Global warming is real because the planet is still coming out of the last ice age.
I think the human impact is exaggerated. All things considered, the planet has survived worse than whatever we can do it, even if we simultaneously detonated every single atomic bomb, and then salted the radioactive remains.
The "Hundreds of years" it takes for plastics to decay is nothing on a geological time scale. Hell, the hundreds of thousands of years for Radioactives to decay is barely a wink in itself. Conservationism is as much a self-serving agenda as industrialism. And while I personally like the idea of preserving natural beauty, I'm under no allusion that it's to "Protect mother Earth". It's cause I think green is pretty.
When most people say "Global Warming" they are referring to the politically motivated AGW theory that stats an increase in atmospheric CO2 levels results in additional water vapor in the atmosphere which results in a further increase in average global temperatures.
The properties of CO2 itself is very well known, it absorbs and remits radiation in a very specific wavelength and is transparent to the rest.
In the 15u range CO2 competes with H2O for it's green house effect, outside of that H2O dominates all other ranges to the tune of 95%+. Those cause's CO2 to experience a logarithmic temperature increase where you need to double each increment to get the same effect. The result is that the bands that CO2 is absorbent on have already been saturated at under 300ppm. Doubling the atmospheric CO2 won't result in a temperate increase as you can't get more energy out then was put in by the sun, and CO2 can only absorb and remit radiation on specific bands, all you get is a lowering of the CO2 ceiling and a
localized increase in temperature (urban heat island effect). This is all well understood physics. In order for CO2 to directly heat the atmosphere anymore then it already is, you'd have to violate thermodynamics and create energy in the atmosphere, or you'd have to have CO2 remit on wavelength's that it's transparent at.
In order for AGW theory to work you need to create an atmospheric forcing effect where higher CO2 density forces more H2O vapor out of the Oceans and into the atmosphere. That additional H2O vapor would then cause an increased global greenhouse effect. This theory got big time traction until one minor discovery was made, that cloud formations in different parts of the atmosphere do different things. Prior to this AGW theorists used a singular total H2O density term for their models, and so
any observed increase in H2O would signal an increase in greenhouse effect. Now we know that cloud formations in the upper atmosphere end up lowering global temperature by reflecting sunlight away from the surface while clouds in the lower atmosphere increase the global temperature by doing the opposite. What we get is a system that auto-corrects, which fits perfectly with the multi-million year history's of global temperature and global CO2 levels. Global CO2 levels have been 3000ppm in our distant past, during the time of the greatest biodiversity our planet has ever experienced. And it would also explain the 17+ years of absolutely no "global warming" aka "global pause" that we've experienced lately, even though CO2 levels keep going up and we've long since past the "point of no return / catastrophic effects".
I'm an environmental conversationalist, I like forests, rivers and wildlife. Hell I probably a better woodsman then all the "green" posters here, having essentially grown up in a giant forest surrounded by mountains. I'm also a pragmatist rather then an idealist and stay away from "crusade" activism. What's pissed me off the most about the AGW movement is the stupid politics diverting funds from environmental conservationism into the coffers of AGW-proponents.
:Note:
There is a very small warming effect that happens between 200 and 400ppm CO2 due to the atmospheric density being lower in the upper atmosphere. It's the result of there being less chance of striking another CO2 molecule above you at low densities. Once you crest ~400ppm you've lowered the CO2 ceiling enough that it no longer matters and, statistically, your reabsorbing all emitted IR in the 15um and 7um range. A small portion will always get out due, but that portion is too small to even be measurable.