The Tree

by Colin Tudge

  Yet very simple arithmetic shows that the Western goal of urbanized industrialized life and the promise of limitless wealth for everyone cannot be realized. Raising everyone in the world to the material standards of the average lower-middle-class, middle-income American would require the resources of at least three earths. Furthermore, the means by which this dream is being imposed on the world (in the name of “freedom,” “democracy,” and “justice,” as well as “progress”) seem expressly designed to undermine the well-being of most of humanity. For most people in the world live and work in the countryside, at rural crafts of which the chief is farming. Industrialization simply puts them out of work. If India farmed the way the British and the Americans do, half a billion people would be unemployed—more than the total population of the newly expanded European Union and close to twice the population of the present United States. No other industry can employ so many people as farming can, and still does, and no other industry could conceivably be so sustained. Most of Africa is even more emphatically rural than India and has even fewer realistic options. Yet Westernization—urbanization, industrialization, and a monetarized economy geared to GDP—is promoted by the world’s most powerful governments as the universal algorithm for all of Africa, Asia, and South America: the formula that, once applied, will solve all our problems. Even worse, the formula is applied with all possible haste, for the world’s new economy is driven by the perceived need for “competition.” But untempered competition is a crude concept indeed, as any worthwhile moral philosopher would attest, and any truly modern biologist could ratify.

  The world needs a sea change. It isn’t just a question of changing our leaders’ minds, for that is too exhausting and we don’t have enough time. It isn’t a question of changing our leaders, for we are liable simply to land ourselves with more of the same. The world as a whole needs a different kind of governance, different kinds of people in charge. To ensure this, we (all of us, for it’s no use relying on the current leaders, who are doing well under the present system) must find new ways of ensuring that new kinds of people are elected and given real power: people who respond to the real, physical needs of the world, and to the needs of humanity at large. Present-day leaders—politicians and captains of industry—are wont to suggest that any radical initiative that takes account of the realities of soil, water, and climate is “unrealistic,” commonly because such initiatives may inhibit the plans of bullish industries and their governments, and hence inhibit “growth.” But the word “realistic” has been corrupted. It ought to apply to the realities that are inescapable—of physics, of biology—made manifest in the declining earth, and the creatures that live on it. It should apply to the realities of people’s lives—whether they have enough to eat, and water, and shelter; whether they have control over their own lives, and worthwhile jobs, and can live in dignity. The “reality” of which our current leaders speak is the reality of cash. But cash is not the reality. Cash is the abstraction.

  A sea change, to mix the metaphors, may seem pie-in-the-sky. In truth, however, and encouragingly, most of the big and necessary ideas are already in place, or already being worked upon. Excellent ecological studies are under way. Truly appropriate technologies, designed expressly to be sustainable—both low-tech and high-tech—are developing apace, and many (including many of the simplest) are quite wonderful. And, which is at least as necessary, many groups worldwide are working on new economic models that, though basically capitalist, are geared directly to human well-being, rather than to the gross abstraction of accumulating cash. Certainly, there can be no surefire formulas. We simply cannot tell, until we try, whether our ecological projections and economic plans will work out the way we want them to. But if we keep our eyes on the right targets—human well-being in a diverse world; humanity able to live well, effectively forever—then we are in with a chance. If we proceed with reasonable caution, we can correct mistakes as we go. If we simply apply the present-day algorithms—high tech applied willy-nilly wherever it will make the most money the most quickly—then, surely, we and the world as a whole have had our chips.

  Most important, the future endeavors of humanity must be geared to biological realities. The world’s economies (and the efforts of scientists and technologists) must serve those realities. Most obviously—once we start to think seriously about the fate of cities, and environmental stress in general, and human employment and dignity—we see that for the foreseeable future, and probably forever, the economies and physical structure of the world must be primarily agrarian. In the current, crude, unexamined dogma, “development” and “progress” mean urbanization. The prime requirement, in absolute contrast, is to make agrarian living agreeable. It can be. It’s just that at present, all the world’s most powerful forces are against it.

  Trees are right at the heart of all the necessary debates: ecological, social, economic, political, moral, religious. It isn’t the case that trees are always a good thing. The wrong tree in the wrong place can do immense damage: eucalypts can turn areas that are merely dry virtually into desert; willows may encroach on wetlands and change their character—turning habitats for ducks and frogs into woodland; over-lusty garden trees may undermine houses; mountain ash trees near arable fields may provide wintering grounds for aphids; flowering exotics in austere native landscapes are aesthetically vulgar and often useless to native wildlife; and so on. It isn’t true that everywhere in the world needs more trees. In some places, there could be too many—lowering water tables that are already too low. The wrong trees in the wrong places can poison rivers, undermine buildings, and even cause soil erosion. Yet beyond any doubt, most landscapes and the world in general would benefit from many, many more trees than there are now, and the wholesale squandering of present-day forest seems like an act of suicide.

