UPDATE: Sunday 5/6/12 7PM PST – The FAIL occurred, with the predication hype not even close. Read here: Tuvalu flooding FAIL – no supermoon tide of any significance
Guest post by Andi Cockroft
The MSM down under are running with a story about the next close encounter with the moon due in the next day or so, a “super-moon”, and the likely impacts on the low-lying Tuvalu Island Nation.
With a population of just over 10,000, Tuvalu – formerly known as the Ellice Islands – is one of the smallest nations in the world, just ahead of the Vatican!
From Wikipedia:
At its highest, Tuvalu is only 4.6 metres (15 ft) above sea level, and Tuvaluan leaders have been concerned about the effects of rising sea levels for some years. Whether there are measurable changes in the sea level relative to the islands of Tuvalu is a contentious issue. There were problems associated with the pre-1993 sea level records from Funafuti which resulted in improvements in the recording technology to provide more reliable data for analysis. The degree of uncertainty as to estimates of sea level change relative to the islands of Tuvalu is reflected in the conclusions made in 2002 from the available data. The 2011 report of the Pacific Climate Change Science Program published by the Australian Government] concludes: “The sea-level rise near Tuvalu measured by satellite altimeters since 1993 is about 5 mm per year.”
A nearby neighbor are our friends over at Kiribati, who must be completely wetting themselves (but not by high tides) at the thought of all that wonderful UN monies due to head their way. A moon at perigee should be like Manna from Heaven.
But what if nothing significant happens? What then?
At perigee, the moon approaches its closet to earth, and this particular approach is being referred to as a “Super Moon”.
Video here:
According to website “Stuff”, the interactive arm of Fairfax media:-
A “super-moon” will be a novelty for New Zealanders on Sunday, but for the 12,000 people of Tuvalu it is a foreboding practice for a future where rising seas make their homeland uninhabitable.
On Monday and Tuesday super-moon king tides will leave much of the capital atoll of Funafuti virtually below sea-level.
On Sunday night the Moon will be 14 per cent bigger and 30 per cent brighter than any other full moon this year, the US space agency NASA says.
Known as a “perigee moon”, it occurs when the moon reaches its closest point to Earth.
The full moon will occur at 3.35pm on Sunday, New Zealand time, but will not be visible here until moonrise over New Zealand at 5.23pm.
With a clear sky, it guarantees Sunday night will be a bright one.
NASA says the super moon has a reputation for trouble, causing high tides, making dogs howl and keeping people awake.
The space agency says the best time to look at it is when the moon is near the horizon.
But what is the reality of a Moon at Perigee?
According to those folks over at NOAA, very little – see here.
An extract:
The moon is the primary source of the gravitational forces which cause the tides. The proximity of the moon in relation to the earth does have an effect on the range of the tides at any given time. In each of its 28-day elliptical orbits, the moon reaches a “perigee,” its closest point of approach to the earth. During these periods, there will be a slight increase in the average range of tides. The increases in the range of the tides is seen by a slightly higher than average high tide, as well as a slightly lower than average low tide. Additionally, twice each month, around the times of the new moon and full moon, when the earth, sun, and moon are nearly in line, there is an increase in the average range of the tides. These are called “spring tides.” Three or four times a year, the occurrence of a new or full moon will coincide with the “perigee” of the moon, which Mr. Wood has termed the “perigean spring tides”.
The difference between the “perigean spring tides” and the normal tidal ranges for all areas of the coast is small. In most cases the difference is only a couple of inches. The largest difference occurs in certain areas of the Alaska coast where the range of the tide was increased by approximately 6 inches. But considering that these areas have an average tidal range of more than 30 feet, the increase is but a small percentage of the whole (less than a 2% increase).
So, will Tuvalu vanish beneath the waves? Well unless it’s less than 2 inches above seal-level, then probably not – so no worries there then.
I really do feel a rather smug FAIL coming on – then again it wouldn’t be the first time I’ve been wrong – hence stopping gambling on the gee-gee’s.
