A surprising outcome emerged from the March meeting of the Subcommission on Quaternary Stratigraphy (within the International Union of Geological Sciences). The surprise came in the form of a vote regarding the official status of the Anthropocene concept, with a majority of the subcommission members voting against a proposal to identify the Anthropocene as a new geological epoch.
The term Anthropocene was originally inspired by the observation that the impacts of the human enterprise on Earth’s environment ̶ notably a rise in the atmospheric CO2 concentration ̶ have begun to rival those of the background geologic forces. Since divisions of the geologic time scale are generally associated with major changes in the global environment, naming a new epoch was a reasonable suggestion.
The formal proposal to do so came from the multidisciplinary Anthropocene Working Group (AWG), which has deliberated on the issue for the last 14 years. The AWG proposal specified that the Anthropocene be named a new epoch, with a beginning point in the early 1950s. Its stratigraphic marker was to be a layer of chemical residues from post-World War II nuclear weapons testing.
The Vote
The vote against designating the Anthropocene as a new Epoch was a surprise because the proposal had been made with a strong scientific foundation and had a lot of support. The decision against the proposal was not because the Anthropocene is geologically insignificant, but rather because the Anthropocene concept is highly significant to many disciplines besides geology. In the last 20 years, the concept has received widespread attention in both academia and popular media. Indeed, the term has taken on a life of its own, a life outside the staid world of Quaternary Stratigraphy.
The term Anthropocene has come to signify a rupture in human history ̶ the end of a time when the biophysical environment was mostly a background to the march of human progress. The rupture is evident from a suite of global indicators, ranging from oil consumption to the rate of deforestation, that all began rising dramatically in the last 100 years. The word Anthropocene now has broad cultural significance; it implies that humanity has acquired a new responsibility to self-regulate, or face its own demise from a self-induced inhospitable environment.
The negative vote within the subcommission was also based on a more technical issue about whether, considering that humans have been altering the environment at many scales for many thousands of years, the beginning of the Anthropocene Epoch could be narrowed down to the early 1950s.
An alternative proposal, with considerable cross-disciplinary support, is to designate the Anthropocene a geologic “event”. This term is used in the geosciences to reference a wide variety of Earth system changes or transformations. Designating something as an event does not require the kind of formal approval process associated with designating an epoch.
The Scope of the Anthropocene Event
Despite this quasi-downgrade to Event status, the Anthropocene has really just begun and will ultimately have a massive impact on the Earth system. The Anthropocene Event, as we will call it here, will eventually push the global mean temperature up 2-3 oC or more, a range associated with the early Pliocene Epoch 3-5 million years ago (Figure 1). Because of human influences on the atmosphere, Earth may well miss its next scheduled glacial period (as prescribed by the Milankovitch solar forcings).
Figure 1. The geologic record of global mean temperature, with projections to 2100. The x-axis units differ by panel. The graphic is adapted from work by Glen Fergus.
What is also quite extraordinary is that the Anthropocene Event is concurrent with the origin of a whole new Earth system sphere – the technosphere. This term refers to the accumulation of human artifacts ̶ including buildings, transportation networks, and communication infrastructure ̶ that now cloaks the surface of the Earth.
From an Earth system science perspective, the parts of the Earth system are its spheres, i.e. the lithosphere, atmosphere, hydrosphere, cryosphere and biosphere interact with each other over geological time to determine the state and dynamics of the Earth system.
The biosphere (defined by geochemists as the sum of all life on Earth) is of particular interest here. The biosphere did not exist early in Earth’s history, but after the origin of life and its proliferation around the planet, the impacts of the biosphere on Earth’s energy flow and chemical cycling became profound (e.g. the oxygenation of the atmosphere).
The Role of the Anthropocene Event in Cultural Evolution
Transition to global sustainability will require the emergence and evolution of a global culture, i.e. a globally shared set of beliefs and practices. The Anthropocene Event is a concept that can help anchor a robust integration of human history and Earth history.
In light of the need for broadly unifying concepts related to global environmental change, I think the geologists made the right call. The Anthropocene has become a politically potent idea and deserves the widest possible attention in the domains of scholarship, education, entertainment, and advocacy.
The universe is vast, and appears to be order-friendly. Astrobiologists ̶ who study the phenomenon of life in the universe ̶ have thus concluded that life has likely arisen spontaneously on many planets. The recurrent emergence of intelligent life by way of natural processes is also considered plausible.
That we expect planets inhabited by intelligent creatures to be plentiful, but have not encountered any, is referred to as the Fermi Paradox. The explanation may lie simply in the vast distances involved relative to the speed of light and how long we have been looking. However, this silence also raises a question about possible factors that could constrain the development of exoplanetary, advanced-technology, civilizations.
Astrobiologists have designated the constellation of factors that could prevent the evolution of a civilization capable of interstellar communication as “The Great Filter”. The supposition here is that there are many crucial steps along the way, and only rarely would they all fall into place. Some of the crucial roadblocks are the origin of life in the first place, the biological evolution of complex multicellular organisms, and the cultural evolution of technologically advanced societies.
To help us think about patterns in planetary evolution, astrobiologists refer to the possibility of technospheres as well as biospheres. A biosphere comes into existence on a planet when the summed biogeochemical effects of all living organisms begins to significantly affect the global environment (e.g. the oxygenation of Earth’s atmosphere around 2.5 billion years ago). A technosphere comes into existence when the summed biogeochemical effects of all the material artifacts generated by a highly evolved (probably self-aware) biological species begins to affect the global environment (e.g. the recent boost in the CO2 concentration of Earth’s atmosphere). Like a biosphere, a technosphere maintains a throughput of energy (such as fossil fuel) to power its metabolism, and a throughput of materials (e.g. minerals and wood) to maintain and grow its mass.
Earth’s biosphere has existed for billions of years and operates in a way that its influence on the global environment tends to keep the planet habitable (the Gaia Hypothesis). Reconciling this mode of operation with Darwinian evolution is controversial, but Earth system scientists have proposed that components of the biosphere (i.e. guilds of organisms that perform particular biogeochemical cycling functions) have been gradually configured and reconfigured (by chance in combination with persistence of favorable states) into a planetary biogeochemical cycling system with sufficient negative feedback processes to maintain the habitability of the planet.
In contrast to the biosphere, Earth’s technosphere exploded into existence quite recently and has grown wildly since its inception. Few negative feedbacks to its growth have yet evolved. Possible causes for truncated efforts towards a long-lived technosphere include factors such as apocalyptic warfare (a nuclear winter), pandemics, AI related take downs, and environmental degradation. Any of these could qualify as the Great Filter.
The key impact of overexuberant technosphere growth on Earth is rapid global climate change induced by greenhouse gas emissions. A continued high level of these emissions could trigger a cascade of positive feedback mechanisms within the climate system that drive the global environment to a state fatal to the technosphere itself. That process may turn out to be the distinctive manifestation of the Great Filter on Earth.
The transition to a mature (sustainable) technosphere on Earth will require 1) recognizing the danger of rapid environmental change, 2) understanding what must be done to redesign the technosphere, and 3) organizing collectively (globally) to carry out a program of change.
Earth system scientists have gotten quite good at simulating the causes and consequences of global climate change. Thus, the scientific community recognizes the danger of uncontrolled technosphere growth and understands what must be done to avoid a climate change catastrophe.
But deliberately pushing our current technosphere through the sustainability phase of the Great Filter will require the difficult political work (within and between nations) of changing values and better organizing ourselves at the global scale.
If humanity does ever encounter extra-terrestrial intelligence, I imagine that it will stimulate global solidarity in an “us vs. them” context, and perhaps strengthen our willingness to work together on issues of global sustainability and defense.
As long as we do not encounter extra-terrestrial intelligence, we must face the enormous moral responsibility to conserve and cultivate our biosphere and technosphere as possibly unique, hence supremely valuable, cosmic experiments.
The technosphere is a component of the contemporary Earth system. Like the biosphere ̶ also an Earth system component ̶ the technosphere has a mass, requires a steady input of materials, and utilizes a throughput of energy.
Technosphere mass is composed of all human-made objects, including the mass of buildings, transportation networks, and communication infrastructure. That mass has built up over centuries, and is still accumulating at the rate of 3-5% per year.
The material inputs to the technosphere (besides fossil fuels) include food, water, wood, and minerals. These inputs are derived from the geosphere, hydrosphere, and biosphere ̶ often with destructive consequences. Upward trends in consumption of these inputs are associated with an upward trend in global Gross Domestic Product of about 3% per year.
The energy that drives technosphere metabolism comes mostly from fossil fuels (80%). Global fossil fuel consumption was increasing at a rate of about 5% per year (2009 – 2019) until the recent dip associated with the Covid-19 pandemic.
Earth system scientists have estimated both current technosphere mass (in use) and the current biosphere mass (i.e. including all microbes and multicellular organisms). Coincidentally, those numbers are of approximately the same magnitude (about 1018 g). However, technosphere mass is increasing substantially each year, while the multi-century trend in biosphere mass and diversity is towards a diminished and depauperate state. The technosphere is essentially now growing at the expense of the biosphere.
There are a few cases at the national scale where peak technosphere mass has been reached, albeit not specifically by design. In Japan, the number of automobiles is close to its peak and the length of pipelines and high-speed rail are not increasing. Ninety-two percent of the population is urban. Total energy use is declining. These trends can be traced to a high level of development and a declining population.
A low birth rate and a low level of immigration account for the decreasing population. As a case study, Japan points to the role of population size in stabilization of technosphere mass. Per capita technosphere mass is relatively high, but is not rising because the country is already highly developed. Hence, technosphere mass at the national scale has likely peaked. By 2050, population is projected to decline about 25% from its peak, which may allow for a decrease in national technosphere mass.
China is an interesting case at the other extreme of technosphere mass dynamics, with vast on-going growth of its technosphere mass. Despite a low birth rate, China’s population is still growing (slowly). More importantly, per capita wealth is increasing. Consequently, the number of people owning modern housing and an automobile is rising rapidly. The government is also making huge investments in infrastructure – notably in power plants and high-speed rail.
Humans do sometimes place limits on technosphere mass expansion ̶ as in the urban growth boundaries around cites in the state of Oregon (USA), and in areas of land and ocean that are in a protected status (e.g. wilderness areas in the U.S.). Idealized prescriptions for future land use include 30 X 30 and 50 X 50. These values refer to 30 percent of Earth’s surface dedicated to biosphere conservation by 2030, and 50% by 2050. Seventeen percent of land and ten percent of ocean are in a protected status at present.
These conservation goals are consistent with the strong global trend towards urbanization. Over half of humanity now lives in an urban setting, a proportion that is projected to rise to 66% by 2050. The key benefits of urbanization with respect to technosphere mass are that 1) it potentially frees up rural land for inclusion in biosphere protection zones, 2) the per capita technosphere mass of urban dwellers is less than that of equally wealthy rural dwellers (e.g. living in multiple unit buildings as opposed to living in dispersed separate building, and using public transportation rather than everyone owning an automobile), and 3) birth rates decline as people urbanize, which speeds the global demographic transition.
Peak technosphere mass will occur sometime after peak global population. That assumes global per capita technosphere mass will also peak eventually, which brings up the fraught issue of wealth inequality. Individual wealth is equivalent in some ways to individual technosphere mass (e.g. owning a yacht vs. owing a row boat). Given that there are biophysical limits to human demands on the Earth system, the nearly 8 billion people on the planet cannot all live like billionaires. From a humanist perspective, a wealth distribution that brings standards of living for everyone up to a modest level is desirable. That worthy principle is the guiding light for significant philanthropic efforts and should figure into policies related to taxation of income and wealth. Whether to explicitly attempt to reduce the ecological footprint of the wealthy is a related, and highly contested, question.
An estimate of technosphere mass that includes landfills, and other cases of human-made objects not in use, is much larger that the 1018g estimate of technosphere mass in use. Indeed, geoscientists looking for a depositional signal for the Anthropocene are considering discarded plastic as a marker. It will take a concerted effort to decrease material flows into landfills before we will see a peak in unused technosphere mass.
Peak Technosphere Input of Material Resources
Humans already appropriate around 25% of terrestrial net primary production, and divert 54% of available fresh water flows. Mining geosphere minerals for input to the technosphere covers approximately 57,000 km2 globally.
The concept of the Great Acceleration captures the problem of exponentially rising technosphere demands on the Earth system. It refers to the period since 1950 during which many metrics of human impact on the global environment have risen sharply (Figure 1). Obviously, those trends cannot continue. Humanity must bend those usage curves and redesign the technosphere to maintain itself sustainably.
Figure 1. The Great Acceleration refers to the period after 1950 when impacts of the technosphere on the global environment grew rapidly. Image Credit: Adapted from Welcome to the Anthropocene.
Some metrics, like wild fish consumption, have already peaked but that is because the resource itself has been degraded. Future increases in fish consumption will have to come from cultured sources.
Many rivers around the world are already fully utilized (and then some), e.g. the Colorado River Basin in Southwestern United States. Policies like tearing out lawns in Las Vegas to save water portend the future.
Global wood consumption increases several percent per year and is projected to continue doing so for decades. Much of current industrial roundwood production is from natural forests, sometimes in association with deforestation. Forest sector models suggest that high yield plantations in the tropical zone could supply most of the projected global demand for industrial wood, thus reducing pressure on natural forests.
Resource use efficiency can be increased by extending product lifetimes (e.g. automobiles), boosting rates of recycling (e.g. paper), and improvement in design (e.g. more efficient solar panels). Again, these changes must be made along with the stabilization of population if we are to end continuing growth of technosphere demand for natural resources.
In 2021, fossil fuel emissions roared back to about the level of 2019. Emissions in 2022 will likely be impacted significantly by the war in Ukraine, possibly reducing global emissions since moves to avoid purchasing Russian gas, oil, and coal are driving up prices for fossil fuels. Certainly, there is increased political support in the EU and elsewhere for rapid transition from fossil fuels to renewable energy sources. Technological constraints will slow the pace of that conversion, and emissions will continue to increase in many countries outside the EU (especially China and India). Thus, the actual peak year for global fossil fuel emissions is uncertain.
The faster that fossil fuel-based energy is replaced by renewable energy sources, the better chance of avoiding a climate change catastrophe. Multiple policy rationales, beside reducing carbon dioxide emissions, support the goal of a global renewable energy revolution.
Note that total energy consumption need not decline within the context of global sustainability if the energy sources are renewable. Projected peak global energy use – with accounting for increasing efficiency, population growth, and the curing cases of energy poverty – is on the order of current global energy use.
Conclusion
The sprawling mass of the technosphere, its demands on natural resources, and its flood of chemicals and solid waste into the global environment, have begun to diminish the biosphere and threaten human welfare on a massive scale. Humanity must begin to work as a collective to redesign technosphere metabolism such that it conforms to the biophysical limits of the Earth system.
In the case of hunter/gatherers, the human contribution to production of harvested food was limited. But as technology became more important in provision of ecosystem services, the human element (including machines and knowledge) began to dominate.
A problem has arisen because humans have tended to consume not only ecosystem services (flows) from natural capital, but also the nature-built capital (stocks) itself. A striking example is the cod fishery in the North Atlantic Ocean: overfishing led to a collapse of the cod population and an abrupt decline in productivity.
For centuries, humans have gotten away with depleting or destroying natural capital by simply moving on to the next unexploited natural resource. Commodity frontiers often have a geographic dimension, e.g. the wave of primary forest exploitation in temperate North America that extended from the New England hardwoods, through the pines of the Great Lakes states, and on to the Pacific Northwest conifers.
A massive erosion of nature-built capital over the last two centuries is evident in the spatial patterns of land use change, distortions in animal and plant population structure, and outright extinction of species. As natural capital is depleted, human interventions (often subsidized by energy from fossil fuels) must be ramped up to maintain the same level of ecosystem services.
From an Earth system science perspective, we can describe the interaction of the human enterprise and natural capital in terms of interaction of the technosphere with its natural resources base.
The technosphere is the global aggregate of human made artefacts and includes machines, buildings, transportation infrastructure, and communications infrastructure, along with the humans and their knowledge needed to maintain it. Estimates of technosphere manufactured capital are on the order of 800 Pg.
The technosphere requires a large stream of materials and energy to maintain itself and to produce the outputs of goods and services that keep the 7.8 billion people on Earth alive. Here, I am particularly interested in the interaction of the technosphere with the biosphere.
Biosphere capital is the sum of all organisms and the associated information in the form of genetic material. It is a subset of global natural capital.
Biosphere mass is estimated at 550 Pg (carbon) and the estimates for the number of species range from 5.3 million and 1 trillion. Inputs to the biosphere include solar energy and material flows from the geosphere (minerals) and hydrosphere. Besides sustaining itself, the biosphere outputs vast flows of food and fiber (including wood) to the technosphere.
From the global perspective, technosphere manufactured capital is clearly increasing and biosphere capital is clearly decreasing. Examples include:
Our limited understanding of the biosphere makes it difficult to even quantify the on-going loss of biosphere capital. Note that the biosphere contributes to regulation of atmospheric and marine chemistry by way of the global biogeochemical cycles. Thus, as we lose biosphere capital, we are beginning to lose those free regulatory services.
Meanwhile, technosphere manufactured capital is growing at a rate of 1-8% per year, depending on the level of development in a given country. It will likely peak at a much higher level than at present because of the still growing global population and increases in per capita manufactured capital in the developing world.
In principle, biosphere inputs to the technosphere can be derived in a sustainable manner. A landscape of tree plantations can be continuously harvested and replanted to produce a sustained yield of wood. Plantation forests supplied about one third of industrial roundwood in 2000. Likewise, there is such a thing as a sustainable marine fishery if the harvest is properly managed.
However, much of the current material transfer from biosphere to technosphere is drawing down biosphere capital. Differentiating between sustainable and depleting production of food and fiber, and increasing attention to sourcing, will play an important role in the transition to a soci-economic metabolism that is sustainable. Accounting practices that treat all forms of capital – including natural capital and technosphere capital in its various forms (manufactured, financial, human, social) – is necessary.