  But it is also true—marvelously and encouragingly so—that societies can build their entire economies around trees: economies that are much better for people at large, and infinitely more sustainable, than anything we have at present. Trees could indeed stand at the heart of all the world’s economics and politics, just as they are at the center of all terrestrial ecology. The more I have become involved with trees in writing this book, the more I have realized that this is so. In the future of humanity, and of all the world in all its aspects, trees are key players.

  THE BIGGEST CHALLENGE OF ALL: CLIMATE

  The world’s climate has fluctuated spectacularly these past few billion years, often to fantastical extremes. At times the whole world has been tropical, with palm trees in Canada fringing the Arctic Ocean. At other times (long before the recent wave of ice ages) the entire surface may have frozen over. Beneath the streets of London—obligingly revealed by civil engineers during the past few hundred years—are fossils of crocodilians and of nipa palms, denizens of tropical rivers; but also of woolly mammoths, creatures of the tundra. Those who suppose, as some of the world’s leaders have chosen to do these past few decades, that the world is more or less bound to be the way it is now should look at the evidence all around of past deviations, or at least take notice of those who have.

  All kinds of evidence show that the fluctuations in temperature, from global tropical to global freezing and back again, are correlated with the concentration of carbon dioxide in the atmosphere. Some of the most convincing evidence comes from ancient ice in Greenland and Antarctica, which traps atmospheric gas from earliest times that can then be directly analyzed. When the concentration of carbon dioxide was high, the fossils show, the world was warm. When it was low, the world was obviously cool.

  The physics is simple. The earth is constantly warmed by sunlight, and constantly radiates the warmth away again. The solar energy coming in contains light of all wavelengths. The radiant heat that the earth gives out is all in the infrared spectrum. Carbon dioxide absorbs infrared. So atmospheric carbon dioxide filters out only a fraction of the solar energy coming in—a proportion of the infrared; but it traps a great deal of the energy g
oing out, since most of what’s going out is infrared. So more energy is kept in than is kept out, and the net effect is to warm the atmosphere. The glass in a greenhouse operates in the same way, so this is called the “greenhouse effect” and carbon dioxide is called a “greenhouse gas.” Some other gases also have a greenhouse effect, including nitrous oxide, methane, and water vapor. But carbon dioxide is the main variable.

  It may seem odd that carbon dioxide can have such an effect. After all, its concentration in the atmosphere is low. The present concentration of carbon dioxide in the atmosphere is only around 370 parts per million. Yet it has been calculated that if the atmosphere contained no carbon dioxide at all, the average surface temperature would fall to -18°C (0°F). At the time of the ice ages, atmospheric carbon dioxide was down to 190 to 200 parts per million; and it was indeed very cold. When plants first colonized land 400 million years ago, atmospheric carbon dioxide stood at around 7,000 parts per million—and the world was extremely warm. At the time when cyanobacteria first evolved photosynthesis, more than two billion years ago, the atmosphere contained no oxygen at all. Carbon dioxide was the chief gas of the atmosphere, apart from nitrogen. The world must then have been ridiculously hot. For creatures like us (or modern trees) the heat alone would have been lethal (let alone the noxiousness).

  Modern meteorological records, and the notebooks of gardeners and naturalists, show that the world has been getting warmer during the past 150 years or so. The Intergovernmental Panel on Climate Change (IPCC) reported in 2001 that the average temperature of the whole world increased by 0.6°C (1°F) between 1900 and 2000. Such a rise may not seem great, but ostensibly small changes averaged over the whole world can imply huge changes locally and regionally—enough to have profound effects on environments and people. The trend seems inexorably upward: 1998 was the warmest year since reliable records began; and the 1990s was the warmest decade.

  Changes in temperature cause changes in rainfall. Precipitation rises overall (since more water evaporates from the surface of the oceans), but the distribution is uneven; so some places become much wetter, others much drier. The IPCC noted an overall increase in precipitation (rain and/or snow) of 0.5 to 1 percent per decade through the twentieth century: up to 10 percent over the century. The increase was highest in the mid- and high latitudes of northern continents. In the tropics (10° north to 10° south) the increase was only 0.2 to 0.3 percent per decade, and in the northern subtropics (10° north to 30° north) rainfall actually lessened, by around 0.3 percent per decade. The subtropics are hugely important to humanity for our agricultural crops, our forests, and as places where people live. Drought in that latitudinal band is seriously bad news. In the Southern Hemisphere, which lacks a vast continental landmass and has vast oceans instead, there were no comparable changes—or at least the changes were not so regular.

  But overall averages are not all that matters. Extremes increased too—just as theory predicts must be the case, since the temperature of the world’s surface changes unevenly. More and more places recorded their hottest days in history. The late twentieth century saw some of the worst ever storms and hurricanes, floods, droughts, and forest fires. The Southern Hemisphere is hugely affected—one might say plagued—by El Niño, the warm current that flows from west to east across the Pacific every few years as a result of the southern oscillation. The western South Pacific warms up more than the eastern, and every so often the warm water in the west escapes and flows to the east. The El Niño current (so called because it tends to flow around Christmastime—Niño means “little boy” and refers to the Christ child) causes floods in some places, droughts in others, and also causes fish stocks to fail, with the consequent devastation of seabirds and potentially of local fisheries. El Niños seem to be getting more frequent and more severe.

