California Faces WHEN RISING SEAS HIT HOME

The Union of Concerned Scientists (UCS) identifies several California communities, including Alameda and San Mateo, that face 'chronic inundation'—defined as high tide flooding 10% or more of usable land at least 26 times per year—by 2100 under intermediate sea level rise scenarios. In a high-rise scenario, this timeline accelerates to 2080. The report highlights specific risks to military installations in San Diego and developing neighborhoods in San Francisco. However, the document notes that limiting warming to approximately 1.8°C (the 'low' scenario) could prevent any California community from reaching the 10% chronic inundation threshold by the end of the century. To address these risks, the UCS advocates for halting risky coastal development, enhancing disaster response funding, and creating new policies for managed retreat and relocation.

• Under the intermediate sea level rise scenario, three California communities—Alameda, San Mateo, and the North Coast (including Huntington Beach)—will face chronic inundation by 2100. If the high scenario occurs, this timeline moves up to 2080. By 2100, the number of affected communities in California increases to seven.
• Certain areas will experience severe flooding even if they do not meet the 10% total land area threshold for chronic inundation. By 2100 in the intermediate scenario, Balboa Island in Newport Beach and Naples Island in Long Beach would flood on average every other week. In San Francisco, disruptive flooding would reach the Hunters Point and Mission Bay neighborhoods by 2100.
• Military infrastructure in San Diego is highly vulnerable to sea level rise. In the high scenario, the piers at Naval Station San Diego would face frequent flooding by 2060. By 2100, more than one-third of both the Marine Corps Recruit Depot San Diego and Naval Station San Diego would flood regularly, as well as the majority of Naval Amphibious Base Coronado.
• Limiting global warming to approximately 1.8°C (represented by the 'low' scenario) would ensure that no California community experiences chronic inundation of 10% of its land area before the end of the century.

APA

Union of Concerned Scientists (2017). California Faces WHEN RISING SEAS HIT HOME. https://www.ucs.org/sites/default/files/attach/2017/07/when-rising-seas-hit-home-california-fact-sheet.pdf

Chicago

Union of Concerned Scientists. California Faces WHEN RISING SEAS HIT HOME. 2017. https://www.ucs.org/sites/default/files/attach/2017/07/when-rising-seas-hit-home-california-fact-sheet.pdf.

Wikipedia

{{cite report |author=Union of Concerned Scientists |title=California Faces WHEN RISING SEAS HIT HOME |date=July 2017 |url=https://www.ucs.org/sites/default/files/attach/2017/07/when-rising-seas-hit-home-california-fact-sheet.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{unionofconcernedscientists2017california, author = {{Union of Concerned Scientists}}, title = {{California Faces WHEN RISING SEAS HIT HOME}}, institution = {Union of Concerned Scientists}, year = {2017}, month = jul, url = {https://www.ucs.org/sites/default/files/attach/2017/07/when-rising-seas-hit-home-california-fact-sheet.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }