New Science: 89% Of The Globe’s Islands – And 100% Of Large Islands – Have Stable Or Growing Coasts

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Rapid sea level rise was supposed

to shrink Earth’s coasts. It hasn’t.

Image Source: Mörner, 2018

Over the past decades, atoll islands exhibited no widespread sign of physical destabilization in the face of sea-level rise. 88.6% of islands were either stable or increased in area, while only 11.4% contracted. It is noteworthy that no island larger than 10 ha decreased in size. These results show that atoll and island areal stability is a global trend, whatever the rate of sea-level rise.”- Duvat, 2019

Image Sources: Donchyts et al., 2016 and BBC (press release)

I. Despite sea level rise, “the coasts are growing all over the world”

Sea levels aren’t rising fast enough to deleteriously affect coastal areas on a net global scale.

Satellite observations indicate there has been 13,565 km2 of net growth in land area across the globe’s coasts between 1985-2015.

In other words, the Earth’s coasts gained more land area than were lost to rising sea levels.

“Earth’s surface gained 115,000 km2 of water and 173,000 km2 of land over the past 30 years, including 20,135 km2 of water and 33,700 km2 of land in coastal areas.” (Donchyts et al., 2016)

As a visual example, Ahmed et al. (2018) find that Bangladesh’s coastal land area grew by 7.9 kmper year during 1985-2015.

“This paper draws upon the application of GIS and remote sensing techniques to investigate the dynamic nature and management aspects of land in the coastal areas of Bangladesh. … This research reveals that the rate of accretion [coastal land growth] in the study area is slightly higher than the rate of erosion. Overall land dynamics indicate a net gain of 237 km2 (7.9 km2annual average) of land in the area for the whole period from 1985 to 2015.”  (Ahmed et al., 2018)

Image Source: Ahmed et al., 2018

II. Even with ~4 mm yr−1 local sea level rise, Pacific islands grew in size during 1971-2014

Between 1958-2014, the globe’s sea levels rose at a rate of about 1.4 mm yr−1 , or 14 centimeters (5.5 inches) per century (Frederikse et al., 2018).

Ice melt from Greenland and Antarctica contributed a grand total of 1.5 cm of the 7.9 cm (3.1 inches) of sea level rise during those 56 years.

“The global-mean sea level reconstruction shows a trend of 1.5 ± 0.2 mm yr−1 over 1958–2014 (1σ), compared to 1.3 ± 0.1 mm yr−1 for the sum of contributors.” (Frederikse et al., 2018)

However, there are regions of the world where sea levels are rising at rates two or three times the global average.  Tuvalu, representing over 100 islands located in the central west Pacific, has  undergone “twice the global average” rate of sea level rise (~3.90 ± 0.4 mm yr−1) since the 1970s.

It would be expected that such high rates of local sea level change would result in shrinking island coasts and overall land area during this period.

But the opposite has occurred.  There has been a net increase in the coastal land area of Tuvalu between 1971-2014 in 8 of 9 atolls.

“We specifically examine spatial differences in island behaviour, of all 101 islands in Tuvalu, over the past four decades (1971–2014), a period in which local sea level has risen at twice the global average. Surprisingly, we show that all islands have changed and that the dominant mode of change has been island expansion, which has increased the land area of the nation.”
“Using remotely sensed data, change is analysed over the past four decades, a period when local sea level has risen at twice the global average (~3.90 ± 0.4 mm yr−1). Results highlight a net increase in land area in Tuvalu of 73.5 ha (2.9%), despite sea-level rise, and land area increase in eight of nine atolls.” (Kench et al., 2018)

III. The stability or coastal net growth of islands in recent decades to century “is a global trend”

Coastal stability and expansion for atoll and island land area is not just a regional trend, but a global one.

A comprehensive (709 islands) review of coastal changes that have been observed in the last decades to century (Duvat, 2019) reveals that no atoll island destabilization has occurred due to the effects of rising sea levels.

In fact, 88.6% of the globe’s islands have coasts that are either stable or expanding in size.

Further, not a single island larger than 10 hectares [1 ha = 10,000 square m, or 2.5 acres] has decreased in size in recent decades.

None of these observed trends affirm the popularized claim that modern sea level rise is currently threatening the globe’s coasts.


