Is Coastal Hardening an mCDR Opportunity?
Michael Hayes
Bruce Melton -- Austin, Texas
The Coastal Spine will likely fail miserably. The US Army Corp of
Engineers does not take anything more than IPCC low end SLR into
consideration. The Texas Sierra Club and every environmental
organization locally does not support this project.
B
This is the results of the 2018 Army Corp dune restoration on
Follet Island, Surfside Beach, immediately south of Galveston
Island across San Luis Pass. The restoration lasted less than a
year. To add insult to injury, the Corp used a clay-based soil to
restore, with the assumption that it would erode less than beach
sand. What has happened is that the clay has eroded and has now
mixed in with the beach sand and forever changed the evolutionary
boundaries of this beach.
Director, Climate Change Now Initiative, 501c3
President, Melton Engineering Services Austin
8103 Kirkham Drive
Austin, Texas 78736
(512)799-7998
ClimateDiscovery.org
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MeltonEngineering.com
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Michael Hayes
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Bruce Melton -- Austin, Texas
Good ideas Michael. But climate change is now in a different mode
with tipping collapses activated. The sea level rise rate in the
western Gulf is 10 mm per year averaged over the last 10 years and
this will only increase nonlinearly and rapidly with very large
inundation and C emissions in areas not protected by the Coastal
Spine (except the Coastal Spine will not be completed in 10
years...). Doglegging the spine to keep out end around flooding
will be easy. Armoring the big dune barrier is also easy though
any sea level rise over a foot or two eliminates the coastal zone
and creates quite large C emissions. Chronic tidal flooding will
lead to the onset of significant coastal resource abandonment in
about ten years as per NOAA and the Union of Concerned Scientists
though at the rate we are increasing the rise trend it may be
sooner. The average sea level rise across all lower 48 NOAA gauges
in 2019 was 1.5 inches or 38 mm. The maximum adaptability rate is
3 feet per century, meaning there is not enough money to adapt, so
abandonment costs will rapidly overwhelm the global economic
buffer capacity.
Most adaptation strategies are dependent upon restoration because of global economic stress. What we have to do is prioritize a restoration goal, lowering 1.5 C to 1 C or less, completing restoration by mid-century so as to avoid these tipping collapse nightmare scenarios that are now active when they were not supposed to activate until 5 C warming (Lenton 2019). This will allow adaptation measures already needed to be successful. Otherwise global economic collapse will make all moot.
Below I have included the sea level rise citations and summaries from the notes on a couple of slides in my upcoming learning tool, An Introduction to Advanced Climate Change.
Steep trails,
B
Rapid Acceleration of Sea Level Rise on the US East and Gulf Coasts From Slow Down of Gulf Stream... from Yin 2023, "Both the century-long tide gauge data and the more recent altimetry data reveal a rapid decadal acceleration of SLR during 2010-2022 along the U.S. East Coast and the Gulf of Mexico coast. The acceleration is most notable on the Southeast and Gulf Coasts, as quantified by the decadal rise rate, extreme annual sea level departure from the long-term trend, as well as the sea level record-breaking frequency and magnitude. Our analysis suggests that this SLR acceleration is largely a lagged response to the observed slowdown of the Atlantic meridional overturning circulation in 2009-2010."
Yin, Rapid Decadal Acceleration of Sea Level Rise along the U.S. East and Gulf Coasts during 2010-2022 and Its Impact on Hurricane-Induced Storm Surge, Journal of Climate, March 2, 2023.
