Earth

A Tenant's Manual

Frank H. T. Rhodes

• Publisher: Cornell University Press
• Year: 2012
• ISBN:
  9780801466205
• Topic: Sciences biologiques
• Subtopic: Conservation et Protection de l'Envronnement

"It's impossible to grasp the whole planet or integrate all the descriptions of it. But because we live here, we have to try. This is not just an artistic compulsion or an existential yearning, still less an academic exercise. It's a survival issue. This is the only planet we have. We're stuck here, and we don't own the place—it would be the height of arrogance to assume that we do. We're tenants here, not owners, but we're tenants with hope for a long-term tenancy. We want to extend our lease just as far as we can."—from Earth: A Tenant's Manual

In Earth: A Tenant's Manual, the distinguished geologist Frank H. T. Rhodes, President Emeritus of Cornell University, provides a sweeping, accessible, and deeply informed guide to the home we all share, showing us how we might best preserve the Earth's livability for ourselves and future generations.

Rhodes begins by setting the scene for our active planet and explaining how its location and composition determine how the Earth works and why it teems with life. He emphasizes the changes that are of concern to us today, from earthquakes to climate change and the clashes over the energy resources needed for the Earth's exploding population. He concludes with an extended exploration of humanity's prospects on a complex, protean, and ultimately finite world.

It is not a question of whether the planet is sustainable; the challenge facing life on Earth—and the life of the Earth—is whether an expanding and high-consumption species like ours is sustainable. Only new resources, new priorities, new policies and, most of all, new knowledge, can reverse the damage that humanity is doing to our home—and ourselves. A sustainable human future, Rhodes concludes in this eloquent, sobering, but ultimately optimistic book, will require a sense of responsible stewardship, for we are not owners of this planet; we are tenants.

Surveying the systems, large and small, that govern Earth's processes and influence its changes, Rhodes addresses the negative consequences of human activities for the health of its regulatory systems but offers practical suggestions as to how we might effect repairs, or at least limit further damage to our home.

CHAPTER 1

The Third Planet

Suppose, just suppose, you were somewhere out in space, beyond the confines of the solar system, and that you were in radio contact with an alien, a friendly alien, from another part of the galaxy. And suppose, just suppose, that in chatting about things in general, you wanted to describe your home, the place where you live or had grown up. Not that small town in New Hampshire, or that particular suburb of Los Angeles or Cape Town or London, but the planet, Earth—the home planet. How would you identify it? How would you give some sense of where it is, what it is like, how it is to live there?

Well, you’d have to locate the Sun, our parent star, of course, and then relate the Earth to that. So, how do we locate, how do we describe the Sun? The Sun, as astronomers describe it, is a medium-sized, main sequence G2 star, one of more than a billion, perhaps as many as 250 billion, stars in our galaxy. There are other galaxies, too, of course. Perhaps hundreds of billions. And Earth is one of the dense, rocky, inner planets, the third planet out from the Sun, between the pale, cloud-draped Venus and that rather reddish planet, Mars. “But what’s it like to live on a tiny planet like that?” asks the alien. “If I were to go and live there, if I could travel there, what would I find? What kind of place is it?”

That could be a long conversation, because it’s a difficult question. It’s difficult because no two of us see Earth, or anything else for that matter, in quite the same way. Think of all the artists, poets, writers, composers, explorers, cartographers, landscape architects, urban planners, and more, and the endless richness and variety of their views, perceptions, and descriptions of Earth. And it’s difficult, too, because it’s impossible to see Earth “whole,” even from space. “My view of our planet was a glimpse of divinity,” declared the astronaut Edgar Mitchell. But most of us can’t see that. Scale and perspective limit us. Even if we took all the descriptions that have ever been written, or painted, or composed, thousands upon thousands of them, we’d still have trouble giving a truly comprehensive description, however well we know our own planet. Let me try to explain what I mean.

There is something comforting, something reassuring, about Earth. It is where we are from, the place where we grew up: our backyard, our street, our hometown, our state. It is the place we know, the place where our family and our friends live. It is the place where we work. Even the word Earth is somehow warm and familiar. It is the summer evening barbecue on the lawn; it is fall, with the glorious colors of the maple near the porch; it is Thanksgiving night with the family around the table, enjoying turkey and pumpkin pie; it is spring rain, with trillium under the new-leafed branches. It’s Earth. It’s home.

