The Noah's Ark Problem (1998) [pdf]

https://scholar.harvard.edu/files/weitzman/files/noahs_ark_problem.pdf

by tintinnabula • 7 years ago

19 18 7 years ago

scholar.harvard.edu

Is it just me or does the biodiversity crises seem a bit blown out of proportion? I mean, I think it's true that humans are causing faster species loss than the historical average. But I think it's hard to suggest we're an historical anomaly in this regard compared to Yellowstones and meteors and such.

I mean, I know that ecology is very complex and small changes can have big impact. But the world isn't really much different having lost mammoths and dodo birds. And if ecosystems do collapse in catastrophic ways, I find it difficult to believe that the gap wouldn't be filled by other creatures after the previous distribution of life changed dramatically. There's nothing particularly balanced or normal or good about the ecology we had yesterday. It merely is.

Like... If you cut down the Amazon, hypothetically, it's not like that land will necessarily become a barren lifeless wasteland. Other life will move in after the culling, right?

I pretty much always get downvoted for these posts where I bounce heterodox ideas of y'all. And it's totally worth it. I'd like to understand why I don't understand the biodiversity concern.

WRT that guy who's going to post about the medical breakthroughs from rainforest specimens... That's cool and all, but why wouldn't we expect a similar thing to happen with the life that moves in after the hypothetical clear cutting of the Amazon? After all, such events tend to be catalysts for punctuated equilibrium which appears to be responsible for much of the biodiversity we have today.

mavhc• 7 years ago

After 1000 years or more it'll be back to something useful. But if you cut down a forest you're going to use the land for monoculture farming.

Problem is meteors happen once every million years, we're doing this every year.

squirrelicus8• 7 years ago

So replacing the Amazon with monoculture farming, as you say, increases the number of humans the planet can support, right?

fhars• 7 years ago

The problem is not so much that we are causing species loss at a higher than average rate, it‘s more the we are causing species loss at a higher rate than the end-permian extinction event (which no land animal with an adult body mass over 25kg survived).

Life will recover from the anthropocene over the next few million or so years even if we continue business as usual. It will just not be a world I want to die out in.

squirrelicus8• 7 years ago

So that's the jump I don't understand. Why would dramatic decreases in biodiversity cause any dying off of humans at all?

tempguy99993• 7 years ago

Well, smells like a troll but it's a well-phrased one! :) So let's try...

Other life will move in after the culling, right?

Not necessarily. I can't speak for the amazon, where burning down a small patch (traditional agricultural practice for millennia) will leave a hole surrounded by life that will move in, but ecospheres disrupted in the large may break what's supporting that ecosphere.

I read an article about cloud forests being disrupted. A cloud forest gets its humidity from mist, which flows in from the ocean a small (18 inches/50cm?) above the ground. This condenses on anything there, trickles down to the ground, waters the plants. But the plant life had been razed, so there was nothing for the mist to settle on; the soil stayed dry so nothing could grow after. The author of the article was requesting ways to restart that (I made a suggestion, he wasn't too impressed).

Also thin soil can be stabilised by plants so it stays. Kill the plants, the soil blows away. Not sure this is 100% relevant but to some extent it is: https://en.wikipedia.org/wiki/Dust_Bowl

"With insufficient understanding of the ecology of the plains, farmers had conducted extensive deep plowing of the virgin topsoil of the Great Plains during the previous decade; this had displaced the native, deep-rooted grasses that normally trapped soil and moisture even during periods of drought and high winds. The rapid mechanization of farm equipment, especially small gasoline tractors, and widespread use of the combine harvester contributed to farmers' decisions to convert arid grassland (much of which received no more than 10 inches (~250 mm) of precipitation per year) to cultivated cropland.[4] During the drought of the 1930s, the unanchored soil turned to dust, which the prevailing winds blew away"

Related to that I've heard of similar happening, poss. in the amazon, where a thin skin of soil is left in some areas, and gets washed away when the plants are not there to fix it - but I can't provide a reference, so treat that as hearsay.

