> the lower and upper bounds, given current technology, are 0.65 billion and 98 billion people, respectively.
The answer is "anywhere from a tenth of the people currently alive to 13.5 times as many as are currently alive." Absolutely useless. A range covering more than two orders of magnitude. May as well say, "We don't know."
Not at all. To say "we don't know" might mean that we don't know the order of magnitude. Order of magnitude estimates to the first or second decimal place are oftentimes more than enough to hone in on a solution. In this case the two orders of magnitude set a clear bound (assuming the capacity estimate are accurate) for the near future at the high end and provide a warning sign for the present.
This is a meta-analysis. They reference many different papers. Many of them come to different conclusions. If you want more certainty you can get it by starting to read the papers the reference and deciding which ones you think are reasonable.
The answer is "anywhere from a tenth of the people currently alive to 13.5 times as many as are currently alive." Absolutely useless. A range covering more than two orders of magnitude. May as well say, "We don't know."