It is not a photo, it is not a closed room. We are in a system, that have inputs and outputs. With more than GHG (not just CO2) than preindustrial times, the pl

It is not a photo, it is not a closed room. We are in a system, that have inputs and outputs. With more than GHG (not just CO2) than preindustrial times, the planet keeps more energy of what it receives to the sun. That affects the pretty complex system that is the climate one, in several ways, and triggering several positive feedback loops that makes things even worse (i.e. losing ice over ocean means less albedo, and more energy capture, whatever is the concentration of CO2 in the atmosphere). And some of those feedback loops even do their own emissions of GHG, like more methane from wetlands, and the one emitted by permafrost thawing, potentially more water vapor that is a strong GHG, and so on. There is a point where the concentration of CO2 is directly harmful for human beings, 450ppm is still far from that. But having too much for too much time put the system on a roll into a direction that we don't want. And we are not decreasing it, but still accelerating the rate at which we emit it.