The technosphere is gearing up for a full mobilization against rising greenhouse gas concentrations and associated climate change. The struggle to bring down methane emissions is a key feature of that effort; thus, initiatives by individuals, NGOs, industry, and governments deserve our attention and support. The dangerous trajectory of the atmospheric methane concentration (Figure 1) speaks to the urgency of acting now.
The increasing concentration of methane (CH4) in the atmosphere contributes about 23% to anthropogenic strengthening of the greenhouse effect on Earth. As with carbon dioxide (CO2), the rising concentration of methane in the atmosphere must peak as soon as possible if humanity is to avoid a global environmental change crisis. A significant difference between these two greenhouse gases is that methane has a relatively short atmospheric lifetime (~ 8 years) and hence its concentration will respond rapidly to reductions in emissions.
Scenarios for limiting Earth’s warming to 2oC or less assume that methane emissions will peak soon, followed by a peak and fall off in the methane concentration. However, rather than shrinking, emissions are actually increasing and the rate of annual increase in the methane concentration is growing (Figure 2).
The concentration of methane in the atmosphere is the net effect (Figure 3) of sources (emissions) and sinks (consumption). Human driven sources amount to about 60% of total sources. The primary sink of methane is the hydroxyl radical (OH), which is produced in the atmosphere photochemically. The OH molecule has a very short lifetime (~ 1 second) and is difficult to measure. From modeling of atmospheric chemistry and limited OH observations, the oxidation capacity of the atmosphere is considered stable, but there is concern that the increasing methane emissions are extending the atmospheric lifetime of methane and therefore increasing its global warming potential per molecule emitted.
The tripling of methane concentration since around 1800 (Figure 4) is largely attributable to human factors, including expansion of rice agriculture, increase in the number of ruminant livestock, build out of the fossil fuel infrastructure, a rising number of landfills and municipal waste facilities, and more biomass burning associated with agriculture and deforestation.
Another major factor is the number of ruminant livestock on the planet, which continues to increase in association with growth in the human population and its level of affluence. Deforestation and related biomass burning are also on the rise (2010s > 2000s), notably in Brazil.
Although recent increases in methane emissions are related directly to human factors, Earth system scientists are also concerned about possible increases in emissions from natural methane sources. These include 1) high latitude wetlands and shallow seas where warming temperatures increase rates of decomposition and melting of frozen methane hydrates, and 2) extensive tropical latitude wetlands, where warming temperatures similarly increase rates of decomposition. The potential for pumped up high and low latitude natural sources in response to climate warming is worrisome because it would indicate that a positive (amplifying) feedback to global warming had been engaged. There will be little that humanity can do to disengage that feedback once it gets started.
A lot could be done to reduce current methane emissions of anthropogenic origin, what I refer to as a teleological feedback to climate change.
1) Much of the leakage from the fossil fuel infrastructure could be eliminated if the industry took greater precautions (probably requiring stronger regulations). The Biden clean energy plan includes provisions for reducing methane emissions from the oil and gas sectors of the economy in the United States. An especially exciting development is that the Environmental Defense Fund is working to build an operational satellite-based methane monitoring system, which will report areas of leakage in near real time.
The prospects for a rapid peak in global methane emissions, followed by a peak in concentration, are linked to success in bringing down CO2 emissions. The potential problem is that if CO2 driven climate change continues in a business-as-usual fashion, it is possible that natural wetland emissions will increase, which would tend to cancel out successes in reducing anthropogenic methane emissions.
Despite quite a bit of uncertainty about past and future trends in the methane budget, Earth system scientists agree that human-driven methane emissions can and should be reduced.
The developmental task of building a personal identity is becoming ever more complicated. While some aspects of identity come with birth, others are adopted over the course of maturation. Increasingly, each person has multiple identities that are managed in a complex psychological juggling act.
Citizenship − generally defined in terms of loyalty to the society within a specified area − is a key component of personal identity. National citizenship most readily comes to mind, but the term is also used at other levels of organization. Members of a tribe, residents concerned about watershed protection, and neighbors attending to local quality of life all qualify as citizens.
The concept of citizenship at the planetary scale is rather new, in part because our global governance infrastructure (environmental, geopolitical, and economic) is rudimentary. However, if there is to be a purposeful (teleological) attempt to mitigate and adapt to global environmental change, we residents of Earth must become planetary citizens.
Earth system scientists generally reject the Gaian notion that the planet is in some way self-regulating or purposeful. But if humanity indeed manages to join together and intentionally reverse the trend of rising greenhouse gas concentrations and mass extinction, the Earth system as a whole (Gaia 2.0) would in a sense gain purpose.
