

The title is, unsurprisingly, heavily exaggerated. The study does not claim there are “billions more people”. They studied 307 different dam construction projects around the word, and found the actual number of affected people in those rural areas was like 40-80% higher than estimated.
Their conclusion is that it’s likely the population of the world is quite underestimated, but they don’t want to guess by how much, that’s all cooked up by the “journalist”.
But that’s the thing, you’re NOT out there with your catapult, so the statistics still hold true. Assuming you were given the catapult and I was given a giant tesla coil, I believe I would still be able to zap 30x more giraffes than you could hit with your pathetic catapult.