Laboratory Earth

PREFACE

It’s a cliché, I suppose, to assert that by the time you can finally afford to purchase or accomplish some urgent dream of youth, you no longer crave it. Clearly, our perspectives change with time. In my school years, weeks of dread preceded an assignment to write a “long” paper of some twenty pages. Decades later, this ink-stained veteran of perhaps twenty thousand pages faced months of a greater anxiety: trying to cram the essence of the very complex science, technology, and policy controversies surrounding the subject of global environmental change into a “short” book of some hundred and fifty pages.

I am indebted to my agent, John Brockman, not only for reminding me that such an exercise in brevity increases the reach of one’s ideas, but for creating the Science Masters series, which allows people an opportunity to be introduced in moderate depth to the substance and implications of the critical scientific issues of the day. Trading off content and context, scientific issues against policy controversies, and third-person reporting versus first-person advocacy—all in an accessible, compact package—was a major challenge. Of necessity, compromises were made; but a number of endnotes and additional readings are offered for each chapter (including some of my own writings, so that any reader who may want to hear me defend in more detail some of the things asserted in these pages has citations to pursue).

Despite a valiant effort, my early drafts were too long and sometimes too diffuse. Editorial comments and scientific critiques from Jerry Lyons, Jacques Grinevald, Stuart Pimm, Russell Burke, Larry Goulder, and Richard Manning were helpful in pointing out such problems. And I am grateful to the science writer Joel Shurkin for agreeing to take up the editorial surgeon’s knife. After his (occasionally painful but) skillful operation, the readers have the benefit of a more logically organized, compact, and accessible work. I appreciate the perspectives on the human psyche I gained from Sharon Conarton, since I firmly believe that it will be difficult to solve dimly perceived global problems when too many of us are steeped in too much personal denial. I also wish to thank Debra Sacks for efficient word processing of several drafts and cheerful accommodation to demanding deadlines at several stages, and Katerina Kivel for editing.

My children, Rebecca and Adam, had to deal with a father who often would appear at breakfast bleary-eyed from late hours of writing and editing, only to be reminded by them that I had insisted only hours before that they get a good night’s sleep to keep healthy and alert; somehow this intrepid author/father had strangely missed his own advice. Their support of my absorption in this project is lovingly accepted. And for Terry Root, my partner in both professional and personal spheres of life, I appreciated her timely and credible perspectives when my judgments were squeezed from too much internal pressure. Even more so, I am grateful for her choice not to add external pressure when I was recharging and perhaps looking to be nudged out of idling. We need the freedom to accomplish our art at the pace we negotiate with ourselves, and that insight she helped to reveal. In any case, this book is the product of that process. It is offered in the hope that at least some readers will be motivated to pursue their knowledge of the Earth much further, and that nearly all will resolve to get involved in being part of the solution to Earth system problems.

INTRODUCTION

IT’S A MATTER OF SCALE

Remember the famous photographs the astronauts took in space in the late 1960s that transformed global consciousness about the Earth? White clouds swirled around a blue globe with white ice caps and reddish deserts. The spiral patterns of storms stood out as bold features occupying regions the size of the New England states—1,000 kilometers or so in scale. That’s one way of looking at the atmosphere. An airplane passenger on a turbulent flight might think the atmospheric action is at the scale of hundreds of meters as the plane is tossed about in the sky. A balloonist who can see individual rain droplets or snowflakes leisurely drift by might conclude that the atmosphere must be understood at the microscale of millimeters. These observations are all “right” in a sense. It depends on what you are looking for, or at.

We might look up at a stormy sky, for example, and see clouds drifting from east to west. Does that mean the storm overhead is moving from east to west? Suppose the satellite map on the weather news that evening on TV shows us that although the local winds circulating at that instant were indeed moving from east to west, the overall storm was actually moving from west to east? There was nothing wrong with our local observations, just with our larger-scale hypothesis. We needed a bigger picture to get the large-scale relationships right. Or, as the mathematical ecologist Simon Levin of Princeton University once put it, the world looks very different, depending on the size of the window you are looking through.¹

The problem of seeing the world at one scale and extrapolating that observation to make judgments at other scales is at the root of more unnecessary contention than just about any practice I can think of—in interpersonal relationships as much as in arcane scientific debates.²

Nature shows amazing richness in its range of spatial scales and their interactions over what phenomena occur. Richness occurs over a range of time scales as well. You know from experience that winds blow and oceans flow, but those aren’t the only parts of the Earth that are dynamic. Our “solid” Earth is not solid, not forever fixed on the map in space and time. In fact, the land moves about, in response to natural forces. The drift of continents, we’ll see later, can have a major influence on the climate and on life.

