[dredmorbius]

we do have the ability to make relatively stable environments in which the necessary components of an ecosystem can thrive.

Only with the inputs of massive amounts of energy and additives -- fertilizers, pesticides, and cultivation supplied directly by humans (or our machines).

The energy intensity of modern ag is many, many times higher than of natural environmentments. Food production in the US requires ten calories of fossil energy for every calorie of food energy produced, in Europe it's closer to a 5:1 ratio.

A sustainable agricultural system would require that the output energy be greater than the input.

[kazagistar]

We have only been at it for so long, and barely gotten started in earnest. Plus... energy and additives are not "external" to the system: they are provided by a natural species in the system, us.

Yes, we do need to get to a point where we are not relying on expendable reserves to run the system. But it certainly is possible that we will engineer a better ecosystem (robot cultivators and solar panels included) that results in a more efficient net benefit for us.

[dredmorbius]

May I suggest Howard T. Odum's works, in particular Environment, Power, and Society and Energy Basis for Man and Nature.

In the former he argues strongly about the mechanisms by which humans have enhanced ag productivity in plants and animals.

Generally, there are the following methods:

Mechanical tillage, breaking up soil to make it easier for plants to grow and spread roots. This also, incidentally, increases topsoil loss to wind and water, such that many farms are effectively "mining" topsoil faster than it's being replaced.

Artificial irrigation. This varies from simply collecting and distributing water via gravity-flow reservoirs and irrigation ditches to transporting water and irrigation pumps and pipes to water mines which, again, deplete a resource faster than it is restored -- as is the case throughout the eastern Plains states in the US, much of China, and especially in the Sahara and Arabian penninsula where water tens of thousands of years old is used to irrigate crops, from underground reserves which aren't being replenished. Water availability itself is becoming a significant concern, with major droughts in the past 5 years disrupting crops in Russia, the United States, China, India, and of course, as is rather chronically the case, Africa.

Fertilizer. Nitrogen, fixed at great energy cost from the air using fossil fuels (mostly natural gas). Phosphorus, which is in extremely limited supply. Potash, rather more abundant, but still with only a century or three of reserves at present rates of use.

Selective breeding. Plants and animals have only so much metabolic budget. By diverting energy away from specific uses, especially immune response, physical activity, and foraging needs, more can be devoted to growth. This works to an extent, but is greatly facilitated by ...

Antibiotics and pesticides to reduce illness and parasites. Fun fact: the first virus identified wasn't a human illness but the tobacco mosaic virus. Antibiotics and pesticides mean that animals and plants need devote less of their own energy to competing in their environment. Unfortuately, both ultimately create resistance, a problem later to both the ag products themselves and quite possibly humans, especially in the case of antibiotics. Moreover, bred cultivars requiring such treatments don't compete where they're not available (similarly for fertilized crops, above).

Mechanical pest reduction. Removal of weeds, or native long-lasting plants which compete for ag lang productivity (e.g., natural plains, tropical rainforest).

Solar panels compete directly with plants for solar energy. At best you want to put them in regions plants cannot grow.

The history of ag enhancement is relatively brief, but it's all been accompanied either by vast investments of energy, or by the application of either materials or technologies themselves requiring or based on vast applications of energy. Even the father of the Green Revolution, Norman Borlaug, cautioned that he'd only provided at best a brief respite from hunger.

It's not so long ago that major famines still ruled the world, with major instances in the 19th century (Ireland 1845-52 killing 1.5 million, China 1850-73 with a population drop of 60 million), and 20th (1920s in Russia, 5 million, and China, 3 million, 1930s Ukrain Holdomor, 7-10 million and China, 5 million, and the Great Chinese Famine of 1959-61, 15-43 million). And that's just a set of highlights, see: http://en.wikipedia.org/wiki/List_of_famines

In many cases, 30% of regional populations died (or in some lucky cases, emigrated elsewhere, as in Ireland), in others historically 50-90% of populations were wiped out. I'd suggest you not think this cannot happen again.

I'll also advise you that this is a topic I studied, extensively, in school.

[NotAtWork]

Some of your problem predictions are 100+ years in the future. I generally regard these as nonsense.

Looking at the relative rates of technical growth and computing power, it's incredibly unlikely that we'll be able to accurately pick out what the future is going to bring.

Examples of technologies that are expected in the next 50-100 years: 3D printable organs which can be transplanted, based on your own stem cells; the first smarter-than-human general purpose AI; fusion power; the ability for bioengineering to be done with a home lab kit. (We're actually at the cusp of the first and last of these now.)

That level of bioengineering, computing prowess, and cheap power will have an incredibly hard to predict effect on issues like food production, ecosystem maintenance, etc.

So which of your warnings are only problematic at 100+ years?

[dredmorbius]

Some of your problem predictions are 100+ years in the future. I generally regard these as nonsense.

Why?

I don't.

Technology is a function of available energy (Tainter, White, Prigogine), not vice versa.

I find projections of viable sustained fusion nonsense given 62 years of failure to achieve it. Every last single other energy source tapped by humans, sustained nuclear fission included, had previous exemplars occurring on Earth, and was adapted by humans either before history, or (in the case of fission) within a matter of single-digit years of initial attempts.

But enjoy your Panglossian vista.

[NotAtWork]

> I find projections of viable sustained fusion nonsense given 62 years of failure to achieve it. Every last single other energy source tapped by humans, sustained nuclear fission included, had previous exemplars occurring on Earth, and was adapted by humans either before history, or (in the case of fission) within a matter of single-digit years of initial attempts.

We have a precious example occurring not on Earth, and within a few decades had figured out how to make large pulses out of it.

Your summary also does a great disservice to the history of using assorted biochemicals as fuel, from various plant and animal oils through initial study in refinements and use of various technologies to aid in their burning.

You can hardly claim, as your statement implied, that we had full mastery of burning hydrocarbons the first time we tried - or that it was anything like when we tried to scale that technology up.

Given 62 years, we have systems with controlled fusion and systems without energy reclaim that are energy positive. A lot of the lack of progress is due to the relatively low level of funding. (The entire cost of fusion research so far is about the same as one stealth bomber.)

I find it unlikely that over doubling the time, with better technology, won't let us solve the capture problem, especially since the facilities of many studies are actually using old technology which we already know how to do better than. (Example: the ignition laser could be purchased in reduced size and with more efficiency for much less than it cost to initially build the laser.)

Your argument seems to largely be "It's complicated to me compared to what I know about these other methods, so can't happen!"

> Technology is a function of available energy (Tainter, White, Prigogine), not vice versa.

This is super unrelated to what we're talking about, because not even you are arguing that we're going to run out of the ability to produce electricity in <100 years.