Actually, no, there are, collectively.
Humans have existed, give or take, for a couple million years. In modern form for about 80,000, and with present levels of cognition, for around 10,000.
For most of that time, humans most certainly did affect local ecosystems (and sometimes in significant fashion), but had relatively little impact on the global environment as a whole.
That ended with the Industrial Revolution, and it's only been picking up pace since, with global impacts becoming more evident since the 20th century. Global warming was first postulated in 1932 (by the US Naval Research Lab: http://www.reddit.com/r/dredmorbius/comments/1woc0v/carbon_d...)
The simple truth is that we've got too many people, consuming too many resources, to be sustainable. As with software (fast, cheap, good, pick two), you've got three options from which you can choose two alternatives: big (populations), rich (in resource consumption), or long (in sustainability). Pick two.
Humans can support a large population with high per-capita resource consumption ... for a brief time. Or a high population for a long time ... at very low per-capita resource consumption (and there's no guarantee that present rates are in fact sustainable at low p-c rates). Or a high per-capita resource consumption (high personal wealth) for a long time ... with a low population.
Technology skews this a bit, but in the long term, I suspect, acts largely as an accelerator of resource depletion.
So, yes, your "lots of people doing little" is one option, but what's desperately required is to reduce total population levels. By a lot. The historical record shows that ~500 million - 2 billion might be a sustainable range. I tend to suspect the lower bound of that range.
It doesn't matter if it's sustainable or not, that does not fix this question. What does sustainability matter to the cow you just ate? To the tree you just felled? Why do you get to live, while the plant/animal must die?
It's a question I struggled with for a while in the past.
You've made a number of posts emphasizing that you're not addressing sustainability. In which case: I don't think you're focusing on a particularly relevant part of the discussion.
I see the construction of "having an impact" as a largely irrelevant distraction.
Death is part of the cycle of life. We know that.
Yes, species go extinct. We know that. However the rates vary considerably, and we're at a long-term peak.
As I just wrote in another comment: While moral arguments do get invoked quite a bit, I prefer a more empirical basis for argument. Joshua Greene (http://www.merrimack.edu/live/news/1124-joshua-greene-phd-re...) has some very interesting things to say on moral decisionmaking with which I find myself in generally strong agreement.
For various reasons (and Greene's a neuroscientist who looks as the psychology of moral decisionmaking), we do put an emphasis on people and things who are close to us, both physically and in resemblance (it's easy to feel affection for a tiger or panda than a blobfish or blue-green algae). But in terms of individual choice and having an impact: there's fairly little individuals can do on their own to affect the aggregate outcome.
What you can do -- and some transition / collapse people believe this strongly -- is to take steps to help assure your own individual or tribal (immediate family / community) survival by seeking out viably sustainable areas and lifestyles. The dilemma of personal choice, impact, and action is, I suspect, fairly nonproductive. It imposes a high level of guilt and anxiety without providing much in the way of actual useful productive output. If there's a viable collective outcome it's very likely going to come from some form of collective (or imposed) action.
On the choice thing, I'm finding the RSA Animate presentation I've just been watching "RSA Animate - The Paradox of Choice", by Renata Salecl (http://fixyt.com/watch?v=1bqMY82xzWo) to be illuminating. Choice is, in many ways, oversold. Literally.
No, you're just trying to have a different discussion than I was. I've learned about and talked about sustainability ad nauseam. I studied some of our impacts on the ocean in college, even. But not every discussion even tangentially related to sustainability need be converted into a discussion about sustainability. Especially when, to my eyes, the comment I was replying to wasn't contemplating sustainability! I realize you would have jumped in to my parent with, "sustainability is all that matters, forget about this sympathizing with mammals crap", but while I agree sustainability is VERY important, not everyone agrees it is really the only thing that matters.
Death is part of the cycle of life. We know that.
Yes, but is it senseless to consider the rhetorical question, "why must this creature die for me"? I see it like many other fundamental philosophical questions, like questions about free will. There may not be a clear or good answer, and chances are nothing will change, but it is interesting and even humbling to think about.
"Interesting to think about" and "productive" are distinct. I'm focused more on the latter.
