Floating Islands

Guest Post by Willis Eschenbach

Much has been written of late regarding the impending projected demise of the world’s coral atoll islands due to CO2-caused sea level rise. Micronesia is suing the Czech Government over CO2 emissions that they claim are damaging their coral atolls via sea level rise. Tuvalu and the Maldives are also repeating their claims of damage from CO2. If the sea level rises much, they say they will simply be swept away.

Recently, here in the Solomon Islands, the sea level rise has been blamed for salt water intrusion into the subsurface “lens” of fresh water that forms under atolls. Beneath the surface of most atolls, there is a lens shaped body of fresh water. The claim is that the rising sea levels are contaminating the fresh-water lens with seawater. On other atolls, increased sea levels are claimed to be washing away parts of the atoll.

In this paper, I will discuss the three inter-related claims that people are making as illustrated above. The claims are:

1. Increasing CO2 causes increased sea level rise.

2. Sea level rise causes salt water to intrude into the freshwater lens

3. Sea level rise gravely endangers low-lying coral atolls like Tuvalu, Kiribati, and the Maldives. A mere 1 metre rise would see them mostly washed away.

I will look at the real causes of the very real problems faced by atoll dwellers. Finally, I will list some practical measures to ameliorate those problems.

And before you ask, how do I know this atoll stuff? For three years I lived on and worked on and had wells dug on and watched the moon rise over and dived in the lagoon and on the reef wall of a coral atoll in the South Pacific … hey, somebody has to … that plus a lot of study and research.

Claim 1. Does increased CO2 cause increased sea level rise?

Short answer, data to date says no. There has been no acceleration the rate of sea level rise. Sea level has been rising for centuries. But the rate of the rise has not changed a whole lot. Both tidal stations and satellites show no increase in the historic rate of sea level rise, in either the short or long term. Fig. 1 shows the most recent satellite data.

Figure 1. Change of sea level over time. Radar data from the TOPEX satellite. The light blue line is sea level with monthly anomalies removed. The interval between data points is usually ten days. The gray line is the 1993-2004 linear trend projected to the end of the timeline. Gaussian average using a 71-point filter. Photo taken at Taunovo Bay Resort, Fiji.

Up until about the end of 2004, there was little change in the rate of sea level rise. Since then the rise has slowed down. The average (dark blue line) does not stray far from the trend (black line) up until 1994. Since then, it is well below the projected trend (gray line). We were supposed to be seeing some kind of big acceleration in the sea level rise caused by increased CO2. Instead, we are seeing a decrease in the rate of sea level rise. So the first claim, that increasing CO2 will cause increased rates of sea level rise, is not supported by the evidence.

Note that I am not saying anything about the future. The rate of sea level rise might go up again. What we can say, however, is that there is no hint of acceleration in the record, only deceleration. Claim 1 is false to date.

Claim 2. Can a sea level rise cause salt water to intrude into the freshwater lens?

Short answer, no. To understand what is really happening with the freshwater lens, we’ll start with the geology. Here is a cross-section of a typical atoll that I drew up.

Figure 2. Typical cross section through a coral atoll. The living coral is in the ring between the dotted green line and the beach. The atoll used for the photo in this example is Tepoto Atoll, French Polynesia.

Note that the sea water penetrates throughout the porous coral rubble base. Because fresh water is lighter than salt water, the freshwater lens is floating on this subsurface part of the ocean. The weight of the fresh water pushes down the surface of the sea water underneath it, forming the bottom of the “lens” shape. The lens is wider where the atoll is wider. The amount of fresh water in the lens is a balance between what is added and what is withdrawn or lost. The lens is only replenished by rain.

The important thing here is that the freshwater lens is floating on the sea surface. It’s not like a well on land, with an underground freshwater source with a water-tight layer below it. There is no underground freshwater source on an atoll. It is just a bubble of water, a rain-filled lens is floating on a sea water table in a porous coral rubble and sand substructure. If there is no rain, the fresh water will eventually slowly mix with the salt water and dissipate. When there is rain, you get a floating lens of fresh water, which goes up and down with the underlying sea water.

So the second claim, that a sea level rise can cause the sea water to intrude into the fresh water lens, is not true either. The fresh water lens floats on the sea water below. A rise in the sea level merely moves the lens upwards. It does not cause salt water to intrude into the lens.

3. Would a sea level rise gravely endanger low-lying coral atolls?

Regarding atolls and sea level rise, the most important fact was discovered by none other than Charles Darwin. He realized that coral atolls essentially “float” on the surface of the sea. When the sea rises, the atoll rises with it. They are not solid, like a rock island. They are a pile of sand and rubble. There is always material added and material being lost. Atolls exist in a delicate balance between new sand and coral rubble being added from the reef, and atoll sand and rubble being eroded by wind and wave back into the sea or into the lagoon. As sea level rises, the balance tips in favor of sand and rubble being added to the atoll. The result is that the atoll rises with the sea level.

Darwin’s discovery also explained why coral atolls occur in rings as in Fig. 2 above. They started as a circular inshore coral reef around a volcanic rock island. As the sea level rose, flooding more and more of the island, the coral grew upwards. Eventually the island was drowned by the rising sea levels, and all that is left is the ring of reef and coral atolls.

Why don’t we see atolls getting fifty feet high? Wind erosion keeps atolls from getting too tall. Wind increases rapidly with distance above the ocean. The atolls simply cannot get taller. The sand at that elevation is blown away as fast as it is added. That’s why all atolls are so low-lying.

When the sea level rises, wind erosion decreases. The coral itself continues to grow upwards to match the sea level rise. Because the coral continues to flourish, the flow of sand and rubble onto the atoll continues, and with reduced wind erosion the atoll height increases by the amount of the sea level rise.

Since (as Darwin showed) atolls float up with the sea level, the idea that they will be buried by sea level rises is totally unfounded. Despite never being more than a few metres tall, hey have survived a sea level rise of up to three hundred plus feet (call it a hundred metres) within the last twenty thousand years. Historically they have floated up higher than the peaks of drowned mountains.

So the third claim is not true either. Atolls are createdby sea level rise, not destroyed by sea level rise.

What is the real cause of salt water in the lens?

Given that the salt water intrusion can’t be a result of sea level rise (because the lens is floating), why is there salt water in the islanders’ wells? Several factors affect this. First and foremost, the fresh water lens is a limited supply. As island populations increase, more and more water is drawn from the lens. The inevitable end of this is that the water in the wells gets saltier and saltier. This affects both wells and plants, which draw from the same lens. It also leads to unfounded claims that sea level rise is to blame.

The second reason for salt water intrusion into the lens is a reduction in the amount of sand and rubble coming onto the atoll from the reef. When the balance between sand added and sand lost is disturbed, the atoll shrinks. When the atoll shrinks, the lens shrinks.

The third reason is that roads and airstrips and changes in land use and land cover has reduced the amount of rain making it to the lens. Less freshwater in, more saltwater in.

What is the real cause of loss of beach and atoll land?

An atoll is not solid ground. It is is not a constant “thing” in the way a rock island is a thing. An atoll is a not-so-solid eddy in a river of sand and rubble. It is an ever-changing body constantly replenished by a (hopefully) unending stream of building materials. It is a process, not a solid object. On one side, healthy reef plus beaked coral-grazing fish plus storms provide a continuous supply of coral sand and rubble. This sand and rubble are constantly being added to the atoll, making it larger. At the same time, coral sand and rubble are constantly being eaten away by waves and blown away by the wind. The shape of the atoll changes from season to season and from year to year. It builds up on this corner, and the sea washes away that corner.

So if the atoll is shrinking, there’s only a few possibilities. Erosion may have increased. The supply of sand and rubble, the raw atoll construction materials, may have decreased. Currents may have changed from reef damage, dredging, or construction.

Water erosion and current changes are increased by anything that damages or changes the reef. That thin strip of living coral armor is all that stands between a pile of sand and the endless waves. When the reef changes, the atoll changes.

Erosion is also caused by a variety of human activities. Road and path building, house construction, ground cover change, clearing of channels through the reef, the list is long.

The reduction in the supply of coral sand and coral rubble, however, is harder to see. This reduction has two main causes – using of coral for building, and killing the wrong fish. The use of coral as a building material in many atolls is quite common. At times this is done in a way that damages the reef. Anything that affects the health of the reef affects how much atoll building material it produces each year. This is the somewhat visible part of the loss of building materials, the part we can see.

What goes unremarked is the loss of the reef sand, which is essential for the continued existence of the atoll. The major cause for the loss of sand is the indiscriminate, wholesale killing of parrotfish and other beaked reef-grazing fish. A single parrotfish, for example, creates around a hundred kilos of coral sand per year. Parrotfish and other beaked reef fish create the sand by grinding up the coral with their massive jaws, digesting the food, and excreting the ground coral.

Beaked grazing fish are vital for overall coral health, growth, and production. This happens in the same way that pruning makes a tree send up lots of new shoots. The constant grazing by the beaked fish keeps the corals in full production mode. This greatly increases the annual production of coral for sand and rubble.

Unfortunately, these fish sleep at night, and thus are easily wiped out by night divers. The invention of the diving flashlight has meant that their populations have plummeted in many areas in recent years. Result? Less sand means less beaches, and means more claims of “CO2 is to blame, you can see the damage!”.

Some Practical Suggestions

What can be done to turn the situation around for the atolls? From the outside, not a whole lot. Stopping the Czechs from burning coal won’t do a damned thing. From the outside, we can offer only assistance. The work needs to occur on the atolls themselves.

