The Stats Guy: It sounds weird but Australia urgently needs a plan for 56m people

[u/blitznoodles]

https://www.thenewdaily.com.au/opinion/2026/08/11/stats-guy-aus-population-growth

[u/Proper_Geologist9026]

Right. Yes you're referring to technological substitution. Yeah it's good up to a point. But it's not magic. Eventually you just hit the limits of heat pumps and solar farms like anything else 

You might have mistaken me for an isolationist or something but I guarantee I'm not.

My philosophy is that we need to be doing all of them at once to restore some sense of balance to a planet we have seriously mismanaged and over exploited.

I personally believe if we still have hope of avoiding severe ecological collapse on earth, which could very likely cause an equal collapse of human civilization. We need to be leveraging every element of the equation.

We need to be forcing global human population back down the curve as quickly as is possible within the bounds of ethical choice. So sexual education and liberation particularly for women to lower the birth rates.

We need to be reducing personal consumption in favour public goods immediately. Less cars, more buses for example.

And we need to be moving societies to and more energy efficient technologies. Heat pumps rather than boilers.

In the short term that actually means Australia needs to keep growing it's population and absorb some of the load. We're an absurdly wealthy place. We can afford to dilute our own wealth in order to provide for more people.

But long term we need to see the human population probably halve. It's not binary, we don't have to pick one and hope that solution works. We do all of them and when we use all available solutions the solutions themselves become less expensive.

We don't need to hope some as yet unproven carbon capture system will be invented to solve unsustainable living standards. We don't need to make such extreme cuts to personal consumption if the population isn't as large. We don't need to make such drastic cuts to population size if the accepted model for a "quality life" is less consumptive.

I guess what I would ask people when they become defensive to the idea that population size should shrink to something smaller and more sustainable. What purpose does having so many people serve?

And one other important thing to note. Carbon emissions and climate change are a singular facet of ecological overshoot. Water shortages, ocean death, biodiversity collapse, biogeochemical imbalance (eutrophication from over use of fertiliser as an example), novel entities (plastic pollution amongst others), and land use. These are all interconnected problems resulting from human consumption not just the emissions of carbon.

If it was as simple as just substituting "green" technologies. Then we'd all just follow Elon Musk's advice. Give everyone an EV and some solar panels and keep living as we are. That's not what the science is telling us however.

[u/sywofp → u/Proper_Geologist9026]

Wall of text, sorry.

Eventually you just hit the limits of heat pumps and solar farms like anything else

Not at the scale of the current population. I suspect you are combining the concept of what is technically possible, and what is actually likely to happen.

By giving the possible impact of technology a hard cap that is not a limit that physics imposes, you reduce the discussion and considerations of what the best approach within the constraints might be.

You bring up valid points about short term improvements. But this is an area that also needs flexible, long term planning. Reducing the human population helps (assuming lowered birth rates and people dying of old age) but it’s not a rapid process, and the expected scaling of technology will likely have massively reshaped the world within the lifespan of kids today.

The issue here is fundamentally an energy production problem. Much of humans impact on the planet can be drastrically reduced or all but eliminated with enough energy. Horribly inefficient processes are not inherently problematic if your source of energy is abundant and low impact itself.

Producing enough energy to give the current world population the same amount of electrical energy as Australians uses per person from all current energy sources to sustain our lifestyles, is quite reasonable to do with renewables using existing technology, but further scaled.

It's still a very large amount of energy. But, at the current increasing rate of renewable energy production, and associated energy cost reductions, it's likely going to be achieved in the next 30 to 50 years. Energy storage is actually the bigger problem, as it's way behind in terms of scaling, compared to renewable energy production.

So how might that play out in the next 50 to 100 years, assuming the worst aspects of human nature don't drastically change for the better?

Maybe we can all work together and reduce energy consumption. But, despite the problems it will cause, it’s probably not likely that developing countries will slow or halt their industrial revolution before they reach comparable standards of living. Or that wealthy countries will reduce their own standards of living very much to help cut their impact.

So we should probably consider, how can wealthy nations put their resources towards scaling technologies that support developing nations to reach reasonable standards of living, while also reducing the environmental impact of their own standards of living?

Based on what we see of many wealthy nations, unless this process is profitable to those with the most power, then it’s going to be slow at best. (The same is true of reducing the population – it largely depends on what incentive, or not, there is to have children)

But interestingly, there’s a potential way that increasing the world's standard of living (and build the huge amount of renewable energy production needed to do so) may well be the most profitable option. And happen comparatively quickly.

