Guest Essay by Kip Hansen
Public Radio is the United States’ sort-of-analog of the United Kingdom’s BBC. While there is a National Public Radio, the various stations in the network are independently owned, usually by public bodies like universities — and subscribe to content from NPR and other content producers such as American Public Media, Public Radio International, Public Radio Exchange and WNYC Studios. Many also produce their own programs locally. Almost all public radio stations in the US have always been far-left of center on political and social issues, they have recently begun to mirror the BBC’s editorial policy of broadcasting any and all alarmist climate change stories without any attempt to verify any information offered as factual, as long as it is in line with the “climate change as catastrophe” meme.
The most recent example came as a real surprise to me last month, when a segment was aired about the threats of sea level rise in the San Francisco Bay area of California. The public radio host was interviewing an advocate/activist from some California-based environmental group about sea level rise in San Francisco Bay.
The punch line of the piece was that “sea level in San Francisco is expected to rise by 7 to 10 feet by 2100” and would thus be a threat even to Silicon Valley.
[ Note: I have spent way too much time attempting to find a trace of the exact content provider that created the story, including emailing NPR’s All Things Considered — to no avail. NPR could not find any such content in programs they produced. I have checked the web sites of APM, PRI and PRX. They don’t list such a program. The segment I refer to was broadcast on WAMC (Northeast Public Radio out of Albany, NY) in early August 2019. My wife and I heard it, and I commented on it at the time… and it could have been produced by any one of the dozens of content providers to public radio stations. ]
7 to 10 feet expected?
This pronouncement was accepted by the program host without the slightest hesitation or question — despite it being almost double the worst-case scenarios from the IPCC.
Let’s look at the real data first, mostly in images, all from the IPCC or NOAA sources:
Past Sea level Rise in San Francisco
The 100-year regional graph for Southern and Central California, which includes San Francisco Bay, shows a long term steady, even rise across the century with about a 6 inch rise in Relative Sea Level. An eyeball analysis shows what appears to be a leveling off of RSLR, not much happening, since the 1980s.
Snay et al. (2007) examined Vertical Land Movement (VLM) from Continuously Operating GPS Stations (see NOAA CORS) for San Francisco (underlined in yellow, but still hard to see) and determined that the Tide Gauges show a long-term trend of 2.13 mm/year in RSLR (relative sea level rise) and a 1.3 mm/year trend in Absolute SLR (how much the surface of the sea is actually rising), the difference being the 0.83 mm/year of downward vertical land movement (land sinking). At this rate, RSLR would amount to an additional 6.7 inches (about 170 mm) by 2100.
Want a more recent analysis? Again, from NOAA just above, in 2013, based on a 150 year record, Mean Sea Level Trend (relative) is 2.01 mm/yr, taking into account a negative VLM (downward) of 0.36 mm/year. Again, 80 years of 2.01 mm/yr will bring 161 mms of SLR or about 6.3 inches by 2100.
In keeping with the previously shown records, NOAAs Tides and Currents service for San Francisco shows the same long steady tiny rise of 1.96 mm/year, since the “datum shift” caused by the 1906 Great San Francisco Earthquake.
In the San Francisco Bay, at Alameda Air Station, we see:
What are we not seeing in this data? We are not seeing any acceleration of sea level rise in the San Francisco Bay area.
Future Sea Level Rise in San Francisco
What does the IPCC actually project for global sea level rise over the next 80 years, to 2100?
This graph (above) from the Fourth Assessment Report (2007) shows a maximum projection for global sea level rise of 500 mm — one half a meter or about one and a half feet. This projection is three times the actual RSL rise in San Francisco over the latest century.
The IPCC upped the ante (above) in the Fifth Assessment Report . Making a projection specifically for San Francisco (among other cities) with its infamous RCP8.5 gives a likely spread ranging from less than 0.4 meters to almost 1 meter — or 1.4 to 3 feet. RCP8.5 is considered by many to be improbable and by some to be impossible.
Forbes magazine published (June 2018) an article by Earl J. Ritchie of the University of Houston, titled “Is the IPCC Wrong about Sea Level Rise?” in which he concluded that a “rise greater than 1 meter in this century is highly unlikely”.
Satellite altimetry pegs SLR in a range from 2.6mm/yr to 3.4 mm/yr. As of today, NOAA says 2.9 ± 0.4 mm/year. Even the higher estimate only gives us globally 272 mm by 2100, or about 11 inches.
Oft Repeated — but FALSE — meme:
“The pace of global sea level rise nearly doubled from 1.7 mm/year throughout most of the twentieth century to 3.1 mm/year since 1993.”
This statement conflates the long-term tide gauge record with the satellite altimetry data. Global long-term tide gauge data still shows sea level rise in the 1.7-2.0 mm/yr range. Tide gauge data does not show 3.1 mm/yr since 1993. Satellite altimetry shows 3.1 mm/yr since 1993 (actually, current satellite rate is 2.9 mm/yr).
So, where in the world could this 7 to 10 feet “expected sea level rise” come from?
