Plants produce oxygen during the day, but they absorb it at night.  If you have too many plants, some will block out light for the others, and they won't produce as much oxygen during the day.  But at night, all the plants absorb oxygen, and the fish will suffocate.  It can be very sudden. You just wake up in the morning, and the fish are all gasping at the surface, or dead.

Plants can also screw up the pH of an aquarium by absorbing CO2. (This is why those who are really into planted tanks use CO2 injection systems.)  Fish can adapt better to pH changes than most people think, but a brightly-lit aquarium without enough CO2 can suffer pH swings that are fatal to fish.  

"I don't anyone here doubts that wind & solar have excellent EROEI"

If, so, that's great.  I've not been sure that we had a consensus on that.  

"I believe the more relevant question is how much of that energy can we harness and how quickly can we harness it?

Well, I agree that's important too.

"As Savinar accurately notes, a 10% reduction in our oil energy usage would result in a need for a 2,200% increase in wind and solar growth.  "

I assume what you mean is that wind and solar would have to be 22 times larger than they are now to replace 10% of our oil usage.

First, that's incorrect. We could replace 60% of oil by replacing gasoline personal transportation with electrical.  That would require a roughly 15% increase in electrical usage.  As wind alone will produce about .9% of US electricity by the end of 2006, that's a 1700% increase in wind to replace 60% of our oil.

Second, they're very roughly doubling every two years in the US (40% growth rate per year).  That means in 10 years you would get 5 doublings, or 32 times as much.  

Actually, we have plenty of coal for electricity for the transition (if you ignore GW, of course), the much bigger problem is accelerating the conversion to electrical transportation.  We're roughly at .6% electrical for personal transportation new sales (1.7% of light duty vehicle are electric-gas hybrids, and they're roughly 1/3 electrical - yes I know their power source is 100% gas, but the powertrain is what I'm focusing on) now, so we have (ahem!) a little ways to go.  That's the big problem, not renewable energy supplies.

Of course, we reduced gas usage in 79-83 by 7%just with driving better, and switching to smaller cars, and overall oil usage by 16% (because businesses are more sensitive to energy prices than consumers), and ethanol will help a bit (it's likely to contribute at least 3% in the next 5 years, even with it's current excessive nat gas consumption problem), so we can likely muddle through a 10% drop.  

"the United States supply could fall much faster than the projected 5% decline rate even backed by CERA."  Well, I don't think CERA has backed 5% anytime soon.  But, I agree that depletion could be higher than that.  That would be mighty painful.  I don't see collapse, but I suspect  5% would stop economic growth, and higher would cause recession/depression.  No question, we have serious risks here.

"A large gain in the price of fossil fuels would result in the mining and processing of silicon becoming more expensive"

It would raise costs a bit.  Silicon is astonishingly plentiful (think sand), so mining is easy. Melting into PV grade purity takes a fair amount of energy - it's by far the lion's share of the energy input for PV.  Still, the energy required is dropping very quickly, and ultimately the high E-ROI of PV means than the output of PV would be that much more valuable.

"--not to mention the huge demand on silicon causing price to rise greatly."

It already has, to ration supplies.  That's mainly why prices of PV have risen in the last couple years: silicon supplies have been rising by 10% per year, while demand has been rising by about 65% per year.  It's an investment lag, which will be mostly fixed in a couple of years: the silicon supplies are expanding like mad.  Of course, PV producers are reducing the thickness of their PV wafers like mad too, which is the main reason they've been able to keep production rising at 40%.  That's why energy required to make PV has been dropping rapidly, as noted above.

Finally, you ask if spiking energy costs will raise labor costs. Sure, but the increase is a small % of the increase in energy costs. The CPI has risen about 6% total in the last 2 years, while oil prices have roughly doubled.  Everything may need oil now (mainly for transportation), but the oil is only 40% of the US's energy, and a much smaller % of business costs.

Actually, if oil tripled it would mainly put us into recession rather than raise inflation, as the Fed would raise rates sufficiently to keep inflation low.  That would keep labor costs stable.  Interestingly there would be an enormous amount of cash going to oil states, which would likely go in part to investment funds which would channel it indirectly into energy investments like renewables.  Why would oil-states invest in renewables?  Well, they wouldn't, but there would be so much cash floating around looking for a home that even if they consciously avoided funding their competitors, their money would displace other funds which would go to energy investments.  Short term rates, those controlled by the fed, would rise, and long-term rates would fall, encouraging long-term investments.  We're already seeing this, as the "rate-curve" inverts.
Already venture capital funding has doubled this year from last into energy, to about $1B I believe.

