Caltrans released its first Climate Change Vulnerability Assessment in compliance with Governor Jerry Brown’s Executive Order B-30-15, to “integrate climate change into transportation investment decisions,” which was issued two years ago.

Caltrans Director Malcolm Dougherty explained Caltrans position on climate change in the statement that accompanied the release of the study in late December:

“Climate change poses an immediate and growing threat to California, and Caltrans is being proactive in determining what this means for the state’s transportation system. This study and those that will follow intend to provide data to support the discussion about how climate change impacts the way we plan, design, build, operate and maintain the state highway system.”

This first report, which covers San Francisco Bay Area region’s (Caltrans District 4) infrastructure, will be the template that the 11 other districts use to address “the impact of climate change” on their plans.

It is presumed that the districts away from the coast won’t use the bits about sea level rise and confine themselves to “more frequent wildfires, changing precipitation patterns and increasing temperatures associated with climate change.”

Where’s the Action

Caltrans’ District 4 Climate Change Vulnerability Assessment identifies specific locations along the State Highway System in the Bay Area that may be impacted by rising sea levels and larger storm surge, according to the report. It is split into two sections—the more or less English version with photos and a more technical document where the details backing up the policy reside.

This table is from page 24 of the technical report in this study and reports the miles of road that will be affected by climate change sea level rise caused by county in District 4:

Caltrans Releases_table1

The estimated sea-level rise numbers come from the 2018 update of California’s Sea Level Rise Guidance: 2018 Update (Draft), released in November, 2017 by the Ocean Protection Council (OPC) and California Natural Resources Agency.

The sea level rise estimates in Caltrans report are at odds with the official sea level rise report from the National Oceanic and Atmospheric Administration, (NOAA) which provided the chart below with the explanation:

“The mean sea level trend is 2.15 millimeters/year with a 95% confidence interval of +/- 0.19 mm/yr based on monthly mean sea level data from 1906 to 2016 which is equivalent to a change of 0.70 feet in 100 years.”

Caltrans Releases_table2

As you can see the actual real world measurements (not algorithmic models) of sea level is California, none of the coastal areas will see anything like the 1.64-5.74 foot rise projected by the state, but, instead, may rise by seven tenths of a foot (roughly 8 1/2 inches) in 100 years.

If you want to read the two reports, Caltrans’ current policy and guidance documents can be found at //www.dot.ca.gov/transplanning/ocp/cc-policyguidance.html