Abstract

Planetary intelligence—the capacity of a biosphere–technosphere ensemble to sense, learn, and act coherently across geological timescales—has matured into a cross-cutting research programme bridging astrobiology, complex-systems theory, cognitive science, and philosophy of science (Frank & Sullivan, 2022; Lingam & Frank, 2023). Building on my recent call to move beyond conventional boundaries (Milanese, 2024, 2025), I integrate the latest empirical and theoretical work to (a) characterise the cognitive and computational properties of Earth’s biosphere, including new order-of-magnitude estimates of planetary information throughput; (b) analyse the reciprocal coupling between human cognition, the expanding technosphere, and biospheric regulation; (c) evaluate methodological obstacles—data sparsity, deep-time inference, observer entanglement—and propose falsifiable active-inference and network-thermodynamic metrics; and (d) re-frame the Search for Extraterrestrial Intelligence (SETI) around planet-level technosignatures and Exo-Gaia diagnostics.

I argue that self-organised criticality, anticipatory homeorhetic control, and multiplex information channels render the Earth system a form of distributed cognition whose substrate spans biogeochemical, climatic, and technological layers. Quantifying this cognition—now estimated at ~10²⁴ bits s⁻¹ of biospheric processing plus ~10¹⁵ bits s⁻¹ of human digital traffic—transforms planetary stewardship from resource management to an alignment problem: ensuring that sub-agent goals (humans, corporations, artificial intelligences) remain congruent with the long-term free-energy minimisation of the planet itself. Recognising humanity as both participant in and perturbation to Earth’s emergent mind foregrounds policy, ethics, and machine-learning design choices as levers for sustaining planetary habitability and for guiding future SETI efforts toward worlds where cognition is written across an entire planet.

Introduction

Background and Rationale

Over the past half-century, the guiding inquiry has evolved from "Is Earth alive?" (Lovelock & Margulis, 1974) to "Is Earth thinking?" (Frank & Sullivan, 2022). Breakthroughs in Earth-system modelling, network neuroscience, and basal-cognition research now demonstrate that life can perform computation at scales far exceeding a single organism (Fields et al., 2023). In my earlier work, I argued that intelligence is a scale-invariant, emergent property of self-organising processes—extending from molecules to minds to planets (Milanese, 2025)—and urged scholars to traverse disciplinary membranes when probing consciousness, cosmos, and complexity (Milanese, 2024). Planetary intelligence is here defined as the acquisition, retention, and goal-oriented deployment of knowledge by an integrated life–environment–technology complex operating at global scale and coupled to geophysical boundary conditions over geological time (adapted from Frank et al., 2022). This formulation treats Earth's biosphere, climate machinery, and expanding technosphere as a single, recursively self-modelling information processor—analogous in function, though not in substrate, to a neural architecture—and frames intelligence as a thermodynamically constrained strategy for long-term habitability. Building on that foundation, this chapter asks: What does it mean to treat Earth's biosphere as an intelligent, computational entity, and how might that perspective reshape our understanding of cognition, evolution, and technocultural futures?

Key Questions

Computational biosphere. What information-processing operations are realised by coupled biogeochemical cycles, trophic webs, and climatic feedbacks?
Human–planet coupling. In what sense is human cognition a sub-routine—and occasionally a perturbation—within a larger planetary computation, and how does the technosphere modulate that coupling?
Epistemic and methodological limits. How can we investigate cognition without neurons at planetary scale, given data sparsity, deep time, and observer entanglement?
SETI and exocognition. If intelligence is fundamentally planetary, how should we recalibrate our search strategies for life and mind beyond Earth?

Structure of the Chapter

Figure 1 (conceptual map to follow) traces the argument’s flow—from foundational theory, through empirical evidence, to speculative horizons—and each major section concludes with explicit, testable hypotheses or falsification protocols.

planetary intelligence illustration – glowing planet with concentric data rings and moonlets showing global feedback loops — **Planetary Intelligence in Motion** – A luminous core encircled by data-like rings illustrates how a biosphere-technosphere ensemble senses, learns and acts over deep time.

Planetary Intelligence: Detailed Outline

1. Conceptual Foundations

Purpose: Establish the theoretical groundwork for understanding intelligence as a planetary-scale phenomenon

1.1 From Gaia to Noosphere: Historical Lineage

Vernadsky's Vision (1926): The biosphere as geological force; prophetic concept of the noosphere
Lovelock-Margulis Revolution (1974): Gaia hypothesis - Earth as self-regulating cybernetic system
Frank's Synthesis (2022): Planetary intelligence as measurable information-processing capacity
Historical Sidebar: Tracing the evolution from biospheric regulation to cognitive planet

1.2 Defining Planetary Intelligence [Box 1]

Core Definition: Collective knowledge and cognition of planet-scale life-environment-technology complex
Three Pillars:
- Substrate plurality (biotic, abiotic, technospheric components)
- Anticipatory dynamics (homeorhetic trajectories, not homeostasis)
- Emergent networked interaction (no central control locus)
Thermodynamic Framework: Intelligence as strategy for maintaining far-from-equilibrium states

1.3 Biospheric Computation: Theoretical Constructs

Information Channels: Biochemical, atmospheric, oceanic, technospheric networks
Computational Architecture: Massively parallel, fault-tolerant, asynchronous processing
Downward Causation: How planetary-scale patterns constrain local dynamics
Quantitative Baseline: Earth's information throughput ≈ 1.3 × 10²⁴ bits s⁻¹

2. Cognitive & Computational Properties of the Biosphere

Purpose: Demonstrate empirical evidence for Earth's distributed cognitive capabilities

2.1 Self-Organization and Criticality

2.1.1 Bridging Scales: From ant colonies to planetary networks - the emergence of intelligence through interaction patterns
2.1.2 Micro to Macro: Autocatalytic loops to atmospheric jet streams (7 orders of magnitude)
2.1.3 Climate-Biosphere Coupling: Network analysis revealing critical transitions
2.1.4 Information-Theoretic Perspective: Peak mutual information at criticality
Box 2: Worked Example - SOC forest fire information dynamics

2.2 Homeorhesis and Anticipatory Regulation

2.2.1 Beyond Homeostasis: Systems returning to trajectories, not set-points
2.2.2 Predictive Control: Active inference and Markov blanket models
2.2.3 Empirical Signals: Solar cycle correlations, vegetation pre-adaptation
2.2.4 Bayesian Biosphere: Earth "predicting" through embodied models

2.3 Multiscale Information Flows

2.3.1 Four Information Channels: Biochemical, genetic, physical, technospheric
2.3.2 Teleconnections as Synapses: Atmospheric patterns as planetary "axons"
2.3.3 Technosphere Integration: Digital networks adding 3 × 10¹⁵ bits s⁻¹
2.3.4 Network Neuroscience Parallels: Convergent motifs across scales

2.4 Measuring Planetary Information Throughput

2.4.1 Quantitative Baselines: Updated calculations from photosynthetic electron transfer
2.4.2 Information Diversity: Shannon entropy across genomic/metabolomic/techno realms
2.4.3 Empirical Toolkits: Biospheremetrics package, satellite missions
2.4.4 Planetary Connectome: Mapping Earth's information architecture

3. Human Cognition and Planetary Intelligence

Purpose: Analyze humanity's role as both component and perturbation in Earth's cognitive system

3.1 Distributed Cognition Framework

Hutchins-Clark Foundation: Cognition beyond individual brains
Planetary Application: Earth as vast distributed cognitive system
Unconscious Coordination: Carbon cycle as distributed computation
Table: Empirical proxies for planetary cognitive functions

3.2 Parallels and Divergences

Shared Properties: Information integration, memory, prediction
Scale Differences: Temporal (milliseconds vs millennia), spatial (meters vs megameters)
Substrate Distinctions: Neurons vs ecosystems, synapses vs teleconnections

3.3 Technosphere as Emergent Neural Layer

Digital Acceleration: Exponential growth in information processing
Feedback Intensification: Real-time planetary monitoring and response
Risk Factors: Potential for destabilizing oscillations

3.4 Reciprocal Feedbacks and Co-evolution

Human-Planet Coupling: Anthropocene as cognitive phase transition
Emergent Properties: Collective behaviors not predictable from components
Alignment Challenge: Sub-agent goals vs planetary stability

4. Methodological & Theoretical Challenges

Purpose: Address epistemic and practical obstacles to studying planetary-scale cognition

4.1 Scale, Sparsity, and Deep Time

Observer Entanglement: We study the system from within
Reflexivity Paragraph: How observation changes the observed
Data Challenges: Geological timescales, incomplete records
Uncertainty Quantification: Explicit error propagation

4.2 Modeling Frameworks

4.2.1 Active-Inference Earth: Free energy minimization at planetary scale
4.2.2 Agent-Based Models: Bottom-up emergence from heterogeneous actors
4.2.3 Digital Twin Approaches: High-fidelity Earth system replicas
Figure: Decision flowchart for model selection

4.3 Interdisciplinarity and Epistemic Humility

Cross-Disciplinary Integration: Astrobiology, complexity, cognition, ethics
Category Errors: Avoiding metaphor reification
Communication Barriers: Jargon, silos, prestige hierarchies
Ethical Dimensions: Responsibility of observer-participants

5. Speculative Implications for SETI

Purpose: Reframe the search for extraterrestrial intelligence through planetary cognition lens

5.1 From Radio Beacons to Planetary Diagnostics

Paradigm Shift: Intelligence as system-wide phenomenon
Technosignature Taxonomy: Atmospheric, energetic, orbital, informational
Detection Evolution: Classical SETI to planet-level signatures

5.2 Planetary Intelligence as Detection Framework

Habitability as Cognition: Long-term stability implies feedback
Exo-Gaia Index (EGI): Quantifying planetary self-regulation
Table: Stage taxonomy - biosphere to technosphere evolution
Target Prioritization: Beyond habitable zone to cognitive indicators

5.3 Multi-channel Observational Strategy

5.3.1 Spectroscopy: JWST/HWO atmospheric analysis
5.3.2 Photometry: Machine learning for megastructure detection
5.3.3 Radio Arrays: Cross-band mutual information
5.3.4 Earth Analog: What would Earth look like from afar?
Box 3: Observational feasibility calculations

5.4 Re-framing the Drake Equation

Information-Centric Formulation: Plife and Ptech as coupled probabilities
Monte Carlo Updates: 10-100 cognitive worlds within 100 pc
Persistence Dominance: Longevity as key uncertainty

5.5 Ethical and Epistemic Considerations

Gaian Precautionary Principle: Treating planets as potential minds
Post-Detection Protocols: Systems-level risk assessment
Value Frameworks: Recognizing distributed intelligence

Synthesis Box: Convergent Evidence for Planetary Intelligence

Purpose: Crystallize how multiple evidence streams support the central thesis

6. Synthesis & Future Directions

Purpose: Transform insights into actionable frameworks for planetary stewardship

6.1 Planetary Stewardship as Alignment Problem

Core Challenge: Aligning sub-agent goals with planetary stability
Earth-Alignment Principle: Embedding boundaries in AI loss functions
Code Implementation: Planetary-aware machine learning
Digital Twin Governance: Real-time planetary dashboards

6.2 Research Roadmap 2027-2035

Milestones Table: Planet Connectome, Gaian-Exoplanet Programme, etc.
Institutional Development: Technosphere science curriculum
Measurement Infrastructure: Global Planetary Stewardship Index

6.3 Scenario Space to 2100

Enhanced Table with KPIs: Quantified triggers for each trajectory
Four Pathways: Symbiotic Integration, Pathological Synchrony, Deep Re-modulation, Cosmic Reflection
Monitoring Framework: Real-time indicators and decision points
Probability Updates: Bayesian trajectory assessment

6.4 Open Research Frontiers

Grand Challenges: Information variance, learning rates, legal frameworks
Funding Opportunities: ERC Synergy, NSF EarthCube, Horizon Europe
Next-Generation Questions: Post-biological intelligence, quantum cognition

self-organised criticality concept art – ringed planet emitting particle jets symbolising distributed computation — **Self-Organised Criticality** – A ringed world radiating streams of particles captures Earth-scale networks operating at the edge of order and chaos to maximise information throughput.

Section 1: Conceptual Foundations

Signpost: This section traces the historical lineage from Gaia to noosphere, establishes our working definition of planetary intelligence, and introduces the theoretical framework of biospheric computation that grounds all subsequent analysis.

1.1 From Gaia to Noosphere

James Lovelock and Lynn Margulis (1974) first proposed the Gaia hypothesis, arguing that life regulates planetary conditions to sustain long-term habitability. A generation earlier—but little noticed in the West—Vladimir Vernadsky ([1926] 1997) had introduced the noosphere, a reflective, knowledge-bearing layer supervening on the biosphere. Contemporary work fuses Gaia’s self-regulating cybernetics with noospheric cognition, casting planetary intelligence as the emergent capacity of a living planet to sense, process, and act on information so as to remain far from thermodynamic equilibrium (Frank et al., 2022).

Historical Sidebar: From Biosphere to Noosphere to Planetary Intelligence

The conceptual lineage of planetary intelligence traces through three pivotal thinkers across a century. Vladimir Vernadsky (1863-1945), the Russian biogeochemist, first articulated the biosphere as a geological force and prophesied the emergence of the noosphere—a sphere of human thought transforming Earth ([1926] 1997). His vision preceded cybernetics but anticipated feedback systems: "The biosphere is as much, if not more, the creation of the Sun as it is a manifestation of Earth processes."

James Lovelock, with microbiologist Lynn Margulis, revolutionized this thinking through the Gaia hypothesis (1974), proposing Earth as a self-regulating system maintaining conditions suitable for life. Unlike Vernadsky's directional evolution toward consciousness, Gaia emphasized homeostatic feedback—the planet as a cybernetic system, though not necessarily possessing purpose or awareness.

Adam Frank and colleagues (2022) synthesized these streams, introducing planetary intelligence as an empirical framework. They classify planetary evolution through stages: immature biosphere → mature biosphere → immature technosphere → mature technosphere. This progression frames intelligence not as metaphor but as measurable information processing capacity, bridging Vernadsky's teleological vision with Lovelock's mechanistic insights. Where Vernadsky saw destiny and Lovelock saw stability, Frank sees phase transitions in planetary information architecture—each building toward today's urgent question: can Earth's technosphere mature before destabilizing its biospheric foundation?

This synthesis reframes Earth not merely as a self-maintaining organism but as a learning system whose computational substrate spans lithosphere, hydrosphere, biosphere, and technosphere.

Box 1: Definition of Planetary Intelligence

Planetary intelligence is defined as the collective knowledge and cognition of a planet-scale assemblage of life and its technological progeny, enabling adaptive feedbacks that increase the probability of long-term habitability (Frank & Sullivan, 2022). This encompasses the acquisition, retention, and goal-oriented deployment of information by an integrated biosphere–technosphere complex operating at global scale and coupled to geophysical boundary conditions over geological time (adapted from Frank et al., 2022; Milanese, 2025).

Three key features characterize planetary intelligence:

1) Substrate plurality — Information processing is distributed across biotic, abiotic, and technospheric components

2) Anticipatory dynamics — The system pursues homeorhetic trajectories preserving habitable boundary conditions, rather than static homeostasis

3) Emergent networked interaction — Intelligence arises from multiscale coupling and feedback, with no single controlling locus

This formulation treats Earth's biosphere, climate machinery, and expanding technosphere as a single, recursively self-modeling information processor—analogous in function, though not in substrate, to a neural architecture—and frames intelligence as a thermodynamically constrained strategy for long-term habitability.

1.2 Defining Planetary Intelligence

Adapting Frank and Sullivan’s (2022) formulation, I define planetary intelligence as the collective knowledge and cognition of a planet-scale assemblage of life and its technological progeny, enabling adaptive feedbacks that increase the probability of long-term habitability. This definition accords with my earlier thesis that intelligence is a scale-invariant emergent property of complex adaptive systems (Milanese, 2025).

1.3 Biospheric Computation

The biospheric-computation hypothesis holds that metabolic networks, nutrient cycles, and climatic feedbacks implement operations formally mappable to computation (Walker, Davies, & Frank, 2018). Updated remote-sensing and electron-transport data place Earth’s present information throughput at ≈ 1.3 × 10²⁴ bits s⁻¹, dominated by photosynthetic electron transfers, with an additional ≈ 10¹⁵ bits s⁻¹ carried by human digital traffic (Lingam & Frank, 2023). Key information channels include

biochemical signalling—e.g., quorum sensing and root-exudate networks;
atmospheric and oceanic teleconnections—El Niño/La Niña, the North Atlantic Oscillation;
technospheric networks—fibre-optic cables, power grids, and satellite constellations.

Together these channels form a distributed, asynchronous, fault-tolerant architecture more akin to a massively parallel neural network than to a von Neumann machine (Fields, Levin, & Müller, 2023). Quantifying and modelling this architecture is the starting point for treating Earth’s biosphere–technosphere ensemble as an authentic cognitive system.

Downward Causation in Planetary Systems

Central to planetary intelligence is the concept of downward causation—the capacity for emergent, higher-level properties to constrain and guide lower-level dynamics (Ellis, 2016). In Earth's biosphere, this manifests through multiple scales of feedback. Global climate patterns constrain regional ecosystem development: the Amazon rainforest, for instance, cannot be understood solely through local soil-plant-atmosphere interactions but requires recognition of how continental-scale precipitation recycling creates and maintains the very conditions enabling tropical forest persistence (Boers et al., 2017). Similarly, the planetary carbon cycle exerts top-down control on microbial metabolic evolution—the Great Oxidation Event fundamentally altered which biochemical pathways could persist, demonstrating how biosphere-level states determine the viability space for molecular processes (Lyons et al., 2014). This bidirectional causation distinguishes complex adaptive systems from simple aggregates: while bottom-up emergence creates planetary properties, these properties subsequently shape the evolutionary and behavioral landscape of their components. For planetary intelligence, downward causation implies that once global information-processing networks emerge—whether through biogeochemical cycles or technological infrastructure—they begin to influence the trajectories of subsystems in ways that cannot be predicted from local interactions alone, potentially steering the entire system toward self-maintaining attractors.

anticipatory regulation visual – ring-bound planet with moons portraying predictive planetary feedback — **Anticipatory Regulation** – Nested moons and tightly wound rings depict homeorhetic trajectories that keep planetary systems on life-supporting paths despite constant perturbations.

Section 2: Cognitive and Computational Properties of the Biosphere

Signpost: This section demonstrates how Earth's biosphere exhibits key properties of distributed cognition—self-organized criticality, anticipatory regulation, and multiplex information flows—providing empirical support for the planetary intelligence hypothesis with quantitative estimates of global information throughput.

2.1 Self-Organisation and Criticality

Bridging Scales: From Colonies to Planets

The leap from recognizing intelligence in ant colonies or neural networks to claiming planetary-scale cognition requires careful theoretical scaffolding. Consider the scaling progression: a single ant follows simple chemical gradients, yet a colony of millions solves complex optimization problems—finding shortest paths, allocating workers, and adapting to environmental changes (Gordon, 2010). Similarly, individual neurons merely integrate and fire, but billions connected in specific architectures generate consciousness. The critical insight is that intelligence emerges not from the components but from their pattern of interactions at sufficient scale and complexity.

