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 saltwater intrusion into the subsurface “lens” of freshwater 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 freshwater 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 two interrelated claims that people are making as illustrated above. The claims are:
1. Sea level rise causes salt water to intrude into the freshwater lens
2. Sea level rise gravely endangers low-lying coral atolls like Tuvalu, Kiribati, and the Maldives. A mere 1-meter 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. 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 1. 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. Click image to embiggen.
Note that the seawater 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 freshwater pushes down the surface of the seawater underneath it, forming the bottom of the “lens” shape. The lens is wider in areas 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 floating on a seawater table in a porous coral rubble and sand substructure. If there is no rain, the freshwater 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 seawater.
So the second claim, that a sea level rise can cause the sea water to intrude into the freshwater lens, is not true either. The freshwater lens floats on the seawater below. A rise in the sea level merely moves the lens upwards. It does not cause salt water to intrude into the lens.
Claim 2. 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 (or equally, if the island sank), 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 meters tall, they have survived a sea level rise of up to three hundred plus feet (call it a hundred meters) 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 created by sea level rise, not destroyed by sea level rise.
What is the real cause of salt water in the lens?
Given that the saltwater intrusion can’t be a result of sea level rise (because the lens is floating), why is there saltwater in the islanders’ wells? Several factors affect this. First and foremost, the freshwater 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 saltwater 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 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 reefs 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 are 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 and bony throats, 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 freshwater 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 into 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 rate of 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 (PDF doc).
On expanding island beaches: Holmberg Technologies, http://www.erosion.com/
On the atolls getting larger: Global-scale changes in the area of atoll islands during the 21st century
On the dangers of overpopulation: Just look around you …
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[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.
Ralph (01:39:35) :
Ancient shorelines in a tectonically active area like the Mediterranean have only a very vague relationship to sea-level since the land moves (up or down) much faster than the sea level. For example in Italy the shoreline from the previous interglacial (c. 120,000 years ago) is now found from +190 meters (625 feet) to -130 meters (425 feet) and virtually any level in between. This implies average long-term rates of rise or subsidence as high as 1.5 meters per millenium (1.5 mm/yr), and short-term figures are certainly much higher.
Willis, that report on Tuvalu you linked is by an NGO for a Department concerned with aid. I have not read it fully. It could be biased towards AGW. However, the sea level graphs look very similar to that of Ollier. There is some Australian researcher at ANU who represented Tuvalu at Coepenhavn ( more or less how the Danish would pronounce it). I think he was paid to be there by the Australian Government. he may have been a contributor.
A better report by the Aust. Govt. BOM is here http://www.bom.gov.au/oceanography
Called South Pacific Sea level and climate Monitoring Project, Sea Level summary report July20089-June2009. There are some interesting details about ENSO and PDO. You will see a much more detailed graph on Tuvalu which shows no increase in sea level since 1998. It is good see that in some parts of BOM there are still objective scientists.
regards
Excellent analysis, and especially for the Darwinianconnection. But, did not Darwin also add that atolls built around extinct volcanic rims will eventually sink with the volcano, due to tectonic forces? As far as I am aware, his theory has not been disproved and many such islands are in very active tectonic zones. A geological interpretation of the current situation would be welcome.
“supercritical (02:00:30) :
If they get the compensation from the Czech ‘John Frum’ they are asking for, they will merely carry on wrecking their environment, and go the way of the Easter Islanders.”
One must remember the Easter Islanders were driven by a strong desire to please their “Gods”. They stripped their land of trees in order to transport and errect the “statues”. The island is littered with semi-finished “idols” and the evidence of their demise.
There is plenty of evidence on the island of a certain level of chaos. It reminds me of the Moche in what is now Peru and what happened in Egypt.
People were sacrifcing their environment *AND* themselves to the “gods”. When the “gods” did not respond, well, societies destroyed themselves.
Idols, spirits and gods are human concepts. Global climate change will not stop this belief most people want to think of an afterlife and be to “saved” (AGW etc).