SØREN, very enlightening video. That sure answered some of my misconceptions about tides and earthquakes to boot. So it is land-tide in realty, not the water and i could never quite understand that with water about 1/8th the density (but had never stopped to dig it up either). Thanks.
The moon can appear to be larger in the sky during either perigee or apogee, in the video it’s suggested that the ‘moon illusion’ only occurs during perigee, this is untrue, the ‘moon illusion’ is purely in the ability of our brains perception and interpretation of it’s surroundings.
Although the moons orbit can be calculated to be closer to the earth or further away, we can not perceive these mathematical differences of the size of the moon either at perigee or apogee by simply looking. If you’re a newbie to observational science you will find this a baffling concept.
See: “The theory of shape constancy”.
I found a pretty good explanation for this phenomenon with an interactive graphic of size constancy here; http://science.howstuffworks.com/question491.htm
As for the high tides, it’s not unusual to have flooding especially coinciding with a storm or wet weather during a high tide, but the high tides alone causing a widespread disaster sounds like a FAIL to me too (but predictions aren’t my thing, I wasn’t blessed with a crystal ball like some).
Here is the sea level data for Tuvalu from the Permanent Service for Mean Sea level …
http://www.psmsl.org/data/obtaining/rlr.monthly.plots/1452_high.png
pretty scary stuff.
“A “super-moon” will be a novelty for New Zealanders on Sunday, but for the 12,000 people of Tuvalu it is a foreboding practice for a future where rising seas make their homeland uninhabitable.”
So, it will be sort of a ‘dry run’ then.
Cue the wailing and teeth-gnashing. Man the lifeboats! Lookout, Australia, here come the “climate refugees”.
cmarrou says:
May 4, 2012 at 8:19 am
I for one blame the United Nations – for admitting a “nation” whose highest point is only 15 feet above sea level. Simply a recipe for disaster from Day One. Even godforsaken Houston, Texas gets up to 125 feet, and we’re still awaiting a ruling whether it’s fit for human habitation…
__________________________
Not according to me, it isn’t.
However, all of my relatives and friends that live in Houston disagree and can’t figure out why I live where I do.
http://www.mojvideo.com/video-bob-dylan-i-feel-a-change-comin-on/3551124e5886d97189fc
Bob is feeling it too. Maybe a Tuvaluan band could use it as an anthem during the event.
“I feel a fail comin’ on” sung to this tune is OK too.
The Nasa film was not very good. The moon at perigee will only appear 14% bigger if you are at the equator and even then it will NOT appear 14% bigger “than any other moon this year”. Lunar perigee occurs every 27.5 days. You would think NASA might know this.
You do not need “rulers in the sky” to measure the width of the moons visible limb as seen from Earth. Do this easy bit of backyard astronomy. It is fun with friends and family.
Assuming you can find an unobstructed view of the eastern horizon and the sky is clear, wait until the moon has appeared on the horizon. Everybody will agree that it looks very big. Now hold an ordinary clear plastic rule at arms length in front of you and measure the moon in millimetres
(sunglasses help here). Make a note of the number. Now wait a few hours until the moon is high in the sky. You and your friends will agree that it looks a lot smaller now. Measure it as before. To your suprise it will be the same number you had earlier.
That is the Moon Illusion. A trick of perception.
Peter Crawford,
Yes, it’s an illusion. The reason is because near the hoizon there are reference points such as trees, hills, buildings, and the horizon itself. Looking straight up, there is nothing to compare the moon’s size to.
Alan Watt says:
May 4, 2012 at 5:36 am
So now I’m not being fair, as I should be. And how am I being unfair?
Because I said “tide predictions are here”, and you claim I should have noted that the graph contains tide predictions …
Man, there’s no pleasing some people. Yes, Alan, JUST AS I SAID those are predictions. You can tell, see, because I left a clever clue for the initiated when I called them “tide predictions”. And yes, as you point out the predictions are never exactly what happens … which may be why they are called “predictions” rather than say ” future facts”.
Setting that aside, you are correct that tides can be lower or higher than predicted from a host of effects, including:
Am I being fair now?
Sheesh … no pleasing some people …
w.
DISCLAIMER: Any predictions in the above comment are predictions. Past performance is no guarantee of future success. Predictions may not be 100% accurate. Not valid where taxed or licensed. This comment complies with all provisions of the Fair Tidal Reporting Act. No electrons were harmed in the preparation of these predictions.
The answer seems obvious–did I miss somebody saying it?
Send the people that kept Guam from tipping over down to Tuvalo to build what ever it takes to jack it up out of harms way.
Latitude says:
May 4, 2012 at 8:19 am
Not true. The Tuvalu gauge is part of the SEAFRAME project, which maintains very accurate (albeit short) records including GPS to measure land subsidence. The most recent data is here, and says:
It’s an interesting report, well worth reading.
However, the record is only 19 years long, so the same paper says the 95% confidence interval is about ± 2.8 mm/year … so we’re 95% sure it’s rising, but how much it is rising is much less clear …
w.
Check out the PBS Pacific Heartbeat episode on Takuu Atoll which is north-east of PNG and only about a meter above high tide. Multiple issues are affecting its fate
http://pacificheartbeat.org/?page_id=11
(Time to possibly display my ignorance but …) If the moon is full then the Earth is between the Sun and the Moon. Wouldn’t a New Moon over Tuvalu produce a higher tide? Or would this be slightly higher because the Moon itself is closer?
Typos. I’ve to learn to check my typing before I hit “Post Comment”.
“… Moon, wouldn’t …”
Bill Tuttle says:
May 4, 2012 at 1:57 am
On Sunday night the Moon will be 14 per cent bigger and 30 per cent brighter than any other full moon this year, the US space agency NASA says.
Does NASA say where that additional 14% mass will come from and where it will be going on Monday?
++++++++++++++++++++++++++++++++++++++++++++
They are going to begin shooting a remake of “The Honeymooners”. Ralph is finally going to send Alice to the Moon. Rosie O’Donnel is playing Alice.
(I did it again! I shouldn’t have said that!)
@P. Solar says:
May 4, 2012 at 4:33 am
“capital atoll of Funafuti virtually below sea-level.”
Virtually, like the climate is “virtually” warming. We should be virtually ready to give them some virtual money to help them with this virtual problem.
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LOL! My virtual donation is on the way to help all the virtual climate refugees who didn’t turn up their virtual trouser cuffs.
I had to explain this about the moon to my eleven year old nephew (coincidentally) this evening!
His response was hilarious, he said, “If I stand here, you will see me close up and I’ll be this size and if I’m far away from you I’ll look smaller” (he then ran to the other side of the room) “so if I’m the moon the closer I get to you the bigger I’ll look” (he then walked back). I said, “the moon never gets far enough away from us that we can see it getting bigger or smaller, When the moon looks bigger or smaller It’s only our perspective using the naked eye that it appears bigger or smaller”, It blew his mind.
I have to give the little guy credit tho, Jupiter is very bright in the sky and this past fue months he has enjoyed pointing it out to everyone, I think he gets a kick out of it every time I confirm that his observation is correct in person to his friends including his granny and aunt. lol
Well… science isn’t all about political crap, It’s fun and interesting, but engineering is better building block for young minds in my opinion, the time I built an r2d2, it was more inspirational to them (and got more Wow’s) than if I just showed them a picture or if they found a book to read on building r2d2s.
Just a thought, I hope I’m not to far OT.
Small, Far Away.
Jake says:
May 4, 2012 at 2:52 am
[…] Many if not all volcanic islands in the southern ‘Ring-of’fire’ sink as the magma chambers move underneath them. The Hawaiian islands are slowly moving as the newest islands grow and the smallest sinks. In time another Island will pop up as the vents move.
It’s lithospheric plate movement above asthenopheric ‘hot spots’ that allow island arc formation and they’re moving relatively quickly at about five inches a year:
http://www.platetectonics.com/book/page_17.asp
A couple of points:
Tides are complicated, but a lot has been understood about them since classical times. The first rough tide tables were produced a millenium ago in China. I believe that tide tables were fairly important in the days of sailing ships. Captains desired to ride ebb tide out of harbors. And in some ports one had to make sure there was enough water under the keel to get in and out of harbour. Folks like Newton and Laplace devoted considerable time to analyzing tides. Very accurate tide predictions have been available for quite some time. At least a century. I’m guessing more like two or three centuries. See http://en.wikipedia.org/wiki/Tide
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ALAN says: May 4, 2012 at 12:59 am –“Wasn’t there an article saying that Tuvalu was actually growing due to deposition rather than disappearing? Or is my poor old memory failing me again?”