Embrace of planetary citizenship is a pushback against unbridled individualism. In the widely held neoliberal belief system, individuals are viewed most fundamentally as autonomous consumers who live in a biophysical environment that is a limitless source of materials and energy as well as a limitless sink for wastes. In fact, the human impact on the global environment is a summation of the resource demands from the 7.8 billion people who now inhabit the planet. The cumulative impact of humanity has clearly begun to induce changes in the Earth system that endanger both developing and developed nations.
Rights and Responsibilities
Planetary citizens have rights, in principle. As noted though, the global governance forums for establishing those rights are weak. In the realm of environmental quality, a planetary citizen certainly should have a right to an unpolluted environment.
Correspondingly, a planetary citizen’s responsibilities include understanding their own resource use footprint, and endeavoring to control it (e.g., having fewer children). Understanding the environmental impacts of their society and advocating in support of conservation-oriented governmental policies and actions (e.g., by voting) is also essential.
Because global change is happening so quickly and persistently, a commitment to lifelong learning about local and global environmental change is a foundation of planetary citizenship.
Identifying with any collective evokes a tension between personal autonomy and obligations to the greater good. Thus, the addition of planetary citizenship to personal identity creates psychological demands. Mental health requires that those new demands (e.g., pressure for less consumerism and more altruism) be calibrated to individual circumstances and to the state of the world.
Possibilities for the emergence of collective intelligence and agency among planetary citizens at various scales have grown rapidly as the Internet has evolved. Besides the general sense of a global brain emerging from the mass of online communication, various online groups now specifically address global environmental change issues, e.g. the MIT Center for Collective Intelligence sponsors a crowdsourced web site aimed at finding solutions to climate change.
Civil society organizations like 350.org, Millennium Alliance for Humanity and the Biosphere, and Wikipedia are testaments to the power of collective intelligence among planetary citizens. Participation of planetary citizens in self-organized groups of activists creates a sense of agency, which can be hard to find when a person confronts the enormity of global environmental change on their own. What is glaringly missing is a planetary forum for global environmental governance, something like the proposed World Environment Organization.
It is worth making a distinction between planetary citizenship and global citizenship. Both concepts are relevant to building global sustainability, with planetary citizenship more focused on the biophysical environment and global citizenship more concerned with human relationships.
Global Citizenship is often discussed in the context of Global Citizenship Education (GCE). GEC theory commonly calls for “recognizing the interconnectedness of life, respecting cultural diversity and human rights, advocating global social justice, empathizing with suffering people around the world, seeing the world as others see it and feeling a sense of moral responsibility for planet Earth”.
Traditional GCE theory may be oriented around experiential learning by way of immersive experiences in other cultures, often including volunteer work. However, persistent concerns that the relationship of visitor to host replicates the colonial model of dominance have led to more critically oriented versions of GCE theory. Here, the emphasis is on examining injustices and power differentials among social groups and evaluating effective means to foster greater equity.
The thrust of the global citizenship concept tends towards differentiating the parts of humanity and fulfilling the obligation to address injustices of all kinds; the thrust of planetary citizenship is on humanity as a collective entity playing a role in Earth system dynamics. A comprehensive approach to teaching global citizenship would emphasize both aspects and even transcend them.
Since identity as a planetary citizen is a choice, the question of how education can be designed to foster that choice is significant.
The idealized outcome of education for planetary citizenship is a human being who understands the impacts of the technosphere on the Earth system and has a willingness to engage in building global sustainability (Go Greta Thunberg!). These individuals would share a sense of all humans having a common destiny.
Two disciplines are particularly relevant.
The field of Big History covers the history of the universe leading to the current Earth system. It juxtaposes cosmic evolution, biological evolution, and cultural evolution to give perspective on how humanity has become aware of itself and come to endanger itself. A recently developed free online course in Big History aimed at middle school and high school students nicely introduces the subject. My own text, The Green Marble, and my blog posts such as A Positive Narrative for the Anthropocene, examine Big History at a level suitable for undergraduate and graduate students.
The field of environmental sociology is likewise important. It explores interactions of social systems with ecosystems at multiple spatial scales. The concept of a socioecological system, composed of a specific ecosystem and all the relevant stakeholders, is a core object of study. Nobel prize winning economist Elinor Ostrom helped elucidate the optimal structural and functional properties of socioecological systems at various scales.
Identifying as a planetary citizen means seeking to understand humanity’s environmental predicament and trying to do something about it. An important benefit from this commitment is the acquisition of a sense of agency regarding global environmental change. The aggregate effect of planetary citizenship across multiple levels of organization (individual, civil society, nation, global) will be purposeful change at the planetary scale.
