The earth will be here no matter what we do. The difference will be what species exist on it, and the argument isn't that we are leading ourselves to an apocalyptic destruction, but that we are trending in a direction that could have dire consequences for a decent chunk of the population both human and otherwise. Frankly, I wish scientists would stop trying to predict what will happen so they don't have egg all over their face when it doesn't.
What we do know is that the earth is warming significantly faster than in other periods of its history, and that greenhouse gases are a major player in the process. If you want to ignore that it is certainly your prerogative, but I'd rather play it safe than assume nothing horrible is going to happen. If nothing else we can be assured that the earth is losing a large portion of its fresh water supply as the glaciers melt. Supplying fresh, clean, water to our population is already becoming an issue and we're losing significant portions of the earths reserves.