There are, however, a number of low-cost, practical steps that atoll residents can take to preserve and build up their atolls, and protect the fresh water lens. In no particular order these are:

1. Stop having so many kids. An atoll has a limited supply of water. It cannot support an unlimited population. Enough said.

2. Catch every drop that falls. On the ground, build small dams in any watercourses to encourage the water to soak in to the lens rather than run off to the ocean. Put water tanks under every roof. Dig “recharge wells”, which return filtered surface water to the lens in times of heavy rain. Catch the water off of the runways. On some atolls, they have put gutters on both sides of the airplane runway to catch all of the rainwater falling on the runway. It is collected and pumped into tanks. On other atolls, they let the rainwater just run off of the airstrip back into the ocean …

3. Conserve, conserve, conserve. Use seawater in place of fresh whenever possible. Use as little water as you can.

4. Make the killing of parrotfish and other beaked reef grazing fish tabu. Stop fishing them entirely. Make them protected species. The parrotfish should be the national bird of every atoll nation. I’m serious. If you call it the national bird, tourists will ask why a fish is the national bird, and you can explain to them how the parrotfish is the source of the beautiful beaches they are walking on, so they shouldn’t spear beaked reef fish or eat them. Stop killing the fish that make the very ground underfoot. The parrotfish and the other beaked reef-grazing fish are constantly building up the atoll. Every year they are providing tonnes and tonnes of fine white sand to keep the atoll afloat in turbulent times. They should be honored and protected, not killed. Caring for the reef is the single most important thing you can do.

5. Be cautious regarding the use of coral as a building material. The atoll will be affected if anything upsets that balance of sand added and sand lost. It will erode if the supply of coral sand and rubble per year starts dropping (say from reef damage or extensive coral mining or killing parrotfish) or if the total sand and rubble loss goes up (say by heavy rains or strong winds or human erosion or a change in currents).

So when coral is necessary for building, take it sparingly, in spots. Take dead or dying coral in preference to live coral. Mine the deeps and not the shallows. Use hand tools. Leave enough healthy reef around to reseed the area with new coral. A healthy reef is the factory that annually produces the tonnes and tonnes of building material that is absolutely necessary to keep the atoll afloat. You mess with it at your peril.

6. Reduce sand loss from the atoll in as many ways as possible. This can be done with plants to stop wind erosion. Don’t introduce plants for the purpose. Encourage and transplant the plants that already grow locally. Reducing water erosion also occurs with the small dams mentioned above, which will trap sand eroded by rainfall. Don’t overlook human erosion. Every step a person takes on an atoll pushes sand downhill, closer to returning to the sea. Lay down leaf mats where this is evident, wherever the path is wearing away. People wear a path, and soon it is lower than the surrounding ground. When it rains, it becomes a small watercourse. Invisibly, the water washes the precious sand into the ocean. Invisibly, the wind blows the ground out from underfoot. Protect the island from erosion. Stop it from being washed and blown away.

7. Monitor and build up the health of the reef. You and you alone are responsible for the well-being of the amazing underwater fish-tended coral factory that year after year keeps your atoll from disappearing. Coral reseeding programs done by schools have been very successful. Get the kids involved in watching and recording and photographing the reef. Remind the people that they are the guardians of the reef. Talk to the fishermen.

8. Expand the atoll. Modern coastal engineering has shown that it is often quite possible to “grow” an atoll. The key is to slow down the water as it passes by. The slower the water moves, the more sand drops out to the bottom. Slowing the water is accomplished by building low underwater walls perpendicular to the coastline. These start abovewater, and run out until the ends are a few metres underwater. Commercially this is done with a geotextile fabric tubes which are pumped full of concrete. See the references for more information. In the atolls the similar effect can be obtained with “gabbions”, wire cages filled with blocks of dead coral. Wire all of the wire cages securely together in a triangular pattern, stake them down with rebar, wait for the sand to fill in. It might be possible to do it with old tires, fastened together, with chunks of coral piled on top of them. It will likely take a few years to fill in.  This triangular shape does not attempt to stop the water currents. Think of it as a speed bunp. It just slows the currents down and directs them toward the beach to deposit their load of sand. Eventually, the entire area fills in with sand.

Of course to do that, you absolutely have to have a constant source of sand and rubble … like for example a healthy reef with lots of parrotfish. That’s why I said above that the most important thing is to protect the fish and the reef. If you have a healthy reef, you’ll have plenty of sand and rubble to keep the atoll afloat forever. If you don’t, you’re in trouble.

Coral atolls have proven over thousands of years that, if left alone, they can go up with the sea level. And if we follow some simple conservation practices, they can continue to do so and to support atoll residents. But they cannot survive an unlimited population increase, or unrestricted overfishing, or overpumping the water lens, or unrestrained coral mining. Those are what is killing the atolls, not the same sea level rise that we’ve had for the last hundred years.