You ultimately can't control what other people are going to do, say, or think. You're the one here expressing frustration with the discussion (and others interpretations of what you're saying). You can engage or not. I try to express myself clearly and cogently, and, if it's clear that there's not going to be some meeting of minds (which can be great, useful, and productive where it occurs), at least try to gain an understanding of where the other person's coming from. Though often that too fails.
This is briliant!!!
Got any ideas on how to do that?
It's simple.
People will die. In Billions. By famine, diseases and war.
I think this is a inevitable future for our race.
Nature made us too god at modifying it for it's own sake. The planet will survive. Maybe not with us but life will.
We are just to stupid and "NOW aligned" to do anything else as a species. That's my opinion anyway.
- Giving women the chance to use contraceptives and making sure their kids survive (else: shotgun approach to procreation) has some impact as well.
- It also seems that population growth goes down with wealth (though then individuals use more ressources).
All of these approaches need at least a generation though. I cannot see an ethical way to change that.
its nice to know that human being environmental impact still trails that of insects...most notably ants.
The other answer is to get rich, which lowers birthrates faster than anything else. Beats a modest proposal.
2) Engaging in sports do not increase your average daily caloric consumption much. Once your body normalizes to your activity level, your BMR is something like 75%-90% of your total calorie consumption for the day. So the incremental cost is indeed low.
3) Fish can be a very economical meat. Feed conversion ratio is fantastic. To my knowledge most environmental damage comes from irresponsible fishers/farmers, not from inherent problems with fish. Crickets (one of the few even more efficient meats) are simply not available.
Don't get me wrong, there are sustainable ways to farm fish and other seafood, but most are a complete ecological disaster. Even something as seemingly harmless as mussel farming has detrimental impacts on the local ocean ecology, as surprise, surprise mussels produce waste and accumulating it in one place is not a good thing.
The problem is not consumption/destruction per se, but the fact that we destroy more than what the planet can build out of solar energy. We're burning the reserves and the means of production.
Also, did you read my parent? Parent was not talking about sustainability and burn rate vs. incoming solar energy or production rate. Parent was talking about mental anguish brought about by the costs his existence poses on the planet- at least, that's what I heard.
re. nonsense, paragraph per paragraph:
1) biking is more energetically efficient than walking.
2) eating any kind of meat daily is not sustainable in the long run, and thus not intelligent (which does not prevent me from eating some, from time to time).
3) You ignore the notion of sustainability. Having some impact does not matter, as long as you stay beneath the sustainability threshold.
4) Your 100 / 110 ratio seems to come out of nowhere. Do you have any data to support it?
I presumed my parent was not primarily concerned with sustainability due to bits like dead orangutans and I like beef, but I sympathize for a fellow mammal. Sympathy and orangutans are not really part of the sustainability picture, which is a separate and large issue I don't intend to dive into right now.
Eating meat can be sustainable. I'm pretty confident if we all ate crickets, there would be practically no sustainability concerns, and we can't all eat quinoa as our protein source anyway. Chile is not able to grow enough quinoa to feed the world (quinoa is a picky plant)
The 100 / 110 is purely invented as a thought experiment, but I consider it to be representative. Your daily BMR is ~2000 Calories. Engaging in activity, sports, games, or mental exercises do increase your caloric consumption for the day, but your body adjusts quickly and your additional caloric consumption for the activity falls quickly into the hundreds of calories for all but the most strenuous activities. Plus, the more strenuous (calorie-expensive) the activity, the more likely you are to take rest days, which lowers your average daily caloric consumption.
Some levels of externalities are sustainable. Some are not. The larger problem with humans is the combination of total population and average per-capita resource consumption (to say nothing of the vastly higher consumption in industrialized nations).
The steel and rubber in a bike are probably the biggest concerns (as well as the paving in roads), but in comparison with an automobile, it's vastly lower, and in comparison with the ranges and cargo capacity of walking, they're hugely higher. I've travelled 200 miles in a day by bike, and commuted over 40 miles daily for over a year at one point. One person on a bike can move a payload of many hundreds of pounds, possibly a ton or more (across level ground).
Food production at present is manifestly unsustainable. Every one calorie of food you eat in the US takes 10 in fossil-fuel energy to produce (in Europe it's about 5). Other inputs, particularly nitrogen (from fossil fuels) and phosphorus (limited global supplies) are crucial limiting factors, as are topsoil and water.
