When Did the Waters Part?

A Quantitative Reconstruction of the Post-Catastrophe Climate, Sea Level, and Dispersal Infrastructure

Part Two of the Diaspora Series

Disclaimer: This paper was developed collaboratively between Claude (Anthropic) and D. L. White. Climate forcing was independently reviewed by Grok (xAI). The paper builds on the qualitative framework established in "Where Did the Dove Find Peace?" (Part One) and should be read as a continuation of that work.

← Return to Part One: "Where Did the Dove Find Peace?"

The Clock Starts

The first paper in this series established ten propositions describing the post-catastrophe recovery as a practical engineering problem. The tectonic “main event” was brief and violent. The landscape resumed rather than restarted. The new warm ocean basins were an inevitable consequence. The ice age followed necessarily.

Those propositions were qualitative — practical inferences from the Genesis account treated as an engineering specification. This paper examines whether the specifications are plausible by making them quantitative.

Every number in this paper derives from a single source: the velocity of the tectonic plates as a function of time. That velocity curve — constrained by two primary observations (total continental displacement of approximately 5,000 km and the modern GPS-measured velocity of approximately 5 cm/yr) — determines the rate of ocean heating, the depth of new basins, the height of rising mountains, the intensity of volcanic forcing, and the area of new seafloor. Five outputs from one master equation (plate velocity as a function of time), constrained by two primary observations and the phase transition recorded in the narrative at day 40.

The question is not whether the waters parted. The first paper established that they did — mountains rose, basins deepened, ice accumulated. The question is when. When did the sea level drop far enough to connect Asia to North America? When did the corridor to Australia open? When did the bridges close, locking each continent's founding roster in place?

The answer, as it turns out, is early — but not instantaneous. The new ocean basins must first form solid lithosphere before they can deepen, and that sets the starting gun for the sea level drop.

A critical point must be established before the numbers begin. The recovery does not start when the animals exit the ark at day 371. It does not start when the ark grounds at day 150. It starts during the catastrophe itself. Mountains thrust upward by plate convergence push above the water surface within weeks. Rain falls on exposed rock immediately. Salt washes from soil within days under extreme precipitation. Pioneer vegetation — from surviving root systems, not distant seed sources — resumes growth on volcanic ash within weeks of exposure. Under secondary succession accelerated by extreme precipitation and volcanic ash fertilization, pioneer vegetation on newly exposed highlands reaches measurable biomass within three to nine months. This is consistent with Krakatoa and Mount St. Helens recovery rates, and likely faster given surviving root systems rather than wind-dispersed seed colonization. By the time the ark grounds at day 150, the Tibetan Plateau has been catching rain and growing things for months. The Ethiopian Highlands, the Andes, and every other landmass above 3,000 meters are well into recovery. The olive leaf that the dove returns at day 272 is not the beginning of recovery. It is a measurement taken months into a recovery already well underway. By the time the ark's passengers descend the ramp at day 371, the highest terrain has supported active plant growth for the better part of a year. The world they walk into is not post-catastrophe. It is mid-recovery.

The Master Clock

Two Phases, One Curve

The plate velocity profile follows the universal signature of material failure under stored stress. Every system that fractures — pressure vessels, dams, earthquake faults, landslides — exhibits the same pattern: explosive initiation as stored energy releases, rapid deceleration as friction engages, then slow exponential decay toward equilibrium. Continental fracture is no exception.

The Genesis text marks this transition explicitly. The Hebrew word mabbul — the violent, catastrophic deluge — appears twelve times in the flood narrative but ceases after day 40. After that, the text uses only mayim (waters). The vocabulary shift corresponds to a physical phase transition.

Phase A (days 0–40, the mabbul): The crust fractures. Peak plate velocity reaches approximately 84 km/day (3.5 km/hour) — roughly walking speed. This sounds slow until one considers that an entire continent is sliding at this rate, displacing the ocean floor across thousands of kilometers of fault length. The tsunamis generated by this displacement are continental in scale. Phase A accounts for approximately 419 km of total displacement (8.4%) with a deceleration time constant of 5 days. By day 40, velocity has dropped by a factor of 3,000.

Phase B (day 40 onward, the mayim): The system transitions from explosive fracture to sustained viscous flow. Starting velocity of this phase is approximately 10.3 km/yr, decaying exponentially with a time constant of 445 years (half-life 309 years). Phase B accounts for the remaining 4,581 km of displacement (91.6%). This is the phase that builds basins, raises mountains, generates hydrothermal heat, and drives the ice age.

The engineering specification sets the phase transition at day 40 — the narrative's shift from mabbul to mayim — providing the third anchor point for the model. Together with the two observational constraints, the physics yields a unique solution for the remaining parameters.

The detailed derivation and parameter sensitivity analysis are presented in Appendix A.

The Warm Ocean

The catastrophe delivers an enormous quantity of heat to the ocean. The total energy delivered — fixed by two observables (the displaced volume of new lithosphere and the modern measured heat flux through the Atlantic ocean floor) — is approximately 1.41 × 10²⁸ joules. The full derivation, including the three-phase delivery mechanism (charging, boiling discharge, conductive tail) and the basin-resolved heat budget, is presented in Appendix F of the foundational standalone ("What Broke the Foundations?").

The thermal architecture is asymmetric. The Atlantic and Indian rift basins receive direct emplacement of new mantle material at the surface; their basin floors boil seawater at the 100°C surface boundary throughout the active discharge phase (approximately 240–460 years, depending on the effective boiling flux). The Pacific is fundamentally different. It is the remnant of the pre-event ocean floor — old, cold, dense lithosphere that has not yet been consumed by subduction. No new crust forms in the Pacific. No mantle is exposed at its floor. It receives no direct tectonic heat. The Pacific warms only indirectly — through atmospheric heat redistribution (latent heat released when moisture evaporated from the hot basins condenses and precipitates elsewhere) and through circum-Antarctic ocean circulation, where the temperature differential between basins drives vigorous mixing.

The thermal contrast between these basins is extreme. The Atlantic and Indian basins boil briefly and cool over centuries. The Pacific remains near its pre-event temperature throughout the early recovery. The CPT standalone's heat budget (Appendix F) quantifies the full timeline: the Atlantic returns to approximately 30°C by year 963; the Pacific peaks at approximately 16°C.

This asymmetry resolves the survivability objection that has plagued catastrophic plate tectonics models. If the ocean heated uniformly to the temperatures required to dissipate the total tectonic heat, surface temperatures would exceed the tolerance of marine organisms. But the ocean does not heat uniformly. The Atlantic and Indian basins are lethally hot during the early event — but they contain no pre-existing ecosystem to destroy. They are newly opened rifts in what was previously dry continental crust. Nothing lives there because nothing lived there before the tear created them. The biology — marine and terrestrial — is in and around the Pacific, which is the remnant of the pre-event ocean. The Pacific stays cool because it receives no direct tectonic heat. It warms gradually to perhaps 20–25°C — warm, but well within the survival range of marine organisms.

The geometry that creates the heat also separates the heat from the biology. This is not a designed feature of the model. It is an intrinsic consequence of the cork-pop mechanism: the new basins are hot because they are new. The old basin is cool because it is old. The life is in the old basin because that is where it was before the event.

