Archives par mot-clé : Sea level

climate-debate

With Sea-Level Rise, Climate Science Meets Reality

by J. Weatherall, August 6, 2019 in ClimateChangeDispatch

…

Numerous satellites utilized by Australian agencies and research bodies are able to take a measure of sea level by way of an altimeter. However, according to the CSIRO, it should not be overlooked that the signal to do so requires

# A satellite in an orbit which repeats the same ground track very closely (within about 1 kilometer)

# A radar system to measure the distance from the satellite to the sea surface to high accuracy. TOPEX/Poseidon and Jason-1 use two radar frequencies, Ku band (13.6GHz) and C band (5.3Ghz).

# A tracking system capable of locating the satellite vertically at any time to within a few centimeters. Some of the components of such a system are:

1/ Systems (usually a combination of GPS, satellite laser ranging and the French DORIS system) to locate the satellite

2/ A high-quality gravity model

3/ A model of the drag from solar wind and the atmosphere

4/ Suitable software to combine all of the above

Other corrections to correct the range:

On the satellite:

1/ A water vapor radiometer to measure the amount of water vapor between the satellite and the sea surface (the water vapor slows down the radar pulse, causing the raw measurement to be too long)

2/ Measurement of the range at two frequencies to estimate the “ionospheric correction” — that is, the degree to which the radar pulse is slowed down by free electrons in the ionosphere

3/ The troughs of waves contribute more to the radar reflection than the crests, so we need correction for this. This is estimated from the wind speed and the wave height, both of which can be estimated from the characteristics of the returned radar pulse.

On the ground:

1/ Ocean tide models to convert the raw altimeter measurement to “de-tided”

2/ Estimates (from a model) of the atmospheric pressure. This is used to calculate a correction to the radar range to compensate for the atmosphere slowing down the radar pulse

3/ A correction for the “inverse barometer” effect, where sea level is depressed in areas of high atmospheric pressure, and vice versa.

No one besmirches the accomplishments of the engineering and technology involved.

However, it is a basic truism that the greater the number of separate corrections needing to be applied, the greater the risk of miscalculation.

…

 

climate-debate

Study: Pacific Islands Will Survive Climate Change

by Eric Worrall, July 17, 2019 in WUWT

Who could have imagined that islands which survived rapid sea level rise at the end of the last ice age have no problem coping with changes in sea level?

Media Release
From: University of Auckland

Pacific atolls can adapt to rising seas and extreme storms – new study

Low-lying Pacific islands in atoll archipelagos such as Tuvalu, Tokelau and Kiribati are likely to adapt to the effects of climate change rather than simply sink beneath the waves, a new study shows.

Tuvalu, Tokelau and Kiribati are widely considered under threat from rising seas and severe storms due to climate change with their residents becoming ‘climate refugees’.

Researchers from the University of Auckland’s School of Environment recreated a scale model of tiny Fatato Island on the southeast rim of Funafuti Atoll in Tuvalu to test the ability of the real island to withstand predicted climate affects.

The study simulated higher sea levels and storm-generated waves up to 4m in a 20m-long water chute or ‘flume’ to replicate real-world sea levels of 0.5m and 1m in a purpose built laboratory at the University of Plymouth in the United Kingdom.

…

A beach at Funafuti atoll, Tuvalu, on a sunny day. Author Stefan Lins, source Wikimedia

climate and geology

The Holocene Sea Level Highstand

by David Middleton, June 6 , 2019 in WUWT

What is a highstand?

A highstand is one phase of the sea level cycle (AAPG Wiki)

  • Rising
  • Highstand
  • Falling
  • Lowstand

The highstand is the maximum sea level achieved during the cycle.