Richard Manning's "The Oil We Eat" is a fascinating exploration of this aspect of human existence: http://www.wesjones.com/oilweeat.htm
2. Sustainability is what matters.
Does this activity add to the likelihood that humanity will cease to enjoy a standard of living similar to the current average at some point before other natural processes (Sun going red giant, etc.) kill us all anyway?
So hey, if they sun's gonna kill us all next year, go hog wild. If what I'm doing now means that somebody 500 years from now will have a more impoverished existence, it's not.
Advanced species lifespan seems to range from ~1 - 10 million years or so, plus or minus a lot, before genetic drift sets in.
Three hundred mega-years (what I meant) is a somewhat arbitrary milestone. (I think long-term but 10^15 years is a bit much for even me. But see Stapledon's "Star Maker"...)
(BTW, your thinking seems unusually clear on these matters.)
None of these are good, but we don't eat pandas, so which examples of habitat destruction are used is informative.
Yes, telegenic megafauna capture hearts, but really, as apex predators or other apex species, they're the canaries in the coal mine, so to speak (and my isn't that an unsustainable metaphor...). But the waste being laid to oceans: 80% depletion of fish stocks, mass strandings of numerous cetaceans, algae and jellyfish blooms, starfish wasting diseases, and the sudden disappearances of birds, seals, and sea lions, all suggest something is going very, very wrong.
And those systems are crucial for life on Earth -- human and otherwise.
I KNOW. But, difficult as it may be to believe, sustainability still isn't what I was talking about. And, no, that doesn't mean I believe it isn't a problem.
But here's the dilemma as I see it:
• Modern technological civilization is predicated on abundant cheap (high EROEI) energy sources. Technology follows from, rather than leads to, energy availability, and hence isn't an answer.
• For reasons of both depletion (peak oil / gas / coal) and pollution (greenhouse gasses, AGW, mercury and other emissions), continued use of fossil fuels isn't viable. We've already heat peak conventional liquids (oil), and global total peak oil production is likely within 5-15 years. Gas follows shortly after, coal likely by the late 21st / mid 22nd century assuming demand doesn't collapse entirely (which would generally indicate a collapse of civilization).
• If you want to continue a technological civilization of some sort, then you've got to find alternative high-grade forms of energy. Likely a mix of electrical generation (highly fungible) and limited liquid or solid fuels production (for transport and storage needs). Capacities to produce both are fairly constrained.
• The alternative is ... a non-technological level of civilization. Likely a collapse in both technological levels and population (from famine, disease, war, the usual). Which means that the future of humanity will be relying on solar power -- collected and stored by plants. And be living in a drastically depleted environment in which many ores and mineral resources, as well as water, topsoil, and ecosystems have been hugely depleted. "Rebooting" civilization would be at best very, very difficult.
• I like a technological civilization, don't get me wrong. But I don't see it as sustainable. And there's nothing in the laws of physics, chemistry, biology, ecology, or geology which say the Universe owes us our standard of living.
Answering your question about solar PV: the economics look difficult, and numerous people who are convinced of peak oil and climate change suggest that they may well not work, see Ted Trainer, John Michael Greer, Charles A.S. Hall, and Gail Tverberg among them:
"Renewable Energy: No Solution For Consumer Society" http://www.countercurrents.org/trainer240411.htm
But that doesn't exactly leave us with good alternatives, and my feeling is that PV or other high-grade solar technologies (solar thermal, Stirling or related engines) are worth pursuing with our remaining fossil fuel reserve (we really should have been pursuing these decades ago).
What's your alternative?
Enjoy your day.
Nuclear. I notice you don't mention this at all, unless you mean to include it in "electrical generation", in which case your statement that technological civilization is not sustainable strikes me as far too pessimistic. Even if you only consider nuclear to be a temporary energy source while we develop high-grade solar energy, it still can get us a lot further than our remaining fossil fuels.
Also, any evaluation of "sustainability" is fundamentally limited by our inability to predict how our society will change in the future. For example, a sustainability analysis done in the late 19th century, when horses were a primary mode of transportation, would have shown that that mode of transportation was not sustainable--we would have ended up, as the saying goes, knee deep in horses--t. Then the automobile came along.