And it is not just my local neighborhood. It is the other places that we know so well. It’s the Merritt Parkway, it’s Fifth Avenue, it’s Yankee Stadium, it’s Rockefeller Plaza at Christmas, it’s summer on Nantucket, and it’s days on the beach. It’s taking the kids to camp by the lake in Ontario; it’s flying to Denver to visit the in-laws. It’s all that and more.

And just then the astronomer—a terrestrial astronomer—strolls by. “Earth, ah, yes, Earth,” he muses. “The fifth-largest planet of the solar system: third in order from the Sun, between Venus and Mars. It has a mean distance of about 93 million miles from the Sun. That’s about 150 million kilometers, by the way. It rotates from west to east, completing one rotation every day. Ah, but you know that, don’t you? Its diameter at the equator is 7,926 miles, and its circumference is about 24,830 miles. It’s a rocky planet, not gaseous like…”

“Rocky it certainly is,” interrupts the geologist. “Its mean density is about 5.5 grams/cm3, but here’s the remarkable thing. The average density of all the rocks we can measure at the surface is only 2.8. Quite remarkable, isn’t it? How do you account for that? Well, the deeper rocks must be much denser than the ones at the surface. In fact, the crust of the Earth, its outer shell, is very thin—well, comparatively thin. It ranges in thickness from five to twenty-five miles, and the continental areas are thicker, as well as higher, than the oceanic areas. Below the crust, the mantle consists…”

“What you omit,” interrupts the biologist, “is that Earth is the only planet known to support life. Lewis Thomas described it well: ‘Viewed from the distance of the moon, the astonishing thing about the earth, catching the breath, is that it is alive…. Aloft, floating free beneath the moist, gleaming membrane of bright blue sky, is the rising earth, the only exuberant thing in this part of the cosmos…. It has the organized, self-contained look of a live creature, full of information, marvelously skilled in handling the sun.’”1

“What you mechanistic merchants overlook is the splendor and beauty of this remarkable place,” interrupts the poet. “Remember what Wordsworth wrote:

There was a time when meadow, grove, and stream,

The earth, and every common sight,

To me did seem

Apparelled in celestial light,

The glory and the freshness of a dream.”2

“Wait, wait,” demands the environmental activist. “Measure it, analyze it, eulogize it if you will. But the most important thing people need to know about Earth is that we are abusing it, plundering it, polluting it, poisoning it, depleting it, destroying it. We’re squandering our heritage, defaulting on our tenancy, robbing our children. Every year thousands of acres of tropical forest are destroyed; every hour another species becomes extinct.”

“Now let’s not dramatize this. Let’s not overdo this doomsday scenario,” replies the solid citizen. “Climate change is nothing new. It’s been going on since the end of the last Ice Age. And a good thing, too. Without it, this would be a bleak and inhospitable place to live. As for depleting resources, global warming, rising sea level, and all that doomsday stuff…”

So each blind man, each specialist, touches the elephant Earth. We all do. We must. And we desperately need the knowledge that each one brings. The problem is that it is impossible to comprehend it all: it’s impossible to grasp the whole planet, to throw our intellectual arms around it or integrate all the descriptions of it.

But because we live here, we have to try. This is not just an artistic compulsion or an existential yearning, still less an academic exercise. It’s a survival issue. This is the only planet we have. There is no escape to Mars for us. We’re stuck here, and we don’t own the place—it would be the height of arrogance to assume that we do. We’re tenants here, not owners, but we’re tenants with hope for a long-term tenancy. We want to extend our lease just as far as we can.

That doesn’t mean we are intruders, or interlopers, of course. Our species has been here a long time, at least in human terms: about 130,000 years, in fact. Early tool-making hominids appeared about 2 million years ago. And as tenants we have rights, rights to peaceable occupancy, just as every lease explains. But tenants also have obligations as well as rights. It is our job to look after the property, to care for it, to safeguard it. It’s our job as tenants to be responsible occupants, careful custodians, good neighbors with the 7.0 billion other people with whom we share our tenancy, not to mention some 2 million known species of other animals and plants who share the property.

So we need some understanding about this remarkable planet we share. We need to be clear about the terms of our tenancy. We need to know something about the property itself, its location, its layout, and its boundaries. We need to know a little bit about its history, and we need as much information as we can possibly gather on how to take care of the place: how the plumbing works, how the heating system operates, and the longer-term outlook for our residence and our well-being here, as well as the prospects for our families and children.

And that’s an urgent discussion. The old Native American proverb is right: “We don’t inherit the Earth from our parents; we borrow it from our children.”

