William Gilbert Exemplary Scientist from 400+ Years Ago

Good Science by William Gilbert 1544 to 1603

English physician, physicist, natural philosopher and author of De Magnete (On the Magnet and Magnetic Bodies) and of “On the Great Magnet the Earth.”

Wonderful account of scientific thinking and experiments from the distant past.

Among his conclusions were that the Earth's core was made of iron. And he correctly observed and identified as important that when magnets are cut in two, each forms a new magnet with north and south poles. In physics we say that magnetic monopoles do not exist (under earthly conditions.)  An exception might be during the very early stages of the big bang. But I digress.

...but back to Dr. Gilbert in the year 1600.

A few impressive bits from the quotation below....

Notice Gilbert clearly describes the distinction between the magnetic north pole and the geodetic or geographic north pole. This is called the “variation of the location,” that is, the difference in direction between true north and magnetic north. A “must know” for navigation by magnetic compass.

An iron bar suspended from a cross-woven silk cord becomes an elegant experiment under Gilbert.

QUOTATION from Chapter 12 Book 1 of De Magnete (with a little editing)

A long piece of Iron, even though not excited by a loadstone, settles itself toward North and South.

Every good and perfect piece of iron, if drawn out in length, points North and South, just as the loadstone or iron rubbed with a magnetical body does; a thing that our famous philosophers have little understood, who have sweated in vain to set forth the magnetick virtues and the causes of the friendship of iron for the stone.

You may experiment with either large or small iron works, and either in air or in water. A straight piece of iron six feet long of the thickness of your finger is suspended (in the way described in the foregoing chapter) in exact equipoise by a strong and slender silken cord.

But the cord should be cross-woven of several silk filaments, not twisted simply in one way; and it should be in a small chamber with all doors and windows closed, that the wind may not enter, nor the air of the room be in any way disturbed.

For which reason it is not expedient that the trial should be made on windy days, or while a storm is brewing.

For thus it freely follows its bent, and slowly moves until at length, as it rests, it points with its ends North and South, just as iron touched with a loadstone does in shadow-clocks, and in compasses, and in the mariners' compass. You will be able, if curious enough, to balance all at the same time by fine threads a number of small rods, or iron wires, or long pins with which women knit stockings; you will see that all of them at the same time are in accord, unless there be some error in this delicate operation: for unless you prepare everything fitly and skilfully, the labor will be void.

Make trial of this thing in water also, which is done both more certainly and more easily. Let an iron wire two or three digits long, more or less, be passed through a round cork, so that it may just float upon water; and as soon as you have committed it to the waves, it turns upon its own center, and one end tends to the North, the other to the South; the causes of which you will afterwards find in the laws of the direction.

This too you should understand, and hold firmly in memory, that as a strong loadstone, and iron touched with the same, do not invariably point exactly to the true pole but to the point of the variation. So does a weaker loadstone, and so does the iron, which directs itself by its own forces only, not by those impressed by the stone.

And so every ore of iron, and all bodies naturally endowed with something of the iron nature, and prepared, turn to the same point of the horizon, according to the place of the variation in that particular region (if there be any variation therein), and there abide and rest.

-William Gilbert De Magnete published in 1600!

Good Science | Real Data | Earth's Climate Change Cycles | Over Past Million Years

Good Science Looks Bad for Theory of Human-Vehicle-Caused Global Warming: A collection of articles, data, and additional commentary on continuous cycles of climate change.

Draft Version: January 2011

Given that climate science is often invoked in political policy setting deliberations, we as scientists are obliged to make the science understandable to the citizenry who, through their representatives, have ultimate policy setting responsibility.


We are further obliged as scientists, to identify, correct, or discard unsound scientific methods, models, and theories.

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OUTLINE OF CONTENTS

Update:  Lake Vostok Project January 2011

Part 1: A great "Scientific American" level article by G.F. Fegel. Published in English Pravda.

Fig. 1     420,000 Year History of Climate Cycles from Vostok Ice Core Data.

Part 2: Explanation and interpretation of data in Fig. 1, and natural cycles of climate change.

Part 3: Natural regulation of atmospheric CO2 by oceans, lakes, streams and their inhabitants.

