I suppose you mean this to be about the ArC
Is it a good idea? On the surface it sounds dandy, deeper down it would likely just postpone the inevitable, since, this earth has a regular habit of regulating itself. If it isn't done now, when?
I am more concerned about people taking measures to strengthen what is already here. Stop using so much plastic, abandon the comfort of polar fleece (a manmade material which has been shown to end up in the water system and inside fish), recycle, walk or bring others with you when driving to the stores. So many ways we've destroyed the planet and now we decide we want more time. Such arrogance and stupidity should not be condoned. Either we fix it the natural way or we go the way of the dinosaurs.