There are solutions to this- driving through eastern Colorado and west Kansas you'll find many farmers using no-till techniques and planting winter cover-crops that create topsoil and increase soil quality. Farmers have a vested economic interest in keeping the soil productive.

Meanwhile from what I understand from talking with some friends in agricultural engineering in places like California where farmers expect to be pushed off their land eventually by rising land prices they are using destructive practices to extract as much as they can before they go defunct.

The USDA is offering incentives for good soil stewardship and the 2018 Farm Bill featured a number of soil health policies, such as restrictions on pesticides and a soil carbon pilot program: https://www.nrdc.org/experts/mae-wu/final-farm-bill-blossoms...

> in places like California where farmers expect to be pushed off their land eventually by rising land prices they are using destructive practices to extract as much as they can before they go defunct.

Assuming the land is going to be used for non-agricultural uses (residential/commercia, covered in some material in some way) and "destructive practices" means over-farming, but not otherwise polluting or causing damage, I'm not sure I see a problem with that (but I may not be thinking of some consequences).

Then again, that's a lot of assumptions...

There may be a tiny minority of farms in pristine locations that will eventually get pushed off their land, but I suspect the vast majority are in areas where the land is absolutely undesirable for anything besides farming. If you've ever driven across California's central valley you'll know what I mean.

California will one day be uninhabitable by 99.999% of the population. The rich will have to fly in day workers. It would be a good time to start investing in drone taxis, I suppose.

Downvoted for hyperbole.

Current world population about 7B, 0.001 of that is 700,000. That's less than the population of San Francisco.

If we do this with just the US population, you get about 3000.

“Tree Crops: A Permanent Agriculture”, by Russel Smith (1929) is an excellent, well sourced book on the subject. The title also hints at the origin of the term “permaculture”, popularized by Bill Mollison.

There’s a lot of solid scientific evidence out there for soil repair as carbon sequestration; in fact the appendix of the IPCC report that shook the world last year lists soil repair as one of the top things we can do to address climate change.

1: https://www.goodreads.com/book/show/714112.Tree_Crops

I was just about to post something similar. From what I've been reading, fully optimized land management can both sequester an enormous amount of carbon and provide better crop yields.

The scary part is that even if you cannot provide food to even, let's say 3% of the human population, it will create massive destabilization, initially in the part of the world affected, then globally. I remember that at the start of the various Arab Spring revolts, protests were about the cost of food.

I have never been to Egypt, and maybe I have a distorted view of the situation there, but I don't understand how it can sustain a population of 100 millions, on basically a thin strip of arable land around the Nile surrounded by a huge barren desert. It can not be sustainable.

First of all, the Nile basin covers 32% of the area of Egypt (330 000 km²), which is a bit more than the size of Italy who supports a population of 60 million.

Secondly, due to the climate they also get two-three harvests per year.

That said, they still import nearly 20% of their food - https://tradingeconomics.com/egypt/food-imports-percent-of-m...

Thanks, it put things in perspective.

The river quite literally brings life to that 'thin strip'. Without the Nile it would be desert.

Isn't food instability a contributing factor to the crisis in Syria?

From what I understand it led to (young) people leaving the countryside to live in cities. This lead to large congregations of unhappy unemployed young people, all new to a particular area. These people then grouped up and protested about the ruling regime, which was the start of the current crisis.

Exactly, that's a good summary as far as I understand it. In other words, we're already seeing the impacts of food insecurity as a result of climate change and it will only get worse from here.

None of the previous comments on this topic indicated that the food instability was caused by climate change. Are you just assuming that?

From what I can recall it is due to an overlong drought. This could be due to climate change or not.

There are arguments from both sides: https://www.inverse.com/article/25318-aleppo-syria-conflict-... http://www.sussex.ac.uk/broadcast/read/41428

Also worth remembering that something as complex as the Syrian Civil war is bound to have multiple causes.

I'm not sure if you have to verify as some sort of investing class to access but GMO (Grantham's fund) has a lot of papers published. This: https://www.gmo.com/docs/default-source/research-and-comment...

has that quoted figure and references this: 2 D.R. Montgomery, Dirt: The Erosion of Civilizations, University of California Press, 2007.

> Generating three centimeters of top soil takes 1,000 years, and if current rates of degradation continue all of the world's top soil could be gone within 60 years, a senior UN official said on Friday.

https://www.scientificamerican.com/article/only-60-years-of-...

> "Generating three centimeters of top soil takes 1,000 years,"

Such a vague assertion leaves me with more questions than it resolved. Topsoil should properly be measured in volume, not distance. Presumably they mean a given area will gain three centimeters in 1,000 years, but what area and under what conditions? There are some environments with zero topsoil and some environments with quite a lot of topsoil, so is that "three centimeters per 1,000 years" figure a global average for natural topsoil renewal? I can't imagine how that's a valid measure of anything. You'd have massive regions totally devoid of topsoil like the Gobi Desert dragging down global averages.

And what about anthropogenic topsoils? Maybe one of the most famous examples is terra preta in the Amazon, which not only is madmade but reportedly regenerates itself at a rate of 1 centimeter per year (a few hundred times faster than that "3 centimeters per century" figure..)

It's also just wrong.

Maybe this is true under "natural conditions" (however you want to define those). But intentional farming practices can produce this much top soil every year. The problem is that few farmers use those practices. But I do, and I can tell you that planting green fertilizers and nitrogen-fixing cover crops, and then plowing them under, will produce pretty good topsoil very quickly.

Yep. You can definitely "grow" topsoil very very quickly. Similar to the ratio between the productivity of land for hunting-gathering and agriculture.

Source: Farming & gardening background in the midwest.

> Topsoil should properly be measured in volume, not distance.

Presumably topsoil generation is proportional to land area, and volume per unit area reduces to distance. 3 cm per 1000 years is equivalent to 30 m^3 per km^2 per year.

That said, the number still seems wrong. Table 5.2 in [0] indicates that regeneration rates range from 0.25 mm/year to 2.0 mm/year. 3 cm per 1000 years is equivalent to 0.03 mm per year, almost an order of magnitude lower than the lowest rate in that table.

[0] http://www.fao.org/docrep/009/t0733e/T0733E06.htm

> Topsoil should properly be measured in volume, not distance

Should it though?

And regardless of how clear or unclear that is, I gotta say I dislike seeing when the sum of a multitude of reports is expressed in a headline, only for people to nitpick through it without even attempting to check the actual methodology for themselves.

1 cm/year is 33 times faster than 3 cm/100 years, not a few hundred times faster.

AFAIK terra preta is far from fully understood, and farther still from being widely used. Very cool stuff though.

Only responding to the one part of your comment, it was 3cm/1000 years, so a few hundred (333) years was accurate.

You are both right, farmers measure rainfall in inches, (which translates to inch acres) so it is both a mesurement of distance (inches) and acres (how many they own) think of centimeters per year the same way. Yes topsoil can be made much faster than these numbers given but there are consiquesnces, methane is released from the process of composting which is 19 times the greenhouse gas than the CO2 released from burning. Also the volume is affected by soil compaction and the production potential is affected by increased salinity from unused fertilizer, the outlook is scary but humans always adapt.

> "ROME (Thomson Reuters Foundation) - Generating three centimeters of top soil takes 1,000 years, and if current rates of degradation continue all of the world's top soil could be gone within 60 years, a senior UN official said on Friday."

The article is crap, it doesn't answer any of my questions. You think I didn't check it before I commented? It quotes Maria-Helena Semedo throwing out that figure without any clarifying context or explanation. Without saying where it came from or what it's actually a measurement of.

Also, three centimeters per one thousand years is much slower than three centimeters per century.

The statement was about the global reserve, so clearly these are all global averages.

I don't see volume being very natural reporting unit as farming usually counts by area, so reporting a total volume just forces everyone to convert to length themselves.

You want more details, read the Status of the World’s Soil Resources report: http://www.fao.org/3/a-i5199e.pdf

Farmers know their area, so when they count rainfall in inches it's implicitly volumetric.

The problem with that UN official quote is the area being talked about is poorly defined. Is it the global average for all farmland, or the global average of all land area (including Antartica?) The official doesn't clarify, but it matters because if it's the later that number is obviously being suppressed by regions that lack topsoil and were never considered arable in the first place. How long does it take the sand dunes of Gobi desert to create a centimeter of top soil? And I'm sure permafrost regions create new topsoil at an absolute snails pace if at all (although global warming might change this!) It seems obvious that regions like this will make that global average number seem a lot more dire than the situation actually is.

Don't get me wrong, I'm confident that topsoil erosion is a real problem that needs to be addressed. But I think that number; without the official providing any clarification, justification or context for it; qualifies as alarmism. It's obviously not going to take farmers 1,000 years to regenerate three centimeters of top soil on their fields.

I can't wait for the final report of the IPBES, alias IPCC for Biodiversity. I've heard that the conclusions should be even direr than the IPCC's reports on climate change and will require more urgent actions than the one needed to limit/decrease CO2 emissions. When the media will start writing about it (there's a word for that: anthropocene), we'll realize that the two must be fight at once (and fast), and that we'll have to completely reinvent our industrial system in a few decades. IMO, no civilization has ever faced such a challenge, and this time, it isn't a country/empire/species at stake but the biosphere's. Buckle up !

There’s a permaculture technique called Keyline Irrigation — one of its claims is that top soil can be generated at a much quicker pace as the result of a practice known as subsoiling, wherein a large blade cuts deep grooves into a field. The blade cuts plant roots which in turn decompose, and aerate the soil, providing pathways for water to infiltrate.

It hasn’t been scientifically validated. Anecdotal reports from farmers like Mark Shephard are that it works. [1]

1: https://books.google.com/books/about/Restoration_Agriculture...

"> Generating three centimeters of top soil takes 1,000 years, and if current rates of degradation continue all of the world's top soil could be gone within 60 years, a senior UN official said on Friday. https://www.scientificamerican.com/article/only-60-years-of-...

Ridiculous claim made by "UN official". Sad state of modern journalism. Are we 6 cm away from discovering Roman artifacts in any of the fields across Europe? Or we have to dig a bit deeper?

Does anyone really believe that?

Not anyone who ever had a large compost pile in the backyard...

>Well, that's definitely a scary framing. Does anyone have sources for this specific prediction?

I read somewhere that the energy required to produce a unit of basic food products (say, wheat) has been multiplied multiple times over the last centuries because of overuse and pollution - despite the high efficiency of current machines and chemical fertilizers. I can't find the source but would be glad to find it or a refutal.

I don't believe that study was regarding climate change but rather the unsustainable nature of modern agriculture. I am a hobby farmer and have done some study into the nature of fertilizer, problem is that our fertilizers destroy the soil and so each year it requires more ferts than the prior year. I believe that the study was referring to this trend.

I agree. The more I read about climate change, the more I realize it's only one part of the anthropocene - so I often end up mixing the two. Anyway, if you do have a source for the diminishing returns of energy use to produce food, please share!