Except for local phenomena like earthquakes or landslides or glaciers, whose motions are observable in human time frames, the time scales for major, continental-scale Earth motions are thousands to millions of years. It took special tools and creative insights to see these motions. How the “solid” Earth interacts with air, water, and life is important for understanding the Earth as a system.

Knowledge of cloud microphysics, even in great depth, will not by itself provide much context about the behavior of the Earth’s weather machine as viewable from space at large scales. So at what scale should we focus our discussions of weather, climate, ecology, society, and environmental change?

Our own experience isn’t enough—our personal scale is too limited—to see the full range of important phenomena in nature. We need the observations and inferences of a larger community—Earth system scientists, in this example—to open our perceptual window to the rich variety of nature that surrounds us.

CONTENT WITH CONTEXT

There has long been a fundamental tension among those who argue that without in-depth study our analyses will be shallow. Indeed, specialization has marked both academic and economic success stories since the Industrial Revolution. But, increasingly, there are those who say that without some sense of the broad context of real problems, disciplinary specialization may not provide what is needed to understand or solve pressing issues. To me, it is not sensible to debate for long whether it is worse to approach real problems only from the narrow, but deep, purview or to deemphasize sharply focused depth and instead stress integration across specialized disciplines. (The latter sometimes imposes career risks for interdisciplinarians, since problem solving often means fashioning originality at the intersection of disciplines, with not enough disciplinary originality to constitute a “respectable” contribution in that narrow specialty.) Despite the passion on both sides, content versus context (or large scale versus small scale) is a foolish, false dichotomy. The world obviously needs both large- and small-scale views with enough content to avoid being superficial, blended with sufficient context to address demanding, real-world problems.

Although space limitations prevent me from discussing here all relevant fields in the depth that a specialized account would demand, I will explore a wide range of environmentally relevant topics in sufficient detail to explain much of what is known about climate change and its ecological and societal implications. I will also identify what is speculative about climate change in the overall environmental debate. I’ll use the context of practical environmental and economic trade-offs to help guide the selection of a representative set of content areas.

Awareness that pollution can degrade our environment is hardly new. That was dramatically learned centuries ago in the era of uncontrolled coal burning that fueled the infamous London smogs. Centuries earlier, soil erosion on denuded hillsides in Asia taught a painful lesson of the need to farm or deforest with careful conservation practices. But these early lessons had two characteristics: they were discovered at local or regional scales, and they were learned after the fact—once the damage was apparent. The twenty-first century environmental problems are unique because the scale is truly global rather than simply local to regional. Even more serious, potentially long-lasting, even irreversible, effects are quite possible, thus it is no longer acceptable simply to learn by doing. When the laboratory is the Earth, we need to anticipate the outcome of our global-scale experiments before we perform them. At least that is the rationale undergirding the Earth systems science we’ll explore here.

The planetary-scale environmental issues I’ll address in these pages have come to be called “global change.” That phrase was invented by people who study the Earth as a whole system, to refer to the changes on a global scale that affect Earth systems (physical, biological, and social) that are interconnected and for which humans have some role in effecting those changes. Why study continental drift as part of “global change,” since humans are certainly not able to make continents drift? Because if we don’t understand how drifting continents affect the gases in the atmosphere, the climate, or biological evolution, then we won’t have the background knowledge necessary to forecast credibly so-called anthropogenic (that is, human-induced) sets of global changes.

I’ll touch on knowledge from traditional academic disciplines such as geology, ecology, atmospheric science, biology, energy technology, chemistry, agronomy, oceanography, political science, economics, and even psychology.³ I’ll also be looking at how humans are disturbing various components of the planetary system. In the course of the book a number of Earth systems science questions will be addressed:

   •  How long did it take for the climate and life to evolve this far?

   •  How does the Earth work as a coupled set of subsystems that includes living and nonliving parts?

   •  How are people disturbing the Earth system?

   •  What have we learned from the workings of the natural system that can help us forecast how human disturbances might affect it?

   •  What are some of the trade-offs between environmental protection and economic development, and how can both sets of these seemingly conflicting interests be reconciled?

THE WHOLE MAY BE WORSE THAN THE SUM OF ITS PARTS

One of the most potentially serious global change problems is the combined or synergistic effects of habitat fragmentation and climate change. People fragment natural habitats for farmland, settlements, mines, or other development activities. If the climate changes, individual species of plants and animals will be forced to adjust if they can, as they have in the past.⁴

Typically, they’ll migrate, as spruce trees did when the last ice age waned some ten thousand years ago. But the landscape has changed dramatically since then. Could all the migrating species that survived the ice age make it across the freeways, agricultural zones, industrial parks, military bases, and cities of the twenty-first century? Good science is necessary to help answer how such biological conservation practices can take place in the most economically efficient or politically practical ways. Global change science will involve looking at these kinds of questions. To answer them, we need to go to academic disciplines and ask, What knowledge do you have? The two most important questions to ask specialists, whether medical doctors or Earth system scientists, are simply: What can happen? and What are the odds of it happening?

