8 The Biosphere: Cycles of Life
In nature nothing takes place in isolation. Everything affects and is affected by every other thing, and it is mostly because this manifold motion and interaction is forgotten that our natural scientists are prevented from gaining a clear insight into the simplest things.
—FREDERICK ENGELS1
ALL LIVING CREATURES INTERACT with other species and their surroundings. The degree of stability and the amount of biomass productivity of an ecosystem are related to the complexity of these relationships.
Ecosystems are composed of assemblages of living organisms, including those living within and on the surfaces of other organisms, all interacting among themselves as well as with their habitat—the water, the air, soil, and climate. Large geographic areas containing communities of plants and animals adapted to a particular environment (especially climate and soils) are referred to as biomes. These overlap in transition zones known as ecotones, which frequently exhibit greater biodiversity than each individual biome of which they are composed.
Many think of particular ecosystems or biomes as isolated islands. However, biomes interact, for example, with birds and insects seasonally migrating from one biome to another. Disparate biomes, in location and type, may impact one another over distances of thousands of miles, as is the case with the Amazon, which is fertilized with dust from storms originating in the Sahara and with weather systems that begin off the coast of West Africa and emerge as hurricanes in the Caribbean.2 Another important interaction between biomes occurs when sediment-laden rivers flow out of mountain forests, depositing their loads in valley floodplains. Thus the biosphere as a whole and the various biomes are open systems with exchanges of organisms, minerals, water, and gases constantly occurring.
If we focus only on individual species our knowledge remains incomplete. Doing so overlooks emergent properties of ecosystems—those attributes unexpectedly arising out of species interactions and holding many lessons for humanity. Though acknowledging inter-connectedness, we still need to separate out and focus on various phenomena to gain a better understanding of how the planet operates.
A better understanding of the multitude of effects and mechanisms that organisms use to help them thrive under particular conditions, including working in conjunction with other organisms, can help us design more sustainable ways to meet our needs.
COOPERATION AND LIFE
The world is in a constant state of change. When an organism goes about its normal life activities it changes its surroundings as well as itself. As soil minerals dissolve in water, both the minerals and the water are changed in the process. As the Greek philosopher Heraclitus wrote some 2,500 years ago: “No man ever steps in the same river twice, for it’s not the same river and he’s not the same man.” The water molecules that passed by the first time are long gone by the time one steps in again. Likewise, one can never walk into the same forest twice. Walking in the forest creates measurable biological and chemical changes: the soil under your footsteps is different from before you took that step. The passage of time also causes chemical and physical changes in each person, including changes in mental states; the memory of a prior walk alters how we perceive a future one.
One of the central concepts of Darwinian evolution is variation through natural selection, a process commonly reduced to the phrase “survival of the fittest.” This is typically misunderstood as the single defining feature of evolutionary theory. This concept is widely promulgated in our society because it fits so well with the ideology and practice of competition in capitalism. People and institutions are encouraged and compelled to compete and rewarded for their success. Whichever businessperson thrives while others flounder is by definition the fittest capitalist.
Though much less studied, cooperation within and among species is just as critical as competition to the process of evolution. Cooperation, which was critical for survival of the hunter-gatherer societies that prevailed for most of our existence, is one of the keys to the evolution and success of our species as well as many others.
“Nature nurtures life through communities,” says Fritjof Capra, physicist, author, and cofounder of the Center for Ecoliteracy. “This is a process that started with the first single-celled organisms. Life … took over the planet by networking, not combat.”3 Cooperation, which takes many forms between and within species, is common throughout the history and scope of the four-billion-year-old story of life on this planet.
Cooperation exists everywhere; for example, a number of species of microorganisms tend to live “in complex communities, where they communicate with one another to cooperate for the greater good.”4 When a critical population of many bacteria is reached they exude sticky material that makes a protective mat or biofilm that they live within. Inside multicellular organisms, the various types of cells are not in competition under normal healthy conditions but rather receive assistance from other types of cells—as when red blood cells deliver oxygen from the lungs throughout our bodies.
In plants, nitrogen-fixing bacteria create a home inside the roots of legumes, obtaining sugars from the plant in order to live and providing nitrogen to the plant in a form it can use. Large populations of microbes living near plant roots, an area called the rhizosphere, receive sugars and other compounds exuded from roots and provide the plant with soluble forms of phosphorus and a variety of organic substances that stimulate plant growth.
