Planting a tree should include a species selection process that factors in projected climate change over the lifetime of the tree. Image Credit.
Equilibrium between vegetation and climate refers to the state in which the species and ecosystem type best adapted to a particular area actually occupy that area.
At a geologic time scale, Earth’s climate is always changing and as climate changes, the best adapted species for a given geographical area likewise changes. However, for a variety of reasons, the arrival and establishment of the best adapted vegetation may lag behind the climate change. Biogeographers refer to vegetation/climate disequilibrium in this case.
Note that achieving vegetation/climate equilibrium may take hundreds to thousands of years, so the faster climate is changing, the less likely it is that the vegetation will remain in equilibrium with it.
The Holocene Epoch (from about 11,000 B.P. to present) was characterized by a relatively stable climate, and global vegetation has mostly equilibrated with the climate. But now we have entered the Anthropocene epoch in which anthropogenic greenhouse gas emissions are driving a high rate of climate warming. Consequently, long-lived vegetation is beginning to fall out of equilibrium with the climate over wide swaths of the terrestrial surface (albeit that humans have already massively altered global vegetation).
As the disequilibrium gets greater, forests in particular become more stressed and vulnerable to disturbances such as insect outbreaks and fire.
The incidence of fire is already increasing around the world because of climate change and we can expect that trend to continue. For example, my simulations of vegetation change in the Willamette Basin (Western USA) project a several fold increase in the incidence of forest fire in coming decades as the climate changes.
The carbon cycle consequences of a growing vegetation/climate disequilibrium are significant.
1. More fires mean more direct emissions of CO2 and more woody residues (dead trees), which will eventually decompose and emit CO2. Local photosynthesis (CO2 uptake) is reduced in recently burned areas until the vegetation leaf area recovers.
2. Forests stressed by climate change are increasingly vulnerable to pests and pathogens. As with fire, associated damage to trees reduces growth and may cause mortality, and the residual dead trees gradually decompose and return CO2 to the atmosphere.
3. Climate change is increasing Vapor Pressure Deficits (the drying power of the atmosphere), which tends to reduce stomatal opening and hence reduce photosynthesis and uptake of CO2. Plant species are adapted to a specific range of VPD and can die when VPDs exceed their tolerance. Interestingly, the increasing concentration of CO2 from fossil fuel emissions compensates to some degree for VPD-induced stomatal closure because CO2 diffusion into the stomata increases as the concentration gradient between leaf exterior and interior rises. The net effect of these opposing factors varies geographically depending on many variables.
The global impact of increasing disequilibrium between vegetation and climate on the carbon cycle is concerning because it will likely reduce the current terrestrial carbon “sink”. At the global scale, the net effect of biological carbon sources and sinks on land is a carbon uptake equivalent to about 29% of fossil fuel emissions. Much of that carbon accumulation is in wood and soil. The effects of vegetation/climate disequilibrium may reduce the current rate of land-based sequestration, which would leave more fossil fuel-based CO2 emissions in the atmosphere. The annual increase in atmospheric CO2 concentration has increased in recent decades (Figure 1), mostly because of increasing fossil fuel emissions. In the absence of strong emissions reductions, any draw down of the terrestrial sink will tend to further increase that annual uptick in concentration.
Copernicus, Darwin, and Freud are credited with delivering major blows to humanity’s self-image. They didn’t do it on their own of course, but their ideas were notably illuminating. Here, I revisit their insights and discuss two additional blows of that type rendered in more recent years. Awareness of the human limitations implied by these blows may help save us from our present environmental predicament.
Copernicus (1473 -1543) established that – contrary to Church dogma – Earth rotated on its axis and revolved around the sun. Humans could no longer maintain that we are living at the center of the universe. The scientific discipline of astronomy has gone on to reveal how remarkably tiny this planet really is in the context of an immense universe. Knowing that we live on a small planet points to biophysical limits on our current demands for natural resources.
Darwin (1809 – 1882) elucidated the theory of biological evolution, and the corresponding fact that Homo sapiens originated the same way every other animal species on this planet did – through natural processes. We were no longer a special creation of an omnipotent, benevolent god who dictates our aspirations and values. Ironically, though, humanity is coming to have a kind of dominion over the Earth even without the hand of god.