The Holocene Epoch

The Holocene Epoch was recently formally subdivided into three stages:

  1. Greenlandian Stage = Lower or Early-Holocene. 11.70 ka to 8.33 ka
  2. Northgrippian Stage = Middle or Mid-Holocene. 8.33 ka to 4.25 ka
  3. Meghalayan Stage = Upper or Late-Holocene. 4.25 ka to present

The abbreviation “ka” refers to thousands of years ago. Lower, Middle and Upper are generally used when referring to rock-time units. Early, Mid and Late are generally used when referring to time units (Haile, 1987). Prior to the formal subdivision, Lower/Early, Middle/Mid and Upper/Late were commonly used; however there was no formal nomenclature. The fake word, “Anthropocene” is not used by real geologists.

There is also an informal climatological subdivision of the Holocene:

  • Preboreal 10 ka–9
  • Boreal 9 ka–8 ka
  • Atlantic 8 ka–5 ka
  • Subboreal 5 ka–2.5 ka
  • Subatlantic 2.5 ka–present

Source: Wikipedia

Why would there have been a Mid- to Late-Holocene highstand?

…

Figure 1. Holocene sea level curves from Moore & Curray, 1974.

…

climate-debate

Another climate lie bites the dust – No, Honolulu’s beaches aren’t going to disappear in 20 years

by Aylin Woodward, April 25, 201 in WUWT

In May 2017, high tides engulfed parts of the iconic Waikiki beach, edging dangerously close to waterfront hotels. This kind of high-tide flooding, often called a king tide or sunny-day flood, occurs when ocean water surges to higher levels than coastal infrastructure was designed to accommodate. In that case, water levels rose 2.5 feet above average in Waikiki, drowning nearby roads and sidewalks.

According to a 2017 report (which was updated in September 2018), Hawaii’s state capital and Waikiki Beach – along with other coastal strips on Hawaii’s five islands – are expected to experience frequent flooding within 15 to 20 years.

“This flooding will threaten $5 billion of taxable real estate; flood nearly 30 miles of roadway; and impact pedestrians, commercial and recreation activities, tourism, transportation, and infrastructure,” Shellie Habel, lead author of the 2017 study, said in a release.

Now, Hawaii state lawmakers are taking steps to shore up the state’s beaches and coastal cities. A new bill that mandates a statewide shore protection program has passed both houses of Hawaii’s state legislature, and will soon makes its way to the governor’s desk for approval.

All well and good that they want to improve beach resilience. But, the claim that ” Hawaii’s iconic Waikiki Beach could be engulfed by the ocean in 20 years ” is totally bogus.

Here is why:

…

 

climate-debate

Isle de Jean Charles & Sea Level Rise

by P. Homewood, April 20, 2019 in NotaLotOfPeopleKKnowThat

The Isle de Jean Charles, Louisiana. It’s been largely submerged beneath the sea over the last 6 decades. The program gives the definite impression that the main reason for this inundation is sea level rise due to melting ice and thermal expansion of the oceans – driven by man-made climate change. Attenborough does mention oil extraction as a cause but his narrative is lost to the general tone of the messaging that this is a “climate catastrophe” and that the families driven from their homes in this part of Louisiana are some of the world’s first “climate refugees”. This is palpable bullshit.

…

 

https://tidesandcurrents.noaa.gov/sltrends/sltrends.html

climate-debate

CA sea level rise alarmist study ignores 30 years of NOAA data with no coastal sea level rise acceleration

by Larry Hamlin, March 13, 2019 in WUWT

NOAA tide gauge data measurements exist for 17 locations along the California coast with 8 of these locations having actual measured sea level rise data covering periods for more than 70 to 120 years in duration.

This measured data shows that none of these California locations are experiencing coastal sea level rise acceleration since climate alarmist first made such erroneous and flawed sea level acceleration claims before the U.S. Senate in 1988.

Climate alarmists and their supporting media conveniently conceal the fact that their flawed claims have been hyped for the last 30 years as they continue to try again and again to make the same repeated but flawed claims apparently hoping that the public will forget their long track record of failure and exaggeration.

NOAA measured tide gauge data shows that coastal sea level rise at Ca. locations varies between 3 to 12 inches per century and have remained at those levels during the long measurement periods during which actual measured data have been recorded with a sample of that measured data shown below for San Diego, La Jolla, Los Angeles and San Francisco.

