>> Since the middle of the 20th century, we've lost about 75% of biomass and roundabout the same in biodiversity.
> That’s obviously untrue,
I've provided quite a bit of material for your research. Here are some highlights:
- birds: reduced by 29% (north america) since 1970
- birds: reduced by 20% (europe) since 1980
- ocean fishes: 80% lost in the last 100 years (global)
- insects: 82% lost in the last 27 years (Europe)
- freshwater fishes: 80% lost since 1970
- non-livestock mammals: 78% lost since 1960
I freely admit that the 75% since 1950 number is a ballpark guess. Given the data I refer to above, I reckon it's not far off. Certainly not orders of magnitude and it is certainly not "obviously untrue". We can debate if we lost 75% or 65% or 55%, but given the consequences in any case it doesn't really matter[0].
> so now you’re acting like you were only talking about fish?
What? No. I'm talking about global, total biomass. Every species, every habitat. I'm sorry if that wasn't clear. (Why would you think that I was talking only about fish? Are you trolling me?)
With regards to fish I wrote
> The most visible I think it is for fish. There alone we've lost an approximate 80% since the 1950ies.
To rephrase; the decline of fish is easily observed by the ever diminishing returns of fishery fleets and there's a lot of data about development of the fish population.
> Did you notice that the 45% reduction was over five thousand years, not ~75 years as you claimed?
That's one paper that makes some assumptions and comes up with a model. I have to check it in detail and it looks interesting. But that does not in any way refute the data in the papers I already provided or the very comprehensive report by ZSL[1]. This is a very thorough study that compiles data for 21,000 populations of animals from 4392 species.
To quote: "The population sizes of mammals, birds, fish, amphibians and reptiles have seen an alarming average drop of 68% since 1970.
> Once again, you are saying totally whack stuff to the point where I have to assume you are trolling me somehow.
I'm sorry if you got that impression, because it's not my intention. I thought that I'd made a good case by quoting the research and various papers. I'm not sure why you say that this is "totally whack"; everything is sourced pretty well.
[0] We're staring into the abyss and the abyss is winking back.
[1] https://www.zsl.org/sites/default/files/LPR%202020%20Full%20...