Earth system scientists think of planet Earth as composed of multiple interacting spheres. The cryosphere is a term given to the totality of frozen water on Earth – including snow, ice, glaciers, polar ice caps, sea ice, and permafrost.
The cryosphere has a significant effect on the global climate because snow and ice largely reflect solar radiation, hence cooling the planet.
The multiple glacial-interglacial cycles over the last several million years were initiated by changes in sun/earth geometry (the Milankovitch cycles), but strengthened by changes in snow/ice reflectance along with changes in greenhouse gas concentrations.
Besides the positive feedback to climate change by way of reflectance effects (and release of greenhouse gases from permafrost melting), the diminishment of the cryosphere will have profound impacts on the technosphere.
The circulation of water through the hydrosphere on land is regulated in many cases by accumulation of snow and ice on mountains. That water is subsequently released throughout the year, thus providing stable stream flows for downstream irrigated agriculture and urban use.
The melting of glaciers and the polar ice caps will drive up sea level. If all such ice is melted (over the course of hundreds to thousands of years), sea level is projected to rise 68 m. The magnitude of sea level rise projected over the next 100 years for intermediate emissions scenarios is on the order of one meter.
Efforts to reduce greenhouse gas emissions will certainly slow the erosion of the cryosphere and should be made. The precautionary principle suggests we avoid passing tipping points associated with melting of the Greenland ice cap and the Antarctic ice cap. However, the momentum of environmental change is strongly in that direction.
Once these ice caps are gone, there is a hysteresis effect such that the ice does not return with a simple reversion to the current climate (e.g. by an engineered drawdown of the CO2 concentration).
The planet is headed towards a warmer, largely ice free, condition. The biosphere has been there before. The technosphere has not. Humanity will be challenged to develop adequate adaptive strategies.
Humanity is beset by global scale problems, notably climate change, pandemics, and geopolitical struggles.
Clearly, global scale solutions and – broadly stated – more global solidarity are needed.
The most obvious factor currently binding together nearly all humans and nations on the planet is the global economy. That economy is rooted in capitalism, albeit in various forms (e.g., free market capitalism, crony capitalism, state capitalism, and monopoly capitalism). Thus, capitalism is a logical place to look for both the source of our global scale problems and perhaps even, in its reform, solutions to those same problems.
The ubiquity of capitalism is not in doubt. Its characteristic feature is a market that allows for competitive exchange of goods and services. Legal support for accumulation of capital and its investment in profit making enterprises is foundational. In recent decades, capitalism has taken on a global character, featuring globalization of the labor market and capital flows.
The upsides of national level and globalized capitalism include efficiency in the distribution of goods and services, economic growth to support rising standards of living, and the availability of capital for investment in productive enterprises.
This blog post is primarily concerned with the relationship of capitalism to the global environment.
The impact of capitalism on the global environment traces back to its fundamentals. A capitalist organizes labor to manipulate natural resources and create products, which can then be sold in a competitive market. Income from product sales pays for the costs of production, for personal or corporate profit, and possibly for expansion of production.
Key problems with respect to the environment lie in the propensity for expansion and the pressure to minimize costs.
Because of the competitive nature of capitalism, producers are compelled to expand. More profits mean more capital to invest in beating competitors. Expansion tends to allow economies of scale that help minimize costs, hence increase competitiveness. However, production cannot expand indefinitely on a finite planet. Graphic examples include unsustainable use of ground water for irrigated agriculture, and unchecked conversion of rain forests to soybean fields.
Minimizing costs often means externalizing environmental costs. Greenhouse gases such as carbon dioxide are freely emitted as a byproduct of the fossil fuel combustion that powers much of the modern economy. The emitter does not pay the cost of climate change impacts. Economic globalization makes the externalization of environmental costs easier by shifting production to countries with relatively weak regulation of pollution.
It is time for a global scale reckoning of capitalism, in all its forms, with the fact that nearly eight billion people and a biosphere need to co-exist on what has become a crowded, rapidly warming, planet. Capitalism clearly causes environmental problems that it cannot solve.
Despite the fact that global climate change “changes everything”, capitalism is not going to go away. A primary mechanism by which to modify capitalism is policy changes at the level of the nation-state. Historically, the relationship of western capitalism to the state has undergone several major transformations – and the time is now for the next reset.
A very brief history of that relationship runs as follows.
The Capitalist State arose in the 19th century in association with the Industrial Revolution. This type of state strongly supported rapid expansion of capitalist enterprises but displayed limited concern for workers or the environment.