Intermission: Thought Experiment.  What happens if we could....?

Fig. 2    5,300,000 Year History of Climate Cycles from Ocean Floor Sediment Data.

Part 4: A five million year record of Earth's climate cycles, Fig. 2, discussion and interpretation.

Part 5: Wikipedia article as an example of sloppy thinking and bad science found frequently in the climate   literature promoted by agenda driven believers.


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Lake Vostok in the news January 2011


Since 1990, the Arctic and Antarctic Research Institute in St. Petersberg, Russia has been drilling through the ice to reach lake Vostok. Now scientists in the field, near the south pole are poised to finally reach the deep sub-glacial lake after more than 20 years of effort. Lake Vostok is expected to be home for exotic lifeforms adapted to it's unique super-oxygenated water environment.  Interestingly, the conditions in Lake Vostok are believed to be similar to the conditions on Jupiter's moon Europa and Saturn's Enceladus. Vostok research may support hopes for finding ET-life in sub-glacial lakes elsewhere in our solar system. 


Article in Wired Magazine and map location of Lake Vostok: 
http://www.wired.co.uk/news/archive/2011-01/07/russians-penetrate-lake-vostok



I would like to offer my personal heartfelt congratulations to the brave and dedicated Vostok Research Team for achieving this truly remarkable scientific and technical feat in the face of arduous conditions on the glaciers of Antarctica. 


S.C. Luckhardt, Ph.D.
Palm Springs CA
January 7, 2011

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GLOBAL ICE AGE PREDICTED BY CLIMATE SCIENTISTS

Pravda January 2009

http://english.pravda.ru/science/earth/106922-0/

By Gregory F. Fegel

Page 1

The earth is now on the brink of entering another Ice Age, according to a large and compelling body of evidence from within the field of climate science. Many sources of data which provide our knowledge base of long-term climate change indicate that the warm, twelve thousand year-long Holocene period will rather soon be coming to an end, and then the earth will return to Ice Age conditions for the next 100,000 years.

Ice cores, ocean sediment cores, the geologic record, and studies of ancient plant and animal populations all demonstrate a regular cyclic pattern of Ice Age glacial maximums which each last about 100,000 years, separated by intervening warm interglacials, each lasting about 12,000 years.

Most of the long-term climate data collected from various sources also shows a strong correlation with the three astronomical cycles which are together known as the Milankovich cycles. The three Milankovich cycles include the tilt of the earth, which varies over a 41,000 year period; the shape of the earth’s orbit, which changes over a period of 100,000 years; and the Precession of the Equinoxes, also known as the earth’s ‘wobble’, which gradually rotates the direction of the earth’s axis over a period of 26,000 years. According to the Milankovich theory of Ice Age causation, these three astronomical cycles, each of which effects the amount of solar radiation which reaches the earth, act together to produce the cycle of cold Ice Age maximums and warm interglacials.

Elements of the astronomical theory of Ice Age causation were first presented by the French mathematician Joseph Adhemar in 1842, it was developed further by the English prodigy Joseph Croll in 1875, and the theory was established in its present form by the Czech mathematician Milutin Milankovich in the 1920s and 30s. In 1976 the prestigious journal “Science” published a landmark paper by John Imbrie, James Hays, and Nicholas Shackleton entitled “Variations in the Earth's orbit: Pacemaker of the Ice Ages,” which described the correlation which the trio of scientist/authors had found between the climate data obtained from ocean sediment cores and the patterns of the astronomical Milankovich cycles. Since the late 1970s, the Milankovich theory has remained the predominant theory to account for Ice Age causation among climate scientists, and hence the Milankovich theory is always described in textbooks of climatology and in encyclopedia articles about the Ice Ages.

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Page 2

In their 1976 paper Imbrie, Hays, and Shackleton wrote that their own climate forecasts, which were based on sea-sediment cores and the Milankovich cycles, "… must be qualified in two ways. First, they apply only to the natural component of future climatic trends - and not to anthropogenic effects such as those due to the burning of fossil fuels. Second, they describe only the long-term trends, because they are linked to orbital variations with periods of 20,000 years and longer. Climatic oscillations at higher frequencies are not predicted... the results indicate that the long-term trend over the next 20,000 years is towards extensive Northern Hemisphere glaciation and cooler climate."