I really wish people would just get their heads around the fact we’re just monkeys, and not much smarter either. *wink*
RE: MY yonason (02:54:31)
I just realized I misread the scale. They only go back to 1993, not 1992.
However, the primary problem remains.
The linear fit of your graph looks good from 1993 to 2004 (same range as the paper I sited). That’s a problem for me because in my ref., the slope also fits the data well, and it’s slope is 2.8/yr. Compare that with your ref., which looks like about 3.5/year.
Something is not right here. Can you show me if, and where I made a mistake?
Superb article. One thing:the volcanic island also sinks into the seafloor so it is a combo of rising sealevel and subsidence. Certainly the major factor osubsidence can’t be blamed on CO2 and the phenomenon itself even more strongly supports your view of the compensation ofliving coral to change in sealevel.
…and not a peer reviewed one, eh? 🙂
About that Czech Prunerov coal plant: The owners (CZE) want to close part of it and rebuild the rest. Our Green ministry is not happy with the technology they want to use (38% effectivity) and forces them to use the “best” one, which, however, has 41% and increases the renovation price about 50%. CZE says, that the ‘best” technology is based on black coal and not on the low-quality brown coal which would never produce the 41% value and that the plant also supplies heat, which increases the overall effectivity to 50%. Plus – the coal would be probably finished in 25 years and the “best” technology would never pay itself back in that time span.
So I presume that the Green Ministry started to pressure CZE using that Greenpeace-induced Micronesia letter. However, CZE said that in case they would not get permission for rebuilding the plant with their chosen technology, they would simply let it run as it is, with all the excessive CO2 AND more of dust particles.
Thanks for this article, Willis. I’m getting to like your work more these days.
If Darwin understood this, how come the parasites at Browndeath, sorry, Greenpeace don’t understand it? And they call us flat earthers!
Here in the UK we have taken to building houses on flood plains. It’s cheaper because the land is already pretty level and easier to excavate. It counts for nothing that this is the best agricultural land; ‘why do we have to grow food when we can just buy it (so last century).’ But when the floods come it always seems to be someone else’s fault, or global warming. But then everyone needs to be a victim of something so that someone else can be made to pay. This is their thermosocialist paradise. Seems to have similarities to what you are saying.
So the third claim is not true either. Atolls are created by sea level rise, not destroyed by sea level rise.
Don’t the greenies get pretty well everything back to front?
What an excellent post!
Well reasoned, researched and presented
Great job
More nonsense on sea levels http://bushynews.com/?p=10
Re: Patrick Davis (01:04:34) :
At a 7% increase per year the consumption roughly doubles every decade (actually its by 1.97 but its close enough). What this means is if you use 1 unit in the first decade then you will use 2 units the next decade and 4 the one after etc. In other words your usage in any one decade is the sum of your usage in all previous decades (1+2+4+etc) plus one.
At some point in the future we will have used 50% of the fossil fuel resources (whether this is in 10, 20 or 100 years) and if the consumption is still increasing at 7% then there will only be a decades worth of fossil fuel left. This is a mathematical certainty and is due to the doubling every decade.
” When you think about it though, a Coral Atoll is almost the only piece of land that doesn’t have a problem with sea levels, given the coral will always grow right up to the bottom of the low tide level.”
Not quite true in the long run. Sooner or later the corals always lose out to sea-level rise. There are no really old atolls, geologically speaking. As the volcanic islands move away from the spreading ridges and hotspots where they are created yhe seabottom they stand on gradually subsides and the “high” islands become “low” and ultimately change to atolls which for a while keep up with subsidence but finally become submarine reefs and ultimately seamounts (a. k. a. guyots). The whole process takes several million years, and is beautifully illustrated by the Hawaii island chain, from Big Island (active volcanoes) through the “high” islands getting ever lower to the west and turning into atolls, and ultimately to seamounts west of Midway. Also there is a new island building SE of Big Island (Loihi seamount) which is now less than 1000 meters below sea level and will very likely “surface” within a few thousand years.