Reaction to inequality in wealth and overexploitation of workers led eventually to the Welfare State in which government expanded and supported provision of decent wages, health care, and old age income (e.g., the New Deal in the U.S.). By the 1960s, the issue of environmental quality also began to be considered a governmental responsibility.
By around 1980, the Neoliberal State (think Reaganomics) began to replace the welfare state. Here the size of government shrank, i.e., lower taxes and less regulation. Capitalists were again given free rein to maximize profits.
The appropriate transformation at this point is from the Neoliberal State to the Green State. Governmental concern for the environment must rise to the level of its concern for economic, security, and social welfare issues. The economic system is then seen as embedded in a society and constrained by the local and planetary ecology. If the goal is a sustainable Earth system, governments will have to increasingly intervene in the economic system to moderate capitalism’s worst excesses.
The transformation to Green States will require well educated citizens who share environmental friendly values, reformed corporate governance, and leaders who employ government to protect rather than exploit common pool resources (e.g. a carbon tax).
Note that economic inequality and environmental quality are linked by the notion that people who are not materially secure are not in a position to support potentially costly policies that improve environmental quality. Consequently, redistribution of income and wealth to improve material security are critically important – not only for the sake of social justice but also for the sake of the environment. More ominously, highly skewed distributions of wealth are historically associated with violent conflict, which often has adverse environmental consequences.
Moderating the impacts of capitalism on the global environment will require innovations in Earth system governance that parallel the transformations at the nation-state scale. The institutions of global geopolitical governance, economic governance, and environmental governance must be redesigned and empowered to protect the global environment. Thus, we might speak of fostering a green planet (or Green Marble as I have termed it). The vision of a Global Green New Deal from the United Nations outlines some steps that will move us in that direction.
A remarkable speculation is now circulating in the cybersphere to the effect that global emissions of carbon dioxide (CO2) from fossil fuel combustion may have peaked in 2019. Considering that recent formal projections generally indicate increasing emissions through 2030 or longer, this assertion is striking. It matters because CO2 emissions determine the growth in the atmospheric CO2 concentration, which in turn influences the magnitude of global warming.
The atmospheric CO2 concentration is currently 415 ppm (up from a preindustrial value of around 280 ppm) and is rising at a rate of 2-3 ppm per year. The consensus among climate scientists is that rapid greenhouse-gas-driven climate change will be harmful to the human enterprise on Earth. It would be good news indeed if CO2 emissions were on the way down.
Estimates for annual global CO2 emissions are produced by assembling data on consumption of coal, oil, and natural gas, as well as data on production of cement, which also releases CO2 (the sum is termed Fossil Fuel & Industry emissions). Deforestation is another significant anthropogenic source of CO2, but it is not considered in this blog post except to say that reducing deforestation will further reduce total CO2 emissions.
The suggestion that we are passing peak fossil fuel emissions is based on several observations.
1. The rate of increase in global emissions has been low in recent years, averaging less than 1% per year for 2010-2018. CO2 emissions are falling in the US and the EU, and the annual rate of increase in emissions is declining in India.
Covid-19 related reductions in global fossil fuel consumption for 2020 will be 7% or more. Emissions will likely rebound to some degree as the pandemic recedes but perhaps not fully.
3. Peak oil use may have occurred in 2019. Global demand in 2020 will fall about 10% because of Covid-19. Structural changes such as reduced commuting and business-related flying mean that some of the demand reductions will be persistent. Vehicles powered by electricity and hydrogen rather than gasoline are on the ascendancy, sparked in part by governmental mandates to phase in zero emissions vehicles.
4. Even a near term peak in natural gas consumption is being discussed. Again, the price advantage of renewable sources will increasingly weigh against fossil-fuel-based power plants. Ramped up production of renewable natural gas could substitute for fossil natural gas in some applications.
Surprisingly, it appears likely that a long-term decline in total fossil fuel use will be driven more by lack of demand than lack of supply.
Emissions from cement manufacturing are still climbing and amount to about 4% of total fossil fuel emissions. However, a recent study suggests that the CO2 uptake from slow weathering of aging cement around the world is providing a large offset (more than half) to current cement manufacturing emissions. Innovative uses of wood and geopolymers can potentially replace cement in many construction applications.
The election of Biden to the U.S. presidency is also relevant. Biden’s leadership will return the U.S. (largest cumulative CO2 emissions on the planet) to the international fold with respect to climate change mitigation. President Xi Jinping of China (largest CO2 emitter on the planet) has also displayed leadership (in words if not deeds) on the climate change issue. A revitalized collaboration between the U.S. and China on climate change mitigation could push the needle on global emissions reduction.