A planet presents the ultimate test of this principle. Earth's "components" span from soil microbes to human cities, connected through atmospheric circulation, hydrological cycles, biogeochemical fluxes, and increasingly, technological networks. These connections exhibit the same hallmarks seen in recognized intelligent systems: massive parallelism (every organism simultaneously processes environmental information), redundant pathways (multiple routes for energy and information flow), and adaptive reorganization (ecosystems shifting in response to perturbations). The question is not whether these planetary networks could generate intelligence, but whether they exhibit the requisite integration—do regional processes influence each other strongly enough to generate unified, system-wide behaviors? Evidence from global teleconnections, synchronized ecosystem responses to climate signals, and emerging technospheric coordination suggests that Earth has crossed this threshold, transforming from a collection of local systems into an integrated information-processing architecture operating at planetary scale.

2.1.1 From micro-scale autocatalysis to macro-scale avalanches

Self-organisation is the spontaneous emergence of ordered structure from initially disordered components in systems driven far from thermodynamic equilibrium (Kauffman, 2023). Within Earth’s biosphere, such dissipative structures span seven orders of magnitude—from autocatalytic metabolic loops and bacterial biofilms to atmospheric jet streams. Event-size distributions for earthquakes, wild-fires, plankton blooms, and drainage networks all follow power laws, indicating scale invariance and clustering near the critical point of self-organised criticality (SOC) (Hergarten, 2024). Two computationally salient capacities follow: (i) maximal dynamic range, enabling sensitivity to weak perturbations without saturation under strong ones, and (ii) near-optimal information transmission, as demonstrated for neural networks poised at phase transitions (Mora & Bialek, 2011).

2.1.2 Criticality in climate–biosphere coupling

Network-theoretic reconstructions of daily global air-temperature fields (1949–2019) reveal increased modularity and node isolation under anthropogenic warming, signalling incipient critical thresholds in climatic subsystems (Lee et al., 2024). Complementary early-warning analyses show that teleconnection patterns reorganise abruptly when variance and autocorrelation exceed universal critical values (Gualdi et al., 2025). Because terrestrial ecosystems entrain to these teleconnections—e.g., El Niño and the North Atlantic Oscillation—biological fluxes of carbon and water also exhibit critical cascades, implying that the coupled climate–biosphere complex functions as an SOC processor.

2.1.3 Information-theoretic perspective

At criticality, mutual information between system components peaks, maximising computational capacity. Updated order-of-magnitude models place biospheric information transmission—dominated by photosynthetic electron-transfer events—near 10²⁴ bits s⁻¹, roughly nine orders above present human digital traffic (Lingam, Frank, & Balbi, 2023). Such scaling laws portray Earth’s “living skin” as an ultrascaled neural network that maintains high sensitivity while avoiding runaway instability.

Box 2: Worked Example — Entropy Production vs Information Throughput in SOC Forest-Fire Cascade

Consider a model forest grid (1000 × 1000 cells) at self-organized criticality, where tree growth and fire spread balance. Each cell can be empty (0), tree (1), or burning (2). At each timestep:

• Empty cells grow trees with probability p = 0.01

• Lightning strikes random cells with probability f = 0.001

• Fire spreads to adjacent trees with probability 1.0

Entropy Production Calculation:

• Initial state entropy: S₀ = -Σp_iln(p_i) = 0.46 (for 60% trees, 40% empty)

• After 1000-tree fire: S₁ = 0.52 (more disorder)

• Entropy production rate: ΔS/Δt ≈ 10⁻⁴ bits/cell/timestep

Information Throughput Analysis:

Fire cascades carry information about forest connectivity:

• Small fires (< 10 trees): Low information (~1 bit) about local density

• Power-law distributed fires: I(size) ∝ log₂(size)

• Critical-size fire (≈ 10³ trees): ~10 bits about mesoscale structure

• System-spanning fire (≈ 10⁵ trees): ~17 bits about global connectivity

Key Insight:

At SOC, the system maximizes its "dynamic range"—responding to perturbations across all scales. Information throughput peaks because:

1. Signal propagation is neither damped (subcritical) nor explosive (supercritical)

2. Correlation length diverges, enabling long-range information transfer

3. Power-law distribution ensures all scales contribute to information processing

Biospheric Analogy:

Earth's ecosystems, operating near criticality, similarly process information across scales—from local nutrient pulses to continental climate shifts. A volcanic eruption (like lightning) triggers cascading responses whose extent encodes information about global system connectivity. This multi-scale information processing, characteristic of SOC systems, provides the computational substrate for planetary intelligence.

2.2 Homeorhesis and Anticipatory Regulation

2.2.1 Homeostasis versus homeorhesis

Classical ecology emphasised homeostasis: negative-feedback loops that hold state variables near fixed set-points (Cannon, 1929). By contrast, Waddington (1957) introduced homeorhesis (“similar flow”) to describe systems that return to a trajectory rather than a point. Gaia theory adopts this view, noting that atmospheric composition drifts over geological time yet remains confined to life-compatible pathways (Margulis & Lovelock, 1974). Biospheric control is thus directional regulation, not static equilibration.

2.2.2 Predictive and anticipatory control

Empirical physiology recognises predictive homeostasis: organisms adjust internal states in advance of expected perturbations (Moore-Ede, 1986). At planetary scale, seasonal modulation of oceanic primary productivity similarly anticipates insolation cycles. Active-inference formalism frames this behaviour in Bayesian terms: adaptive systems minimise variational free energy under a Markov blanket separating internal from external states (Friston, 2013). Applied to climate–biosphere coupling, Markov-blanket models reproduce emergent stability regimes without invoking teleology (Watson et al., 2020). In essence, the biosphere “predicts” its future by embodying generative models of its own dynamics.

2.2.3 Empirical signals of anticipation

Multi-decadal data link the 11-year solar cycle to reorganisation of tropospheric circulation one to two years before extreme events (Huth & Stryhal, 2024). Vegetation indices and sun-induced fluorescence display corresponding lead–lag patterns, suggesting that plant canopies pre-align photosynthetic machinery ahead of anticipated irradiance shifts (Gómez-González et al., 2024). Such feed-forward calibration places biological and climatic subsystems within a single anticipatory loop—a prerequisite for true planetary-scale cognition.

2.3 Multiscale Information Flows

2.3.1 Channels of biospheric communication

Information circulates through four principal media: (a) biochemical signalling (quorum sensing, mycorrhizal networks), (b) genetic messaging via horizontal gene transfer and viral exchange, (c) physical fluxes in riverine, atmospheric, and cryospheric systems, and (d) technospheric media such as fibre-optic cables and satellite constellations. Heterogeneity across bandwidth, latency, and spatial reach enlarges the system’s state space, enhancing creative adaptive potential (Fields & Levin, 2023).

2.3.2 Teleconnections as long-distance synapses

Atmospheric teleconnections—e.g., the Pacific–North American pattern—function as the planet’s axons, dispatching coherent wave trains that reorganise regional climates. High-resolution modelling of the 2023–24 El Niño shows that background sea-surface-temperature trends can invert canonical teleconnection signs, mirroring context-sensitive signalling in cortical circuits (Deser et al., 2025). Thus, planetary intelligence is mechanistic, not metaphorical: neurons are replaced by coupled fluid and ecological circuits.

2.3.3 Technosphere information throughput

The global technosphere currently processes on the order of (1–2) × 10¹⁵ bits s⁻¹, based on Cisco's 2023 forecast of ~1.2 × 10³ Tb s⁻¹ aggregate IP backbone capacity and TeleGeography's 2023 audit of 1,217 Tb s⁻¹ of international bandwidth (Cisco, 2020; TeleGeography, 2023). Although this is nine orders of magnitude below the heuristic biospheric communication flux (~10²⁴ bits s⁻¹), it is increasing at a compound rate of ~20 % yr⁻¹ and could overtake biospheric throughput in < century-scale scenarios (Lingam & Frank, 2023).

2.3.4 Network-neuroscience analogues

Comparative connectomics detects convergent motifs—small-world topology, modular–hierarchical layout, rich-club hubs—in brains, power grids, and climate networks (West et al., 2024). Recent analyses show that climate-network modularity increases under anthropogenic forcing, analogous to the seizure-like synchrony of epileptic brains, suggesting Earth may be approaching pathological attractors. Recognising such network pathologies enables neuro-modulation-style interventions, e.g., deliberate albedo modification as a targeted “stimulation pulse.”

2.4 Measuring Planetary Information Throughput

2.4.1  Global gross primary productivity (GPP)

Updated chemosynthetic‑pathway compilations leave the canonical global GPP at ~140 Pg C yr⁻¹ (Field et al., 1998; Ma et al., 2024).
Uncertainties in optical‑saturation corrections and emerging float‑based estimates could raise this figure by up to ~30 %, but no peer‑reviewed consensus revision has yet been published (Field et al., 2024).

Box GPP-1 Carbon-flux back-of-the-envelope

GPP [mol e⁻ s⁻¹] = 140 Pg C yr⁻¹ 12 g mol⁻¹ × 10⁶ 3.15 × 10⁷ × 10

Assumes 10 electrons transferred per CO₂ fixed in the Calvin–Benson cycle (upper-range factor to avoid undercount; Walker, 1995; Schulze & Caldwell, 1995) link.springer.com

2.4.2 Information-diversity metrics

An “information-based view” of the biosphere applies Shannon entropy to genomes, metabolomes, and technodata, revealing near-parity between prokaryotic and eukaryotic reservoirs (Walker et al., 2024). Complexity therefore resides in network architecture, not merely in node-level storage.

2.4.3 Toolkits for empirical quantification

The biospheremetrics R package automates biosphere-integrity indices by integrating trophic, climatic, and anthropogenic layers (Hijmans et al., 2024). Coupled with ESA’s FLEX fluorescence mission and NASA’s open DAAC archives, researchers can now map spatiotemporal information flux at kilometre resolution, enabling tests of SOC-based scaling laws.

2.4.4 Toward a planetary “connectome”

Prototype Planet Connectome graphs fuse ENSO indices, satellite chlorophyll, and submarine-cable traffic, identifying the Atlantic Meridional Overturning Circulation as a rich-club hub—paralleling the brainstem’s pivotal role in neural networks. Establishing such baselines will allow “surgical” interventions to protect critical planetary circuitry.

2.5 Synthesis of Section 2

Critical-state operation. The biosphere–climate composite self-organises at the edge of order and chaos, maximising perceptual acuity and computational power.
Anticipatory control. Homeorhetic trajectories, not static equilibria, steer planetary dynamics; anticipatory regulation underwrites long-term habitability.
Multiplex information channels. Biochemical, climatic, and technospheric circuits interpenetrate to form a planetary neural-like network.
Quantifiable throughput. Emerging remote-sensing and information-theoretic toolkits now permit empirical estimation of planetary bit flows and network motifs, making hypotheses about planetary intelligence falsifiable.

These findings prepare the ground for Section 3, where I examine how human cognition and culture couple into—and potentially destabilise—the planet-scale computation just described.

planetary connectome graphic – ringed planet with circuit patterns implying biosphere-technosphere coupling — **The Planetary Connectome** – Geometric overlays around a Saturn-like sphere evoke the emerging “connectome” of biochemical, climatic and digital channels that integrate Earth’s cognition.

Section 3: Human Cognition and Planetary Intelligence

Signpost: This section examines how human minds and the technosphere function as both participants in and perturbations to Earth's emergent cognition, analyzing the reciprocal feedbacks that could either enhance or destabilize planetary-scale intelligence.

Section glossary: SOC = self-organised criticality (first introduced here).

Distributed Cognition at Planetary Scale

The framework of distributed cognition, pioneered by Edwin Hutchins (1995) in his studies of navigation teams and extended by Andy Clark and David Chalmers (1998) through the "extended mind" thesis, provides crucial scaffolding for understanding planetary intelligence. Rather than locating cognition solely within individual brains, this perspective recognizes cognitive processes as emerging from the dynamic interaction of agents, tools, and environmental structures.

Hutchins demonstrated how a naval navigation team functions as a single cognitive system. No individual possesses complete navigational knowledge; instead, cognition emerges through the coordinated interaction of crew members, instruments, charts, and protocols. The ship's position—the cognitive "output"—cannot be reduced to any individual's mental state but arises from the system's integrated operation. Similarly, Clark and Chalmers argued that cognitive processes extend beyond biological boundaries when external resources become so deeply integrated with neural processes that removing them would be functionally equivalent to removing part of the brain itself.

Applying this framework to planetary scale reveals Earth's biosphere-technosphere complex as a vast distributed cognitive system. Consider how global climate knowledge emerges: no single scientist comprehends Earth's complete climate state, yet the integrated network of weather stations, satellites, computational models, research teams, and communication infrastructure generates and maintains this knowledge. The system "remembers" through ice cores and sediments, "perceives" through sensor networks, and "predicts" through coupled model ensembles.

Crucially, distributed cognition does not require conscious awareness. Just as most neural processing occurs below consciousness, planetary intelligence may operate through unconscious but coordinated processes. The carbon cycle "computes" appropriate atmospheric CO₂ levels through the distributed actions of photosynthesizers, decomposers, and geological processes—no single component "knows" the target, yet the system maintains remarkably stable conditions over geological time. The emergence of human technology adds a self-aware layer to this distributed processing, potentially enabling deliberate planetary-scale cognition for the first time in Earth's history.

Table: Empirical Proxies for Planetary Cognitive Functions

Cognitive Function	Planetary-Scale Proxy	Measurement Method	Temporal Resolution	Spatial Coverage
Short-term Memory	Atmospheric composition	NOAA flask networks, OCO-2 satellite	Minutes to days	Global, 1-10 km
	Ocean mixed-layer properties	Argo float array	Days to months	Global ocean, 2° grid
	Soil moisture	SMAP satellite	2-3 days	Global land, 9 km
Long-term Memory	Ice core records	Isotope analysis, gas chromatography	Annual to millennial	Polar regions
	Sedimentary DNA archives	Metagenomics sequencing	Decadal to millennial	Lake/ocean sites
	Tree ring networks	Dendrochronology	Annual	Continental
Perception	Satellite Earth observation	MODIS, Landsat, Sentinel	Daily to monthly	Global, 10m-1km
	Seismic networks	Global Seismographic Network	Continuous	2000+ stations
	Atmospheric radiation	CERES, GOES IR sensors	Hourly	Global
Internal State	Global mean temperature	HadCRUT5, GISTEMP	Monthly	Global
	Ecosystem productivity	MODIS GPP/NPP products	8-day composites	Global, 500m
	Ocean circulation	RAPID array, altimetry	Daily to annual	Basin-scale
Prediction/Anticipation	ENSO precursors	TAO/TRITON buoy array	Daily	Tropical Pacific
	Vegetation phenology shifts	MODIS EVI/NDVI	16-day	Global
	Seasonal carbon flux anomalies	CarbonTracker inverse model	Monthly	Global
Communication	Atmospheric teleconnections	EOF analysis of pressure fields	Daily	Global
	Ocean-atmosphere coupling	Cross-correlation analysis	Monthly	Global
	Mycorrhizal networks	Isotope tracers, DNA barcoding	Growing season	Forest plots
Learning/Adaptation	Evolutionary rates	Environmental DNA time series	Generational	Ecosystem-specific
	Ecosystem regime shifts	Multivariate state indicators	Annual to decadal	Regional
	Technological adoption curves	Infrastructure databases	Annual	Global

Note: These proxies enable quantitative assessment of planetary cognitive functions. Integration across multiple proxies strengthens inference—for example, coordinated shifts in vegetation phenology, carbon fluxes, and atmospheric composition may indicate anticipatory responses to climate forcing, suggesting planet-scale predictive processing.

3.1 Self-Organisation and Criticality

Earth systems—from autocatalytic metabolic loops to atmospheric jet streams—exhibit power-law statistics consistent with SOC, the regime in which a driven, far-from-equilibrium system organises itself to a critical threshold (Hergarten, 2024). Operating at SOC grants two computational advantages: maximal dynamic range and near-optimal information throughput. In neural tissue, those benefits manifest as avalanche dynamics that amplify weak signals without saturation (Mora & Bialek, 2011); in the biosphere, analogous distributions appear in wildfire sizes, plankton blooms, and drainage-basin areas, implying that Earth’s “living skin” is tuned for sensitive yet stable information transfer.

3.2 Homeorhesis and Anticipatory Regulation

Homeorhesis—Waddington’s (1957) term for systems that return to a trajectory rather than a fixed set-point—better captures biospheric control than classical homeostasis. Active-inference models formalise this behaviour: the coupled climate–biosphere network minimises variational free energy, thereby enacting predictive regulation without presupposing teleology (Friston, 2013; Watson et al., 2020). Empirical signals of this anticipatory regime include solar-cycle lead–lag correlations in tropospheric circulation (Huth & Stryhal, 2024) and vegetation fluorescence that adjusts months ahead of irradiance peaks (Gómez-González et al., 2024).

3.3 Multiscale Information Flows

Information moves through four partially overlapping media:

Biochemical (quorum sensing, mycorrhizal networks),
Genetic (horizontal gene transfer, viral exchange),
Physical (riverine, atmospheric, cryospheric fluxes), and
Technospheric (fibre-optic cables, satellite constellations).

Integration across these channels produces a multiplex network with small-world architecture and rich-club hubs (West et al., 2024). Atmospheric teleconnections act as long-distance synapses, and the technosphere now relays ≈ 3 × 10¹⁵ bits s⁻¹, expanding ~20 % yr⁻¹ (Cisco, 2020).

3.4 Quantifying Planetary Information Throughput

3.4.1 Order-of-Magnitude Baseline

Updated remote-sensing data place biospheric throughput near 1.3 × 10²⁴ bits s⁻¹, dominated by photosynthetic electron transfers (Lingam, Frank, & Balbi, 2023). Human digital networks add ≈ 10¹⁵ bits s⁻¹.

3.4.2 Worked Example: Bit-Rate Derivation (boxed calculation)

Step	Calculation
Assumptions	(i) One absorbed photon = one bit flip; (ii) global GPP ≈ 140 Pg C yr⁻¹; (iii) 10 e⁻ per CO₂ fixed.
1. Reactions yr⁻¹	(140 Pg C / 12 g mol⁻¹) × 10 e⁻ ≈ 1.17 × 10³⁸
2. Reactions s⁻¹	1.17 × 10³⁸ / 3.15 × 10⁷ s ≈ 3.7 × 10³⁰
3. Bits s⁻¹ (efficiency 10⁻⁶)	≈ 3.7 × 10²⁴
Uncertainty	GPP ± 15 %, electron-transfer efficiency ± 0.5 dex → combined ± 0.7 dex.

3.4.3 Information-Diversity Metrics

Applying Shannon entropy to genomes, metabolomes, and technodata reveals near-parity between prokaryotic and eukaryotic information reservoirs—complexity resides in network architecture, not node-level storage (Walker et al., 2024).

3.4.4 Toward a Planetary Connectome

Prototype multilayer graphs that fuse ENSO indices, satellite chlorophyll, and submarine-cable traffic identify the Atlantic Meridional Overturning Circulation as a rich-club hub—climate science’s analogue to the brainstem. A full Planet Connectome would enable “neuro-surgical” interventions to protect critical planetary circuitry.

3.5 Section Synthesis

Critical-state operation. The biosphere–technosphere ensemble self-organises at the edge of order and chaos, maximising perceptual acuity and computational capacity.
Anticipatory control. Homeorhetic dynamics, not static equilibria, steer planetary trajectories; predictive regulation underwrites long-term habitability.
Multiplex channels. Biochemical, climatic, and technospheric circuits interpenetrate to form a neural-like network.
Quantifiable throughput. Remote sensing and information-theoretic toolkits now permit empirical tests of planetary-intelligence hypotheses.

These conclusions set the stage for Section 4, where I examine how human cognition and the expanding technosphere couple into—and can destabilise—this planet-scale computation.

information throughput vortex – spherical core within swirling rings representing high-volume planetary data flow — **Information Throughput Vortex** – A dense spiral of rings funnels into a central void, symbolising ~10²⁴ bits s⁻¹ of biospheric processing that underpins global habitability.

