scott_sanford

According to this article human energy use over time plots very close to linearly on a logarithmic scale (~10x per century), back to 1650. Extrapolating, we become a Kardashev Type I in only 400 years - much less than I'd guess, but not impossible with SPS arrays. Past that we hit Type II only a thousand years later, and that seems rather soon for a full Dyson Swarm.

While many functions that look logarithmic eventually go sigmoid, it's unclear where the inflection point is - except that we haven't gotten there yet, and it may be quite a ways out. Much like Moore's Law; we know it tops out somewhere... I'll take a stand that it will inflect well before reaching Type II, and that we definitely won't reach Type III on schedule; if nothing else this would require massive FTL travel, which looks unlikely.

The article also points out that if we're using this amount of energy on Earth, the waste heat is going to become first a nuisance and then a damn problem, as the planet cannot radiate that much energy into space without active assistance. (I expect the author will get some flames because only atmospheric CO2 levels are supposed to be mentioned in this context.) It's not clear how much heat we could lose by, for example, a low-orbit radiator disk and orbital towers - but even trying wouldn't be cheap.

PS: Because I know my readers are the kind of people to be curious, humanity currently uses about 22 terawatts per year, about 0.16% of Earth's total energy budget, putting us around 0.72 on Carl Sagan's revised Kardashev scale.