Fifth Force TPB

Earth is on the verge of extinction. We have limited crude oil and our primary fuel sources are negligible. The carbon clouds signal the end of our species. We have but a few options: leave the planet... or fix it.  We are the TFA, a special Canada-based agency that stumbled across a revolutionary discovery. The fifth Elemental force. Time. We built a time machine based on the new physical sciences, believing we can go back to the "inflection points" of this extinction level event and fix things. The irony here is that the fuel we need to operate the invention, is the very fuel that led us to this juncture.