FURTHER REFERENCES:

On global sea level rise levelling off: University of Colorado at Boulder Sea Level Change,  http://sealevel.colorado.edu

On Darwin’s discovery: Darwin, C., The Autobiography of Charles Darwin 1809-1882, 1887

“No other work of mine was begun in so deductive a spirit as this; for the whole theory was thought out on the west coast of S. America before I had seen a true coral reef. I had therefore only to verify and extend my views by a careful examination of living reefs. But it should be observed that I had during the two previous years been incessantly attending to the effects on the shores of S. America of the intermittent elevation of the land, together with the denudation and deposition of sediment. This necessarily led me to reflect much on the effects of subsidence, and it was easy to replace in imagination the continued deposition of sediment by the upward growth of coral. To do this was to form my theory of the formation of barrier-reefs and atolls.” (Darwin, 1887, p. 98, 99)

On the results of coral mining and changing the reef: Xue, C. (1996) Coastal Erosion And Management Of Amatuku Island, Funafuti Atoll, Tuvalu, 1996, South Pacific Applied Geoscience Commission (SOPAC), http://conf.sopac.org/virlib/TR/TR0234.pdf This atoll was cited by the Sierra Club as an example of the dangers of sea level rise. The truth is more prosaic.

On the same topic: Xue, C., Malologa, F. (1995) Coastal sedimentation and coastal management of Fongafale, Funafuti, Tuvalu, SOPAC Technical Report 221

More information on how parrotfish increase reef production: http://www.esajournals.org/doi/abs/10.1890/1051-0761(2006)016%5B0747:TIOEGS%5D2.0.CO%3B2

On the cause of erosion in Tuvalu: Tuvalu Not Experiencing Increased Sea Level Rise, Willis Eschenbach, Energy & Environment, Volume 15, Number 3, 1 July 2004 , pp. 527-543, available here (Word doc).

On expanding island beaches: Holmberg Technologies, http://www.erosion.com/

On the dangers of overpopulation: Just look around you …

——————————————————-

[UPDATE June 3, 2010] Other scientists are catching up with me (emphasis mine).

Global and Planetary Change, Article in Press, Accepted Manuscript, doi:10.1016/j.gloplacha.2010.05.003

The dynamic response of reef islands to sea level rise: evidence from multi-decadal analysis of island change in the central pacific

Arthur P. Webb a, and Paul S. Kench b; a South Pacific Applied Geoscience Commission, SOPAC. Fiji; b School of Environment, The University of Auckland, Private Bag 92019, Auckland, New Zealand

Received 22 February 2010; accepted 13 May 2010. Available online 21 May 2010.

Abstract

Low-lying atoll islands are widely perceived to erode in response to measured and future sea level rise. Using historical aerial photography and satellite images this study presents the first quantitative analysis of physical changes in 27 atoll islands in the central Pacific over a 19 to 61 year period. This period of analysis corresponds with instrumental records that show a rate of sea level rise of 2.0 mm.y-1 in the Pacific.

Results show that 86% of islands remained stable (43%) or increased in area (43%) over the timeframe of analysis. Largest decadal rates of increase in island area range between 0.1 to 5.6 hectares. Only 14% of study islands exhibited a net reduction in island area.

Despite small net changes in area, islands exhibited larger gross changes. This was expressed as changes in the planform configuration and position of islands on reef platforms. Modes of island change included: ocean shoreline displacement toward the lagoon; lagoon shoreline progradation; and, extension of the ends of elongate islands. Collectively these adjustments represent net lagoonward migration of islands in 65% of cases.

Results contradict existing paradigms of island response and have significant implications for the consideration of island stability under ongoing sea level rise in the central Pacific.

First, islands are geomorphologically persistent features on atoll reef platforms and can increase in island area despite sea level change.

Second; islands are dynamic landforms that undergo a range of physical adjustments in responses to changing boundary conditions, of which sea level is just one factor.

Third, erosion of island shorelines must be reconsidered in the context of physical adjustments of the entire island shoreline as erosion may be balanced by progradation on other sectors of shorelines. Results indicate that the style and magnitude of geomorphic change will vary between islands. Therefore, Island nations must place a high priority on resolving the precise styles and rates of change that will occur over the next century and reconsider the implications for adaption.

In other words, the islands are floating upwards with the sea level rise, just as I had said. So for those in the comments section who think I’m just making this up … think again. In particular, the final comment by lkrndu22 says that I am “hoist by my own petard” because ocean acidification has already caused “evident and severe” damage … ‘fraid not. The islands continue to rise. The main cause of damage to the corals is … coral mining and killing the fish. And islands where that is happening are in danger, as I indicated above.

But sea level rise? The atolls have lived through that for thousands of years without damage.