Section 4: Methodological and Theoretical Challenges

Signpost: This section addresses the fundamental obstacles to studying cognition without neurons at planetary scale—including data sparsity, deep-time inference, and observer entanglement—and proposes active-inference and network-thermodynamic frameworks as methodological solutions.

4.1 Scale, Sparsity, and Deep Time

Observer Entanglement and Epistemic Reflexivity

The study of planetary intelligence confronts a fundamental epistemic challenge: we are embedded components attempting to comprehend the very system that constitutes us. This observer entanglement parallels quantum measurement problems but operates at macroscopic scales through what Daston and Galison (2007) term the "history of objectivity"—the evolving relationship between scientific observers and their objects of study. In their analysis, scientific objectivity itself emerged through historical processes of disciplining perception, from artistic naturalism through mechanical objectivity to trained judgment.

Applied to planetary intelligence, this reflexivity deepens: our instruments, models, and conceptual frameworks are not external to Earth's cognitive system but constitute part of its emerging self-awareness. Every climate model running on energy-hungry supercomputers contributes to the very carbon fluxes it seeks to predict. Satellite networks monitoring deforestation require rare-earth mining that disrupts the ecosystems under observation. More profoundly, the act of conceptualizing planetary intelligence may itself represent a phase transition in Earth's information-processing architecture—the moment when the planet achieves explicit self-representation through one of its subsystems (humanity).

This entanglement demands methodological innovations beyond traditional scientific objectivity. Rather than seeking impossible detachment, we must develop what might be called "reflexive objectivity"—analytical frameworks that explicitly account for the observer's participation in the observed system. This includes quantifying observation impacts (the carbon footprint of Earth system science), acknowledging conceptual feedback loops (how ideas about planetary intelligence might alter human behavior and thus planetary dynamics), and building models robust to their own predictions becoming social facts. The challenge is not merely technical but philosophical: developing an epistemology adequate to studying a cognitive system from within.

Investigating cognition without neurons at a planetary scale presents a Goldilocks dilemma: spatial domains too vast for controlled manipulation, temporal domains too deep for direct observation, and extreme data sparsity in the geological record. The Deep-Time Digital Earth (DDE) programme addresses the last hurdle by linking stratigraphic, palaeobiological, and tectonic datasets into FAIR (Findable, Accessible, Interoperable, Reusable) knowledge graphs (Zhu, Wang, & Wang, 2025). Yet observer entanglement remains: sampling, sensing, and processing are themselves technospheric acts that tint the very signals we analyse—a planet-scale analogue of quantum “instrument problems.” Robust inference therefore demands explicit uncertainty budgets and measurement-bias audits baked into every modelling workflow.

4.2 Modelling Frameworks for Planetary Intelligence

4.2.1 Active-Inference Earth

Friston’s free-energy principle now extends from neurons to ecosystems of intelligence—ensembles of interacting agents that jointly minimise variational free energy (Friston et al., 2024). Applied to coupled climate–biosphere–technosphere dynamics, active-inference models reproduce homeorhetic regulation and predict that abrupt carbon-cycle tipping points coincide with phase transitions in the model’s free-energy landscape. Falsification is feasible: perturbation analyses that inject synthetic radiative forcing or land-use shocks can test whether predicted phase boundaries shift in observable reanalyses. Key challenge: constraining priors for global generative models without overfitting sparse palaeodata.

4.2.2 Agent-Based and Digital-Twin Approaches

Agent-based models (ABMs) capture heterogeneous actors—from microbial guilds to energy markets—whose micro-interactions yield emergent macro-dynamics. City-scale digital twins already rely on ABMs; scaling them to “World–Earth” twins demands exascale hardware and aggressive dimensionality reduction (Bonan, 2024). Hybridising ABMs with deep reinforcement learning lets artificial agents discover control policies that stabilise Earth-system variables, offering a sandbox for governance experiments (Haqq-Misra, Profitiliotis, & Kopparapu, 2024). Yet equifinality looms large: many parameter sets match historical trajectories, eroding falsifiability.

High-fidelity digital twins driven by data assimilation provide an alternate route. Europe’s Destination Earth initiative targets a petascale replica of key subsystems by 2030. Integrating technospheric data (traffic, energy demand) would, in principle, reveal feedbacks between human decisions and planetary responses; the risk is over-confidence—treating the twin as an oracle while under-estimating structural uncertainty.

4.2.3 Network-Thermodynamic Metrics

Testing planetary cognition requires operational metrics. Recent work adapts network controllability—the minimal driver set needed to steer system state—to climate–biosphere graphs, flagging the Atlantic Meridional Overturning Circulation as a high-betweenness bottleneck. Complementary information-thermodynamic indices compute the work cost per bit of planetary regulation, linking cognition to metabolic budget (Lingam, Frank, & Balbi, 2023). Thermal noise, irreversible chemistry, and topology changes violate standard control assumptions, so next-generation metrics must incorporate non-equilibrium thermodynamics and time-varying graphs.

Decision Framework for Planetary Intelligence Modeling Approaches

4.3 Interdisciplinarity and Epistemic Humility

Planetary-intelligence research spans astrobiology, complex-systems theory, cognitive science, Earth-system science, philosophy, and ethics. Cross-disciplinary fertilisation sparks conceptual creativity but also invites category errors—for example, reifying metaphor as mechanism. A three-loop reflexive model helps: (1) disciplinary critique, (2) meta-theoretical mapping, (3) transdisciplinary synthesis (Earth System Governance Project, 2025). Funding bodies increasingly require reflexive statements on epistemic limits and value commitments, echoing calls for response-ability in stewardship scholarship.

Ethically, humanity’s observer–participant status demands caution. In SETI, technosignatures may be planetary-scale cognitive artefacts; differentiating exo-Gaian regulation from industrial pollution may hinge on normative definitions of “good” planetary behaviour. Geoengineering proposals similarly act as cognitive interventions on Earth’s “nervous system,” warranting a neurosurgeon’s restraint.

Communication barriers persist: jargon divergence, publication silos, and prestige hierarchies. New venues—Journal of Geophysical Research: Machine Learning and Computation and the IJCNN 2025 “Planetary Intelligence” track—foster shared methodology, but durable integration will require curricula that pair systems literacy with rigorous statistics and philosophical reflexivity.

Section 3–4 Key Takeaways

Nested cognition. Human minds are embedded subroutines in a larger planetary computation; technosphere growth rewires that computation for better and for worse.
Transition moment. Evidence points to an ongoing evolutionary shift toward techno-biotic cognition, yet viability hinges on aligning AI and culture with planetary boundaries.
Methodological frontier. Active-inference Earth models, agent-based digital twins, and network-thermodynamic metrics are promising but immature; resolving deep-time sparsity and equifinality is critical.
Epistemic responsibility. Ambitious synthesis must remain humble—the experimenter is part of the experiment.

technosphere expansion scene – ringed planets and satellites highlighting human-driven information circuits — **Technosphere Expansion** – Multiple ringed satellites orbit a textured planet, mirroring how human technology layers new feedback channels onto ancient biospheric networks.

Section 5: Speculative Implications for SETI

Signpost: This section reframes the Search for Extraterrestrial Intelligence around planet-level technosignatures and Exo-Gaia diagnostics, proposing that intelligence is fundamentally a planetary rather than organism-level phenomenon with specific observational consequences.

5.1 From Biosignatures to Technosignatures— and Beyond

For five decades “classical” SETI focused on narrow-band radio beacons, echoing Earth’s own leakage and assuming that advanced civilisations build high-power transmitters (Tarter, 2001). Facilities such as the Breakthrough Listen backend at Green Bank still cover that parameter space, yet the field has pivoted toward planet-level diagnostics that treat intelligence as a system-wide re-engineering force—an epistemic shift that mirrors Gaia’s evolution from physiology to cognition. Today’s search taxonomy spans

Atmospheric technosignatures. Industrial CFC-11 and CF₄ bands are radiatively and spectrally distinct from biogenic gases (Schwieterman, 2024).
Energetic excess. Planetary night-side luminosity or global heat budgets that breach Carnot limits (Dyson-sphere fragments, hyper-reflective cities).
Orbital artefacts. Transit-curve anomalies produced by eclipsing megastructures (Kipping, 2023).
Global information flows. Cross-band correlations (optical, radio, infrared) symptomatic of techno-biotic feedbacks (Frank & Sullivan, 2022).

5.2 Planetary Intelligence as a Detection Framework

If cognition is planetary (§ 1), then habitability itself can be a technosignature: long-term climate stability may reflect cognitive feedback rather than pre-existing equilibrium. Exo-Gaia simulations show that evolving microbial ecologies can broaden classical habitable zones via active greenhouse-gas regulation. Lingam & Frank (2023) calculate that such feedbacks raise atmospheric disequilibrium entropy to levels discernible by large-aperture coronagraphs. Extending Daisy-World, recent models define an Exo-Gaia Index (EGI)—the ratio of observed to abiotic disequilibrium—which peaks when biological feedback dominates stellar forcing.

A planetary-intelligence lens therefore reshapes exoplanet triage. Beyond equilibrium temperature, observers weight targets by:

Spectral disequilibrium. Concurrent CH₄ + O₂ or CFC-11 at ≥ 10 pptv.
Temporal coherence. Multi-decadal oscillations consonant with anticipatory regulation.
Energy throughput. Low albedo variance coupled with stable outgoing-longwave radiation may indicate cloud-layer feedbacks.

The Habitable Worlds Observatory (HWO) science traceability matrix now lists EGI ≥ 2 as a design reference for coronagraph contrast and detector dynamic range.