In other words, there's a common confusion (as shown by many posts in this thread) between a specific way of doing things being unsustainable, and our society in general being unsustainable. It's far harder to show the latter than the former, because we can always change our way of doing things.
Great! Fission or fusion? What fuel cycle? What reactor design? Is it proven? Experimentally? Prototype? In production?
What's the fuel availability look like? How about issues with proliferation, waste disposal, plant accidents, and plant decommissioning?
I didn't spell out my alternatives in detail, but yes, nuclear is an option for electrical generation (I suppose you could also run a power loom or stamping gin off of one if you really wanted to). However of the options:
• Fusion's not there yet. Tokamak, NIF, or Polywell. Nothing but the shortest experimental possible ignitions yet. Nothing remotely commercializable. Several fuel cycles are fairly constrained.
• Uranium/plutonium LWR fission has a pretty critical fuel shortage. 80 years at present usage, 6 if we go 100% nuclear at present energy consumption rates. Scale in anticipated global energy growth rates and it's less than that. Waste, decommissioning, and accident issues are significant.
• Breeding uranium or plutonium might extend fuel supplies but creates significant weapons-grade material proliferation concerns.
• The TeraPower "nuclear candle" is a nice bridge technology ... if it works, but that only lasts until our existing nuclear waste is consumed (which raises the point: you don't want to be too good at disposal: the stuff might come in handy).
• Thorium has a vocal and occasionally demented lobby on the Intarwebs, but even the optimistic Chinese see MSR as 25 years out from commercialization.
And I see energy needs coming to a head Real Soon Now -- rather less than 25 years, at any rate.
And none of these technologies, nor wind, solar, geothermal, hydro, or tidal power give you liquid fuels, which is what planes, trains, automobiles, trucks, buses, boats, construction equipment, furnaces, generators, back-up power systems, and remote energy applications rely on. Sure, you've got Fischer-Tropsch, the Sabatier reaction, and other solid-to-liquid, gas-to-liquid, and fuel synthesis processes. All of which, scaled to the 100 million barrels of oil consumed daily globally would represent an absolutely massive investment of capital and energy.
Conventional crop biofuels, wastestream-to-energy, sewage-to-energy, and advanced algael biofuels all suffer from the challenge that your dealing with net captured flux of around 10 W/meter^2, maybe 100 W/meter^2 for algae, of photosynthetic efficiency. And you've got to capture that on land that's not already producing food you're planning on eating, or ecosystems you're planning on sustaining, you know, the rest of the Earth's biosystems.
The 100 quadrillion BTUs the USofA consumes annually corresponds to 29,307 TWh of energy, which at 10W/m^2 and 8 hours of effective insolation (a typical 30% duty cycle) means you're looking at 1,115,186 km^2 ... or a square 1056 km on a side (430,576 square miles, or 656 miles on a side, for the non-metric).
Sure, NYC of 1894 had 200,000 horses pumping out, literally, 5 million pounds of horseshit daily (https://ffbsccn.wordpress.com/2009/11/17/superfreakonomics-a...). And the straight estimates were accurate: keep that up and you'd be buried in the stuff (you already were knee deep in places).
Thing is: it's possible for things to get that bad. Ever been to India? Or just seen the opening sequence of Slumdog Millionaire? Because that's how a lot of people live: combing through trash heaps and swimming in shit (not equine, either).
And the reason NYC didn't drown in brown is because of this one-time lottery winnings of uncomposted Carboninferous lignan-laced pulp and algae decay which we've been talking about here (if decomposers had evolved slightly faster, we'd be discussing this in a small agrarian village somewhere). Technology, as I said, followed that windfall, it didn't create it (Colonel Drake's oil rig: borrowed from the Chinese who'd been drilling 1000 feet for salt since the year 1000). That rabbit's already been pulled from the hat, and we've been looking for a long time, pretty thoroughly, without finding many more rabbits for, oh, 40 years or so. The automobile didn't "come along", it was pumped from an oil well that's now running dry despite fracking fluids leaking into your water supply.
Technology doesn't create entropic gradients, it taps them. And we've got a pretty good idea of what provides useful energy: Moving stuff, falling stuff, blowing stuff, bright light, chemical bonds, and nuclear bonds. And it's mostly the bright light and chemicals that seem to work well for us, higher up it's not sufficiently dense or reliable, lower down and it's too complex. I don't see gradients (flows or stocks) we can tap with the ease and usefulness we have for the past 250 years.