During the 1970s the famous American astronomer Carl Sagan and other scientists began promoting the theory that ‘greenhouse gasses’ such as carbon dioxide, or CO2, produced by human industries could lead to catastrophic global warming. Since the 1970s the theory of ‘anthropogenic global warming’ (AGW) has gradually become accepted as fact by most of the academic establishment, and their acceptance of AGW has inspired a global movement to encourage governments to make pivotal changes to prevent the worsening of AGW.

The central piece of evidence that is cited in support of the AGW theory is the famous ‘hockey stick’ graph which was presented by Al Gore in his 2006 film “An Inconvenient Truth.” The ‘hockey stick’ graph shows an acute upward spike in global temperatures which began during the 1970s and continued through the winter of 2006/07. However, this warming trend was interrupted when the winter of 2007/8 delivered the deepest snow cover to the Northern Hemisphere since 1966 and the coldest temperatures since 2001. It now appears that the current Northern Hemisphere winter of 2008/09 will probably equal or surpass the winter of 2007/08 for both snow depth and cold temperatures.

The main flaw in the AGW theory is that its proponents focus on evidence from only the past one thousand years at most, while ignoring the evidence from the past million years -- evidence which is essential for a true understanding of climatology. The data from paleoclimatology provides us with an alternative and more credible explanation for the recent global temperature spike, based on the natural cycle of Ice Age maximums and interglacials.

In 1999 the British journal “Nature” published the results of data derived from glacial ice cores collected at the Russia ’s Vostok station in Antarctica during the 1990s. The Vostok ice core data includes a record of global atmospheric temperatures, atmospheric CO2 and other greenhouse gases, and airborne particulates starting from 420,000 years ago and continuing through history up to our present time.

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Page 3

The graph of the Vostok ice core data shows that the Ice Age maximums and the warm interglacials occur within a regular cyclic pattern, the graph-line of which is similar to the rhythm of a heartbeat on an electrocardiogram tracing. The Vostok data graph also shows that changes in global CO2 levels lag behind global temperature changes by about eight hundred years. What that indicates is that global temperatures precede or cause global CO2 changes, and not the reverse. In other words, increasing atmospheric CO2 is not causing global temperature to rise; instead the natural cyclic increase in global temperature is causing global CO2 to rise.

The reason that global CO2 levels rise and fall in response to the global temperature is because cold water is capable of retaining more CO2 than warm water. That is why carbonated beverages loose their carbonation, or CO2, when stored in a warm environment. We store our carbonated soft drinks, wine, and beer in a cool place to prevent them from loosing their ‘fizz’, which is a feature of their carbonation, or CO2 content. The earth is currently warming as a result of the natural Ice Age cycle, and as the oceans get warmer, they release increasing amounts of CO2 into the atmosphere.

Because the release of CO2 by the warming oceans lags behind the changes in the earth’s temperature, we should expect to see global CO2 levels continue to rise for another eight hundred years after the end of the earth’s current Interglacial warm period. We should already be eight hundred years into the coming Ice Age before global CO2 levels begin to drop in response to the increased chilling of the world’s oceans.

The Vostok ice core data graph reveals that global CO2 levels regularly rose and fell in a direct response to the natural cycle of Ice Age minimums and maximums during the past four hundred and twenty thousand years. Within that natural cycle, about every 110,000 years global temperatures, followed by global CO2 levels, have peaked at approximately the same levels which they are at today.

About 325,000 years ago, at the peak of a warm interglacial, global temperature and CO2 levels were higher than they are today. Today we are again at the peak, and near to the end, of a warm interglacial, and the earth is now due to enter the next Ice Age. If we are lucky, we may have a few years to prepare for it. The Ice Age will return, as it always has, in its regular and natural cycle, with or without any influence from the effects of AGW.

The AGW theory is based on data that is drawn from a ridiculously narrow span of time and it demonstrates a wanton disregard for the ‘big picture’ of long-term climate change. The data from paleoclimatology, including ice cores, sea sediments, geology, paleobotany and zoology, indicate that we are on the verge of entering another Ice Age, and the data also shows that severe and lasting climate change can occur within only a few years. While concern over the dubious threat of Anthropogenic Global Warming continues to distract the attention of people throughout the world, the very real threat of the approaching and inevitable Ice Age, which will render large parts of the Northern Hemisphere uninhabitable, is being foolishly ignored.

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FIGURES

Climate Data Over Past 420,000 Years, Fig. 1  and Over Past  5,000,000 Years, Fig. 2

Fig. 1 Vostok ice core data 420,000 year record of climate change.

Vostok Ice Core Data over a 420,000 year time span from Petit et al. Nature (1999).

The Vostok ice core samples are astonishing in the wealth of information they contain.  Careful analysis of samples of ancient ice by literally hundreds of scientists has revealed earth's climate history over the past 420,000 years.  Moreover, this extends our knowledge through four previous cycles of  world-wide glaciation and interglacial warming.

It takes some effort to comprehend the amazing detailed data in Fig.1.

First, check the axes. The time axis of the graph starts at zero and proceeds into the past. The temperature data is plotted in the red color curve.   The temperature of what?  Analysis of the Vostok ice cores provides us with an average mean temperature of ancient near-surface ocean water.  

Here are a few simple observations:

Examine the temperature record in the data plot. Notice that the temperature oscillates. That is,  characteristic features in the temperature data repeat in time. The temperature has a periodic nature.

Temperature plotted at the zero of the time axis axis comes from analysis of the most recently formed ice. Ice samples recovered by the Vostok project from deeper deposits provide us with the geochronology of the ice. We get the  properties of the earth's oceans extending back through 420,000 years. Four hundred and twenty thousand years!

Over this long period of time temperatures have varied in a narrow range of approximately 10 degrees Celsius or 18 degrees Fahrenheit.  Further, the most recent temperatures in the plot are not unusually warm for this phase of the climate cycle. This can be seen by comparison to earlier main temperature peaks in previous climate cycles. Can you identify the main temperature peaks? There are five of them in Fig. 1 including the one at time zero.  A previous main temperature peak occurs at approximately 125 thousand years ago. Another is at approximately 240 thousand years ago. What were the maximum temperatures in these previous climate cycles?

Keep in mind these are mean temperatures, averaged over many years. Daily and seasonal temperature oscillations are averaged-out to give the average mean temperature. This type of data is, therefore, well suited for the study of long term climate cycles.

How do you get the ocean temperature from ice samples?

This fascinating temperature data was obtained from hydrogen isotope concentration measurements in ancient frozen ice samples retrieved from deep under the surface of an antarctic glacier.

How does that work?

It turns out that hotter near-surface ocean temperatures tend to concentrate the amount of deuterium (D), the heavy hydrogen isotope, in near-surface ocean water. This results in higher D/H ratios in the ice. This is handy since the main constituent of oceans is water consisting of DHO and H2O molecules.  When this ocean water is frozen and trapped in an ice sheet, the D/H ratio stops changing. Hence, careful measurement of D/H concentration ratios from the ice core gives temperature as a function of depth and time. Really a simple concept, but  requiring lots and lots of very careful work by many scientists involved in the Vostock project. The result of their prodigious effort has produce the data plotted in Fig. 1, which we can now examine. 

What else is plotted in Fig. 1?

What about CO2?
During the freezing process tiny bubbles of air are trapped in the ice. When ice core samples are examined as a function of depth, we have a time history of the composition of earth's atmosphere preserved in those air bubbles.

How did atmospheric CO2 concentration change over these climate cycles?  

Examine the CO2 concentration history shown in the blue curve in Fig. 1.

Notice that atmospheric CO2 concentrations (ppmv: parts per million by volume)  in past climate cycles are comparable, and in some cases larger, than present day values.

[We need to put in a reference for present day atmospheric CO2 concentrations, and near surface ocean temperatures from isotope analysis. Woods Hole guys may have this.]

When compared to previous climate cycles in Fig. 1, present day atmospheric CO2 concentrations do not appear to be anomalously high or low. Rather, they are comparable to CO2 levels near and after the onset of global cooling phases of previous climate cycles. This is inter-relationship is explained in more detail in the article by Gregory Fegel, excerpted above, and in the following section, "Earth's Oceans, Lakes, and Streams Regulate Atmospheric CO2."