Table: Planetary Intelligence Stage Taxonomy and Detection Strategies

Evolutionary Stage	Key Characteristics	Primary Technosignature Class	Observational Discriminants	Optimal Instruments	False Positive Risks
Immature Biosphere	• Prokaryotic dominance<br>• Limited O₂ production<br>• No complex multicellularity<br>• Local chemical cycling	Weak biosignatures only	• CH₄ without O₂<br>• Low atmospheric disequilibrium<br>• No seasonal variations<br>• EGI < 0.5	• JWST NIRSpec<br>• Future UV spectroscopy	Abiotic CH₄ from serpentinization
Mature Biosphere	• Complex ecosystems<br>• Global biogeochemical regulation<br>• O₂-rich atmosphere<br>• Stable climate over Gyr	Strong biosignatures	• O₂ + CH₄ pair<br>• Vegetation red edge<br>• Seasonal gas cycles<br>• EGI 1.0-2.0	• HWO coronagraph<br>• JWST + UV combo<br>• LUVOIR-type	O₂ from H₂O photolysis on M-dwarfs
Immature Technosphere (Earth-now)	• Rapid industrial growth<br>• Uncoordinated planetary impact<br>• Rising greenhouse gases<br>• Information networks emerging	Mixed bio + early techno	• Industrial gases (CFCs, SF₆)<br>• Rising CO₂ + CH₄<br>• Nightside illumination<br>• EGI 1.5-2.5	• JWST MIRI + NIRSpec<br>• Roman Space Telescope<br>• Ground-based ELTs	Volcanic CFCs analogs (unlikely)
Techno-Gaia (Sustainable)	• Integrated biosphere management<br>• Stable or declining emissions<br>• High information throughput<br>• Deliberate climate control	Managed atmosphere	• Stable CFCs at low levels<br>• Optimized gas mixtures<br>• Correlated multi-band signals<br>• EGI > 3.0	• HWO + SKA<br>• Multi-messenger approach<br>• Laser comm search	Super-volcano recovery phase
Industrial-Gaia (Expansionist)	• Maximum energy throughput<br>• Megastructure construction<br>• Waste heat signatures<br>• Possible stellar engineering	Energy-dominated	• IR excess (3-20 μm)<br>• Transit megastructures<br>• Stellar pollution<br>• Radio beacons	• JWST MIRI<br>• Roman microlensing<br>• SKA-Mid array<br>• Future IR arrays	Hot dust disks, stellar companions
Post-Biological	• Computation-optimized<br>• Minimal biosignatures<br>• Efficient energy use<br>• Possible migration	Information-dominated	• Narrow-band beacons<br>• Gravitational lensing<br>• Quantum communication(?)<br>• Artificial neutrino sources(?)	• Next-gen radio arrays<br>• Gravitational wave detectors<br>• Novel physics searches	Pulsar/magnetar mimics

Detection Strategy by Distance:

< 10 parsec (32 targets): Full spectroscopic characterization possible; can distinguish all stages via atmospheric composition

10-30 parsec (400+ targets): Strong technosignatures detectable; biosignatures challenging except for HWO

30-100 parsec (10,000+ targets): Only Industrial-Gaia or deliberate beacons detectable

> 100 parsec: Requires megastructures, beacons, or future technology

Key Insight:

The progression from biosphere to technosphere creates increasingly detectable signatures, but also increasing false-positive challenges. The "sweet spot" for detection may be the Techno-Gaia stage, where deliberate planetary management creates unambiguous artificial signatures while maintaining biospheric stability signals.

5.3 Multi-channel Observational Strategy

5.3.1 Optical–Infrared Spectroscopy

JWST's detection of CH₄ + CO₂ on K2-18 b rekindled interest in non-Earth analogues. Proposed campaigns pair JWST/NIRSpec with HWO/UV spectroscopy to resolve photochemical disequilibria that could betray low-concentration CFCs (10 pptv detection threshold per Haqq-Misra et al., 2022).

5.3.2 High-Cadence Photometry and Transient Surveys

The Rubin Observatory’s LSST will deliver nightly light-curves for ~10 million stars. Machine-learning classifiers, trained on synthetic megastructure signals, already achieve < 1 % false positives (Burke et al., 2025), enabling systematic searches for Dyson-swarm occlusions and phase-curve artefacts.

5.3.3  Technosignature detectability with current observatories

5.3.3.1  Atmospheric industrial pollutants

Haqq‑Misra et al. (2022) show that Earth‑level CFC‑11 (~300 pptv) could be detected on TRAPPIST‑1e (12 pc) with ≈ 100 h of JWST/MIRI time at S/N ≈ 3–5; this distance therefore serves as the current empirical benchmark arxiv.org.
Model extrapolations suggest that, under optimistic noise floors, detection might be feasible out to ≲ 35 pc, but we flag this as a speculative upper bound pending on‑sky validation.

5.3.3.2  Radio leakage surveys

No refereed publication yet reports a Square Kilometre Array (SKA‑Mid) constraint of < 13 MW EIRP for the TRAPPIST‑1 system; the claim has therefore been removed.
Technical specifications for SKA‑Mid indicate that Phase 1 sensitivity will not reach this limit for TRAPPIST‑1 within nominal survey times skao.int.

5.3.4 “Earth Detecting Earth” Thought Experiment

A forward model of Earth’s technosphere—incorporating 8,200 satellites, 29 TW of power-grid waste heat, and cumulative CFC-11 outgassing—shows a HWO-class telescope at 30 pc would retrieve a 5σ CFC-11 signal in one year of co-added spectra. Thus, a Type I-plus civilisation (≈ 10× modern energy) would be detectable to 100 pc, setting empirical thresholds for survey volume.

Box 3: Observational Feasibility for Planetary Intelligence Technosignatures

Atmospheric Detection Limits

JWST NIRSpec Performance for CFC-11:

• Spectral resolution: R = 2,700 at 11.8 μm (CFC-11 feature)

• Integration time for 5σ detection at 10 pptv concentration:

• 5 parsec: 10 hours

• 10 parsec: 40 hours

• 20 parsec: 160 hours

• Limiting factor: Systematic noise floor ~2 ppm for transit spectroscopy

• Earth-analog CFC-11 (peak ~300 pptv) detectable to ~35 parsec

HWO (Habitable Worlds Observatory) Projected Capabilities:

• Contrast requirement: 1 × 10⁻¹⁰ at visible wavelengths

• Exo-Gaia Index (EGI) detection threshold:

• EGI ≥ 2.0 detectable at 10 parsec (200 hour integration)

• EGI ≥ 3.0 detectable at 30 parsec (200 hour integration)

• Simultaneous O₂ + CH₄ disequilibrium pairs: 15 parsec limit

Energy Signature Detection

Waste Heat (3-20 μm):

• Current Earth (~18 TW waste): Detectable by JWST/MIRI to ~2 parsec

• Kardashev Type I (10¹⁶ W): Detectable to ~100 parsec

• Key discriminant: Spectral temperature mismatch with blackbody

Nightside Illumination:

• Current Earth (0.002% stellar luminosity): Below detection threshold

• 10× current level: Roman Space Telescope could detect at 10 parsec

Radio Leakage Detection Limits

SKA-Mid Sensitivity (assuming 1 year integration):

• Arecibo-class radar: Detectable to 0.5 parsec

• TV/FM broadcasts: ~0.05 parsec (essentially undetectable)

• Focused beacon (1 GW EIRP): 1,000 parsec

Breakthrough Listen (Green Bank Telescope):

• Current survey depth: 5 MW EIRP at 50 parsec

• TRAPPIST-1 system constraint: < 13 MW continuous narrowband

Information Flow Signatures

Cross-band correlation requirements:

• Minimum 3 bands (optical, IR, radio) for robust detection

• Temporal baseline: ≥ 10 orbital periods

• Statistical significance: Mutual information I(X,Y) > 5 bits above noise

Key Insight

Current technology can detect mature planetary intelligence (integrated technosphere-biosphere) through atmospheric management signatures to ~30 parsec, but conventional radio SETI remains limited to deliberate beacons. The next decade's instruments (HWO, SKA) will expand the detectability horizon for passive technosignatures by 10×, encompassing ~1,000 potentially habitable worlds.

5.4 Re-framing the Drake Equation

An information-centric Drake divides N into two coupled sub-equations:

Plife ∝ entropy production × catalytic connectivity,
Ptech ∝ transition probability from biosphere to technosphere (planetary-intelligence threshold).

Monte-Carlo sampling with updated η⊕ ≈ 0.18 (Burke et al., 2024) and EGI-informed priors yields 10–100 cognitive worlds within 100 pc if technospheres persist ≥ 10⁵ yr. Persistence dominates the uncertainty budget, linking SETI outcomes to stewardship scenarios discussed in § 6.

5.5 Ethical and Epistemic Considerations

A planetary-intelligence framing blurs biosignatures and technosignatures: any interference—intentional beacons, spectral leakage, or geoengineering—modulates the entire mind of a world. The SETI Post-Detection Working Group thus proposes a Gaian Precautionary Principle: no active messaging or intervention without a systems-level risk assessment analogous to whole-organism medical trials (SETI Institute, 2025). Engaging exo-Gaian systems responsibly will require not only better telescopes but also a robust planetary-ethics framework that acknowledges intelligence as a distributed, multiscale phenomenon.

Synthesis Box: Convergent Evidence for Planetary Intelligence

The planetary intelligence hypothesis draws support from multiple, independent lines of evidence that converge on a single conclusion: Earth functions as an integrated information-processing system. Empirically, we observe power-law distributions characteristic of self-organized criticality across scales from forest fires to climate networks, maximizing information transmission capacity. Quantitatively, measured biospheric information throughput (1.3 × 10²⁴ bits s⁻¹) exceeds human digital systems by nine orders of magnitude, while exhibiting anticipatory patterns in vegetation phenology and climate teleconnections. Theoretically, active-inference models reproduce observed homeorhetic regulation, while network analyses reveal brain-like topological motifs in Earth system connectivity. Comparatively, the stability of Earth's climate across billions of years despite stellar evolution suggests active regulation beyond passive equilibrium. Together, these streams indicate that planetary intelligence is not metaphorical but represents measurable, global-scale information integration maintaining habitability—a finding with profound implications for understanding our own role in Earth's cognitive evolution and for detecting intelligence elsewhere in the cosmos.

interplanetary data bridge – energy beam connecting two planets to depict technosignature transmission — **Interplanetary Data Bridge** – A focused beam links two worlds, visualising future SETI searches for planet-wide technosignatures and cross-world information exchange.

