There are limits to what Nature can provide
Every organism must live within the limits imposed by physical and ecological laws and principles or suffer the consequences. For example, you can choose to jump from the top of a 100 story building, ignoring the law of gravitation; however, within about 10 seconds you would suffer the consequences. Unfortunately, most of our activities that ignore these basic laws don’t have such immediate consequences.
The following are a few examples of the natural laws and principles that affect us every day and play a role in our efforts at becoming a sustainable society, whether we know it or not:
Laws of Thermodynamics
The First Law of Thermodynamics states: Matter-energy cannot be created or destroyed. In practical terms this means that if matter-energy is here but it can’t be created and it can’t be destroyed, then what we have is all there is. That is, there is a finite amount we have here on Earth with one exception: sunlight from an average star some 150 million kilometers away that continually bathes the earth in solar energy. But matter on the Earth is surely finite. And since we use that matter as input to our economy in the form of resources or natural capital, for example, can you imagine what effect this law has on our perennial demand for economic growth?
The Second Law of Thermodynamics states: Matter-energy spontaneously tends to move only from a concentrated form to a dispersed form1. The measure of this dispersal is called entropy, which always increases. In practical terms, the more dispersed the matter-energy is or the higher its entropy, the less useful it is to us. So we not only have a finite amount of matter to work with but it is constantly moving from low entropy (usefulness) to high entropy (uselessness). This law explains why a perpetual motion machine is impossible and why a glass of ice water in a warm room always warms up melting the ice until its temperature reaches that of its surroundings; it never spontaneously cools down to form more ice, unless an outside energy source is used.
Ecological Carrying Capacity
Carrying Capacity is the maximum population size that can be supported indefinitely on the landscape by the available (i.e., local) resources without impairing the functions and productivity of the ecosystems on the landscape.
There are those who believe that the concept, carrying capacity, no longer applies to humanity because of our ingenuity and technological advances. But ecological studies have shown that no organism is exempt. Consider our large cities. It is easy to see why carrying capacity is not considered in the day to day activities of the city. However, these activities are only possible if tonnes of foodstuffs are delivered to the city from production areas far away using trucks and other forms of transport that are dependent on cheap fossil fuels.
To think that our ingenuity coupled with increasing efficiencies will allow us to ignore carrying capacity forever, is anathema to sustainable living on a planet with finite resources one of which will ultimately prove to be limiting (see below). In fact, there is good evidence that we have already exceeded the carrying capacity of the planet2.
Liebig’s Law of the Minimum
Leibig noted that for every population, there will be a limiting resource which determines that population’s carrying capacity.
The concept of a limiting resource or limiting factor is important to the understanding of sustainability. A limiting resource is a resource, such as food or water, that controls a process, such as the size of a population. If that resource, or it’s lack thereof, is affecting the population in a negative manner, and you don’t address the limiting factor, then anything else you do to help that population will be for naught and the population will ultimately be eliminated.
Law of Competitive Exclusion3
When two species compete for a limited resource, one species always eventually wins and the losing species becomes excluded from the ecosystem (locally extinct).
This law has significant implications to the planet’s biodiversity because the breadth of the human niche is so wide—that is, we’re now using up resources virtually everywhere on the planet—that much of the biodiversity of the planet is being lost through competitive exclusion.
There is a general mistaken impression that when a species’ habitat is lost to development or other factors in one particular place that the species can just go somewhere else. But that would be similar to you going home one night and finding your house burned down. Would you think, well, too bad, but there’s a house across the street; I’ll just go over there? Faulty logic, of course, for the house across the street—like other similar species habitats—is already occupied.