Advertisements

  Subscribe  
newest oldest most voted
Notify of
Ross

Willis, James and friends- OT slightly- in researching an article I am writing myself I have just come across an amazing observation by Francis Bacon in 1620 that to me sums up the whole Climategate, IPCC, Himalayagate and all the other gates that I would like to share with you:
“Those who have taken upon them to lay down the law of nature as a thing already searched out and understood, whether they have spoken in simple assurance or professional affectation, have therein done philosophy and the sciences great injury. For as they have been successful in inducing belief, so they have been effective in quenching and stopping inquiry; and have done more harm by spoiling and putting an end to other men’s efforts than good by their own.” (Bacon)
The full text is in translation here: http://www.constitution.org/bacon/nov_org.htm
Just something to reflect on. Best wishes and thank you for all your hard work.

chili palmer

Re Obama’s speech, reference to climate change science, Mary Kissel of Asia Wall St Journal interviewed on a radio program was asked if other countries view (man caused) climate change as settled science as Obama does. She said not at all, other countries don’t accept it at all, the only places it’s still accepted are the White House and Australia.

toyotawhizguy

Persons that take up residence on an atoll are just asking for trouble. Sooner or later they will have to deal with a deadly Tsunami. Eventually, mother nature will take care of the overpopulation problem in one way or another.
“The Most Important Video You’ll Ever See” (part 1 of 8)

BOP

Thank you very much. Good information.
Ben

Gary Hladik

“For three years I lived on and worked on and had wells dug on and watched the moon rise over and dived in the lagoon and on the reef wall of a coral atoll in the South Pacific…”
At this point I nearly stopped reading out of sheer jealousy, but fought it down and was rewarded with a fascinating article. Well done, Willis.
I’m still jealous, though.

JaneHM

Another contributor to shrinking is the shrinking of the volcano as it continues to cool

Ray Boorman

Willis, all you have written is common sense to a thinking person – which is why it will be ignored, or ridiculed, by those with a vested interest in maintaining the AGW business model.

Geoff Sherrington

Willis, Please be careful, you might set another precedent, because this is a mixture of observation, deduction and common sense. As one who grew up with grains of tropical sand between my toes, I have no argument with any statement above. Thank you for putting the parrotfish in contect. I had not thought of them as quite so important.
Yep, you are quite right. The repeated process of walking over a sand track can make a rivulet. That is more relevant to the health of the atoll than Czech CO2.

jerry

One side effect of road, airstrip and housing construction is an increase in water available to go into the ground and a decrease in the natural extraction from the ground.
Building roads and houses removes trees and brush – which are natural pumps drawing water from the water table and delivering it to the air by evapo-transpiration. This effect can be quite significant – equivalent to metres of groundwater in a year.
The new ‘hard’ surfaces also make catchment more efficient – assuming it is channeled to soak wells. Where vegetation stands there is usually a prolonged delay in rainwater entering the groundwater system. This gives a much longer time for it to evaporate.

Baike

Fascinating read.
If your post is accurate, how can it be that the leaders of these atolls can make claims that they’re sinking due to sea level rises and be taken seriously on the international stage (regardless of the cause of those sea level rises)?
Is the culture of fear so great that one is cautious of even correcting the most obvious of mistakes? Or is ignorance/laziness the dominating factor?
[REPLY – Follow the money! ~ Evan]

Moemo

I will go forth and edumacate my friends on the truth regarding these special places called, Atols.
Great piece Willis and thank you Anthony for bringing it to us here.

Clive

Willis
Thank very much for this informative article.
I’ve made a PDF for future reference.
Clive

Fascinating post, thanks, Willis!

par5

A population may not exceed its annual rainfall. Good stuff- thanks Willis.

Bulldust

Love it Willis. What amazes me is this… how exactly did the Micronesians determine that it was Czech Republic’s carbon causing them harm? Yes, I am being facetious, but theirs is an ambit claim so I think I am justified. The IPCC has a lot to answer for because it has encouraged a lunatic fringe in society to pursue ridiculous actions such as these.
Hopefully common sense will prevail.

Kasmir

Good post Willis, but to expand on what you wrote, the central reason that atolls don’t drown stems from the growth rate of the reef-building corals. “Modern” stony corals, particularly the ubiquitous Acropora genus, grow at about 6″ per year in tropical conditions. That’s about 50X the average sea level rise we’ve been seeing, so the reef tops easily keep up with the sea level rise. Wave action especially during storms does indeed regularly throw coral rubble (and sometimes live reef) atop the living reef above sea level, where it rapidly erodes as you describe, sustaining the intermittent ring of low-lying sandy islands that make up an atoll.
So it would take an incredibly enormous increase in sea level rise to “drown” live coral reefs. It’s also worth observing that all corals are colonial animals and also sexually reproduce via sporulation. and the spores can travel long distances to establish new colonies. Hence coral have been able to cope with many, many dramatic and even abrupt climate changes in earth’s history.
Particular configurations of coral colonies are always growing and renewing themselves, and are fundamentally transient. the Great Barrier Reef is about the same age as the Great Pyramids. As a class, coral has been around for 500m+ years and has survived numerous extinction events. Coral is quite resilient. The principle impact of any further global warming would be to extend its range to higher latitudes.

Retired Engineer

Common sense ecology? Without lawyers? Perish the thought!
If it were not such a bad joke, Eschenbach deserves a Nobel Prize.
(no insult intended)
What might happen if we applied this kind of logic to all our problems?

Mike McMIllan

I’ve been watching the Colorado sea level site for several years now, The rise leveled off in 2005 from its long-term rate of 3.2 mm/year down to around 2. The last couple entries have it climbing back up again. By 2100, the sea should rise almost a foot. I think those busy little polyps could keep up with it.

wayne

In claim 2: “The amount of fresh water in the lens is a balance between what is added and what is withdrawn or lost. ”
and
“The lens is only replenished by rain.”
Rain is the only addition, but bet multiple hotel pools and hundreds of rooms with high pressure showers tend to suck that sea water right up into those lens pools as the fresh water is sucked out for the holiday vacationers!

Chris Polis

I’d say this has to be one of the best pieces of work I have read here in the last few months. Informed, comprehensive, and practical. Props.

stumpy

As an environmental engineer who specialises in hydrogeology, hydrology and hydraulics I find it hard to believe anyone with half a brain can think sea level rise will lead to saline intrusion – I hope its not scientists saying garbage!
The sea forms the downstream boundary condition and generates a tailwater effect upon which the attenuated rainfall sits above, with the flow path, porosity and frictional losses setting the hydraulic grade and drain down time between rainfall. The factors that will influence this is as was correctly stated increased drawdown or reduced rainfall / increased evapotranspiration or possibly increases in tidal range leading to increase saline intrution in coastal areas during high tide.

PeterB

Thanks Willis, a great read.
I feel quite a lot of sympathy for people living in places such as this, being told (with what appears to be a great deal of authority by scientists and NGOs) that their homes and livelihood are at risk by the actions of others. Unlike the Indian government in the case of the glaciers, they probably don’t have the resources to falsify the claims themselves.

wayne

Hey, someone forgot all of the hotels around the beaches when the drew that atoll illustation!

Toto

The cheapest solution to the islanders’ fears of rising sea level would be to grant them American citizenship.

yonason

That sea level anomaly data doesn’t appear to square with this.
http://nzclimatescience.net/images/PDFs/paperncgtsealevl.pdf
But I guess satellites, measuring sea level from a few hundred kilometers up, are more accurate than ‘on-site’ data collection? …you know, like ARGO temps vs those measured by satellite which are preferred by warmers.

Roger Carr

Floating Islands has a compelling simplicity that belies its scholarship. Or is this really how scholarship should always be presented?
Thank you, Willis Eschenbach, for both education and enchantment… and tools to use against misinformation and hysterics.

stan stendera

WOW! Good, Good stuff.

Great article. Good science and practical advice. What more can one ask for?
Well, I guess I can ask for one more thing – Do you need an assistant to live on those atolls?

wayne

Willis:
More seriously, with the increased tourism to many islands, they are bound to have an increased drain on local resources, such as fresh water. Are the hotels and tourism related housing replenishing some of this drain through desaltination or water imports? Are they carrying their load or just adding to the island’s fresh water problems?

Deadman

Thanks for that.
A few suggestions:
“The lens is only replenished by rain” should be “The lens is replenished only by rain.”
In “Despite never being more than a few metres tall, hey have survived…”, ‘hey’ should be ‘they’.
In “The third reason is that roads and airstrips and changes in land use and land cover has…”, ‘has’ should be ‘have’.
“This reduction has two main causes – using of coral for building, and killing the wrong fish.” I’d prefer something like: “This reduction has two main causes: the use of coral for building, and killing the wrong fish.”
“This is the somewhat visible part of the loss of building materials, the part we can see.” Well, yes, we can see visible things, but somewhat?
“Less sand means less beaches” should be “Less sand means fewer beaches”.
“Of course to do that, you absolutely have to have a constant source of sand and rubble … like for example a healthy reef with lots of parrotfish.”
I’d prefer something like: “Of course, to do that, you absolutely have to have a constant source of sand and rubble—which a healthy reef with lots of parrotfish has.”
In “Those are what is killing the atolls,” ‘is’ should be ‘are’, but I’d prefer: “Those things are killing the atolls”.

Dave Harrison

What do the IPCC reports say on this? – I do hope that they have not depended on the WWF for information on coral islands too.

Andy in Christchurch NZ

This has been a very informative article. Thank you.
We in NZ get a lot of pressure on our responsibilty to Pacific Islands due to “Climate Change” and this succinctly puts it all in perspective.
OT from Ross, commenter #1, the quote from Bacon sums it up for me. This is not about whether we care about saving the planet, ( the usual warmist counterstrike) but whether we care about open and honest scientific and intellectual discourse. Brilliant!

tokyoboy

I posted this days ago on another thread, but cannot resist to post it again:
http://www.data.kishou.go.jp/shindan/a_1/sl_trend/sl_trend.html
Caption: Sea level trend around Japan for 1906-2008.
Comment by our Meteorological Agency: No clear trend during the 103 years, and a 20-year oscillation is evident.
You see that in the satellite age (1993-present), the curve is very similar to that on the Willis’ Figure, i.e., a 4-cm rise and a leveling-off trend over the 18 years or so.

