Shrinking the economy won't save the planet

Wikipedia says there are more than a hundred billion wild mammals. [1] They obviously do not all consume as much food as humans do and there are certainly a lot of small mammals like mice, but from the order of magnitude it seems at least not completely obvious that ten billion people would be too much to support without fertilizers other than dung and similar things.

From a different angle, Wikipedia says there are about 1.4 billion hectares of arable land and the best number I could quickly find is that one needs one to two hectares per person without modern fertilizers, that would imply a limit of only about a billion people.

[1] https://en.wikipedia.org/wiki/Lists_of_mammals_by_population

[2] https://en.wikipedia.org/wiki/Arable_land

I prefer total energy use as a measure of human progress. At the end of the day, money is a proxy for energy consumption. By people in their labor, by machines, by the processing of information. Fortunately, it is steadily increasing.

> Can we keep growing by a few percentage points a year for the next few centuries? Yeah, probably

2 percent a year for 200 years (the minimum rate and years that could count as a few) is a multiplier or around 52.

For population that would give about 400 billion.

> Can we do that until the heat death of the universe and beyond? Probably not.

For population and energy we hit severe physical limits long before that.

At 1% annual growth in population in 12000 years we run out room. What I mean by "run out of room" is that assuming no FTL travel then since every human right now is on Earth or in low Earth orbit no human 12000 years from now can be more than 12000 light years from Earth. The volume of a sphere 12000 light years in radius, divided by the population after 12000 years of 1% growth, is less than the volume of a human.

How about energy? 9300 years of 1% annual energy growth starting now reaches a level where our annual consumption equals the energy of the entire Milky Way galaxy. By "energy of the entire Milky Way" mean everything...electromagnetic radiation, gravitational potential energy, the E=mc^2 energy of everything that has mass.

If we can somehow actually do that, 2700 more years of 1% annual energy growth and we are annually consuming the entire energy of the observable universe.

Its similar when you look at the mass to make human bodies. Here's what 1% annual population growth looks like in terms of mass needed: 3400 years to where the mass of human bodies equals the total mass of Earth and Moon. 600 more years and we also need Jupiter's mass. 700 more and we need the mass of the whole solar system.

Then it is another 2000 before we need the mass of the entire Milky way. 100 more years and we need the Andromeda galaxy's mass too. That's 6800 years from now. Then it is 5500 years until all mass in the observable universe is needed for human bodies.

Unless we get FTL travel it seems pretty clear than sometime in the next 12000 years either growth must slow or we have to change humans to require a lot less space, mass, and energy.

(I haven't read the article yet so apologies in advance if this is just noise, but uh...)

A lot of people seem confused about "degrowth". (In quotes because it's a terrible neologism.)

Look, people, degrowth is going to happen.

It's not optional.

We overshot basic physical realities and a "correction" is coming.

The question is not whether we drastically change our economic and industrial systems, because that's going to happen no matter what, the question is how to soften the disasters so that billions of people don't die in the next century or so.

Just to hammer this home: things will change, because Nature will change them for us. We can try to mitigate the worst of it, but we will have to scramble.

The good news is that we know what to do and how to do it. We could fix things overnight (well, within a year or three) if we really put our minds to it, because we already have all the solutions (most of them were worked out in the 1970's!)

The debate about degrowth is not whether or not to do it, the debate is whether to cushion the blow or just run off the cliff.

> Total energy dissipation is at best a crude proxy for progress, because efficiency.

The relationship is still positive, because of Jevons Paradox. No matter how you see it, even if there are bad diminishing returns to using additional energy, we can find additional useful things to do with it (new ways of recycling, terraforming, high-energy synthesis, etc.)

> In order to measure "progress" you have to determine what is good, which is an open-ended question that increases in difficulty as one's intelligence grows

Reducing suffering is probably the only universal good that I can think of, but we haven't even managed to come close to making it our priority. So until we focus on that, it's a good goal.

The best way to reduce suffering is through good healthcare and keeping a working social contract/order.