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May 10, 2009

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Things change. People adapt. I have uprooted my family several times in my adult life. My parents did the same when I was a child. My ancestors migrated from europe to america, from a place where civil wars occurred to a place where civil war would occur.

There have been human migrations all over the globe throughout history - many for climate reasons resulting from ice ages and droughts. The ocean has been rising for thousands of years.

Nonetheless, it is unfortunate that the people on this island have to relocate. It is also unfortunate that their migration will be used as a cudgel on the rest of us to suit someone's political purposes.

Things change. People adapt.

[...]

Nonetheless, it is unfortunate that the people on this island have to relocate. It is also unfortunate that their migration will be used as a cudgel on the rest of us to suit someone's political purposes.

I note that d'd'd'dave's comment here could, with exactly the same degree of responsiveness, be posted in response to a post about the Holocaust, the Armenian genocide, the population exchanges of India and Pakistan at independence, the eruption of Mount Vesuvius, Stalin's movement of Soviet populations, the Nakba, the Black Plague, civil wars, whatever.

Hey, stuff happens. It's unfortunate. It is also unfortunate if someone discusses such events to suit "political purposes."

These things happen, you know.

But if marginal tax rates go up three percent, it's time for revolution!

Priorities, people!

the Holocaust, the Armenian genocide, the population exchanges of India and Pakistan at independence, Stalin's movement of Soviet populations, the Nakba, civil wars, increase in marginal tax rates: All caused by politics. All suitable to discuss for political purposes.

the eruption of Mount Vesuvius, the Black Plague, rising seas: all natural occurrences, not susceptible to political solutions. Attempts to politicize them are unfortunate.

But you knew that didn't you Mr Farber.

From wikipedia:

"Oral tradition states that the Carteret Islands were originally inhabited by a Polynesian group closely related to the Nukumanu, or Mortlock Islanders. The islands were discovered by a fishing expedition from Hahalis. According to the Halia tradition, the first attempt to reach the islands had a peaceful intention, but ended in the massacre of the Halia expedition. The Munihil, or paramount chief of Hanahan Bay then organized a large flotilla of canoes to attack the Polynesian population, and conquered the islands. By contrast, the Mortlock Islanders state that the Halia mounted a blood and murder surprise attack to remove their relatives.
Genealogical information suggest that the Halia invasion would have taken place in the early 18th century."

It doesn't matter how they got possession of the Carterets. It doesn't matter that they arrived on the Carterets only 250 years ago. All that matters is that they have to leave now.

D'd'd'dave, what is your point? I mean, I pretty much agree with your last sentence, but if you really feel that way why write the comment at all?

I mean, if you can find any Carteret Islanders who participated in an expansionist massacre, I'm all in favor of leaving them to wither on the drowning island they seized. But I should wish ill upon their fairly distant descendants, people who never met anyone who ever met any of them, why exactly?

"the eruption of Mount Vesuvius, the Black Plague, rising seas: all natural occurrences, not susceptible to political solutions."

No, d'd'd'dave.

If someone had good reason to predict the eruption of a volcano -- say, a good volcano eruption warning system, political discussion of whether to fund that system, or not to, or whether or not to carry out an eruption in advance, would be warranted.

If someone funded a health care system, or didn't, that could help save innumerable lives from the Black Death, or influenza, or another disease or health problem, political discussion of whether to fund it, or at what level to fund it, or how to implement it, would be warranted.

If rising seas were influenced by man-made events and behaviors and decisions, and there were means to change some of those events, or behaviors, or decisions, or decisions to be made as to how to save people's lives, or ameliorate the destruction or harm in their lives, of rising seas, political discussion of these decisions would be entirely warranted.

In all these cases, political discussion would be entirely warranted.

But if it's a political discussion you don't like, then it's a "political cudgel," and such things shouldn't be spoken of.

Argue any position you like about global warming, or what should or shouldn't be done about it: up to you. But claiming that somehow there's nothing to be done about it, and there should be no discussion about it, is a political discussion, and your assertion is as much a "political cudgel" as any other political opinion. Your political purposes are as political as any other political purposes.

But you knew that, didn't you?

I was going to assume lots of folks here have already read this, but then it occurred to me that, of course, some folks wouldn't have.

It seems relevant.

d'd'd'dave says:
"the eruption of Mount Vesuvius, the Black Plague, rising seas: all natural occurrences, not susceptible to political solutions."

Vesuvius: the polity in the vicinity of a volcano cannot (at present) prevent an eruption, true. But they can choose to spend resources learning about volcanic activity and monitoring the volcano, pass building ordinances and restrictions within a certain proximity of the danger zones, etc. These are all political actions that must be paid for, or limit individuals freedoms, but are made with the intent to save lives and property.

