LECTURE 2: THE BIOSPHERE

· If you think of the Earth as an egg, the inhabitable part is thinner, proportionally, than the shell of an egg.

· This should help you appreciate how tenuous is the hold of life on this planet.

· Then think of this; this is the only planet of its sort that we know of anywhere, so there’s no place to go if we mess up here.

· We are part of this fragile envelope of gases, chemical elements, and light traveling through cold, sterile space. Quite a miracle really.

· What interests us in this course is not any one thing in particular any one characteristic of that thing, but the interactions between living things and the physical environment; what we take in, what we put back.

· In particular, of course, we are interested in ourselves, the human part of the biosphere. That’s ok as long as we realize we do not exist in isolation from all the other parts. We often behave as though we do. Well, we don’t.

· We are made up from the same atoms and molecules as everything else, just organized differently. We borrow them while we are here (and they belonged to someone else once), and during our lives we replace virtually every molecule though the overall plan keeps it looking roughly similar.

· When our lease is up, we hand it all back to the ecosystem in one form or another (heat, ash, decomposition) for someone else to use, unless we mess it all up in the meantime.

· Another thing to remember, is that all this took a long time to come about. It took millions of years for the molecules of long-dead sea creatures to arrange themselves into hydrocarbons, or for the tropical forests to become carbon-rich coal. It takes us but an instant to burn it and release that energy which has been lying around since the Carboniferous period (when dinosaurs roamed.

· This thin envelope is limited at its upper level by the outer edge of the stratosphere¾and we can get there in minutes in a shuttle. Just think, if you climb Everest (29,000’ about 5 miles) you would be unable to breathe without contained oxygen. The depth of usable soil may be only a few feet and then we are into rock. We extract oil and other minerals from several miles down, but that is it. Most of the globe we cannot inhabit because it is water.

· Within this relatively tiny area humans have proved about the most versatile of all species because of their ability to modify their environment (tropical forests, Antarctica).

· Largely because of climate differences, or altitude, the assembly of natural conditions across the globe varies.

· We may divide the globe into a series of broad ecological regions called biomes within which the conditions are broadly similar though there are many local variations.

· Driving everything is the sun, which from our point of view is a constant source of energy. The intensity of this energy varies from place to place on the globe:

because the Earth is round

because it is tilted on its axis as it moves around the sun

· If the sun’s light simply struck the Earth in an unaltered state it would cause us to die. Our atmosphere acts as a filter taking out harmful ultra-violet radiation. This is in peril now because of the damage to the ozone layer which is the filter (like a sort of sun screen really).

· Then, again, the energy strikes the globe unevenly and would make most of the surface uninhabitable if it was not distributed by massive movements of air and water.

· After all this, we get to use¾directly or indirectly¾only about 1% of the available energy striking the Earth (at which point well over 80% has already gone!)

· So it seems hard for us to talk about an energy crisis when so much seems to be “wasted.” The problem is that we are, as yet unable to harness or use that which escapes

· Instead we fall back on using energy from the sun which came to Earth millions of years ago and is trapped in mineral form.

· So we have energy, and we have a screening atmosphere that protects us, distributes the warmth around, and keeps us within a relatively narrow range of temperatures conducive to our life form.

· The atmosphere also provides us with the elements we need for respiration, and which are needed for respiration by all other forms of terrestrial life. The balance of these elements, such as nitrogen, and oxygen are maintained by a delicate balance between animal life (excluding CO₂) and plants (including oceanic algae) which take in CO₂ and put out oxygen.

· So, if you mess up the plant life by, for instance, destroying the forests, or mess up the oceans so that the conditions at the interface change, then we may expect changes in the atmosphere which will do us no good at all.

· This is what we meant when we said we are interested in interrelationships: how things relate one to the other. These days we have to be interested in this on a global scale.

· Now it is true, to some extent, that the globe can adjust to changed conditions, so that more CO₂ may encourage more luxuriant plant growth producing more oxygen, but these changes are not guaranteed to be in our favor.

