Surging Seas Sea level rise analysis by Climate Central

About Surging Seas Map

How to Use the Map | What the Map Shows | Where the Map Comes From | Map Accuracy

How to Use the Map

Type place names in the search box, or click on map labels, to zoom to towns, cities, counties, states or zip codes, and see associated statistics.  Click on decade balloons (visible only in some locations) to go to flood study station pages.

Use the slider in the left sidebar to select different water levels from 1-10 feet above local high tide.  This action will update the map to show what land is below water level, and associated statistics.

Share the exact map view you see by clicking on the twitter or facebook icons at the top of the sidebar.

Click on list cities or counties to display city or county labels on the map, and ranked lists in the sidebar (taken from the map extent).  Use the dropdown menu at the top of the list to choose what to rank the list by.

Navigate by zooming and panning like a regular web map.  Click on the Lower 48 icon to go to a national view.

If the display seems to freeze or get buggy, try refreshing your browser while holding down the shift key.  If you find a true bug, please contact us by clicking on “Report bug” on the sidebar footer.

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What the Map Shows

Map areas below the selected water level are shown as satellite imagery with blue margins.  Within the areas below water level, street labels have blue backgrounds (visible at near zooms).

Map areas above the selected water level are shown in map style using white and pale grays.

Ocean area close to shore is visible as part of the satellite imagery.  Ocean area farther from shore is depicted with a symbolic blue wave pattern.

Decade balloons pinpoint 55 locations where local sea level rise projections were combined with storm surge and tidal statistics to estimate the decade by when there is an at least 1 in 6 chance of different water levels occurring, at least once.

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Where the Map Comes From

All map elements and statistics pertaining to the area under different water levels are based on methods published in this peer-reviewed scientific paper, and also explained on this page.  Estimated decades and odds of flooding are based on methods published in this paper, with some extensions also described here.

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Map Accuracy

The map shows best estimates of land under different water levels, based upon the National Elevation Dataset from the US Geological Survey — the best publicly available elevation data covering the entire US coast. Errors within this massive dataset mean that many points are actually higher or lower than depicted, and thus may be misclassified relative to some of the water levels shown. Caution is therefore advised in drawing any conclusions about individual points or addresses on the Surging Seas map. However, errors should mostly cancel out when averaged across larger areas, so greatly more confidence can be placed in the statistics presented for cities, counties and states. This is analogous to how a baseball player’s career batting average characterizes his skill much better than his performance in just one game (which is like dataset performance at just one address).

Individuals or organizations seeking address-level information should seek laser-based “lidar” elevation data, available for some areas, or make their own elevation measurements using high-accuracy instruments such as differential GPS — making sure in either case to reference their findings to the elevation of local high tide.

For more discussion of elevation error and tidal references, see this scientific paper.

Additionally note that land under a given water level will not necessarily flood if the ocean nearby reaches the same level. Some areas may be protected by topography, levees, seawalls or other structures, and this analysis does not account for such protections. The analysis simply indicates features below different elevations. On the other hand, some low areas which appear isolated or protected may in fact be connected to potential flood zones by ditches, waterways, or sewage lines too fine to detect or include in the elevation dataset used.

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