Since different natural resources must be managed at different scales, a hierarchy of socio-ecological systems is needed. This arrangement points to the importance of zonation on the Earth surface in terms of the strength of the coupling between technosphere and biosphere. We can have large areas of relatively undisturbed intact ecosystems (e.g. marine reserves and terrestrial wilderness areas), significant areas of heavy technosphere dominance (as in urban and industrial zones), significant areas of intensive food and fiber production (e.g. forest plantations), and a scattering of areas with a moderate intensity of biosphere/technosphere interaction. This view supports the development of spatially-explicit simulation models – implemented at a range of spatial scales – that can be used within a socio-ecological system to organize the co-production of ecosystem services. Potentially, with a well-designed combination of monitoring, modeling, and environmental governance, the technosphere will drive increases rather than decreases in biosphere capital (e.g. the recovery of whale populations).
Computer generated image of world-wide internet connections. Image credit: The OPTE Project
David P. Turner / November 14, 2021
The threat of anthropogenically-induced global environmental change imposes a challenge on humanity to reconceptualize its relationship to the other components of the Earth system. Historically, Nature was the background for the human enterprise. It provided unlimited sources of ecosystem services, such as ocean fish, clean air, and clean water. However, as the human enterprise expanded – especially after the “Great Acceleration” of technological development beginning about 1945 – real limits have become obvious.
Because the sum of human impacts on the environment is now global, humanity as a collective must act to self-regulate. Unfortunately, humanity is not at present a collective, and we are only beginning to construct a worldview that is consistent with living within the biophysical limits of the planet. This post examines three concepts that may help move us towards those goals.
The Technosphere
The term technosphere has been used for decades in the field of Science and Technology Studies and is loosely construed as the sum of all technological artifacts on Earth. Often it is credited with having a degree of autonomy in the sense of its growth having a direction and momentum outside of human control. The current difficulty in reducing fossil fuel related emissions of greenhouse gases is indicative of that autonomy.
In the last decade, the technosphere concept has been more formally defined as:
the set of large-scale networked technologies that underlie and make possible rapid extraction from the Earth of large quantities of free energy and subsequent power generation, long distance, nearly instantaneous communication, rapid long-distance energy and mass transport, the existence and operation of modern governmental and other bureaucracies, high-intensity industrial and manufacturing operations including regional, continental and global distribution of food and other goods, and a myriad additional ‘artificial’ or ‘non-natural’ processes without which modern civilization and its present 7 × 109 human constituents could not exist.
Earth system scientists now make quantitative estimates of the properties of the technosphere such as total mass and annual energy throughput. The juxtaposition of technosphere metrics like global fertilizer use, with biosphere metrics like global nitrogen fixation, reveals the growing dominance of the technosphere in the global biogeochemical cycles and points to the limits to technosphere growth.
The technosphere is in some ways analogous to the biosphere. Both are globe girdling aggregations of quasi-independent subsystems. In energetic terms, both the biosphere and the technosphere are dissipative structures, meaning they capture and use energy to maintain order. The biosphere changes by way of biological evolution; the technosphere changes by way of cultural evolution.
Humans and their institutions are parts of the technosphere, and human thinking is required to organize the technosphere. But the question about technosphere autonomy, and its possible danger to humanity, remains. Notably, the capitalist economic system that underlies the technosphere thrives on growth. Relentless technosphere growth is in effect consuming Earth system capital, such as biodiversity and fossil fuel, that has accumulated over millions of years. Astrobiologists, who ponder evolution of intelligent life on other planets, suggest that an environmentally self-destructive technosphere may significantly limit (filter) how often sustainable high technology planetary civilizations arise in the universe.
A critical problem with Earth’s current technosphere is that due to its rapid and recent evolution, it does not have the kind of feedback loops (as found in the biosphere) needed for self-regulation. Humans are programmed (biologically) to exploit all available resources, but we haven’t evolved culturally to understand limits. Haff emphasizes that the lack of recycling within the technosphere (with the accumulation of CO2 in the atmosphere from fossil fuel combustion as an iconic example). Life cycle analyses of all manufactured products, and better monitoring of input/recycling/output budgets (e.g., for aluminum) at the global scale is required for a sustainable technosphere.
Russian biogeochemist Vladimir Vernadsky (1863 – 1945) was one of the first scientists to explicitly study Earth as a whole. He understood that the biosphere (the sum of all living matter) added an unusual feature to the planet. The biosphere uses the energy in solar radiation to maintain a new form of order (life) on the surface of the planet. That layer of living matter is a major driver of the global biogeochemical cycling of elements such as carbon, nitrogen, and phosphorus. Vernadsky emphasized that the biosphere was a new kind of thing in the universe, i.e. a step forward in cosmic evolution.
He also recognized that humanity, as a result of the industrial revolution, had become of geological significance. Like the biosphere, humanity and its technology are a product of cosmic evolution – in this case relying upon an organism-based nervous system capable of consciousness and symbolic thinking. By extension from the existing concepts of lithosphere, hydrosphere, atmosphere and biosphere, Vernadsky adopted the term noosphere for this new layer of thinking matter that could alter the global biogeochemical cycles.
The noosphere as conceived by Vernadsky was just getting powered up in his lifetime. He defined it more as a potential transformation of the biosphere – “a reconstruction of the biosphere in the interests of freely thinking humanity as a single entity”.
Vernadsky’s noosphere concept lay mostly dormant for much of the 20th century (although see Sampson and Pitt 1999). Around the turn of the century, Nobel Prize winning atmospheric chemist Paul Crutzen evoked Vernadsky’s idea of transforming the biosphere into a noosphere. But in this 21st century usage, the issue of dangerous human meddling with the Earth system had risen to prominence and the inevitability of a stabilized noosphere was less certain. Similarly, Turner proposed that an updated meaning for noosphere would refer to a planetary system as a whole in which an intelligent life form had developed advanced technology but had learned to self-regulate so as to not degrade the planetary life support system.