The Biosphere

Or

The “Sphere of Life”

The Biosphere: Life and Life Support

What is the Biosphere

Literally, it means the “sphere of life,” and it is the zone in which life exists, and¾to the best of our knowledge¾nowhere else.

The biosphere is that thin envelope of gas, water, soil, within which life evolved, and which organic life, as we know it, helps sustain. It is cyclical and interdependent.

Through this moves energy, which drives the whole thing and makes life possible.

I

t is important to remember that living things did not evolve because of the physical conditions on earth. The conditions to support life on Earth, as we know it, evolved along with life. They help to sustain us, and we (meaning all organic life) help to sustain them. So the life-support system is Interactive not unidirectional

The Biosphere: Life and Life Support

To gain a real understanding of Nature, insofar as that is possible, we must examine two important things:

First, are the elements of nature, or the component parts, such as soil, climate, the great cycles, etc., and we do this by “dividing up Nature” into its component parts, like chemistry, soil-science, physics, biology, botany, zoology, etc., etc …

Second, and just as important, we have to take all these artificially divided “bits” of knowledge, and then look very carefully at the process that unites all these parts and makes them function as systems.

Energy and life in the biosphere

· All life depends on energy, and all energy comes from the sun, but may be temporarily stored (e.g. in us, in food, in oil)

· Some energy is used directly, by plants for instance, other indirectly, as when we eat food—so energy comes in many forms. Energy is the fuel of life

· Some of these forms are deadly—ultra violet

· The interaction of all the energy-using life forms produces a “life-support system” that uses, reuses (food chain) and cycles this energy along definite pathways

· The energy also maintains a fairly constant range of temperatures within which we have evolved (in part maintained by the composition of the atmosphere). However, we have learned to insulate ourselves increasingly by conserving, or moving, energy

T

o put the broad argument into context, you are a highly organized, preplanned, integrated system for using energy to make this system (you) work, and rebuild itself over a limited time. During this time the machine is designed to reproduce itself, by combination with another similar, but not identical machine, to allow for any subtleties of energy availability that might have occurred since the first machine (you) was put together, thus constantly modifying the combination of matter that constitutes the organism and allowing for constant adjustments of efficiency..

We talked last time about Reality, and how we define that by our size, lifespan, knowledge, sensory abilities etc. It is the same with the environment: for most of history we were concerned about its usefulness¾growing food, providing fuel, growing building materials, yielding metals etc., etc. Remember how we defined plants as weeds? It was on the basis of their lack of usefulness, or their interference in what we decide Nature should look like (e.g. a lawn).

So we tend to define the environment more in terms of its service to us¾which is not surprising, even though that service might be that we have decided it looks “beautiful” and should be preserved. The result of this is that we have a short-term, utilitarian view of Nature (“resources”) that does not always mesh with the laws of Nature, or even the long-term interest of people. You could argue this is irrational?

The Biosphere: Life and Life Support

From our personal perspective in the west, and in the Judeo-Christian tradition, the organic matter in the biosphere exists in a hierarchy, so that we are set above the “beasts of the field, and the birds of the air.” So we have come to accept the idea of mastery over Nature. However, other faiths stress unity in Nature, not a confrontation with it. The Native American, and Zen religions, for instance, stress this. This is more in keeping with the harmony of the ecosystem, stressing balance, not domination, cycling, rather than “passing through.”

Thinking of ourselves and our car as a system for a moment, consider these system-operation characteristics in terms of your life and your automobile. What do we call these phenomena?

E Energy balance breaks down (several aspects to this)

E Machine ceases to be able to process energy throughput completely

E The fuel has to be converted into various useful elements by burning

E Surplus heat and toxic gases have to be removed

E The feedback mechanism that tells us that something is wrong with the functioning of the machine.

E You are using energy faster than it can be supplied.

Key Terms

BIOSPHERE

CYCLICAL AND INTERDEPENDENT

JUDEO-CHRISTIAN TRADITION

HARMONY AND BALANCE

ELEMENTS AND PROCESS

FUNCTIONING SYSTEMS

CHANNELING AND STORING

ENERGY

FOOD CHAINS

USEFUL ENERGY

CYCLES AND RECYCLING

POLLUTION