  The changes in atmospheric carbon dioxide that caused huge climatic fluctuations in the deep past were brought about by natural events. In general, carbon in the earth’s surface takes the form of carbon dioxide that floats free in the atmosphere or is dissolved in the oceans. Or it is present as “organic” carbon, locked up in the bodies (including the dead bodies) of living creatures—flesh, leaf litter, and timber—and as carbonates, in rocks. Rainfall, volcanic action, and the movements of tectonic plates ensure that carbon flows between the four sources, changing chemically as it does so—from carbonate to carbon dioxide to flesh (plus dead leaves and timber) to carbon dioxide and back to carbonate.

  The general cooling over the past forty million years or so has apparently been caused by the (fairly) steady loss of carbon dioxide from the atmosphere; and this has been ascribed to the rise of the Himalayas and the Tibetan plateau, caused by the slow tectonic crunch of India into the south of Asia. The Tibetan plateau and the Himalayas are a huge mass of rock that interrupts the saturated winds that blow from the Pacific and thus causes the rains that manifest as the monsoons. This rain is steeped in atmospheric carbon dioxide, which reacts with the rocks of the Himalayas, then washes into the sea. Thus, carbon dioxide has been steadily leached from the atmosphere, and the world has cooled accordingly.

  But carbon dioxide has been rising again these past two hundred years or so—not from natural causes but mostly through the restless activity of humanity. Atmospheric carbon dioxide now stands at around 370 parts per million, but in 1750, at the start of the Western world’s industrial revolution, it was a mere 280 parts per million. The annual rise averages around 0.4 percent. Methane in the same period has risen by 151 percent, and nitrous oxide by 17 percent, and both continue to rise. By 2080, at the current rate of increase, carbon dioxide levels will be double present levels, around 750 parts per million. This will make the world between 1.4 and 5.8°C (2.5 and 10.4°F) warmer than it was in 1990, which will melt the polar ice caps (as is already happening) and increase sea levels by anywhere between 3.5 and 34 inches. The higher figure—the best part of a meter—would be enough to wipe out many a small island (and not a few major cities). The calculations are rough for all kinds of reasons—not least because more warmth means more clouds, and more clouds would be cooling, and so would have a negative feedback effect. But future changes in cloud cover are difficult to calculate.

  In recent years, too—in fact, since 2001—American meteorologists in particular have realized that over the past few decades the full effects of global warming have been masked by “global dimming.” It transpires that atmospheric pollution by particles—variations on a theme of soot—has been reducing the energy input from the sun by an astonishing 30 percent. The world, currently, is cleaning up the soot—which, technically, is fairly easy to do. Catalytic converters on cars do much of what is needed, and these are encouraged because they are big business, and their development and sale increases the GDP. But the world is not commensurately reducing its output of carbon dioxide. The Kyoto Protocol of 1997 was and is intended to reduce carbon dioxide output, or at least to ensure that whatever extra carbon dioxide is produced is mopped up. The protocol was not ratified until the beginning of 2005. The United States, by far the world’s biggest producer of industrial carbon dioxide, has not signed up to it. But the protocol would not go far enough, even if everyone did sign up and acted upon it. Meanwhile, most of the rest of the world has yet to industrialize, and evidently feels that industrialization is necessary. China has already become the world’s second-greatest carbon dioxide emitter.

  To reduce carbon dioxide on the necessary scale would mean severe curtailment of the use of fossil fuels, and although this can be made profitable (house insulation could and should become a significant industry), on the whole it is cheaper and easier to continue business as usual. Of course, too, people could be required to insulate their houses by law; but the governments both of the United States and of Britain seem reluctant to pass environmental laws, largely because they are not seen as vote winners. Modern Western-style governments never stop interfering in people’s lives, but they are reluctant actually to govern. The carbon dioxide o
utput of the United States is virtually unabated, and although we have yet to see which way China will go at present, it seems hell-bent on further industrialization. As the dimming soot is removed and carbon dioxide continues to rise, both the magnitude and the speed of global warming seem liable to exceed even the most extreme predictions of the late twentieth century.

  Trees, as ever, are or should be at the heart of all discussion on climate change. The changes in carbon dioxide, in temperature, and in patterns of rainfall will affect them in many ways—and each parameter interacts with all the others, so between them these three main variables present a bewildering range of possibilities.

  Rising carbon dioxide alone—even if temperature and rainfall stayed the same—should accelerate photosynthesis. This, in theory, must increase the amount of carbon in each tree and reduce the amount in the atmosphere—and if enough trees photosynthesized more quickly, they could in theory reduce atmospheric carbon dioxide enough to lower global temperature. That would produce a negative feedback loop: an excellent outcome. We know that rising carbon dioxide can indeed stimulate photosynthesis. Commercial growers sometimes ply their crops with extra carbon dioxide to boost their growth. In large-scale experiments in forests and plantations, groups of trees that have been semienclosed and then given extra carbon dioxide also grow faster, as they fix more carbon.