West Coast Sea Level Projections

As a water resources professional who regularly handles issues related to climate change and water planning, I have noted in past that one of the key missing data points in scientific studies related to climate change is a reliable projection of sea levels. This is important because sea level is a key input for determining the potential impact of climate change on coastal groundwater basins. Such basins frequently have both on-shore and off-shore areas, and intrusion of seawater into the on-shore portion is affected by the relative head of groundwater in the two areas. The head of groundwater in the off-shore portion is directly related to sea level, such that a rising sea level would increase the head in off-shore basins and tend to push seawater toward or into the on-shore portion.  Seawater intrusion can be a significant problem for management of coastal basins and the water utilities, industries and individuals that rely on those basins for water supply.

State agencies from California, Oregon and Washington, along with the National Oceanic and Atmospheric Administration (NOAA), US Army Corps of Engineers (USACE) and US Geological Survey (USGS) have commissioned a study by the National Research Council (NRC) on projected sea levels for the West Coast for 2030, 2050 and 2100. The study is supposed to: evaluate the major contributions to sea level; project sea levels for 2030, 2050 and 2100 on global, regional and local bases; and evaluate remaining uncertainties in those projections.

The California agencies are holding public meetings on June 8, 16 and 17, 2010 to solicit reference information and data that might be useful to the NRC study (see Sea Level Study Notice of Public Meetings). It is expected that the first science review committee meetings will be held in the fall of 2010, with the results of the study finished in late 2011 or early 2012. Hopefully, the process will not be co-opted along the way by special interest groups, and the report will provide useful, science-based information to water managers along the West Coast.

2 Comments on “West Coast Sea Level Projections

  1. Enjoy reading your blog, Wes. Indeed, the NRC report, if done well, will be a welcome addition to the literature for lots of resource managers.

    As to the usefulness of current sea level rise estimates, there aren’t really reliable estimates of anything related to climate change, are there? There are plenty of scenarios out there, the most well-known being the IPCC’s SRES, or Special Report on Emissions Scenarios. T But no one wants to assign a likelihood to any of them, as it would require predicting the behavior of human societies and governments.

    We can say with certainty how much seas have risen in various places in the past, thanks to our long-running tide gages. Take a look at NOAA’s Sea Level Trends Online:


    Lastly, while saltwater intrusion is a pressing issue, I would argue that, at present, overdraft and mismanagement are putting about 1,000 times more stress on our aquifers than sea level rise.

  2. Matthew,

    Thanks for the link to NOAA sea level trends. You are right that there are no current reliable projections on sea level rise, so this new effort will be interesting to see if they can generate something useful. I don’t pretend to be a scientist, so there may be data or studies I don’t know about.

    Seawater intrusion is a major problem in some coastal aquifers in California, although it was a larger problem a couple decades ago and is now managed fairly well most places. If there were a significant sea level rise, though, those efforts would have to be upgraded no doubt.


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