Sea level rise and "sinking Vanuatu"

UPDATE 23 January 2010: Adelaide University Professor Barry Brook was kind enough to provide the authoritative resources for monitoring of sea level rise in the area of Vanuatu. I have escalated Barry’s comment here to the top of the post so that new readers of this post can easily go directly to the SeaFRAME programme, which is the superior resource for further information:

You need to correct for crustal movements and a range of other biasing factors in order to accurately assess localised sea level rise. This is standard practice. The most comprehensive monitoring of the SLR in the Pacific Basin and Australia is the SeaFRAME (Sea Level Fine Resolution Acoustic Measuring Equipment) programme, which includes coverage of Vanuatu:

http://www.bom.gov.au/pacificsealevel/project_info.shtml

http://www.bom.gov.au/pacificsealevel/images/Pkg33.gif (map)

Latest Vanuatu report here:

http://www.bom.gov.au/ntc/IDO60034/IDO60034.2007.pdf

With all appropriate corrections applied, the rate for Vanuatu is 2.5 mm/yr.

Dear reader, I recommend that you proceed directly to the SeaFRAME links above provided by Dr. Brook — don’t bother reading the rest of this post. Lastly, for a superior resource on energy policy that can have a real impact on global climate change I recommend that you investigate Dr. Brook’s website BraveNewClimate.com.
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ORIGINAL POST CONTINUES: What is the real story on sea level rise? Is catastrophe already producing fleeing populations? I’ve started looking into the measurements that have been published. E.g., the above local trends map is from the University of Colorado at Boulder sea level change project.

Local trends are calculated with a least-squares fit of 10-day, 1-degree resolution grids of sea level. A trend, bias, annual, and semi-annual terms are fit simultaneously.

Please note that these trends have been determined for only a fourteen-year period, and reflect the impact of decadal scale climate variability on the regional distribution of sea level rise.

Their site is a model of open science and open data and processing. Here is some of the Pacific Ocean raw data (with inverse barometric correction applied).

The next chart shows the global average satellite altimetry data from 1993 through 2009. The trend over that period continues to be around 3.2mm per year. So far there is no evidence of accelerating sea level rise. The global mean change in sea level over the 1993-2009 period is about 50mm or 2 inches.

The data is very noisy. Below the trend chart is a global map showing the variance of the local trend data plotted above. On quick inspection it appears that the “hot spots” showing high positive increases have variance almost as large as the signal.

Local changes can be very different from the global mean, including falling sea level trends. To investigate local trends there is an interactive display tool. Here I found my knowledge of the data and processing procedures lacking. E.g., I don’t understand why the local trends map I have displayed looks very different from the first map shown above.

So, more homework to be done. What is the truth and significance of this meme

The people of Vanuatu are already feeling the pointy end of climate change. Rising sea levels, bleached coral reefs and turbulent weather is affecting VanuatuÂ’s tourism and its main export, coconuts. In late 2005, an entire coastal village in northern Vanuatu was relocated to higher ground. One hundred residents of Tegua Island became the first climate change refugees.

We just spent two months cruising New Caledonia which is just south of Vanuatu. We saw no evidence of material sea level rise anywhere in New Caledonia. Similarly, we met with a number of other yachts who have been cruising Vanuatu – nobody reported anything unusual there.

UPDATE: In the comments, John Nicholls has contributed some first-hand reports on the Maskelynes group in Vanuatu. I emailed John regarding sea level rise datum “When you report one meter/year rise are you measuring vertical -> water level height; or horizontal -> lost beach?” John replied “horizontal”. So we have anecdotal evidence of increasing horizontal beach coverage. The UC Boulder satellite data above shows a maximum of 15mm/year rise in that general part of the South Pacific. At a beach slope of 1:67 that translates to one meter per year of “horizontal breach drowning”. I would guess the beach slopes are more like 1:20 so there is a factor of 3 mismatch between the satellite observations and John’s anecdotal report.

9 thoughts on “Sea level rise and "sinking Vanuatu"

  1. One island that is loosing a meter a year to the sea is Ulivero island, it is part of the Maskelynes group of islands in Vanuatu.
    I photographed it in 2008, see: http://picasaweb.google.com/VanuatuTravel/MaskelyneIslandsVanuatu#

    If you look carefuly at the village’s main beach you will see felled coconut trees in the water, where it used to be land. Homes that were 10 meters from the shore are now literaly at the waters edge.

    Tropical regards,
    John Nicholls
    Port Vila Vanuatu

  2. John,

    Thanks heaps for the info on Ulivero island. Could you please post a link to the one of the pics that you describe?

    We are on a very-limited monthly data budget in NZ – which limits our ability to browse through your great pics looking for the main beach with felled trees.

    Also, have you seen any internet sources that track the measurements of sea level rise at Ulivero island.

  3. Hi Steve, see: http://picasaweb.google.com/VanuatuTravel/MaskelyneIslandsVanuatu#5393743234179847922

    You can see the coconut tree stumps (dark)on the right, the photograph was taken at low tide, at high tide the water is now reaching the “land” trees (coconut trees being “beach” trees). You can imagine 10 meters of real beach with coconut trees scatered everywhere, these are all gone exept for the ones (stumps) which were at the rear of the beach.

  4. Reference rising sea levels, is it assumed, in the case of Vanatua,
    that the ground level is a constant?
    I suppose that, as it once rose up to form an island, it may now be subject to movement which is depressing its true level creating the impression of rising sea level.

  5. Date 12/26/09

    Combating Global Sea Rise

    Not sure if anyone has considered this before, but there are a number of areas below sea level that isn’t too far from the ocean where a simple canal could be established to allow water to flow from the ocean to fill some deep areas on dry land and help offset global sea rise. Areas such as the Qattara Depression could be filled by ocean water. A simple cannel that would hardly support a boat could enlarge itself through erosion to allow for a larger flow of water to fill this natural depression.

    Africa is in the process of breaking apart with low-lying areas that will be filled by the sea at some point in the future, and those who depend on water today are struggling because of these geographical changes and the lack of water. By establishing a canal to fill these low-lying areas with sea water, this will result in more rainfall in the region and help to establish better farmland.

    Another example of a low-lying area is Israel, where the Dead Sea is shrinking. A canal from the sea with a dam could regulate the height of the Dead Sea to a desirable level.

    Also, water from Lake Erie could be redirected to the southwest to refill aquifers.

    http://geology.com/below-sea-level/

    Mathew Sullivan
    Boynton Beach, Florida

  6. I read on the internet that Vanuatu is one the many pacific islands countries that will disappear from the map ?? Is it true ???

  7. Johnny,

    No, it is not true. Vanuatu islands vary but are mountainous, highest elevation Tabwemasana 1,877 m.

    The Tuvalu outcry at Copenhagen was mostly clever positioning by the PR consultant they hired. Tuvalu is nothing like Vanuatu — when Tuvalu is underwater then worry about Vanuatu.

    There is indeed a coastal threat to Vanuatu, but it will happen slowly, even if the local sea level change is up in that 9mm/year range (vs. global average around 3.4mm/year).

    But, a two-foot increase in average sea level will be a very big deal for every coastal area. Even here in 1st world New Zealand.

  8. You need to correct for crustal movements and a range of other biasing factors in order to accurately assess localised sea level rise. This is standard practice. The most comprehensive monitoring of the SLR in the Pacific Basin and Australia is the SeaFRAME (Sea Level Fine Resolution Acoustic Measuring Equipment) programme, which includes coverage of Vanuatu:

    http://www.bom.gov.au/pacificsealevel/project_info.shtml
    http://www.bom.gov.au/pacificsealevel/images/Pkg33.gif (map)

    Latest Vanuatu report here:
    http://www.bom.gov.au/ntc/IDO60034/IDO60034.2007.pdf

    With all appropriate corrections applied, the rate for Vanuatu is 2.5 mm/yr.

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