Sea Level Rise

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I researched and wrote this because powerful companies want to develop North Sunnyvale.  This will be a nightmare to undo as will be seen in just 10 or 20 years when the flooding goes from yearly to monthly to permanent.  By publicizing this as much as possible, I hope to avert the disastrous development of housing there.

I hope Sunnyvale residents and city staff spend the time to go through the many documents I have selected from the multitude I read.  If they do, I am sure they will decide against any residential development in that area.

The extent of Sea Level Rise based on the scientific consensus has been published by California state agencies so that cities and counties can make plans on development near coastal areas.  Below are many references to government documents & scientific papers with real numbers for guidance and planning.

Sunnyvale: 2050 Sea Level Rise

Sunnyvale: 1 foot Sea Level Rise (SLR)

Sunnyvale: 1 ft SLR + 3 ft Flood = 4 ft

The 1 foot of sea level rise shown here is given a 66% chance of happening by 2050 by scientists and state agencies.  The numbers actually provide a range of 1.1 ft to 1.9 ft. so 1 foot by 2050 is conservative.  There is no housing in the 1-ft. SLR area at present, although several companies want to put housing there.

With a storm surge, authorities predict a 4-ft level inundation for a 1-in-10 year flood by 2050 as shown.  That does include some areas currently occupied by mobile homes.  The best thing to do for those areas is to buy them up and convert them into rentals.  The rental income will pay for the purchase before they need to be abandoned.

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Maps from National Oceanographic & Atmospheric Administration (NOAA)

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A dam or levee will not work to keep out water as groundwater levels rise to equalize with the adjacent surface water level. 


Rising groundwater brings to the surface buried toxic wastes which have been deposited over years by military & industrial activity.  Pumps make things worse over the long term as they deplete the aquifers lowering the surface elevation. 


Drawing from:

Rising Groundwater

Sunnyvale: 2100 Sea Level Rise

Sunnyvale: 3 ft SLR + 4 ft Flood = 7 ft

Sunnyvale: Worst Case = 21 Feet

Scientists give the 3 foot sea level rise + 4 ft storm surge shown below a 66% chance of happening by 2100.

The numbers provide a range of 2.4 ft to 6.9 ft. so 3 feet by 2100 is conservative.  Adding in occasional flooding brings it up to the upper end of the range so the map could be 1-in-10 year floods or normal everyday levels depending on how fast the world reduces Greenhouse Gas emissions (GHGe). 


There is a lot of housing in the 7-ft. SLR area.  It will all need to be bought before SLR makes the area uninhabitable.

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Maps shown so far are estimates based on older GHG emissions scenarios.  Higher emissions mean higher sea levels.

In late 2017 a study indicated that Antarctica is losing mass (melting) much faster than had been realized.  Scientists drastically changed estimates.  State documents include this as the "H++" scenario with 21 ft. of SLR by 2150.  "Further study is needed".

Here is what just 16 feet (5 meters) looks like for Sunnyvale.

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Absolute Worst Case


"Rising Seas in California" - This scientific assessment formed the basis for California state recommendations on sea level rise.

"California's Fourth Climate Change Assessment".  Main CA state entry site for climate change.  Contains many reports for all regions and many, many topics.

"What Threat Does Sea-Level Rise Pose to California?".  Very recent  - Aug. 10, 2020.  10 pages.

"Assessing Vulnerability of State Assets to Climate Change"

Contains valuable charts and tables.

"State of California Sea Level Rise Guidance", 2018.  Table 13 on page 57 gives estimated ranges for the SF Bay area.

"Preparing for Rising Seas".  Excellent summary for local governments on what to expect from imminent Sea Level Rise.

"California's Fourth Climate Change Assessment - Coast and Ocean Summary Report".  Page 18 specifies SLR for SF Bay.

Flood Mapping tool.  Key in various parameters to see areas affected:

USGS Coastal Storm Modeling System

Inundation database map

CA state Dept. of Transportation - which roads and bridges will be flooded under different scenarios.

CalTrans Interactive Map - SLR and roads/bridges


LA TImes reporter Rosanna Xia has been recognized by the Pulitzer Committee for her reporting on SLR.  Her most recent article:  It was reprinted by the American Physics Society here:

I cover some of the aspects of Sea Level Rise in blog posts:




The earth's average temperature is currently about 1 deg. C above that of 1890.  That is enough to raise sea levels by several feet.  The earth is very slow to react to changes in temperature.  We won't see the effects of that 1 degree C increase for 50-150 years.

The worst case for SLR ​would be if earth's  temperature rises 2 more degrees (Celsius) to 3 degrees above pre-industrial levels.

At 3 degrees above pre-industrial temperatures, the climate would be like that of the Pliocene period, 3 million years ago.  At that time the seas were higher by between 6 meters and 40 meters (20 ft. to 120 ft.).

This is shown in the image below from the paper


A map of Sunnyvale with 20 meters SLR (worst case mid-point) is shown below.  It would take at least 150 years for this to occur.  Even at those high levels most of Sunnyvale is still above sea level.  There would be plenty of other problems, of course.

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I show this only as the absolute worst case.  I think we can avoid it.

The world is taking action.  Governments and people around the world are rapidly converting to clean energy, clean transport, green buildings.  We can ardently hope to keep temperatures from going above 2 deg. C and avoid this entirely.

Storm Effects

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The US Geological Survey researched the effects of storms on coastal communities.  It estimates that storms can triple the damage and number of people affected.  KQED summary here:


Original report here: