As we race toward the end of our fossil-fuel age, possibly the total end of our energy age, one of the heartbreaking truths that our species must endure is that our dream of reaching out to those stars is likely never to be realized. We evolved as an earthbound species and will likely be forever constrained to that reality. We desperately want to believe that somewhere out there circling some of those billions of points of light there are other planets, like our own, teeming with myriad life forms. The reality is that, despite an incessant search, the only planet in all of this vast universe that we know contains life or even has the ability to sustain life like ourselves is this one, our own beloved planet earth.

I understand those fervent hopes and dreams of finding other life in the universe. I share them. I passionately and desperately wish that SETI would receive that elusive signal from other intelligent life out there. Perhaps for the first time that would convince us all of what we have in common, that we are one us in a universe of them. But there are so many more reasons that we never will receive that signal than reasons that we might. Whether we ever receive such a signal does not likely alter the reality that we will continue to be dependent upon this planet for our existence. Should we ever succeed in venturing into deep space the number of us doing so would be very few and we would still have to further borrow from the resources of this planet for the life-support system that would sustain us on that voyage. But this shall always be our home. Our galactic passports will always identify us as citizens of earth. On the first page inside there will probably always be a stamp declaring "no exit visas allowed." Here is home. Here we stay. We need to make the best of it. We need to be mindful of the constraints that reality imposes on us.

Our solar system, for example, is a closed system. It is what it is. It receives no inputs from elsewhere in the galaxy or the universe. Our earth is a semi-closed system, receiving input from only one source, the energy reaching us from our sun as it, like all stars, slowly consumes itself. All of the resources that this planet contained before life arose are finite resources, limited to what was here in the beginning. Most of the resources since created by the living processes of this earth are renewable, not infinite but perpetually recreated by living organisms. Most of those renewable resources, the living organisms, are themselves created from the finite resources, the minerals and other chemical elements with which this planet was originally endowed. Life on this planet constantly reuses and recycles those elements through one living organism after another.

Some of those organisms still receive their sustenance directly from the native resources of the planet, converting raw minerals and other elements into a form that they themselves and other organisms can utilize. These are descendants of some of the microorganisms that first built life on earth, that originally used the raw resources of the planet to develop an environment capable of supporting millions of varied species in every part of the planet. They, in turn, make those resources available to the roots of plants and plants make them available to the animal species of the planet who eventually return them to the soil when they die where the microorganisms start the process all over again. Nature wastes nothing.

Life is still critically dependent on these organisms today for extending and maintaining the life support capability of the planet. Every ounce of raw planetary resources converted by them to a bio-available form extends and maintains the amount of life this planet can support. The resources those organisms convert into a life-supporting form, however, are finite and in these first few billion years of life on this planet the most readily available and easily obtained resources have continuously been drawn upon by this planet's life forms.

All finite, non-renewable resources consumed, whether by man, the other life on the planet, the environment, or any other agent, will eventually be used up. All finite resources used intentionally will generally be used in increasing amounts as the amount of draw-down of that resource gradually increases to maximize the use of the resource available. The amount of consumption of any finite resource will generally be at it's maximum at the point where about half of that resource has been consumed. This is the peak, just like Hubbert's Peak which describes the point of maximum consumption of the world's crude oil supply. Oil, interestingly, though created from living organisms, is nonetheless, for all practical purposes, a finite resource. It is renewable, in that the same processes that created the oil we now use can recreate it. But the timescales involved in converting living matter into oil are so long, on the scale of millions of years, that in human terms we must consider oil finite. The abiotic oil theory, which we will here ignore, argues otherwise. It claims that oil is generated from inorganic material deep in the earth's mantle and gradually migrates up through miles of rock to the reservoirs where oil is found.

There is another critical factor that is rarely considered or discussed concerning the consumption of finite resources. It is, in fact, part of the central reason for this paper.

The agent using that finite resource builds a dependence on it consistent with the amount of that resource being consumed. That dependence generally is at its maximum when consumption is at its maximum, when that resource has reached peak and is half used up. That slow build in dependence has followed the gradual build-up in consumption. As that resource passes peak and its availability goes into decline so too will the agent responsible for its consumption. That, of course, is not limited to finite resources. Such a dependence can also be built around a renewable resource that goes into decline because the agents consuming it are doing so at a rate faster than the resource can be renewed. The number of Koala an area can support is dependent on the rate at which the Eucalyptus trees on which they feed reproduce. Pandas are dependent on the reproductive rate of bamboo. Cheetah's rely on the reproductive rate of Thompson's Gazelles. In that sense oil is similar. Oil can be reproduced but the rate at which it can be regenerated is far exceeded by the rate at which we consume it.

There is one species consuming and destroying this earth's finite and renewable resources at a rate far exceeding that of all other life forms on the planet combined. That species is, of course, homo sapiens, man. Our activities, unlike those of any other species, are systematically destroying the life-support capability of the entire planet. Carried on long enough with enough vigor we will destroy the ability of this now-living planet to support any life at all, ourselves included.

This is only partially and indirectly due to our consumption of fossil fuels and finite mineral resources. This planet's life-support system consists of various components and sub-systems like the water cycle and the carbon cycle. The one component, however, most critical to land-based life, the engine of their life-support system, is the soil. More particularly it is the top soil, that thin layer of dark, organically rich, nutrient heavy soil in which plants spread out their roots and upon which animals walk and urinate and defecate and give birth and die. It is in this thin, vital layer of soil that land-bound microorganisms convert the raw resources of this planet and make it available to the myriad forms of life around and above them.

The human body, like that of most other animals, contains trace amounts of almost every mineral on earth; carbon, calcium, sulfur, phosphorus, potassium, gold, silver, zinc, copper, iron, aluminum, molybdenum, chromium, platinum, boron, silicon and more. These are derived from the soil through the plants and flesh we eat. But it is those soil microorganisms that start the process by converting those native minerals and make them available to the roots of plants in a form that other living organisms can utilize.

Some would ask why all those minerals are in our bodies, why our bodies need them and what they are used for. The amino acids that our body's proteins are made from, after all, contain only carbon, hydrogen, oxygen, nitrogen and sulfur. Our bones are constructed mostly of calcium, silicon, and boron. What are all of those other minerals used for?

All living organisms are vitally dependent on two particular types of proteins that control the metabolism, the conversion of food to cellular material, the functioning of the nervous system, cell regeneration and more. Hormones are the body's internal messaging system, if you will. They control your body's rate of cell reproduction that controls your growth, your nervous reactions, cell division, immune responses, the contraction of muscles and more. Enzymes are the catalysts involved in the conversion of material from one form to another, responsible for the physical construction and maintenance and division of cells, responsible for the conversion of glucose to energy, and much, much more. There are literally tens of thousands of different types of enzymes in your body. It is a bit of a stretch but fair to say that everything that happens in your body happens because of enzymes.

Enzymes particularly, and also true of many hormones, are proteins very precisely built to specifications contained in your DNA to do one very specific function. It may, for example, be responsible for combining together a carbon atom and an oxygen atom or splitting apart two joined sulfur atoms united by a disulfide bond. An enzyme generally does only one very specific function and no more. In order to carry out that function, however, most enzymes required a catalyst. A catalyst is a substance that acts as an agent in speeding up a chemical reaction (getting the carbon atom and oxygen atom to link or getting the two sulfur atoms to separate). These reactions would take place without the involvement of the enzyme and catalyst but they would do so at such a slow rate that life as we know it could not function. Movement would not be possible. Your body would be unable to build replacements for your damaged or worn out cells. Food that you ate could never be converted into useable material in your body or converted to energy to drive your muscles and nervous system. Enzymes quite literally are the key to life.

You are probably aware of the handful of your body's digestive enzymes that break down the food you eat. But the vast majority of the tens of thousands of enzymes in your body are contained within your cells, are generated there, do their function there, are broken down and recycled there, never exiting the cell in which they are created. The food you eat, in fact, may be acted upon by hundreds, even thousands of different enzymes-like workers on an assembly line-from the time it enters your mouth until it is used in various bodily processes or built into a cell.

The key to the enzyme's ability to do it's job, like the assembly line worker, is the tools it has to work with, the catalysts. A particular enzyme may use as a catalyst a particular vitamin, an atom of oxygen, or more likely an atom of a particular mineral like iron or gold or silver. All of those various minerals in your body are used somewhere. If they are not used in the structure of your bones and cells and nerves and muscles then they are used by hormones or by enzymes as catalysts in completing the chemical reaction that enzyme is responsible for. Without it's required catalyst-like the assembly line worker without his tools-the enzyme cannot do the job it must. Also like the assembly line worker, if one enzyme involved in a series of enzymatic reactions can't do its job the whole assembly line, the whole series of events, shuts down because all the enzymes after that can't get their materials. If the body, for example, does not have functioning amylase enzymes (responsible for the breakdown of starches in the digestive system) then all of the bodily functions dependent on the nutrients in starches will not be able to function because their materials are, in a sense, held up at the receiving dock.

The food we eat consists of far more than vitamins, proteins, fats, starches, and carbohydrates. It is through that food that we get all of the minerals and other substances that our enzymes and hormones and other organelles need both as building materials and, most importantly, as tools to do their work which is so critical for us to be able to function. Without those materials those enzymes cannot function. The body may still be able to generate the enzymes (the instructions for doing so are still contained in the DNA) but without their catalysts they are as productively useless as the workers sitting in the cafeteria. Going full circle, all of those catalytic minerals come to us through our food from the soil in which plants grow.