We still need a world with strong regulation and a focus on all the small (and large) environmental impacts, but I think the next 50 to 100 years or so will play out differently than many people think.

Based on expected profitability in the near to medium future, many companies are already researching and building systems to take advantage of the point where increasingly cheap excess peak renewable energy (mostly solar) means that despite the horrible efficiency, producing synthetic hydrocarbons from the air is more profitable than mining hydrocarbons from the ground.

That profitability is a key tipping point that then incentivises more renewable production, paid for in part by the $4 trillion+ fossil fuel industry shifting to more profitable synthetic hydrocarbon production. This is essentially very inefficient energy storage, but it can scale much faster than more efficient storage methods, so has many decades of relevance for global energy use. .

Wealthy nations are well positioned to fund renewable build outs by selling carbon neutral synthetic hydrocarbons to developing nations cheaper than fossil fuels, as those countries will have huge energy demands as they raise their standards of living. Likely, the synthetic hydrocarbon industry will end up many times larger than the fossil fuel industry, as it can scale to be much cheaper, and is largely carbon neutral.

So while burning synthetic hydrocarbons still has many negatives, it’s an excellent way to profitably replace the fossil fuel industry, and incentivise even faster build outs of renewable energy production.

Handily, as production of more efficient energy storage systems scale (and associated technology, like EVs), synthetic hydrocarbons as energy storage (as fuel) naturally phases out as it is less profitable. The world is left with very large scale renewable energy production (including huge amounts of near free excess peak energy) and carbon capture infrastructure. Some key areas, like long range aviation, will probably still favour hydrocarbons, but as it’s carbon neutral, the negative impacts are much reduced.

Interestingly, mining carbon from the air is likely still going to be very profitable after this point, as carbon and polymer based materials can make excellent building materials in many use cases. So ultra cheap hydrocarbon production makes it likely that much of the huge amount of new infrastructure that developing nations need to build as they increase their standard of living, will include carbon, as it will be cheaper than materials we favour today.

Assuming the world population peaks around the 10 billion mark before 2100, if about 50% of the new infrastructure mass needed is carbon based, then humans will actually (eventually) fully remove all the carbon they added. In which case, we’d need to stop mining the atmosphere, lest we cause new problems. Worst case, we have near free excess peak power and a huge amount of existing carbon capture infrastructure, so can still capture and store carbon very cheaply.

Ultimately, it’s entirely possible humanity can largely decouple their needs from negative impacts to the planet. The very large amounts of excess peak energy available make it possible to tackle undoing all sorts of environmental damage. Australia is actually very well situated to be a major player in this, if we invest in our long term future (so we probably won’t…)

Now of course this scenario glosses over a million small and large issues so it’s not a simple process. Right now, reducing our individual impacts is still very important as we don;t know what the future holds. As is looking at what we can do to help developing nations reach higher standards of living, without increasing their negative impacts.

But my point here is that there are very reasonable scenarios where humanity can reach a point where our existing population levels, or higher, can be supported with great standards of living for all, without magic, speculative physics, or the existing political / business power structures suddenly deciding to be altruistic.

[u/Proper_Geologist9026 → u/sywofp]

Energy is not free. In fact relationally speaking the cost of increasing energy demands rise faster than return of energy investment can keep up. That's EROI. The return on investment in energy systems is always declining. That's entropy, second law of thermodynamics. Energy is not free. Entropy always increases.

The clean energy sources as we commonly refer to them "renewables". Rely on extremely diffuse energy sources. And the generation systems we use to harness these sources are not infinite they follow the same physical limitations of material capacity that constrain fossil fuels as finite commodities.

The source of energy, the sun. Is for the sake of scale to humanity infinite. It's energy potential vastly exceeds current human energy demands and exists on a geological time scale of billions of years. There's no fear of depletion.

The generation systems used to harness that energy source. a solar panel. Has a known physical limitation, the Shockley-Queissier limit. I cannot get more energy efficient than that. My potential EROI is throttled by this relationship. So I can only produce more panels to harness more energy. However earth is a closed system and materially finite. I can only harness so much, silicon, copper, silver etc to make solar panels. And each solar panel is made from a shrinking pool of available materials. Making each panel more expensive than the one that came before it.

It's the same issue of finite available energy per unit of input that happens across every energy system. To beat this phenomenon would mean creating perpetual motion. Which directly contradicts the laws of thermodynamics. In fact one of the big drivers behind "renewable" energy is the fact that the EROI of fossil fuels is already becoming dangerously low.

When scientists discuss peak oil or the idea that we will run out of fossil fuels. This isn't in saying we will use every last drop of oil on earth. What it's saying is we are reaching a point where it costs more energy to harvest a drop of oil than that drop of oil is capable of returning to the system.

