, microscope slides, and a variety of substrates. It measured the preference for rough vs smooth substrates. The project took best in fair.

Suggestion: read up on "albedo" and see whether that suggests something to you; or make a long box with a heating element at one end and a cooling element at the other and see what temperatures are preferred by some animal or other.

It will be hard to prove it is real especially since this theory is mostly based on statistics. Here are something that come in my head that i have not tried before that can maybe work. Take two identical ice cubes and put them in a bottle or jar or cylinder. Next in one of them put carbon dioxide and other one put oxygen and make sure you close them so there is no leaks. Next make sure they are in similar settings, temperature, light, etc. If global warming is correct, the CO2 one should melt first. You can try this with different gases as well such as nitrogen (the most abundant we have), methane, etc.

If you want to do a theoretical/statistical project, do a timeline of the average (high) temperature of the months along with the different events that happen in that time (volcano erupts, industrial revolution, BP Gas leak and fire, etc.) and that can also help you prove global warming in the sense that pollution is the cause seen on the pattern of the graph that you provide.

You could do this one, but you will get the WRONG result just like this kid did. He used heat lamps that output infrared so no wonder he got the wrong results. Much of the Sun's output is short-wave radiation which the heat lamps do not provided. Thus, wrong results.