A quick search for 'global aquifer depletion' yields

"Scientists had long suspected that humans were taxing the world’s underground water supply, but... major aquifers [are] indeed struggling to keep pace with demands from agriculture, growing populations, and industries such as mining." ... "The situation is quite critical" (https://www.washingtonpost.com/news/wonk/wp/2015/06/16/new-n...)

If someone talks about water usage (usually in a generic 'it takes X gallons to make a Y, so you should feel bad about doing/using Y' format) without regard to the specific sources then they are trying to bullshit you. If they talk about a specific source and use then keep reading to see if the rest of their argument holds up to scrutiny.

But ultimately it's the same conversation - any manufacturing of perishable / low-cost-to-weight ratio (e.g. cement is almost always produced at a factory within 50 miles of where it is used) at industrial scale is being done in a consistent, distributed way at many different locations around the country/world. If those processes damage vulnerable environments, they need to be looked at and modified.

Concrete (as well as mortar, stucco, and other such products) is made locally, both dry and wet mix. Cement is made in remote areas, typically near the limestone quarries, because the process involves large, dirty, smelly kilns.

They LOVE farming out here since there is virtually no rain or weather events to complicate things. They have everything down to a science and a tight schedule that rarely if ever changes. We use up 90%+ of the Colorado River for this one purpose. We then ship these all across the nation using more resources. Seems a bit wasteful.

So how much water to produce a head of lettuce?

Answered my own Lettuce -- 15 gallons

Chocolate (One Pound) -- 2847 gallons!!!!!

Ain't I a ray of sunshine this morning?

Also I have no idea where they are even getting this number. I think they are counting everything from rainwater that falls on the sugar beets, to the, water used by steam engines to produce electricity. But it's hard to tell because they don't explain the figure at all.

For a bit less than 50 years I've heard continuous and constant boosterism that the burbs will migrate back into the city center. No really, this time we're serious about it, etc. Its a cliche now. However a much more interesting migration, is over the next generation or two, most of the west half of the USA will have to migrate back to the east half, assuming they want to drink water or grow plants. Its going to be interesting to watch, at least for today's younger kids to watch.

Note that the land will support some people. In 2030 the west is not going to be empty, any more than it was empty in 1830. It just won't have as many people as now.

1) The use of a (small) part of the west's capital to pipe water in from further away

2) Opportunities for multiple orders of magnitude better conservation.

3) Desalination

None of those are as easy as "just wait for rain" but as long as it's cheaper than the entire state of California ($10 trillion?) then it's not a financial hardship compared to "everyone just leave."

Sure you can: https://en.wikipedia.org/wiki/Water_splitting

We also can create temperature gradient by adding shade at some areas, e.g. using SO2 at altitude of about 20km.

I'd drink soda.

With current knowledge and level of technology humanity has, we can make almost anything by applying energy to shuffling dirt. Need gasoline? We can synthesize it. Need gold? We can recycle it out of stuff. Need drinking water? We can make it out of almost anything.

All that's needed is energy, which is something we don't have much of. Last time I checked we didn't have the world full of nuclear reactors. Until we hit a sustainable and ridiculous energy abundance, we can't assume we can fix any global problem with energy - there's not enough of it to go around.

EDIT: Wording.

One key questions for rulers and governments from antiquity is how to allow the population to gather energy to survive. It could be farming, or building oil wells and then hand out the profits or build a service economy around the oil.

I couldn't figure out how to maintain a modern population without oil (more people same amount of land) until I saw this on HN the other day https://medium.com/invironment/an-army-of-ocean-farmers-on-t...

Zero input food. Can be used to generate ethanol. All you need is open ocean.

Food for thought.

But we can with nuclear plants, and I'm thinking garden variety fission plants, not the always-30-years-from-now fusion ones. There are various areas where we use fossil fuels only because its more convenient - e.g. ground transportation. We can go electric with most of it. Fertilizers - I'm not sure if petroleum is a necessary chemical component or just energy delivery vector for the production process. Plastics are I think the only area where we can't easily sidestep fossil fuels. But with enough electricity we can still synthesize the compounds we need for those processes.

Or we could sit in top of our coal power plants slurping oil, wait for the magical thorium reactor and/or solar power to become another 10 times more economical.

