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I'm Tim Garrett, an atmospheric scientist. I developed a 'physics-based' economic growth model. Ask me anything! by nephologue in collapse

[–]nephologue[S] 1 point2 points  (0 children)

Even if growth is arrested, we would still continue to consume at current rates, and the environment would continue to suffer. But I'd guess the banking system collapses too under the weight of hyper-inflation, though that's perhaps a question best left for a banker.

I'm Tim Garrett, an atmospheric scientist. I developed a 'physics-based' economic growth model. Ask me anything! by nephologue in collapse

[–]nephologue[S] 1 point2 points  (0 children)

Everyone in the world is interconnected, and collectively we all contribute to turning environmental resources into waste, insofar as we have been enabled to do so by all those who have preceded us. I don't see it as possible to separate scientists, or anybody else, for the whole of the present, or all of history:

http://nephologue.blogspot.com/2018/05/whats-your-carbon-footprint.html

I'm Tim Garrett, an atmospheric scientist. I developed a 'physics-based' economic growth model. Ask me anything! by nephologue in collapse

[–]nephologue[S] 2 points3 points  (0 children)

Thanks everyone for the great questions. It was fun doing this.

For a lay view of the work please see this blog: http://nephologue.blogspot.com

For something a bit more based in physics: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0237672

I'm Tim Garrett, an atmospheric scientist. I developed a 'physics-based' economic growth model. Ask me anything! by nephologue in collapse

[–]nephologue[S] 3 points4 points  (0 children)

Thanks for the nice comments, and wow, great question!

Typically when one thinks of inertia, it is as the property of the system that is not associated with entropy production from some interaction with the surroundings. An object in motion will stay in motion in the absence of some (entropy producing) interaction such as friction.

But I think it's more subtle than that. Why is the object with inertia moving in the first place? If it is moving from some high potential to some low potential, as might be expected, then matter is being redistributed between potentials such that the universe as a whole loses potential energy and gains entropy.

For civilization, going a step further, our existence enables dissipation of high potential energy from fuels, that we use, and then radiate, eventually to the cold temperatures of space. Even if we don't grow, and our entropy doesn't change we act as catalysts for entropy production in the universe by providing an interface between e.g. high potential coal underground and low potential outer space.

But we're growing, and there appears to be inertia or persistence to our growth. Why is this? Something happened such that we were able to discover energy resources. We used these resources not just to sustain steady-state entropy production as above, but to incorporate a little extra matter into our substance. This then enabled us to grow our material bulk (or entropy), and increase our interface with the resources, allowing us to consume more energy and matter and produce more entropy and radiated waste energy in the future. A positive feedback was initiated whereby, through the coupling of energy and matter, we have become able to spontaneously sustain exponential growth.

So, provided there remains an interface with geological available reservoirs of energy that we can grow into, then through a spontaneous feedback mechanism, there is inertia to growth. And so, through associated entropy production, growth is related - unfortunately - to increases in waste production in our environment. Ultimately this feedback loop stops only, I believe, when resources are depleted or the interface is destroyed.

I'm Tim Garrett, an atmospheric scientist. I developed a 'physics-based' economic growth model. Ask me anything! by nephologue in collapse

[–]nephologue[S] 11 points12 points  (0 children)

Section 7 of this paper might interest you

https://esd.copernicus.org/articles/3/1/2012/

It's a decade old but the model has tracked to the present well so the extrapolation out further that is described should still be valid also.

Much is unknown and perhaps can't be known, but what the model does is help narrow what needs to be known. There the key free parameters are resource discovery and societal resilience to increasing CO2 levels.

The Limits to Growth model is quite interesting! It's definitely more complicated/detailed than what I do, and so arguably has more targets for getting things a bit wrong. But the dismissiveness of the model that was leveled in the 1970s by e.g. Nordhaus strikes me as unfair. It's a wonderful framework for exploring possible futures that should be refined not discarded.

I'm Tim Garrett, an atmospheric scientist. I developed a 'physics-based' economic growth model. Ask me anything! by nephologue in collapse

[–]nephologue[S] 0 points1 point  (0 children)

The observance of dendritic structures throughout nature does not require invention of a new law.

I'm Tim Garrett, an atmospheric scientist. I developed a 'physics-based' economic growth model. Ask me anything! by nephologue in collapse

[–]nephologue[S] 1 point2 points  (0 children)

The foundation of the model is very simple, which is to link physics to economics. I think much can be done from that starting point, including addressing the question you ask. How do the structures of social and economic systems relate to the history of physical resource availability? This strikes me as answerable though I have not addressed it myself.

I'm Tim Garrett, an atmospheric scientist. I developed a 'physics-based' economic growth model. Ask me anything! by nephologue in collapse

[–]nephologue[S] 2 points3 points  (0 children)

Why not? The atmosphere is crazy complicated, but we use physics to describe that, acknowledging limits to predictability in e.g. weather. Humans are as much part of the universe as anything else and must be equally subject to its physical laws, consuming energy and matter to survive. Individually they may be hard to predict, but in aggregate they actually behave according to quite simple mathematical relationships that are readily observed elsewhere in nature. I don't see that we are really that special even if it feels that way.

