[betageek]

Is this true? It is hard to believe that killing off 60% of animals on the planet would leave us with a functioning ecosystem. It's also very hard to work out what the facts are here without finding yourself in climate change denial land, a place I do not want to visit.

[cbkeller]

Geologist here! The report in question [1] and supplement [2] seem pretty think-tank-y, but I would say they pass the sniff test to first order (if we have a biologist or ecologist around, they could probably say better). The focus on animals makes it relatively plausible -- these are charismatic and easy to observe, but a lot of the ecological heavy lifting / biogeochemical nutrient cycling is really carried out by microbes, which are are probably doing better. Microbes also represent most of Earth's genetic diversity, and will pretty certainly survive any mass extinction we throw at them.

In any case, the Guardian article is correct in claiming that

>Many scientists believe the world has begun a sixth mass extinction

This is pretty well accepted among geologists and paleontologists, as far as I've seen. Here's one relatively recent perspective on the issue, which covers some of the back-and-forth: http://science.sciencemag.org/content/360/6393/1080.2

[1] https://s3.amazonaws.com/wwfassets/downloads/lpr2018_full_re... [2] http://awsassets.panda.org/downloads/lpr2018_technical_suppl...

[titzer]

> a lot of the ecological heavy lifting / biogeochemical nutrient cycling is really carried out by microbes

What really worries me is what is going to happen when all those millions of tons of microplastics become nanoplastics and are spread far enough to become part of the foodchain, even down at the microbial level. The dark end of that space is pretty terrifying for life on Earth, IMHO.

[cbkeller]

Interesting point. It looks like there may be negative consequences for eukaryotic algae / phytoplankton [e.g., 1], but on the plus side some prokaryotes are able to usefully metabolize plastics and "bioremediate" the problem a bit [e.g., 2]

[1] https://www.sciencedirect.com/science/article/pii/S0166445X1... [2] https://link.springer.com/article/10.1007/s00253-018-9195-y

[betageek]

Thanks for at least trying to answer the question, just to be clear, I'm 100% convinced in climate change and some kind of extinction happening, just querying the '60% of all animals' headline.

[cbkeller]

It also looks like the claim here is something like "the total animal population has decreased by 60% on average over all studied localities since 1970" rather than the more dire "60% of all animal species have gone extinct since 1970" so we're not anywhere near the 90% species extinction of the Permo-Triassic yet!

[ifdefdebug]

>> Many scientists believe the world has begun a sixth mass extinction.

>This is pretty well accepted among geologists and paleontologists

Do they believe humanity will be one of the survivors?

[c048]

Sigh.

a) This is not in their field of expertise. b) If there is any species that has the best chance of survival, it's humanity.

[Chris_Jay]

Oh now you're just tempting fate. Surely that distinction goes to the cockroaches?

[cbkeller]

I haven't seen much of a consensus on that one yet!

[seren]

How do we know with still have a functioning ecosystem ? For example, there is a massive extinction of bees going on, the only reason we don't see a massive impact is that we have industrialized bee productions.

https://theconversation.com/a-bee-economist-explains-honey-b...

> In 2017, beekeepers in North Dakota, Idaho, Florida and other states shipped 1.7 million colonies to California to pollinate almond trees, or about 64 percent of the total population as of Jan. 1. The bees travel in semi-truck loads of 400 to 500 colonies each.

[maxerickson]

US honeybees are livestock, they aren't a native species.

They travel in semi-truck loads of 400 to 500 colonies each!

The apparent decline in native insects is very concerning.

[Chris_Jay]

Wild honeybee colonies used to exist, though granted they were a new import.

[pjc50]

Ecosystems are mostly local - what this represents is the erasure of the rainforests and their conversion to largely animal-free cropland. The impact of that is yet another large CO2 emission.

[titzer]

> Ecosystems are mostly local

I think this is a misconception. Everything is interconnected. Did you know that some species of bird migrate up to 8700mi every year? (https://en.wikipedia.org/wiki/Bird_migration) So do many insect species (butterflies!), fish, whales, sharks. And, as apex predators with wide ranges, sharks have a huge impact on ecosystems across the globe (and losing them is very, very bad: https://www.livescience.com/9716-loss-top-predators-causing-...).

We're royally fucking up the entire planet.

[jessriedel]

> the erasure of the rainforests and their conversion to largely animal-free cropland.

Additionally, even when natural lands are converted to grazing land for farm animals, rather than cropland, the number of animals is still likely to decrease. Wild animals are strongly tilted toward small species and the same piece of land will support many fewer large animals even if the total animal biomass is similar.