Duvat, 2019

A global assessment of atoll island

planform changes over the past decades

Image Source: Duvat, 2019
This review first confirms that over the past decades to century, atoll islands exhibited no widespread sign of physical destabilization by sea level rise. The global sample considered in this paper, which includes 30 atolls and 709 islands, reveals that atolls did not lose land area, and that 73.1% of islands were stable in land area, including most settled islands, while 15.5% of islands increased and 11.4% decreased in size. Atoll and island areal stability can therefore be considered as a global trend.”
“Importantly, islands located in ocean regions affected by rapid sea-level rise showed neither contraction nor marked shoreline retreat, which indicates that they may not be affected yet by the presumably negative, that is, erosive, impact of sea-level rise.”
“It is noteworthy that no island larger than 10 ha decreased in size, making this value a relevant threshold to define atoll island areal stability.”
[A]mong the 27 islands having a land area lying between 100 and 200 ha (9 in French Polynesia, 6 in the Marshall Islands, 6 in Kiribati, 5 in Tuvalu and 1 in the Federated States of Micronesia), only 3 increased in area, while 24 were stable.”
“The great majority of Pacific islands showed positional stability, as illustrated by the Tuamotu atolls, where 85–100% of islands were stable, depending on atolls (Duvat & Pillet, 2017; Duvat, Salvat, et al., 2017).”
“Importantly, the reanalysis of available data on atoll island planform change indicates that over the past decades to century, no island larger than 10 ha and only 4 out of the 334 islands larger than 5 ha (i.e., 1.2%) underwent a reduction in size.”

IV. Sea level rise is not the coastal threat that natural geological processes are

Rapid sea level rise rates due to global warming are not the threat to coastal communities and wildlife that they have often been claimed to be.  What is?  Natural geological/crustal changes, or vertical land movement.

Tied to the Earth’s gravitational attraction and shifting plates, geologic subsidence (land sinking) or uplift (land rising) processes are far more of a determinant of coastal structure and positioning than the rather small (by comparison) seawater volume changes in the world’s ocean basins.  This is why sea level rise (or fall) rates are local, not global, as they vary quite dramatically across the world.

Along the coast of Juneau, Alaska, for example, the land surface has been rapidly rising due to gravitational uplift for many decades.  Consequently, relative sea levels are plummeting in this region at a rate of over -13 mm yr−1 (minus-5 inches per decade) according to NOAA.

The opposite is occurring along the U.S. Gulf coast (Grand Isle, Louisiana), where the land area is sinking and thus sea levels are rising at a rate of over +9 mm yr−1.

Scientists have concluded that “sea level rise is not the primary factor controlling the shoreline changes” in regions where sea levels are rapidly rising (Testut et al., 2016).   Even localized rates of sea level rise as high as 5 mm yr−1 are not rapid enough to overcome the much more pronounced geologic changes (accretion and uplift).

We show that Grande Glorieuse Island has increased in area by 7.5 ha between 1989 and 2003, predominantly as a result of shoreline accretion [growth]: accretion occurred over 47% of shoreline length, whereas 26% was stable and 28% was eroded. Topographic transects and field observations show that the accretion is due to sediment transfer from the reef outer slopes to the reef flat and then to the beach. This accretion occurred in a context of sea level rise: sea level has risen by about 6 cm in the last twenty years and the island height is probably stable or very slowly subsiding. This island expansion during a period of rising sea level demonstrates that sea level rise is not the primary factor controlling the shoreline changes. This paper highlights the key role of non-climate factors in changes in island area, especially sediment availability and transport.”  (Testut et al., 2016)

V. Vertical motions of the Earth’s crust exert “dominant control” over relative sea level

Along the eastern coast of the U.S., Piecuch and colleagues (2018) find that the “dominant control” over the disparate rates of sea level rise during the modern era has been exerted by “vertical motions of the Earth’s crust”, not climate.

“Here we analyse instrumental data and proxy reconstructions using probabilistic methods to show that vertical motions of Earth’s crust exerted the dominant control on regional spatial differences in relative sea-level trends along the US East Coast during 1900–2017, explaining most of the large-scale spatial variance. … Rates of coastal subsidence caused by ongoing relaxation of the peripheral forebulge associated with the last deglaciation are strongest near North Carolina, Maryland and Virginia [locations where the sea level rise rates are highest]. Our results indicate that the majority of large-scale spatial variation in long-term rates of relative sea-level rise on the US East Coast is due to geological processes that will persist at similar rates for centuries. … We note that negative VLM [vertical land motion] reflects subsidence and hence contributes to sea-level rise. Correspondingly, the most negative VLM [vertical land motion] rate (−2.5 ± 0.6 mm yr−1) is likely (P = 0.75) to occur in the states that host the maximum sea-level rise, North Carolina or Virginia, whereas the most positive rate of VLM (0.7 ± 0.8 mm yr−1) is very likely (P = 0.90) to occur in Maine.” (Piecuch et al., 2018)

Pfeffer and colleagues (2017) assessed 849 coastal sites and determined that geophysical processes, or vertical land motion (VLM) trends (ranging from −13 to +16 mm yr−1 ), “have been recognized as a dominant component of the total relative sea-level variations observed at coasts” at locations throughout the globe.