In a slightly different take, noosphere is proposed as a paradigm for an era to follow the Great Acceleration. In this case, the noosphere is still imagined as emerging from the biosphere, but here in response to the threats of anthropogenic global environmental change. The maturation of the noosphere would mean the arrival of a global society that collaboratively self-regulates its impact on the Earth system.
Limitations of the Noosphere Concept
As noted, Vernadsky was writing before the scientific discovery that humanity was altering the atmosphere, e.g., by increasing the concentrations of greenhouse gases. Thus, he did not foresee humanity’s possible self-destructive tendencies. His noosphere concept was more about Promethean management of the Earth system than about humanity learning how to self-regulate, which is what we need now.
In most versions of the noosphere concept, the biosphere is “transformed” into a noosphere, hence in its fruition it would physically include the biosphere. However, the biosphere (much of it microbial) will always be capable of functioning independent of human attempts to manage the Earth system. The biosphere could be said to have agency relative to human impacts, which might be a more realistic basis on which to attempt to manage it.
Vernadsky’s noosphere was purely physical, but other users of the term have interpreted it more metaphysically, especially Teilhard de Chardin who referred to a purely spiritual endpoint of noosphere evolution. This spirituality and teleology have made the noosphere concept aversive to many scientists (see Medawar in Sampson and Pitt 1999).
The Global Brain
About the same time (1920s) that the noosphere meme was fostered by Vernadsky, Teilhard de Chardin, and Le Roy, the concept (or metaphor) of the global brain also emerged. Novelist and futurist H.G. Wells (1866 – 1946) proposed that all knowledge be catalogued in a single place and be made available to anyone on the planet. His hope was that this common knowledge base might lead to peace and rapid human progress. Given that World War II was soon to erupt at the time of his “World Brain” proposal, Wells was clearly ahead of his time.
Like the noosphere concept, the World Brain concept was not much referred to in the decades following its origin in Well’s imagination. However, the late 20th century Information Technology revolution has reinvigorated discussion about it. With rapid build out of the global telecommunications infrastructure, the global brain has begun to be envisioned as something wired together by the Internet.
Systems theorist Francis Heylighen and his collaborators at the Global Brain Institute have devoted considerable attention to building the analogy between the human brain and a proposed global brain, especially in relation to the process of thinking.
Heylighen sees the global brain as a necessary part of an emerging social superorganism – a densely networked global society. His global society will coalesce because information technology now offers a growing proportion of the global population access to a wealth of information and an efficient way to organize production and consumption of goods and services. Rather than totalitarianism, the high level of connectivity in Heylighen’s model of the social superorganism stimulates individuals to develop themselves (while still acknowledging membership in a global collective). This model leads to more distributed, less hierarchical, power centers.
How the global brain will think is not well characterized at present. Cultural evolution has always been a form of collective intelligence and the binding power of the Internet now provides a forum for a global collective to exchange ideas (memes). Changes in the frequency distribution of search term or web page usage would be one means of monitoring global thinking.
Collaborative development of the Community Earth System Model is an example of collective thinking on a limited scale. Specialist scientists work to improve the many subsystems of the model, and periodically the computer code is updated based on a consensus decision.
One other intriguing analogy relates to a characteristic feature of the human brain in which it makes frequent (conscious or unconscious) predictions. If they are not fulfilled, a motivation to act may be instigated. With Earth system model scenarios now produced in the context of climate change assessment, the global brain might also be said to be constructing scenarios/predictions for itself. Comparisons of scenarios, or detection of discrepancies between favorable scenarios and how reality is playing out, could inspire corrective action by the global collective.
Limitations of the Global Brain Concept
The analogy of global brain to individual brain is certainly a stimulant to conceptualizing new global scale structures and processes. However, since we barely understand our own consciousness and decision-making processes, it is an analogy that still needs a lot of work, especially with respect to the executive function. In the near-term, humanity needs research and models on how to integrate governance among 8-10 billion people (i.e. what form of institutions?) and how to convince billions of planetary citizens to cooperate in the effort that humanity must make to self-regulate. The global brain concept does not facilitate the coupling of the human enterprise to the rest of the Earth system.
Conclusions
The technosphere, noosphere, and global brain concepts share a common concern with understanding the relationship of the burgeoning human enterprise, including its technology, to the entirety of the Earth system. Anthropogenic global environmental change poses an existential threat to humanity and there is a clear need for a Great Transition involving massive changes in values as well as technology. These three concepts serve as beacons pointing towards global sustainability.
The utility of the technosphere concept is that it refers to measurable entities, and formally meshes with the existing Earth system science paradigm. Given that humans are only part of the technosphere, and a part does not control the whole, awareness of the technosphere argues against hubris. However, the technosphere concept doesn’t engage the host of psychological and sociological issues that must be addressed to rapidly alter the Earth system trajectory. It helps reveal the danger humanity faces but doesn’t foster a worldview that will ameliorate the danger.
The chief utility of the noosphere concept is its cosmic perspective and aspirational quality. A weakness is ambiguity about what the noosphere includes and how it operates.
The utility of the global brain concept is that it confirms we have the technical means to actualize global collective intelligence, which will be required to deal with the overwhelming complexity of the Earth system. A weakness is a limited model of global governance and a lack of attention to the rapid erosion of the human life support system (the biosphere) that must function well for the emerging global brain to flourish. The capacity of individuals to know themselves, i.e. to reflect on their own behavior and its consequences, can potentially be scaled up to the global human collective. This process will depend on the communication possibilities opened up by the Internet.
The technosphere, noosphere, and global brain concepts will contribute to synthesizing a new model of the planetary future that includes a functioning global society and a technological support system that maintains a sustainable relationship to the rest of the Earth system.
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.
The reduction in CO2 emissions in response to Covid-19. Image Credit: Global Carbon Project.
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.
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.
Figure 1. An Earth system science inspired Anthropocene narrative with six stages. Image credits below.
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.
Figure 2. The pre-human biosphere was a precondition for the biological evolution of humans. Image Credit: NASA image by Robert Simmon and Reto Stöckli.
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.
Figure 3. The story of Adam and Eve symbolizes the separation of early humans from the background natural world. Image Credit: Adam and Eve expelled from Eden by an angel with a flaming sword. Line engraving by R. Sadeler after M. de Vos, 1583. Wellcome Trust.
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.
Figure 4. The Earth at night based on satellite imagery displays the global distribution of technology dependent humans. Image Credit: NASA/GSFC/Visualization Analysis Laboratory.
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.
Figure 5. The impacts of the global human enterprise on various indicators of Earth system function take on an exponential trajectory after World War II. Image Credit: Adapted from Steffen et al. 2015.
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.
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.
Figure 7. An idealized landscape in which the biosphere and technosphere are sustainably integrated. Image Credit: Paul Cézanne, Mont Sainte-Victoire, 1882–1885, Metropolitan Museum of Art.
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)
When I was 20 years old, I picked up a paperback version of
“Life and Energy” by Isaac Asimov. This
lucid scientific description of the chemical basis for life was very
compelling, indeed, it helped inspire me to pursue a career in biology and
ecology. The time around its publication
in the mid 1960s was quite exciting in biology because the fields of
biochemistry and cell biology were in full flower; scientists had worked out
the role of DNA in regulating cellular metabolism and had achieved a good
understanding of the chemistry of photosynthesis and respiration.
Metabolism is broadly defined as the chemical machinery of
life, the networked sequences of chemical reactions that build and maintain living
matter. Biologists think of living
matter in terms of levels of organization – from cells, through
organisms, communities, and the biosphere.
In Asimov’s days, the concept of metabolism was mostly applied at the level of the cell or organism. However, ecologists in recent years have also applied it in the context of ecosystems and the Earth system as a whole. Here I would like to consider metabolism at the scale of the technosphere.
An ecosystem is a biogeochemical cycling entity, e.g. a pond
or a patch of forest. Like an organism,
it requires a source of energy and it cycles nutrients such as nitrogen from
one chemical form to another. Strictly
speaking, it is the biota (the set of all organisms) that in a sense has a
metabolism. Component organisms are
classified into nutrient cycling guilds — most simply as producers (photosynthesizes),
consumers, and decomposers.
Ecosystem metabolism can be described in terms of energy fluxes, as well as the stocks and fluxes of key chemical elements. The element carbon plays a central role in ecosystem metabolism. Its cycle extends from the atmosphere, through plants, to animals, and to decomposers, then back to the atmosphere.
The ecosystem carbon cycle. Image credit, Figure 4.1, The Green Marble, David Turner, 2018, Columbia University Press.
At the scale of the Earth system, we can likewise talk about
biogeochemical
cycling guilds and the associated biogeochemical cycles. Biosphere metabolism is based on
photosynthesis on the land and in the ocean.
Biosphere driven element fluxes help regulate the atmospheric chemistry,
ocean chemistry, and global climate.
Despite repeated intervals in the geologic record of Hothouse
Earth and Icehouse Earth, the metabolism of the biosphere has run steadily for
over 3 billion years.
Quite recently in geologic time, a new sphere has emerged within
the Earth system. This “technosphere” is
the cloak of technological devices and associated human constructs that has
come to cover the Earth. Like the biosphere,
it
has a metabolism.
We can think about technosphere metabolism in terms of three
key factors: energy flows, materials cycling, and information processing.
Humans are a part of the technosphere and mostly benefit
from its metabolism. The technosphere
produces a vast array of goods and services that support billions of
people. However, the metabolism of the technosphere
has begun to disrupt the formerly background global biogeochemical cycles. It is effectively now a geological force and
the changes it has precipitated are not necessarily favorable to advanced
technological civilization. Notably, the
delivery of vast amounts of CO2 into the atmosphere is destabilizing
the global climate. A course correction in
the evolution of the technosphere is required.
Energy flow into the technosphere is predominantly from the
combustion of fossil fuels (coal, oil, and natural gas). The problem is that the resulting source of
carbon to the atmosphere is orders of magnitude greater than the background
source from volcanoes. The background
geologic sink for CO2 by way of mineral formation in the ocean
depths is likewise small.
Some of the technosphere-generated CO2 is sequestered
by land plants and in the ocean, but most of
it is accumulating in the atmosphere and causing the planet to rapidly warm. The technosphere has begun to disrupt the
entire Earth system.
The solution, as is well known, is conversion of the global energy infrastructure to renewable energy sources (solar, wind, hydro, geothermal, biomass, and renewable natural gas). That conversion is a daunting task but technically it can be accomplished. The challenge is as much to economists and politicians as it is to engineers.
Converting from fossil fuel-based energy sources to renewable energy sources. Image credit for power plant and wind turbines.
The materials cycling factor in technosphere metabolism is problematic because the technosphere as currently configured is not effective at recycling its components. Unlike the biosphere, in which nutrients are cycled, there is often a one-way flow of key chemical elements in the technosphere − from a mineral phase, to a manufactured product, to a landfill.
The problem is that sources of the technosphere components
are not infinite. Building the next mega-mine
to extract aluminum degrades the biosphere, a key component of the global life
support system.
Again, this is a largely solvable problem using advanced
industrial practices. We now speak of
the emerging circular
economy and of dematerializing
the technosphere. More comprehensive
recycling may require more energy than dumping something into a landfill, but
the potential for renewable energy sources is large.
The information processing aspect of technosphere metabolism
refers to its regulatory framework. Regulation
requires information flow, a receiver of that information, and a mechanism to
act on it.
Homeostasis at the level of an organism is a clear case of
regulation. Homeostasis of internal
chemistry, such as the blood sugar level in mammals, depends on factors
including signals based on chemical concentrations, DNA-based algorithms to
formulate a response, and organs that implement a response.
Ecosystems also self-regulate in a sense. Disturbances (e.g. a forest fire) are
followed by vigorous regrowth. As a
result, nutrients that are released in the process of the disturbance are
captured and prevented from loss by leaching.
Damaged ecosystems, say that lack species specialized for the early
successional environment, may deteriorate after a disturbance.
At the global scale, Earth system scientists have long
debated the issue of planetary homeostasis.