This book is intended to provide a kind of manual that will help us become knowledgeable and responsible tenants. It is a book that seeks to explore the property and get a glimpse of the wider neighborhood. It is an attempt to create a kind of mental map, not unlike those beautiful medieval navigation maps, which charted intricate coastlines and rivers, mountains and settlements, relationships and distances, winds and hazards, and guided our forebears across unknown seas. If we can create that kind of chart, we can have an informed discussion about our roles and responsibilities. For there are relationships that are subtle, trends that are complex, and hazards that are more threatening than medieval sea dragons.

Every one of the countless species that ever lived has contributed to the building of our planet. And every living species—bacteria, insects, flowers, trees, worms, fish, mammals—every living creature, influences this planet that we share together. But we, our species, influence it more than all the rest at the present time; we know that we influence it, and we begin to understand a little how we influence it. We can even choose, actually select, the way in which we wish to continue to influence it, for good or ill. So we are not just tenants, we are something more. We are stewards, custodians, caretakers, and “it is required of stewards that they be found faithful.”

Now suppose we grant all that. Suppose we agree we are not owners but tenants, with needs and rights as well as obligations. And let’s agree, too, that we have neighbors we care for, not only next door, but also beyond, to whom we have obligations. And we have families, too—parents, siblings, children, grandchildren—about whom we care, about whose future well-being we are deeply concerned. Grant all that. But still, we live on a small planet with finite resources, a burgeoning population, and stark inequalities in the distribution of wealth and resources. People of the developed world have an insatiable appetite for goods, services, food, energy, and raw materials, while more than 3.7 billion humans suffer from malnutrition.3 We live in a world where our long-term exploitation of the planet’s capital—soils, fossil fuels, metals, forests, and fisheries—may threaten not only to deplete but to exhaust some of our nonrenewable treasures, and certainly threatens to reduce the quality of the air we breathe, the soil we till, and the water we drink. We live in an age where much of the once widespread pastoral landscape, that “green and pleasant land,” has been lost to development and urbanization. We live at a time when the environmental impact of relentless population growth and industrialization of the past two centuries in the developed world is about to be reinforced by the far more rapid industrialization of the less developed world.

One doesn’t need to be an environmental zealot, or even a Green Party member, to see the widespread effects of global warming, of climate change, of rising sea level, of deforestation, of loss of arable land, of atmospheric pollution, of resource depletion. Continuing population growth multiplies all these problems. And the growing industrialization of the developing world multiplies and magnifies them even more.

All this sounds a little like Woody Allen: “More than any other time in history, mankind faces a crossroads. One path leads to despair and utter hopelessness. The other, to total extinction. Let us pray we have the wisdom to choose correctly.” And we might have to concede his point unless—and it’s a big unless—we can have a realistic assessment of where we stand and begin to think and talk and act together as tenants. No coherent planning, still less any global strategy or UN program, is likely to emerge until we can begin this informed discussion. That’s the starting place for this book.

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1. Lewis Thomas, The Lives of a Cell (New York: Bantam Books, 1975), 170.

2. William Wordsworth, “Ode: Intimations of Immortality from Recollections of Early Childhood,” The Complete Poetical Works of William Wordsworth (New York: Houghton Mifflin, 1919), 5:54.

3. D. Pimentel, “Ecological Footprint, World Population, and the Environment” (keynote paper presented at the International Ecological Footprint Conference, “Stepping Up the Pace: New Developments in Ecological Footprint Methodology, Policy and Practice,” BRASS Centre, Cardiff University, Wales, http://www.brass.cf.ac.uk/events/International_Ecological_Footprint_Conference-Keynote_Speeches.html).

CHAPTER 2

The Home Planet

Beating the Bounds

Though we know our neighborhood like the back of our hand, the Earth itself, the larger place that includes all our neighborhoods, is a strange place. This homestead, at once so stable, is spinning, we’re told, and spinning fast at about 1,000 miles per hour. This secure dwelling, this sturdy foundation, is also hurtling around the Sun at 66,600 miles per hour; that’s 18.5 miles per second.

It’s unsettling, contradictory, bewildering, even intimidating. So let’s step back and get a sense of our position. Just where are we? How can we get a useful sense of the place we call home?

There is, in some parts of Europe, an ancient ceremony known as “beating the bounds.” The ceremony has existed in Britain, for example, for well over two thousand years, and in earlier days it involved the inhabitants of a manor house, village, or parish marking property lines by walking the boundaries and beating certain boundary markers—trees, boulders, fences, hedges, and so on—with sticks.