The thermal asymmetry also governs the atmosphere. Surface air flows from the cooler Pacific toward the thermal lows over the hot rift basins. At altitude, moisture-laden air rises over the furnaces and spreads outward — carrying evaporated water, volcanic aerosols, and sensible heat to high latitudes. This is a supercharged version of the Hadley circulation, driven not by the modern equator-to-pole gradient but by the far steeper gradient between the boiling rift basins and the cool Pacific.

The consequence is the ice age. Massive evaporation from the hot basins feeds extreme snowfall at the poles. Volcanic aerosols dim polar insolation, keeping the deposited snow from melting. The combination — extreme precipitation and reduced solar input at high latitudes — produces rapid ice accumulation on the timescale the master clock specifies. This is not a separate event requiring a separate explanation. It is an automatic consequence of the three-basin geometry. The warm rift basins produce the ice age naturally.

And the ice age, in turn, lowers sea levels — exposing continental shelves and opening land bridges between landmasses now separated by shallow seas. The dispersal highways open automatically as a consequence of the hot rift basins, and close automatically as those basins cool and the ice melts. The timing, duration, and extent of these land bridges are calculable from the basin cooling curves — which is the subject of the companion paper in this series.

The Climate Forcing

The catastrophe imposes two large radiative forcings on the global atmosphere. The first is volcanic aerosol cooling. The second is increased planetary albedo from sustained cloud cover over the boiling rift basins. Both are tied to the master clock — both peak with the active discharge phase and decay as the system relaxes toward modern conditions.

Volcanic forcing. During the active phase, the mid-ocean ridge system erupts continuously to produce new crust. The eruption rate is not a free parameter — it follows from the plate velocity. A fraction of this eruption is subaerial: continental arc volcanism at the Ring of Fire, plus flood basalt provinces along the separating margins. The subaerial fraction is the component that loads the atmosphere with sulfate aerosols. The effective volcanic forcing used here is approximately 60% of the original full-eruption-rate reference value of -10 W/m². This reduction reflects the subaerial fraction of total eruption (estimated at approximately 25–40% of total volume, scaled by the more explosive nature of catastrophic continental rifting), together with the rapid tropospheric washout that limits the residence time of tropospheric aerosols at high precipitation rates. The stratospheric component — above the precipitation regime — provides the persistent forcing. The result is approximately -6 W/m² at peak, decaying exponentially with plate velocity.

Cloud albedo forcing. The boiling rift basins drive near-continuous cloud cover over a large fraction of the planetary surface. As the basin area grows from year 0 to its full extent (approximately 28% of the ocean surface, or 20% of Earth's surface), the planetary albedo increases. The radiative effect of this increased albedo is estimated at approximately -6 W/m² at peak basin area — comparable to the volcanic forcing. This cloud deck has a built-in supply of condensation nuclei: the basin sulfur noted above — scrubbed from the transient margin jets and from the quenching basin surface — oxidizes to sulfate, and sulfate is among the most effective cloud condensation nuclei known. The boiling basins therefore seed and brighten the very cloud cover they raise, which gives the cloud term a concrete physical mechanism even though its magnitude remains a plausible estimate rather than a calibrated derivation. The cloud forcing decays as the rift basins transition from boiling to conductive cooling in Phase 3.

The combined forcing. The two forcings together reach approximately -9 W/m² during the peak phase (years 200–500), then decay. This is the input to the calibrated energy-balance-model response.

What These Conditions Demand
The forcings above matter less for what the model makes of them than for what they are: conditions whose atmospheric consequences are not in dispute. Set them in front of any working atmospheric scientist — a fifth of the ocean surface boiling, sustained aerosol dimming at high latitudes, an equator-to-pole temperature gradient far steeper than today's — and the first-order response follows with no model required. Evaporation on that scale must return as precipitation on that scale. Precipitation falling on aerosol-dimmed high latitudes accumulates as snow faster than it can melt. A steeper gradient drives stronger latitudinal contrast. Heavy rain, heavy polar snow, and a sharp pole-to-equator difference are not results this paper asks the reader to grant — they are what consensus atmospheric physics does with these inputs. The ice age is the over-determined consequence of the conditions, not a separate hypothesis bolted onto them.

What the conditions do not hand over is the magnitude. How much ice, accumulating how fast, distributed where, is a quantitative question that requires ice-sheet dynamics, ice-albedo feedback beyond what a simple model parameterizes, and a resolution of regional snow-versus-melt that the tools available here cannot supply. This paper therefore claims the existence and character of the ice age — forced, qualitative, and consistent with standard physics — and leaves its volume as an open quantity: physically real, but unquantified. The distinction is deliberate. The part atmospheric physics grants for free is claimed; the part that needs a model that the field does not yet have for this regime is not.

There is, however, one quantitative question the model can answer without resolving the spatial distribution: whether the water supply is even sufficient to build an ice age at all. This is a check on the budget, not a prediction of the outcome. The heat delivered to the basins during the active boiling phase evaporates a determinate mass of water — the heat must leave, and at a surface held at the boiling point water vapor carries most of it away — and that throughput is large: on the order of three ocean volumes cycled through the atmosphere during the boiling phase, set by the energy budget rather than by any tunable rate (Appendix F). Against that supply, the total ice the event must account for — the present polar sheets plus the water locked up at the glacial maximum, since the pre-event surface carried no ice — represents under two percent of the throughput retained as land ice rather than returned to the sea. The supply is not the bottleneck. A faithful spatial climate model would need to retain only about one to two percent of the evaporated water to produce ice on the scale observed, and that retention fraction — not the supply — is the quantity such a model could eventually pin down. The ice age that the conditions demand qualitatively is, on the arithmetic of the water budget, comfortably affordable.

A Check on the Global Response
None of the above rests on the energy-balance model — the qualitative outcome is forced by the physics whether or not any model is run. The model serves a narrower purpose: to confirm that the global-mean response to the implied forcing is bounded and sane, neither runaway nor negligible. The scenario's forcing — volcanic aerosol plus rift-basin cloud albedo, together of order −6 to −9 W/m² concentrated in the first few centuries — was run through a standard calibrated energy-balance model (climlab EBM_annual, A = 193, D = 0.7, calibrated to a modern reference GMT of 14.67°C); the volcanic forcing is taken as the central case and the cloud contribution as an estimated addition. The result is indicative only: the model produces a global-mean cooling of several degrees while the forcing is active, with temperatures relaxing toward the baseline as the forcing decays. That is the whole of what it establishes. It is not used to assign absolute temperatures, a latitudinal pattern, a recovery date, or ice volume — its tropical values in particular are artifacts of a simple model without convective limiting. Calibration and limitations are documented in Appendix B.

