We like to have backups for systems that we have some expectation of failing. We have RAID drives for our data, fire insurance for our houses.
Things that we consider highly unlikely, we ignore. Suppose, for instance, that all air travel in Europe were to be shut down for an extended time. Well, surely we'd travel by rail and by boat.
Well, it turns out that it hasn't been cost effective to maintain enough boats to handle the overflow from shut-down airports. We expect air travel to be continuous. A sudden and unexpected failure of air traffic turns out to be a real blow to the system because insufficient backups are in place.
We don't know these brittlenesses until they are unexpectedly exposed. A few years ago the Chicago River found its way into the basements of many buildings in the Loop, a risk nobody had ever considered.
I would even consider ClimateGate a brittleness. The explosion of totally unfounded accusations had a significant impact because of vulnerabilities in the press as well as within scientific institutions. The main consequences of this particular weird failure remain in the future and may yet be avoided, but the risk that a thousand generations will suffer as a consequence of some easliy misinterpreted grumbling about trash science remains real.
What can we learn from finding ourselves in a science fiction world, where we are plagued by failure modes we never even imagined? It seems to me that we are living closer to the edge than we imagined. As complexity increases, the potential for disastrous coupling between systems that aren't conceptually linked (Icelandic vulcanism, German automobile production; coal delivery in 1906 and bridge repair in 1992) increases. How many other things will butt up against other things their users never considered?
This is what makes climate change special. To be honest, we don't know what will go awry when and how much and how under anticipated climate change. But climate butts up against almost everything pretty much everywhere. Building practices that have never been exposed to termites will see termites. Rivers that have never had flash floods will get flash floods. Countries that have never seen hurricanes will get hurricanes. Who knows what all else will happen?
As the T-shirt says, there is no Planet B. If air traffic shuts down forever, we'll get boats quickly and fast boats before you know it. But we have no backup plan for the atmosphere.