Full - https://journals.ametsoc.org/view/journals/clim/aop/JCLI-D-22-0670.1/JCLI-D-22-0670.1.xml
NOAA Press Release - https://cpo.noaa.gov/News/ArtMID/7875/ArticleID/2820/Rapid-Sea-Level-Rise-along-the-US-East-and-Gulf-Coasts-during-2010-2022-and-Its-Impact-on-Hurricane-Induced-Storm-Surge
Sea level rise rate of 10 mm per year over the last decade exceeds model predictions from Cape Hatteras to the Western Gulf of Mexico... Dangedorf 2023 tells us sea level rise rates on the US East Coast from Hatteras to the western Gulf of Mexico of 10 mm per year over the last decade exceed climate model projections. They find internal variability and external forcing are the cause, and will likely return to within future modeling projections within the next decade or so. However, they authors state, "Our results imply that the early detection of acceleration signals, which are needed for near-term planning and decision-making, still represents a major challenge and that comparisons with climate model projections, specifically locally, need to be undertaken with care. More generally, our findings highlight the critical role of a mechanistic understanding of MSL accelerations at the regional scale and its importance for sea-level projections."
Dangedorf et al., Acceleration of U.S. Southeast and Gulf coast sea-level rise amplified by internal climate variability, Nature Communications, April 10, 2023.
https://www.nature.com/articles/s41467-023-37649-9
The sea level rise rate has increased 750 percent since 1900, mostly since 2000…The World Meteorological Organization tells us in their State of the Global Climate 2021, sea level is now rising at 4.5 mm per year. Columbia University's Sea Level Rise Page tells us that 1900 to 1930 sea level rise was 0.6 mm per year, a 750 percent increase. with most of the increase happening since the turn of the twenty-first century.
State of the Global Climate 2021, World Meteorological Organization, May 2021.
https://public.wmo.int/en/our-mandate/climate/wmo-statement-state-of-global-climate
Columbia University's Sea Level Rise Page.
http://www.columbia.edu/~mhs119/SeaLevel/Dynamical Ice
Sheet collapse is not
included in sea level rise projections of the IPCC (Technical
Summary)…
“Based on current understanding, only the collapse of
marine-based sectors of
the Antarctic ice sheet, if initiated, could cause GMSL to
rise substantially
above the likely range during the 21st century.” The likely
range for RCP8.5 by
2100 is 0.63 meters, or two feet.
IPCC 2013, Scientific Basis
Technical Summary, page 49.
http://www.climatechange2013.org/images/report/WG1AR5_ALL_FINAL.pdf
Sea level rise
projections Core Report AR5 IPCC, no ice sheet collapse
included… IPCC
has caveated ice sheet collapse out of their sea level rise
projections since
the first report and this continues today with their
worst-case scenario of
0.98 m (3.2 feet) SLR by 2100 and 3 m (9.8 feet) not projected
until 2300. Page
1182 and 1188.
Chapter 13, IPCC Fifth Report, Scientific
Basis, 2013
https://archive.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_Chapter13_FINAL.pdf
IPCC Fifth Assessment Report, Sea level Rise - Ice Sheet Collapse Not included… “Literature investigating the relation between the SLR generated by dynamical change and emission scenario does not currently exist. There is also a lack of literature on the relation between emission scenario and the intrusions of warm water into ice-shelf cavities thought to be important in triggering observed mass loss (Jacobs et al., 2011) and potentially important in the future (Hellmer et al., 2012). It is therefore premature to attach a scenario dependence to projections of dynamical change, even though such a dependency is expected to exist."
Page 1174, paragraph 4… " In summary, it is likely that dynamical change within the Antarctic ice sheet will lead to SLR during the next century with a range of –20 to 185 mm. SLR beyond the likely range is poorly constrained and considerably larger increases are possible (the underlying probability distribution is asymmetric towards larger rise), which will probably be associated with the MISI (Box 13.2). Although the likelihood of such SLR cannot yet be assessed more precisely than falling above the likely range, literature suggests (with medium confidence) that its potential magnitude is several tenths of a metre. We are unable to assess SLR as a function of emission scenario, although a dependency of SLR on scenario is expected to exist. In addition, coupling between SMB and dynamical change is likely to make a further contribution to SLR of 0 to 35% of the SMB. All the available literature suggests that this dynamical contribution to sea level rise will continue well beyond 2100."