Even according to top IPCC predictions for sea level rise, all of Prunéřov power plant will increase the sea levels by 42 microns in 25 years.
http://motls.blogspot.com/2009/12/micronesia-will-be-sunk-by-czech-coal.html
The Micronesian environment minister has revealed in the interview for Czech counterpart of the Wall Street Journal that the whole protest was inspired by Greenpeace who are also sending them all the data and technical details (probably including the format and legal issues):
http://motls.blogspot.com/2010/01/micronesian-minister-greenpeace-tells.html
Greenpeace means Greenpeace CZ, and its boss for energy and climate campaigns, Mr Jan Rovenský, who was my friend for 2 weeks back in 1988 when we were teaching Czech to the Russians in our, Pilsen’s twin city Yekaterinburg, then Sverdlovsk.
Rovenský sent a similar proposal to sue the Czech Republic to all island countries in the world – but he said that he was still shocked that one of them, Micronesia, actually said Yes.
Pretty good case of high treason for Jan could be made.

J.Hansford

I agree with most of that…. Just the fishery part I have problems with.
You can harvest any fast growing fishes with little danger of over fishing…. Just needs to be done right, is all.
People aren’t stupid once they know the reasoning…. Only bureaucrats think people are stupid herd animals worthy of only conning in this direction and then in that direction….
Anyway…. What’s better than having the national bird as the national dish also? 🙂

Willis Eschenbach

yonason (22:13:36)

That sea level anomaly data doesn’t appear to square with this.
http://nzclimatescience.net/images/PDFs/paperncgtsealevl.pdf
But I guess satellites, measuring sea level from a few hundred kilometers up, are more accurate than ‘on-site’ data collection? …you know, like ARGO temps vs those measured by satellite which are preferred by warmers.

Your paper references the SEAFRAME dataset, which is a good one. SEAFRAME is a project which has put very accurate tide gauges around the Pacific.
Ollier (your reference) draws very different conclusions from the SEAFRAME data than I do. He says they show no rise. I say, and the SEAFRAME folks also say, that sea level is rising in the South Pacific, just as it is (on average) globally.
SEAFRAME data for Tuvalu is available here.

yonason (22:13:36) :
That sea level anomaly data doesn’t appear to square with this.
http://nzclimatescience.net/images/PDFs/paperncgtsealevl.pdf
But I guess satellites, measuring sea level from a few hundred kilometers up, are more accurate than ‘on-site’ data collection?
—-
Well, er, yes.
See, unlike the prejudged (and biased) sources that AGW advocates invent, the satellites we “realists” prefer are unbiased and much more accurate than a surface measurement of RELATIVE beach heights tampered by up and down land movements, beach erosion, water table movements (from pumping and recharging) changing the land height, land erosion, tides, winds, storms, local flooding, etc.

Baa Humbug

I know (knew) nothing about the dynamics of coral atolls. How refreshing to be able to read a reasonable and logical piece. Yet another from Willis. Thankyou sir for broadening my horizon.
I couldn’t help but visualize Ian Fry of Tuvalu (an Australian actually) almost crying in his impassioned plea to the COP 15 in December. Here is the video…
(the cry starts at 3min mark)

And here is what the IPCC says in it’s synthesis report…
“By the 2080s, many millions more people than today are projected
to experience floods every year due to sea level rise. The
numbers affected will be largest in the densely populated and
low-lying megadeltas of Asia and Africa while small islands
are especially vulnerable (very high confidence). {WGII 6.4, 6.5,
Table 6.11, SPM}
Willis I would have thought Islanders would have had a good understanding of their atolls. Do they? If so, their demands are just political opportunism. If not, well…I’m surprised. Usually indigenous peoples know their environment quite well.

Willis Eschenbach

J.Hansford (23:18:38)

I agree with most of that…. Just the fishery part I have problems with.
You can harvest any fast growing fishes with little danger of over fishing…. Just needs to be done right, is all.
People aren’t stupid once they know the reasoning…. Only bureaucrats think people are stupid herd animals worthy of only conning in this direction and then in that direction….
Anyway…. What’s better than having the national bird as the national dish also? 🙂

The problem was advancing flashlight technology. Parrotfish have strange sleeping habits. They find a niche in the reef. They spit out some kind of strange mucus which envelops their entire bodies. This magically makes them invisible to every creature in the night-time ocean … except humans with dive lights. In my youth before I gave up spearfishing I used to swim right up until the spear point was almost touching them, and pull the trigger.
This gives them a much, much greater danger of overfishing than the fish you mention above. You can wipe them out altogether too easily.

