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Interactive Tool for Assessing Climate-Change Impacts Along the North-Central California Coast Supported by USGS Modeling System

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Photo of unusually high tides, called 'king tides'

Above: Unusually high tides, sometimes called "king tides," offer a preview of coastal flooding likely to result from rising sea level. In this photograph, taken during a king tide on February 17, 2011, waves overtop Pier 14 in San Francisco, California. (Towers in background are supports of the San Francisco-Oakland Bay Bridge.) Photograph by Mike Schweizer. [larger version]

Screenshot of interactive map  from Our Coast Our Future

Above: Screenshot of interactive map (with added place names) from Our Coast Our Future (OCOF) Web site. Map shows most of the shoreline currently covered by the Climate Impacts Tool for assessing climate-change impacts along the north-central California coast, from Half Moon Bay to Bodega Bay, California (Bodega Bay is just beyond top of map). White arrow points to location of Muir Beach images, below. [larger version]

U.S. Geological Survey (USGS) scientists, in collaboration with the National Oceanic and Atmospheric Administration (NOAA) and PRBO Conservation Science (formerly Point Reyes Bird Observatory), recently released the beta version of an interactive tool for assessing climate-change impacts along the north-central California coast. The new Climate Impacts Tool, which currently covers the California coastline from Half Moon Bay to Bodega Bay (see map), was posted on February 20, 2013, at http://data.prbo.org/apps/ocof/. The new tool is part of Our Coast Our Future (OCOF), a project that seeks to provide science-based decision-support tools to natural-resource managers, local governments, and others in the San Francisco Bay region to help them understand, visualize, and anticipate local coastal climate-change impacts within the bay and along the outer coast.

The technical underpinning of the new Climate Impacts Tool is the Coastal Storm Modeling System (CoSMoS), a numerical modeling system developed by the USGS and Netherlands-based research institute Deltares to predict coastal flooding caused by both sea-level rise and storms driven by climate change.

Sea level along the California coast is expected to rise by as much as 1.7 meters (approximately 6 feet) by 2100 (National Research Council, 2012, http://www.nap.edu/catalog.php?record_id=13389). Winter storms can elevate coastal water levels by an additional 5 meters (approximately 16 feet) or more, primarily because of large waves and storm surge (rise in water level caused by low atmospheric pressure and wind). The additional water-level rise caused by severe storms is addressed in the CoSMoS modeling system, enabling its users to more accurately assess the future vulnerability of coastlines to flooding caused by climate change.

CoSMoS modeling begins with feeding the results of the latest global climate models (from an international clearing house at http://cmip-pcmdi.llnl.gov/cmip5) into a global wave model to predict wave conditions for the U.S. west coast through 2100. These offshore wave conditions, combined with predicted tides and storm surge, are scaled down to the local level with state-of-the-art numerical modeling tools to predict coastal water levels. The water levels are then projected onto a digital elevation model (DEM) with a 2-meter grid (a grid consisting of squares 2 meters on a side, with each square assigned an elevation value). DEMs, like the more familiar topographic maps, show the shape and elevation of the ocean floor and land surface; projecting predicted water levels onto coastal DEMs can be used to estimate the likely extent of flooding. For the north-central California coast, CoSMoS has performed this exercise across the full plausible range of anticipated sea-level rise and storm conditions predicted by the global climate models.

The USGS CoSMoS team includes project manager Patrick Barnard (who is also co-principal investigator, along with Grant Ballard of PRBO Conservation Science, on the Our Coast Our Future project), lead modeler/coastal engineer Li Erikson, geologist Amy Foxgrover, and oceanographer Andy O'Neill. Deltares collaborators include Maarten van Ormondt and Edwin Elias.

The CoSMoS team is currently expanding the modeling system to support coastal-management decisions along shorelines in San Francisco Bay and southern California. CoSMoS not only can serve as a long-term planning tool, but—when extreme storms are approaching—is capable of serving as a real-time warning system for emergency managers, lifeline operators, and resource managers.

Screenshot of OCOF interactive map shows present coastline during non-storm conditions Screenshot of same area, showing extent of flooding predicted if the area is subjected to a sea-level rise of 75 centimeters
Above Left: Screenshot of Our Coast Our Future interactive map view of Muir Beach, California, showing present coastline during non-storm conditions. [larger version]

Above Right: Screenshot of same area, showing extent of flooding predicted by the recently released Climate Impacts Tool if the area is subjected to a sea-level rise of 75 centimeters (about 30 inches) and elevated water levels caused by a 20-year-recurrence-interval coastal storm with an offshore wave height of 9.1 meters (approximately 30 feet). [larger version]

Learn more about CoSMoS in The Framework of a Coastal Hazards Model—A Tool for Predicting the Future Impact of Severe Storms (USGS Open-File Report 2009–1073) at http://pubs.usgs.gov/of/2009/1073/ or contact Patrick Barnard, pbarnard@usgs.gov. Learn more about Our Coast Our Future at http://data.prbo.org/apps/ocof/. For an explanation of climate modeling, see http://www.wmo.int/pages/themes/climate/climate_models.php.

Related Sound Waves Stories
Meeting of Experts on Key Drivers of Central California Coastal Change and Inundation Due to Climate Change
July / August 2012

Related Websites
The Framework of a Coastal Hazards Model—A Tool for Predicting the Impact of Severe Storms
Our Coast Our Future
Climate Models
World Meteorological Organization

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Juvenile Surf Smelt and Sand Lance in Central Puget Sound, Washington

Groundbreaking Gas Hydrate Research

Interactive Tool for Assessing Climate-Change Impacts

Sooty Shearwater Migration on Display

Future of Pacific Northwest Seagrasses in a Changing Climate

Staff USGS Postdoctoral Researcher Studying Effects of Dam Removal


Mar. / Apr. 2013 Publications

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