Currently about half of fossil fuel CO2 emissions remain in the atmosphere, with the remainder sequestered on the land (e.g. in vegetation and soil) and in the ocean. Once fossil fuel emissions begin decreasing and fall by half − and assumingthenet effect of increasing CO2 and climate warming is still substantial carbon uptake by the land and ocean − the atmospheric CO2 concentration will peak and begin to decrease. The year of peak CO2 concentration could be as early as 2040 (see carbon cycle projection tool below).
There is of course plenty that might go wrong. The net effect on the land and ocean sequestration just referred to could be a decline in carbon uptake. On land, carbon sources such as permafrost melting and forest fires will be stimulated by climate warming. In the ocean, warming will intensify stratification, thereby reducing carbon removal to the ocean interior.
Whatever specific years do turn out to be peak CO2 emissions and peak CO2 concentration, they will be remembered as historic hallmarks in humanity’s effort to address an existential threat of its own making.
Recommended: Interactive CO2 Emissions and Concentration Projection Tool.
In the discipline of Earth System Science, a useful analytic approach to sorting out parts and wholes is by reference to the earthly spheres. The pre-human Earth system included the geosphere, atmosphere, hydrosphere, and biosphere. With the biological and cultural evolution of humans came the technosphere. In a very aggregated way of thinking, these spheres interact.
The biosphere is the sum of all living organisms on Earth; it is mostly powered by solar radiation and it drives the biogeochemical cycling of elements like carbon, nitrogen, and phosphorus.
The technosphere is the sum of the human enterprise on Earth, including all of our physical constructions and institutions; it is mostly powered by fossil fuels and it has a large throughput of energy and materials.
Over the last couple of centuries, the technosphere has expanded massively. It is altering the biosphere (the sixth mass extinction) and the global biogeochemical cycles (e.g. the CO2 emissions that drive climate change).
The interaction of the technosphere and the biosphere is evident at places like wildlife markets where captured wild animals are sold for human consumption. Virologists believe that such an environment is favorable to the transfer of viruses from non-human animals to humans. The SARS-CoV-2 virus likely jumped from another species, possibly wild-caught bats, to humans in a market environment. Covid-19 (the pandemic) has now spread globally and killed over one million people.
The human part of the technosphere has attempted to stop SARS-CoV-2 transmission by restricting physical interactions among people. The summed effect of these self-defense policies has been a slowing of technosphere metabolism. Notably, Covid-19 inspired slowdowns and shutdowns have driven a reduction in CO2 emissions from fossil fuel combustion and a decrease in the demand for oil. This change is of course quite relevant to another interaction within the Earth system − namely technosphere impacts on the global climate.
There are important lessons to be learned from technosphere response to Covid-19 about relationships among the Earthly spheres.
One lesson regards the degree to which the technosphere is autonomous.
If we view the technosphere as a natural product of cosmic evolution, then the increase in order that the technosphere brings to the Earth system has a momentum somewhat independent of human volition. The technosphere thrives on energy throughput, and humans are compelled to maintain or increase energy flow. It is debatable if we control the technosphere or it controls us.
In an alternative view, tracing back to Russian biogeochemist Vladimir Vernadsky in the 1920s, humanity controls the technosphere and can shape it to manage the Earth system. This view received a recent update with a vision of Gaia 2.0 in which the human component manages the technosphere to be sustainably integrated with the rest of the Earth system.
The fact that humanity did, in effect, reduce technosphere metabolism in response to Covid-19 supports this alternative view.
Admittedly, the intention in fighting Covid-19 was not to address the global climate change issue. And the modest drop in global carbon emissions will have only a small impact on the increasing CO2 concentration, which is what actually controls global warming. Nevertheless, the result shows that it is possible for human will to affect the whole Earth system relatively quickly. The Montreal Protocol to protect stratospheric ozone is more directly germane.
A second lesson from technosphere reaction to Covid-19 is that a technosphere slowdown was accomplished as the summation of policies and decisions made at the national scale or lower (e.g. slowdowns/shutdowns by states and cities, and voluntary homestay by individuals). The current approach to addressing global climate change is the Paris Agreement, which similarly functions by way of summation. Each nation voluntarily defines its own contribution to emissions reduction, and follow-up policies to support those commitments are made at multiple levels of governance. This bottom-up approach may prove more effective than the top-down approach in the unsuccessful Kyoto Protocol.