Summary – page 1174,
paragraph 9… "
In summary, ice-dynamics theory, numerical simulations, and
paleo records
indicate that the existence of a marine-ice sheet instability
associated with
abrupt and irreversible ice loss from the Antarctic ice sheet
is possible in
response to climate forcing. However, theoretical
considerations, current
observations, numerical models, and paleo records currently
do not allow a
quantification of the timing of the onset of such an
instability or of the
magnitude of its multi-century contribution.“
IPCC Fifth Assessment Report (AR5), Scientific Basis, Chapter
13, Sea Level
Change, page 1173
https://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_Chapter13_FINAL.pdf
NOAA - 1.5 inches (38 mm) sea level rise average in 2019 at all US lower 48 NOAA tide gauges... This new record, arguably influenced y natural variation, is 1.5 inches in a single year (38 mm). This single year record doubles the old record and is ten times greater than the long-term global average rate.
Page 3 and 4
"In 2019 (12) the national (median) HTF [high tide flooding]
occurrence
along U.S. coastlines as a whole was 4 days. This is 1 day
less than the record
reached in 2018 as measured by 98 NOAA tide gauges (13)
(Figure 3a). Assessed over
several decades, the national trend in HTF frequency is
accelerating, and HTF
is more than twice as likely now as it was in 2000. The rapid
growth is in
response to RSL rise, which is occurring along most U.S.
coastlines. (Our study
does not include Alaska, where land-based ice melt is
contributing to land
rebound (14)). In 2019, RSL along U.S.
coastlines
(median value) reached an all-time record of 0.34 m since 1920
(last 100
years), which is about 4 centimeters (1.5 inches) higher than
it was in 2018. The
national RSL (linear) trend along U.S. coastlines examined
here is 2.8
millimeters/year over this period (not shown). Inherent to the
RSL measurement
in Figure 3a is the effect of land subsidence, which
nationally (median plus or
minus standard deviation value of the 98 tide gauges
monitored) is occurring at
a rate of 0.7 ±1.4 mm/year, but can be as high as 7 mm/year
along the coastline
of Louisiana (Zervas
et
al., 2013; Sweet et al., 2017). Annual mean RSLs
at most East and
Gulf Coast tide gauges (57 of the 62) broke their historical
records (Figure
3b) in 2019 by (median value) 2.6 cm (about 1 inch)." [emphasis
added]
Press Release - NOAA, U.S. high-tide
flooding continues to
increase, July 14, 2020
https://www.noaa.gov/media-release/us-high-tide-flooding-continues-to-increase
New NOAA Technical Report on high tide flooding:
NOAA 2019 State of U.S. High Tide Flooding with a 2020
Outlook, TR 092, July
2020, page 3 and 4.
https://tidesandcurrents.noaa.gov/publications/Techrpt_092_2019_State_of_US_High_Tide_Flooding_with_a_2020_Outlook_30June2020.pdf
https://oceanservice.noaa.gov/aa-updates/high-tide-flooding-outlook-072320.html
NOAA Sweet 2017, Global and Regional Sea Level Rise Scenarios for the United States
14"
sea level
rise by 2030, intermediate-high scenario (not extreme
scenario)… NOAA
defines this rate of tidal flooding as when the 5-year tide
becomes the tide
that happens five or more times per year. "The median value in
Figure 15d is about 0.35 m, with a
range from about 0.1 m to 1.1 m. Thus, for most of U.S. tide
gauge locations
examined (108 locations; 90 along U.S. coastlines outside
Alaska), with an
additional 0.35-m rise (<14 in) in RSL, exposure to
disruptive/damaging
tidal flooding will become much more commonplace." ...
"Considering RSL under the Low, Intermediate-Low,
Intermediate and Intermediate-High scenarios (Figure 16a–d),
disruptive/damaging tidal flooding will occur five or more times
a year at most
locations (90 cities) along the U.S. coastline (outside Alaska)
by or about (±5
years) 2080, 2060, 2040 and 2030, respectively." ...