The original purpose of this regular beating was perhaps to drive out evil spirits, but by Anglo-Saxon times it was used chiefly to assert the limits of the property and especially, in days before maps, to acquaint all the local inhabitants with the nature and extent of their land. At certain points, young boys were held upside down and beaten with wands or had their heads bumped on particular markers, presumably to emphasize the importance of the boundary line.

Beating the bounds defined the boundaries of the dwelling place. It also emphasized one more thing: it acknowledged the bounty of the land. It reminded tenants and serfs (and almost all the participants were either tenants or serfs) of their obligations and confirmed their rights. It united everyone in a sense of community, place, and dependence.

How do we define the boundaries and explore the limits of our global village today? How do we encourage that sense of place, of community, of responsibility? Well, perhaps by beating the bounds, just as our forebears did, marking the extent of this wonderful homeland of ours.

But, of course, there is more to the home planet than the Earth alone. Earth’s surface doesn’t mark our boundaries. There’s the atmosphere above it, extending some 350 miles above Earth’s surface. There are neighbors to consider: Venus, Mars, and others. There is the heating plant, our energy source for the whole property, our grandparent: the effulgent Sun. There’s our terrestrial daughter, the Moon, which creates the tides. There are “lights for signs” as the psalmist called them, stars for navigation and direction. There are bodies beyond the terrestrial boundary that influence our every turn and on whose benevolence our lives depend. We need to look around not only the Earth but also the larger neighborhood.

Even so, we are Earth creatures, and likely to remain so. So let’s start with Earth.

Measuring the Earth

On April 7, 2006, a British traveler was interrupted as he tried to cross the Russian border, where he was detained by immigration officials because his passport did not have the required visa stamp. What was remarkable was that the border was the one across the Bering Strait and that the traveler, Karl Bushby, an ex-paratrooper, was seeking to walk around the world. His journey had started in Chile and continued along the length of South America and North America to Alaska and then over the Bering Strait. He’d already walked eighteen thousand miles, about half the total distance of his planned journey, and had been walking since 1998. He hopes to complete the walk in 2014, so his walk around the Earth will have taken sixteen years. That’s how large the Earth really is.

Our ancient ancestors regarded the Earth as an object of veneration, but various cultures suggested several views as to its form. The Homeric-age Greeks regarded it as a flat disk, surrounded by a world ocean; the Egyptians as a broad surface, with the sky stretched as a canopy over supporting mountain ranges; the Hindu Vedas as a tree of knowledge; and the Brahmins as a mountainous land, resting on elephants, who stood on the shell of a giant turtle, in the middle of an encompassing sea. It was Pythagoras and later Plato in about 500 BC who suggested, on aesthetic grounds, that the Earth must be spherical. Aristotle, in the third century BC, confirmed this by arguing that it was demonstrated by the hulls of ships disappearing over the horizon being lost to view before the masts and also by the Earth’s curved shadow on the Moon during a lunar eclipse.

But it was left to another Greek, Eratosthenes, some years later, to measure the Earth. Eratosthenes was born in Cyrene, in what is now Libya, in about 276 BC. He was a man of extraordinary talent: poet, philosopher, administrator, mathematician, and astronomer; he headed the great library at Alexandria and invented the “sieve of Eratosthenes” for finding prime numbers. Eratosthenes was a prolific author, but he is best remembered as the one who made the first measurements of the circumference of the Earth.

Like several of his contemporaries, Eratosthenes reasoned that, because both the Sun and Moon were spherical, it was probable that the Earth, too, was spherical rather than flat. He had noted that at noon on Midsummer Day, the Sun shone vertically down a well at Syene (now Aswân in Egypt). He argued that, if the Sun were assumed to be so remote that its rays could be regarded as essentially parallel to one another, measurement of its angle of inclination (by means of the shadow of a vertical object) at another locality (Alexandria) and measurement of the distance between the two points could be used to calculate the circumference of the Earth. This he estimated (using reports from caravaneers who took fifty days to make the journey at a rate of one hundred stadia a day) to be 250,000 stadia, and, though there is some scholarly debate as to exactly how long a stadium was, this is interpreted as about 28,700 miles, a remarkably accurate result. Eratosthenes also calculated the inclination of the Earth’s axis with similar accuracy, as well as the distances to the Moon and the...