Do you ever wonder if we’d run out of trees? Seems like a ridiculous notion given that they seem to be growing nearly everywhere. Yet today satellites give us extraordinary views of Earth’s land cover. They clearly show that the trees, or more accurately the forests, are changing and the change may startle you.

First, let’s look at broad numbers. Currently, the Earth’s land cover could be set into thirds; a third is barren or glacier covered, a third is use by people for agriculture and a third is forest. A third is a huge amount, about 43 million square kilometres. While the forest area is huge, it’s a change. It’s only about half the forested area of pre-human days. And we’re continuing to decrease forested area by 0.2 million square kilometres each year. Hence, broadly speaking, in about 200 years the forests will be gone; that is, we’d run out of trees!

Probably all conservationists, and most people, want to keep forests. Not only do they harbour wildlife, they also rejuvenate Earth’s atmosphere. We can keep forests in two obvious ways. One way is to stop forest degradation. This is the aim of REDD+. The other is to grow forests, i.e. to plant trees. This is the aim of the Trillion Tree Initiative. Let’s look at the latter.

The Trillion Tree Initiative is for people to plant a trillion trees. Simple enough. But where do we plant them? Assume on average that a hectare can support 600 trees. Thus, a trillion trees would need about 17.5 million square kilometres of land, another huge amount! On the plus side, these trees would sequester carbon thus reducing atmospheric carbon dioxide. And they’d store about 7.3×1021 Joules of potential energy. On the negative side, the Earth has no available land area; all habitable land is already allocated. And we’re changing 0.2 million more square kilometres each year from forest cover to agriculture cover. Thus, planting a trillion trees won’t likely occur given our reliance on today’s agriculture and food industry methods.

What this exercise shows us is the mathematical simple yet realistic challenging way to save trees. Trees, much as with animals, need land to grow. As we change natural land cover to suite our needs, we reduce the number of trees. And yes, trees can go extinct. So, while we can run out of trees, are we willing to act to prevent this and to regrow forests?

Before / After:

Solar Power Generation

Solar power generation is on a growth spurt. In 2018, it produced over 584 TWh of energy. Its capacity is nearly doubling every two years. Some see solar power as being the solution for global energy needs.

However solar power comes with costs. For one, there’s the need to fabricate panels, construct the collector facilities and then maintain operations. For another, all life forms below the solar panels will die-off as the Sun is their only source of energy and the panels capture all the sunlight. Thus, solar power usage needs to be rationalized with costs of other energy supplies.

Can we scale our energy challenge? Certainly; let’s see. In 2018, we consumed over 160,000 TWh of primary energy and it is increasing by about 1.5% annually. If solar power supplies all this then we’d need cover about 14 million square kilometres of land with solar arrays and then maintain operations.

This operational area is huge, greater than all of Europe. Further, implementing this solution would drastically, negatively affect the Earth’s biodiversity. Thus solar power generation has its place in the global energy supply mix but we need other, less costly, means to satisfy our energy challenge.

Our Baseload

The COVID-19 pandemic reminds us again that we are human. Normally we live, create life and eventually after many years we hope to die of relatively painless old age. This pandemic sees many people across the world dying long before old age expectations. The final effects on human birth and death rate may be as noticeable as with the Spanish Influenza of 1918.

With many countries mandating only essential activities because of COVID-19 then we’d also expect energy consumption to drop. And it has. But for the first quarter of 2020 it only dropped by about 3.8%. The second quarter sees a reduction of 10% from the previous year. Now, given the continual proclamation to restore economies, we’re seeing activities return to usual and energy consumption responding in accord.

This small drop in energy consumption due to COVID-19 indicates that even while we are cloistered at home we still demand a huge amount of energy. Also, it indicates that if we continue to rely upon the economy to nurture our lives and give us a grand old age then we need continual access to huge amounts of energy. What happens when we consume all the non-renewable energy sources?

Plan the Future

Can a civilization have an existential crisis? To answer, lets scale the civilization. Given our ever shrinking global village, well say that theres only one civilization on planet Earth. This civilization measures itself via Sustainable Development Goals. This civilization nurtures itself through aid packages and trade deals. This civilization even contemplates its future via Shared Socioeconomic Pathways (SSP) in Earth System models. This indeed seems a civilization and one that is robust. But why does it exist?

The SSPs might be the best avenue when considering existence. These pathways attempt to model the civilization out to the year 2100. Through various assumptions on resource availability, technology development and population, experts move qualitative narratives to quantitative values. Energy is of course central to this and the expectation is that demand in 2100 will increase from the current 350 EJ energy to a range of 400 to 1200 EJ based upon scenarios. Anyway you look at this, the energy demanded by existence goes up, sometimes significantly!

So the civilization exists and will be using more and more energy. For what purpose? Is it to maximize everyone’s standard of living? Is it to maximize procreation? Or perhaps it has no real purpose and planning for the future is simply leisure (le loisir). How do you think energy be best applied to achieve your imagined future? What value do you see in civilization?


Land Use

The Earth is a rocky sphere that orbits the Sun. Via plate tectonics it recycles its surface. Currently the land portion of Earth’s surface has an area of about 148.9 million square kilometres. This is expansive. For example, the whole surface area of the Moon is only about 6% of this; just the area of Europe. So we have lots of land to use as we see fit.

Let’s consider our use of the Earth’s land surface. We know the use from satellite data that measures the area of certain types of biomass. In 2017, the FAO estimates that agriculture covered 4.83 billion hectares, that forests covered 4 billion hectares and that other land such as deserts and barrens covered 4.165 billion hectares. While these numbers are just shy of the estimated total land area, they provide a very clear division of land use.

Let’s stop and think about these values. From them we see that humans have mastered the planet’s surface. Our agricultural area exceeds the forest area. Add infrastructure area (i.e. cities) to the agricultural area and the human affect becomes noticeable greater. We have taken over! And to think that only a few thousand years ago people had neither agriculture nor cities. What does this imply about land use for the future?

Land Use – All within 1km