You must log in or register to comment.
- 2 days
As far as I can tell, the LPI is defined as such:
-
Divide the world into realms and all animals into species groups.
-
For each species, divide the realm into populations, and consider the percentage change of those populations relative to 1970. Take the mean of all percentage changes.
- For example, if a species of bats exists in two populations, and one population went from 1000 to 0 and the other went from 10 to 100, then the species’ average change is (-100% + 900%)/2 = +400%.
-
Take the mean of species within a species group.
- For example, If bats and deer are the only species of terrestrial mammals, and bats “went up 400%” per above while deer went extinct (-100%), terrestrial mammals “went up 150%”.
-
Take a weighted average from among realms and species group, using a weighing that is not specified.
The fact that the LPI is down to 0.27 while half of species declined means that populations have increased mostly among species groups and locations that the authors think don’t matter as much for planetary wellbeing.
-