> Think we're dumping too much CO2 into the atmosphere? We no doubt are but that problem basically goes away immediately if we ever get economic fusion power.
That's an enormous "if". Fusion research has been underfunded for decades, we don't even know if we can sustain it, and for a reason I don't get, many ecologists are anti-nuclear. Plus fusion won't solve everything. You won't put a sun core into your car nor your plane, not in the next centuries.
> Even if we don't, the plummetting cost of wind and solar may solve that anyway (by "solve" I mean that as soon as non-fossil fuel power production is cheaper than fossil fuels it becomes economic to remove CO2 from the atmosphere and turn into hydrocarbons).
Oh, you mean the unreliable power sources that sometimes provide electricity, sometimes don't?
> The Earth has also been a lot warmer than it is now
Well yes but 5°C is also the difference between an ice age and a hot age. We're currently in a hot age and the 4°C increase we're heading to are not very engaging. (Remainder, during ice age North America down to NY and Northern Europe down to Paris were covered by enormous glaciers. So what will the climate be in 4°C?). https://xkcd.com/1379/
Also in human history the Earth has never been this hot.
> Too expensive to get to space? Eventually the cost of this will go down to dollars per kilogram.
Ha. To escape Earth gravity you still need to spend 6.2*10^7 J/kg. That's gonna be a long time before we get to 1$/kg given that rocket propulsion is extremely costly (and as far as we know can't rely on atomic energy either). We're still at ~25 000 $/kg. And anyway recent studies show that the human body is unlikely to bear a trip to Mars, let alone the health issues caused by weightless environment.
Edit, source: http://www.pnas.org/content/early/2018/09/26/1807522115. Basically the study suggests heavy ion irradiation is dangerous for the digestive system. The only thing is I'm not sure about the number of mice they used.
> We also seem to have a pretty poor history of predictions when it comes to climate change too.
I mean it's not as if oil companies conducted their own research and reached the very same conclusion in 1977. Oh wait. https://www.scientificamerican.com/article/exxon-knew-about-...
I'm sorry but you're just burying your head in the sand, making the problem someone else's.