Freud (1856 – 1939) suggested that unconscious processes within our brains have a substantial influence on our thoughts and emotions. He turned out to be wrong in many respects, but his primary insight had merit. We are not even in full control of our own minds. Contemporary cognitive science aims to understand (1) the function (adaptive significance) of specific mental processes, (2) the representations and algorithms by which those processes are implemented, and (3) the underlying neurobiological mechanisms. Insights along those lines may help modify our destructive impulses.
The two recent blows to our self-image come from a biologist and an atmospheric chemist.
The fifth blow is truly aimed at the whole of humanity. Around 2000, atmospheric chemist Paul Crutzen (1933 – 2021) helped consolidate a wide array of observations by Earth System Scientists concerning the baleful influences of humanity on the biosphere and the global environment. He suggested that we have entered a new geologic epoch – the Anthropocene.
In the scientific Anthropocene narrative, humanity has become the equivalent of a geologic force; we are now capable of significantly altering the global biogeochemical cycles. This shocking realization and consequent shift in worldview have been characterized as the “second Copernican revolution”.
Unfortunately, we are altering the global environment in a way that may ultimately be self-destructive (e.g. by inducing rapid global climate change). Our self-image must therefore include the conclusion that we are an existential threat to ourselves.
Recognition of the Anthropocene epoch places a new responsibility on each of us as individuals, and a new responsibility on our species as a whole, to begin managing ourselves – and to some degree begin managing the Earth system – in support of global sustainability.
Given the gathering storm of global environmental change, our world is in dire need of new ways of thinking. Culture is, in part, the set of beliefs, customs, and knowledge shared by a society; and cultural evolution happens when new ideas or concepts are generated by individuals and spread by way of social learning. If a concept is successfully replicated in the minds of most of the people in a society, it could be said to become part of the culture of that society. Here, I examine the concept of the “Great Transition”, an idea that may help a nascent global society grapple with planetary scale environmental change issues.
The “Great Transition” is a theme employed by authors from a variety of disciplines to characterize how humanity must change in the coming decades.
We can begin with Kenneth Boulding (1910-1993). He was an academic economist who published The Great Transition in 1964. Boulding was an expansive thinker and an early advocate of the spaceship Earth metaphor. Because he was publishing in the middle of the Cold War era, he was concerned about human self-destructive tendencies associated with both the global geopolitical situation and the global environment.
Boulding’s Great Transition called for a gradual augmentation or replacement of “folk knowledge” with scientific knowledge. Both are honed by cultural evolution, i.e. specific beliefs are generated, spread, and retained as part of the cultural heritage within specific social groups. Faith in folk beliefs is based on tradition rather than on an understanding of underlying mechanisms. Folk knowledge sometimes serves mainly to foster group identity (e.g. creation myths that build a shared sense of destiny) but other folk beliefs may have practical significance (e.g. knowledge of medicinal plants).
Various alternative ways of knowing (epistemologies) operate quite differently from folk knowledge. In the scientific epistemology, a consensus model of how the world is structured, and how it functions, is built up over time by way of hypothesis formation and testing. One great virtue of the scientific epistemology is that the consensus model of reality can change based on new observations, ideas, and experiments. Specifically, regarding global environmental change, the scientific community has discovered anthropogenically-driven trends in the global environment and has suggested that they pose a threat to human civilization. As is evident in today’s political battles over climate change, scientific discoveries and science-based mitigation strategies are not always consistent with folk knowledge.
Boulding advocated a more consistent reflexivity in human thinking, i.e. a questioning attitude and an openness to changing beliefs. This thinking strategy was something he wanted all humans to share, even though they might be supporting different ideologies.
Another economist (Mauro Bonaiuti) also wrote a book entitled The Great Transition. For Bonaiuti, a global economic crisis is imminent driven by 1) limits on natural resources such as fossil fuels, and 2) an overshoot in societal complexity.
Bonaiuti focused on a trend in growth of Gross Domestic Product (GDP) for developed countries in recent decades. He found a long-term decline in GDP growth (% per year) across a wide range of developed countries. The driving mechanism was Diminishing Marginal Returns (DMR) on investments associated with reaching the biophysical limits of natural resources (e.g. land available for agricultural expansion). He feared this economic trend portended eventual collapse of capitalism and the ascendancy of autocratic regimes.
Bonaiuti’s Great Transition away from that trajectory was characterized by degrowth − reduction in the importance of market exchange, reduced production and consumption, and transitioning towards forms of property and company ownership that feature local communities, small shareholders, and public institutions.
As an Earth system scientist, I agree with Bonaiuti about the human enterprise on Earth hitting the biophysical limits of the Earth system. Regarding complexity though, I am more sanguine. A transition to global sustainability is likely to require more complexity, especially in the form of a more elaborate set of global governance institutions. The energy costs could be paid by an expanded renewable energy infrastructure (hopefully without the expansion hitting its DMR).
Physicist Paul Raskin developed another version of the “Great Transition”, this one aimed more directly at addressing the problems of biophysical limits. The Tellus Institute, with which he is affiliated, produced a broad program of policy prescriptions designed to foster societal change towards sustainability. One of their prescriptions is a renewable energy revolution (which, not surprisingly is also the subject of a recent book by Lester Brown called The Great Transition). The Tellus Institute published Journey to Earthland in 2016, with Earthland here referring to an emerging “country” that includes all nations on Earth (hence a planetary civilization).
For Raskin, the key factor that could unify humanity is the systemic environmental crises that are rapidly engulfing the world (e.g. climate change). People will be forced to work together to address these crises. He sees the needed change as a bottom-up driven process, i.e. a “global citizens movement” with strong participation of civil society.
Considering this convergence by earlier authors on the theme of transition, I adopted the “Great Transition” label for a phase in what I call A Positive Narrative for the Anthropocene. From an Earth system science perspective on the Earth’s history, I developed this six-phase story of humanity’s relationship to the rest of the Earth system. The Anthropocene Epoch alludes to the recognition by geoscientists, social scientists, and humanities scholars that humanity (by way of the technosphere) has become the equivalent of a geologic force. My Great Transition phase comes between a Great Acceleration phase (1945 – 2020) and an idealized future of global sustainability.
An essential aspect of my Great Transition usage is that a new social entity is born – a collective humanity working together to manage (or at least avoid wrecking) the Earth system as we know it. The coalescence of the United Nations − and its successes such as the Montreal Protocol − hints at the possibilities.
The great inequality in wealth at all scales, the differential responsibility for causing the current global environmental problems, and the differences among people regarding their vulnerability to anthropogenic environmental change, makes it fair enough to question whether there even can be a global “we”. However, a majority of humans (5.2 billion out of 7.7 billion) now have a cell phone. Almost all contemporary humans aspire to use energy and natural resources to achieve and maintain a reasonably high standard of living. That striving is, of course, causing global environmental change. So, indeed, there is a global “we”. And a transition to global sustainability is impossible unless most people on the planet acknowledge membership in that “we”.
The Great Transition must be a global scale phenomenon. However, the actual changes required will be made across a range of scales from individuals (decisions as consumers and voters), to nation-states (e.g. subsidies for renewable energy), to global (e.g. resolutions of the United Nations). Let’s consider several of the important dimensions of the Great Transition.
The Biophysical Dimension
Earth system scientists have identified a set of nine planetary boundaries (e.g. the atmospheric CO2 concentration), and the Great Transition will mean regulating human impacts on the environment enough to stay within those boundaries. At present, the quantitative estimates for those boundaries have significant uncertainties and a robust commitment to continued research is needed. The research will include continued improvement in our capability to monitor and model the Earth system. Model simulations are needed to evaluate the consequences of overshooting the planetary boundaries, as well as possible mitigation strategies (e.g. a carbon tax) that could prevent the overshoot.
The Technological Dimension
The technological dimension of the Great Transition is concerned with discovering and implementing the changes to the technosphere that are needed to achieve global sustainability. As noted, a key requirement will be a new renewable energy infrastructure. Pervasive advances are also needed in transportation technology, life cycle analysis, and in closed loop manufacturing. Technological fixes must be carefully scaled up since unintended impacts may emerge in the process. The field of Science and Technology Studies is beginning to systematically address the relevant issues. I have previously characterized the product of integrating the technosphere and biosphere as the sustainable technobiosphere (Figure 1).
The Psychological Dimension
We all have a personal identity. It begins with the self-awareness that we grow into during childhood; and it evolves over the course of our life. We typically identify ourselves as members of various groups and there is often a psychological tension within a human being between independence and group membership.