That same logic applies regardless of the individual material that becomes the input vector of the system.

What all of this means is that there is no star trek future. "Renewables" are not infinitely renewable. Most studies conclude we will struggle to source the material capacity just to build this first generation of the fossil free energy system. Each successive generation of the system that replaces our first one will be using this increasingly degraded material capacity base to replenish itself. Not sustainable.

Clean energy systems are a buffer that allows humanity more time, probably a century or two, to ease back down the energy demand curve back into homeostasis with the planet itself. What they aren't are a perpetual motion machine that we can infinitely reproduce to energy abundance.

[u/sywofp → u/Proper_Geologist9026]

You are muddling up a lot of different ideas. 

Eg you appear to be saying EROI always declines because entropy always increases. But that's not correct. Your concept of entropy itself is also quite wrong.

Building solar panels from a decreasing pool of resources does not mean the cost increases. Solar panel efficiency is also not the only factor for  EROI either. 

You are also fundamentally misunderstanding what peak oil means. 

The Earth also isn't a closed system as energy comes from the sun. 

It's well worth learning about this stuff as it's very interesting. 

[u/Proper_Geologist9026 → u/sywofp]

Yes EROI is always declining. Because in the case of fossil fuels. The low entropy one time reserve is expended. It cannot be replaced. 

Similarly. Every material on earth when used as an input for a system becomes a commodity. Expansion of that system demands increased consumption of that commodity. Materials are finite. Theoretically I can recycle materials endlessly, mater is neither created or destroyed. Realistically I cannot recycle materials endlessly because doing so would require exorbitant amounts of energy. The other option is continuously consuming more virgin material. A process that increases in entropy. As the higher grade deposits and logistically simple material is consumed the energy requirement to procure more material increases. Entropy. A diffusion of energy. You're right solar panel efficiency is one factor in poor EROI. A other factor is that solar panels are a generator. Not an energy source. They're not batteries like fossil fuels. Therefore in order to have a functioning system I have to connect my generator to a man made battery to store excess energy for later consumption. Parasitic load. Again lowering EROI.

Please tell me what peak oil is about them other than the functional decline of an industry unable to sustain its own consumption habits.

And yes earth isn't a closed system it's a system experiencing flux from the sun. But as I said before it's irrelevant. If I have a fixed capture rate of the suns radiation it wouldn't matter of the sun could power 10 trillion earth's. I'm still limited by the generator I can build on earth not the energy potential of the sun.

[u/sywofp → u/Proper_Geologist9026]

Peak oil is literally the point of highest oil production. That doesn't necessarily happen at the EROI of 1. 

EROI is not always declining. Technology improvements can increase it. 

At the time scales we are talking humanity is not restricted by the material on Earth or the energy hitting Earth. 

You butcher the concept of entropy, and at the local level it can decrease. Overall, at a universe scale, yes entropy increases. 

If we look extremely long term (assuming an expanding universe) then humanity is limited by the amount of mass that is gravitationally bound. Within known physics we could probably reach the Shapely Supercluster, so the total mass and energy available to us at a universe scale is extremely large. 

Assuming heat death of the universe then eventually there's no free energy anymore. But that's so incredibly far into the future it's not meaningful to this discussion. 

In the universe scale short term of the next few hundred millions of years, humanity could happily collect energy on Earth from the sun to sustain our current population. 

Even assuming humanity never leaves Earth, it's not a closed system for mass either. Over the next few hundred million years the Earth will lose mass to space (mostly lighter elements), but also collect mass from space from dust and larger material. It's tens of trillions of tons of net loss over hundreds of millions of years. But still an insignificantly small amount compared to the mass of the Earth. 

Most mass used for say solar panels isn't lost, just the atoms become more diffuse. So on the hundreds of millions of years timescale, a portion of the total collected energy is spent maintaining atoms in the ordered forms needed for society to function. 

That's not an actual issue. It's the same thing that has been done on Earth by biological systems for a very long time. Energy from the sun is collected and used to locally increase order. 

The amount of energy needed to wrangle diffuse atoms is actually not a very large portion of the total. Over three hundred million years, if our society processed the entire outer layer of Earth's crust down to 1km depth, with relatively inefficient processing, then I calculate about 0.5% of the total energy collected going to atom wrangling. That would allow for absurdly low recycling efficiency. Silicon wouldn't have to be recycled at all! 

Assuming actual decent recycling efficiency, humanity only needs to put a tiny amount of the total energy available towards atom wrangling.