A third lesson from technosphere response to Covid-19 regards the coming immunization campaign to combat it. Many, if not most, people around the planet will need to get vaccinated to achieve widespread herd immunity. Success in addressing the climate change issue by controlling greenhouse gas emissions will likewise depend on near universal support at the scale of individuals. Education at all levels and media attention are helping generate support for climate change mitigation. Increasing numbers of people are personally experiencing extreme weather events and associated disturbances like wildfire and floods, which also opens minds. The political will to address climate change is in its ascendency.
The response of the technosphere to biosphere pushback in the form of Covid-19 shows that the technosphere has some capacity to self-regulate (i.e. to be tamed from within). Optimally, that capability can be applied to ramp up a renewable energy revolution and slow Earth system momentum towards a Hothouse World.
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.
A key pursuit in the field of Earth System Science is measuring and monitoring global scale structures and processes. These measurements have led to the concept of the “Great Acceleration”, a name given to the period since around 1950 during which many global scale attributes related to the human enterprise (the technosphere) began rising in an exponential fashion. The increase in global population is the iconic example.
Intuitively, it seems unlikely that this level of population increase and associated resource consumption could continue indefinitely on a finite planet. Practically speaking, problems have begun to arise both with resource shortages and environmental degradation from excess waste production (e.g. global warming and ocean acidification from massive fossil fuel combustion).
Humanity clearly must transition to a more sustainable relationship with the rest of the Earth system. The way forward lies in bending those exponentially rising Great Acceleration curves for population and resources use, hitting the peaks, and engineering declines.
As noted by ecologists long ago, total resource use (Impact) is a function of the number of people (Population), their per capita use (Affluence), and the efficiency with which raw resources are converted to useful products (Technology).
Resource use per person obviously varies tremendously, hinting at the special responsibility of the more developed countries to limit population growth (the net effect of births minus deaths and immigration minus emigration). But all humans consume natural resources. Thus, the high projected population growth rates in less developed countries must also be brought down. The sooner global population peaks, the less natural capital (e.g. biodiversity) will be degraded, the less likely that competition for resources will lead to human conflict, and the less likely that climate change will trigger tipping points in the Earth system that precipitate extreme impacts on humans.
Past, Present, and Future Global Population
The global population size doubled between 1927 and 1974 and has nearly doubled again since 1979. It is now 7.8 billion.
However, the rate of annual global population growth has fallen in recent decades (from > 2% per year to 1.05% per year), mostly associated with a decreasing trend in fertility (children born per woman during her reproductive lifetime).
However, recent research points toward lower values, possibly a peak of 9.7 billion around 2064 and a decline to 8.8 billion by 2100.
Factors Influencing Demographic Projections
Projections of peak global population have significant policy implications. Relatively low estimates may have the effect that national commitments to stabilize population are downgraded and that overhyped media accounts of depopulation sap political will to continue family planning programs. Relatively high estimates for peak global population foster the impression that humanity it doomed to an overcrowded and overheated planet, hence favoring lifeboat ethics.
Despite the critical implications of their results, the models used to predict peak population are very sensitive to the assumptions made about trends in fertility.
The recent lower estimates for peak global population rely on continued or increasing reductions in fertility in the high fertility countries. But demographers in the past have sometimes overestimated declines in fertility, and may be doing so now as well. Historic trends of declining fertility have stalled in some high fertility countries, possibly related to falling support for family planning. The Catholic Church still formally prohibits artificial birth control.
Nevertheless, several emerging trends may support lower projected peaks in global population.
One is that efforts to shift cultural norms favoring large family size increasingly include family planning messaging in popular media (e.g. serial dramas), which are having significant success with both genders.
The Covid-19 pandemic could push birth rates down (at least in the more developed countries) because financial insecurity will dispose women in developed and developing countries to postpone or forgo having children.
Mortality rates may also be higher than expected. Life expectancy has generally increased in recent decades throughout the world. Much of that increase is associated with reduced child mortality but increasing longevity is also a factor. However, life expectancy in the U.S. went down from 2014 to 2017 because of increasing fatal drug overdoses and suicides. Climate change is expected to bring an increase in extreme weather events causing mortality directly (as in flooding), and indirectly by way of impacts on agriculture and possibly the incidence of war.
Implications Beyond Absolute Population Size
A leading concern about a rapid peak and then decline in national populations is the associated increase in the ratio of older retired people to younger working people. As the population ages, the number of active workers available to support each elderly person tends to decline. Hence, taxes may have to be increased to provide income and health care to the elderly. Various mitigating factors include the improving health of elderly people, significant intergenerational transfers of wealth, increases in labor force participation by the elderly, and volunteer efforts by the elderly.
A decline in the number of children per family can have many beneficial side effects including: 1) more resources (parental attention and ability to finance education) per child, 2) improved quality of life for parents (less stress and more free time), and 3) rising per capita income.