The Sea Level Budget

Four Mechanisms

Sea level change in this model is driven by four simultaneous mechanisms:

Basin deepening (dominant): As the continents separate, new ocean floor forms in the opening basins. Critically, this floor does not deepen immediately. The freshly emplaced material is a hot, buoyant, gas-charged melt body that rides high until it solidifies — which occurs near-batch at the latent-heat phase transition, approximately year 290 after the event (bracketed years 219–361 by the boiling-flux uncertainty). Only once solid lithosphere forms does the floor begin to deepen, drawing down sea level. Two physical processes drive that deepening, acting in the same direction and on the same timescale. First, continued separation of the continents keeps opening new basin volume — a geometric effect that depends only on plate displacement, not on any thermal assumption. Second, the newly solidified floor cools from the solidus toward the modern geotherm and contracts, lowering the floor further. The two contributions are comparable in size; neither alone is the whole story. Their magnitudes and timing are derived in Appendix D. Together they drop the floor by several hundred meters, with most of the drop delivered in the first few centuries after solidification as both the spreading and the boiling-driven cooling are most rapid.

Ice accumulation (acknowledged, not quantified): Water locked in continental ice sheets is removed from the liquid ocean. The catastrophe drives high-latitude cooling sufficient to initiate ice accumulation (see climate model results above), but the total ice volume produced is not modeled in this paper. Ice accumulation is therefore omitted from the quantitative sea level budget below; its contribution is additive on top of the basin-driven drop.

Thermal expansion (opposing): The warm ocean — particularly the deep ocean, which warms substantially during the active discharge phase as heat is delivered from the rift basins — occupies more volume than cold ocean. This partially offsets the other mechanisms and is significant during the first several centuries before fading as the ocean cools.

Isostatic adjustment (opposing): As water redistributes from the ocean surface into new basin volume and continental ice, the crust responds elastically. Ocean floors rebound slightly, continental shelves subside, and new oceanic crust cools and sinks. The standard Airy isostatic correction is approximately 30% of the gross sea level change, reducing the effective drop experienced at the continental margins.

Because the basin floor cannot deepen before it solidifies, this paper makes no sea level prediction before lithosphere forms (approximately year 290, bracketed 219–361). Before that point, the floor is a transient melt body whose elevation is not constrainable from the available observables. The first defensible sea level point is at solidification; all bridge timing below is stated from that anchor forward. A brief early redistribution of water — the squeezed Pacific transgressing as the new basins are still shallow — is physically expected in the pre-solidification window but is not quantified here.

The combined budget, with the subsidence clock anchored at solidification (year 290) and ice contribution omitted as discussed above:

Subsidence clock anchored at solidification (year ~290). The boiling-flux crossover bracket (solidification at years 219–361) shifts the opening dates by approximately ±80 years relative to the midpoint, slightly more for the deeper sills; see Appendix D. The displacement term is geometric (new crust volume opening new basin volume) and carries no thermal-strain uncertainty. The thermal contraction term is computed at the free-shrinkage strain mode (α/3 ≈ 9 × 10⁻⁶ K⁻¹), which the basin geometry supports: at solidification the basin is already roughly 2,400 km wide on each flank and still widening, so the newly solidified floor remains laterally unconfined and contracts in all three dimensions rather than vertically only. The two terms are comparable in magnitude; see Appendix D for the derivation and the strain-mode justification.

This is a fundamentally different framework from conventional ice-age sea level models, which attribute the entire drop to ice accumulation. In this model, the basins deepen — through continued spreading and through cooling-contraction of the new floor — and the ocean follows the floor down. Ice accumulation is a real and additive contribution on top of this drop, but is not quantified here. The bridge timing analysis that follows uses the basin-deepening budget as a conservative case — any ice contribution would deepen the sea level and open the bridges earlier. The froth collapse of the de-gassing melt body as it solidifies is a further additive contribution to the early drop, acknowledged but not quantified.

The conclusion is robust across the full parameter range. Even at the conservative end — thermal contraction at the low expansion coefficient and the smaller mean-column cooling, displacement at the shallow basin-depth assumption — the net drop clears the deepest intercontinental sill (Red Sea / Arabia, ≈ 130 m) within the first millennium after solidification. At the central estimate it clears by roughly year 600. The deep sills clear on the displacement term alone, and separately on the thermal term alone, at the central estimate; the bridge-opening conclusion therefore does not depend on the strain-mode assumption that is the softest part of the thermal calculation.

The sensitivity of these results to the key uncertain parameters — the thermal contraction magnitude and the solidification timing — is analyzed in Appendix D. The conclusion is robust: across the plausible range, all major land bridges open within the first few centuries to less than a millennium after solidification, with substantial margin.

Figure 1 shows the sea level budget over time, anchored at solidification (year 290). Continued basin opening and thermal contraction of the new lithosphere together drive the gross drop, opposed by the isostatic correction (gray). The net drop (green, with uncertainty band) crosses each bridge's sill depth within the first few centuries after solidification.

When the Bridges Open

The sea level budget translates directly into land bridge timing. Each bridge opens when the net sea level drop exceeds the sill depth of the strait. The shallowest sills clear first, the deepest last, as the floor continues to deepen through the first few centuries after solidification.

Opening windows span the full uncertainty: the boiling-flux crossover bracket (solidification at years 219–361, midpoint 290) combined with the parameter range in the two-term budget (thermal expansion coefficient, mean-column cooling, and mechanical basin depth). The early edge of each window corresponds to fast solidification and the more generous parameters; the late edge to slow solidification and the conservative parameters. At the conservative extreme the deepest sills open slightly later still — within the first millennium — but every major bridge opens. See Appendix D for the derivation and the sensitivity analysis.

Every major intercontinental bridge opens within roughly the first few centuries (upper bound of a millennium) after lithosphere forms — the shallow straits within about a century of solidification, the deepest within a few centuries. Across the full uncertainty range the openings fall between roughly year 270 and year 860 from the event, with the shallow bridges leading and the deep bridges trailing. The corridors then remain open through a long connectivity window before closing.

The closing is treated separately and with less precision than the opening, for a reason grounded in the physics. The opening is driven by basin deepening — continued spreading and thermal contraction — both of which are anchored on present-day observables and are essentially complete within the first few centuries. The closing is driven by the slower return of water to the deepened basins: the transfer of water and sediment off the continents and into the oceans, the mechanistic subject of the companion Deposition series, together with the redistribution of crustal load as the continents unload and the basins fill. These processes raise relative sea level at the sills and re-drown the corridors. Their timing and magnitude are not quantifiable from the observables used in this paper, so this paper does not assign closure dates. What is certain is the outcome: the corridors are closed today. Closure therefore happened — the only open question is its precise schedule, which the present model does not predict. The dispersal window is best characterized as opening within the first few centuries after solidification and remaining open for centuries thereafter, closing gradually as the continents shed their water and sediment into the basins.

The Corridors

Climate Shapes the Highway

A land bridge is not a highway unless it has food. The climate profile at each corridor determines which animals can use it, because the climate determines what grows there. Because every corridor is ultimately fed by the same warm-ocean moisture source and volcanic aerosol cooling, the primary differences among them arise from latitude, distance from the coast, and local topography.

Seven major corridors radiate from the landing zone in the Armenian Highlands: the Eurasian Highland trunk (35–50°N), Beringia (60–70°N), the Sunda Shelf (0–10°S), the Sahul Shelf (0–40°S), the Arabian/Red Sea corridor (15–30°N), Doggerland (50–55°N), and the Bab el-Mandeb crossing. Each has a distinct climate character — temperature, precipitation, and coastal-to-inland moisture gradient — that acts as an environmental filter on the animals passing through.