The Black Plague: New diseases and strains arise, true. Communities can choose to spend resources learning about infectious diseases, treatments, vaccines, preventative behaviors, etc. The decision to fund such research is a political action requiring the raising and appropriation of revenue. The decision to fund (or not fund) medical treatment for the general population is a political decision.

Rising seas: sea levels may rise because of different, or a combination of reasons. There may be climate changes beyond human control, but some factors contributing to climate change are under human control. Learning as much as possible about these mechanisms requires resources, taking action on those factors within human control requires political decisions, and deciding what happens to the people affected by climate change requires political decisions. Do we let the islanders starve or drown? Do we pay for their relocation? On whose land are they relocated?

Threats to the well-being of the community at large require the community to decide how to address them. While it is certainly possible to come to the conclusion that we are too ignorant and impotent to do anything, it seems to me that at a minimum doing what we can to reduce our ignorance and increase our potency is worthwhile. How much effort the community dedicates to those tasks is ultimately a political decision.

It is a joy to read Gary F. lancing d'd'd'dave's boil, but we knew that, didn't we.

Not to forget that the spread of the Black Death had a lot to do with politics/ies. It was carried (unknowingly) to the West by an army and then used (deliberately) as a weapon (catapulting plague vitims into a beleagured city) and then spread by sailors to Italy where failed quarantine measures allowed them to infect a whole chain of cities.
As for climate change, it's not just coasts receding but also deserts expanding. In some countries both happen together, reducing the usable land from two directions. 'Just move inland' is therefore not necessarily an option even on large land masses.

"But that would not show that global warming did not also contribute to what's happening:"

No, that would be the responsibility of the sea level gauges. Which indicate that any contribution is de minimus.

It's a volcanic region, islands actually DO go up and down for reasons utterly unrelated to tiny changes in atmospheric temperatures.

Brett, 30cm in ten years for a low-lying island is 'de minimus'? Really?

...that would be 30 mm. Global mean sea level rise is 3.2mm/year, plus or minus about a half. Call it an inch and a half per decade, max.

Brett, there are more sophisticated devices measuring sea level than sea level gauges.

Sea level is in fact on the rise, globally. Subsidence complicates the picture posed by sea level rise, but the two are in fact separate things. I don't know what the dominant effect is in the Carterets, and I can't find that anyone else knows, either.

No, that would be the responsibility of the sea level gauges. Which indicate that any contribution is de minimus.

Link, please?

I would also love it if someone found sea level gauge readings in the vicinity -- I looked for them last night, to no avail.

That said: the article cited in the post says that they rose "almost an inch (2.5 centimeters) every year in parts of the western Pacific and Indian oceans." Over ten years, that would be almost ten inches. That's not de minimis at all.

Sea level gauges only show the rise (or fall) of sea level relative to land, which is why they're fairly useless for places that are subsiding, such as New Orleans, parts of which are subsiding at nearly 10x the global mean sea level rise.

Again: no idea to what extent this is true for the Carterets.

"all natural occurrences, not susceptible to political solutions."

Increases of ambient CO2 due to industrial culture: susceptible to political solution.

Well, what are radar satellites for? They can measure the Earth crust go up and down with the tides. Therefore, they should be able to tell whether those islands are going down in absolute numbers, not just in comparision to sea levels, or not.
Apart from that, increased frequency of extreme weather events also plays a part in whether an island is still inhabitable or not.

Well, what are radar satellites for? They can measure the Earth crust go up and down with the tides. Therefore, they should be able to tell whether those islands are going down in absolute numbers, not just in comparision to sea levels, or not.

Yes, they should be able to do that. The question is, has anyone taken the trouble to make that happen?

I'd imagine the data would be both out there and summarized in Wikipedia by now, if it existed. New Orleans data is here, if anyone's interested.

There's also the GRACE satellites, which measure very small changes in gravitational forces. I believe it was primarily them that pointed out how much ice Antarctica is losing over time. They've also been used to measure how the oceans aren't really level, which is how the levels in one region can go up more than in another.

They've also been used to measure how the oceans aren't really level

What do you mean by "aren't really level"? For this to be true, there has to be some force other than gravity acting on them.

The definition of "level" needs some agreement. Level relative to the local field (which is the actual, localized vertical deflection), level relative to some reference geoid, and level relative to some reference ellipsoid are all different, in general. The actual gravity field of the earth has got wrinkles in it, although they're too subtle for the effects to be sensed by humans.