The Earth systems scientist tries to integrate the information from many disciplines in an original synthesis that addresses real problems at the scales at which they occur.

WE HAVE MET THE ENEMY

People rarely intend to create environmental problems (illegal toxic-waste dumping and igniting the oil fields of an invaded country being some exceptions). Rather, most environmental ills simply emerge inadvertently from the sum of myriad, seemingly minuscule individual actions occurring at small scales, but around the globe. Whether by accident or design, the locally poisoned fish or globally altered climate is, nonetheless, damaged. Motive is irrelevant to environmental impacts. It applies only to dealing with the aftermath. Much of what we do to the environment is an experiment with Planet Earth, whether we intend it to be or not. It is everyone’s job to make the unintended potential consequences of our behavior conscious—even if ignorance or denial is the politically simpler “solution.” As the Stanford University population biologist Paul Ehrlich once quipped: “Ignorance of the laws of nature is no excuse.”

THE HUMAN DIMENSION

Causes of global-scale environmental degradations are most often ascribed to increasing numbers of people demanding higher standards of living and using technology or practices that pollute or fragment the landscape. There is an equation for this, formulated in 1971 by Paul Ehrlich and the then University of California at Berkeley energy analyst John Holdren: I = PAT.⁵ That is, environmental impact (I) equals population (P) times affluence per capita (A) times technology used (T).

When an observer abandons the large or global scale and looks instead at local environmental problems, these three factors may not be seen as easily. Different factors are identifiable at different scales. When viewed at the local level, you may find that corrupt officials or unaccountable industries stand out as prime causes of environmental problems. At larger scales, the problem may appear to be increasing use of land or energy and burgeoning populations.

I said we cannot avoid the human dimensions of global change if our analyses are to be useful. Some nations are economically better off than others, and more economic equity is a driving force in economic planning in the less developed nations. Tensions erupt between nations when it is asserted that those plans could threaten the global environment. At a local level, taxes on polluting fuels are an incentive for conservation and the development or deployment of cleaner alternatives. But taxes raise the price of energy, which has a greater impact on poor people than wealthy ones. People facing economic hardships usually have their priorities focused on economic growth more than on environmental protection. Such environment/development or equity/efficiency trade-off issues are already in the news and will lead to major debates in the decades ahead. So too is the problem known as “intergenerational equity”: The desire for economic progress today, and the wish to leave our heirs richer than ourselves, may boomerang and leave a legacy of environmental problems to later generations who cannot participate in today’s decision making.

There are between five and one half and six billion people in the world today, with one billion living on the margins of nutritional deprivation and tens of millions who die every year from preventable illnesses related to malnutrition. These people demand and deserve improved standards of living, but decisions made to satisfy that right cannot be just if they ignore the effects on the Earth. Even the grounds on which these debates are being held is disputed. The social scientists Robin Cantor and Steve Rayner noted that, like other human value conflicts, “the environmental debates can be understood in the context of people invoking different mythologies of the workings of nature to support their various political and moral beliefs.”⁶ Thus, natural and social sciences need to be blended with humanistic studies to fully illuminate the value dimensions of environment/development dilemmas. As we increase our understanding of the systems that control Earth’s environment, the myriad interconnections and potential solutions will crystallize.

I will discuss both the local problems and their impact on the global environment and global problems, which can in fact affect the local environment. Studying the environment fascinates because everything is linked to everything else in the system we call Earth, and while the connections among variables can be subtle, the effects sometimes are all too obvious. We obviously don’t know all the answers yet—and not even all the important questions! It will take interdisciplinary teams many decades to adequately assess the science and management problems of global change. But a great deal is already known, and much can be done to reduce risks.⁷ An informed public with the scientific knowledge and political will to make a difference can deal with many of the difficult questions that confront us. It is to that end that this book is dedicated.

But before we can peer into the shadowy future of climate and life, it is essential to journey back to our biogeographical roots: the Archean era of the distant past, when a young Earth was first beginning to nourish life.

