Sea Level Rise
Oceans are about 7-8 inches higher than they were in 1900 (3 inches were added since 1993). The rate of rise this past century was greater than any other century in the past 2,000 years. According to Climate Central, NOAA, FEMA, and USGS, by 2030, storm-driven floods reaching 4 feet above the high-tide line will occur twice as often as today.
In the U.S., of the 25 most densely populated and rapidly growing counties, 23 are along a coast facing exposed infrastructure networks, saltwater contamination, immobilization of transportation, and grid failures, resulting in the potential for prolonged disruption of normalcy.
What is Sea Level Rise?
Sea Level is the average base level for coastal areas to measure elevation against the shoreline. Sea level is measured both by tidal gauges and satellites and can be reported as a global average or as local rates. Changes in mean global sea level, resulting from the transfer of fresh water from land to oceans (from land-based ice sheets and mountain glaciers) and from the thermal expansion of ocean water due to higher global temperatures, contribute to sea level rise.
NASA predicts that the next moon wobble will directly impact American coastlines in the mid-2030s. The higher seas, amplified by the lunar cycle, will cause a leap in flood numbers on almost all U.S. mainland coastlines, Hawaii, and Guam. Only far northern coastlines, including Alaska’s, will be spared for another decade or longer because these land areas are rising due to glacier melt reducing the pressing weight across the surface area.
A Sea Level Rise Study indicated a 100-year storm surge, which is expected to begin occurring every 3–20 years, could cost billions of dollars in direct damages from 1 foot of sea-level rise. As more water enters the ocean through melting glacier runoff and thawing permafrost as well as thermal expansion of water under direct heating, the sea level rises to threaten coastal infrastructure and populations.
Impacts to Critical Infrastructure from Sea Level Rise
Impacts to infrastructure from sea level rise can include flooding, erosion of supporting soils, collapse of buildings, surges of saltwater into waterways, and transportation delays for aviation, ports, roadways, and railways near the coasts. A third of 55 coastal sites in the US will see 100-year storm surges become 10-year or more frequent events by 2050 (NOAA).
Increases in relative sea levels threaten coastal infrastructure, through direct inundation and in combination with storm surge and king tides. Major energy, communication, and transportation centers are located on coastlines, putting their operations and physical safety at risk as sea levels rise.
- Many of the approximately 104 nuclear power plants in the U.S. are situated along the coast due to nuclear plants requiring water for cooling purposes. These facilities and their supporting infrastructure are at risk of damage with rising sea levels.
- In the US, 300 energy facilities are on land at or below 4 feet, including natural gas infrastructure, electric power plants, and oil and gas refineries.
- Ports, docks, bridges, airports, underpasses, dams, roadways, pipelines, and railways all have sea level rise risk from increased floodwater exposure, erosion, and heightened storm surges.
- Flooding in or near production facilities can cause damage to materials, products, and machinery and could cause delivery delays and disrupted supplies.
- Datacenters in Miami, Ashburn, Philadelphia, Boston, and New York City on the east coast and Los Angeles, San Francisco, Santa Clara, and Seattle on the west coast are some of the largest in the US and are within 80 miles of coastlines at risk of flooding.
- Residential homes and community infrastructure have reportedly fallen into oceans on all US Coastlines over the past five years.
Beyond the facilities, rising sea levels threaten critical infrastructure operations.
- Fiber lit buildings which provide bandwidth capacity (traffic) for end-users and data centers and can be damaged in large flood events.
- Undersea cable landing stations connect submarine cables to land-based power and networking infrastructure located along coasts.
- As seas rise, saltwater is contaminating freshwater aquifers and entering river systems which threatens local water supplies due to salinity surges.
Read more about sea level rise
These resources offer more information on rising sea levels and its impact on critical infrastructure systems.
This map displays rising sea level trends using local relative sea levels (RSLs) versus global sea level trends. NOAA provides insight on how sea level data is collected and analyzed to determine global sea levels.
This interactive map allows you to view sea level rise and potential coastal flooding impact areas and relative depth.
NASA provides insight on sea levels using satellite imagery and offers a set of climate and data analysis tools that help you to visualize and access sea level information.
This page provides the EPA's answers to questions about how much the sea has risen, how much it might rise, and what the impacts might be.
This assessment summarizes how sea levels are changing, why they are changing, and what is projected for the future.
This report is intended to inform park planning and adaptation strategies for resources managed by the National Park Service. Understanding projections for continued change can better guide protection of such resources for visitor safety and fun.