Similarly, there is intimate cooperation between certain fungi (mycorrhizae) and plant roots in which plants supply fungi with energy-rich compounds while the fungi help the plant obtain water and nutrients in the soil. The fungi even help plants exchange organic compounds. One study in a forest indicated that some 40 percent of the carbon in fine roots originated from the photosynthesis of neighboring trees.5 Trees also signal one another using the underground network of connecting mycorrhizae to warn of insect attacks. Nature is full of such examples: bees pollinating flowers as they obtain pollen, fish known as “cleaner fish” eating parasites from the mouths of other fish, cattle egrets and cowbirds eating flies and bugs from the backs of cattle. Clearly, cooperation is one of the most important ways that species and individuals within species interact.
Certain structures common to eukaryotes (all cellular life with DNA enclosed in a nucleus) such as the chloroplasts in green plants, the energy-converting mitochondria found in all plant and animal cells, began as free-living organisms that became incorporated into the normal workings of larger cells. In these instances cooperation led to some organisms being integrated into cells of another, resulting in the creation of new organisms. According to Martin Nowak, director of the Program for Evolutionary Dynamics at Harvard University and an internationally recognized scholar on evolution and game theory:
Co-operation was the principal architect of 4 billion years of evolution. Co-operation built the first bacterial cells, then higher cells, then complex multicellular life…. Co-operation can draw living matter upward to higher levels of organisation. It generates the possibility for greater diversity by new specialisations, new niches and new divisions of labour. Co-operation makes evolution constructive and open ended.6
In order to grow, exist, and reproduce, all living organisms need sources of essential materials and sinks that can absorb their wastes—which are in turn frequently used as sources of energy and nutrients by other organisms. As organisms go about their lives, the biochemical processes are commonly grouped together under the term metabolism. This includes production or synthesis of materials—such as proteins, carbohydrates, and fats for growing new tissue and storing energy—as well as the breakdown of substances to produce energy and to provide chemical building blocks to make other molecules, repair damaged tissue, and reproduce. The chemical and biological surroundings of organisms and the organisms themselves are changed by resources they use and by the release of waste products.
As discussed in chapter 3, Karl Marx used the word metabolism in an enlarged sense to describe the interactions between humans, our social system, and our physical, biological, and chemical surroundings.
The interaction of living organisms with the non-living as well as the living part of the world was highlighted by Engels: “Animals … change the environment by their activities in the same way, even if not to the same extent, as man does, and these changes, as we have seen, in turn react upon and change those who made them.”7 The same can also be said of plants, as they remove nutrients and water from soils, depleting these substances, even if only temporarily, making it more difficult to obtain their basic needs in the future if the nutrients and water are not replenished. There is a continuous exchange of matter and energy among organisms and between organisms and the biosphere.
In many interactions, species cooperate to make life possible. However, there are other types of cooperation, such as signaling interactions; for example, most plants give off gaseous substances when attacked by insects, thereby stimulating their neighbors to start making defense chemicals to help withstand a similar assault.
TO SHAPE AND BE SHAPED
Striking examples of a species interacting with the rest of the environment took place long before multicellular life evolved, illustrating the extraordinary environmental changes caused by living organisms. In a very real sense, the physical earth and the biological inhabitants created each other and evolved together. Oxygen is far too reactive a gas to have existed in the early atmosphere of our planet. Any small amount of oxygen that might have been produced would have been rendered insoluble and unreactive by combining with other elements such as iron. Because there was none in the early atmosphere, something must have put oxygen there and brought it up to a relatively high level.
It was a single-celled bacterial species that brought about this singularly significant change. Cyanobacteria emit oxygen as a byproduct of photosynthesis, as do the terrestrial plants that developed much later in evolutionary history.
Cyanobacteria, often referred to as blue-green algae, are capable of photosynthesis and nitrogen fixation, providing the organism with energy, the complex carbon-based molecules it needs, and nitrogen in forms that can be used to make amino acids and proteins. “Cyanobacteria are arguably the most successful group of microorganisms on Earth. They are the most genetically diverse; they occupy a broad range of habitats across all latitudes, widespread in freshwater, marine and terrestrial ecosystems, and they are found in the most extreme niches such as hot springs, salt works, and hypersaline bays.”8 While not the only nitrogen-fixing organism present, a filamentous form of cyanobacteria, Anabaena azollae, is important for maintaining nitrogen fertility in rice paddies that have been farmed for centuries.
The production of oxygen by oceans full of cyanobacteria 2 billion years ago created the oxygenated atmosphere that earth has had ever since. (It is thought that the current level of atmospheric oxygen—around 21 percent—was reached only 400 million years ago, after land plants colonized the earth.) As a consequence of the production of so much oxygen, organisms that evolved earlier and were then living in direct contact with the atmosphere had no way of coping with high concentrations of oxygen and were decimated.
This large die-off simultaneously created the opportunity for the evolutionary development of organisms that require oxygen, including multicellular forms of life. Today, anaerobic organisms require an oxygen-free environment such as in lake or ocean sediments or inside our digestive tracts.
“In nature nothing takes place in isolation,” Engels’s important insight, is now a core principle of ecology. Studying cells or individual organisms separate from this reality can produce important understandings and knowledge. However, that reductionist approach is a major obstruction to advancing an understanding of our world in all its complexity. The real ecological action takes place as organisms interact with other organisms and their surroundings. As they do so, properties emerge that the individual organisms don’t have by themselves. For example, while nitrogen-fixing rhizobia bacteria and legume plants can live without each other and can be studied separately, it is only when they are living together that nitrogen fixation occurs as a result of their interactions. One would never know that bees or locusts form swarms under certain circumstances from studying individuals rather than the behavior of populations. The near absence of holistic thinking in Western science—considering the whole system and examining the interactions occurring within it—continues to be responsible for the slow progress in many branches of science. Although lip service is given to the importance of holistic thinking, in most fields, and with few exceptions, researchers study isolated phenomena, disregarding the interactions among organisms and between organisms and their chemical and physical surroundings.
In recent earth history, the activities of animals and plants, along with geophysical and chemical weathering processes, have helped to maintain relatively stable atmospheric, oceanic, and soil oxygen and carbon dioxide concentrations. That is until human activities of the last century occurred, especially during the Great Acceleration.
FOOD WEBS
Green plants are the source of energy for almost all other organisms.9 These primary producers use the energy of sunlight to drive photosynthesis, a process in which they incorporate carbon dioxide from the atmosphere to produce energy-rich molecules that are then used to carry out essential metabolic processes.
Virtually all organisms unable to photosynthesize use solar energy that is first captured by plants. The most simplified general pattern is a connection of organisms arranged in a network, or web, dependent on one another for survival. It is, of course, much more complicated and extensive than this. Nutrients and energy are transferred from one organism to another, with some of the energy dissipated as organisms use it for their growth, development, and reproduction.
The interactions result in food webs, in which the waste matter of one organism, or the organism itself, becomes the food source for another in the web of life. For example, many soil fungi feed on the remains of plants (primary producers), later becoming a nutrition source for nematodes that can then be eaten by an arthropod such as a beetle (see Figure. 8.1). There is a continuous flow of energy and wastes between organisms and other parts of the environment.
The energy from the sun that is incorporated into plants is transferred to organisms in the second tropic level (the first consumers), then to the third tropic level (that feed off the first consumers), and so on. It is common to refer to organisms higher up on the food web as being at a higher tropic level. However, relationships among organisms are not hierarchical. There are organisms that feed on others, such as when a bacteria-feeding nematode uses bacteria as a food source. But when an organism that appears to be higher up the food web dies, it becomes food for those lower down, completing a cycle of nutrients.
Earlier we discussed how the workings of capitalist economies created disturbances and rifts in the natural cycles of water, nutrients and gases (see chapter 3). To grasp how we might consciously interact with the biosphere as we provide ourselves with life’s needs, including healthy ecosystems, we must understand the intricate balance of nature and how natural processes and cycles functioned before such large disturbances occurred.
ORGANISMS PARTICIPATE IN GLOBAL CYCLES
The exchange of substances between an organism and its surroundings changes the chemical, biological, and physical conditions in its vicinity. Through their interactions with their local environments, organisms shape and reshape the environments in which they are living. Though cyanobacteria may be the species that had the largest effect at the planetary level until humans came along, other organisms are involved in important natural processes and cycles.