The Eurasian Highland (35–50°N) is the primary trunk. Every animal starts here. Warm temperate woodland — 14–23°C, 900–2,100 mm/yr precipitation — habitable in all directions from day one. No filtering. This is the launching pad.

Beringia (60–70°N) is a cold filter. Tundra shrubland — temperatures below freezing year-round, 200–1,100 mm/yr. Passable but harsh. This corridor selects for cold-adapted megafauna: mammoth, bison, wolf, bear. Tropical species are excluded entirely.

The Sunda Shelf (0–10°S) is a tropical superhighway. Dense rainforest — 26–31°C, 2,600–4,500 mm/yr. Minimal filtering. Everything that reaches this corridor gets through. The 2.5 million km² of exposed shelf at peak lowstand is the largest single expanse of newly available tropical habitat on the planet.

The Sahul Shelf connects to Australia and New Guinea. Tropical at the entry (New Guinea), grading to warm temperate (Tasmania). The coastal corridor is dense rainforest; the interior opens to seasonal woodland. A long-lived bridge with moderate filtering — forest-adapted species travel the coast, grassland species follow later as the interior dries.

The Arabian corridor (15–30°N) is the Africa filter — and the sharpest one. Coastal precipitation of 1,100–2,500 mm/yr drops to 100–600 mm/yr within a few hundred kilometers inland. A narrow humid coastal strip with desert immediately behind it. This corridor selects for large, mobile species capable of traversing semi-arid gaps: elephants, big cats, bovids. Small forest-dependent species requiring continuous dense cover are excluded. This filtering explains why Africa's founding fauna is dominated by large mammals rather than small forest specialists.

Doggerland (50–55°N) extends the Eurasian trunk westward, connecting Britain to continental Europe. Cool temperate throughout. Minimal filtering.

The Bab el-Mandeb crossing at the southern end of the Red Sea provides a second, narrower connection to Africa. Climate and filtering character are similar to the Arabian corridor — a thin productive coastal strip with arid interior — but the crossing itself is shorter and more direct.

The precipitation gradient — not the temperature gradient — is the dominant control on corridor character. Coastal zones typically receive 2–5 times the annual precipitation of interior zones at the same latitude, creating lush coastal highways bordered by progressively drier woodlands and steppe. The moisture comes from the warm ocean; the gradient comes from distance. Animals following coastal corridors walk through lush habitat. Those attempting interior crossings face progressively drier conditions.

The extreme precipitation also rebuilds the freshwater system that animals require for survival. Fresh water is less dense than salt water and floats. With precipitation running at many times the modern rate — driven by the extreme evaporation from the hot Atlantic and Indian rift basins (Proposition 7) — freshwater lenses form on the surface of any standing water within days. Highland streams and springs run fresh almost immediately; rain hits exposed rock and flows downhill without ever contacting salt. Lakes refill with fresh water as rainfall overwhelms residual salinity. Rivers carve new channels through soft post-catastrophe sediment, fed entirely by fresh precipitation.

The full corridor climate profiles, developed independently and validated against the calibrated energy balance model, are presented in Appendix E.

The Table Is Set

Vegetation Leads the Animals

A corridor with the right climate is still impassable if nothing grows there. The critical question is whether vegetation establishes fast enough on post-catastrophe terrain to support animal populations within the bridge windows.

The published literature on volcanic succession answers this unambiguously: yes.

Krakatoa, sterilized to bare rock in 1883, supported dense grassland within three years, woodland within fifty, and mature tropical forest within a century. Mount St. Helens, devastated in 1980, showed pioneer vegetation within months — fireweed, grasses, and lupines — with visible forest recovery within fifteen years. These are cases of primary succession, starting from nothing: no surviving roots, no seed bank, no soil biology. Seeds arrived by wind and water from distant sources across open ocean or devastated terrain.

The post-catastrophe landscape in this model does not start from nothing. The brief, dynamic inundation described in the first paper (Proposition 3) leaves surviving root systems, seed banks, and soil microbiomes. This is secondary succession, which the ecological literature consistently shows is 5–10 times faster than primary succession.

The Genesis text provides a direct data point confirming this timeline. At day 272 — approximately seven months after the onset and months after the highlands first emerged — the dove returns carrying a freshly plucked olive leaf. As established in the first paper (Proposition 6), olive trees survive brief saltwater inundation and resprout vigorously on volcanic ash soil under heavy rainfall. The olive leaf is not a miracle. It is a field measurement confirming that secondary succession on the highlands is already months old — consistent with the published recovery rates from Krakatoa and Mount St. Helens, and likely faster given the surviving root systems and extreme precipitation.

Three additional factors accelerate the process beyond what modern analogs demonstrate. First, precipitation runs at 2–4 times modern rates, accelerating every stage of the succession cycle — salt washout, germination, nutrient cycling, and growth. Second, continuous volcanic ash deposition provides an ongoing supply of mineral nutrients. Published research shows that volcanic ash at concentrations above 3% in soil triples plant biomass and restructures the soil microbiome to promote plant-growth-promoting bacteria — the soil ecosystem, in the words of one research team, "flips a switch." Third, warm year-round temperatures in the tropical and subtropical corridors eliminate the cold-season growth limitation that slows succession at higher latitudes.

The published data support specific timelines. At Krakatoa (primary succession on sterilized rock), grassland dominated within 14 years and closed-canopy tropical forest developed within a century. At Mount St. Helens (mixed primary and secondary succession), pioneer species appeared within months in areas with surviving root systems, plant cover reached 38% within 14 years and 66% within 20 years, and visible forest recovery occurred within 15 years. Under the more favorable conditions in this model — secondary succession with surviving root systems, 2–4× modern precipitation, and continuous volcanic ash fertilization — succession timelines are estimated at 5–10× faster than the primary succession observed at these sites.

Scaling observed secondary succession rates by the three accelerating factors yields the following corridor-by-corridor estimates:

Vegetation timelines scaled from Krakatoa and Mount St. Helens secondary succession data, adjusted for 2–4× precipitation, continuous volcanic ash fertilization, and surviving root systems (5–10× acceleration over primary succession). Bridge timing from the thermal-contraction subsidence model (Appendix D), anchored at solidification (year 290).

The table is set before the guests arrive. Because the bridges open later — after lithosphere forms and the basins contract — the vegetation has even more time to establish. In every corridor, the animals walk into an ecosystem that is already growing, already producing food, and getting more productive every year. The delay in bridge opening, far from being a problem, widens the margin by which the food supply precedes the travelers.

Summary

The waters parted early.

The new ocean basins form solid lithosphere at the latent-heat phase transition, approximately year 290 after the catastrophe. Only then does the floor begin to cool, contract, and subside, drawing sea level down. Within the first few centuries to first millennium of solidification — by approximately year 600 at the central estimate — the net drop clears every major intercontinental sill, and all the land bridges are open. The deepening that opens them comes from two comparable sources: continued separation of the continents opening new basin volume, and cooling-contraction of the newly solidified floor. The corridors remain open for centuries, then close gradually as the continents shed their water and sediment into the basins — a slower process whose schedule this paper does not predict, bounded by the certainty that the corridors are closed today. The opening timing carries a bracket of roughly +50 to −75 years from the uncertainty in the solidification date.

