Sea Level Map

Data

Here, we present high-quality data sources and models that provide invaluable insights into the intricate dynamics of sea level and ice sheet interaction. Our data page has been organized into relevant categories for easy navigation:

We strive to maintain transparency and proper attribution; therefore, all our listed data sources include necessary citations, contributing to the integrity and reproducibility of scientific research.

Global relief map showing land and seafloor as they stood during the last ice age

Data in the Map

What the map draws, and where each layer comes from:

  • Sea level and coastlines - Relative sea level computed by Dr. Jacky Austermann with a glacial isostatic adjustment model, from the ICE-6G_C ice history, and shared for this project. Applied to today's bedrock, it shows the land pressed down under the ice sheets and lifted around them, not a single global sea level. Attribution: J. Austermann (personal communication); Peltier, W.R., Argus, D.F., Drummond, R., 2015.
  • Sea level and coastlines, 50,000 to 80,000 years ago - Relative sea level from the glacial isostatic adjustment model (SELEN) run on the ICESHEET 2.0 ice, published with it as PaleoMIST 1.0 under CC BY 4.0. Used for these steps because it fits the dated sea level evidence (GAPSLIP) better there than the model above and matches the ice the map draws. It puts sea level about 50,000 years ago higher than the global curve in the sidebar does. Attribution: Gowan, E.J., Zhang, X., Khosravi, S., et al., 2021.
  • Sea level figures and graphs in the sidebar - Global mean sea level and its 95% uncertainty range, from a stack of seven sea level reconstructions based on marine sediment cores. It is a global average, so it differs from the local sea level the map's coastlines show, most of all near the former ice sheets. Attribution: Spratt, R.M., Lisiecki, L.E., 2016.
  • Bedrock and seafloor - GEBCO global grid with sub-ice topography, also drawn as the map's shaded relief and raised by the 3D button. Attribution: GEBCO Compilation Group.
  • Ice sheets to 80,000 years ago - ICESHEET 2.0, published as PaleoMIST 1.0 under CC BY 4.0. Attribution: Gowan, E.J., Zhang, X., Khosravi, S., et al., 2021.
  • Ice sheets beyond 80,000 years - The ICE-6G_C ice history that the sea level model was run with, extended through earlier glacial cycles. It repeats ICE-6G's ice shapes from one cycle to the next, so the map treats it as schematic. Its thickness also shades the ice at every step, trimmed to ICESHEET's outlines up to 80,000 years ago. Attribution: J. Austermann (personal communication); Peltier, W.R., Argus, D.F., Drummond, R., 2015.
  • Mountain glaciers at the Last Glacial Maximum - The glaciers of the world's mountain ranges, from the Andes, the Alps and the Himalaya and Tibet to New Zealand, shown at the 24,000 and 20,000-year steps. Each range reached its greatest extent at its own time, between about 57,000 and 14,000 years ago, so they show the glaciers' greatest extent around the Last Glacial Maximum rather than at one moment; glaciers smaller than 25 km² are left out. They come from the authors' filtered layer of GLACIMONTIS, a compilation of 15,014 glacier reconstructions from 209 studies of 271 mountain ranges. Attribution: Lima, A.C., Dulfer, H.E., Hughes, A.L.C., Margold, M., Barr, I., Laabs, B.J.C., Flantua, S.G.A., 2025, GLACIMONTIS (version 1), and the original studies it compiles, listed in the GLACIMONTIS worksheet; described in Mountain glacier extents at the Last Glacial Maximum, Scientific Data (2026). Licensed under CC BY 4.0.
  • Greatest ice extent in earlier glaciations - The dashed red line on the steps beyond 80,000 years, shown with the Evidence button: the greatest extent the Northern Hemisphere ice sheets reached during MIS 5b, MIS 6, MIS 8 and MIS 10 (and during the warmest part of MIS 5c), compiled from the geological evidence. Each line is the ice's limit at any time within that stage, not the ice at one moment; ice masses and ice-free areas smaller than 20,000 km² are left out. The evidence for MIS 8 and 10 is thin and debated. Attribution: Batchelor, C.L., Margold, M., Krapp, M., et al., 2019, The configuration of Northern Hemisphere ice sheets through the Quaternary, Nature Communications 10, 3713; best-estimate reconstructions from the authors' repository, shown with Dr. Batchelor's permission.
  • Proglacial lakes in North America - The meltwater lakes along the retreating ice, at seven steps from 20,000 to 5,000 years ago, matched to the ice shown and converted from radiocarbon to calendar years with IntCal20. Attribution: Dyke, A.S., Moore, A.J., Robertson, L., 2003, Deglaciation of North America, Geological Survey of Canada Open File 1574, Natural Resources Canada, as reprojected by A. Wickert; not endorsed by Natural Resources Canada.
  • Proglacial lakes before 20,000 years - Modelled, not mapped: where meltwater pooled against the ice sheets on land pressed down by them, through the last glacial cycle, from the paper's default run. Shown at six steps from 100,000 to 24,000 years ago, keeping only lakes of 500 km² or more beside the ice drawn on the map, as the model's own ice differs. Attribution: Austermann, J., Wickert, A.D., Pico, T., Kingslake, J., Callaghan, K., Creel, R.C., 2022, Glacial isostatic adjustment shapes proglacial lakes over glacial cycles, Geophysical Research Letters; data, CC BY 4.0.
  • Sea level evidence - Dated sea level indicators (shells, peat, corals, raised beaches and other samples) from the Global Archive of Paleo Sea Level Indicators and Proxies (GAPSLIP), version 2.1, shown with the Evidence button. Each record is placed on the time step nearest its age, within 500 years for recent steps and up to 3,000 years for older ones, and shows whether sea level stood at that height, above it or below it. Around the Baltic from about 16,900 to 9,500 years ago the records give the level of the Baltic basin, which was a lake for much of that time. Most records are from the last 15,000 years. Attribution: GAPSLIP, compiled by E.J. Gowan from the work of the PALSEA and HOLSEA communities; Gowan, E.J., 2023, GEUS Bulletin 53; Gowan, E.J., et al., 2021, Nature Communications 12, 1199. Licensed under CC BY-SA 4.0, so the map's evidence file, built from it, is shared under the same licence.
  • The slider beyond 400,000 years - No data of its own: each step from 414,000 to 500,000 years ago borrows the coastlines and ICE-6G ice (both above) of a time in the sea level model's record when global sea level was about the same, in the same phase of the ice age cycle, matched to the global sea level curve (Spratt & Lisiecki 2016). The sidebar names the time each step borrows. Schematic.
  • Basemap - Natural Earth, public domain.