I know something about this, so let me offer the following:

1. Rising water level comes from (a) melting of ice on land [sea ice doesn't matter] and (b) the upper waters of the ocean getting warmer (they expand). (a) contributes the same everywhere, (b) can be, over a few years, different from place to place. There are also a lot of year-to-decade fluctuations, especially near continental coasts. These fluctuations make it hard to get a good number from tide gauges, which is why radar satellites, which can average over the whole ocean, are useful. They cannot measure what the land is doing, since the radar returns are good only over the ocean.

2. The overall rate is about 3 mm/yr, which is higher than the long-term average (since about 1850, when records start).

3. Local sea level change is water level rise combined with land motion--one example is that sea level rise in the Chesapeake Bay is more rapid than global numbers because the land is still sinking back to equilibrium, after having been uplifted because of the loading by glaciers to the north, during the Ice Age. The Carterets are on the edge of a very tectonically active area, so they might well have their own local motion.

4. None of which is to say that sea level rise from global warming might not be a hugely expensive problem--much melting in the major ice caps, and we will all be very unhappy.

As far as natural vs political, what everyone else said.

one example is that sea level rise in the Chesapeake Bay is more rapid than global numbers because the land is still sinking back to equilibrium, after having been uplifted because of the loading by glaciers to the north, during the Ice Age

I think the there's another theory for the rapid rise:

[snip]Suddenly, with an intense flash of light, that tranquil scene was transformed into a hellish cauldron of mass destruction. From the far reaches of space, a bolide (comet or asteroid), 3-5 kilometers in diameter, swooped through the Earth's atmosphere and blasted an enormous crater into the continental shelf. The crater is now approximately 200 km southeast of Washington, D.C., and is buried 300-500 meters beneath the southern part of Chesapeake Bay and the peninsulas of southeastern Virginia (fig. 1).[snip]

[snip]The Chesapeake Bay crater was recently identified by C. Wylie Poag (U.S. Geological Survey, USGS), who has assembled an international team to investigate its characteristics and consequences. Evidence of the crater comes from two sources: (1) cores drilled by the USGS and the Virginia State Water Control Board (fig. 2), and (2) marine seismic-reflection profiles collected by Texaco, Inc., the USGS, and the National Geographic Society[snip]

[snip]Evidence of accelerated land subsidence is reflected in the geology and topography of the modern land surfaces around the crater. The breccia is 1.3 km thick and was deposited as a water-saturated, sandy, rubble-bearing slurry (like concrete before it hardens). The sediment layers surrounding the crater, on the other hand, were already partly consolidated, and so the mushy breccia compacted much more rapidly under its subsequent sediment load than the surrounding strata. The compaction differences produced a subsidence differential, causing the land surface over the breccia to remain lower than the land surface over sediments outside the crater.[snip]

I think that's cool, anyway.

"If someone had good reason to predict the eruption of a volcano -- say, a good volcano eruption warning system, political discussion of whether to fund that system, or not to, or whether or not to carry out an eruption in advance, would be warranted."

Sheesh: this should be "If someone had good reason to predict the eruption of a volcano -- say, a good volcano eruption warning system -- political discussion of whether to fund that system, or not to, or whether or not to carry out an evacuation in advance would be warranted."

Carry out an eruption in advance? Sounds like a bad idea.

"[snip]Suddenly, with an intense flash of light, that tranquil scene was transformed into a hellish cauldron of mass destruction. From the far reaches of space, a bolide (comet or asteroid), 3-5 kilometers in diameter, swooped through the Earth's atmosphere and blasted an enormous crater into the continental shelf."

Continuing:

[...] Then came the night of the first falling star. It was seen early in the morning, rushing over Winchester eastward, a line of flame high in the atmosphere. Hundreds must have seen it, and taken it for an ordinary falling star. Albin described it as leaving a greenish streak behind it that glowed for some seconds. Denning, our greatest authority on meteorites, stated that the height of its first appearance was about ninety or one hundred miles. It seemed to him that it fell to earth about one hundred miles east of him.

[...]

The Thing itself lay almost entirely buried in sand, amidst the scattered splinters of a fir tree it had shivered to fragments in its descent. The uncovered part had the appearance of a huge cylinder, caked over and its outline softened by a thick scaly dun-coloured incrustation. It had a diameter of about thirty yards. He approached the mass, surprised at the size and more so at the shape, since most meteorites are rounded more or less completely. It was, however, still so hot from its flight through the air as to forbid his near approach. A stirring noise within its cylinder he ascribed to the unequal cooling of its surface; for at that time it had not occurred to him that it might be hollow.

Surely modern survey equipment accounts for and therefore eliminates the impact of geologic subsidence from sea level measurements, even on remote islands. That argument is a non-starter.

"What do you mean by "aren't really level"? For this to be true, there has to be some force other than gravity acting on them."