An estimated 60 percent of the precipitation that falls on relatively undisturbed land enters the soil and is stored there in a form that’s mostly available to plants. The remaining 40 percent flows either through the soil into aquifers and springs or flows overland into streams, rivers, lakes, and wetlands. Plants need a lot of water to grow. To produce one pound of the edible portion of food plants take hundreds or even a thousand or more pounds of water.10 About 90 percent of this water is taken up from the soil and then transported through the plant’s specialized tubes to the leaves, where it evaporates from the same openings that provide entry for the CO2 needed for photosynthesis. Thus most of the water stored in soil and taken up by plants is returned to the atmosphere—an essential part of the hydrologic cycle.11
The structural condition of soils—how porous they are and the number of large pores open at the surface—is critical for controlling how much water infiltrates into soil versus the quantity of surface runoff. When undisturbed by humans, soil structure is primarily a function of the living organisms in it: plants, fungi, bacteria, earthworms, beetles, and so on. In fact, soil would not even be soil without living organisms and their remains; it would simply be ground-up sterile rocks and minerals. The higher the rate of biological activity and the better the physical condition, the more that soils can accept rainfall and store it in their pores. This means that less precipitation runs off the land, which means less soil erosion, better recharge of aquifers, more even flow of rivers and streams, and more water available for plants to use. When plants are present, rain first hits the leaves, lessening the impact of the raindrops on the soil surface.
Another aspect of the interaction of living organisms and the water cycle has become appreciated only in the last decade or so.12 There are transfers into the atmosphere of organisms, dust particles, and gaseous organic compounds given off by plants. As wind sweeps over the land and sea and waves break in the ocean, organisms, organic compounds, and particles are picked up and whisked along, eventually reaching high into the atmosphere. Almost all rainfall begins its descent into the atmosphere as ice. The compounds, organisms, and inorganic particles become the nuclei around which ice particles form. One of the researchers on the phenomena of bacteria and ice nucleation in clouds, David Sands, has commented: “We need to recognize these microbes as a part—maybe even a major part—of meteorological processes.”13 In another example of organisms influencing precipitation, the high evaporation rates of tropical rain forests create low atmospheric pressure relative to surrounding regions. These forests “draw in moist air that converges and rises, generating annual rainfall that surpasses (typically at least double) local evaporation.”14
The Carbon Cycle
Take a breath and then slowly let it out. During this process, repeated unconsciously thousands of times each day, you are interacting with the global atmosphere. With each inhalation and exhalation you are depleting the atmosphere ever so slightly of oxygen and enriching it ever so slightly with carbon dioxide. As the cells in our bodies work, they take in oxygen to function and emit carbon dioxide as a waste product. The exchange of gases that occurs during breathing, resulting from the process of aerobic respiration is a metabolic interaction between a human and the atmosphere.
Soils breathe as if they were single organisms. Soil-dwelling microorganisms, medium-size animals such as nematodes and rotifers, and larger organisms such as ants, earthworms, and plant roots go about everyday life processes and in doing so modify the composition of the soil. Carbon dioxide given off by these organisms enters soil pore spaces and diffuses up to the atmosphere. Simultaneously, soil organisms take up oxygen, lowering its concentration in the soil’s air-filled pores, causing it to diffuse from the atmosphere into the ground. Wind and changes in atmospheric pressure assist the continual movement of oxygen and carbon dioxide into and out of soils.
The atmospheric carbon dioxide curve (see Figure 3.3, page 87), which shows steadily rising CO2 levels since the 1950s, indicates small fluctuations during the year. In the Northern Hemisphere, where the Mauna Loa Observatory is located, when plants are less active but other organisms are using oxygen and giving off carbon dioxide, atmospheric carbon dioxide content increases slightly, reaching a peak in early spring. But the use of huge amounts of carbon dioxide in the process of photosynthesis when plants are actively growing (late spring through summer) is larger than the release of carbon dioxide by respiring organisms, leading to a small decrease of atmospheric CO2.
Figure 8.2: Terrestrial Carbon Cycle
Note: Boldface indicates carbon losses from soil.
Source: Fred Magdoff.
A large part of the global carbon cycle occurs as plants remove CO2 from the atmosphere during photosynthesis and the respiration of countless organisms, feeding directly or indirectly on plants, returns carbon dioxide fixed by plants to the atmosphere. But the uptake and release of CO2 is not the only gaseous biological interaction involving carbon. For example, microorganisms in wetland soils produce methane (natural gas, or CH4—a greenhouse gas that, pound for pound, has more than twenty times the warming effect of CO2), with a portion reaching the atmosphere.
Nutrient Cycles
“For soil thou art, and unto soil thou shalt return.” These words from Genesis 3:19 are literally true for most terrestrial organisms.15 Out of the eighteen nutrients essential for plants to grow, all except carbon and a portion of oxygen are taken up from the soil. When animals eat plants, or eat other animals that have eaten plants, they ingest these nutrients. For example, the calcium and phosphorus dissolved in soil water is taken up by plant roots and moved together with water through specialized tubes to leaves, fruits, and seeds. Animals eat the plants, ingesting the calcium and phosphorus that is then used to build bones and manage other metabolic processes in our bodies.