These bridges are not barren rock. They are corridors shaped by a distinct climate — warm tropics driving massive evaporation, cold high latitudes building ice, and a steep coastal-to-inland precipitation gradient creating lush coastal highways flanked by drier interiors. Each corridor's climate acts as an environmental filter, admitting certain animals and excluding others.

The vegetation is already there when the bridges open. Post-catastrophe succession, accelerated by extreme rainfall, volcanic ash fertilization, and surviving root systems, produces functional ecosystems in years to decades — faster than the bridges form.

The system is a single machine. One equation — the plate velocity as a function of time — drives everything: the ocean heating, the basin deepening, the mountain building, the volcanic forcing, the ice accumulation, the sea level drop, and the opening of the corridors. Two primary observational constraints plus the narrative's recorded phase transition drive five major outputs.

The animals exit the ark into a greening continent. The highways open within the first few centuries after the new sea floor solidifies. The vegetation is waiting for them. The question that remains — which animals walk which corridors, how fast they spread, and why each continent ends up with the fauna it has — is the subject of the final paper in this series.

What This Paper Does Not Claim

This paper does not claim to quantify ice volume or rate of ice accumulation. The energy balance model produces a temperature response to a calibrated forcing; it does not include ice sheet dynamics, ice-albedo positive feedback beyond the EBM's parameterization, or any mechanism for tracking ice mass. The conditions for ice accumulation — sustained polar cooling and enhanced moisture supply — are produced by the model. The resulting ice volume is not. A full ice sheet model would be required.

The energy balance model is used solely as an indicative consistency check that the implied forcing yields a sane climate response. It does not predict absolute temperatures (its tropical values are artifacts of a simple EBM without convective limiting), the latitudinal pattern of cooling, the timing of return to modern climate (set by the model's heat capacity, not the scenario), or ice volume.

This paper does not claim to model the spatial distribution of ocean surface temperature. The three-basin thermal architecture established in the Trigger Standalone — hot Atlantic and Indian rift basins, cool Pacific remnant — is a key feature of the post-catastrophe ocean, but is not simulated here. The downstream analysis (sea level budget, bridge timing) does not depend on basin-resolved SST. Readers interested in the basin-resolved heat budget are referred to Appendix F of the Trigger Standalone.

This paper does not claim that the cloud albedo forcing is calibrated. The magnitude (-6 W/m² peak) is a plausible estimate of the radiative effect of near-continuous cloud cover over the boiling rift basins. It is presented as a component of the climate forcing because it is physically expected, but its exact magnitude requires a cloud-resolving model that is beyond the scope of this paper. The qualitative conclusion — that the catastrophe drives sustained high-latitude cooling sufficient to initiate ice accumulation — is robust to substantial variation in the cloud forcing magnitude.

This paper does not claim that the quantitative results are precise. The sea level budget and corridor climate profiles are order-of-magnitude estimates derived from calibrated but simplified models. A full general circulation model would refine these numbers — but the extreme and rapidly varying forcing conditions of the post-catastrophe environment sit outside the calibration range of standard GCMs, making a reduced-complexity approach both necessary and more appropriate at this stage.

This paper does not claim a precise sea level curve or precise bridge-opening dates. The subsidence is derived from two terms — continued geometric basin opening and thermal contraction of the new lithosphere — anchored on the plate velocity, the modern floor depth, and the modern heat flux. The thermal term carries uncertainty from the expansion coefficient and the strain mode (a factor of up to three between the unconfined and confined limits; the conservative unconfined value is adopted), and the timing carries a bracket of roughly +50 to −75 years from the solidification date (the boiling-flux crossover, years 219–361). The conclusion that all major bridges open within the first few centuries after solidification is robust across this entire range — the deep sills clear on the displacement term alone at the central estimate — but the exact dates are not claimed.

This paper does not claim that the vegetation succession timeline is precisely calibrated to the post-catastrophe conditions. The modern volcanic analogs (Krakatoa, Mount St. Helens, Surtsey) provide directional evidence and order-of-magnitude timing, but no modern event matches the scale, precipitation intensity, or biological starting conditions of the model. The claim is that vegetation establishes faster in this model than in the observed analogs, not that the exact timeline is known.

This paper does not claim that the corridor climate profiles represent exact conditions at any specific location. They are latitude-band averages with coastal-inland gradients, derived from an energy balance model and independently validated. Local topography, ocean currents, and regional weather patterns would modify these profiles substantially. The claim is that the corridors are habitable, not that their precise temperature and precipitation at any given point are known.

This paper does not address the biological response — which animals use which corridors, how fast they spread, or why each continent's fauna looks the way it does. That is the subject of the companion paper.

This paper does not claim that the model is derived purely from physics independent of the text. The Genesis narrative supplies the timing of the mabbul-to-mayim transition (day 40), which is used as the phase boundary in the two-phase velocity model. The narrative is treated as an engineering specification — the physics follows from the constraints it provides. This is stated explicitly and should be evaluated as an "if...then" proposition: if the narrative is accurate, then these are the physical consequences.

Appendices

Appendix A: Two-Phase Plate Velocity Model

The day-40 phase transition and τ_A = 5 days are taken directly from the narrative's shift from mabbul to mayim; these anchors, together with the two observational constraints, yield a unique solution for v_peak and τ_B.

The plate velocity follows a two-phase exponential decay:

Phase A (t ≤ 40 days): v(t) = v_peak × exp(-t/τ_A)

• v_peak = 30,652 km/yr (0.97 m/s)

• τ_A = 5 days (set by the narrative phase transition)

• Displacement: 419 km (8.4%)

Phase B (t > 40 days): v(t) = v_trans × exp(-(t - t_trans)/τ_B)

• v_trans = 10.28 km/yr (continuous with Phase A at day 40)

• τ_B = 445 years

• Displacement: 4,581 km (91.6%)

Constraints:

• Total displacement = 5,000 km (observed continental separation)

• v(5,450 years) = 5 cm/yr (modern GPS measurement)

The solution for v_peak and τ_B is unique once the phase transition day and τ_A are fixed by the narrative. Sensitivity analysis shows that τ_B is largely insensitive to the choice of τ_A: across τ_A = 5 to 10 days, τ_B varies only from 442 to 445 years. Phase B — which drives all the quantitative results in this paper — is robust to this uncertainty.

Appendix B: Climate Model Calibration and Catastrophist Run

This appendix documents the climate model setup, calibration, and limitations. The Python script reproducing all temperature results in this paper is available in the supplementary materials.

Model. The energy balance model used is climlab's EBM_annual (Rose, 2018), a one-dimensional annual-mean latitude-resolved energy balance model with diffusive heat transport, ice-albedo feedback, and a parameterized longwave radiation scheme (OLR = A + B·T). The model has 36 latitude bands from 87.5°S to 87.5°N.

Calibration to modern climate. The model was calibrated to reproduce modern global mean temperature by tuning the OLR intercept parameter A:

The calibrated baseline produces a modern global mean temperature of 14.67°C, against an observed value of approximately 14.7°C.