James Lovelock famously hypothesized that indeed the Earth
system (Gaia) is homeostatic with respect to conditions that favor
life. His idea inspired much research,
and many significant biophysical feedbacks to global change have been
identified. The biosphere clearly exerts
a strong influence on global climate by way of its impacts on greenhouse gas concentrations,
specifically through its role as an amplifier
in the rock
weathering thermostat.
A new research question concerns the degree to which the technosphere
is homeostatic. Continued
exponential growth in many of the indices of technosphere metabolism is
suggestive of inadequate regulation. To
begin with, the regulatory capability of the technosphere is obviously diffuse
and underdeveloped.
Monitoring is a necessary component of effective management
systems but the self-monitoring capability of the technosphere barely existed
until quite recently. An anomalous
growth in the atmospheric CO2 concentration was measured in the late
1950s by atmospheric chemist Charles David Keeling. This observation was the first clear signal
of technosphere impact on the Earth system.
The Landsat series of
satellite-borne sensors that monitor land cover change, e.g. deforestation
and urbanization, was initially launched in 1972. These satellites have since tracked the explosive
spatial expansion of the technosphere. A
fleet of other satellites now monitors many other features of the global
environment.
From synthesis efforts by agencies such as the United Nations
Food and Agriculture Organization, we have good observational data on the
growth of key technosphere variables like global population size and energy use.
As far as a decision-making organ for the technosphere, one
barely exists at present. You might say
that market-based capitalism is the organizing principle of the current technosphere. Everyone wants cheap, plentiful energy (the
demand side) and the global fossil fuel industry has managed to keep ramping up
the supply. Under the current neoliberal
economic regime, the environmental costs are externalized, and no global oversight
is imposed.
However, a new constraint has arisen. The scientific community has built Earth
system models to refine our understanding of Earth’s biophysical regulatory
mechanisms and to simulate effects of various greenhouse gas concentration scenarios. These simulations make clear that uncontrolled
emissions of CO2 from fossil fuel combustion must cease or advanced technological
civilization will be imperiled. The 2015
Paris Agreement on Climate Change was a step towards reining in the technosphere,
but the influence of that international agreement is not commensurate with the
challenges of current global environmental change.
An essential feature of a needed paradigm shift regarding technosphere
regulation is the development of a global environmental governance
infrastructure. The technosphere is
having global scale impacts on the environment and must correspondingly be
evaluated and regulated at the global scale.
A proposed World
Environment Organization would not necessarily supersede the traditional nation-state-based
architecture of global governance, but it could go a long way towards the
required scale of integration needed to address global environmental change
issues.
A revamped technosphere metabolism must be built over the
course of the 21st Century in which the energy sources are
renewable, the material flows are cyclic, and the regulatory framework is rooted
in an understanding of limits. Societies
are more likely to change under extreme circumstances, and the economic shock
of the 2020 coronavirus pandemic will certainly qualify as extreme. As the global economy recovers, there will be
significant opportunities to change technosphere metabolism. Let’s hope they are not wasted.
An image of the global biosphere in
which depth of greenness on land represents annual photosynthesis. Wikimedia Commons
Natural Processes are
Slowing the Accumulation of Carbon Dioxide in the Atmosphere − Strategic Land Management Could Boost That Trend
As global climate warms in response to rising greenhouse gas
concentrations, various components of the Earth system are responding in ways that
amplify or suppress the rate of change.
Most of these feedbacks
are positive (amplify warming). However,
a natural negative feedback (suppresses warming) exists and it could be
augmented by human actions.
Scientists generally agree that an increase in the
concentration of carbon dioxide (CO2) in the atmosphere,
precipitated by human activities, is a major driver of climate change. Hence, any process induced by rising CO2
and climate change in which less CO2 is added to the atmosphere, or more
CO2 is removed from the atmosphere and sequestered, constitutes a
negative feedback to climate change.
The most obvious and necessary negative feedback is a rapid
reduction in fossil fuel emissions. The
2015 Paris Agreement on Climate Change points to progress in that direction. Unfortunately, fossil
fuel emissions continue to rise.
Research in Earth system science is examining the operation
of another significant, but naturally occurring, negative feedback to climate change. Observations suggest that the rising atmospheric
CO2 concentration and associated climate change is spurring carbon sequestration
by the terrestrial biosphere.
Earth system scientists speak of the “carbon
metabolism” of the terrestrial biosphere, referring to the uptake of carbon
by way of photosynthesis
and its release back to the atmosphere by way of respiration of plants,
animals, and microbes (Figure 1). When
photosynthesis exceeds respiration, carbon is sequestered from the atmosphere. A critical question concerns the degree to
which humanity can purposefully augment this negative feedback and help slow
climate change.
Figure 1. The
atmospheric CO2 concentration is a function of uptake by processes
such as plant photosynthesis, and release by processes such as respiration and
combustion of fossil fuels. Wikimedia
Commons.
The Terrestrial Biosphere is Speeding
Up
Laboratory and chamber studies show that plant photosynthesis is generally sped up, and drought stress is alleviated, as CO2 concentration increases. At the global scale, long-term observations are finding a trend of increasing global photosynthesis in recent decades as the CO2 concentration in the atmosphere rises. The estimated increase is on the order of 30% based on four independent lines of evidence.
The dominant reservoir for sequestered carbon is most likely
wood. Note that forests accumulate wood as they
recover from disturbances. Thus, the
terrestrial biosphere uptake or “sink” for carbon is a function of both the
disturbance history of global forests and the stimulation of wood production by
high CO2.
One indication of an invigorated biosphere comes from
observations of the atmospheric CO2 concentration at Mauna Loa Hawaii. The iconic “Keeling curve” (Figure 2) shows
an upward trend attributable mostly to fossil fuel emissions, and an annual
oscillation, which is attributable to terrestrial biosphere metabolism. The annual drawdown in concentration is
driven by an excess of photosynthesis over respiration in the northern
hemisphere spring, and observations of CO2 in recent decades find a strengthening
of that drawdown. Contributing
factors include a longer growing season, deposition of nitrogen from polluted
skies (= fertilization), and CO2 stimulation of growth.