VLMs contribute actively to the sea-level changes felt by coastal populations, as they can amplify, diminish or counteract the effects of climate-induced signals (e.g. Pfeffer & Allemand 2016). In many cases, for example, Torres Islands (Ballu et al. 2011), western Tropical Pacific (Becker et al. 2012), southern Europe (Woppelmann & Marcos ¨ 2012) or Indian Ocean (Palanisamy et al. 2014), VLMs [vertical land motions] have been recognized as a dominant component of the total relative sea-level variations observed at coasts. … VLMs are estimated at 258 GPS stations and 591 tide gauges, for a total of 849 coastal sites. Trend values range from −13 to +16 mm yr−1 (Fig. 3a). A strong spatial variability in VLM is observed at all scales, including locally, which is evidenced for example by the dense instrumental network in Japan. High rates of crustal uplift are observed at high latitudes, while subsidence of coastal areas is more often observed at medium latitudes (e.g. the East American coast).” (Pfeffer et al., 2017)

VI. Meter-scale sea level rise is “related to geologic events only”, not climate change

In a 2018 paper published in the journal Geoscience Frontiers, geophysicist and tectonics expert Dr. Aftab Khan asserts that “both regional and local sea-level rise and fall in meter-scale is related to the geologic events only and not related to global warming and/or polar ice melt.”

Very high rates of land subsidence and uplift persist today.  Vertical land motions as profound as ±10 to 30 mm yr−1 have been observed by geologists – easily overwhelming even the highest measured relative sea level changes.

The conclusion that rapid and high-amplitude (i.e., meters-per-century) sea level changes occur primarily as a consequence of natural geologic processes effectively leaves no room for global warming and/or polar ice melt to significantly contribute to the alarming meters-per-century sea level rise projected to engulf the Earth’s coasts by the end of the century.

Modeled predictions of multiple meters of sea level rise by 2100 (for example, 2.6 meters of global sea level rise by 2100 according to authors like Dr. Michael Mann and Dr. Richard Alley in Garner et al. 2017) are dismissed as “highly erroneous” by Dr. Khan.

Suggestions of a controlling anthropogenic influence on coastal and shoreline changes — the scariest aspect of climate modeling predictions — may therefore be significantly undermined by real-world scientific observations.


Khan, 2018

Why would sea-level rise for global

warming and polar ice-melt?

“Geophysical shape of the earth is the fundamental component of the global sea level distribution. Global warming and ice-melt, although a reality, would not contribute to sea-level riseGravitational attraction of the earth plays a dominant role against sea level rise.”
“Geological processes are responsible of two types of major movements of the crustal block viz., uplift and subsidence. Hence, the relation of sea level and crustal motion is attributed to sea level drops when there is an uplift while it rises when there is subsidence.”
“Snay et al. (2016) have found large residual vertical velocities [land uplift], some with values exceeding 30 mm/yr, in southeastern Alaska. The uplift occurring here is due to present-day melting of glaciers and ice fields formed during the Little Ice Age glacial advance that occurred between 1550 A.D. and 1850 A.D.”
“Johansson et al. (2002) conducted research on a project BIFROST (Baseline Inferences for Fennoscandian Rebound Observations, Sea-level, and Tectonics) that combines networks of continuously operating GPS receivers in Sweden and Finland to measure ongoing crustal deformation due to glacial isostatic adjustment (GIA). They have found the maximum observed uplift rate 10 mm/yr for Fennoscandian region analyzing data between August 1993 and May 2000. Sella et al. (2007) and Lidberg et al. (2010) suggested that postglacial rebound continues today albeit very slowly wherein the land beneath the former ice sheets around Hudson Bay and central Scandinavia, is still rising by over a centimeter a year, while those regions which had bulged upwards around the ice sheet are subsiding such as the Baltic states and much of the eastern seaboard of North America.”
“Transgression commences when continental block undergoes subsidence with respect to continental shelf and abyssal plain, while regression occurs when this process is reverse i.e., when continental block is uplifted with respect to continental shelf and abyssal plain. Prograding delta system in low lying areas and other geologic events may cause local/relative sea-level fall as new sedimentary deposition advances as accretion pushing sea further down the coast irrespective of global warming and polar ice-melt.”
“Hence, both regional and local sea-level rise and fall in meter-scale is related to the geologic events only and not related to global warming and/or polar ice melt.”
Prediction of 4–6.6 ft sea level rise in the next 91 years between 2009 and 2100 is highly erroneous.”
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33 responses to “New Science: 8933 Of The Globe’s Islands – And 10033 Of Large Islands – Have Stable Or Growing Coasts”

  1. willy

    Can someone explain me how Earth’s surface can grow?