Sensitivity calibration. The model's equilibrium climate sensitivity is set by B = 2.0 W/m²/K, giving λ = 0.5 K/(W/m²). A sustained +4 W/m² forcing produces a 1.63°C equilibrium global cooling after 100 model years. This sensitivity is in line with central estimates from IPCC AR6 (equilibrium climate sensitivity of approximately 3°C for a doubling of CO₂, which corresponds to a forcing of approximately 3.7 W/m²; the model gives 1.85°C, on the low end of the IPCC range).

Limitation: transient volcanic response. The annual-mean EBM equilibrates each timestep and therefore cannot reproduce the transient peak cooling observed after individual volcanic eruptions such as Pinatubo (1991) and Tambora (1815), which have radiative forcing durations of months. The published transient response — approximately 0.5°C peak cooling after Pinatubo's -4 W/m² peak forcing — reflects ocean thermal inertia and the brief duration of the forcing, neither of which the annual EBM captures. For the catastrophist run, the forcings are sustained for centuries — well above the annual model's resolution — so the equilibrium response is the correct measure. The equilibrium sensitivity, not the transient response, is the calibration anchor.

Catastrophist forcing. Two time-varying forcings were applied:

Volcanic. F_volcanic(t) = -6.0 × v(t) / v(0), where v(t) is the plate velocity from the Trigger Standalone (scaled velocity profile, τ₁ = 500 yr). Peak: -6 W/m² at year 0; decays exponentially with plate velocity.

Cloud albedo. F_cloud(t) = -6.0 × (f_earth(t) / 0.20), where f_earth(t) is the fraction of Earth's surface covered by the rift basins at time t. Active during Phase 1–2 only (years 0 to crossover + 400). Peak: approximately -6 W/m² at full basin area.

The forcings were applied additively to the OLR intercept: A_eff(t) = A + |F_volcanic(t) + F_cloud(t)|.

Reduced volcanic forcing rationale. The -10 W/m² figure in earlier drafts of this paper assumed full eruption rate at 64× modern with stratospheric injection. In the cork-pop mechanism, the majority of catastrophic eruption is submarine ridge volcanism. The subaerial fraction (continental arc volcanism and flood basalt provinces) loads the upper atmosphere with sulfate aerosols and is the basis for the stratospheric forcing used here. The submarine fraction is not radiatively inert — magma quenching against the boiling basin surface is a genuine sulfur source — but that sulfur is scrubbed into the brine or rained out of the lower atmosphere rather than reaching the stratosphere, so it is routed to the cloud-albedo term (Appendix C) rather than to the stratospheric forcing computed here. With approximately 60% of the original reference value attributable to subaerial sources, the effective forcing reduces to approximately -6 W/m². This is an estimate, not a calibrated derivation.

What this model does not produce. The model produces temperature response to radiative forcing. It does not produce ice sheet volume or accumulation rate (no ice sheet dynamics module), ocean SST distribution (no ocean basin geometry), precipitation patterns (no atmospheric moisture transport), or regional climate (zonal annual mean only). The sea level budget in this paper uses the basin deepening calculation (pure geometry, no climate model required), thermal expansion (computed from the heat budget in Appendix F of the Trigger Standalone), and isostatic adjustment (Airy correction at 30%). The ice contribution to sea level is acknowledged as physically real but not quantified.

Appendix C: Volcanic Forcing Derivation

The volcanic forcing applied in the catastrophist run is derived from three components: the eruption rate (set by plate velocity), the subaerial fraction of total eruption (the radiatively active component), and the washout physics that limits tropospheric aerosol residence time at high precipitation. A fourth quantity — the sulfur emitted by submarine basin emplacement — is treated here as well, but it is routed to the cloud-albedo term in the main text rather than to the stratospheric forcing derived below.

Eruption rate. Plate velocity determines magma production at the spreading ridges, which in turn sets the SO₂ flux. At peak Phase B velocity (≈11 km/yr in the scaled profile from the Trigger Standalone), the integrated mid-ocean ridge eruption rate is approximately 64 times the modern global volcanic output. This is not a free parameter; it follows from the plate velocity that is in turn constrained by the master clock.

Subaerial fraction. The subaerial fraction — continental arc volcanism at the Ring of Fire and flood basalt provinces along separating margins — is the component that loads the upper atmosphere with sulfate aerosols and is the basis for the stratospheric forcing derived here. Modern ratio is approximately 25% subaerial / 75% submarine by volume. Under catastrophic conditions with explosive continental rifting, the subaerial fraction may be modestly higher (estimated 25–40%). The radiatively active eruption rate is therefore approximately 25–40% × 64× ≈ 16–26× modern. The submarine remainder is not radiatively inert — its disposition is treated under "Submarine basin sulfur" below — but it does not contribute to the stratospheric forcing computed in this appendix.

Washout physics. The Seinfeld-Pandis aerosol scavenging coefficient λ = a × R^b (a = 5 × 10⁻⁵ s⁻¹, b = 0.7, R = precipitation rate in mm/hr) gives tropospheric aerosol residence times of approximately 0.3–0.4 days at the extreme post-catastrophe precipitation rates (12–15 mm/day). Tropospheric aerosols are scrubbed in hours; only the stratospheric fraction provides persistent radiative forcing. The stratospheric injection fraction from explosive subaerial eruption is approximately 10–30%.

Submarine basin sulfur. The submarine fraction is conventionally dismissed as radiatively negligible, on the model of deep passive ridge volcanism: at mid-ocean-ridge depths the hydrostatic pressure suppresses volatile exsolution and any sulfur stays dissolved in the melt or the water column. That regime does not apply to the rift-basin emplacement in this model, which occurs at or near the surface against boiling seawater. Two sub-regimes operate, with opposite behavior. At a freshly opening margin, magma is driven up under pressure and makes direct contact with liquid water before a stable insulating vapor film can form; this is the explosive molten-fuel-coolant regime — rapid repeated flashing, fine fragmentation, and sulfur thrown clear of the melt before the surrounding brine can capture it. Once a steady vapor film establishes (the Leidenfrost regime), the film insulates the magma, the interaction quiets, and the boiling brine scrubs most of the exsolved SO₂ before it escapes. The violent regime is brief at any single point, but the margin advances continuously for centuries as the continents separate, so the explosive front is perpetually renewed along thousands of kilometers of opening rift; its intensity scales with plate velocity in the same way the ridge eruption rate does. The fate of this sulfur differs from the subaerial fraction: the plumes are Surtseyan, topping out in the upper troposphere (~9 km) rather than reaching the stratosphere, and what does reach the lower atmosphere is rained out within a day by the washout physics above. It therefore contributes essentially nothing to the persistent stratospheric forcing. Its significance is indirect — as sulfate, it is among the most effective cloud condensation nuclei known, and it seeds and brightens the basin cloud deck. It is accounted for in the cloud-albedo term in the main text, not here, and no part of it is added to the −6 W/m² figure below.

Net forcing. Combining the subaerial fraction (≈ 30% central estimate), the stratospheric injection fraction (≈ 15% central estimate), and the logarithmic saturation of radiative forcing at high aerosol optical depth (F ≈ -25 × ln(1 + AOD)), the effective steady-state forcing is approximately -6 W/m² at peak velocity.