One source of higher projections of sea level come from a single report, Bamber et al. (2019), edited by Stefan Rahmstorf. [Note that, Rahmstorf “is a co-founder of the blog Real Climate”]. The report is not a study of measured sea level rise nor is it a study of measured ice sheet contributions to sea level rise. Instead, it is a type of consensus report, a report of combined “structured expert judgement”, about projected future ice sheet contributions to Sea Level Rise from 22 experts. The report was not peer reviewed but rather accepted for publication by PNAS Editorial Board Member Hans J. Schellnhuber. [ Note that Schellnhuber is on record as stating in 2017, that unless climate action is taken by 2020, the world “may be fatally wounded.” ] Their published conclusion (of their structured expert judgement exercise) was:
“We find it plausible that SLR could exceed 2 m by 2100 for our high-temperature scenario, roughly equivalent to business as usual.”
[ Note that when they say “business as usual” they mean RCP8.5, specifically a 5°C temperature rise by 2100. They pre-qualify the above with this caveat: ]
“Limiting attention to the likely range, as was the case in the Intergovernmental Panel on Climate Change AR5, may be misleading and will likely lead to a poor evaluation of the true risks.”
Journal reference: PNAS, DOI:10.1073/pnas.1817205116
Readers can make of this report what they wish. It may be highly biased and may be intentionally so, intended to attempt to pressure governments to act on global CO2 emissions.
In NOAA Technical Report NOS CO-OPS 083 “GLOBAL AND REGIONAL SEA LEVEL RISE SCENARIOS FOR THE UNITED STATES” (2017) we find the following projections made specifically for the coastal management Sea Level Rise Viewer.
In this chart from that report, we see that in 2012, Parris et al. pegged the highest likely SLR at 2.0 meters, or 6.6 feet.
Five years later, Sweet et al. produce another report for the same purpose, NOAA Technical Report NOS CO-OPS 083 — GLOBAL AND REGIONAL SEA LEVEL RISE SCENARIOS FOR THE UNITED STATES. [Sweet (2017)].
Even when extended upward to take into account the long-tail probabilities of Antarctic melting, the maximum Global Mean SLR is 2.5 meters (8.2 feet).
How improbable are those probabilities?
The stated probability of a 2.5 m rise in global sea level by 2100? 0.1% or in plain numbers a probability of 0.001 — one in one thousand. This is, of course, at very best, a guess — that is, it is no more scientifically valid than any other guess and means simply that it is not considered absolutely impossible.
And Bamber et all their experts?
And Silicon Valley?
Silicon Valley, circled in red on the map, generally refers to the Santa Clara Valley area, which includes Santa Clara County, stretching from Menlo Park to San Jose, but as an economic ecosystem, it can be said to include much of the western shore of the San Francisco peninsula on San Francisco Bay, the city of San Francisco (top left) and its suburbs and perhaps up the eastern Bay Shore from San Jose north to Oakland.
And there’s the rub…the topo/contour map of the southern bay shows that much of the land in the southern-most end of the bay is not only low-lying — but like much of the inundation-prone portions of other cities (Miami and Los Angeles), there are areas virtually at sea level (MHHW can flood these areas) made up of dikes and canals, with the land (in quotes, it is not real land] in narrow strips a foot or two above the tides. Silicon Valley is on the western shore of the bay, stretching from the bridge in the middle of the image south to the city of San José, at the bottom.
It will be apparent, in the next image, that much of this very low-lying ground along the Bay is already classified as nature preserves, designated wetlands, ecological reserves, National Wildlife reserves, or otherwise left to flood with the tides. The animation shifts from a street map view to a satellite photo.
So, that 7 to 10 feet?
It comes from the “Sea Level Rise Viewer – NOAA Office for Coastal Management”. The purpose of this tool is to help local communities plan for possible future sea level rise and storm surge by showing them various scenarios of what areas would be inundated by how much rise in water levels. It is a worthy project, in my opinion. The coastal Georgia barrier island, Tybee Island, has put it to good use in formulating the “Tybee Island Sea-Level Rise Adaptation Plan”.
Looking at what the Sea Level Rise Viewer has to say about San Francisco and Silicon Valley:
This animation starts with current Mean High High Water (the mean of the higher of the high tides seen today). Green areas on the map are areas that are “low-lying” — meaning already flooding at higher tides — these are wetlands etc. The animation then runs through Intermediate, Intermediate High, High, and Extreme scenarios. The last frame shows inundated areas in pink for contrast. (Yes — I’ve skipped the Intermediate Low scenario — I’ll show it later on).
There it is, at the Extreme scenario — 10.2 feet — flooding much of the coasts of Silicon Valley on the bay.
Puzzled by the figure of 10.2 feet, I queried NOAA’s Office of Coastal Management and received this answer:
“The 2.5m from the Sweet et al, 2017 report is global sea level rise. The regional scenarios from the report are based on both a 1 degree grid and at NOAA tide gauges. So for each tide gauge, there is a Regional Scenario computed that includes the following factors
1.) global sea level rise – so for extreme it would be 2.5m
2.) regional oceanographic variation (ex. El Nino, PDO, ADO)
3.) ice sheet mass loss gravity redistribution
4.) vertical land motion.
