Closed Ecosystems

As Star Trek put it, ‘Space: The Final Frontier’. It’s not all make believe. We have travelled in space. However, building a sustained human presence in space is a whole other level. Effectively, we’d need to create and protect a sustaining ecosystem; a system akin to the one that’s keeping us alive on Earth. An obvious challenge to achieving this is knowing what’s essential to keep us alive while we explore the nether regions.

Looking at our current tentative forays into space, it would be easy to assume that all we need is a secure container full of breathable air. But if we want to live up there for more than a few hours, then we need to bring along food and water. And eventually, we’d need to dispose of our waste. Thus, to sustain ourselves over a long time, we’d also need to process our waste into something useful. With such a sustaining, closed ecosystem, we could travel to other solar systems or build bases upon Mars.

Vitally important to our planned, closed ecosystem is the energy that enables all these processes to perform. On Earth, the Sun provides nearly all this. And this also makes the Earth ecosystem an open system. Now, imagine travelling to other solar systems. Then, we expect no appreciable energy from our Sun. Instead, we’d need to gather and store all the energy before we departed. As we can’t gather anything in the void of space, our space-faring ecosystem has to be closed; except perhaps some radiant heat energy losses.

There is no manifest destiny drawing us into space-based habitation. We could remain on planet Earth. Our species could endure for many tens of millions of years, as did the dinosaurs. But we would always be limited by what’s available on Earth. After climbing every mountain and descending into every trench, writing every story and singing every song, then we’d live simply to relive the past. There would be nothing new to our destiny.

In space, there is no known limit. However, our current capability is nowhere near a sustaining, closed ecosystem. Further, we seem to be radically, negatively affecting the existing ecosystem on Earth. Why do we prefer to build roads, to play video games and to engaging in warfare on this functioning ecosystem? What do these preferences say about the development of a sustaining, closed ecosystem for humans in space? And what do they say about our future on Earth?

Earth, Start-point or End-point

Do you enjoy watching science fiction cinema? There, people dramatically meet other life-forms or overcome daunting obstacles. From it, we have the sense that our species is special and capable of anything. Given the plethora of such films over the last few decades, perhaps we over-confidently believe that such events will be our future. It’s just a matter of time.

The science fiction genre really developed just prior to the turn of the previous century. Its progenitor, Jules Verne, wrote ‘From the Earth to the Moon’ in 1865. In that year, about 1.3 billion humans used an estimated 2.9×1019J (8,005 Twh) of energy in their annual strivings. Today, on Earth, over 8 billion people use an estimated 6.4×1020J (178,899 Twh) annually, mostly from fossil fuels. But, instead of reading about space travel, we routinely watch films having people comfortably zip at faster than light speed to remote stellar galaxies.

In reality, space travel is anything but routine. A lucky few have visited Earth’s Moon. Will our future include space travel? Unlikely. As demonstrated with the USA’s Apollo space program, tax dollars only get expended on undertakings that benefit all or most. Further, individuals can’t afford to encamp our species on another world. So, Artemis and ILRS will go the way of the Europa settlement. That is, nowhere. Instead, people will continue watching science fiction and imagining. What does this say for our future?

Swallow flight

Energy to Survive

We’ve already noted that we live on a finite world. When people use its resources, regardless of whether renewable, the resources are not available for anything else. Our current use of energy enables both our numbers and our technology to flourish. A growth economy assumes this approach is without end. It assumes we live on an infinite world.

As you can well imagine, eventually the energy supply will not meet the energy demand, as our world is finite. How do we address this? In a market economy, if a product or technology is unsustainable, then it disappears. Will we hold the same principle to life? When the energy supply to support life proves inadequate, then people disappear. Perhaps we let people choose for themselves. They may choose between either technology such as a cellphone or food such as bread. Those who choose badly will disappear and, eventually, energy demand will equal supply.

Should we extend this same logic to all life? Wildlife needs both energy / food and space to flourish. Sometimes numbers explode as for mammals after the Cretaceous-tertiary extinction event. And we see numbers crash as with reindeer on St Matthew Island. Logically, if people consume most of Earth’s energy resources then wildlife numbers will crash. With the continual rise in our energy consumption, are we unknowingly planning a future Earth that will sustain life only for some humans together with their chosen support creatures?


We describe planet Earth as being in the ‘Goldilocks Zone’ for life. What does this mean? It means that Earth’s orbit about the sun is at just the correct distance for life to exist. In particular, Earth’s surface maintains water in a liquid state. If the Earth were colder, the water would be solid, i.e. a snowball Earth. If the Earth were warmer, the water would quickly vaporize, making Earth unsuitable for life. Today, neither of these conditions exists, so life on Earth flourishes.

However, the Earth’s surface is a system that balances heat. Heat comes from the Sun and from the Earth’s core. Heat gets emitted as radiation. If these balance, then the Earth’s temperature remains constant. Obviously, if it doesn’t balance, then the Earth’s surface gets either hotter or cooler. We are now seeing an imbalance as temperatures are increasing.

The Earth’s oceans have heated by 337 zettajoules (3.37×1023 J) since 1955. The Arctic ice and mountain glaciers are melting. Indications are that human actions have caused this change; this imbalance. In corollary, we are changing the temperature of our bowl of porridge. Goldilocks will no longer be content with it. Nor will life flourish with it. Is this our future?
Desert Sky

Future Population

Have you ever wondered how many people could fit on Earth? Likely there’s more now than at any other time in Earth’s history, almost 8 billion. Yet what of the future? The World Bank predicts a peak of about 11 billion sometime this century. Or, there’s talk of a human population crash with the total dropping greatly. Yet, the population might just keep climbing to some, eventual maximum. That is, we don’t yet know how many people could possibly fit.

Let’s say the population remains the same as today. If so, then we certainly know the problems and for the most part the solutions. Such as, we’re on track to addressing climate change. We understand the importance of biodiversity and the value in preserving it. And, we realize that finite fossil fuels need be replaced by renewable energy sources. That is, the Earth might sustain the current population.

However, what of a population that continues to climb? A consequence is increasing pressures on Earth systems as people demand more energy, more food, more resources. That is, instead of solving problems, we’re exacerbating them. Climate change is quicker and greater. People use more land for themselves thus allocating less for biodiversity. And, we need all sources of energy even those not sustainable. This lack of sustainability means that Earth systems fail and eventually fewer people could fit on Earth.

Is there value in setting a maximum to the number of people on Earth? How would you calculate this value? And more important, how would you enforce this value?
Great Bear Lake