Time dependence. The forcing decays exponentially with plate velocity: F_volcanic(t) = -6.0 × v(t) / v(0). This produces the volcanic-forcing values used in the main text.

Sensitivity. Across the plausible range of subaerial fractions (25–40%) and stratospheric injection fractions (10–30%), the peak forcing ranges from approximately -4 to -8 W/m². The qualitative conclusion — sustained high-latitude cooling sufficient to initiate ice accumulation — holds across this range. The cloud albedo contribution discussed in the main text (estimated -6 W/m² peak) is independent of this volcanic forcing and provides additional cooling whose magnitude is similarly bracketed but less well constrained; the submarine basin sulfur described above strengthens the physical basis for that cloud term but does not change its estimated magnitude.

Appendix D: Basin Subsidence — Two-Term Deepening Model

The sea level drop in this model is driven by the deepening of the new ocean basins after their floors solidify. Two physical processes contribute, comparable in magnitude and acting on the same timescale: continued geometric opening of basin volume as the continents separate, and thermal contraction of the solidified floor as it cools. This appendix derives both, anchored on present-day observables, without invoking the conventional age-depth (√age) relation — which is calibrated in millions of years and would import the deep-time assumption this framework rejects.

Why not the √age curve. The conventional ocean-floor subsidence relation, d(t) = d_ridge + C·√(age), describes incremental crust accreted strip-by-strip at a spreading ridge, each strip cooling from its own formation moment. The new basins in this model do not form that way. The floor is emplaced as a single hot, gas-charged melt body that loses latent heat through the boiling discharge and then solidifies near-batch at the phase transition. The relevant physics is bulk cooling of a solidified volume plus continued geometric basin opening, not strip accretion. The √age coefficient and its Myr calibration do not apply.

Term 1 — Displacement (geometric). As the continents continue to separate after the floor solidifies, new basin volume opens at a rate set by the plate velocity. This is a purely geometric effect: new crust volume equals new basin volume, and the ocean surface falls as that volume opens beneath it. Scaling from the full basin-geometry model (gross drop of approximately 0.075 m per kilometer of post-solidification displacement at the 0.8 km reference mechanical depth), and integrating the velocity profile from solidification (year 290) onward, the displacement-driven gross drop reaches approximately 175 m by year 1000 and approximately 195 m by year 2000. This term carries no thermal or strain assumptions; its only inputs are the plate velocity (the master clock) and the mechanical basin depth (bracketed 0.5–1.0 km).

Term 2 — Thermal contraction. Once the column solidifies (near-batch, at the latent-heat phase transition, approximately year 290), it cools from the solidus toward the modern geotherm. The vertical subsidence is the thermal contraction of the column:

Δd = α_eff · ΔT̄ · H

where ΔT̄ is the drop in mean column temperature from solidification to today (solidus ≈ 1100°C to modern mean column temperature ≈ 650°C, giving ΔT̄ ≈ 450 K; varying the modern mean between 550–700°C changes this term by roughly ±15–20%), H is the lithospheric column thickness (≈ 39 km), and α_eff is the effective vertical thermal expansion coefficient.

The strain-mode choice (α_eff). The value of α_eff depends on how the cooling column is mechanically constrained. A laterally confined column directs all its thermal contraction into vertical subsidence and takes the full volumetric coefficient (α_vol ≈ 2.7 × 10⁻⁵ K⁻¹). A laterally unconfined column shrinks in all three dimensions and takes the linear coefficient (α_vol / 3 ≈ 9 × 10⁻⁶ K⁻¹). The basin geometry determines which applies. At solidification (year 290) the basin is already approximately 2,400 km wide on each flank of the rift and is still widening as the continents separate; the newly solidified floor is bordered by mush and open water, not by rigid confining lithosphere, and the continental margins are receding. The floor is therefore laterally unconfined for the prediction-relevant interval, and the linear coefficient (α_eff = α_vol / 3) is adopted as the central case. This is the conservative choice — it yields the smaller thermal drop. The confined limit (full α_vol) would roughly triple this term; it is noted as an upper bound but not adopted, because the geometry does not support it during the window in which the bridges open.

At the central case (α_eff = α_vol / 3, ΔT̄ = 450 K, H = 39 km), the thermal contraction yields a total subsidence of approximately 160 m (range roughly 120–195 m across the ΔT̄ uncertainty). The endpoints are pinned by observables: the modern floor depth and the modern residual heat flux (≈ 60 mW/m², used in the foundational standalone's Appendix F) together fix the present thermal state, and the solidus fixes the starting state.

The timing. Both terms are front-loaded. The displacement term follows the decaying plate velocity — fastest early. The thermal term tracks the cooling, whose rate is set by the boiling discharge P_released(t) from the foundational standalone — also front-loaded. Consequently most of the combined deepening occurs in the first few centuries after solidification:

Net drop at the margins. The gross deepening is reduced at the continental margins by the isostatic correction (standard Airy correction, ≈ 30% of gross). The net drop available to clear the bridge sills is therefore approximately 0.70 × gross, reaching roughly 250 m at completion — comfortably more than the deepest sill (Red Sea / Arabia, ≈ 130 m).

Robustness. The two terms are comparable in magnitude and act together, which makes the opening conclusion robust. At the central estimate the deepest sill clears by approximately year 600. At the conservative end of every parameter (thermal at the low ΔT̄, displacement at the 0.5 km mechanical depth), the deepest sill still clears within the first millennium. At the central estimate the deep sills clear on the displacement term alone, and separately on the thermal term alone. The bridge-opening conclusion therefore does not depend on the strain-mode choice that is the softest part of the thermal calculation — the displacement term, which carries no strain uncertainty, is by itself sufficient to clear the sills at the central estimate.

Crossover-case bracket. The solidification date depends on the boiling heat flux, which is bracketed at years 219 (20 kW/m²) and 361 (10 kW/m²); the midpoint used throughout the main text is year 290. The two bracketing cases shift the bridge-opening dates by roughly +75 to −75 years relative to the midpoint. The qualitative conclusion — all major bridges open within the first few centuries to first millennium after solidification — is robust across the bracket.

Additional unquantified contribution. As the gas-charged melt body solidifies, it also collapses from any elevated "froth" stand (vesiculation and active convection bulk up the agitated column; this collapses as the system degasses and settles). This adds to the early drop. Its magnitude depends on volatile content and emplacement conditions that are not constrainable from the available observables, so it is acknowledged but not quantified. It acts in the same direction as the other two terms (additional early drop).

Closure. This paper predicts when the bridges open but not when they close. The opening mechanisms are front-loaded and largely complete within a few centuries: the displacement term follows the rapidly decaying plate velocity, and the thermal contraction follows the front-loaded boiling discharge. The closing mechanisms, by contrast, are cumulative and ongoing over much longer timescales — the transfer of water and sediment from the continents to the oceans (the mechanistic subject of the companion Deposition series), together with the redistribution of crustal load as the continents unload and the basins fill, which raises relative sea level at the sills. Because the opening is fast and the closing is slow and cumulative, the corridors stand open for a long window after the deepening completes. The closing processes' timing and magnitude are not constrainable from the observables used here, so no closure dates are assigned. The outcome, however, is fixed by direct observation: the corridors are closed today. Closure therefore occurred; only its schedule is unpredicted. This asymmetry — a well-constrained opening and an observationally-bounded but unquantified closing — is intrinsic to the available evidence and is stated rather than papered over.

