Space.
The world will end some day, and we need to be off this planet when that happens.
I feel you're getting ahead of our capabilities by thousands of years, if not tens of thousands.
That may be the case, but it is something we absolutely must consider WAY before the time it is needed. We have a history, as a species, of waiting until the problem rears it's ugly head before we do anything about it. We won't last more than one or two apocalyptic events if we remain that headstrong and that oblivious to the needs of the future.
I cannot fathom the number of people who quip "if it won't happen in my lifetime, why the fuck should I care?"... which makes me wonder just how much longer we can actually last - as an advanced species - if we don't even think about the upcoming generations, let alone hundreds of years (or more) into the future.
We can't simply have the wait and see attitude, and we surely cannot continue to push off future issues and leave them for future generations to consider (and feel). Hell, our governments typically fail to earnestly plan a few decades out, nor construct anything (of a political nature - services, programs, policies, departments, budgets) that stands up firmly for more than a few decades... even when there is ample knowledge that more must be considered to stave off problems that future generations will absolutely have to patch up.
It's why I honestly don't have much hope for us. Yeah it's great to think about us as a space-faring species with advanced technologies, but I honestly don't see much good coming out of all that for us, because, at best, it'll be like a large slum here on the ground and such vehicles will probably be grounded (if ever constructed).
That's one reason I am actually quite ecstatic the government gave space exploration to private corporations instead of keeping it as a government-controlled entity. We fail to dedicate the budget necessary, and fail to see what can and should be done NOW, to ensure something can come of it when it is practical. Private entities competing with each other, and competing for our moneys, will result in a faster pace for technology progress. Which is absolutely needed for increasing our knowledge for advanced physics, which is fundamental to further our technology and sciences so that we can begin envisioning just how to accomplish our space-faring goals beyond our solar system. Short of massive and unimaginably expensive projects like generation ships (far too early to even fathom at this point, our propulsion technology is not ready for even that just yet), we need far more scientific knowledge. We can't do that without planning and attempting whatever we can do NOW, because, short of stumbling upon chance discoveries (most beneficial advances have actually been born of such), we can't expect the evolution of physics and technology to occur anytime soon ... and it certainly can't happen without dedicating time and resources to the cause.
there is oil in the sea
is there oil in space?
We can strip mine those gas giants (and their rocky moons) for all the hydrocarbons we could ever desire.

Might not be the same stuff as oil, but considering there are far more hydrocarbons in space than we could imagine using in the next few thousand years (and I'm just looking at our immediate solar neighborhood), it wouldn't be a bad idea to switch to those for energy consumption, if we absolutely must.