Of course ytectonics occasionally goes the other way too. There are several “high” ex-atolls where the former lagoon is now a dry limestone plateau. Niue and Henderson Island are examples of this.
Incidentally here is an interesting paper with regard to the “Maldives disappearing act”:
Late Quaternary reef growth and sea level in the Maldives (Indian Ocean)
GISCHLER Eberhard ; HUDSON J. Harold ; PISERA Andrzej ;
Marine geology, vol. 250(1-2):104-113.
Abstract
Based on rotary drilling and radiometric and U-series dating, we present the first comprehensive data on Holocene reef anatomy and sea-level rise as well as nature and age of underlying Pleistocene limestone in the Maldives. Holocene reefs in Rasdhoo Atoll, central Maldives, are composed of four facies including (1) robust-branching coral facies, (2) coralline algal facies, (3) domal coral facies, and (4) detrital sand and rubble facies. Branching coral and coralline algal facies predominate the marginal reefs and domal corals and detrital facies preferentially occur in a lagoon reef. In addition, microbialite crusts are found in lower core sections of marginal reefs. Microbialites formed during the early Holocene in reef cavities. Holocene reef thickness ranges from 14.5 m to >22 m. Reef growth started as early as 8.5 kyr BP. Marginal reefs accreted in the keep-up mode with rates of > 15 m/kyr. Rate of sea-level rise significantly slowed down from 7-6 kyr BP and subsequently gradually rose with rates < 1 m/kyr. The lagoon reef accreted in the catch-up mode with rates of around 4 m/kyr. Even though no indications of a higher than present sea level were found during this study, it is not entirely clear from the data whether the sea gradually rose to or exceeded present level in the late Holocene. Submarine cementation in Holocene reefs studied is rather weak, presumably as a consequence of high accretion-rates, i.e., short time available for consolidation. Pleistocene coral grainstone was encountered in one core at 14.5 m below present level and three U-series dates indicate deposition during marine isotope stage 5e ca. 135 kyr BP.
So 14.5-22 meters (45-70 feet) of coral has accumulated in about 10,000 years, and the reef (if left in peace) is capable of keeping up with a sea-level rise of more than 15 mm/yr, i. e. five times the current rate, or equivalent to at least 1.35 meters (4.5 feet) to 2100.
From The Times:
http://www.timesonline.co.uk/tol/news/environment/article7004936.ece
Brilliant, an excellent resource. When I read of dynamiting and dredging of reefs and then they seek reparation from us for “climate change damage caused by our use of fossil fuels” it makes me spit.
And they are now employing greenie advisors to tell them how to get the money, Greenpeace are advising Tuvalu:
http://www.worldwatch.org/node/6360
Q. “How did you, an Australian native, become Tuvalu’s lead climate negotiator?
A. I’ve been on the job for 11 years. I was working for Earth Negotiations Bulletin and Greenpeace before that.
I met the prime minister of Tuvalu at a meeting and provided him with a briefing on climate change. He then invited me to come onto their delegation at [the 1997 climate negotiations in Kyoto, Japan]. It evolved from there. I now work full time for the Tuvalu government as an international environment advisor. ”
The other moonbat journo, Mark Lynas, is now climate advisor to the Maldives government,
http://www.climatevulnerableforum.gov.mv/?page_id=52
Speech for the Climate Vulnerable Forum – Mark Lynas, Climate Adviser to the Maldives:
“We are here today because we know what climate change means. For us, this is not a scientific abstraction.”
“Here in the Maldives, the very integrity of the nation is being eroded, by a triple-whammy: rising ocean levels which swamp the islands, higher sea surface temperatures which kill the coral, and ocean acidification which dissolves the carbonate rocks the reefs are built from.”
Money, money, money, always money…..
I have done a great deal of diving round the great barrier reef in Northern Queensland.
