Review of rising sea levels around the world

Not very alarming.

The bottom line

Where the ground is stable, typical change appears to be a rise of 1- to 2-mm/y. Rates above 3 mm/y seem to have a substantial component of natural and/or anthropogenic subsidence. Rates above 10 mm/y appear to be a primarily a consequence of human activity, which implies they should be manageable to some degree.

Summary

Most of the world’s largest coastal cities border the Pacific Ocean. In recent decades, apparent sea-level has dropped at Nagoya, Lima and perhaps Jakarta. Sea level has likely risen 1- to 2-mm/y at Qingdao, Shantou, Guangzhou-Shenzhen-HK, Seoul, Tokyo and Los Angeles. It has apparently risen 5- to 6-mm/y at the delta cities of Osaka, Tianjin and Shanghai-Hangzhou. The effect of urban activity is clear in apparent rises of 15 mm/y at Manila and 18 mm/y at Bangkok.
For the Atlantic Basin, sea level has likely risen about 2-mm/y at Buenos Aires, London and Rio de Janeiro. Perhaps any change at São Paulo or Lagos has been similar. The apparent rise at Istanbul might be more than 2 mm/y, and apparent rise of 3 mm/y at New York might be due in part to subsidence.
For the Indian Ocean, sea level has likely risen 0.5- to 2-mm/y at Chennai, Mumbai and Karachi. The delta city of Kolkata has seen an apparent rise of 7 mm/y.
Delta cities and others on unconsolidated sediments have higher apparent rises. However, gauges in the Netherlands show that sea-level change in highly developed regions on unconsolidated sediments can be kept close to change seen generally around the world.

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23 Responses to Review of rising sea levels around the world

  1. Nicholas (Unlicensed Joker) Gray

    Obviously, the only way to deal with these alarming rises is to suspend democracy, make Tim Flannery the national dictator, and execute critics. Who else has got a little list of annoying people whom nobody would really miss?

  2. Leo G

    No meltwater pulse due to the reported unprecedented increase in atmospheric carbon dioxide? How could that be?

  3. Cradock's Choice

    But the narrative! The narrative!

    If the pure-twaddle’n’BS narrative is not supported, the great green blob vampire-squidding the taxpayer’s wallet might get less money!

  4. John64

    That means I will still be able to enjoy the fisherman’s basket with an accompanying cold beverage at the Metung Hotel for foreseeable future.

    Good news indeed.

  5. herodotus

    So there should be no more mentions of “dangerously rising sea levels” on our ABC.
    That’ll be the day.

  6. Norman Church

    So Robyn William’s scary predictions are only a tad out of whack?

  7. OldOzzie

    From The Australian Bob Carter 12th December 2014

    Tide turns on sea-level alarmists

    AUSTRALIA is lucky to possess the high-quality, 128-year-long tide gauge record from Fort Denison (Sydney Harbour), which since 1886 indicates a long-term rate of sea-level rise of 0.65mm a year, or 6.5cm a century.

    Lucky, because 60-year-long oceanographic atmospheric oscillations mean a true long-term measurement of sea-level rise can be made only when such a record is available.

    Similarly low rates of local sea-level rise have been measured at other tide gauges along the east coast. National Tidal Centre records reveal variations between about 5cm and 16cm/century in rates of relative rise. The differ­ences between individual tide gauges mostly represent slightly differing rates of subsidence of the land at each site, and differing time periods.

    For example, measurements at Sydney between 2005 and 2014 show the tide gauge site is sinking at a rate of 0.49mm/yr, leaving just 0.16mm/yr of the overall relative rise as representing global sea-level change. Indeed, the rate of rise at Fort Denison, and globally, has been decreasing for the past 50 years.

    Despite this high-quality and unalarming data, it is surprising that some east coast councils have implemented coastal planning regulations based on the computer projections of the UN’s Intergovernmental Panel on Climate Change. For instance, a recent consultancy report for the Shoalhaven and Eurobodalla shire councils, informed by IPCC computer model projections, advised those councils to plan using a rate of rise of 3.3mm/yr, four times the rate at Fort Denison.

    The numbers were in part based on experimental estimates of sea-level change provided by satellite altimetry measurements. NASA’s Jet Propulsion Laboratory, which launches the satellite platforms, says these estimates contain errors larger than the sea-level signal claimed and proposes spending more than $US100 million on launching a new GRASP satellite to rectify the matter.

    Mindful of these facts, on October 28, Shoalhaven Shire Council rejected advice to use the IPCC’s most extreme emissions Scenario 8.5, applying the still highly precautionary Scenario 6.0, and using their nearest long tide gauge record (Fort Denison) to set future planning policy. The council specifically ruled out the future use of satellite or model-generated sea-level estimates until their accuracy is guaranteed.

    In mid-2010, the Eurobodalla council, south of Shoalhaven, introduced a unique interim sea level rise policy that shackled more than a quarter of all properties in the shire to restrictive development controls. Predictably, there was an immediate shire-wide decline in property values.

    Figures from RP Data property information specialists show that between 2011 and 2014, Eurobodalla property values suffered a 5.3 per cent loss in value compared with increases of 4.9 per cent and 7.3 per cent for neighbouring coastal shires that didn’t have equivalent restrictive sea-level policies. In the worst cases, individual properties have lost up to 52 per cent of their market value.

    In three years, individual Eurobodalla properties lost about $40,000 in value. With 22,000 properties in the shire, this represents a capital loss of $880m at a rate of $293m a year. This steady loss of rateable value means householders will face higher rate increases.

    If similar policies were implemented along the entire east coast there would be annual property capital losses of billions of dollars.

    So it is not surprising that NSW and Queensland governments are reconsidering their coastal management policies.

    Queensland Deputy Premier Jeff Seeney recently notified Moreton Bay Regional Council of his intention to direct it to amend its draft planning scheme “to remove any assumption about a theoretical projected sea level rise due to climate change from all and any provisions of the scheme”. Seeney said his intention was to use a statewide coastal mapping scheme “that will remove the ‘one size fits all’ approach that incorporates a mandatory 0.8m addition to historical data”.

    At last, a responsible government has recognised that global average sea-level change is no more relevant to coastal management than average global temperatures are to the design of residential heating and cooling systems — local weather and local sea-level change is what matters.

    Satellite measurements and computer model projections are not accurate enough for shire planning. As the NSW Chief Scientist has said, coastal policy needs to be informed by the best available factual measurements.

    And as Seeney said: “All mandatory elements of the (planning) scheme must reflect only proven historical data when dealing with coastal hazards such as storm tide inundation and erosion control areas.” Similar policies need to be espoused by all state governments and councils.

    Sea-level alarmism has passed high tide and is at last declining. With luck, empirical sanity will soon prevail over modelling.

  8. Bruce J

    Just a couple of thoughts from a non-scientific mug:
    1. The larger rises in delta locations would more likely indicate the land is subsiding than sea rising as the depth of silt to bedrock would be decreasing as the silt compresses with time.
    2. All the measurements relate sea level to land level at specific points, so how are we sure it is the sea rising and not the land sinking?
    3. The earth as a sphere in space is cooling (and has been for millions of years since it formed), and the magma, etc would be decreasing in volume as it cools, thus reducing the radius of the sphere so the same volume of water and rock on the surface would be covering a diminishing area. If this is the case, the depth of water would increase and the sea level rise.

    Anybody else got any thoughts on these lines – to demolish or support them?

  9. Bruce

    “Delta cities and others on unconsolidated sediments have higher apparent rises. ”

    I suppose that nobody would have thought this odd.

    “UNCONSOLIDATED” sediments? I wonder what THAT could mean. Any word on whether this “rise” in the seas / delta around Kolkotta, etc. is more noticeable during the wet season?

    The orbiting moon drags entire oceans around the planet, causing TWICE DAILY rises and falls of anything up to 16.3 METRES (Bay of Fundy, Canada).

    Entire continents are shoved up and down and sideways ALL THE TIME, by enormous geological forces.

    Pretty much EVERY coral atoll on the planet is the result of an undersea volcano being shoved up from thousands of feet below sea level and coral colonizing the upper slopes and finally, as the rim of the crater / caldera erodes, the top of the rim. As long as the coral polyps can keep up with the rate of erosion of the volcanic substrate, the atoll will exist and grow.

  10. Phill

    Bruce, you mention that entire continents are shoved up and down and sideways all the time. Literally very true. As I understand it, earth tides pull the ground under our feet up and down by about 500 mm every 12 hours or so. I don’t personally notice that movement, but I have no reason to doubt it is happening.

    Anyway, I for one don’t care whether the sea level rises or not, what with all this other larger tidal bouncing going on. I am a bit surprised that the left hasn’t followed its normal course of action, by finding some vaguely human cause for earth tides, asserting it will get worse, demanding we “think of the children” and slapping a tax on it.

    Besides, a recent US President, in 2008, said that “this is the moment when the rise of the oceans began to slow and the earth began to heal”. Surely he wasn’t fibbing?

  11. Leo G

    The earth as a sphere in space is cooling (and has been for millions of years since it formed), and the magma, etc would be decreasing in volume as it cools

    I believe the thickness of Earth’s mantle is presently contracting at a rate of about 1 metre per million years after a peak at 3.3 billion years ago when it was about 20 kilometre thicker than present.
    There are also the effects of water migrating from the mantle and water lost to space.

  12. Dr Faustus

    The Earth’s crust is continually in motion.

    – It’s pulled up and down by the gravity of the Moon and Sun – so continually different deflections of about 100-300+mm (sort of) daily;
    – The crust ‘ripples’ as the continental plates move over the mantle;
    – The crust (including the ocean floor) changes shape and position where the continental plates collide, or separate, or grate past each other;
    – Faults slip and lock, moving huge blocks of surface crust around – suddenly as in earthquakes, or just slow motion as in the sinking east coast of the UK;
    – In places the crust is still bobbing up from being weighted down in the mantle by several km of ice during the last glacial period;
    – And on top of that, the whole thing wobbles like a jelly.

    Beware anybody who tells you that measured movement in a tide gauge means the sea level is evidence of manmade warming – or is inevitably going to continue.

  13. Suburban Boy

    Norman Church: No, this proves that Williams was dead right with his 100-metre prediction. It’s just going to take 50,000 years or so to get there.

  14. Norman Church

    Suburban Boy – oh, I see now. Could have sworn that he mentioned a slighter tighter timeframe. But that is probably just my mistake. Muchas dopey meo.

  15. spangled drongo

    Thanks, OldOzzie, for those data. I have been trying to impress on local councils in the Moreton Bay area that my own observations of king tides during fine weather [around normal barometric pressure-not tide surge during storms and cyclones] are that these king tides are lower today than they were after WW2, 70 years ago. The same benchmarks I used then are still in existence and I check them every year.

    As with Sydney’s Fort Denison there is nothing happening and the most valuable waterfront property is being devalued by the bed wetters.

    Local sea levels are all you can go on and on the east coast there is nothing to worry about.

  16. Nerblnob

    Very few people anywhere have acted like they really believed this catastrophic sea rise shit. Never mind what they say.

  17. Tel

    A number of times I’ve offered to swap my house and land in Western Sydney for something the same size on a Sydney beachfront, but the response has been somewhat unenthusiastic.

  18. cohenite

    If you want to have fun with sea level and how the alarmist’s predictions are grotesquely wrong go to the Monash University’s Sahul time interactive graph which shows sea levels in the past.

  19. faceache

    An old friend, and now an acquaintance (his choice), who can’t forgive me winning 5Gs on the Donalds win, tells me that Port Phillip Bay is safe from sea level rise because its not part of the ocean. Thats what we are up against.

  20. iain russell

    Tel, indeed. Similarly, I have asked for years when the housing bubble will burst so I can pick up a new or old three beddy, two bath in Manly with ocean views for say AUD150K. Stony silence.

  21. Beertruk

    At the current rate of the rising sea level, I worked it out a while ago that I would have beachfront property here in Toowoomba in about 500,000 years.

  22. cohenite

    According to the Monash interactive graph 2.4 million years ago sea level was 15 meters higher than today. The coal burning must have been going gangbusters then.

  23. Up The Workers!

    To Tel and iain russell, you could both be in luck.

    I just happen to know of three people who have the great misfortune to currently live in multi-million dollar Taj Mahals on water-frontage sites, each of which are in grave danger of biblical-style apocalyptic flooding.

    One is the renowned expert in dinosaur coprolites, Professor Tim Flannery (NOBODY speaks crap more authoritatively than HE does!) whose house on the Hawkesbury River in New South Wales has no road access and is only accessible by boat.

    One is a certain “Professor, Doctor” Juliar Gillard, in the suburb of Brighton, South Australia (Nobody speaks crap more prolifically than she does); and the third is Fat Al Bore (Nobody has ever made more cash from speaking crap, than he has), who owns multiple sea-front mansions in the United States of Trumpland, which worry him terribly and reputedly plays hell with his second “chakra”.

    Given that each of the above professional bloviators have gotten filthy rich off the back of the carpet-bagging ‘rising sea-levels / gerbil worming / carbon dioxide is a dangerous killer poison gas’ scam, either they have each bought or built their mansions on the shores of the worlds’ only seas or oceans or rivers which are somehow “immune” to a rise in sea-levels, or alternatively, EVEN THEY reckon that they are a bunch of slimy hucksters, scammers and outrageous frauds, and wouldn’t believe in a single lying word they utter.

    As the former possibility is grossly scientifically improbable, and as they know themselves far better than I do, I am prepared to take their word for it!

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