Figure 2. Monthly mean atmospheric carbon dioxide at
Mauna Loa Observatory, Hawaii (in red).
The black curve represents the seasonally corrected data. NOAA.
Increasing
carbon sequestration by the biosphere is evident from the observation that
the proportion of human generated carbon emissions that stays in the atmosphere
(the airborne fraction) has fallen in the last decade, despite the large upward
trend in fossil fuel emissions. The
airborne fraction was 44% for the 2008-2017 period, with the remainder of
emissions accumulating on
the land (29%) or in the ocean (22%).
Human Augmentation of Terrestrial Biosphere
Carbon Sequestration
So, we have a natural brake on the rising CO2
concentration. And it is one that could
potentially be augmented by human intention.
Thus far, human land use impacts such as deforestation and
agriculture have tended to decrease biosphere carbon storage. However, there is a large potential to
deliberately sequester carbon in terrestrial ecosystems by way of several
approaches.
1. Expansion of the
UN-REDD Programme (United Nations Reducing Emissions from Deforestation and
Forest Degradation). REDD consists of intergovernmental
agreements that pay developing countries to protect forests. The carbon benefit is both in
terms of reducing carbon emissions and maintaining carbon sinks. Remote sensing is increasingly effective in monitoring
carbon stocks. Norway has begun to
make payments
to Indonesia for reducing rates of deforestation.
3. Planting trees −
something that can be done at the scale of a suburban back yard, whole urban
areas, or regions (Figure 3). Satellite-observed
greening in China is attributed in part to large scale tree planting. Trees affect the absorption and reflection of
solar radiation as well as the carbon balance, so care
must be taken about planning large scale plantings.
Figure 3. Forests accumulate
large stocks of carbon relative to other vegetation cover types. Wikimedia Commons.
These human-mediated carbon sinks will all benefit from high
CO2 impacts on biosphere metabolism.
In contrast, the impacts of continuing climate change − independent of
CO2 impacts − on these carbon sinks and on biosphere metabolism
generally are difficult to anticipate. At
high latitudes, climate warming appears to be associated with vegetation
greening. In contrast, increased
rates of disturbance in mid-latitudes − such as climate warming
induced forest fire − may offset the strength of biosphere carbon sequestration.
In an optimistic scenario, radically reduced fossil fuel emissions along with increased carbon uptake by the land and ocean will cause the atmospheric CO2 concentration to peak within this century, leading to a gradual decline that is powered by biosphere sequestration (natural and augmented).
Since we are already committed to significant climate
change, that CO2 trajectory would still leave us with major − but
hopefully manageable − adaptation challenges.
A stabilized CO2 concentration, would also reduce the
possibility that the Earth system will cascade through of series of positive feedback tipping
points.
That scenario would take hundreds to thousands of years to play out but
it could push Earth into a state threatening to even a well-organized,
high-technology, global civilization.
Gaia was originally a figure from Greek mythology: the
mother goddess who gave birth to the sky, the mountains, and the sea. Gaia was adopted by the Romans when they
conquered the Mediterranean basin, but her myth was largely abandoned with the
ascendency of Christianity by the third century CE.
The first revival of Gaia was a product of the nascent
Earth system science community in the 1970s.
Atmospheric chemist James Lovelock was impressed by the finding of geologists
that life had persisted on Earth for over 3 billion years despite a 25%
increase in the strength of solar radiation (associated with an aging sun), and
numerous catastrophic collisions with asteroids. He also understood that the chemistry of the
atmosphere − which provides oxygen for animal respiration, protection from
toxic solar UV-B radiation, and influences the global climate − was maintained
by the metabolism of the biosphere.
These observations led him to suggest that the Earth
as a whole was in a sense homeostatic, it was able to maintain certain life
enhancing properties in the face of significant perturbations.
In casting around for a name to give this organism-like version of the planet, he was inspired by author William Golding to revive the term Gaia. Lovelock and microbiologist Lynn Margulis went on to write many influential peer-reviewed papers, and later books, on Gaia.
By the 1990s, the question of what regulated the functioning
of the Earth system had become of more than academic interest. Earth system scientists had observed that the
Earth system was changing and begun to worry about possible impacts of those
changes on the human enterprise. Concentrations
of greenhouse gases were rising, stratospheric ozone was declining, and a wave
of extinctions was sweeping the planet.
Geoscientists were initially intrigued by the Gaia Hypothesis about planetary homeostasis, hoping perhaps that Gaian homeostasis might save us from ourselves. But by around 2000 they had largely rejected Gaia as an entity. Many of the feedbacks in the Earth system (see my Teleological Feedback blog) were positive (amplifying climate change) rather than negative (damping), hence not contributing to homeostasis.
The second revival of Gaia came predominantly from scholars in the humanities. Historians typically begin human history about 10,000 years ago when humans adopted an agricultural way of life. However, the discovery that humans have recently begun to alter the global environment on a geologic scale changes everything (as activist Naomi Klein says). The Earth system is no longer a benevolent background state that will provide a growing humanity with unlimited resources. Earth has a Gaian history that is now imposed upon by human history. The new field of Big History aims to juxtapose the geologic and anthropocentric time frames.
Historians needed a term to evoke an Earth system that
in a sense has its own agency, and scholars like science historian Bruno Latour
and philosopher Isabelle Stengers settled on Gaia. They emphasized Gaia not as a nurturing
mother, but rather a force that will smack humanity down if the current
trajectory of global environmental change continues.
In a recent hybrid interpretation, geoscientist Tim Lenton
and humanities scholar Bruno Latour have dubbed the newly revived Gaia as Gaia
2.0. This version refers to an Earth system on
which a sentient species has evolved and begun to alter the planet but has collectively
taken on the project of developing an advanced technological civilization (a
technosphere) that will live on the planet sustainably. That means comprehensive renewable energy, nearly
closed material cycling, conservation of biodiversity to support the background
metabolism of Gaia 1.0, implementation of multiple strategies to moderate
climate change, and forms of governance that facilitate self-regulation at
multiple scales.
Gaia 2.0 is the combination of the pre-human Gaian Earth system and the recently emergent technosphere.