Uranium/plutonium LWR fission has a pretty critical fuel shortage.
These numbers are way too pessimistic; they are produced by the same sort of calculations that said we would run out of oil by the turn of the millennium, because they didn't take into account the continuing discovery of new reserves. They also don't take into account breeders; if there are concerns about weapons-grade material being created, you guard the plant (the material doesn't need to be transported, it just stays at the reactor until it's used).
With nuclear fission there's an additional consideration as well: the cost of the fuel is only a percent or so of the total cost per kW-hr, whereas for fossil fuels it's something like 1/3 to 1/2 of the total cost per kW-hr. So it doesn't take a lot of increase in the price of oil to make fossil fuel electricity much more expensive; but even a large increase in the price of uranium doesn't increase the price of nuclear-generated electricity very much. And there's a lot of uranium that could be extracted at, say, 10 times the current unit cost; by some estimates we can extract uranium from seawater at that cost, which increases the time horizon to thousands of years if not more.
I see energy needs coming to a head Real Soon Now -- rather less than 25 years, at any rate.
Same comment as above: I think this is way too pessimistic.
none of these technologies, nor wind, solar, geothermal, hydro, or tidal power give you liquid fuels
Two comments here: first, improved battery technology; second, algae fuel.
that's how a lot of people live: combing through trash heaps and swimming in shit
We already have the technology to fix this; the reasons so many people don't (yet) benefit from that are political, not technical.
I don't see gradients (flows or stocks) we can tap with the ease and usefulness we have for the past 250 years.
Again, way too pessimistic. It's not that I don't see obstacles, but once again, the main ones I see are political, not technical.
Then cite your sources. The Wikipedia article I linked cites this MIT study for ~100 years supply at present rates of consumption: http://web.mit.edu/nuclearpower/pdf/nuclearpower-update2009....
I think this is way too pessimistic.
For liquid fuels I'd strongly suggest you check recent trends: BP's annual statistical review, CapEx spends and yields from Shell, BP, and Exxon, and projections from the EIA and IEA -- this isn't the Peaker fringe, by a long shot.
algae fuel
Tell me how much algae fuel you want and what conversion pathways (biodiesel, ethanol, synthesis, solids) you're referring to. Then give me acreages and water estimates. Oh, and how you're going to fertilize all that goop and keep pests out of it.
You've done some hand waves but I've seen no sources. Who or what do you rely on for information, estimates, models, or whatever else serves as the foundation for your optimism?
P. 12 of that study says "most commentators conclude that a half century of unimpeded growth is possible", and the study appears to agree with that assessment. "Unimpeded growth" means a large increase in consumption rate over the present.
Also, that assessment is based on a once-through fuel cycle and mining as the only uranium source. Over a half century to a century time scale the first assumption is almost certainly invalid (breeder technology is advancing) and the second may be shaky as well. (Note, btw, that a key reason why the MIT study assumed a once-through fuel cycle was not that breeders were not available, but that they were uneconomic at current uranium prices; but obviously if uranium gets scarcer, uranium prices go up and breeders become economically viable.)
Finally, a half century is not 25 years. If we have a half century to a century of nuclear power even with a once-through fuel cycle, we have an obvious alternative to fossil fuels for that time frame. Your claim that we will hit an energy crisis in 25 years assumes that there is no such alternative.
Tell me how much algae fuel you want and what conversion pathways (biodiesel, ethanol, synthesis, solids) you're referring to. Then give me acreages and water estimates. Oh, and how you're going to fertilize all that goop and keep pests out of it.
All of which are issues that are going to be solved, if they're not solved already, probably well within your 25 years, certainly within a half century. Google turns up plenty of hits on "algae fuel" or "algae fuel study" that show plenty of progress in this area.
the foundation for your optimism
Human ingenuity plus profit motive plus an obvious market for cleaner forms of energy. What I noted above with regard to the assessment of breeders being viable is true more generally: a key limitation of most assessments of available energy resources is that they only look at what's economical given current prices, not what's possible. But the economics will change.
That's not to say that there are no obstacles; but as I said before, the main obstacles I see are political, not technical.
