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Comment by leros | Hacker News Reader

I know some farmers in North Texas where they are pulling water out of a depleted aquifer. The water is starting to get salty so they're adjusting to salt tolerant variants of their crops. The ground is also starting to drop due to the aquifer draining. It's crazy to see

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In the Santa Clara Valley farmers pumped enough water out of the ground in the early 20th century the ground dropped a dozen feet in some areas. Bad thing too is that once an aquifer settles like that it's carrying capacity is permanently reduced.

Also in southern California there is a fair amount of previously productive farm land that is salted up and useless. That'll happen to the north Texas farmers you've mentioned. If they're having to switch crops they have another ten to twenty years and it's all over.

Edit: Even better Jakarta is sinking so bad because of ground water pumping that the government plans to abandon it.

It's odd that foreign media reporting the Indonesian government plan to move the seat of government from Jakarta to Borneo as primarily motivated by the sinking of Jakarta (it affects the northern part of Jakarta, while the goverment is mostly operating in Central Jakarta), while the other more important (to the government) reasons are usually under-reported, such as to reduce the java-centric development, improving the government's efficiency by moving various government agency closer together instead of scattering everywhere over the huge megacity with traffic jams everywhere, and improving the government image because foreign diplomats will arrive in a pristine, green city instead of concrete jungle with bad air and traffic jams everywhere.

I remember reading about how in the Soviet Union, there were places they were irrigating with brackish water and how they were now infertile. The obvious conclusion was that the Soviet economic system was busted to permanently destroy land for some temporary gain.

The American equivalent is the dust bowl. The ancient equivalent is the desertification of Mesopotamia. Etc. etc.

Humans are bad at long term thinking.

Which species is good at long term thinking?

Termites are pretty good. It's too expensive for them to rebuild their nests all the time so they don't destroy their surroundings.

Many animals move on before they destroy the fields and return later once it's regrown.

Probably not much thinking but this is how your species survives. Perhaps humans think too much.

These days I feel like it's more that every attempt at central planning gets weighted down in conspiracy theories.

Sadly though, the public's reaction isn't totally unwarranted due to what has become acceptable behaviour for politicians.

We've been farming for 10,000 years, and the vast majority of farm land is still fertile.

We have not been farming for 8 billion that long. The scale of what’s happening right now is unprecedented.

And thanks to fossil fuel fertilizers and land degradation a lot of topsoil is less than 60 harvests from being degraded completely.

Why can’t it be amended? My region has pretty shitty clay soil but I’m able to mix in compost, mulch, and other amendments and grow all sorts of tropical fruits and other plants that shouldn’t grow here. Am I missing some reason why the farmers have to rely on topsoil?

What do you mean, why do we have to rely on topsoil? That's what almost all food grows in. What else would you effectively grow food in? What you're doing by adding compost is basically creating topsoil yourself. Amending can only go so far. In some cases it's literally just been degraded away like when deforestation causes land to be more susceptible to erosion by flood or landslide. You may be able to make soil amendments work while you have fertilizer and added nutrients derived from fossil fuels, but once those aren't economical, you're getting out what you put in naturally, which is a lot less than modern industry has acclimated us to, and probably a lot less than in historical times if the topsoil quality was drained of nutrients that can no longer be replaced.

That’s different, it happened under capitalism, so it was an unforeseeable natural disaster that doesn’t reflect on the system in any way.

Is it close to these huge sinkholes in Turkey? https://www.dailysabah.com/gallery/turkish-farmers-worry-abo... Because these in Texas seem tiny in comparison https://www.texastribune.org/2023/08/16/texas-drought-heat-a...

I did the math once and the amount of water we’ve pumped out of the aquifers worldwide and not replaced is worth more than a mm of sea level rise.

Related: Humans pump so much groundwater that Earth’s axis has shifted, study finds

https://www.cnn.com/2023/06/26/world/pumping-groundwater-ear...

I used to joke that once the ice caps melt and fiddle with the earth’s angular momentum, I’ll have enough hours in the day to get everything done. Better WLB these days. And also ice caps melting is less funny than when I said it.

Correction: 10 cm

https://news.ycombinator.com/item?id=39736050

Please show the math and sources, I would love to see the sauce.

OK, I am finding that my memory was faulty here. Global aquifer depletion isn’t equivalent to 1 mm of ocean volume. It’s equivalent to 3 mm of ocean volume per year (2010: https://www.ngwa.org/what-is-groundwater/About-groundwater/f...)

    Groundwater is the world’s most extracted raw material with withdrawal rates currently in the estimated range of 982 km3 /yea

Surface area of the ocean:

361,000,000 km²

1,000,000 mm per kilometer means 361 km³ per millimeter of sea level, ignoring inundation.

The USGS estimates that just the US has lost 1000 km³ from 1900-2008, most recently (2008) at rate of 25 km³ per year which is at least another 400, so let’s call it 1400 km³ which is almost 4 mm. Just for the United States.

I can no longer find the studies that estimated global depletion of aquifers. I don’t know if my queries changed or SEO rotted the search engines. But if it’s anything like the US, (2.5% a year) then we are over 40,000 km³ globally. Which is about 10 centimeters of sea level rise we could mitigate if we could refill all of the world’s aquifers.

I know California has been experimenting with this, but we know with boil orders that untreated water made it into the water supply. What happens when the same thing happens with groundwater injection wells?

There’s a calculator that works out how many acre feet of water it takes to raise the ocean level, and the UN has estimates on total global aquifer depletion. There were a couple ways to calculate it. I’ll see if I can reproduce my work.

Me too because that sounds impossible to calculate.

What difficulty do you see? It's not going to be enough to appreciably change the ocean area, so isn't it just volume divided by the area of the ocean?

I think it would be 1) how accurate are aquifer and coastline topography measures (1 mm wouldn’t be far off but what about a meter? That’s a lot of inundation). And 2) how much has subsidence permanently decreased the carrying capacity of aquifers?

It could be a thing where only 50% of what is extracted can be returned. Either theoretically or safely (eg, earthquakes).

Makes sense, thanks.

Permeability, amount of precipitation, land usage, evaporation, avg temperature, temperature variation, soil composition, erosion, wells, flood plain, wetland, etc.

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