How do plants get those minerals out of the soil? That is done with the help of an army of microorganisms that convert them into a form, very often an oxide, that the plant can use and making them available to the roots of the plant. Our ability to function is dependent on those tiny organisms converting the minerals present in minute quantities in the soil into a form plants, and subsequently our own bodies, can use.

We are systematically destroying the microorganisms in this planet's soil upon which all land-based life is dependent and the overall fertility of that soil. We are doing so through our use of insecticides and pesticides in our agriculture which kills those soil organisms as well as the insects and other pests that we intend to destroy. We are doing so through our intensive deforestation of the planet which results in millions of tons of critical top soil (and the microorganisms and minerals in that soil) being washed out to sea. We are doing so by exposing to the sun and the higher volatility of their aerial environment forest soil micro-organisms that break down dead and fallen material on the forest floor to construct new soil. We are doing so through our intensive use of irrigation which leaches the vital mineral content of that soil down through the soil to levels where it is no longer accessible. We are doing so with our atmospheric pollution which results in poisonous chemicals being absorbed into the soil which is killing those microorganisms. We are doing so with our industrial scale plowing and tilling of the soil which results in millions of tons of top soil being dried up and blown away every year. We are doing so with our plowing also in the creation of an impermeable layer of hardpan just below the top layer of soil which prevents both plant roots and soil microorganisms reaching the mineral nutrients in the subsoil. We are doing so in turning over the soil with the plow which brings deep topsoil organisms to the surface where they are killed by exposure and driving microorganisms from the top layer of soil deeper underground where they are killed for lack of air and water and heat from sunlight. We are doing so with our systematic destruction of the balance of soil nutrients through our continued application of artificial fertilizers containing only nitrogen, potassium and phosphorus. We are doing so by systematically changing the ph levels of the soil through all of the above activities which makes it an inhospitable environment for many of these critical soil organisms. We are doing so by systematically changing the symbiotic relationships of soil organisms and plants by destroying the native variety of plants and replacing it with massive tracts of monoculture.

And there are myriad other ways in which our activity is destroying soil organisms and soil minerals which are the keys to the life-support capability of this planet's soils.

All life on this planet is critically dependent on the role of enzymes: life is far more process than substance. Without those enzymes life exists in substance only. Most of the enzymes that control the metabolic, maintenance and support processes in living organisms are critically dependent upon trace amounts of a wide variety of minerals and other chemical elements that those organisms obtain through their food. The availability of those minerals and other chemical elements in that food is critically dependent upon the organisms in the soil that convert them from their raw form into a bio-available form that those other living organisms can use. All life on this planet, therefore, is dependent upon those microorganisms that make those elements available. Much of our human activity is systematically destroying these vital microorganisms and, therefore, the life-support capability of the planet. End of story.

Clearly we cannot continue to destroy the life-support capability of this planet upon which we, and all other terrestrial life, depend for our existence. We must make drastic changes in the methods through which we are doing so, and we must begin to do so now, before it is too late. Sooner or later the effects of our systematic destruction of the planet's life support system will push that system to a tipping point beyond which recovery is not possible. We clearly do not know where or when that tipping point will be. We can only hope that we have not already passed it but we must still proceed with the assumption we have not.

The focus of our effort as we proceed forward must be food security. Our present human population is more than six times greater than most population biologists would agree the earth can support without benefit of fossil fuels. That population level, unfortunately, is dependent upon the very processes that are destroying the life support capability of the planet. At the same time as those processes are allowing us a massive population overshoot and a population that continues to increase it is seriously degrading the life-support capability that population requires. The criticality of our overshoot increases every day.

A most critical aspect of our future food security-our ability to feed our massive population-is soil fertility. We must ensure that the balance of the mineral and other elemental content of our soils is rebuilt and maintained and we must ensure that the soils are well repopulated and maintained with the critical microorganisms that convert those elements and make them available to the other living organisms of this planet, including ourselves.

We cannot use the processes that allow us to feed our massive population and destroy the planet's life-support capability and at the same time help the planet regain it's optimum life-support capability. The two are mutually exclusive. The longer we use those destructive processes in trying to maintain our existing population levels, or larger, the greater the risk we will push the planet's life-support system beyond the tipping point leading to its eventual and inevitable collapse. If we pass that tipping point the worst-case scenarios of population collapse become increasingly probable. The global population will inevitably contract, with or without peak oil, with or without global warming or any of the other global crises looming on the horizon. When and how badly depends upon how soon and how seriously we begin to rectify the problems we have created and move toward a sustainable modality of interfacing with this planet's natural systems.

–  Richard Embleton