So for your example. in San Francisco. the extreme is 10.2 FT or 3.11 meters (make sure you click on ft/meters button on bottom of slider) this is higher that the global 2.5m due to 2-4 variables above…most of which is vertical land motion which for that NOAA gauge is -0.00023 ft/year [ 0.07 mm/yr – kh ]
the vertical land motion and other factors make the local / regional SLR scenarios higher or lower. In places where land is rising (ex. AK) sea level is actually projected to go down, even though globally it is rising. The extreme case for local SLR being higher than global rate is Grand Isle, LA … Extreme by 2100 is 3.78m.
Hope this helps, Another place to read about these scenarios is NCA4 CSSR – Chapter 12. https://science2017.globalchange.gov/chapter/12/ 12.5.4 describes the regional projections. “
They take their Ice Sheet Mass loss, not from measurements (no measurements of the future) but from the “structured expert judgement” of Bamber et al. (2019) and add that on top of the 2.5 meters projection from Sweet (2017) and, throw in some for Vertical Land Movement (San Francisco is sinking the tiniest bit every year). They cannot predict El Niño, La Niña, PDO, or ADO out to 2100 — so that bit is questionable — maybe they do it in the decadal projections.
We must allow them to make these Extreme scenario projections for some coastal planning purposes. For instance, if your locality is planning on building a sea side nuclear power plant (say in San Mateo or Alameda Air Station (across the Bay to the east from San Francisco) then it had better pay attention to these projections. I would think that a mere 10.2 feet would be far too close to sea level for safety and would say that double or triple that would be a better safety margin. Even a hospital or sewage plant would need to be minimally at the extreme projection to account for storm surge, tsunamis and other episodic events.
Even though we should make planning allowances for such extreme projections, they should not be considered “expected” quantitative projections of sea level rise. The extreme scenarios, like the IPCC’s RCP8.5, are highly improbable, bordering on physically impossible.
Here is what the probable Sea Level Rise future looks for the San Francisco Bay:
Sea Level Rise is an ongoing Modern Scientific Controversy — the science itself is uncertain and opinions are polarized, both scientifically and politically. Projections for the future are highly uncertain. This essay includes some of my personal opinions — hopefully I have indicated them clearly. All reports in the mass media and many journals (including this essay) should be considered biased and your critical thinking skills should be turned up to Maximum.
The long-term tide gauge sea level trends are currently our most reliable measurements of Regional and Global Sea Level change. Individual tide gauge records represent only Relative Sea Levels until they are coupled to a CGPS@TG (same structure) to correct for Vertical Movement of the tide gauge itself. [ ref: Bevis (2002) “Technical Issues and Recommendations Related to the Installation of Continuous GPS Stations at Tide Gauges” ] Global long-term tide gauge data currently shows sea level rise in the 1.7-2.0 mm/yr range.
There is no real-world difference between the Tide Gauge GMSL Trend of 1.7-2.0 mm/yr and the Satellite GMSL Trend of 2.9 mm/yr. In the 81 years remaining until 2100, the Tide Gauge Trend will equal about 162 mm or 6.4 inches while the Satellite Altimetry Trend will equal 239 mm or about 9.2 inches, the difference of < 3 inches is trivial.
Localities that are concerned about future SLR values below 2.5 meters (~ 8 feet) already have sea level problems that need to be solved and solved in this generation. Remember, Tropical Storm Sandy brought 13 feet of storm surge to New York City. Many US coastal cities are currently in trouble if they get as little as 1 meter (3 feet) of SLR. These quantitative values (1 to 2.5 meters) for future sea level are very real and very possible when allowing for episodic events like hurricanes, tropical storms, tsunamis and seiches.
San Francisco Bay will not see 10.2 feet of SLR by the year 2100. However, Facebook, Tivo, Yahoo and Symantec headquarters should be prepared for episodic flooding by the turn of the century.
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Sea Level Rise is the new Polar Bear Scare for those who promote Catastrophic Climate Change, Climate Crisis, Climate Emergency and the Green New Deal. We should not let the misuse of information and projections about Sea Levels and their rise or fall by some for propaganda purposes blind us to the real-world problems that many low lying sea side localities face.
The seas are not all warm cuddly beaches to visit on our honeymoons. Earth’s seas are huge energetic masses of water churned by chaotic forces mostly beyond our comprehension and on time scales from centuries down to minutes. Many of us have been out on the seas in conditions that try men’s souls.
Sea Level Rise is not a joking matter nor is it an impending disaster. It is simply a fact of life for those living at its edges.
My recommendation for those wishing to keep up with the topic is to read Dr. Judith Curry’s recent paper and related blog post: “Special Report – Sea Level Rise” and “Sea Level Rise: what’s the worst case?”.
Address comments to “Kip…” if speaking to me.
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