These groups may include family, ethic group, professional group, and religious affiliation, as well as citizenship in a city, a state, and a nation. Membership in a group is recognized as conveying rights and responsibilities.
As noted, an essential feature of the Great Transition will be that individuals augment their multiple existing group memberships with membership in new groups focused on addressing human-induced environmental change.
The Education Dimension
One of humanity’s most important evolved traits is the capacity to transfer knowledge by way of social learning. Language is a tool for efficient communication of information horizontally (within a generation) and vertically (across generations). The Great Transition will require a global society with citizens who understand enough Earth system science to appreciate the need for humanity to manage its impact on the biosphere and the rest of the Earth system. They must generally be literate, so as to assimilate basic information about what is going on in the world, and to some degree be scientifically literate so they can understand the underlying mechanisms that explain what is going on.
The Geopolitical Dimension
Since the Treaty of Westphalia in 1648, what happens within national borders is in principle largely left to the inhabitants of the nation. Nations have subsequently become protective of their national sovereignty.
Issues of global environmental change now disrupt and challenge that principle. National emissions of greenhouse gases sum up to a major global scale impact on the environment. National sovereignty is thus not sacrosanct; nations must cooperate, or they will all suffer. The current global wave of nationalism, especially the push back against commitments to international negotiations and agreements, is inhibiting movement towards a Great Transition. A significant step forward would be formation of a new global environmental governance institution, such as the proposed World Environment Organization.
The Great Transition concept has thus far spread rather thinly across humanity. But as a global society forms in response to global environmental change, it should become foundational.
Humans are story-telling animals. Our brains are wired to assimilate information in terms of temporal sequences of significant events. We are likewise cultural animals. Within a society, we share images, words, rituals, and stories. Indigenous societies often have myths about their origin and history. Religious mythologies remain prevalent in contemporary societies.
The discipline of Earth System Science has revealed the necessity for a global society that can address emerging planetary scale environmental change issues – notably climate change. A shared narrative about the relationship of humanity to the biosphere, and more broadly to the Earth system, is highly desirable in that context.
The most prevalent narrative about humanity’s relationship to the Earth system emphasizes the growing magnitude of our deleterious impacts on the global environment (think ozone hole, climate change, biodiversity loss). The future of humanity is then portrayed as more of the same, unless radical changes are made in fossil fuel emissions and natural resource management.
In the process of writing a book for use in Global Environmental Change courses, Ideveloped an elaborated narrative for humanity − still based on an Earth system science perspective but somewhat more upbeat. I used the designation Anthropocene Narrative to describe it because Earth system scientists have begun to broadly adopt the term Anthropocene to evoke humanity’s collective impact on the environment.
There are of course many possible narratives evoked by the Anthropocene concept (e.g. the historical role of capitalism in degrading the environment), all worthy of study. But for the purposes of integrating the wide range of material covered in global environmental change classes, I identified a six stage sequence in the relationship of humanity to the rest of the Earth system that serves to link geologic history with human history, and with a speculative vision of humanity’s future (Figure 1). The stages are essentially chapters in the story of humanity’s origin, current challenges, and future. The tone is more hopeful than dystopianbecause our emerging global society needs a positive model of the future.
The chapters in this Anthropocene narrative are as follows.
Chapter 1. The Pre-human Biosphere
The biosphere (i.e. the sum of all living organisms) self-organized relatively quickly after the coalescence of Earth as a planet. It is fueled mostly by solar energy. The biosphere drives the global biogeochemical cycles of carbon, nitrogen, and other elements essential to life, and plays a significant role in regulating Earth’s climate, as well as the chemistry of the atmosphere and oceans. The biosphere augments a key geochemical feedback in the Earth system (the rock weathering thermostat) that has helped keep the planet’s climate in the habitable range for 4 billion years. By way of collisions with comets or asteroids, or because of its own internal dynamics, the Earth system occasionally reverts to conditions that are harsh for many life forms (i.e. mass extinction events). Nevertheless, the biosphere has always recovered − by way of biological evolution − and a mammalian primate species recently evolved that is qualitatively different from any previous species.
