You're absolutely right and it's a shame people don't get that real world situations are nuanced and immediate needs matter.

Relevant funny Wikipedia excerpt:

"When campaigning for a second term in office, U.S. President Richard Nixon announced that the rate of increase of inflation was decreasing, which has been noted as "the first time a sitting president used the third derivative to advance his case for reelection."[2] Since inflation is itself a derivative—the rate at which the purchasing power of money decreases—then the rate of increase of inflation is the derivative of inflation, opposite in sign to the second time derivative of the purchasing power of money. Stating that a function is decreasing is equivalent to stating that its derivative is negative, so Nixon's statement is that the second derivative of inflation is negative, and so the third derivative of purchasing power is positive.

Nixon's statement allowed for the rate of inflation to increase, however, so his statement was not as indicative of stable prices as it sounds."

https://en.m.wikipedia.org/wiki/Third_derivative

I'm disappointed both with journalists and with redditors' confidently wrong calculus knowledge this morning.

You have it off when you're bringing acceleration into this.

That would be the rate of change of the rate of change of population. Aka the rate at which the growth rate itself changes.

This article, beyond the bungled headline, says population will peak at 8.6 billion people.

When the amount of people stops rising and begins falling, at that moment, the growth rate is zero. The headline is totally screwed up and conflicts with the article.

There's no point anywhere here where a second derivative (acceleration) is brought in.

EDIT: Really, downvotes? You guys aren't even gonna try to tell me my math is wrong?

But the article is saying the population will max out at 8.6 billion. The headline was written wrong, as the article clearly goes on to say that our population will peak at 8.6 billion.

When you reach the peak of the amount of something over time, at that moment your growth rate is zero. That is not only common sense but also basic calculus.

Sure, why didn't the Soviets say anything if it was?

Solar is cheaper and can be expanded rapidly sooner.