Al Gore's Holy Hologram

Water usage is increasing thereby offsetting increases in ice melt, and that usage should continue to increase as we irrigate dry lands and deserts which are home to the poorest on the planet.
The racist, elitist, imperialist powers that be and their even worse cohorts in the Green movement better make it or allow it to happen.

Peter of Sydney

Really good article. Why doesn’t the IPCC come up with such detailed and clearly explained analysis? Ah yes I forgot – it’s a political organization, not a scientific one so it’s analysis are based on spin and cherry picked and sometimes corrupted data.

Chris Schoneveld

Very good post!
On September 12, 2008, the International Herald Tribune published (my heavily edited, since I also explained the importance of the rubble and sand build-up) letter to the editor:
“A self-inflicted problem
In “Climate change: With millions under threat, inaction is unethical” (Views, Sept. 10) the president of the Maldives, Maumoon Abdul Gayoom, contends that the Maldives are threatened by climate change, yet he fails to acknowledge that coral islands have survived during a rise in sea levels of 120 meters since the last ice age.
Under natural conditions, coral is perfectly able to grow upwards, keeping pace with any relative rise in sea levels.
If someone has to be blamed for the eventual demise of any of the Pacific or Indian Ocean coral islands, it is the inhabitants themselves. They are the ones who are destroying the natural coral habitat by creating roads and buildings, allowing bad fishing practices and many forms of pollution. With dead coral, these islands have no natural mechanism to keep them above water. The inconvenient truth is that these islands are not sustainable under permanent human inhabitation.”

Another great article.
Readers need to put sea levels into their historic perspective-just like temperature recors, a snapshot since satellites began do not reveal the full picture.
Chapter five of AR4 demonstrates the manipulation (and errors) that went on in order to create a base line figure-it was derived from only three North European tide station data which was heavily interpolated and adjusted.
Records show higher levels existed at the time of medieval castle building on coasts-for example Harlech castle in Wales has a sea gate no longer accesible to the sea. In Roman times the sea level was also generally higher and around three thousand years before that seems to have been the high point for sea levels.
The sea level discuission is greatly complicated by different rates of change around the world caused by local factors such as development, earthquakes, isostatic depresion or rise of land, deposition, erosion etc.
There is simply no sign at all that levels will rise by more than a few inches over the coming century.
Read Chapter five if you want to see a fudge of figures greater than the Hockey stick.
tonyb

Michael

The Davos world economic forum in Switzerland looks like it is being snowed in. Wouldn’t it be ironic it the pushers of the world wide carbon tax got stuck there because of global cooling?

Baa Humbug

Here is the Tuvaluan representative calling for help as the Island sinks. I think it’s Lubos who got the call 🙂
(I hope the mods let me get away with this) lol

Varco

Willis, one of the most informative posts I have read in a while. Congratulations.

Mattb

Wow – amazing – have you thought of publishing this in a real journal so that genuine research experts in the field can comment on it, or learn from it?

Great post, good job Willis. My kneejerk skepticism compels me to ask, however, what about the surf? Doesn’t that constant wave pounding on the reef grind up a fair amount coral, with or without the parrot fish? Can you separate the hydraulic mechanical demolition from the piscine demolition and account for each? I think it is a lovely tale, atolls are parrot fish-dependent and all, but being a cold blooded natural doubter, I have a hard time swallowing it whole.
Irregardless, I liked your essay and can swallow 99% of it.

toyotawhizguy (21:04:07) :

Persons that take up residence on an atoll are just asking for trouble. Sooner or later they will have to deal with a deadly Tsunami. Eventually, mother nature will take care of the overpopulation problem in one way or another.
“The Most Important Video You’ll Ever See” (part 1 of 8)

Wow! Thank you so much fo that, toyotawhizguy.
As a born mathematician (we are born, not made) the argument is so obvious I am gobsmacked that I had not seen it before. It matters not a jot if fossil fuel deposits are actually increasing. Once we find out they are not, once we realise the finite resource is really finite, we have a really, really, short time before it ends.
The argument is that say we put some bacteria in a bottle at 11:00, and it is full at 12:00, when did the bottle ‘seem’ crowded? at 11:56 it was ‘almost empty’. At 11:59 it was still half empty.
The same is true of any finite resource. At 7% increase in consumption (and I think China will make that a joke), we use the same amount every decade as has EVER been used before. Once we hit 50% of all the fossil fuels, we have 10 more years and then no more at all. None. That is just at a mere 7% increase a year.
This seriously call for a really hard look at some kind of resource that is not finite. What’s that word again? Oh yes, “renewable”.
Now that is an argument I can take on board. Sod CO2!

Geoff Sherrington

Up above it says “all corals are colonial animals and also sexually reproduce via sporulation”
I’m a colonial animal. Sure would like to try that sporelation thingo. Do you need leather and [snip]?