The sooner global population peaks and begins to decline, the greater the possibilities for achieving global sustainability. Since about 40% of pregnancies globally are still unplanned, a primary tool for insuring children are born into a welcoming and opportunity-rich environment is continued and improved provision of family planning support in both the developing and developed world. More political will and contributions to NGOs are needed. At this point in human history, the local and global challenges (environmental, economic, and social) that arise from a stable or declining population are likely more manageable than those arising from high rates of population growth.
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 complimentary; 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)
Earth’s biodiversity is under siege by the global human enterprise (the technosphere). Most species will survive into the distant future, possibly a future in which the human population has shrunk, and the value of biodiversity is more widely appreciated. But many species will go extinct along the way.
Biologist E.O. Wilson and others have evoked the image of a bottleneck in this context (Figure 1). A bottleneck implies a tightening of constraints on flow. In the case of the biodiversity bottleneck, flow refers to the survival of species through time.
As the future unfolds and the technosphere continues to grow, the possibilities for species to pass through the biodiversity bottleneck diminish. But there is a lot of room for maneuver here. A worthy project for humanity – especially over the next few decades − is to keep that bottleneck as wide as possible. After passing through it, global biodiversity may recover to some degree as the technosphere begins to weigh less heavily on the biosphere. It all depends on us.
Evidence of human impacts on biodiversity surrounds us. Comparisons of current rates of extinction and those in the fossil record indicate that vertebrate species are now going extinct at a rate 100 or more times faster than is observed in most previous geologic periods. The human-driven Sixth Extinction began perhaps 50,000 years ago when primitive humans arrived on Australia and wiped out many prey species that were unfamiliar with the new bipedal super predator. Anthropologists refer to the “Pleistocene Overkill” to describe the wave of mammal extinctions that occurred when humans first crossed from Asia to North America about 15,000 years ago.
Modern humans continue to exterminate species directly by overhunting for food (e.g. the passenger pigeon) but also by widespread trafficking in wildlife and animal parts for food, as well as for medicinal and prestige purposes. Various plant species are also endangered, notably several tropical hardwoods known as rosewood. Sustained pressure on wildlife habitat from land use change and disruptions in geographic ranges caused by climate change adds further stress on top of overexploitation. Genetic variation within many species is shrinking as their populations and geographic ranges contract, hence reducing their capacity to survive environmental change (formally termed a population bottleneck).
In essence, the expansion of technosphere capital (the mass of human made objects) is consuming biosphere capital (the biodiversity and biomass of the biosphere). This loss of biodiversity − usually defined in terms of diversity of species and ecosystems − will likely continue over the coming decades. As noted, though, the magnitude of the loss will depend heavily on human decisions.
There are pragmatic, aesthetic, and ethical rationales for conserving Earth’s biodiversity. Conservationists argue that retaining biodiversity maintains the functional integrity of ecosystems, and hence the full array of their ecosystem services. Each species has a unique niche and contributes to ecosystem processes like nutrient cycling and recovery from disturbances. With respect to aesthetics, the earlier mentioned Professor Wilson has suggested that humans have genetically determined biophilia − we get spontaneous pleasure from interacting with diverse forms of life. The ethical argument is made strongly by the Deep Ecology movement. For supporters, there is no human exceptionalism – all species have an equal right to survive and prosper on this planet.
Given the multiple rationales for wishing to widen the biodiversity bottleneck, what collective actions (besides the overriding one of limiting climate change) can help? Scientists and policy experts have identified biodiversity-friendly practices such as reducing pesticide use, buying certified products, reducing invasive species, and reducing water pollution. But here are four others that have high relevance.
1. Stop Trafficking in Wildlife and Wild Animal Parts
The global trade in wild animals and wild animal parts puts tremendous downward pressure on the populations of many species. Wild animals are commonly sold in Southeast Asian food markets despite laws against it. Tigers, rhinos, and pangolins continue to be poached for dubious medicinal purposes. Wild caught animals are sold as “bush meat” in parts of Africa and South America.
A global trade in live animals intended as pets also flourishes. Millions of songbirds are collected every year in the primary forests of Indonesia and sold as pets or trained as contestants in bird song competitions. Tropical fish are collected in the wild for marketing to aquarium owners.
Multiple international agreements aim to stem wild animal trafficking, especially the Convention on International Trade in Endangered Species of Wild Fauna and Flora. Under its auspices, national law enforcement agencies regularly confiscate illegal shipments of wild animals, animal parts, and wood from endangered tree species. However, these efforts face deep resistance for cultural and economic reasons.
