Last you BOTHERED to read about.
What's the temperature the earth should be if there was no GHG? about 50 degrees cooler (I think, but if you can't check either, we'll go with that).
2%of that is 1 degree. Again, I believe this is low, but if you contest 50deg, check the 2%, yeah.
And our fuel consumption is increasing while the ability of the system to absorb CO2 is erducing (plants need water, CO2, nirtogen, potassium, etc, so increasing CO2 without increasing the rest isn't going to help much).
And, since this is an artificial increase, there's no going down, so it will be 2 degrees.
But how much bigger will the desserts become at that? How much smaller the ice caps? How much more wind energy will be there, how much more rain (and how many more hurricanes)?
Oh, and higher temps, more water vapour (higher water vapour pressure possible) and the more water contributes, which means more water....
We have produced more than half the changes in temperatures. This is worked out because models that predict past weather from a starting point in the further past progress to a climatology that does mirror what the records say. A lot of frigs and so on, but if they work when taking a 150-year old weather report and running the model for the next 50 years THEN checking against the records for those 50 years works, there's no real need to change the frig factors for the last 50 year's climate when taking the 50-year-old weather report and running those exact same models.
Now when the last 50 years only match when you add in the human created factors and cannot by any means be made to fit without them, you know that the human factors are needed.
So we are only able to explain what HAPPENED when we include what we did.
To deny that is to deny science any ability to predict. We can't SEE atoms, we don't KNOW what elecrons are, nor why they seem to occupy "shells". We have mathematical models with fiddled constants that produce the right answers, though. And with those models, we predicted how to make lasers. How to make red LED lasers and how to create blue ones (so now we have white LEDs).
Not because we KNOW what an electron does in a semiconductor but that our best model description seems to work in helping us predict what to change to get the answer we're looking for.