    1. SebastianH

      A river transports material towards the coasts. Some of the material doesn’t vanish into the oceans and thus grows the coastline (e.g. the surface grows). Another mechanism is caused by continental plates moving against each other. Cliffs can also erode into the ocean and form a larger in size coastline that before the erosion.

      1. Kurt in Switzerland

        Seb,

        Nice try.

        So about those growing islands.

      2. Robert Folkerts

        Seb, I remember some time ago you scoffed when I made the comment that all the sediment being deposited into the oceans displaces water and necessarily causes sea level to raise.

        1. SebastianH

          Please quantify then. Kenneth seems under the impression that uplift is what’s going on, so more land is “sticking” out of the oceans thus probably causing sea level to decline if nothing else was going on. Do you agree?

          @Kurt: as with trash collecting on beaches, other material will acrete there as well when conditions are right.

          1. Robert Folkerts

            I think it would be difficult to quantify sea level rise due to sedimentation. There are so many factors which affect the erosion rate. Plus the effects of uplift and subsidence. I think it is sufficient to understand logically it is a contributor to sea level variation. That it isn’t the sole domain of land based ice melt which affects the sea level!!! Or thermal expansion/contraction.

    2. willy

      Thanks for the answers but I still feel confused.
      I know the diameter of Earth the last decades grew a few decimeters due to sealevel rise but can that explain an 288.000 km2 total (land+water) surface gain?
      Or do they mean land surface in 3D and not the projected surface on a 2D map.

      1. SebastianH

        The gain in water surface is a loss of land surface and the other way around. You should not add up those two figures.

        1. willy

          If I can’t just add up the figures, I still can subtract them:
          173.000 – 115.000= still 58.000 km2 netto (land)surface growth.

    3. Anthony Lucas

      Uplift and subsidence are fundamental processes in Expansion Tectonics which predicts (requires) a continuous annual increase in the Earth’s radius. The process described in article above are entirely consistent with expansion tectonics and requires no ad hoc bolt on explanation.
      There are plenty of books available on the subject (via Amazon) if you have an interest and are geologically inclined.

      1. willy

        Thanks for answering.
        …..which predicts (requires) a continuous annual increase in the Earth’s radius.
        I was not aware of a continuous increase in Earth’s radius.
        Do the Jason satellites take this into account?
        Wiki says: “Although it was suggested historically, since the recognition of plate tectonics in the 1970s, scientific consensus has rejected any significant expansion or contraction of Earth.”
        My simple question is sincere although probably I’m missing something obvious. I sincerly hope to get an answer.

        1. raygun

          The Earth’s surface collects millions of tons of space debris annually, anywhere from small grains to meteorite fragments. Certainly less that 0.00001% of the entire mass. Rotation has been slowing over millions of years and the orbit has changed, also. But considering the existence of life as we know it, it never happened.

        2. Anthony Lucas

          Willy, 18 January, 12.39.
          I would not pay any attention to wiki in relation to Expansion Tectonics. There has been a small turf war at Wiki on this subject. Everything written there is from the plate tectonic perspective. Anything from an Expansion Tectonic perspective is quickly overwritten.
          If you are interested you need to to do the searching independently for yourself.
          Regarding satellite measurement: papers have been published supporting both sides of the argument. It is possible to select papers supporting either side of the arguments depending on your preferred bias.
          It is a subject of ongoing interest, although it should be noted that NASA is strongly in the consensus camp of Plate Tectonics.

  2. SebastianH

    Between 1958-2014, the globe’s sea levels rose at a rate of about 1.4 mm yr−1 , or 14 centimeters (5.5 inches) per century (Frederikse et al., 2018).

    Why always point out the average sea level rise over a long timeperiod of accelerating rise? What is the current rate? What will be the rate in another 50 years if the acceleration continues as in those past 56 years?

    Ice melt from Greenland and Antarctica contributed a grand total of 1.5 cm of the 7.9 cm (3.1 inches) of sea level rise during those 56 years.

    Actually, Antarctica alone contributed 1.4 cm (+- 0.2 cm) from 1979 on until 2017:
    https://www.pnas.org/content/early/2019/01/08/1812883116

    And the mass loss there is accelerating as well:
    40 Gt/y from 1979 to 1990, 50 Gt/y from 1989-2000, 166 Gt/y from 1999 to 2009 and 252 Gt/y from 2009 to 2017. All parts are losing ice mass.