When trees or grasses die, their roots, stems, and leaves decompose and nutrients are released back into the soil. Animals also facilitate a cycling of nutrients when they release waste products in the form of urine and feces not too far from where food is consumed (Figure 8.2, page 224). But a true nutrient cycle, in which nutrients return to the original point from which plants removed them, is only one type of flow. Nutrients removed from a plot of land in the form of food for use in some other location is another type of flow. Nutrient flows also occur on a global scale, as when the dust from the Sahara Desert and the Sahel region of North Africa is picked up and transported to the southeastern United States and South America. One of the ways that the Amazon forest has been able to maintain its fertility over centuries is through the large input of nutrients from the Sahel: an estimated 27 million tons of dust is transported from Africa annually, contributing some 22,000 tons of phosphorus to the Amazon basin, enough to balance losses from runoff and leaching.16 This flow of nutrients interacts with the water cycle: years of higher than normal rainfall in the Sahel promote plant growth, and are followed by years of below-normal dust transfers to the Amazon as plants help to keep soil in place.
In chapter 3 we described a rift in the long-distance cycling of nutrients by many species of animals as a result of ruthless exploitation for profit. In earlier eras seabirds, large land and sea animals such as bison, elephants, and whales, and ocean fish that spawn in fresh water (anadromous) played vital roles in moving nutrients far away from high concentrations and distributing them around the planet, enhancing Earth’s fertility and biological productivity.17 Whales move nutrients from deep in the ocean to surface waters, anadromous fish and seabirds move them from the ocean to the land, and migrating herds of herbivores distribute nutrients over long terrestrial distances.
The global nitrogen cycle is also of critical importance. Nitrogen is an essential nutrient for plants and animals, mainly because it is a component of proteins, but plants and animals are not able to utilize the main form in which it exists in the atmosphere, as nitrogen gas (N2), representing 78 percent of the atmosphere. Plants obtain nitrogen in a number of ways; the primary sources derive from microorganism—living either free in the soil or within plant roots (in legumes, for example). These organisms are able to convert nitrogen gas into a form that plants can use. (The industrial process used to make nitrogen fertilizer requires very high temperatures and pressures and lots of energy (fossil fuels).) Microorganisms also produce N2 and N2O—nitrous oxide, also a greenhouse gas and hundreds of times more potent than CO2—when plentiful levels of nitrate are present and soils are wet. This depletes the soil of nitrogen in forms that plants utilize.
PLANTS INTERACT WITH OTHER ORGANISMS
Plants are in a dynamic interrelationship with various organisms and the chemical and physical environment in soil and atmosphere (Figure 8.3). In addition to participating in global cycles, plants sense their environment and respond to ensure better nutrition, growth, and protection against diseases and insects. Plants have such sweeping effects that “soil undergoes great and lasting evolutionary changes as a direct consequence of the activity of the plants growing in it, and these changes in turn feed back on the organisms’ conditions of existence.”18
Figure 8.3: Plant Interactions with Soil and Atmosphere
Source: Modified from Fred Magdoff, “Creating an Ecological Civilization,” Monthly Review 62(8):1–25 (January 2011).
As with the forest trees mentioned earlier, most plants grown for food form mutually beneficial associations with mycorrhizae fungi.19 The fungus, a different type of mycorrhizae than found with trees, grows partially inside the plant root. It also sends out root-like hyphae into the nearby soil, essentially enlarging the plant’s root system. The fungus receives sugars produced by photosynthesis and provides the plant with many benefits: by exploring more of the soil than roots can do alone it has access to greater quantities of nitrogen, phosphorus, and water. The fungus also helps to make phosphorus in the soil more soluble and available for uptake. If those advantages aren’t enough, the presence of mycorrhizae lessens the ability of disease organisms to attack roots.
Plants continually produce defense compounds such as nicotine and tannic acid that offer protection from attack by bacteria, fungi, and viruses and ramp up production in response to infection. Some of the chemicals in fruits and vegetables that help to ward off diseases and insects induce mild stress in humans, which is believed to account for their health benefits, possibly including protection against brain disorders such as Parkinson’s and Alzheimer’s.20
Bees, other insects, and bats pollinate many plants, and a variety of mammals and birds eat the fruit of plants and disperse their seeds. Approximately 95 percent of Brazilian rain forest trees depend upon animals to spread seeds. Aquatic ecosystems are similarly intertwined and interactive; phytoplankton in the oceans absorb as much carbon dioxide as terrestrial plants, provide sustenance for other marine organisms, and sequester a portion of carbon in the deep ocean sediments when they die.