NOAA
13.1 feet of Sea
Level Rise by 2100 (100-year GMSL (Global Mean Sea Level), or
the normal annual
tide with a one-percent chance of occurrence)… By 2070,
the one-percent mean sea level (100-year event) is
projected to be 7.8 feet higher than today. By 2100, NOAA
projects the ocean
could be as much as 13.1 feet higher. This is for Key West and
not radically
dissimilar for much of the rest of the US. (Figure 17, page
40)... "The Low scenario has a 94% to 100% chance of being
exceeded under RCP2.6 and RCP8.5, respectively, whereas the
Extreme scenario
has a 0.05% to a 0.1% chance of being exceeded. New evidence
regarding the
Antarctic ice sheet, if sustained, may significantly increase
the probability of the Intermediate-High, High, and Extreme
scenarios, particularly for RCP8.5 projections based upon Kopp
et al. (2014). These ice-sheet modeling
results have not yet been incorporated into a (conditional)
probabilistic analysis of GMSL." (page
21)
Sweet et al., Global and Regional Sea Level Rise Scenarios
for the United States, NOAA, January 2017.
https://tidesandcurrents.noaa.gov/publications/techrpt83_Global_and_Regional_SLR_Scenarios_for_the_US_final.pdf
Spanger Siegfried et al., When Rising Seas Hit Home, Union of Concerned Scientists, July 2017.
https://www.ucsusa.org/sites/default/files/attach/2017/07/when-rising-seas-hit-home-full-report.pdf
BEACH AND WETLAND
DISINTEGRATION
THRESHOLD - 5 mm PER YEAR
US Climate Change Science Program shows the beach and wetland disintegration threshold is 5 to 7 mmm per year on low slope beaches and barrier islands…
Scenarios Evaluated (page XV) – Barrier island disintegration and wetland loss defined by Figures ES1 and ES2
Scenario 1 - 20th century rate is 3 to 4 mm per year on the Mid-Atlantic Coast
Scenario 2 - 20th century SLR rate plus 2 mm per year: moderate beach erosion, wetlands conversion to open water, and unrecoverable barrier island disintegration.
Scenario 3 - 20th Century SLR rate plus 7 mm per year: Widespread, almost total beach erosion, wetlands conversion to open water and unrecoverable barrier island disintegration.
Interpretation: In 2009, the US Global Change Research Program report, Coastal Sensitivity to Sea Level Rise, Focus on the Mid-Atlantic Region, identified that most of the low-profile beaches and coastal wetlands along the mid-Atlantic coast were already eroding and being degraded by sea level rise beyond the threshold of beach and wetlands regeneration, with 3 to 4 mm of sea level rise per year. This report defines the impacts of three scenarios of sea level rise rate: 20th century rate, 20th century plus 2 mm per year and 20th century plus 7 mm per year.
Global Relevance - Because coastal barrier islands around the world are quite similar, degradation and disintegration behaviors can be assumed to be similar.
Figure ES1, page 3 and ES2, page 4 illustrate the beach degradation and wetland submergence scenarios from this report. Geographic extents include North Carolina through New York. The following is a summary of conditions shown in these two figures:
-- Existing conditions in 2009: 3 to 4 mm sea level rise, about 90% of beaches are being degraded by overwash, erosion and island breaching. A threshold condition may already exist for the most vulnerable category where barrier island segmentation and disintegration could be occurring. Five percent of existing wetlands have been converted to open water and 15 to 20% could be threatened.
-- With 2 mm additional sea level rise or 5 to 7 mm rise per year, thresholds condition develop for barrier island segmentation and disintegration on about 25% of barrier islands and could develop across another 25%. Existing wetlands converted to open water increases to 15 to 20% and an additional 80 percent could be threatened.
-- With 7 mm additional sea level rise, or 10 to 11 mm of sea level rise per year, thresholds condition develop for barrier island segmentation and disintegration on about 60% of barrier islands and could develop across another 30%. Existing wetlands converted to open water increases to 85% and an additional 5 % could be threatened.
Low-profile beach geometry is similar for most of the Gulf and East Coasts, so this document can serve as a guide to current and future sea level rise degradation of beaches and wetlands along most of the heavily populated US coast, because most of the US coast -by mileage- consists of low profile beaches. (Heavily populated excludes Alaska, and Louisiana is a special case.)
Climate Change Science
Program 2009,
Coastal Sensitivity to Sea Level Rise - Focus on the
Mid-Atlantic Region,
Washington, DC: US Environmental Protection Agency.
https://www.globalchange.gov/sites/globalchange/files/sap4-1-final-report-all.pdf
MAXIMUM ADAPTABLE SEA LEVEL RISE RATE
Adaptability limit
to SLR of three
feet per century… The
sea level rise adaptability limit, from the IPCC Working Group
II Report 2014,
“Nicholls et al. (2011) show that only a limited number of
adaptation options
are available for specific coastal areas if sea level exceeds
a certain
threshold (1 m) at the end of the century.”
Climate Change 2014: Impacts, Adaptation, and Vulnerability.
Part A: Global and
Sectoral Aspects. Contribution of Working Group II to the
Fifth
Assessment Report of the Intergovernmental Panel on Climate
Change, page 393,
paragraph 10.
https://www.ipcc.ch/site/assets/uploads/2018/02/WGIIAR5-Chap5_FINAL.pdf
Base
document for 3 feet sea level rise adaptation limit in 100
years…
Nichols et al., Sea-level rise
and its
possible impacts given a beyond 4C world in the twenty-first
century, Phil
Trans Royal Society, 2011.
ResearchGate (Free Subscription required) https://www.researchgate.net/publication/49643248_Sea-level_rise_and_its_possible_impacts_given_a_'beyond_4_degrees_C_world'_in_the_twenty-first_century
One meter per
century for marshes,
(10 mm per year)…
Kirwan et al., Limits on the adaptability of coastal marshes
to rising sea
level, Geophysical Research Letters, December 2010.
https://www.researchgate.net/publication/228888170_Limits_on_the_adaptability_of_coastal_marshes_to_rising_sea_level
Australia, 1 meter
max…
Cooper et al., Extreme sea-level rise and adaptation options
for coastal resort
cities: A qualitative assessment from the Gold Coast,
Australia, Ocean and
Coastal Management, August 2012 (Abstract Only).
http://www.sciencedirect.com/science/article/pii/S0964569112000701
SEA LEVEL RISE
PROJECTIONS OF
IMPACTS AND COSTS
From
the Fourth National
Climate Assessment 2018:
Coastal US GDP is
about 45 percent
of total US GDP… The
gross domestic product (GDP) for the category Shore Adjacent
Counties, is $7.2
trillion in annual US GDP, out of $16.7 trillion total for the
US (43 percent).
For the Coastal Counties category, this is $8 trillion in
annual GDP out of
$16.7 trillion (48 percent).
(NCA 2018, National Ocean Economics Program 2016 update, Table
8.1 page
326)
Roads
in the US coastal zone; 60,000 miles… "There are more than
60,000 miles of
roads and bridges in the coastal floodplains already
demonstrably vulnerable to
extreme storms and hurricanes."
(NCA 2018, FHWA 2018. Page 326, par 3)
Over
133 million lived in the coastal zone in 2018, 43 percent of
the US population…
"As
of 2013, coastal shoreline counties were home to 133.2 million
people, or 42%
of the population." (NCA 2018, National Ocean Economics
Program 2016
update, page 326, par 2)
IPCC low and
intermediate sea level
rise of about 20 inches by 2100 will create large economic
losses in coastal
areas creating cascading economic impacts… "[T]here is medium
confidence that
many coastal communities will be transformed by 2100 under any
scenario and
that many individuals will be financially devastated under
lower emission
scenarios (RCP4.5 or RCP2.6). Considering current exposure of
assets and the
latest SLR science, large economic losses in coastal regions
that will generate
cascading impacts to the overall economy of the United States
are considered to
be likely.“ IPCC Assessment
Report 5
projects about 0.5 meter (about 20 inches) of sea level rise
for the low and
intermediate scenarios RCP2.6 and RCP 4.5.
