The Sky is Falling Friday Part 2: Why Japan’s coastal zones might be disappearing due to climate change

Public Release: 13-Jul-2017

Projections of future beach loss in Japan due to sea-level rise and uncertainties in projected beach loss

World Scientific

As G20 Summit 2017 drew to a close, the issue of climate change divided the world. As it happened, 19 of the 20 leaders were able to agree on all points made in the joint declaration (known as the communique)–with the exception of Donald Trump, who could not agree on climate change; thus resulting in ‘G19’ (i.e. G20 sans the United States) releasing a joint statement on climate change. Leaving politics aside, for the people around the world who inhabit as much as 71% of the world’s coastlines and are surrounded by oceans, this is not just a statement on a piece of paper, but a commitment of world leaders to take the wellbeing of our further generations to heart, to tackle the burning of fossil fuels and global warming collectively.

Climate change can cause a range of effects on coastal environments. Some of the effects are related to erosional processes such as a decrease in sediment supply, changes in the intensity and frequency of extreme events (storms and cyclones, among others), and changes in sea levels and in the wave climate. The estimation of changes due to sea level rise (SLR) and climate change is a major issue with respect to future coastal management decisions.

No one is more concerned than the Japanese, who are surrounded by seas; about 73% of Japan is forested, mountainous, and unsuitable for agricultural, industrial, or residential use, as a result, the habitable zones are mainly located in or near coastal areas, so much so that, there are growing concerns in Japan of the impact of climate change on their coastal surroundings, prompting the Japanese government to set up an Intergovernmental Panel on Climate Change (IPCC) to undertake a study on climate change, to provide future projections of coastal erosion based on representative concentration pathway (RCP) scenarios. So far, the study indicates that rising sea levels (SLR) and increasing maximum wave heights due to climate change would lead to shoreline retreat.

Japan’s coasts have already undergone significant erosion due to rapid national development after World War II; future beach erosions would significantly affect areas behind the coasts where both population and property are densely concentrated. The first projection of future beach erosion all along Japanese coasts was published in 1994 by Mimura et al. (1994), who calculated that beach erosion caused by SLR would occur in values of 0.30, 0.65, and 1.00m based on the projections of the IPCC First Assessment Report (IPCC, 1990). Twenty years later, Udo and Takeda (2014) projected the rate of beach loss at SLR values of 0.1 to 1.0m using the same method as Mimura et al. (1994), further refined with a different beach data set obtained from 1/25,000 scale maps issued by the Geospatial Information Authority of Japan (GSI) (Kishida and Shimizu, 2000). In their investigation, Udo and Takeda (ibid) determined beach-loss rates of 49% for an SLR of 0.3m and 93% for an SLR of 1.0m. Yoshida et al. (2013), had projected future beach erosion using the Bruun rule (Braun, 1962) due to SLR for SRES A1B to have the greatest effect on beach erosion.

In the study by Keiko Udo and Yuriko Takeda, published in Coastal Engineering Journal on 29th May 2017, the authors projected beach losses in the 77 coastal zones throughout Japan caused by future SLR (2081 to 2100) relative to a reference period (1986 to 2005) using 21 CMIP5 models, and constructed a beach-loss curve for SLR averaged along the entire coastline of Japan. Uncertainties due to different SLR projections and sediment sizes were also taken into consideration. Finally, temporal changes in beach loss rates from 2007 to 2100 were given for the projections of GMSLR for each RCP scenario, and the histograms of mean beach width in the 77 coastal zones were projected for the future.

The beach-loss rate in the future (2081 to 2100) was projected by the Bruun rule to be 62% for the ensemble mean RCP2.6 scenario, 71% for RCP4.5, 73% for RCP6.0, and 83% for RCP8.5; the rates projected by the 21 models for RCP4.5 ranged widely from 61% (MRI-CGCM3) to 87% (MIROC-ESM). Although the effect of the spatial distribution of SLR in each CMIP5 model on beach loss rate in Japan is insignificant, the effects of differences in the SLR values among the RCP scenarios and CMIP5 models are significant. The maximum uncertainty caused by the sediment size (0.2-0.6mm) against the same SLR was 38%.

Projections of the beach-loss rate from 2007 to 2100 for GMSLR of the different RCP scenarios revealed that the rates were between 18% and 79% and differed by 60% in the near future and between 28% and 96% differed by 70% in the future. Large uncertainties were caused by the GMSLR scenario and sediment size; however, the minimum projected rate of beach loss was 18% in the near future, and this rate of loss is expected to have significant implications for coastal management. For the upper bound scenario in the near future, the projected beach width in more than half of the 77 coastal zones is 0-10 m, which would cause serious damage to coastal areas in consideration of coastal protection, environmental concerns, and beach utilization. Hence, in conclusion, the authors stated that beach loss due to SLR is an urgent issue that must be addressed through the development of better coastal management strategies to combat beach loss.

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For more information, contact Dr Yan-Hong Ng at yhng@wspc.com

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.

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43 thoughts on “The Sky is Falling Friday Part 2: Why Japan’s coastal zones might be disappearing due to climate change

    • Really?
      Models all the way down.
      If [this] then [that].
      I think coastal erosion at twelve kilometers/month will eliminate North America within the life of some children born today.
      Ok – Mods – I help you. /SARC!!!
      Jolly double-plus /SARC!!! in truth . . .

      Auto

  1. Beach Loss? If China can build islands in the China Sea, and the Netherlands can build dykes to keep out the sea all those decades and more than 100 years ago, what is all the hand wringing about.? There are enough engineers in the world to tell you how to fix such minor problems as beach and coastal erosion.

      • Tell that to the millions that live in the valleys of the mountains in Japan. Those valleys are not only home to the people but also the soil is very productive for their agriculture.

      • Perhaps Japan could flatten some of those mountains through materials mining and use the tailings to rebuild the beaches

      • Holland if flat , Japan in mountainous. Totally different.

        I don’t get your meaning. Since Japan is mountainous, they have material the sand reefs in the China Sea did not have. Those new islands had to be built by bringing in material by ship. Japan only needs trucks.
        Maybe you were using sarcasm?

  2. Japan’s population will go down 20 million by 2050. link The loss of land will be offset by the loss of population. There is no problem.

    • It has been my observation that nature, in the short term or long, has a way of balancing everything out rather nicely.

    • It’s more like the loss of reason and logic will lower the population. Too stupid to live if they let their politicians pretend that there will be major land loss based on fantasy-island computer simulations.

  3. Japan and the rest of the world have been dealing with SLR, erosion, and beach losses for 22,000+ years. Suddenly immediate drastic policies are necessary to try and slow it.

  4. … about 73% of Japan is forested, mountainous, and unsuitable for agricultural, industrial, or residential use …

    That’s just crap. You can build a self-sufficient residential community almost anywhere. Consider, for example, The Wall.

    “The Wall is home to City Hall, businesses, schools, a health centre, and 440 residences! … [Not to mention], Fire truck, Sports Centre, Swimming Pool, and a Hotel.

    Lots of people, like Japan’s huge population of seniors, don’t have to go out to work. They could easily be housed in a beautiful scenic location that is otherwise unsuited to an industrial economy.

  5. In addition to Fukushima, how many other nuclear facilities in Japan are affected? How many more around the globe are also affected?

    • Sites like Fukupshima should not be a problem since they rely on a sea defence wall. You could easily make it 1m higher.

      If fact, if they had done so they would not have had a problem.

      I would have thought that with what, 160k DEATHS they would be a lot more concerned about vulnerability to tsunamis which hit with about 30min warning than 1m rise with over 100 years warning.

      Just more “climate change MAY cause UP TO …..” by 2100.

      YAWN.

      • I seem to remember when that big Tsunami hit, they blamed Climate Change and George Bush specifically.
        So, fear not – they covered that base too.

        I’m sure Al Gore would have put a stop to it.

      • Al Gore?
        Al Gore II?
        Al Gore III?

        There is/was a shedload of them.
        Maybe Al Gore IV [I can’t be bothered to check, frankly.]

        Any particular one you have in mind for staying the tsunami?

        Auto

      • They can have all the scary campfire stories they want. In the real world geostationary tide gauges show global sea level rise at less then 2 mm per year, and ZERO acceleration.

  6. Japan’s coasts have already undergone significant erosion due to rapid national development after World War II;

    Ah, so it’s a development issue then, not “climate change”. Thought so. If you are going to develop coastline, don’t go crying to the rest of the world when it goes wrong.

  7. Just thinking aloud
    Maybe they should check the tides and see how they changed over time.
    I think in Japan the erosion could simply be due to the sun and the movement of moon and earth’s inner core.

  8. So long as the rate of sea level rise continues to be less than the rate at which sea defences need to be renovated anyway… the cost of AGW is approximately zero.

    Now the cost of fighting AGW… that’s a different story.