Methodological boundary. No sea level prediction is made before solidification. Before the phase transition, the floor is a transient melt body whose elevation is not constrainable. The first defensible point is at solidification (year 290), and all timing is stated from that anchor.

Appendix E: Corridor Climate Profiles

Full latitude-by-time climate tables with coastal-inland precipitation gradients for all seven corridors (Eurasian Highland, Beringia, Sunda, Sahul, Arabian, Bab el-Mandeb, Doggerland) are available in the supplementary materials. These profiles were derived independently of the energy balance model. The two are cross-checked only at the qualitative level — the corridor character (hot tropics, cold poles, habitable mid-latitudes) agrees between them — and the absolute per-latitude temperatures are not used to validate either. Where they differ, they differ in the expected direction: the independent assessment is several degrees cooler at the equator and warmer at the mid-latitudes than the bare EBM, consistent with the EBM's known tendency to run hot in the tropics without convective limiting. The two agree most closely at high latitude (≈75°N), where ice formation is the critical process. Consistent with the main text, the energy balance model is not used here to set absolute corridor temperatures or the latitudinal pattern; it serves only as a qualitative consistency check.

Appendix F: Evaporative Supply for Ice Accumulation

This appendix tests one question: does the boiling-basin mechanism cycle enough water through the atmosphere to build the observed ice, and what fraction of that cycling water would have to fall and persist as high-latitude snow to do it? It is a supply calculation, not an ice prediction. It does not model where snow falls or whether it persists — those depend on the spatial temperature field, which the tools here do not resolve. It establishes only the size of the water budget the climate has to work with.

The water comes from the boiling phase, not the whole event The heat budget in "What Broke the Foundations?" (Appendix F) delivers energy to the ocean in three phases. Only the first two — the charging and discharge phases, when the basins boil across their surface — drive the violent evaporation that loads the atmosphere. The third phase is a conductive tail through a sealed plate that delivers the residual heat slowly to the present day; it raises no steam and lays no ice, and it is excluded here. The cutoff is therefore not a chosen window but a physical transition: evaporation for ice purposes ends when the basin surface drops below boiling (the Phase 2→3 transition), which the heat-budget model places at year 457 in the high-flux case and year 823 in the low-flux case.

The energy delivered to the ocean through the end of boiling, read directly from the heat-budget tables, is 11.9 × 10²⁷ J (20 kW/m² case) to 14.4 × 10²⁷ J (10 kW/m² case). The two flux cases are the bracket throughout; no value between them is assumed.

Most of that energy leaves as steam The basin is held at the boiling point and refilled laterally from its open ends as fast as it boils off, so it behaves as a pot at a continuous boil: it cannot bank sensible heat above 100 °C, and there is no stable cool layer to carry heat away unevaporated. The competing loss channels are therefore bounded and small — longwave radiation from the 373 K surface (~1.1 kW/m², roughly 5–11 % of the boiling flux), the sensible cost of warming inflow to 100 °C before it boils (~10–13 % per unit mass, and internal to the evaporation pipeline rather than a true loss), and spray and superheated vapor that recondense locally (a few percent). These sum to roughly a fifth to a third of the delivered energy, leaving a latent fraction of approximately 0.75 (range 0.70–0.82), with the flash-dominated charging phase toward the high end and the broader-surface discharge phase slightly lower. This fraction is bounded by the Clausius-Clapeyron boiling cap, not assumed.

The throughput. Converting the boiling-phase energy at this latent fraction (water mass = f_lat · E / L_v, L_v = 2.257 × 10⁶ J/kg) gives the cumulative evaporative throughput over the active phase:

Across both flux cases and the latent-fraction range, the active phase cycles ~2.8–3.9 ocean volumes of water. This is gross water cycled — water lifted and returned many times over the active centuries, not water removed from the ocean. The overwhelming majority of it rains back to the sea within days and is evaporated again. Only the small fraction that falls where it cannot melt is a net withdrawal.

The requirement. On the pre-event surface there was no continental ice; the high-latitude baseline was temperate, not frozen. The mechanism must therefore account for all present ice, not merely the ice that later melted back at the close of the glacial. The target is the present permanent sheets (~30 million km³ water-equivalent, dominated by Antarctica) plus the water held at the glacial maximum (the 120–134 m lowstand, ~43–48 million km³): a total of approximately 73–78 million km³ of water-equivalent ice at peak accumulation.

The result — required snowfall fraction. Dividing the requirement by the throughput gives the fraction of cycling water that must fall and persist as high-latitude snow to build the entire inventory:

~1.4–2.1 % of throughput, central ~1.7 %.

That is the whole demand on the climate. Of every hundred units of water the boiling basins cycle through the atmosphere, fewer than two need to end up as persistent land ice to produce every ice sheet on Earth, present and glacial-maximum, from an ice-free start.

What this does and does not establish. It establishes that supply is not the constraint. A water budget of several ocean volumes against a requirement of under two percent retention means the mechanism is not straining to find enough water — the moisture is abundant by a wide margin, and the binding question lies entirely on the retention side. What it does not establish is that the retention happens. Whether ~1.7 % of the cycling water actually falls and persists as snow depends on the temperature at the deposition surface, and that is unresolved here. The post-event gradient is steep — a scorching equator against far cooler poles — but the poles are not established as colder than today in absolute terms; the whole system runs warm, and a temperate pole makes persistent accumulation a real question rather than an automatic one. Net accumulation requires the deposition surface to stay below freezing across the season often enough that summer melt does not erase the winter's snow, and resolving that requires the spatial climate-and-hydrology model the main text identifies as beyond present tools. The retention fraction — not the water supply — is the quantity that model must determine, and ~1.7 % is the value it has to land near.

The age of the present Antarctic sheet, which this calculation treats as post-event ice built during the boiling phase and never melted, and its reconciliation with ice-core dating methods, are addressed in the Dating Capstone.

Energy values and phase boundaries are taken from "What Broke the Foundations?" Appendix F (bounding cases computed independently by Claude (Anthropic) and Grok (xAI)). The supply calculation and latent-fraction accounting were developed by D. L. White with Claude; the figures were independently checked against the heat-budget tables.

Related in the Diaspora Series:

• Part One: Where Did the Dove Find Peace?
• Part Two (main paper): When Did the Waters Part?

Next in the Diaspora Series → Where Did the Kinds Walk?

© 2026 D. L. White. Licensed under CC BY-ND 4.0. https://creativecommons.org/licenses/by-nd/4.0/

This paper was developed collaboratively using Claude (Anthropic) for technical modeling, calculations, and co-development of the reasoning chain. Earlier qualitative climate profiles were independently derived by Grok (xAI). The energy balance model was implemented in climlab (Rose, 2018), calibrated to modern global mean temperature (A=193, D=0.7, B=2.0), and driven with volcanic aerosol forcing and an estimated cloud albedo forcing tied to the master clock. Neither AI system endorses all conclusions as settled.