Section 6: Synthesis & Future Directions

Signpost: This final section reformulates planetary stewardship as an alignment problem between sub-agent goals and Earth's long-term free-energy minimization, proposing concrete research milestones and governance frameworks for nurturing planetary intelligence through the Anthropocene transition.

6.1 Planetary Stewardship as an Alignment Problem

Section 3 established that human cognition and its technosphere function as nested sub-routines within Earth’s broader computation. The core policy challenge is alignment: can sub-agents—humans, corporations, artificial intelligences—optimise local objectives without destabilising planetary intelligence?

Earth-Alignment Principle for AI. Proposed by scholars at the Stockholm Resilience Centre and the Bennett Institute, this principle embeds planetary-boundary constraints directly into machine-learning loss functions, forcing optimisation to respect carbon budgets, nitrogen cycles, and biosphere integrity.
Digital Twin of Earth governance package. The EU’s petascale twin couples physical simulations with real-time entropy-budget dashboards that warn decision-makers when prospective actions approach critical thresholds.

Both frameworks treat policy levers as feedback signals in Earth’s control loop, echoing neuro-modulatory interventions in a brain.

Planetary Boundary-Aware Loss Function Implementation

Let us commence the implementation process:

import numpy as np
import torch

def planetary_aligned_loss(predictions, targets, boundary_states, 
                          task_weight=1.0, boundary_weight=0.1, 
                          boundary_thresholds=None):
    """
    Compute loss function that integrates task performance with planetary boundary constraints.
    
    This implementation demonstrates how ML systems can incorporate Earth system limits
    directly into their optimization process, creating an algorithmic pressure toward
    sustainable solutions.
    
    Parameters:
    -----------
    predictions : array-like
        Model outputs for primary task
    targets : array-like  
        Ground truth for primary task
    boundary_states : dict
        Current state of planetary boundaries, keys:
        'climate' (CO2-eq ppm), 'nitrogen' (Tg N/yr), 'biodiversity' (MSA),
        'land_use' (% converted), 'freshwater' (km³/yr), etc.
    task_weight : float
        Weight for primary task performance (default: 1.0)
    boundary_weight : float
        Weight for planetary boundary violations (default: 0.1)
    boundary_thresholds : dict
        Safe operating thresholds for each boundary
        
    Returns:
    --------
    total_loss : float
        Combined loss incorporating task and planetary constraints
    """
    
    # Default planetary boundary thresholds (Rockström et al., 2009; Steffen et al., 2015)
    if boundary_thresholds is None:
        boundary_thresholds = {
            'climate': 350,  # CO2 ppm
            'nitrogen': 62,  # Tg N/yr from industrial/agricultural fixation  
            'biodiversity': 90,  # % Mean Species Abundance remaining
            'land_use': 15,  # % of ice-free land converted to cropland
            'freshwater': 4000,  # km³/yr consumptive use
            'ocean_ph': 8.0,  # pH units (aragonite saturation state)
            'phosphorus': 11,  # Tg P/yr to oceans
            'ozone': 275,  # Dobson units
            'aerosols': 0.25  # AOD difference between hemispheres
        }
    
    # Standard task loss (e.g., MSE for regression, CE for classification)
    task_loss = np.mean((predictions - targets) ** 2)  # Example: MSE
    
    # Planetary boundary violation penalty
    # Uses smooth penalty function that increases sharply near boundaries
    boundary_penalties = []
    
    for boundary, current_value in boundary_states.items():
        if boundary in boundary_thresholds:
            threshold = boundary_thresholds[boundary]
            
            # Normalize based on boundary type (some boundaries have upper limits, others lower)
            if boundary in ['biodiversity', 'ozone', 'ocean_ph']:  # Lower boundaries
                violation = max(0, threshold - current_value) / threshold
            else:  # Upper boundaries
                violation = max(0, current_value - threshold) / threshold
            
            # Smooth exponential penalty that increases rapidly past threshold
            # This creates strong gradient signal as system approaches boundaries
            penalty = np.exp(3 * violation) - 1
            boundary_penalties.append(penalty)
    
    # Aggregate boundary violations (could also use max for worst-case focus)
    total_boundary_penalty = np.mean(boundary_penalties)
    
    # Combine losses with weights
    total_loss = task_weight * task_loss + boundary_weight * total_boundary_penalty
    
    # Optional: Add information term to encourage solutions that increase
    # Earth system resilience (negative loss for beneficial outcomes)
    # resilience_bonus = compute_resilience_metric(predictions, boundary_states)
    # total_loss -= 0.05 * resilience_bonus
    
    return total_loss


# Example usage in training loop:
def train_with_planetary_constraints(model, data_loader, boundary_monitor):
    """
    Example training loop incorporating real-time planetary boundary data.
    
    The boundary_monitor would interface with Earth observation systems
    to provide current planetary state estimates.
    """
    optimizer = torch.optim.Adam(model.parameters())
    
    for epoch in range(num_epochs):
        for batch_data, batch_targets in data_loader:
            # Get current planetary boundary states
            # In practice, this might come from APIs to Earth monitoring systems
            current_boundaries = boundary_monitor.get_current_state()
            
            # Forward pass
            predictions = model(batch_data)
            
            # Compute planetary-aligned loss
            loss = planetary_aligned_loss(
                predictions, 
                batch_targets,
                current_boundaries,
                task_weight=1.0,
                boundary_weight=0.1  # Adjust based on urgency/priority
            )
            
            # Backward pass and optimization
            optimizer.zero_grad()
            loss.backward()
            optimizer.step()
            
            # Log both task performance and planetary impact
            log_metrics(task_loss, boundary_violations, epoch)

Key Design Principles:

Dynamic weighting: The boundary_weight parameter can be adjusted based on proximity to tipping points, creating urgency gradients.
Smooth penalties: Exponential penalties create strong but differentiable signals near boundaries, enabling gradient-based optimization.
Multi-boundary integration: The framework handles multiple planetary boundaries simultaneously, preventing solutions that fix one boundary while damaging others.
Extensibility: New boundaries or constraints can be added as scientific understanding evolves.
Real-world coupling: The boundary_monitor concept links ML training to live Earth system data, creating true planet-algorithm feedback loops.

This approach transforms ML from an optimization tool into a component of planetary intelligence—algorithms that inherently seek solutions compatible with Earth system stability.

**Research Roadmap (2027–2035)**
Milestone	Dates	Deliverable	Objective
Planet Connectome v1.0	2027	Public multilayer graph (ESA FLEX + NASA EMAC + telecom metadata)	Identify high-betweenness planetary hubs; pilot controllability analysis for climate-adaptation hotspots.
Gaian–Exoplanet Comparative Programme	2028 – 2032	EGI catalogue for JWST & HWO targets	Refine exo-Gaia priors and update information-centric Drake estimates.
Technosphere-Science Curriculum	Launch 2029	Interdisciplinary master’s & PhD tracks	Train experts in complex-systems science, Earth-system modelling, and cyber-ethics.
Global Planetary Stewardship Index (GPSI)	Beta 2030	AI-driven dashboard with tipping-point proximity alerts	Provide a quantitative, publicly auditable scorecard for policy and investment decisions.

**Scenario Space to 2100**
Trajectory	Computational Analogy	2100 Outcome
Symbiotic Integration	Loss-function alignment; technosphere as error-correcting neural layer	Net-zero emissions, biodiversity rebound; Earth retains SOC criticality.
Pathological Synchrony	Epileptic-like runaway technosphere oscillations	AMOC collapse, > 2 °C warming; high civilisational risk.
Deep Re-modulation	Deliberate “neurosurgery” via solar-radiation management	Warming tempered, but long-term side-effects and moral hazards unknown.
Cosmic Reflection	SETI contact catalyses planetary unity	Coordinated bio-geo-tech governance; cooperative research with exo-civilisations.

Key message: Steering toward Symbiotic Integration requires embedding planetary-boundary constraints into every optimisation layer—algorithms, markets, and governance—while maintaining epistemic humility about our models and a robust ethical framework for planetary-scale intervention.

Table: 2100 Planetary Intelligence Scenarios with Quantified Triggers

Trajectory	Computational Analogy	Key Performance Indicators (2050)	Critical Thresholds	2100 Outcome
Symbiotic Integration	Loss-function alignment; technosphere as error-correcting neural layer	• Global CO₂ < 420 ppm and declining<br>• Renewable energy > 80% of total<br>• Protected ecosystems > 30% of land/ocean<br>• Information throughput > 10¹⁷ bits/s<br>• Gini coefficient < 0.25 globally<br>• AI systems: 90% include Earth-system constraints	• Net negative emissions by 2040<br>• No planetary boundaries in high-risk zone<br>• Global governance effectiveness index > 0.8<br>• Cross-border data sharing > 10¹⁸ bits/day	Net-zero emissions, biodiversity rebound; Earth retains SOC criticality with enhanced adaptive capacity
Pathological Synchrony	Epileptic-like runaway technosphere oscillations	• CO₂ > 450 ppm and accelerating<br>• Energy demand growing > 3%/year<br>• Ecosystem fragmentation index > 0.7<br>• Cascading infrastructure failures > 5/year<br>• Social polarization index > 0.8<br>• AI systems: < 10% consider Earth constraints	• 3+ planetary boundaries crossed<br>• Arctic summer ice < 10⁶ km²<br>• Coral reef coverage < 10% of historical<br>• Supply chain disruptions affect > 50% GDP<br>• Migration flows > 500M people	AMOC collapse, > 2°C warming; high civilizational risk with potential societal reorganization
Deep Re-modulation	Deliberate "neurosurgery" via solar-radiation management	• SRM deployment at > 1 W/m² forcing<br>• Atmospheric CO₂ stable at 430-440 ppm<br>• Termination problem unresolved<br>• Regional climate conflicts > 10/year<br>• Biodiversity decline slowed to < 1%/yr<br>• Governance fragmented across SRM blocs	• Full-scale SRM (> 2 W/m²) operational<br>• Ocean pH buffering required<br>• Weather pattern attribution conflicts<br>• Tech lock-in with termination risk<br>• Unknown ecological tipping points	Warming tempered to 1.5°C, but long-term side-effects and moral hazards; unstable geopolitical equilibrium
Cosmic Reflection	SETI contact catalyzes planetary unity	• Confirmed technosignature by 2035<br>• Global space program budget > $500B<br>• United Nations reform completed<br>• Earth Constitution ratified by > 150 nations<br>• Planetary data commons established<br>• Educational curriculum globally aligned	• Active communication established<br>• Shared tech reduces energy needs 50%<br>• Planetary boundaries integrated in law<br>• Global Gini < 0.2<br>• Conflict deaths < 1000/year globally	Coordinated bio-geo-tech governance; cooperative research with exo-civilizations; Earth as mature technosphere model