Chapter 2. The Primal Separation
Nervous systems in animals have obvious adaptive significance in term of sensing the environment and coordinating behavior. The brain of a human being appears to be a rather hypertrophied organ of the nervous system that has evolved in support of a capacity for language and self-awareness. These capabilities are quite distinctive among animal species, and they set the stage for human conquest of the planet. The most recent ice age receded about 12,000 year ago and a favorable Holocene climate supported the discovery and expansion of agriculture. With agriculture, and gradual elaboration of toolmaking, humanity ceased waiting for Nature to provide it sustenance. Rather, Nature became an object to be managed. This change is captured in the Christian myth of Adam and Eve’s expulsion from the Garden of Eden (Figure 3). They lived like all other animals in the biosphere until they became self-aware and began to consciously organize their environment.
Chapter 3. The Build-out of the Technosphere
The next phase in this narrative is characterized by the gradual evolution and spread of technology. An important driving force was likely cultural group selection, especially with respect to weapons technology and hierarchical social structure. The ascent of the scientific worldview and the global establishment of the market system were key features. Human population rose to the range of billions, and the technosphere began to cloak Earth (Figure 4). The Industrial Revolution vastly increased the rate of energy flow and materials cycling by the human enterprise. Telecommunications and transportation infrastructures expanded, and humanity began to get a sense of itself as a global entity. Evidence that humans could locally overexploit natural resources (e.g. the runs of anadromous salmon in the Pacific Northwest U.S.) began to accumulate.
Chapter 4. The Great Acceleration
Between World War II and the present, the global population grew from 2.5 billion to 7.8 billion people. Scientific advances in the medical field reduced human mortality rates and technical advances in agriculture, forestry, and fish harvesting largely kept pace with the growing need for food and fiber. The extent and density of the technosphere increased rapidly. At the same time, we began to see evidence of technosphere impacts on the environment at the global scale – notably changes in atmospheric chemistry (Figure 5) and losses in global biodiversity.
Chapter 5. The Great Transition
This phase is just beginning. Its dominant signal will be the bending of the exponentially rising curves for the Earth system and socio-economic indicators that define the Great Acceleration (Figure 5 above). Global population will peak and decline, along with the atmospheric CO2 concentration. Surviving the aftermath of the Great Acceleration with be challenging, but the Great Transition is envisioned to occur within the framework of a high technology infrastructure (Figure 6) and a healthy global economy. To successfully accomplish this multigenerational task, humanity must begin to function as a global scale collective, capable of self-regulating. Neither hyper-individualism nor populist tribal truth will get us there. It will take psychologically mature global citizens, visionary political leaders, and new institutions for global governance.
Chapter 6. Equilibration
Human-induced global environmental change will continue for the foreseeable future. The assumption for an Equilibration phase is that humanity will gain sufficient understanding of the Earth system – including the climate subsystem and the global biogeochemical cycles – and develop sufficiently advanced technology to begin using the technosphere and managing the biosphere to purposefully shape the biophysical environment from the scale of ecosystems and landscapes (Figure 7) to the scale of the entire planet. Humanity is a part of the Earth system, meaning it must gain sufficient understanding of the social sciences to produce successive generations of global citizens who value environmental quality and will cooperate to manage and maintain it. The challenges to education will be profound.
As noted, this Anthropocene Narrative is largely from the perspective of Earth system science. In the interests of coherence, humanity is viewed in aggregate form. Humanities scholars reasonably argue that in the interests of understanding climate justice, “humanity” must be disaggregated (e.g. by geographic region or socioeconomic class). This perspective helps highlight the disproportionate responsibility of the developed world for driving up concentrations of the greenhouse gases. The aggregated and disaggregated perspectives on humanity are complementary; both are needed to understand and address global environmental change issues.
The Anthropocene Narrative developed here is broadly consistent with scientific observations and theories, which gives it a chance for wide acceptance. The forward-looking part is admittedly aspirational; other more dire pathways are possible if not probable. However, this narrative provides a solid rationale for building a global community of all human beings. We are all faced with the challenge of living together on a crowded and rapidly changing planet. The unambiguous arrival of global pandemics and climate change serve as compelling reminders of that fact. A narrative of hope helps frame the process of waking up to the perils and possibilities of our times.
Recommended Video: Welcome to the Anthropocene (~ 3 minutes)