I think that your memory is fine. The problem is probably that removing the affects of variable winds, local marine topography, etc from tidal gauge measurements is very difficult so sea level measurements have substantial uncertainty. You probably need measurements over many years to get accurate numbers. Snapshots of a few months or years can be misleading. Or they might be dead on.
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Bloke down the pub says: May 4, 2012 at 1:51 am –“If in the past, sea level had been higher then the islands would now be that much higher too.”
One would think so, but the coral/coral debris the islands are built from is almost certainly a bit soluble whenever volcanic activity or other phenomena lead to acidic rain. I’m guessing that the erosion rate of coral islands is high compared to, for example, the Ordovician metasediments underlying Manhattan. I’ve done some some looking and so far haven’t hit upon any serious research on coral island erosion … yet.
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bushbunny says: May 4, 2012 at 12:40 am — “Tuvula has removed sand and gravel from its foreshores and should be erecting sea walls.”
Maybe. Sea levels clearly vary a lot with glaciation, and glacial melt. It appears that there is a mechanism — possibly coral growth plus storm debris accreation that keeps coral islands (barely) above sea levels. In that case, building sea walls may be the last thing residents of low coral islands want to do. It’s not clear to me what the optimum strategy for these island dwellers might be although I suspect that whining about sea level rise (which may not even be very important at many islands) is not it. See http://joannenova.com.au/2010/08/south-pacific-sea-levels-no-rise-since-1993/
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Willis Eschenbach says: May 4, 2012 at 11:34 am — “The Tuvalu gauge is part of the SEAFRAME project, which maintains very accurate (albeit short) records including GPS to measure land subsidence.”
Yes. In the long run, the CGPS data will probably be very important to the discussion. Unfortunately, GPSs aren’t great at measuring altitude (It’s a geometry thing) and a very long observation period is surely required to get millimeter accuracy. Although SEAFRAME has 19 years of data, I believe that the GPSs weren’t installed until a number of years into the project. Detail looking into GPS altitude measurement of tidal gauges is on my todo list. But it’s not going to happen this morning.
And yes, sea levels probably are rising a bit. Even Axel Morner — probably the most vocal critic of sea level measurement science and, in his opinion, science fantasy — acknowledges a few inches a century.
Pamela Gray says:
May 4, 2012 at 6:43 am
Each individual adult is responsible for their own survival. Yet it never fails to amaze me. People who live on atolls, sand spits, river banks, tree crowded wilderness areas, and sandy hill sides yell the loudest when disaster strikes. Those that build their houses upon stable bedrock and soil on cleared land take disasters in stride.
I don’t care one wit why seas rise. Move if you find your perch precarious.
<b!= =!. +1. A friend of mine is fond of putting the following slogan in his signature lines: Life is hard. Wear a helmet.
Durn, screwed that up. !– –! = “two thumbs up” in txt spk.
Not to worry, Al Gore said everybody had upped and left Tuvalu for New Zealand years ago.
As I breathlessly write this Tuvalu and surrounding Atoll isles only have only 6 hrs left before the evil super moon destroys all in it’s deadly gravity grip. I won’t sleep tonight worrying about the Tuvaluanees. Where will they store the $billions in global warming guilt money from the western taxpayers with the Banks and island banksters underwater!
/ Sarc off
Seriously tomorrow will dawn the ocean will be the same depth as yesterday and the sun will shine as usual on the doom, gloom and the users on Tuvalu and the egg on their face warmers!
F.Wulf at 4.43 pm. It is true, that New Zealand and Australia have given assistance, they sent fresh water at one time. An Tuvula asked both countries to take them in but not as refugees, and train them for jobs. Not sure how that went?