The conversation about climate change is going to morph into a conversation about directed geo-engineering over the next 70 years or so. Earth is a semi-closed system of energy and matter flows, and it's not useful to think about it as this static environment that we inhabit. Rather, it's clear that the activities that humans want to perform result in fairly heavy modification of a lot of the geo and biophysical cycles that result in conditions favorable to human civilization. Unbounded inputs (such as our carbon inputs) are inevitably going to lead to unacceptable equilibrium conditions, and so we need to take more direct control of these various geophysical processes.
To me, this seems like a natural extension of our hydrological management projects, and of our reshaping of the biosphere to our liking. Take the continental US as an example - we have totally transformed the ecosystem from primeval forests and plains into this totally human-managed ecosystem of crop lands and domesticated animals. The next step is to think about the entire planetary biosphere, and apply large-scale engineering projects to directly modifying and managing it. Emissions control is a primitive way to do that, but it will eventually have to be more comprehensive and sophisticated. Eventually we need to sequester atmospheric carbon, but we also need to manage things like ocean acidity and the nitrogen cycle - all of these are critical factors in the set of geo/biophysical systems that create planetary conditions favorable for human civilization.
The trick is to develop and deploy these methods fast enough that we can race ahead of climate conditions that become too unfavorable to support a civilization that is capable of deploying them. I think people underestimate how much can be accomplished on that front in a very short amount of time, but that still doesn't excuse the complacency about it. In particular, I'm frustrated by the lack of urgency when it comes to preserving what remains of the "natural world" - at this point, I'm basically writing off a lot of the natural diversity that exists currently, and expect that the current mass extinction event will be the most severe in planetary history. Even if human civilization survives, it will exist in a mostly artificial biosphere with a tremendously streamlined set of species.