National Climate Assessment 2018, Part 2, Our Changing
Climate.
https://nca2018.globalchange.gov/downloads/NCA4_2018_FullReport.pdf
IPCC 2013 The Physical
Science Basis
WG1AR5_ALL_FINAL, Chapter 13, Table 13.5, page 1182.
https://www.ipcc.ch/report/ar5/wg1/
$27 trillion per
year damages from
sea level rise with less than three feet rise per year in
2100...
If
the 2 C target is missed, and we follow the RCP8.5_J14
scenario (median sea
level rise of 0.86m and 95th percentile of 1.8m in 2100),
global annual flood
costs without additional adaptation are projected to be US$
14.3 trillion per
year (2.5% of GDP) for the median scenario and up to US$ 27.0
trillion per year
for the 95th percentile (figure 4(a)), accounting for 4.7% of
global GDP (table
S4).
Jevrejeva
et
al., Flood damage costs under the sea level rise with warming
of 1.5 and 2C,
Environmental Research Letters, July 4, 2018.
http://iopscience.iop.org/article/10.1088/1748-9326/aacc76/pdf
UNRECOVERABLE RESOURCE ABANDONMENT BY 2035
Unrecoverable
resource abandonment
by 2035, NOAA and the Union of Concerned Scientists…
NOAA's 2017 Sea level rise report tells us that we can expect
9 inches of sea
level rise by 2030. The Union of Concerned Scientists report
on the NOAA’s
findings tells us that with 9 inches of sea level rise, we
will see resource
abandonment as chronic nuisance flooding increases 25 times.
This amount of sea level rise increase will create conditions where normal high tide nuisance flooding of 0.5 m more than the normal high tide, with 9 to 14 inches of sea level rise by 2030 under the worst-case scenario, increases in frequency from once every five years to once every 2.4 months, on average.
UCS, Spanger Siegfried 2017, "Within 20 years, by 2035, nearly 170 coastal US communities —roughly twice as many as today— will reach or exceed the threshold for chronic inundation, given moderate sea level rise… “
UCS, Spanger Siegfried 2017 by 2035, “moderate sea level
rise,” from page 11,
Figure 3, is 0.75 meters above 1992.
UCS summary page - https://www.ucsusa.org/resources/when-rising-seas-hit-home
Sweet et al., Global and Regional Sea Level Rise Scenarios for
the United
States, NOAA, January 2017.
https://tidesandcurrents.noaa.gov/publications/techrpt83_Global_and_Regional_SLR_Scenarios_for_the_US_final.pdf
Spanger
Siegfried et al., When Rising Seas Hit Home, Union of
Concerned Scientists,
July 2017.
https://www.ucsusa.org/sites/default/files/attach/2017/07/when-rising-seas-hit-home-full-report.pdf
"There comes a
threshold of
sea level rise-induced flooding that makes normal routines
impossible and
drives hard choices." … "UCS defines flooding
that occurs 25
times per year (on average, once every other week) or more as
'chronic
inundation' [or] any coastal community that experiences this
frequency of
flooding over 10 percent or more of its land area, excluding
wetlands and areas
protected by federal levees."
(Union of Concerned Scientists (UCS), When Rising Seas Hit
Home, 2017, quote
box and par 5.)
Spanger
Siegfried et al., When Rising Seas Hit Home, Union of
Concerned Scientists,
July 2017.
https://www.ucsusa.org/sites/default/files/attach/2017/07/when-rising-seas-hit-home-full-report.pdf
Director, Climate Change Now Initiative, 501c3
President, Melton Engineering Services Austin
8103 Kirkham Drive
Austin, Texas 78736
(512)799-7998
ClimateDiscovery.org
ClimateChangePhoto.org
MeltonEngineering.com
Face...@Bruce.Melton.395
Inst...@Bruce.C.Melton
The Band Climate Change
Twitter - BruceCMelton1