Replacing heavy truck shipments with electrified rail shipments gives a direct ~20 to 1 savings.

Going from an "average" commuter car/SUV to electric Urban Rail gives ~6 to 1 direct savings.  Changes in the urban form multiple that with indirect savings that get close to 20 to 1.

http://www.lightrailnow.org/features/f_lrt_2006-05a.htm

(joule instead of BTU for the metric)

My opinion has always been that with very aggressive government leadership the US could/can begin cutting total energy consumption immediately. It would involve a bottom-up restructuring of our economy and total redefinition of incentives.

If Westexas's argument about the availability of oil-for-export is correct (and I find it convincing), then a barrel of oil is going to be very freaking expensive from now on. Nothing I've seen about CTL or unconventional oil has changed my veiw that crude is headed well into the hundreds (and "not the low hundreds" as both Simmons and Jim Rogers have quotably phrased it.) It's a scenario that will play out certainly within the next 5 yrs.

Huge portions of our economic infrastructure are simply incompatible with petroleum being that expensive. Which will cause huge economic dislocation -- on scale that has historically sent societies into chaos. I've been reading Columbia econ professor Nouriel Roubini recently, who says much about the massive systemic risks of the housing bubble. It's a very convincing case.

Now, when I think about the likelihood of societal collapse, my first question is whether our civilization is capable of that sort of massive readjustment. Personally, I don't think it is. The much more likely scenario (to my mind) is one along the lines of Orwell's 1984 -- a repressive and propagandistic political system governing a resource-poor society (people cold, facing chronic shortages, etc.)

People always have noted that Orwell got that wrong -- I think he might actually have gotten it right.

If not probable, I do think it's possible that we can clear the energy bottleneck, and still remain intact as a society (if not a rich, liberal democracy as we've come to define ourselves in that past century or two.)

But the brick wall in my extensive reading is the one that James Lovelock's throws up. This, of course, is the guy who figured out how the planet works as a system -- simply a remarkable piece of scientific insight.

He gives us 0% odds of surviving the next century. Sees global warming has already entered runaway mode. Best we can do in his view is enjoy the next 30 years or so before things start to get truly catastrophic. Most of the globe will be uninhabitable by 2100. Life will be eked out near the poles in his view.

With stories like this creeping into the press, it's hard not be swayed:
http://www.nzherald.co.nz/section/story.cfm?c_id=2&ObjectID=10392615
http://www.sfgate.com/cgi-bin/article.cgi?file=/c/a/2006/07/06/MNGSPJQ8221.DTL

Then of course there are all the other feedback loops: methane hydrates are now thawing in the pacific; the world's largest bog is thawing in Siberia (containing serious quantities of methane, etc etc etc)

The fallacy in our popular debate is that somehow we start driving hybrid cars and putting up wind farms that these mechanisms wont continue (and continue to accelerate) for decades and centuries. Basically, it seems like we need some as-yet-unfathomed technology for planetary engineering or we pretty much know (even if we pretend not to) the trajectory that this is all taking.

Lovelock is more of straigh shooter than many climate scientists who are incredibly timorous about what they say or pointing out both the first and second derivatives of most measures of climate change are positive.

If you're serious about these questions, you really have to start with Lovelock and consider what's realistic after that.

I hope to hell he's wrong, but I don't see that being the case.

Now you have to explain how the Sun is gonna get 22 times bigger. Finish your beer-pong game. I was just kidding. I know  a 10% reduction would result in a whole bunch of different things.

It appeals to a basic human emotion:
our own memory of how we "grew up"
to be of a "just right" height in our personal life.

We tend to think in linear terms because of our shared experience regarding personal growth. It seems to validate the notion that "people really do "get enough" of things that they need" (quoting Nick).