    As with all data series that show acceleration, looking at the past average change and imagining that the future won’t be too bad (e.g. similar to the past) is a bit strange.

    Vertical land movements as profound as ±10 to 30 mm yr−1 have been observed by geologists – easily overwhelming even the highest measured relative sea level changes.

    What if the land movement has the opposite sign or no movement at all? Land is not rising at this rate everywhere since there are no melting glaciers everywhere (the reason for an uplift that high), right?

    One can use the website Aqua Monitor (http://aqua-monitor.appspot.com/) to easily see where lang area is decreasing and increasing. There is a certain pattern to those changes. And don’t worry, it’s the official data that was gathered, not some “fake climate activist stuff” 😉

    Modeled predictions of multiple meters of sea level rise by 2100 (for example, 2.6 meters of global sea level rise by 2100 according to authors like Dr. Michael Mann and Dr. Richard Alley in Garner et al. 2017) are dismissed as “highly erroneous” by Dr. Khan.

    Glad that Dr. Kahn can do that. Since simply extrapolating the current acceleration to 2100 results in how many meters of sea level rise? That would indeed be unpleasent. Let’s hope thermal expansion and ice melt stabilize between now and then despite it doesn’t look like that will be the case from where what we know today.

    “Prediction of 4–6.6 ft sea level rise in the next 91 years between 2009 and 2100 is highly erroneous.”

    That’s not the official prediction of the IPCC though, right? That’s for pretty special scenarios. With no further acceleration we are looking at a rise of more like 1 ft in 91 years.

    This sounds smallish, but the thing is that the sea level that we speak of is kind of an average. We have tides, we have storm floods. Extreme events will be more devastating with a higher average. That’s a problem.

    Trying to ignore thermal expansion and ice melt because “geological events” exist is a special kind of crazy. The same kind that makes you guys call more CO2 a good thing, I guess 😉

  3. Stephen Richards

    Bang; there goes the UN climate damage slush fund. They will have to pay the US and China instead

  4. Steve

    I have noticed that it is taking me a lot longer to drive across Australia nowadays.

    1. Yonason

      A millimeter here, a centimeter there. It adds up. //;o)

      Mark Twain would have almost certainly had something to say about it, too.
      http://www.gutenberg.org/files/8474/8474-h/8474-h.htm

      In the space of one hundred and seventy-six years the Lower Mississippi has shortened itself two hundred and forty-two miles. That is an average of a trifle over one mile and a third per year. Therefore, any calm person, who is not blind or idiotic, can see that in the Old Oolitic Silurian Period,’ just a million years ago next November, the Lower Mississippi River was upwards of one million three hundred thousand miles long, and stuck out over the Gulf of Mexico like a fishing-rod. And by the same token any person can see that seven hundred and forty-two years from now the Lower Mississippi will be only a mile and three-quarters long, and Cairo and New Orleans will have joined their streets together, and be plodding comfortably along under a single mayor and a mutual board of aldermen. There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact

  5. scott allen

    If you still believe the people at NASA, they claim the earth is shrinking in diameter (but not by much).

    https://www.nasa.gov/topics/earth/features/earth20110816.html

    And would the sea level rise due to an expanded land mass of 13,565 km2
    by simple displacement?

  6. raygun

    ANOTHER wasteful federal study. Meaningless. As Item V (5, Five) concludes the major and minor tectonic plates, even over geologic time, can’t be adequately predicted to account for any accurate sea level/land mass movement. What happens, happens. And there’s nothing any human society can do about it. Get use to it. Don’t fight it.

  7. Rosco

    In all of this speculation about sea level rise/fall or accelerating/decelerating trends or land subsidence/uplift there is only one certainty and that is 420 ppm atmospheric CO2 and 1.86 ppm atmospheric methane have absolutely nothing to do with any of the waste of money initiated by Jim Hansen spreading his special brand of manure in the US Senate 30 odd years ago.

    1. Stephen Way

      Hear Hear !

  8. What is PAL-reviewed papers? – Newsfeed – Hasslefree allsorts

    […] Read rest at No Tricks Zone […]

  9. Yonason

    RE – “What is PAL-reviewed papers? – Newsfeed – Hasslefree allsorts 20. January 2019 at 7:26 PM”

    INSECTS DYING
    https://www.newscats.org/?p=18259

    Oh Nooooooos!!!!

    What will the UN zombies do for food?
    https://www.bbc.com/news/world-22508439

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