Um. No. First, the term isn't defined or clarified, so you're simply applying an interpretation convenient to you. On page 3 you'll find growth assumptions clearly stated:
[T]he study explicitly assessed the challenges of a scenario in which nuclear power capacity expands from approximately 100 GWe in the United States in 2000 to 300 GWe at mid-century (from 340 to 1000 GWe globally), thereby enabling an increase in nuclear power's approximately 20% share of U.S. electricity generation to about 30% (from 16% to 20% globally).
That is the growth which can occur unimpeded for up to 50 years.
You've also conveniently failed acknowledge the first half of that sentence, given in full here with the pargraph it occurs in:
Table 2 shows Red Book identified resources, undiscovered resources, and the number of reactor years of fuel provided by those resources. Based on the total projected Red Book resources recoverable at a cost less than $130/kg (2006$) of about 13 million metric tons (hence about an 80 year supply for 800 reactors), most commentators conclude that a half century of unimpeded growth is possible, especially since resources costing several hundred dollars per kilogram (not estimated in the Red Book) would also be economically usable.
We're still left with 80 years supply for 800 1 GWe reactors. Better than the near-term critical situation for liquid fuels, but hardly copiously abundant.
On Algae:
All of which are issues that are going to be solved
Yeah. So, Boeing's just released "the biggest breakthrough that there is out there" in biofuels, those are its director of sustainable aviation fuels, Darrin Morgan's words, not mine. Halophyte (pickleweed) farming integrated with aquaculture for aviation fuel production at ~75 gallons/acre-year. Aviation fuel is around 5% of total US oil consumption (15,998 million gallons in 2013, RITA), roughly 1 million of the 20 million barrels of oil consumed daily in the US.
Supplying just 5% of US oil consumption from pickleweed would require 21.3 million acres under cultivation. That's about 330,000 mile^2, or a region 577 miles on a side. You could start in Shreveport, LA, and drive all the way around Oklahoma and Kansas without ever entering them. Boeing's article mentions having "thousands and thousands of hectares* under cultivation. How about millions and millions?
http://www.reddit.com/r/dredmorbius/comments/1wo2hl/boeings_...
Algae are, typically, about 10x more productive than plants, but present their own host of challenges (infrastructure and capital requirements, disease, water, fertilizer, waste removal, plumbing issues). Since the above calculations are for a 5% replacement of petroleum, you could take the same acreage and say instead you're getting 50% of present oil usage. Realize that those 21.3 million acres _now all have to be constructed_ with pumps, drainage, etc. And somehow supplied with water. And placed somewhere that they don't interfere with existing food, habitation, and essential ecosystems.
Good luck with that.
Human ingenuity
Can you demonstrate a single case in which human ingenuity has created a new entropic gradient to exploit, rather than found an existing one? What existing gradients can you point to that we can tap? We've covered nuclear and biofuels here. I see solar, wind, geothermal, hydro, and tide/wave left.
I'm not sure those two quotes are talking about the same thing. I notice that different numbers are quoted in different statements in the document; for example, on p. 12 there is this statement:
This reinforces the observation in the 2003 MIT study that “We believe that the world-wide supply of uranium ore is sufficient to fuel the deployment of 1000 reactors over the next half century.”
Which is different from the "80 years for 800 reactors" statement.
But more importantly, you're ignoring additional information that's given in the same sentence we've been quoting and the one immediately following it. You expanded the quote to give the first half of the sentence, but you conveniently ignored the last part of the sentence, which I'll repeat: especially since resources costing several hundred dollars per kilogram (not estimated in the Red Book) would also be economically usable. I.e., the "80 years for 800 reactors" figure (and by implication the "1000 reactors over the next half century" figure) does not include all estimated resources. The very next sentence is:
Using a probabilistic resources versus cost model to extend Red Book data, we estimate an order of magnitude larger resources at a tolerable doubling of prices.