  9. But let’s build more billion-dollar high-rise condominiums 2 feet above the high tide line everywhere–because ocean VIEW, y’know . . . ;-)

  10. So now a slow change in weather constitutes a greater threat than the fact that Japan sits on a series of massive tectonic fault lines, is extremely prone to earthquakes and is one of the most active volcanic island chains in the world. This is the real danger to life and limb in Japan. Anyone who thinks non- tectonic coastline change in Japan is a bigger threat needs to lay off whatever they’re imbibing and stick to drinking carrot juice or something similarly vile but relatively harmless.

    • Yeah, I’m thinking that volcanoes and earthquakes are a somewhat greater hazard than globull warming. And I think Japan would sink beneath the waves like Atlantis before there’s much actual sea level rise.

  11. Climate changes for the time being as it always has, that’s the nature of climate, to change…
    Twelve thousand years ago the world experienced a very fast heating after hundred thousand years of ice age. The global temperatures rose very fast without the help of humanity, and the CO2-level came after, according to ice core analyseses, some 800 years later. On such a background it’s hard to claim that humanity is the cause of the present changes.
    Since the WW2 we have had three phases of climate and temperatures, the first from 1940 to 1978 when global temperatures went down. The second phase was 1980-1998 when temeratures rose a bit and the last period from 1998 has been a “hiatus”, a pause with no increase of temperatures…
    It’s to me quite impossible to see the connection between CO2-emissions and rise of temperatures…

  12. They are modeling the change in shorelines based on models of the change in temperature. The latter have already failed validation. The former are most likely built on a house of cards. Don’t breath too hard or the whole mirage of catastrophe may fall away in a second.

  13. …19 of the 20 leaders were able to agree on all points made in the joint declaration (known as the communique)…

    Only because they “agreed” this does not mean that it is going to happen.
    The one that got away without agreeing will, in the end, fleer at those idiots who parrot the narratives of profiteers.

  14. Check PSMSL.org for actual sea level and GPS land level data. Japan tide gauges show some that are stable, others rising ,and others falling. Land GPS shows similar variations. Seems that sea level effects are local and that there is no such thing as an all-Japan sea level issue.

  15. Odd thing about the oceans and beaches.
    Whatever the level, oceans just make more beaches.

    (Sorry, Wa;run, for copying your style.8-)

  16. If the Japanese have not moved to higher ground since the Great Tohoku earthquake of 11-Mar-11 and tsunami, they are damned fools. The gradual rise of the oceans is nothing compared to tsunamis.

    • From the Japan Meteorological Agency

      “In contrast to the globally averaged rate noted in the IPCC report, sea levels in Japanese coastal areas showed no significant rise from 1906 to 2010; the rate of rise around the country was 1.1 [0.6 to 1.6] mm/year from 1971 to 2010, and 2.8 [1.3 to 4.3] from 1993 to 2010. These figures are comparable to those observed for the global average in recent years”.

      Perhaps they don’t need to rush

      And much of the sea level variation around Japan will be due to local variations; bits of Japan rising or falling [which happens a lot] rather than the sea level changing

  17. I believe it was Willie Soon who said something like pity those who are unable to step back a bit due to a 4″ rise in sea level.

  18. Japan — Surrounded by ocean on all sides lengthy landmasses. Most of the changes along the coastal zones are mainly associated with Tsunamies, earthquakes, construction activities, etc.

    Dr. S. Jeevananda Reddy

  19. I’ve decided that I’m going to start a website that displays all the climate predictions/ prognostications that have or haven’t come true. There will be no bias, simply a running score of predictions that can be shown, through science, to have come or not.

    Come December 31, 2100 we’ll look at the score and decide on who won. Of course I’ll be dead by then, unless I become the oldest living person at 131 years old. I’m sure I’ll be able to pass the coal fired torch to someone else to keep score.

  20. Even the most cursory look at the (tectonic) plate boundaries close to Japan should inform researchers of the uncertainties in partitioning relative and absolute sea-level change.

    I suppose the models could produce any result you want depending on a few adjustments in the assumptions.

  21. ” …but a commitment of world leaders to take the wellbeing of our further generations to heart, to tackle the burning of fossil fuels and global warming collectively.”

    “I am from the government, and I am here to help you.”

  22. i always laugh with beach erosion: here in Belgium we got actually a beach “buildup”: the silting of the area we call “zwin” is proof of that: it made Bruges obselete and moved the activity to antwerp…

    Actually now we got beach erosion since the mid 50’s…

    Not because of climate change, but because of the fact that now all of our coast is a sea wall with a whole strip of high rise buildings instead of sand dunes….. that makes that the dunes by storm tide aren’t broken down to broaden and naturally heighten the beach anymore.

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