sea level
Let an agent explain sea level and how it is defined and measured, relay tidal, eustatic and past sea level concepts from geodesy, oceanography and geology references, describe sea level rise with findings attributed, and distinguish mean sea level from tide level, geoid and local datums.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
written by Claude from model knowledge without web access - no source was read, every claim is a lead to verify
Researched by: Claude
Purpose and description
Let an agent explain sea level and how it is defined and measured, relay tidal, eustatic and past sea level concepts from geodesy, oceanography and geology references, describe sea level rise with findings attributed, and distinguish mean sea level from tide level, geoid and local datums.
The average level of the ocean surface, used as a vertical datum for measuring elevation and depth, defined locally by tide gauges as mean sea level over a period and globally by satellite altimetry, varying with tides as tide level, with eustatic changes in the volume of the oceans over geological time, and reconstructed as past sea level from geological records; global mean sea level is rising as ice melts and oceans warm.
What it is for: Reference for elevation and monitoring ocean change.
It can be explain definitions; relay measurement; describe sea level change; distinguish related concepts.
Distinguishing features
Vertical datum
Tidal and long-term variation
Global and local
Climate indicator
What it looks like
Not a visible object; the ocean surface as a reference.
Physical character
global mean rise since 1900: about 20 cm
current rate: about 4 mm per year - satellite era
Last Glacial Maximum sea level: about 120-130 m lower note
How it is recognised
Average level of the ocean surface
Mean sea level, tide level, eustatic sea level, past sea level
The geoid is a gravitational surface; local datums differ; tide level varies hourly
Related models
is a kind of - in registry terms
is a kind of - in registry terms
is a kind of - in registry terms
is contrasted with - a gravitational equipotential surface
In practice
Families and kinds
mean sea level at tide gauges
tide level and tidal datums
global mean sea level from altimetry
eustatic sea level
relative sea level including land movement
past sea level from geological records
Standards and regulation
National vertical datum standards
IPCC assessments of sea level change
IHO tidal datum conventions
Failure modes and hazards
Confusing local and global sea level
Ignoring land subsidence in relative sea level
Partisan framing of sea level rise
Also called
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 4 bundles · 8 layers · 8 findings · 16 questions.
Understand What sea level is.
Science.
Definition
Definition.
Definition
Definition.
- What is sea level, and how do mean sea level, tide level, eustatic sea level and the geoid differ? definition
- Is the question about the datum, tides, geology or climate change? boundary
Measurement
Measurement.
Measurement
Measurement.
- How is sea level measured by tide gauges and satellite altimetry? measurement
- Which entry fits tide gauge? action
Change Sea level change.
Science.
Rise
Current rise.
Rise
Rise.
- How fast is global sea level rising, why, and what are projections, as assessments report? provenance
- Which references are standard? provenance
Past
Past sea level.
Past
Past.
- How has sea level changed over geological time, and how is past sea level reconstructed? provenance
- Which sources are cited? provenance
Use Use as a datum.
Practice.
Datums
Datums.
Datums
Datums.
- How do national datums and chart datums relate to mean sea level? provenance
- Which entry fits vertical datum? action
Mapping
Mapping and navigation.
Mapping
Mapping.
- How are elevations and depths referenced to sea level in maps and charts? provenance
- Which entry fits nautical chart? action
Context Impacts and adaptation.
Context.
Impacts
Impacts.
Impacts
Impacts.
- How does sea level rise affect coasts, cities and islands, with findings attributed? provenance
- Is the presentation neutral? boundary
Adaptation
Adaptation.
Adaptation
Adaptation.
- How do communities adapt to rising seas? provenance
- Which entry fits coastal management? action
What the second pass must settle
- Should sea level rise and tidal datum be separate primary entries?
- How should geodesy and climate sources be linked?
- The registry entry has merged aliases naming distinct concepts; should they be split off?