This is a famously difficult to interpret statistic. It’s an excellent survey, but you probably do not understand what the number means (because it is a weird number). In particular, only half of species surveyed showed a population decline at all, the other half either grew or were stagnant.

The authors of the LPI go to great lengths to explain this. Yet, there is inevitably a long list of headlines claiming that we’ve “lost 73% of wildlife”, “73% of species have gone extinct”, or “73% of species are declining”. All of these are incorrect.

• our world in data

To give you another sense that this number is weird:

The 2022 Living Planet Index reported an average decline of 69% since 1970. In 2024, it reported a 73% decline. And this latest report finds the same: 73%.

So, what exactly is this 73% number?

To obtain the final LPI number, researchers take the geometric mean of the rates of change across all these populations. They also provide different weights to different populations, which affects the final result.

I don’t know other places where I’d take the geometric mean. I have no intuition for it. So… caution advised.

Great; that describes all functions, so we’ve nothing to worry about.

Cool; walk me through attention layers plz.