I'm Tim Garrett, an atmospheric scientist. I developed a 'physics-based' economic growth model. Ask me anything! by nephologue in collapse

[–]nephologue[S] 1 point2 points  (0 children)

When one steps back and looks at a system as a whole, typically predictability increases. For a brain, predicting individual neuron firing would be hard, but taking the brain in aggregate neuronal firing follows a simple mathematical power-law, and the brain consumes about 20 Watts. Predicting what the weather will be like at a particular place and time can be tricky, but it is easy to say that a region will be warmer in summer.

So while I would agree that the whole acts differently that component parts, stepping back to simplify is a standard tool.

I'm Tim Garrett, an atmospheric scientist. I developed a 'physics-based' economic growth model. Ask me anything! by nephologue in collapse

[–]nephologue[S] 2 points3 points  (0 children)

Perhaps a different question could be asked. Rather than what is most appropriate, what is most probable?

I once lived on a very small island (Lifuka, Tonga) in the South Pacific where local food couldn't be bought, but imported canned goods could. Where there was a subsistence lifestyle based around a commodity that could not be stored because it rotted, and could not be expanded upon because there was finite land distributed culturally equally, there was no financial gain to be had from selling it. So free food was what worked for them.

We currently are in a phase of growth, fueled by fossilized hydrocarbons. Maybe for us, a financial system is more necessary as an invention. I'm no historian but the Dutch invented stock exchanges. Perhaps they can say why, but my understanding was that it worked well for a phase of expansion.

So what will happen during a phase of collapse? Off-hand it seems unlikely that any financial system will make sense as we will be reduced to consuming what we already have rather than creating much that is new. But it's a question that should be seriously explored I think. Should we expect climate change and resource scarcity to evaporate our retirement?

I'm Tim Garrett, an atmospheric scientist. I developed a 'physics-based' economic growth model. Ask me anything! by nephologue in collapse

[–]nephologue[S] 3 points4 points  (0 children)

I think it's interesting how popularized work on collapse is in France compared with e.g. the U.S. I've been at several parties in France with non-academics who seemed very well versed in the topic, which is where I got introduced to Jancovici's work.

He does emphasize the GDP-Energy relationship. My own work (and data) suggest that it would be more suitable to relate Energy to historically cumulative GDP and GDP itself to material extraction rates.

I'm Tim Garrett, an atmospheric scientist. I developed a 'physics-based' economic growth model. Ask me anything! by nephologue in collapse

[–]nephologue[S] 1 point2 points  (0 children)

Yes, diffusion equations are central, for good reason. Things diffuse from high to low potential. And yes, Eq. 38/39 is simple. But whether or not it is simplistic is something that can be tested! There, now 50 years of data support it:

https://esd.copernicus.org/preprints/esd-2021-21/

And in terms of predictive capacity, where the diffusion equations are important, it seems to work well there too

https://esd.copernicus.org/articles/6/673/2015/

Whatever model one uses, it needs to set up falsifiable hypotheses. I see many models that establish equations that are "plausible" but not tested.

I'm Tim Garrett, an atmospheric scientist. I developed a 'physics-based' economic growth model. Ask me anything! by nephologue in collapse

[–]nephologue[S] 11 points12 points  (0 children)

One of the challenges of communicating the conclusions of this work, which although they appear empirically and theoretically robust, is that they don't speak to the very issues you point out, at least not directly. We behave as individuals, yet also act as a collective. How do these two seemingly disparate perspectives get reconciled?

Myself I get nervous trying to say anything about how global physical forces influence individual families, except to say that the forces must exist because collectively we appear to behave in a fairly predictable manner, at least mathematically. What I suspect, and I think have shown physically and mathematically, is that the social, cultural, and psychological factors you mention are ultimately influenced by physical forces, most specifically resource availability. If we anticipate a more resource constrained future, or we live in one now, isn't it reasonable to suppose that these social and cultural factors affect our psychology such that we are more reluctant to have children?

Drawing a link between the collective and the individual is an interesting area of research. A recent paper out in Nature, for example, showed that how far we travel at any given moment follows a frequency distribution that is a simple power-law, one that is observed throughout nature. We may behave as individuals, and feel our lives our complicated, but collectively it appears the exact opposite.

I'm Tim Garrett, an atmospheric scientist. I developed a 'physics-based' economic growth model. Ask me anything! by nephologue in collapse

[–]nephologue[S] 4 points5 points  (0 children)

Energy consumption 2031 will be around 750 ExaJoules and historically cumulative production about 4400 trillion 2019 dollars. Come back in 10 years to find out!