CHAPTER 1

THE ORGANIC AND NONLIVING EARTH: A DYNAMIC COHESION

I doubt there is an earth scientist alive who wouldn’t jump at the chance for a trip on a time machine, to clock and measure the changes that naturally occurred on Earth eons ago. The scientist could move across the millennia, watching the plates on which continents ride slide across the surface of the Earth, altering not only their positions and the atmospheric composition but the biological life they carry as passengers. The scientist could monitor changes in the air, land, and waters that influence the evolution of life and, with proper attention, could detect how life, in turn, changed the character of air, land, and waters. The organic and the inorganic are connected: geochemistry and biology, geology and climatology. In time-machine scale, everything is in motion, constantly changing, like a giant, intricate, and evolving web of living and inanimate parts that together form a dynamic cohesion. But this pattern is not easily grasped by an observer without benefit of this marvel of fiction, unless she or he is part of a community of the curious using refined methods to reveal the immense patterns that emerge across the eons. That community and its methods are, of course, what today we call Earth systems science.

This dynamism plays out over geological time, an almost unimaginable span in which a thousand years is a wink. It usually takes many such winks to attract a geologist’s attention. The character in H. G. Wells’s The Time Machine could see the evolution of civilization over centuries; a biologist or geologist or climatologist in a sturdier device traveling back over a far longer period could watch the evolution of organisms and their interrelationship with the Earth they inhabit.

One period especially interesting to visit would be the era of the dawn of life, some 3.5 billion years ago, during the so-called Archean Age. We might be able to solve a sovereign scientific mystery that not only encapsulates Earth systems science but is at the core of the modern debate over global warming and the dangers of some of our unintended experiments with our world. What would we find there?

We would likely see a sun rising behind clouds in the sky, tall, smoking volcanoes, and sea waves lapping onto a treeless, grassless, barren plain. Strange-looking, meter-wide, mushroomlike rocks stand at the shoreline. We dare not venture outside our time machine without eye and skin protection because of dangerously high levels of ultraviolet radiation, levels high enough to threaten the long-term survival of any known life forms on land or in the air. We also must wear oxygen masks, for the atmosphere is composed primarily of carbon dioxide. There is some oxygen, but at only a billionth or so of the levels we know today.

The air temperature is hot—38°C (100°F)—but the noonday sun somehow appears dimmer and slightly smaller than the one we’re used to back in the Holocene interglacial, our time. Solar panels outside our time machine read about 600 watts of incoming energy, about 25 percent less than the power we now receive from the sun. Three and a half billion years ago, the sun is smaller than our sun.

But why? When nuclear physics is applied to solar processes, it suggests that our star, like most of its type, grew fatter and brighter as its thermonuclear reactors converted hydrogen to helium. Most scientists believe that the solar luminosity has increased about 30 percent since the formation of the Earth some 4.5 billion years ago, 5 percent of that in the past 600 million years. This was the era of rapid biological evolution that left its indelible fossil footprints in the rocks we dig up today.

A SUPER GREENHOUSE EFFECT

Most climatologists would unhesitatingly say that a cut in solar heat input to the Earth by some 25 percent today would plunge us into a deep freeze. But the Archean was apparently warm, not frozen—remember, the outdoor thermometer of our time machine read a toasty 38°C.

This dilemma is popularly known as the “faint early sun paradox.” In 1970, Carl Sagan and George Mullen, at Cornell University, proposed one solution to the paradox: a super greenhouse effect.¹ They suggested that two gases, methane and ammonia, are very effective at trapping infrared radiation in the lower part of the Earth’s atmosphere, and that these may have been present in sufficient abundance in the Archean to make up for the solar deficit and keep the climate temperate.

Critics called their idea fanciful, arguing that these gases are highly reactive, have short lifetimes in the atmosphere, and therefore need to be continuously replenished (presumably by life). If so, how could methane and ammonia have been present in large enough concentrations to make the Earth warm enough to get life going? We don’t know—one reason why that time machine is such an attractive fantasy for the Earth-curious.

This issue of whether methane (CH₄) and ammonia (NH₃) were produced by biological processes or by processes that had nothing to do with biological forms in the Archean era is still unresolved, but Sagan’s and Mullen’s basic idea is accepted by most scientists. However, today’s variant suggests that carbon dioxide (CO₂) may have been the main super greenhouse gas, rather than CH₄ or NH₃. The shadow of this theory looms over us today. If such a phenomenon occurred in the Archean time, couldn’t it happen again?

To answer that crucial question, we have to be cognizant of the processes that affect the composition and structure of the atmosphere.²

In science, increased understanding does not always mean increased certainty, at least at first. The solution to one problem frequently raises another problem. In this case: If some hundred times greater than present concentrations of CO₂ kept the Archean balmy, what happened to keep the climate from dramatically overheating during the next 3 billion years as the sun brightened by 25 percent or so?