But we are not talking about individual people here. We are talking about population, about a mathematical concept that gets hidden into complex census and demographic numerologies. Yes, we can look at graphs of exponential growth functions (y=e^kx) and say to ourselves, "I get it". But then again, seeing is believing. We believe what we see in our everyday life. We believe that plants, people, etc. grow slowly and controllably over long periods of time. We tend to disbelieve concepts that are not validated by our everyday experiences. There lies our problem, our own lying eyes. We dont' truly grasp the exponential function. We don't truly believe that we are already rolling down that short takeoff runway to hell.

No matter how many times Dr. Bartlett's video lecture has been replayed here at TOD and elsewhere --it needs to be replayed in our heads, again and again just to counter our lying eye notion that people get what they need even though they may not get what they want. It is simply not true that all people get what they need. Ask the floating corpses of NOLA. They'll tell you! (Well maybe not. They're dead.)

For more info on Doc Bart's essays, click on his photo to the right. Also click here.  

This is difficult, emotional stuff, but I think we're making progress.

• World population growthis clearly leveling off
  
• My main point is that population growth is slowing down dramatically
  
• In the human case reproduction, fertility and pop growth have declined in an orderly fashion
  

• now we're wandering into areas where I'm not thoroughly informed, so I can only offer bits of info that are suggestive.
  
• "Have you read the latest version of "Limits to Growth" yet? "
  No, I'd like to.
  
• The rest, especially water, I haven't researched yet.
  

Thank you, that's exactly what I'm saying.   It is certainly possible that we've gone off the cliff.  What I'm arguing about is a narrower point: that pop growth is currently slowing down, and that it is doing so not because of hitting a wall, but because of affluence.

Why is this important?  Because it influences our perspective.  If we recognize that pop growth is stabilizing because of human ingenuity, not because of resource constraints, we recognize that...we are not yeast.  We have a great ability to adapt and improve.  Again, not a reason for complacency - exactly the opposite - just a reason not to dismiss our ability to cope with the adversity which is coming.

On depletion of clean, freshwater - yes, I agree that it's clearly an enormous problem, especially for developing countries, which I haven't researched yet.

On energy I disagree.  Clearly in the longterm there's enough energy from renewables.  The transition will be painful - how painful depends on a lot of things, some of them unknown, like the depletion rate.   At the worst it could be a major depression.  But, a transitional problem is not the same as overshoot.

Now, could a transitional problem overstress our society to collapse?  It's certainly conceivable - nuclear war and nuclear winter would do it.  We still have the weapons.  I was fairly optimistic about our ability to avoid completely irrational war until GWB took us into Iraq.  Now....I'm not quite as optimistic.

Still, when the people who argue for collapse say things which are divorced from reality, like that pop growth is out of control, that if it is stabilizing that it's only because we've hit the wall, or that replacing oil is just flatly impossible, I can be confident that they are not completely informed in general and relying on bad sources like Kunstler.  If they hold fast to those ideas in the face of evidence to the contrary, then I surmise that that they: 1) are willing to exaggerate becaue they think that's the only way to get people to move on the serious problems facing us, or 2) saying it more out of an pessimistic instinct than from the evidence, or 3) are motivated to believe it by a primitivistic impulse and/or the misguided idea that people can be made less materialistic by making them poor.

Really?  I thought washing more than once per month was considered very weird until the 20th century.  I'm told perfume was invented for this reason...

"Peak firewood?"

I understand that the royal forests, like Sherwood in Robin Hood, were royal preserves precisely because of peak wood...

The idea that "we" (on planet earth) are in overshoot is based on an average across nations with vastly different population densities.

I think the world would be a nicer place (from my perspective) if human birth rate had naturally fallen 100 years ago, but the whole idea of declaring "overshoot" is in some dangerous sense ... optimistic.  It may be even worse than that.  The planet may support a whole lot more of "us," without crashing, but with continued mass extinction in the non-human biosphere.

On the rest of the literature: I agree, it there's a lot out there that would be good to find out about, and it's frustrating to try to discuss it without a deep background.  It's tough to become an expert on all this stuff. I suppose I should resist the temptation to comment when I don't have the details, the way most people do on TOD (though I try to make clear the limits of my comments, which a lot of readers don't seem to read carefully enough).  OTOH, I have to say that it's very clear that a lot of people are more pessimistic on energy than they should be, which suggests to me that a lot of the pessimisim in other areas might be similarly unwarranted.

On human nature, please see my earlier reply.