…

climate-debate

New Paper: Widespread Collapse Of Ice Sheets ~5000 Years Ago Added 3-4 Meters To Rising Seas

by K. Richard, March 11, 2019 in NoTricksZone

During the Mid-Holocene, when CO2 concentrations were stable and low (270 ppm), Antarctica’s massive Ross Ice Shelf naturally collapsed, adding the meltwater equivalent of 3-4 meters to sea levels.

Because CO2 concentrations changed very modestly during the pre-industrial Holocene (approximately ~25 ppm in 10,000 years), climate models that are predicated on the assumption that CO2 concentration changes drive ocean temperatures, ice sheet melt, and sea level rise necessarily simulate a very stable Holocene climate.

In contrast, changes in ocean temperatures, ice sheet melt, and sea level rise rates were far more abrupt and variable during the Holocene than during the last 100 years.

Modern ocean changes are barely detectable in the context of natural variability

…

Image Source(s): Rosenthal et al., 2013; Climate Audit

…

climate-debate

What’s Natural? Changing Sea Levels – Part 1

by Jim Steele, February 23, 2019 in WUWT

Local sea levels appear to rise when ocean volumes increase, but also when the land sinks. Scientists increasingly warn that coastal cities are sinking much faster than ocean volumes are rising. Pumping out groundwater not only causes lands to sink, it increases the oceans’ volume. China’s Huanghe Delta is sinking 10 inches a year. Southeast Asian cities battle sinking rates of 1.2 to 2.4 inches per year. Regions around Houston, Texas had sunk 10 feet by 1979; a disaster waiting to happen where hurricanes commonly generate 15-foot storm surges. Likewise, New Orleans was doomed by sinking 1.4 inches per year. Built on marshland, San Francisco’s airport sinks 0.4 inches per year.
In contrast, ocean warming plus added glacial meltwater are estimated to have only added 0.06 inches per year to sea level from 1850 to 1990, punctuated by decades that accelerated sea level rise to 0.14 inches a year. Still, that fastest rate of modern sea level rise remains only one-tenth of New Orleans’ sinking rate.

…

climate-debate

A global assessment of atoll island planform changes over the past decades

by E. Duvat, October 25, 2018 in WiresClimateChange

Over the past decades, atoll islands exhibited no widespread sign of physical destabilization in the face of sea‐level rise. A reanalysis of available data, which cover 30 Pacific and Indian Ocean atolls including 709 islands, reveals that no atoll lost land area and that 88.6% of islands were either stable or increased in area, while only 11.4% contracted. Atoll islands affected by rapid sea‐level rise did not show a distinct behavior compared to islands on other atolls. Island behavior correlated with island size, and no island larger than 10 ha decreased in size.

…

climate-debate

Study reconstructing ocean warming finds ocean circulation changes may account for significant portion of sea level rise

by Anthony Watts, January 7, 2019 in WUWT

Study suggests that in the last 60 years up to half the observed warming and associated sea level rise in low- and mid- latitudes of the Atlantic Ocean is due to changes in ocean circulation.

Over the past century, increased greenhouse gas emissions have given rise to an excess of energy in the Earth system. More than 90% of this excess energy has been absorbed by the ocean, leading to increased ocean temperatures and associated sea level rise, while moderating surface warming.

The multi-disciplinary team of scientists have published estimates in PNAS, that global warming of the oceans of 436 x 1021 Joules has occurred from 1871 to present (roughly 1000 times annual worldwide human primary energy consumption) and that comparable warming happened over the periods 1920-1945 and 1990-2015.

