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The Next 30 Years - Sustainability on Planet Earth

Section 1 - The Big Picture

Chapter 3 – The Next 30 Years

Julie Smith, April 5, 2022,

This blog provides an overview of chapters in my book on sustainability. I will post a blog summary as I complete each chapter, with a link from the chapter title at the top to the pdf of the complete chapter. The complete chapter provides more details that support the discussion in the summary, and includes the references that were used.

What you will find in Chapter 3:

What can we do in 30 years? The three legs of sustainability. Possible futures. What if we plant some trees? Two legs of sustainability. All three legs. Population-carbon nexus.

What can we do in 30 Years?

Make no mistake, the next 30 years will be very telling, in terms of whether or not we can turn the anthropogenic destruction of our planet around. If we can get it turned around, with less overall emissions, and start to see signs of improving balance, like decreasing atmospheric CO2 concentration, decreasing average temperatures, cessation of sea level rise, and recovering populations of wildlife on land and in the oceans, we’ll know in the next 30 years. If we can’t get this turned around, we’ll know that in the next 30 years too, as the consequences will be clear if we continue to push our planet past the tipping point.

That wouldn’t be a happy thing. We would continue to see increasing loss of more and more species and life forms, and increasing food scarcity and drought for those of us who are still here, with increasing storms and wildfires, and increasing losses of loved ones to disease, starvation, wars and murder as we continue to lose personal rights, freedoms, flexibility and resources.

Since we can’t exactly know what’s going to happen, I will turn to modelling, in order to get an idea of what our cumulative impacts could be if we take action, or if we don’t.

The three legs of sustainability

We already know that atmospheric CO2 concentration is related to temperature, and that human CO2 emissions increase the CO2 concentration. We also learned that the more people we have on the planet, the more total CO2 emissions we have. We also saw how much forest cover we have currently, and we know how much CO2 trees can absorb, which tells us how much we can increase the CO2 sink with trees, to offset our emissions. Ideally, the ultimate goal here would be to get the planet’s natural CO2 sinks approximately even with how much CO2 we emit.

If we want to keep our model simple, while giving us a good idea of what we can expect in the future, these three variables, total CO2 emissions, total human population and total forest cover, seem like a good place to start. They should tell us most of what we want to know, given that together they comprise about 80% of the underlying causes of global warming. Also, these are three things that we can actually control by modifying our behavior. Unlike other stuff, like earthquakes and volcanoes. So, why bother with those? They only make up about 20% of the problem anyway.

Possible futures

The main assumptions I had to make were around trees and forests, since the references I found were all over the map, with CO2 uptake for trees ranging from 16 to 55 LBS per tree per year, and tree densities from 229 to 1000 trees per acre. I finally settled on throwing out the extreme numbers and taking averages of the others. Table 1 is an overview of the assumptions used in this model.

As a starting point for our model, we have current human population on the planet, 7.71 billion, and total carbon emissions of 40.53 billion tonnes/year, as of the end of 2019.

Our goal with modelling is to see what happens if we plant a bunch of trees, or if we reduce our CO2 or our population. Or if we don’t do anything. The first graph, Figure 1, which we’ll call “Business as Usual”, models the next 30 years of CO2 emissions if we continue our current practices.

Figure 1 shows that business as usual would result in continued increase in CO2 emissions, up to 58.7 billion tonnes/year, about eight times as much as the emissions in 1910. If our goal is to get back in CO2 balance with our planet, the “Business as Usual” scenario definitely won’t get it done. Our population will also be well over 10 billion by then. We’ll have further depleted the forest cover that we need for a carbon sink.

The good news, if you want to call it that, is that we don’t really have enough fossil fuels to do all that. In 30 years, if we don’t move away from fossil fuels, we’ll run out. Given that reality, we would do well to make sure we figure out alternative sources now and get them into normal use across the globe.

Using the same assumptions from Table 1, Table 3 shows an overview of modelling some different cases, or scenarios that could happen, at least in theory, depending on what measures we take.

If we can begin to reduce our global population by 0.5% per year, or by 1% per year, reducing global population has a really strong impact on our CO2 emissions. A gradual reduction in population, just changing our 1% annual increase in population to a decrease of 1% per year, would get us about halfway to where we need to be.

What if we plant some trees?

In Table 4, Cases 7 – 9 show the impact of planting increasing numbers of trees, while stopping population growth.

Now, let’s see what happens if we try simply reducing our carbon footprint per capita. This will include all that awesome renewable energy technology, other cool stuff that saves energy, EV’s, and our own personal choices. It turns out we can save more energy faster with our own personal choices than the best of the latest and greatest technology. And money, too. Just by paying attention to what’s going on and not wasting. It’s not hard.

A reduction of 5% would get our temperature almost down to where it was in the pre-industrial period. At this point, notice that the global average carbon footprint would be reduced to just over 1 tonne per capita per year, which is equivalent to the poorest of nations.

Two legs of sustainability

This brings us to the next question in our modelling. What happens if we address just two of the three legs of sustainability? What if we get all those trees planted and each of us steps up and reduces our individual carbon footprint? We also leave the population the same.

Table 6 shows that as long as we plant all the trees we can, then we can make some real headway with individual carbon footprint reduction. To get down to pre-industrial temperatures, we would need to reduce our carbon footprint by 2% per year, shown in Case 17. This would result in net carbon emissions of just under 10 billion tonnes per year, and each of us would be using about half of what we use now. So, not a bad outcome, although it’s extremely important that we avoid growing our population for this to work. And we absolutely must reforest all available land.

All three legs

It looks like we’ll need all three legs to get back to the pre-industrial balance we had with our planet, so, our final set of cases will include all three legs of sustainability. In Cases 18 – 20 in Table 7, we can see the impact of increasing annual reductions per capita if we reduce our population by 1% per year, and plant 50 billion trees per year. The global population would be just under 6 billion, about where we were in 1998, and we’d have a lot more flexibility in carbon footprint per capita. This is a very comfortable and realistic scenario, and our future descendants would likely be fine. They probably wouldn’t even notice a serious difference in lifestyle. Personally, I would feel pretty good leaving this future to our children.

Population-carbon nexus

One caveat to consider is that the more people we have on the planet, the less personal flexibility each of us can enjoy as individuals. And, the less individual flexibility, the lower the individual freedoms and the higher the frustration. Knowing that, in reality, it will be a long time before forested land actually increases, we really only have two legs of sustainability that we can really count on in the near-term. Those are a combination of reducing population and reducing carbon footprint per capita. On forests, in reality we will have to plant a lot more than 50 billion trees per year just to keep up with the current losses from wildfires. So, we need to get started on the CO2 reduction per capita and combine it with kind, gentle, gradual population reduction now, in order to avoid a complete implosion, just in the next couple decades.

The optimist in me thinks this is achievable, as long as we’re serious about switching to renewables in particular, and continuing to develop technologies that are efficient. Also, we waste a lot of resources currently, and just eliminating that waste will get us a long way down a better path. It’s a lot of work and a lot of change, to get down to a third or less of where we are now in terms of overall net emissions. If we don’t include measures to bring our population into balance, we will either fail to get in carbon balance with our planet, or each of us will face a severely reduced lifestyle, with increasing restrictions on our personal choices and freedoms, at the very least.

So, at this point, I still think we as a human species still have choices. We can choose to act now for a better future, involving peace and plenty for all, or we can choose continued arrogant complacency, and secure a future of war, insecurity and misery for all. Now that we have established a case for change, the remainder of this book will be dedicated to what we need to do. If you want to make a difference, read on. Thank you for joining me!

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