I.e., at twice the current uranium price (which, as I noted before, would mean only a small increase in the price of nuclear electricity to the end user, unlike fossil fuels where fuel cost is a major factor in end user price), we have 10 times as much available, meaning 80 years for 8000 reactors, or 10,000 reactors over the next half century. That's a big difference. And since uranium prices will certainly go up if it becomes scarcer, there will be natural economic forces driving people to tap the 10 times as much uranium that's available at higher prices. So you are conveniently failing to acknowledge information that's in the document you linked to. (And that's still leaving out breeders, which as I noted before, were left out of the MIT study for economic reasons, not technical reasons, and as uranium prices go up the economics change.)
those 21.3 million acres
Or about 23 percent of the area currently under cultivation in the U.S. (922 million acres according to Wikipedia). But we're talking about 25 to 50 years, not right now. There's no reason why algae acres have to displace current farm acres on that time scale. That 21.3 million acres is about 9 percent of the land area of the U.S, which is significant but doable. Or, if we wanted to get creative, we could put the algae farms on platforms offshore and out of the way (and with easy access to fresh water using desalinization rigs--or even using salt-water tolerant algae).
Good luck with that.
In the next 25 to 50 years, the items you list are easily doable. That's not to say they'll actually be done; but once again, the main obstacles I see are political, not technical. I notice you haven't commented on that at all.
Can you demonstrate a single case in which human ingenuity has created a new entropic gradient to exploit, rather than found an existing one?
Of course not; that would violate the second law of thermodynamics.
What existing gradients can you point to that we can tap?
Here on Earth, for the near future, you've covered all the significant ones I'm aware of (assuming solar includes solar thermal as well as photovoltaic; I haven't seen a lot lately on solar thermal, but it seems like an obvious alternative worth pursuing).
Mind: the minimum feasible grade for extracting energy-positive uranium is around 0.02% grade (http://www.stormsmith.nl/i05.html)
Generally: http://en.wikipedia.org/wiki/Peak_uranium
Meanwhile there are just as many optimistic predictions that it will last for thousands of years, if not longer. What makes you so sure it's only 80/6?
I have lived for many years within the energy budget provided by photovoltaics and the wind. It is possible to live well under such circumstances, and to be as technological as a city dweller, but first you have to eliminate the waste.
Take, for example, your houses and apartment buildings. They are so poorly constructed that the planet would be considerably better off, despite the waste, if we tore down every single last one of them and rebuilt them for longevity and energy efficiency.
A few buildings (maybe three in a city of 5 million people) are constructed well. They use (at the moment) ICF techniques and they are so well insulated that, even in the coldest days of January, the heating system can fail completely for over three days BEFORE ANYONE NOTICES that it is broken. They can use geothermal heating exclusively both winter and summer and provide complete comfort for 10% of the normal cost.
But you do not build your stuctures like this because energy efficiency is not a priority; money is the priority. The scumbag builders build shit buildings to maximize their profits; the scumbag realtors sell units to the ignorant masses for a fortune, and nothing changes.
What is wrong with humanity is that we are just too fucking stupid and far too much in love with ourselves to do the reasonable thing. We are crazy for money and it has become the arbiter of all success. Instead of killing off 90% of the species, we could begin by simply eliminating the 90% of our activity that is wilfully wasted and continue to live well, so long as the reduction in resource usage was not simply an excuse to increase our already ridiculous numbers.
So that is my alternative: stop being monsters. Otherwise I cast my vote for us all to die of a virus incubated in the backstreets of Shenzhen, and good riddance.
110, OK, here your point makes some sense. But what about when living to the fullest costs "850+ externality"? (e.g. compare mean oil consumption per capita US vs China).
If we're going to use this argument, at least let's be honest about it: we are not at 110, and our motility is not the problem.
You can work yourself into knots over it; there is no way in which you can eat food and not have some negative impact. So, IMO, you either give up the battle entirely, or you can stop killing yourself over it but still make intelligent choices. For example, I eat fish because I believe fish farming could be a better choice for the future than cattle farming, and I eat chicken because the feed-to-meat ratio is better than beef.
As not only animals but meat-eating animals, it's just a fact of life that our/your existence costs something, means some sort of sacrifice for another organisim. You can try to reduce your impact, but you can't not have an impact.
Also, a little bit of my personal philosophy here- one way we could reduce our impact is by doing as little as possible, never moving about and burning more calories than absolutely necessary. Never performing strenuous activity that results in regenerative & anabolic processes, which require extra nutrients. But the way I see it, just existing costs the world "100 externality". If living to the fullest costs "110 externality", I feel like I am doing a disservice if I chose the first option, saving so little "externality" and spending my life miserable. For have I not then utterly wasted the costs I imposed on the world?