One thing I have noticed is that damage to coral reefs in this area gets worse the closer you are to mainland Australia. The close in reefs are in fairly poor condition. The dive sites a little further out really arent in bad condition and the reefs like Osprey which are up to 200km off the mainland I would describe as pretty much pristine and I have plenty of video footage to back this up.
I’m not a scientist but this raises some questions for me and makes me think that most of the reef damage closer in is probably related to agricultural run off and to some extent tourism (large amounts of inexperienced divers and boat traffic can play havoc with a reef).
I’d really like to see some studies of remote reefs to see if they show the same degree of susceptibility to alleged warming SST’s as the sites close to the mainland. My experience from hundreds of dives on these sites is they do not.
Even the BBC is now publishing stuff that says “it could still be big trouble (read we have grants that have to be protected with caveats), but it may not be as bad as we predicted:
http://news.bbc.co.uk/1/hi/sci/tech/8483722.stm
Clive – Please explain to me how to save this as a pdf file. Thanks in anticipation.
Many thanks, an excellent piece on an important subject.It’s ironic that the islands were created in the first place by sea level rise!
Chris
“TerryS (03:32:44) :
At some point in the future we will have used 50% of the fossil fuel resources (whether this is in 10, 20 or 100 years) and if the consumption is still increasing at 7% then there will only be a decades worth of fossil fuel left. This is a mathematical certainty and is due to the doubling every decade.”
Only true if no new discoveries are made, the “prediction” It is based on current reserves. As ~70% of the Earth is undicovered…well, who says what is finite (In human terms)? Oil companies (Just drooling for liquid CO2, thanks to our taxes).
@ur momisugly TerryS (03:32:44) :
thanks for explaining
“Despite never being more than a few metres tall, hey have survived a sea level rise of up to three hundred plus feet …”
The “t” that goes with the “hey” must have evaporated… too much sunlight… [:o]
Very interesting article. I had no idea that atolls were so cool. Almost like a well made drink with multiple layers… [:)]
Actually, the doubling every decade at 7% increase is something that many sceptics gloss over when stating that we add 3% of CO2 (of the 0.038%) to the atmosphere annually. #%, that’s not much is it? Well, by the same principle, that doubles the CO2 we have contributed every 23 years.
Having said that, it is reassuring that the CO2 concentrations only seem to be increasing in a linear fashion, so the plants of the world are probably feasting well.
TerryS (03:32:44) :
This is a mathematical certainty and is due to the doubling every decade.
What is not a certainty is the doubling every decade; just a projected trend.
JER0ME (00:51:23) :
This seriously call for a really hard look at some kind of resource that is not finite.
Sounds like you should try theology for that. This is the real world. But I shouldn’t worry about the trends. They don’t continue.
Patrick Davis (04:10:29) :
This is, as TerryS sates, a mathematical certainty. The only ambiguity is what constitutes ‘50%’. The lecture points out very clearly that when estimated (by experts) reserves are taken into account, we will probably have 30 to 40 years left tops if we increase consumption at 7%. The trouble is, as the man states very clearly (and I think is demonstrated here, possibly) we do not immediately understand the impact of a 7% increase of something, or ‘exponential growth’ think ‘compound interest’. At a 7% interest rate, your money doubles every 10 years. At a 7% annual increase in consumption, you double the amount consumed every 10 years.
So when we have used 50% of all fuels (and that is never certain until we know there is no more), if we carry on increasing our rate of consumption, we have only 10 more years of consumption left. It’s as simple as that.
The lesson I take home is a finite resource with increasing consumption (and that may even be ‘steady’ per capita consumption), will cause a far more rapid end pint than common sense tells us. Decades of increasing consumption teaches us there are decades more. Mathematics dictates different. The end is a swift one, and in this case painful. So we need to invest in a resource that is not finite. That would be renewable energy, although Fusion could give us a lot of breathing space.
‘Nuff said, I won’t bang on about it, but it is a bit of a revelation to me, although obvious to the mathematician in me now.