…

climate-debate

“Terrifying Sea-Level Prediction Now Looks Far Less Likely”… But “marine ice-cliff instability” is “just common sense”

by David Middleton, January 5, 2019 in WUWT

…

Marine ice cliff instability (MICI) “has not been observed, not at such a scale,” “might simply be a product of running a computer model of ice physics at a too-low resolution,” ignores post glacial rebound, couldn’t occur before ” until 2250 or 2300″… Yet “the idea is cinematic,” “it’s just common sense that Antarctic glaciers will develop problematic ice cliffs” and something we should plan for…

“Our results support growing evidence that calving glaciers are particularly sensitive to climate change.”  Greenland’s climate is always changing… Always has and always will change… And the climate changes observed over the last few decades are not unprecedented. The Greenland ice sheet is no more disappearing this year than it was last year and it is physically impossible for the ice sheet to “collapse” into the ocean.

…

Figure 6. Jakobshavn Isbrae. (Wikipedia and Google Earth)

climate-debate

Sea level oscillations in Japan and China since the start of the 20th century and consequences for coastal management – Part 1: Japan Author links open overlay panel

by Albert Parker, March 1, 2019 in Ocean&CoastalManagement

Highlights
• Japan has strong quasi-20 and quasi-60 years low frequencies sea level fluctuations.
• These periodicities translate in specific length requirements of tide gauge records.
• 1894/1906 to present, there is no sea level acceleration in the 5 long-term stations.
• Those not affected by crustal movement (4 of 5) do not even show a rising trend.
•Proper consideration of the natural oscillations should inform coastal planning.

…

See also here

better to know...?, climate-debate

Land motion drives varying rates of sea level along the US East Coast

by Charles the moderator, December 26, 2018 in WUWT

From Science Magazine

Dec 20, 2018

Along the US East Coast, the Earth’s continued response to the end of the last ice age explains variances in relative sea level rates

Chestnut Hill, Mass. (12/20/2018) – Along the East Coast of the United States, relative sea level change does not happen uniformly between Maine and Florida.

Data have shown that sea level rise in the Mid-Atlantic region surpassed changes in relative sea level along the coastlines of the South Atlantic and the Gulf of Maine. A team of researchers took a look back at historical data through new analytical methods to pinpoint the reason behind the different rates of sea level change.

Assessing data from a range of sources and previous studies, the team concluded that the movement of the earth – referred to as vertical land motion – is the dominant force behind variations in rates of sea level rise up and down the East Coast, the team reports today in the journal Nature.

…

climate-debate

Is the Pacific island nation of Tuvalu growing, and not sinking, as Craig Kelly says?

by RMIT ABC fact Check, December 21, 2018

The claim

Liberal MP and climate sceptic Craig Kelly made headlines in November when he was caught on tape mocking “lefties” for exaggerating the effects of climate change.

Speaking at a local party event, audio of which was leaked to the Guardian, Mr Kelly set out to debunk several justifications for climate change action, including the argument that Tuvalu, the Pacific island nation, was slipping beneath the sea.

“The science tells us that Tuvalu, which I often hear about, is actually growing not sinking,” he told colleagues.

Is Tuvalu growing? RMIT ABC Fact Check investigates.

The verdict

Mr Kelly’s claim checks out.

In the four decades to 2014, Tuvalu’s total land area grew by 73 hectares, or 2.9 per cent.

…

climate-debate

The clever ruse of rising sea levels

by J.  Lehr & T. Harris, December 6, 2018 in WUWT

For the past 50 years, scientists have been studying climate change and the possibility of related sea level changes resulting from melting ice and warming oceans. Despite the common belief that increasing levels of carbon dioxide (CO2) in our atmosphere could result in catastrophic sea level rise, there is no evidence to support this fear. Tax monies spent trying to solve this non-existent problem are a complete waste.

…

climate-debate

Sea level rise: what’s the worst case?

by Judith Curry, November 30, 2018 in WUWT

Draft of article to be submitted for journal publication.

Well, I hope you are not overdosing on the issue of sea level rise.  But this paper is somewhat different, a philosophy of science paper.  Sort of how we think about thinking.

I would appreciate any comments, as well as suggestions as to which journals I might submit to.  I have two in mind, but am open to suggestions (and I may need backups).

Thanks in advance for your comments.

Sea level rise: What’s the worst case?

Abstract. The objective of this paper is to provide a broader framing for how we bound possible scenarios for 21st century sea level rise, in particular how we assess and reason about worst-case scenarios. This paper integrates climate science with broader perspectives from the fields of philosophy of science and risk management. Modal logic is used as a basis for describing construction of the scenario range, including modal inductivism and falsification. The logic of partial positions and strategies for speculating on black swan events associated with sea level rise are described. The rapidly advancing front of background knowledge is described in terms of how we extend partial positions and approach falsifying extreme scenarios of 21st century atmospheric CO2 concentrations, warming and sea level rise. The application of partial positions and worst-case scenarios in decision making strategies is described for examples having different sensitivities to Type I versus Type II errors.

…

climate-debate

Special Report on Sea Level Rise

by Judith Curry, November 27, 2018 in ClimateEtc.

I have now completed my assessment of sea level rise and climate change.

The complete report can be downloaded here [Special Report- Sea Level Rise  ].

My preliminary compilation of information was provided in the 7 part Climate Etc. series Sea level rise acceleration (or not).

This report reflects 18 months of work on this topic. Why have I devoted so much time to the sea level rise issue? First, I regard sea level rise to be the most consequential potential impact of predicted global warming. Second, there is a great deal of public confusion about the issue, including decision makers. Third, a number of CFAN’s clients have queried me about a range of specific concerns that they have regarding sea level rise (and I have been doing consulting on this topic).

Why do I think an independent assessment of the sea level rise issue by yours truly is needed, given the plethora of international and national assessment reports? My clients are concerned about the alarmist predictions they have encountered. I have seen various ‘experts’ make public statements projecting 21stcentury sea level to be as high as 9 m [30 feet]. My clients are looking for someone that they trust to provide an objective assessment that focuses on their issues of concern.

…

climate-debate

Climate Alarmism Dies In 2018 As Modern Ice Melt, Sea Level Rise Has No Net Impact On World’s Coasts

by Kenneth Richard, November 15, 2018 in NoTricksZone

The year 2018 could mark the beginning of the end of climate change alarmist reporting.  Projections of catastrophic melting of the ice sheets and sea level rise swallowing up the Earth’s coasts are increasingly undermined by observation.

…

Despite the hackneyed practice of reporting “staggering” ice sheet melt for both Greenland and Antarctica in recent decades, the two polar ice sheets combined to add just 1.5 centimeters to sea level rise between 1958 and 2014 (graphfrom Frederikse et al., 2018) as global sea levels only rose by “1.5 ± 0.2 mm yr−1 over 1958–2014 (1σ)” or “1.3 ± 0.1 mm yr−1 for the sum of contributors”.

That’s about 7.8 centimeters (3.1 inches) of global sea level change in 56 years.

…

climate-debate

Hothouse claims from ‘Trajectories of the Earth System in the Anthropocene’ are in a virtual world, not the real world

by Albert Parker, November 2, 2018 in WUWT

A recent paper Trajectories of the Earth System in the Anthropocene (Ref. [1] below) claims that even if the CO2 emission reductions called for in the Paris Agreement are met, our Earth may still enter what they call “Hothouse Earth” conditions, a long-term stabilization at temperature 4-5 °C-higher than pre-industrial temperatures, and sea-level 10-60 m-higher than today. They conclude calling for an accelerated transition towards a CO2 emission-free-world-economy. There is, however, very little evidence that the apocalyptic prediction is scientific grounded. Where really measured, the temperatures haven’t increased dramatically, and similarly, the sea-levels haven’t risen dramatically. More importantly, any acceleration of the temperature warming, or any acceleration of the rate of rise of the sea-level, are hard to detect.

Figure 1 –sample long-term-trend thermometer results (Alice Spring, NT, Australia). The temperatures were recorded in the Post Office / City and Airport locations. Data downloaded from www.bom.gov.au/climate/data/.

…

 

climate-debate

Climate Study: 90 Percent Of Atolls And Islands Either Stable Or Growing

by J. Delingpole, October 30, 2018 in ClimateChangeDispatch

Another global warming scare story bites the dust: fragile islands and atolls in the Pacific are not sinking beneath the waves because of global warming. In fact, they are doing just fine.

