Earth’s hypsometry and what it tells us about global sea level
Bibliographic record
Abstract
Over geological time scales, the combination of solid-Earth deformation and climate-dependent surface processes have resulted in a distinct hypsometry (distribution of surface area with elevation), with the highest concentration of surface area focused near the present-day sea surface. However, this distinctive signature of Earth’s hypsometry does not constitute a single well-defined maximum at the present-day sea surface (0 m). Earth’s hypsometry also shows a prominent maximum ~5 m above the present-day sea surface. Here we explore the nature of this 5-m maximum and examine how it evolved over the last glacial cycle and may evolve moving towards a near-ice-free future. We find that the current elevation of this 5-m hypsometric maximum cannot be explained by ongoing sea-level adjustments following the last glacial cycle. Instead, we suggest that global sea level must have been higher for a significant portion of Earth’s recent multi-million-year history. Indeed, global sea level must have been higher by as much as ~9.5 m to bring this hypsometric maximum in accordance with the sea surface, to account for glacial isostatic adjustments such as ocean syphoning. This signifies that our current polar ice-sheet and sea-level state (and our global reference level) should be considered an anomaly in a geological perspective.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.008 | 0.002 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".