Arrhenius stated only that CO2 acted to absorb heat (long-wave infra-red radiation for the nitpickers). He posited that if you added CO2 to the atmosphere the heat would increase. What Arrhenius didn't know, or didn't fully grasp, is that at 280ppm, the atmospheric CO2 already absorbs 97% of all incoming long-wave infra-red radiation. Doubling the CO2 to 560ppm, would not make it absorb 194% of the radiation, it would make it absorb about 99% of the incoming radiation. Since CO2 accounts for approximately 4-7 degrees C of the Earth's warming (there's arguments on the exact figure) that would be an increase of about 0.08 to 0.14 degrees C. Now, there are some factors that add to that (re-radiation, tropospheric concentration and re-reflection of albedo infra-red, etc) that could make that as much as 1 degree C of surface warming. But that's it.
Adding twice the CO2 doesn't mean twice the temperature. And the feedback mechanisms are neutral to negative. They must be, or the 7000ppm CO2 of the carboniferous period would have resulted in Earth looking like a ball of molten rock.
Now, let's get back to the real point.
Climate scientists continue to make statements like, "We can expect more Katrina's every year!" Yet the U.S. is now in its longest cycle without a major hurricane landing since records began being kept in the 1930's. "We can expect more tornados to ravage cities across the U.S.!", yet tornadic activity across the U.S. is at a 50 year low. Total thunderstorms are average at best, and while there is some evidence of slightly stronger convection cells, there's a certain bias in the fact that we never before had satellites capable of sampling and quantifying such activity in seconds rather than days.
In short, the evidence all points the other way.
Now, don't get me wrong, I'm no shill for gas or oil or coal. I'd rather see all of it go away. Give me clean, safe, cheap, plentiful nuclear power every day of the week over all of that. Preferably LFTR designs spread out like candy all over the country. I'd love fusion too, but like my Grandfather who was promised to see it "within his lifetime" and died in 1988, I'm not holding my breath on that one.
Solar power is a joke, with its rare earths and sulfur-hexafluoride washes doing a dozen times more damage to the environment then they'll ever recover in a lifetime. We've already tapped 95% or more of the hydropower on Earth, and I doubt the birds will live through putting up enough windmills to power a typical city, much less the planet. Not to mention, that has it's own problems. Wind Power Potential Overestimated
Your point, "We've seen warming" ignores the one great thing about climate change -- the climate is a complex system -- it is always
changing. It is a vast, living, breathing system taking in all life on earth, all changes in the sun, all chemistry in the oceans, every wave, every sunbeam, every butterfly flapping its wings. It must be constantly changing. We are looking at a tiny sliver of it and saying, "Oh no, we're all doomed!" We act as if we want the climate never to change, not one iota, not one jot.
The climate never changes on Venus, on Mercury, on Mars... They all have one thing in common. They're dead worlds.
Give me a changing climate any day over that.