The so called science you are referring to was in a sense settled in late 19th century when the first greenhouses were built.
I assume you must be referring to the work of Tyndall in 1859 on the thermal properties of atmospheric gases.
It is very likely that an increase in CO2 will cause a rise in planetary temperatures (global warming)
Thermodynamics dictates that it must, and the no-feedback forcing can be more-or-less directly calculated. The standard figure for a doubling of CO2 is 3.7 W/m^2, which is considered equivalent to ~1 degree global temperature rise. Beyond that, as you say, there is a bit more uncertainty.
Also we cannot be 100% sure that the 100ppm rise in CO2 in the past century was caused by human activity.
Actually we can. We've measured volcanic outgassings all over the globe, and we know from the C14 ratios that this is very old carbon. Additionally, oil is the most traded commodity and we're pretty clear on what is being burned where, and how much. That level of trade leaves quite a paper trail.
So far, in the past 100 years, the 100ppm change has clearly not been catastrophic.
Catastrophe is exactly the term that comes to mind about the Arctic. I'm from Alaska, and the changes up there are jaw-dropping. All of the glaciers are in rapid retreat, especially the lower alpine and tidewater glaciers (the more visible and accessible ones). One glacier near my house lost twenty cubic miles of ice in ten years. Not square miles, cubic miles. Now of that certain facts must be mentioned. That particular glacier is not suspected of melting due to climate change, but that is the scale of the changes. It was shocking to see all of that go all at once, but literally everywhere you look there is less ice year by year. Alaska has lost 75 billion tons of ice every year for the last 30 years, as compared with about ~3.5 billion tons of oil burned annually during that period. Now, that may not be a catastrophe to you, but the real bad news is that we're only getting started: the warming signal from the CO2 rise has only been considered clearly detectable since the 90s.
Humans aren't good at predicting the future. I am not smart enough for it. I am definitely not better at predicting things than thousands of scientists working together around the world. You're suggesting that we know nothing about the future and couldn't possibly guess what might happen tomorrow by using physics. In point of fact, you have no idea what is known or how good of a guess we might have. Yes, there is uncertainty in this as in all other empirical fields, but there are very little physical grounds to speculate about non-catastrophic scenarios. As I mentioned in another post here, our current rate of CO2 production is equivalent to one or more Yellowstone-sized supervolcano eruptions per year (source: Gerlach 2011). What does that suggest to you about what's going to happen?
So firstly, any argument against science needs to be made in the language of science, and on this subject you don't know enough to participate. Neither do I -- neither of us has earned a doctorate in a related field. But more fundamentally you don't understand what science is. That the science could be wrong is not a possibility, but a fact: science is empirical, and cannot avoid experimental or measurement error. However, within those constraints, scientific truths represent repeatable observations about how the world works, and any further theories will need to describe the exact same behavior. If science says that an apple falls to Earth, that will be true forever no matter what. If the science says that the Earth is warming due to carbon from anthropogenic sources, then there is not going to be another theory that comes along that says something different. And while I respect your right to an opinion, in this specific case I will say that if you can argue with the science, you haven't understood it, and in your place I would be ashamed to speak about any subject where I had so little knowledge.
I sympathize with you; I also do not want this to be true. It's a complete shit sandwich, and the political consequences are also generally pretty crap. I'm not pushing for any particular action on this for a number of reasons. Mostly I trust that you and the rest of our fellow citizens can make good decisions when you have accurate information. However, before you do that, you're going to have to give up your own ego, and your motivated reasoning, and face the actual facts. Reason is a powerful tool, but you don't get to reason away empirical observations when you don't like them. There's not any perspectives here, or any partisanship. Thermometers don't have political motivations. If you have a problem with this science you have a problem with objective reality. (Which frankly isn't everyone's cup of tea and I'd at least consider it intellectually honest for you to take that position.) My advice is not to argue with reality, and correspondingly it's not a good idea to argue with scientists unless you are one.
To further your education, I would recommend starting here for a good overview of the science from a historical perspective, taking note of the various discoveries that were made. Most of the papers it references are available freely online, and in particular I'll note that the papers published before 1950 are a small enough crowd that you can pretty much read all of them in an afternoon or two. Google Scholar will be useful, but you may have to go to a university library to get access to the journals. If you'd rather do your own investigation, you might review Tyndall 1859, Arrhenius 1896, Callendar 1949, Keeling 1960, Hansen 1988, and of course the IPCC reports for anything more recent. I will freely admit however that I have not one iota of belief that you have the intellectual integrity to actually do any of this.