That is very true, but the issue really is the speed of change not the total amount of it. If we were to raise 2c over 10,000 years, that would be a non issue for the most part, adaption time would be so slow that many civilisations will come and fall between then. That it is happening over a hundred or so years, that is a huge whip lash and thats where the problem lay. We built a large but somewhat fragil industrial system assuming continued stability. Dumping 2 trillion tons of CO2 into an already barely stable system will not go down as the brightest idea we have had.

If you go from the top of a building to the bottom, it isnt the height that is the issue but the speed of change. You take the lift, not jump of the side of the building.