Ice Age Cycles over 2.6 Million Years

The map covers the last five ice age cycles, but the cycles go back much further. For most of the Pleistocene the ice sheets grew and melted about every 41,000 years, in step with slow changes in the tilt of Earth's axis, and sea level rose and fell by about 25 to 50 meters. Between about 1.2 million and 700,000 years ago, in the Mid-Pleistocene Transition, the rhythm changed: the ice sheets grew larger and lasted longer, and the cycles stretched to about 100,000 years, with sea level falling by 70 to 120 meters or more.

0 m −50 m −100 m Today's sea level 2.5 million 2 million 1.5 million 1 million 500,000 Today years ago Cycles of about 41,000 years Mid-Pleistocene Transition About 100,000 years The map Berends et al. 2021, modeled, with its range The map's curve, Spratt and Lisiecki 2016
Global mean sea level since the start of the Pleistocene, relative to today. Blue: modeled by Berends et al. (2021), with its range. Orange: the curve under the map's slider (Spratt and Lisiecki 2016) over the 800,000 years it covers. The model's glacial lows are shallower than this and most other estimates. Shaded on the left: the span the map covers.

Why the cycles lengthened, when the changes in Earth's orbit that pace them did not, is still debated. So is why they settled near 100,000 years, the period of changes in the shape of Earth's orbit, which on their own alter the sunlight Earth receives only slightly. Together these questions are known as the 100,000-year problem. Each recent cycle builds its ice slowly, over tens of thousands of years, then loses most of it in about ten thousand: after the Last Glacial Maximum, around 20,000 years ago, sea level rose by about 120 meters, reaching close to today's level by about 7,000 years ago. The curve under the map's slider is drawn to scale in time, so that rise shows there as a near-vertical wall at its left end.

  • Sea level over 2.6 million years - Modeled global mean sea level and its range, from an ice sheet and climate model driven by the LR04 stack of deep-sea oxygen isotope records. Attribution: Berends, C.J., de Boer, B., van de Wal, R.S.W., 2021, Reconstructing the evolution of ice sheets, sea level, and atmospheric CO2 during the past 3.6 million years, Climate of the Past 17, 361-377; data, CC BY 4.0. The map's curve: Spratt, R.M., Lisiecki, L.E., 2016.

Bathymetry Data & Maps

  • GEBCO Gridded Bathymetry Data - Provides gridded bathymetry data compiled by The General Bathymetric Chart of the Oceans (GEBCO). Attribution: GEBCO.
  • NOAA Seafloor Mapping - An array of data and maps by the National Oceanic and Atmospheric Administration (NOAA) related to the mapping of the seafloor. Attribution: NOAA's National Centers for Environmental Information (NCEI).
  • NOAA ETOPO Global Relief Model - ETOPO1 Global Relief Model offering topographic and bathymetric data. Attribution: NOAA's NCEI.
  • NOAA Coastal Elevation Models - Elevation models for the coastal region from NOAA. Attribution: NOAA's NCEI.
  • NOAA Bathymetry - Hydrographic Survey Data - Hydrographic data for studying bathymetry. Attribution: NOAA's National Geophysical Data Center.
  • Arctic Bathymetry Data - Bathymetry data specific to the Arctic region. Attribution: NOAA's National Geophysical Data Center.
  • Data from a Sea-Level Compilation - Raw data of sea-level compiled in the PANGAEA Data Publisher for Earth & Environmental Science. Attribution: PANGAEA.

Ice Sheet Reconstruction Data & Maps

Climate Cycle - Glacial - Interglacial

Paleoclimatology & Paleoceanography

  • NOAA Paleoclimatology Program - Provides access to a comprehensive array of climate proxy data, paleoclimate reconstructions, and climate modeling data. Attribution: NOAA.
  • A Late Pleistocene sea level stack - Global mean sea level over the past 798,000 years, averaged from seven sea level reconstructions based on marine sediment cores, with its 95% uncertainty range. The sea level figures and graphs in the map's sidebar come from it (data). Attribution: Spratt and Lisiecki, 2016.
  • Past Global Changes (PAGES) - Provides access to various databases and working groups dealing with different aspects of paleoclimatology. Data attribution: Past Global Changes (PAGES), an international project funded by IGBP.

The sea level stack combines seven records:

With Thanks

While building this map we corresponded with sixteen scientists whose research it draws on. They shared data and model results, answered questions and pointed us to sources. We thank them here for that generosity; they did not review or endorse the map, and any errors in it are ours.

We encourage you to explore these resources and utilize the data and models to deepen your understanding of sea levels and their impact on our planet. As scientific knowledge evolves, so will our database, ensuring that you always have access to the latest and most accurate information on sea levels.

Contact us with questions or if you would like to contribute to this project.