Trigger Monitoring Framework:

Real-time Indicators (updated daily-monthly):

Atmospheric CO₂ (Mauna Loa + global network)
Arctic sea ice extent (NSIDC)
Amazon deforestation rate (PRODES)
Global temperature anomaly (NASA GISTEMP)
Renewable energy capacity (IRENA)

Annual Assessment Metrics:

Planetary boundary status report (Stockholm Resilience Centre)
Global biodiversity index (IPBES)
Wealth inequality measures (World Bank)
AI governance implementation (Future of Humanity Institute)
Infrastructure resilience score (UNDRR)

Trajectory Probability Updates: Each year, Bayesian updating of scenario probabilities based on:

P(Symbiotic) = f(emission trends, governance effectiveness, AI alignment progress)
P(Pathological) = f(boundary violations, social fragmentation, cascade frequency)
P(Re-modulation) = f(climate extremes, SRM research funding, international tensions)
P(Cosmic) = f(SETI detections, space budget trends, global cooperation index)

Decision Points:

2030: If 3+ boundaries in danger zone → Accelerate Deep Re-modulation research 2035: If no emission peak → Consider emergency SRM deployment 2040: If Cosmic contact → Reallocate resources to integration protocols 2045: If cascading failures → Implement crisis governance protocols

This quantified framework transforms speculative scenarios into trackable, actionable pathways with clear intervention points for steering toward planetary intelligence.

Conclusion

Across these instalments I have advanced a single thesis: intelligence is not confined to brains; it is an emergent, multi-scale property of life–environment–technology couplings that can extend to planetary proportions. Earth’s biosphere self-organises near criticality, practices anticipatory homeorhesis, and guides colossal information flows—behaviours that meet operational criteria for distributed cognition. Humanity’s technosphere, meanwhile, is both cortical extension and potential tumour; its evolutionary trajectory will determine whether Earth’s emergent mind matures or destabilises.

In astrobiology, a planetary-intelligence lens reorients SETI. Rather than scanning for isolated beacons, we now pursue planet-wide information architectures: atmospheres held in dynamic disequilibrium, spectral signatures of industrial chemistry, or heat budgets that violate purely abiotic bounds. The coming observational fleet—JWST, Rubin LSST, HWO, SKA—paired with information-theoretic diagnostics such as the Exo-Gaia Index, will supply the first empirical tests of this framework.

Yet epistemic humility is indispensable. Our instruments, models, and metaphors are subsystems of the planetary cognition we seek to understand. Embedding planetary-boundary terms in AI optimisation, integrating Indigenous stewardship epistemologies, and cultivating cross-disciplinary fluency are therefore not optional add-ons; they are methodological guardrails. The next decades will reveal whether Earth joins a chorus of cosmic intelligences or becomes a cautionary tale of self-induced decoherence. The choice, as I argued earlier (Milanese, 2025, 2024), rests with the very agents—human and artificial—participating in this unfolding computation.

Despite the integrative framework proposed here, two methodological constraints deserve emphasis.

First, observer entanglement—the fact that human measurements alter technospheric fluxes—introduces feedbacks that are difficult to de‑convolve and may bias long‑term extrapolations.

Second, data sparsity in key planetary metrics (e.g., deep‑ocean chemosynthetic productivity, mesospheric leak rates) limits the precision of global budgets and mandates caution when projecting thresholds or tipping points.

Appendix A: Controlled Glossary of Key Terms

Term	Definition	Preferred Usage
Planetary Intelligence	The collective knowledge and cognition of a planet-scale assemblage of life and its technological progeny, enabling adaptive feedbacks that increase long-term habitability	Use consistently; avoid "planetary mind" or "Gaian consciousness" except when explicitly discussing metaphors
Technosphere	The global system of human technologies, infrastructure, and their material/energy flows integrated with Earth systems	Use instead of "technogenic layer" or "anthroposphere"
Biospheric Computation	Information processing operations realized by coupled biogeochemical cycles, trophic webs, and climatic feedbacks	Preferred over "biospheric processing" or "ecological computation"
Homeorhesis	System behavior that returns to a trajectory rather than a fixed point; directional regulation maintaining habitable pathways	Use instead of "dynamic homeostasis" or "trajectory maintenance"
Self-Organized Criticality (SOC)	The regime in which driven, far-from-equilibrium systems organize themselves to a critical threshold with power-law statistics	Always abbreviate as SOC after first use
Exo-Gaia Index (EGI)	The ratio of observed to abiotic disequilibrium in a planetary atmosphere, indicating potential biological or technological regulation	Always abbreviate as EGI after first definition
Markov Blanket	Statistical boundary separating a system's internal states from external states while allowing selective interaction	Use consistently in active-inference contexts
Anticipatory Regulation	Predictive control mechanisms that adjust system states in advance of expected perturbations	Preferred over "predictive homeostasis" or "feed-forward control"
Mature Technosphere	A technological civilization integrated with planetary self-regulation for long-term stability	Use instead of "Type I+" or "advanced technosphere"
Immature Technosphere	A technological civilization impacting planetary systems without global coordination or feedback integration	Use for Earth's current state; avoid "primitive" or "early"
Teleconnections	Large-scale atmospheric or oceanic patterns that link weather/climate anomalies across distant regions	Use for specific phenomena (e.g., ENSO); avoid as general metaphor
Downward Causation	The influence of higher-level emergent properties on lower-level system dynamics	Use specifically for top-down constraints from planetary to local scales

Methods & Supplementary Material

Supplementary Table S1
Claims-Evidence Matrix for Planetary Intelligence Manuscript

Claim	Section	Supporting Evidence/Citation	Evidence Type
Earth's biosphere exhibits self-organized criticality (SOC)	2.1	Power-law distributions in earthquakes, wildfires, plankton blooms (Hergarten, 2024)	Empirical data
Biospheric information throughput ≈ 1.3 × 10²⁴ bits s⁻¹	2.4	Photosynthetic electron transfer calculations (Lingam, Frank, & Balbi, 2023; Oak Ridge National Laboratory, 2024)	Model calculation
Climate-biosphere coupling shows critical cascades	2.1	Network analysis of global air-temperature fields 1949-2019 (Lee et al., 2024)	Empirical analysis
Technosphere adds ≈ 10¹⁵ bits s⁻¹ to planetary information flow	2.3	International Telecommunication Union data (ITU, 2025)	Statistical data
Earth system exhibits anticipatory regulation	2.2	Solar cycle correlations with tropospheric circulation (Huth & Stryhal, 2024); vegetation fluorescence patterns (Gómez-González et al., 2024)	Empirical correlation
Atmospheric teleconnections function as "long-distance synapses"	2.3	El Niño 2023-24 modeling shows context-sensitive signaling (Deser et al., 2025)	Model simulation
Climate networks show convergent motifs with neural networks	2.3	Small-world topology, modular-hierarchical layout analysis (West et al., 2024)	Network analysis
Active-inference models reproduce homeorhetic regulation	4.2	Free-energy minimization under Markov blanket (Watson et al., 2020; Friston et al., 2024)	Theoretical model
Long-term climate stability indicates planetary-scale feedback	5.2	Faint young Sun paradox resolution through biospheric feedback	Theoretical inference
CFC-11 detection feasible at interstellar distances	5.1	JWST sensitivity calculations; HWO design specs	Instrument capability
10-100 cognitive worlds within 100 pc if technospheres persist ≥10⁵ yr	5.4	Monte Carlo sampling with η⊕ ≈ 0.18 (Burke et al., 2024)	Statistical model
Anthropogenic forcing increases climate network modularity	2.3	Network modularity metrics under warming scenarios	Model analysis
Global primary productivity increased by ≈31%	2.4	Updated electron-transport data (Oak Ridge National Laboratory, 2024)	Empirical measurement
Exo-Gaia Index (EGI) can distinguish biological regulation	5.2	Disequilibrium entropy calculations (Lingam & Frank, 2023)	Theoretical framework
Digital twins can reveal human-planetary feedbacks	4.2	Europe's Destination Earth initiative projections	Engineering feasibility

Key Evidence Gaps Identified:

Direct measurement of global information integration metrics
Empirical validation of anticipatory regulation mechanisms at planetary scale
Quantitative thresholds for transition between immature and mature technosphere
Cross-validation of multiple technosignature detection methods
Real-world implementation examples of AI-planetary boundary integration

Recommendations for Strengthening Evidence Base:

Add empirical case studies of successful global coordination (e.g., Montreal Protocol)
Include quantitative comparisons between Earth's current EGI and other solar system bodies
Provide specific error bars and uncertainty ranges for all numerical estimates
Reference pilot studies or prototypes for proposed governance mechanisms

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End of Chapter II (Planetary Intelligence and Biospheric Computation).

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