EAGLEDNY: I'll plonk a little text for you since you provoke questions to be answered.
Quadruple the co2 from one source (as an old static, every day we burn CO2 that it takes the globe some 2500 years to tie down, but I belive the authency of that can be doubted), - Anyway, quadruple the co2 in th atmosphere in some mere 200' years, and it's MASSIVE an impact on any scale. At the same time, mankind is doing it's best of nilling down the countering effect you happen to mention:
"Also - quadruple CO2 in the presence of plants that take in sunlight and CO2 to make oxygen and you will get a correcting factor in the environment to take the CO2 levels back down."
It would be if we weren't chopping down the correcting factor. Of course guys like Jacka1 would correct you there by telling you in a most informed manner thet plants create greenhouse gasses.
In this particular timeframe, nothing else explains it as well. So, enter sapiens with a punch, except may of the species don't live up to the burden of carrying the "sapiens". In one line:
"WE, H.S. Species, definately changed the atmosphere"
As for water vapour, the permafrost, the poles (icecaps), you seem to be a little bit on the tracks and yet not.
What now is the permafrost used to be a bog. And god knows what before that. At the same time you had cold areas elsewhere. The poles have shifted, the planet does that. Where I live near the Arctic, there was a clster of Islands with tropical temperature, millions of years ago. Only 100.000 years ago it was swamped under thick glacier. I look at hills which unveil sea polished cliffs some hundreds of feet high. I dig down only 12 feet to find an old seashore bed. So, you aren't telling a big headline statement when it goes to our terra firma going through changes.
The scaryest "doomsday" part of swift global warming, is that with our load on the scale, we will enable such a swift warming that we will experience a unique timeframe of minimal caps, permafrost and forest with the maximum amount of greenhouse gasses, - first comes CO2, then the permafrost releases the Methane, which makes our business day around the world look like a pinsalamander in comparison, - everything warmes, untill the formentioned 70% blue mass of the planets surface starts hitting stunning figures (that means gulf of Mexico temps in the Arctic, and near Florida, oops), - we get anything between bad and worse, - bad being hundreds or thousands of years of mad climates, worse is the accelerating boiling point, the vicious circle where our water will enclose our globe with a greenhouse effect strong enough to make a Venus atmosphere.
The globe has seen some highline stuff, but with us at the accelerator there may be a new record in sight. So factors are CO2, Methane, forests, and pollution as human affected, rest is not up to us. It's about navigating the roller coaster not propelling it.
Then on to merry old Lazs. Always full of wisdom. Okay:
"ITS THE SUN STUPID..
The sun is warming up the planet... as humans.. we may have some small effect in speeding the warming that, as of yet, can't be measured. In any case... it is minute compared to the suns effects and.... no matter what we do..."
FYI, (May I call you more stupid), without greenhouse effect, the globe would be a snowball. It works that way. With enough effect, Mars would be cosy, and with less, Venus might too. The error margin from snowball to BBQ is actually quite ... minute. Same goes with the sun, and the earth's orbital distance etc. But we can only do what we can do and in your surrender park that sounds like:
"WE CAN'T CHANGE ANYTHING."
And that's where you're absolutely wrong. We have already massively changed the terrain of the planet, and it's atmosphere. The changes that are human related in the last 200 years or so, are more than something like the rest we did from the beginning of mankind. but unlike that, what was happening 7000 years ago (okay, only 6000 years) could carry on with relatively little impact, while what we do now (the things that are easy and cheap) will never work as a whole on something as short as a 1000 years, even much much less.
So, we will be forced, one way or another to change our style.
And finally, John:
"angus is afraid his igloo is going to melt."
Maybe your tipi is going to go crusty and fall down? In my country we never lived in Igloos FYI. And we used the skins for writing books on, a thousand years ago.
(There are descriptions of landscapes and climates BTW)