Want more information on the Vostok ice core data?
  

Here is a link to all of this data along with extensive published references and detailed discussion of the analysis techniques.  http://www.ncdc.noaa.gov/paleo/icecore/antarctica/vostok/vostok_data.html
Dig in!

What causes Climate Change?
The frequency of these temperature oscillations is predicted with remarkable accuracy by precise mathematical physics calculations of orbital mechanics of the Earth, Sun, Moon system. This calculation is credited in the above article and is called Milankovich Theory.

[The success of Milankovich theory in predicting the frequency of climate cycles (ice ages and warm interglacial periods etc.) is roughly equivalent to the success of quantum mechanics in predicting the optical line spectrum of the hydrogen atom. Such agreement is considered substantial confirmation of physics based theories.]

The Milankovich theory successfully predicts these climate cycles without need of further assumptions.  The beauty of the Milankovich theory is that it predicts the main features of climate cycles from a very simple understandable process. When the earth is exposed to more intense sunlight on average, it gets warmer.

One can embellish this picture by adding other effects. For example, the known physical changes in the light output of the sun, sunspot epochs and the like, or changes in the solar wind hitting the earth can be added to the mix.  Further, one can include corrections to the earth's overall infrared emissivity factor caused by atmospheric carbon dioxide and changes in the reflectivity of the earths surface or albedo. Albedo is a measure of how deserts and ice sheets reflect more sunlight back into space than do forests. Deserts tend to cool the planet. All very interesting, however, these processes do not appear to be needed to explain the main features of climate cycles. Milankovich seems to have gotten it right.


Earth's Oceans, Lakes, and Streams Regulate Atmospheric CO2

Carbon dioxide (CO2) is present in gaseous form in the atmosphere as we have all heard. CO2 also exists in water as a solution. CO2 dissolves in ocean water like it does in a can of carbonated soda. There is a natural tendency for gaseous CO2 in the atmosphere to equilibrate with CO2 dissolved in earthly bodies of water. The rate of this equilibration is governed by solution chemistry and transport processes. Generally, increasing atmospheric CO2 drives more CO2 into solution, and visa-versa.

Ocean temperature plays an important role in this equilibration. Hotter ocean temperatures tend to drive more CO2 out of solution and into the air. That is, higher ocean temperatures cause increased atmospheric CO2 concentrations by this mechanism.  One can expect that long timescale variations in atmospheric CO2 are strongly coupled to ocean surface temperature. We can say that earth's oceans, lakes, and streams are huge reservoirs for storage and release of CO2.  True for other gases too.

Atmospheric CO2 is also converted into non-gaseous molecules by chemical reactions including various bio-metabolic processes. Plant photosynthesis removes CO2 from the atmosphere.  In oceans, shell formation by plankton and other shelled creatures sequesters carbonates permanently. For example, great geological deposits of chalk consist of  shells from deceased microscopic sea creatures, accumulated over eons. Such shell formation can be viewed as a process that removes carbonates from the ocean permanently. Natural sequestration of carbonates.

The above qualitative discussion highlights some important geo/biochemical process that tend to regulate atmospheric CO2.  However, atmospheric CO2 concentrations themselves do not seem to play a primary causative role in Earth's climate cycles. Climate cycles on Earth seem to be largely explained by the Milankovich Theory.

Now back to the data....

Also plotted in Fig. 1 are:

The methane concentration indicator (CH4), the Oxygen 18 indicator (An indicator of global ice mass? Some discussion on this below.  Expert comments welcome.), and the solar radiation indicator roughly proportional to the total averaged power from the sun (mostly in the form of light) that was striking the earth at the given time period.

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Break Time and a Pop Quiz

Now for an entertaining thought experiment.  In thought experiments we get to ask: "What happens if we could ....?"

Here's an interesting one.  What happens if we could ....

Put the earth in a huge thermos bottle (Dewar flask for chemistry majors). No light or heat gets in from the sun, and nothing gets out of the bottle.

After the earth is in the bottle, we start monitoring the near surface ocean temperature.