ANIMAL AND MICROBE INTERACTIONS
When we discuss microbes, the first examples that might come to mind are probably harmful disease-causing organisms. Though there are numerous microbial diseases, there is a whole other dimension to animal–microbe interactions. As Ed Yong, staff science writer at The Atlantic, points out, most microbes do not make us sick: “At worst, they are passengers or hitchhikers. At best, they are invaluable parts of our bodies: not takers of life but its guardians. They help to digest our food, educate our immune systems, protect us from disease, sculpt our organs, guide our behaviour, and maintain our health.”21
Scientists have begun to appreciate the importance of these organisms, their large range in types, and the effects they have on people.22 It is estimated that over 10,000 species of microorganisms are living in cooperative association with healthy humans, with total populations in the trillions of organisms per person. They are inside our mouths and digestive systems and on our skin. This human microbiome allows us to digest food and protects us as we provide these organisms a safe environment and sustenance. It is estimated that these organisms comprise about half the cells in our bodies.23
Human microbiomes co-evolved with our species and contribute to the normal functioning of the body:
A burgeoning body of research suggests that the makeup of this complex microbial ecosystem is closely linked with our immune function. Some researchers now suspect that, aside from protecting us from infection, one of the immune system’s jobs is to cultivate, or “farm,” the friendly microbes that we rely on to keep us healthy. This “farming” goes both ways, though. Our resident microbes seem to control aspects of our immune function in a way that suggests they are farming us, too.24
The diversity of the human microbiome is diminished in rich countries through the overuse of antibiotics, sanitized living quarters, and the routine use of antimicrobial soaps.25 Children often cannot or aren’t allowed to play outdoors in contact with grass and soil. These living conditions, with reduced microbial exposure, can have detrimental health effects. The increase of certain ailments in developed countries may be caused by the imbalance and reduced diversity of gut bacteria.26 There is much more to be learned in this area, and studying organism interactions may provide breakthroughs in human health and ecological understanding.
INTENTIONAL HUMAN INTERACTION WITH THE BIOSPHERE
Humans have developed a way of living and interacting with the environment that involves, in the terminology of Canadian ecologist C. S. Holling, three unique aspects: foresight and intentionality, communication, and technology.27 Human activities are generally intentional and can be thought through ahead of time, allowing the consideration of outcomes of individual actions. When results are not ecologically or socially satisfactory, alternative strategies and techniques can be used to modify activities (assuming they don’t conflict with the interests of those in charge of the economy). Or as Frederick Engels wrote, “We have the advantage over all other creatures of being able to learn [nature’s] laws and apply them correctly.”28
Although communication is a general characteristic of all organisms, from bacteria to land plants to animals, humans have a unique ability to communicate ideas and experiences and our technology can spread information around the globe in milliseconds. Other technologies that humans have developed—from the use of fire to control of vegetation, to gigantic mining equipment, to electric generating plants spewing pollutants—have given us the ability to greatly influence large areas of Earth, well beyond the local or temporary effects that most organisms exert. However, as biologist Stephen Mulkey has written:
Presently human-caused climate change is an amplifier, rather than a primary driver, of human impacts on ecosystems. Toward the middle of this century, climate change will inexorably become the dominant cause of ecological restructuring of the biosphere, causing species displacements and local, regional, and global extinctions…. The double whammy of human overexploitation and accelerating climate change, if unchecked, will result in progressive ecological disruption on a scale not seen on Earth since the K-T Extinction 66 million years ago when catastrophic geologic events were the agents of wholesale disruptions of all of our planet’s systems. There is no other analog in the recent geological record that compares to the speed and comprehensive nature of the transformation unfolding during this century and beyond.29
While nature tends to operate in a circular fashion, capitalist economies operate linearly—extracted resources are refined and manufactured into products that are shipped and used elsewhere and eventually discarded, with waste produced at each step of the process. Although the idea of a circular economy has begun to generate a lot of interest because of the depredations of capitalism, we will need a different social-economic system to actually operate a more circular economy—one in which the decision-making processes incorporate the wisdom of all people working together to maintain ecological health and integrity.30
In the following chapter we discuss important aspects of resilient systems, what they are like socially and ecologically, and ways to think about creating them. This means learning from nature and four billion years of evolutionary experiments.