The bad news (only bad for alarmists, of course) comes in a study by Virginie Duvat of the University of La Rochelle-CNRS, France, titled ‘A global assessment of atoll island planform changes over the past decades’.

It surveyed 30 Pacific and Indian Ocean atolls, including 709 islands, and found that 90 percent have either remained stable or have grown in the last few decades.

…

climate-debate

CNN: “Climate change endangers dozens of World Heritage sites”… Unmitigated horst schist

by David Middleton, October 19, 2018 in WUWT

Holocene Sea Level

I didn’t take the time to look up the dates of these World Heritage sites… But I’m going to guess they’re OLD.  Many of them probably date back to the Early to Mid-Holocene.  [My bad… That was a bad guess.  The Late Holocene (Meghalayan Age) begins in 4200 BP (2250 BC)]  Here’s a Holocene sea level reconstruction for the Arabian Gulf, with a recent reconstruction of global sea level since 1800 (Jevrejeva et al., 2014) and the satellite sea level trend from CU…

…

climate-debate

1989 UN report: ‘By 2000, coastal cities will be underwater’

by David Hilton, September 30, 2018 in EndtimesHerald

By the year 2000, according to the 1989 story:

Coastal flooding and crop failures would create an exodus of ″eco- refugees,′ ′ threatening political chaos, said Noel Brown, director of the New York office of the U.N. Environment Program, or UNEP.

He said governments have a 10-year window of opportunity to solve the greenhouse effect before it goes beyond human control.

Well we’re here in 2018, Noel, it’s nearly October, and I’m sitting here in South-East Queensland at midday in a jacket because it’s cold.

…

climate-debate

Sea Level Speculation Irresponsibly Threatens Property Owners

by Jim Steele, September 26, 2018 in WUWT

…

The suggested steady 3.3 mm/year rise since 1992 conflicted with CO2-driven model predictions of acceleration. So, based on the difficulties of calibrating altimetry with tide gauge data, various researchers claimed satellite drift and biases had over-estimated early estimates of sea level rise from 1994-2002. Various adjustments were then evoked, and varying rates of sea level rise published. New global sea level estimates rose at an accelerating rate from 1.8 in 1993 to 3.9 mm/yr today, others at 2.2 mm/yr in 1993 to 3.3 mm/yr in 2014, yet others found satellite adjustments lowered the average rate of sea level rise to 2.6 mm/yr over that same period. Elsewhere Harvard geophysicists were analyzing the effects of mass change on the earth’s rotation and wobble and were disturbed by the misfit between geophysical observations and sea level estimates. They argued that only if 20thcentury sea level rise was limited to 1.2 mm/yr could there be a good fit with geophysical expectations.

climate-debate

Retracing Antarctica’s glacial past

by Louisiana State University, September 25, 2018 in ScienceDaily

More than 26,000 years ago, sea level was much lower than it is today partly because the ice sheets that jut out from the continent of Antarctica were enormous and covered by grounded ice — ice that was fully attached to the seafloor. As the planet warmed, the ice sheets melted and contracted, and sea level began to rise. Researchers have discovered new information that illuminates how and when this global phenomenon occurred.

…

More recently in 2002, in the northern part of Antarctica called the Antarctic Peninsula, the Larsen Ice Shelf collapsed. The collapse of this ice shelf quickly led to inland glaciers buttressed by the Larsen Ice Shelf to break up and melt. Scientists have thought that a similar process could have occurred when the Ross Ice Shelf collapsed thousands of years ago in the West Antarctic Ice Sheet.

However, Bart and colleagues from the University of South Florida, Auburn University and the Polish Academy of Sciences found that there was a centuries-long delay from when the Ross Ice Shelf collapsed and the grounded ice began to contract. In the Ross Sea, the delay was between 200 to 1,400 years later. This new information adds a layer of complexity for sea level rise computer simulations and predictions.

…