Disruption can also be astonishingly subtle. This does not answer your question but FYI!: https://www.environmental-research.ox.ac.uk/long-shadow-mega... to summarise, now-extinct megafauna are thought to have moved lots of phosphorous around in their poo, benefitting amazonian plants ("For [the plants] the only input of essential phosphorus comes from dust blown from the Sahara and from the dung of animals that had foraged on the fertilised flood plain."). Humans killed them starting ~12,000 years ago, consequence:

"Nonetheless, the huge amounts of phosphorus that were moved by the collective action of the megafauna has left a long legacy and their calculations suggest that the Amazon is only 2/3 of the way through a transition towards a low nutrient state. Today’s trees are still benefiting from the actions of the prehistoric beasts, but as time is progressing the forests are losing fertility."

's cool and all, but why wouldn't we expect a [medical breakthroughs from rainforest specimens] to happen with the life that moves in after the hypothetical clear cutting of the Amazon?

AFAUI, no. Varied biochemicals are what produces these breakthroughs, which is linked to varied plant life. If that gets wiped out then it will take millions of years for that diversity to re-emerge, so except in the longest timescale, it's gone. However I am not an expert on this. (But frankly do us humans have to be such tosspots towards anything that doesn't immediately benefit us?[0] These things are jewels in their own right, why can't we value them for what they are)

I pretty much always get downvoted for these posts where I bounce heterodox ideas of y'all. And it's totally worth it. I'd like to understand why I don't understand the biodiversity concern.

Well, HTH?

[0](Edit: this summarises it nicely https://i.pinimg.com/736x/18/bd/4d/18bd4d5fe4dc42f7a0b01f4c7...)

squirrelicus8• 7 years ago

FWIW, not trying to troll. I grew up with and was in favor of 90s environmentalism, which seems to mostly have been a success [0]. The latest environment doom and gloom doesn't have the impact and persuasive power that the previous environmental crusade had. Maybe it's just that I had school indoctrinating me then and don't have that now. But I like to believe that's not the only factor here. There's something lacking about the biodiversity and climate change outrages of the late. Some scientific persuasive power, some rigor missing.

Don't get me wrong, I'm generally supportive of the fundamental argument that we ought not to change anything too fast because the consequences are terrifyingly unknown -- that's what makes me a conservative, in fact. However, there's a damn good reason to make that gambit: the elimination of global food scarcity, lifting the developing world out of poverty through industry, allowing developing worlds to be self-sufficient and not dependent on the West. If we lose the Amazon in the process and sea levels rise many meters, as a hyperbolic example, maybe that price is worth paying until we figure out how to not do that. We definitely don't know how to not do it yet. I don't know, and neither does anyone else. Well, that's only half true. We could force every country on the planet to build nuclear fission reactors and electric vehicles at threat of war. But nobody's willing to do that, so it seems like climate change must not actually be that pressing.

In summary, it's risk, and it's scary, but I guess my biggest problem is the idea that it's likely to be bad for us. The opposite seems true, in the medium term. I mean... If Coruscant is devoid of naturally grown life and is fed exclusively from hydroponics, is that planet instrinsically bad?

Sorry for the shallow response and analysis in this post, but I wanted to respond with something before my busy afternoon today. I'll be back.

[0] https://slatestarcodex.com/2019/01/01/what-happened-to-90s-e...

csin• 7 years ago

https://www.youtube.com/watch?v=ovbF0D2wySI

People don't wanna be fcked.

squirrelicus8• 7 years ago

For what it's worth, clear cutting the Amazon and replacing it with farms is probably better for humanity when it comes to Maslow needs

DougN7• 7 years ago

What you’re describing is basically Iceland. It used to be richly forested. It lost its forests and then its topsoil. Essentially an ecological disaster brought on by the vikings. But life finds a way.

The Noah's Ark Problem (1998) [pdf]

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