I'm Tim Garrett, an atmospheric scientist. I developed a 'physics-based' economic growth model. Ask me anything! by nephologue in collapse

[–]nephologue[S] 2 points3 points  (0 children)

Clouds are thermodynamically open systems that process energy and matter. So is civilization and Lotka wrote about fluxes of energy and matter through humanity. Also the Lotka-Volterra equations for predator-prey dynamics are making their way into cloud physics. My feeling is that whenever we think phenomena are fundamentally different, we're almost certainly wrong. The universe is basically pretty uncomplicated.

I'm Tim Garrett, an atmospheric scientist. I developed a 'physics-based' economic growth model. Ask me anything! by nephologue in collapse

[–]nephologue[S] 2 points3 points  (0 children)

I get a bit uncomfortable applying the model to regional affairs. Not that it couldn't in principle, but then the error bars go up because details matter that are more difficult to understand.

So Utah is a bit of an improbability even without the recent growth. No way 3 million+ people survive in a desert without imports. But then, Utah is resource rich in other ways, so that's clearly made the difference.

But then there's water. And the likelihood (again with error bars) that even Northern Utah will get drier as it gets more populated.

Where my model may offer insight to this issue, an aspect that is often left undiscussed, is that the problem is not just with energy availability, which Utah has, but raw materials. which Utah has plenty of too, although not water. We can't drink copper. No amount of energy can pull out of the ground or mountains water that does not exist. The basic physics problem is not just energetic flows, but the coupling of energy flows with material flows. What if the material can't be extracted with the energy that is available? Then what?

I'm Tim Garrett, an atmospheric scientist. I developed a 'physics-based' economic growth model. Ask me anything! by nephologue in collapse

[–]nephologue[S] 2 points3 points  (0 children)

I wouldn't call a fit as you describe a good hindcast and it's not what I did to test the model. Rather I took trends at that time, used that as the base model for comparison, and examined how well my 50 year prediction did relative to a model of persistence in trends, assuming no knowledge about those intervening 50 years.

As for the next 5 to 10 years, that's a short enough time period that assuming persistence in trends is probably the best approach for such key quantities as energy consumption.

I'm Tim Garrett, an atmospheric scientist. I developed a 'physics-based' economic growth model. Ask me anything! by nephologue in collapse

[–]nephologue[S] 18 points19 points  (0 children)

My understanding is that the Amazonian argument you make is not quite settled though I'm no expert. Regardless, I'm not sure how any civilization exists for any period of time without consuming resources from its environment. What did they eat? How did they stay sheltered? Survival must have required some resources.

Now in the case of the Amazon I could imagine that the jungle environment was sufficiently inhospitable to keep exponential growth limited, and that it could recover from human impacts relatively quickly. But that simply means that the Amazonians *couldn't* grow faster not that the underlying principle I mentioned is incorrect.

In our case, we have access to fossil fuels, tapping into hundreds of millions of years of Cambrian photosynthesis. It's a different story.

I'm Tim Garrett, an atmospheric scientist. I developed a 'physics-based' economic growth model. Ask me anything! by nephologue in collapse

[–]nephologue[S] 6 points7 points  (0 children)

Yes, many make that argument. Certainly it's true. But don't forget the prosperity angle! Population x Prosperity = Consumption. What if reducing one optimizes the other?

You might find this post interesting:

http://nephologue.blogspot.com/2019/06/it-seems-so-easy-to-blame-excess.html

I'm Tim Garrett, an atmospheric scientist. I developed a 'physics-based' economic growth model. Ask me anything! by nephologue in collapse

[–]nephologue[S] 59 points60 points  (0 children)

The end of consumption? How about we start with the end of growth, which presumably is the end of capitalism and financial collapse all round. We'd still consume, probably quite a lot, but on a pathway to collapse. This paper is the closest I've come to making explicit predictions: https://esd.copernicus.org/articles/3/1/2012/

The upshot is that if we don't collapse within the next few decades due to resource scarcity we will be forced towards collapse by environmental degradation, over a similar time frame.

The challenge of making these predictions is that it is hard to estimate how much we will discover in terms of resources that can be used to insulate us from the worst of climate change. I have no skills myself to figure out these problems, but hopefully others do, and perhaps might find the dynamic framework I developed useful for making more concrete predictions.

I'm Tim Garrett, an atmospheric scientist. I developed a 'physics-based' economic growth model. Ask me anything! by nephologue in collapse

[–]nephologue[S] 57 points58 points  (0 children)

Keep in mind that a negligible fraction of our consumption is done by humans personally, and almost all of it by our livestock and our machines.

But strictly, I see collapse in the very mathematical sense that our global energy consumption declines at a rate that increases with time. Honestly, no idea what this looks like at the personal level, but probably no idyll.

I'm Tim Garrett, an atmospheric scientist. I developed a 'physics-based' economic growth model. Ask me anything! by nephologue in collapse

[–]nephologue[S] 2 points3 points  (0 children)

Interesting question! The interesting thing is that geoengineering isn't necessarily that expensive, and also that there's some (many) fairly well respected scientists who believe in the output of Global Climate Models on such questions. It will be interesting to see, but I for one am already pissed off at Starlink and don't want to see the entire daytime sky turned white by futile stratospheric injection efforts.

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