Yes, there are other forces at work besides gravity shaping the details of the ocean surface topography, at a scale of a couple of meters or less. For example coriolis effects and the way that they interact with the shape of the oceans create topographic highs or "bulges" in the center of several of the largest ocean basins where mean sea level is higher than it would be in the absence of those forces, with corresponding topographic lows distributed elsewhere.

These and other ocean current and tidal effects are why for example mean sea level on the Atlantic and Pacific sides of the Panama Canal differ by several inches. Theoretically we could dig a deeper canal (i.e. one that doesn't use locks to climb the land in between) and generate energy by letting the water slosh thru from one side to the other. IIRC the Pacific is slightly higher than the Atlantic, so the net flow would be from west to east, but variable effects would in practice create bidirectional flows at different times. This would have undesirable effects biologically, and I have no idea if it is close to being economically feasible, but on a purely theoretical level it is sort of a cool idea.

/oceanography nerd

Thanks, TLTIABG. I rather thought there might be some lingering current-generated effects, like you see in streams.

Surely modern survey equipment accounts for and therefore eliminates the impact of geologic subsidence from sea level measurements, even on remote islands.

You have a cite, I imagine. Please share. Not that such equipment exists, that it's omnipresent.

That argument is a non-starter.

Not without a cite, it's not.

As a random example, Trimble R8 has a static vertical accuracy of +/-5mm, and that's just one technology that can be brought to bear.

That's cool. Those have been around for a while; you'd think that folks would be using them and reporting results. Maybe the price tag is a deterrent, or the fact that you've got to have someone on site to take the data. You could probably come up with an always-on remote sensing station based on one of these, but I'm guessing that would push the cost way up over $10k (or more; $7k is the price tag for just the R8).

With that kind of accuracy, there's all kinds of things that have to be done to the data to make it sensible. Removal of solid-earth tides, for instance.

Err...Earth tides.

Typepad's arbitrary removal and restoration of text formatting, including links, is driving me crazy.

There seems to be a concerted global effort in place to track vertical movement of tidal gauges, both in real time and historically. I found a few links:

http://www.pol.ac.uk/psmsl/landmove.html

http://ilikai.soest.hawaii.edu/uhslc/data.html

Including a database of gauges with GPS monitors:

http://www.sonel.org/spip.php?page=cgps

As LeftTurn said above, there is both global sea level rise, caused by the change in the volume of the oceans, and local regional changes, due to the distribution of water changing. Things like changes in ocean currents, would have regional effects. A change in the earths rotational axis -or rate of rotation, (predicted to happen by changes in ice sheets) also can move water from one ocean basin to another. Often an extinct volcano would be expected to be subsiding, as the cooling of the rock underneath makes it contract in volume. If the stated number of 2.5cm/year is taken at face value, than only about 1 part in eight of this problem seems to be attributable to climate change (perhaps more or less, if climate change is altering the distribution of ocean water).

More than bing directly to blame for the plight of these islanders, we should think of their predicament more as a warning of something that will become increasingly common because of global warming.

"More than bing directly to blame for the plight of these islanders, we should think of their predicament more as a warning of something that will become increasingly common because of global warming."

That canary in the coal mine, it was just getting old, or ate some bad birdseed. Useless bird, I never liked it anyway. Keep those shovels digging boys!

Carry out an eruption in advance? Sounds like a bad idea.
Not necessarily. If it is possible to control the direction, it might be the right answer in some cases (I think it is even practiced occasionally). Also in some cases a triggered earlier eruption may be less violent than one allowed to build up for too long (although I am aware that 'pressure release' can be the worst possible thing in other cases).

"Carry out an eruption in advance?"

I think they have medication to address that now.

If you check your email, there are probably 42,789 messages about it.

:)

"I think they have medication to address that now."

Side effects may include pahoehoe, a'a, lahars and nuées ardentes. If you experience an eruption lasting longer than 3 hours, please see a geologist.

Sorry I stirred the pot with my uneven ocean comment and then left. Here's a good link to describe it:
http://nasadaacs.eos.nasa.gov/articles/2005/2005_gravity.html.

I recalled that the unevenness was much larger than I would have expected. The link mentions several hundred feet difference, based on the geoid.

The points of maximum geoid deviation from the ellipsoid are about -106 m (near south of India) and +84m (somewhere in Papua New Guinea). So, yes, the vertical distance between the reference ellipsoid (which, it should be noted, doesn't actually exist; it's a surface of convenience) these points is over 600 feet.

These deviations would occur without any ocean currents at all, because they're variations in the local gravity field. The surface of constant acceleration of gravity is, as I said, rather more wrinkly than one would expect if one wasn't in the business of knowing these things.

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