Q1: At first the ocean temperature would  (1) increase  (2) decrease  (3) stay the same.

Q2: In the long term the ocean temperature would eventually have to (1) increase (2) decrease (3) stay the same.

If you know the answer please leave a comment.  Explain your choice.

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What about the past Five Million Years? 

Further data and discussion on global temperature fluctuations, ice ages, warming ages. 

The five million year history of global climate variation from Lisiecki and Raymo in the journal  Paleoceanography (2005).

Fig. 2  Five Million Years of Climate Change from Analysis of Ocean Floor Sediment Cores [Lisiecki and Raymo in the journal Paleoceanography (2005)]

Here Delta-T is the temperature variation relative to the present era baseline. Delta-T is inferred from measured variations of Oxygen 18 concentration in deep sea floor core samples. The time scale in Fig. 2 covers the past 5 million years. The present era is at “year zero” on the time axis and time marches backward to the right. See below for details of data analysis.

A few observations about the data in Fig. 2 follow.

First, very near the year zero time, one can see a strong warming trend immediately after the most recent temperature minimum. The minimum occurred at roughly 0.05 million years before the present. This most recent temperature oscillation corresponds to the most recent ice age and the subsequent present day warming trend.

Going back further in time, one sees repetitive short term warming and cooling oscillations. This relatively rapid cycle repeats on a roughly 50 kyr to 100 kyr timescale. Over the past few million years this oscillation frequency is trending toward lower frequencies. Also evident in the Fig. 2 data is a long term cooling trend during the past 3 million years.

Mysterious magnetic pole migration and flipping.
Another geophysical curiosity is the phenomenon of polarity transitions in the earth's magnetic field. Paleo-oceanographic records from other research projects have shown the earth's magnetic field undergoes periodic transitions called pole-flips. During these pole-flips, the north and south magnetic poles move around and exchange positions. Magnetic pole-flips are generally believed to be the result of a magnetohydrodynamic dynamo instability. As yet there is no quantitative physical theory of this phenomenon. Interestingly, some planets like Mars and Venus have little or no geophysical magnetic field.

The most recent of Earth's magnetic pole-flips occurred about 780,000 years ago. Did that pole flip disturb the temperature oscillations in Fig. 2? On casual inspection I cannot see anything unusual at that time. Of course, the climate effects of the pole-flip may have been only a short term transient of duration less than 1000 years, maybe much less. It would be interesting to obtain ice cores at 780,000 years at depth of ~6000m (don't know if such ice deposits exist) and use Vostok like techniques to look for evidence of climate effects of the pole flip.

Here is a link to a detailed cartoon diagram of the Vostok region.
http://www.sale.scar.org/images/new_vostok_cartoon_high.jpg

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Side Bar: Why are the temperature fluctuations smaller one to five million ago?


As an expert at reading and analyzing time series data, but non-expert in paleo-oceanography, I want to mention an interesting feature of the data in Fig. 2. Namely, the amplitude of temperature oscillations seems to systematically decrease going back in time, over millions of years. 


Here is a brief side bar on my personal thoughts on this apparent trend toward lower fluctuations evident in Fig. 2. 


Is it real or maybe an artifact?


Maybe the climate cycles were less severe one to five million years ago, or maybe there is a systematic error  smoothing out the delta-O18 oscillations in older, deeper sediments.

One can ask: What would be the affect on the data analysis if concentrations of heavy carbonate molecules, those carrying the O18 isotope, undergo some diffusion while buried  in the sediment layers?

Diffusion of molecules would tend to smooth out O18 concentrations making the temperature oscillations look smaller. Moreover, there would be a greater smoothing effect in older sediments, in part because diffusion would have a longer time to act. Interestingly, such diffusion would not change the frequency of the oscillations much, just round them off and smooth out the bumps.  The delta-O18 oscillations would tend to get smoother as one goes back in time. Which is what they seem to do in Fig. 2.

What factors affect diffusion rates of carbonate molecules in deeply buried sediments?

Diffusion rates are governed by the diffusive transport coefficient, D, of the material containing the O18 carbonate concentrations. Larger values of D make for more rapid smoothing of concentration gradients.