[0] - http://www.withouthotair.com/c24/page_162.shtml

>> "A once-through one-gigawatt nuclear power station uses 162 tons per year of uranium"

>> "World total (conventional reserves in the ground) 4.7[million tons]"

https://en.wikipedia.org/wiki/World_energy_consumption

>> "The IEA estimates that, in 2013, total world energy consumption was 13,541 Mtoe , or 5.67 × 1020 joules, equal to an average power consumption of 18.0 terawatts.[3]"

One gigawatt nuclear plant uses 162 tons per year.

The world uses 18000 gigawatts per year. (40% oil, 10% coal, 15% natural gas, 35% other).

If all the fossil fuel-based energy were replaced with nuclear power, the nuclear power plants need to provide 18000 gigawatts times 65% = 11700 gigawatts.

11700 gigawatts times 162 tons of uranium is 1.9 million tons of uranium, per year.

The world's conventional reserves of 4.7 million tons will last for three years.

The 22 million tons in Phosphate deposits will last for another 10 years. (if and when methods to mine them economically are discovered)

Perhaps the seawater uranium will come in time, but as yet it is not an economical method of uranium extraction. The cost needs to be reduced by 5 to 10 times.

That doesn't follow at all. Why not?

There's plenty of sunlight in the areas with most of the people, and the areas with most of the farmland. We have storage solutions--they're still a little expensive, but they're certainly getting close.

If our current energy came from hydroelectric or geothermal could we replace it with solar? Your statement seems like a complete non sequitur.

I think that solar and nuclear are the only sustainable power generation methods these days. The rest are either bad for the environment, or ineffective.

I can't accept the morality of handing stewardship of spent nuclear fuel to my children and their children for a thousand generations. Would you still want to be caring for a monster left to us by the people who wrote on cave walls?

As far as a DGR, I'll believe it when a nation other than Finland has shovels in the ground to actually build one.

However, it's not _that_ dangerous. Even if containment is breached, it generally stays in the same place and can be collected and put back (happened a lot of times).

Asse II springs to my mind: https://en.wikipedia.org/wiki/Asse_II_mine An old salt mine used to store low/medium radioactive waste that's under threat of collapse due to ground water. There are plans for the retrieval, but success is far from guaranteed.

Also, honestly, I don't see the point. The amount of nuclear waste we produce is minuscule compared to other equally or more dangerous chemical substances. Besides wasting perfectly good rocket fuel, destroying it this way would rob us of opportunity to reuse it in the future - hell, we already know how to reprocess some of the spent nuclear fuel for next-gen fission reactors!

https://en.wikipedia.org/wiki/Breeder_reactor#Waste_reductio...

2) What monster could be left by stone-age people to us that modern technology couldn't handle?

Modern spent fuel processing methods are great and quite safe (vitrification / underground disposal). I can't imagine a newsworthy worst case scenario with vitrified containers.

2) As long as we assume that society continues on its current trajectory forever, then yes, there's nothing to worry about. But if it's true that we're in the twilight years of US dominance or relevance as a world power, then we could be in for a significant period of upcoming political/economic turmoil.

So here's another way to look at it: How would the monks and agrarian fiefdoms of the middle ages been at handling a monster leftover by the Romans?

EDIT: Fixed wording in the original comment; I hope it's clearer now.

In reality, time is the metric the matters, human time. All that stuff you talk about costs human time to build. That's why it's not being built - it's cheaper to do something else.

Once you have a robotic army capable of mining resources and building everything you want, including rebuilding itself, you can just have them throw up a bunch of solar panels and have enough energy for desalination.

All of our problems could be solved with an unlimited amount of energy applied to them. Most of them were created that way too.

Energy is one of those strange things, where consumption is not necessarily destruction. You 'used' a joule of energy when you heated up your coffee this morning, then dumped the waste heat to the rest of your kitchen, where it became an input for another part of the cycle. The energy did not go away when you consumed it, and in this case most of the energy 'used' in the production of a cup of coffee was never lost.

[I kid, I kid, I know you meant negentropy, but I just couldn't help myself.]

The trouble is just that many popular sources of energy has lot of negative effects ;-)

"Energy is about the only resource where this doesn't hold true."

Now, whether we can effectively use the energy is an entirely other question. There's plenty of technical limitations. But in a closed system there's no reason an object cannot have perpetual motion with perfect energy recovery. Of course, closed systems don't help us, because they cannot exert useful work outside of the system.

https://en.wikipedia.org/wiki/Reversible_computing#Physical_...