A new brake on wild animal trafficking is fear of zoonotic pathogens. The SARS-CoV-2 virus that is causing the Covid-19 global pandemic likely jumped from a wild animal host to a human in a market where wild animals are sold illegally. New legislation passed in China limits sales of wild animal meat. Unfortunately, enforcement is spotty, and the new law still allows sales of wild animal parts for medicinal purposes. Sustained international pressure on wildlife traffickers is needed.
The Covid-19 pandemic is apparently impacting wildlife protection in other ways. Conservationists fear that the loss of the tourist ‘halo’ or proximity effect, because of Covid-19 shutdowns, will increase the incidence of poaching in nature reserves. Resumption of tourism would help in that regard.
2. Expand the Size and Number of Protected Areas
A key driver of declining biodiversity is habitat loss. To bring as many species as possible through the biodiversity bottleneck will require protection of representative areas for all unique types of ecosystems.
The Rewilding Movement has argued for creating protected areas that are large enough to support the whole complement of native species characteristic of each ecosystem type, along with the entire range of abiotic processes such as floods and fires that help maintain it.
Presently, about 15% of global land plus inland waters is protected to some degree. For the oceans within national jurisdictions, the figure is about 13%. Not all ecosystem types are represented. For many types of ecosystems, the current protected area is quite small relative to its original geographic distribution (e.g. the Atlantic rain forest in Brazil).
Protected area plans can be developed over large domains, e.g. the entire United States. These plans rely on integration of different managed lands such as wilderness areas, national parks, national forests, urban areas, and private reserves.
An international scientific advisory body (IPBES, Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services) is dedicated to biodiversity assessment and conservation. Like the Intergovernmental panel on Climate Change, IPBES produces periodic assessments and examinations of policy options. IPBES is supported by member countries, including the U.S., and sustained national contributions are warranted.
In the private sector, land trust organizations such as The Nature Conservancy have as their key strategy the purchase of lands for conservation purposes; contributions are encouraged. Public/private conservation partnerships are proliferating; participants are welcomed.
3. Design Sustainable Cities
The proportion of the global population that lives in an urban setting recently passed the 50% mark and is expected to keep climbing in the coming decades. A potential benefit to biodiversity conservation lies in the land that is abandoned as people supported by subsistence agriculture and nomadic herding move to towns and cities. The freed-up land can potentially be repurposed in part or whole for wildlife conservation. An underlying assumption is that agricultural intensification can take up any slack in food production and keep everyone fed.
Urban greenbelt areas, parks, and gardens may serve directly as another assist to biodiversity conservation. They support native and alien species and could serve as refuges for plant and animal species that are extirpated regionally by climate change and land use change. Urban rivers and streams can likewise be managed to protect and support wildlife.
4. Strategically Increase Ecotourism
In theory, the local economic benefits of nature-based tourism inspire local conservation efforts. However, high tourist demand produces pressure to increase supply. More local economic development (e.g. hotels and restaurants) plus more intensive visitor utilization of natural resources may end up degrading local ecosystems. The research literature contains ecotourism case studies of successes, as well as failures.
Ecotourism narrowly defined refers to tourism that allows visitors to experience local wildlife and landscapes, creates incentives to protect those organisms and landscapes, and supports local communities. More ecotourism is probably not appropriate in many places where it already exists because capacity is limited. Rather, it is needed where wildlife is under threat and conservation incentives might be effective.
Building socio-ecological systems is an emerging route to local sustainability. These stakeholder groups optimally self-regulate to conserve the economic health and ecological health of the local environment. Nobel Prize winner Elinor Ostrom has developed principles for structuring and operating these groups. Monitoring the social, economic, and ecological dimensions of sustainability is a key requirement for successful ecotourism management.
Air travel is the foundation for much tourism, but it is especially difficult to decarbonize. Short hop electric airplanes and long-haul flights powered by renewable energy based liquid fuels are technically feasible. They could replace fossil fuel powered flights, but more government supported research is needed, and air travelers must be willing to pay an increased fare as these fuels are brought online. Airline-associated carbon offset programs − although varying in effectiveness and not a permanent solution − contribute significantly to biodiversity conservation. They help expand protected area and, by sequestering carbon, help slow climate change.
The human capacity to extinguish other species on this planet, and to pervasively alter wildlife habitat, means that we are in many ways responsible for which species and ecosystems will survive. As we move through peak human population this century and begin to more purposefully manage our impacts on Earth’s biota, let’s keep the biodiversity bottleneck of our own making as wide open as possible. Progress towards that goal would be both pragmatic and gratifying.