We can make some qualitative statements about factors affecting the value of D. Generally increases in D can be expected for sediments subject to (1) increased temperature as a function of depth (2) changes in the micro-structure and porousness of the compressed solid state, (3) increased pressure as a function of depth, (4) variations in composition. Overall, I would expect the transport coefficient D to be an increasing function of depth under the sea floor.

All of this is rather straightforward, and is probably well-known by experts in this field. Undoubtedly, the authors were aware of this. They may have determined that diffusion is negligible after all, or it may be that values of D are simply not available because of the uncertainties mentioned.

Perhaps the long term drift to smaller amplitude temperature oscillations going back over five million years, may in part be an artifact of this diffusion process. It seems at least plausible and worthy of more discussion.

Expert and Non-expert comments welcome on this topic.

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Now ...  back to the analysis methods used to get Fig. 2.

What is delta 18-O and delta 18-O Benthic Carbonate?

In both Fig. 1 and Fig. 2 a quantity called “delta of oxygen 18” is plotted. These quantities in the data plots actually refer to somewhat different drilling and analysis methods used by authors of the two referenced papers. Below is a brief overview of this type of oxygen 18 analysis and theory.

In Fig. 1 the data comes from ice cores obtained by drilling into deep ancient ice in the Antarctic. The deeper the ice, the older the ice. In fact the top axis in Fig. 1 gives the depth of each ice sample in meters and the bottom axis gives the corresponding age of the ice deposit obtained from that depth.

In Fig. 2 drilling cores come from the sea floor and consist of deep layers of accumulated sediment. Chronology is again established from the-deeper-the-older concept. In both studies oxygen isotope analysis is used on material samples from the drill cores.

Here is a rough explanation of this isotope analysis.

Oxygen atoms come in two isotopes 16O and 18O having atomic mass 16 and 18 respectively. Any sample of oxygen from nature will contain both isotopes. The ratio of these concentrations is a measurable quantity called the concentration ratio, and it's average value (over many locations and samples) is called the natural isotopic abundance ratio. This is true for oxygen gas, dissolved oxygen, and for oxygen in molecules like carbonates. Importantly, there are isotope enrichment processes that occur in the ocean. These include physical processes such as diffusion and evaporation which tend to mobilize the lighter isotopes leading to small but measurable variations of the isotope abundance ratios. Moreover, these physical processes are strongly dependent on the ambient temperature. Hence, their effects, such as concentration changes, can be used as an indicator of temperature change. The laboratory techniques for isotope abundance measurements are amazingly accurate when done by experts.

Next, we need samples of material to analyze.

Scientists go "into the field" to collect these samples. Core drills similar to those use for oil exploration are used to extract cylindrical sections of subsurface material. Scientists keep track of the depth below surface giving the geochronology of the material.  The data in Fig.1 were obtained from drill core samples from an expedition to a south polar ice sheet. The data in Fig. 2 is from drill core samples from the ocean floor. These samples are then taken back to the lab for analysis, like the CSI the guys on TV.  Measurements of the oxygen-18 oxygen-16 isotope ratios can be done with great accuracy using sensitive mass spectrometers and thermal desorption techniques. As you can imagine it requires a huge amount of scientific work to get the data that is plotted in the above Figures.

In order to track the natural isotope enrichment history, one tracks the deviation in the enrichment from the natural isotope ratio. The deviation from the natural ratio is referred to as “delta 18O” and is the quantity plotted in the Figures.

What does "benthic carbonate" mean?

The term “benthic carbonate” refers to carbonate samples that originated in the benthic zone. The benthic zone is the ecological region at the lowest level of a body of water such as an ocean or a lake, including the sediment surface and some sub-surface layers. Benthos are organisms inhabiting the benthic zone. [Wikkipedia]

The plot, Fig. 2, of  “delta 18O from benthic carbonate” refers to oxygen isotope analysis of calcium carbonate, CaCO3, deposits from drill core samples obtained from the sea floor. The calcium carbonate is believed to originate from skeletal remnants, shells, bones etc. of bottom dwelling foraminifera and from accumulated skeletal remains of other ocean dwelling creatures.

What are bottom dwelling foraminifera? (This lovely definition from Steven J. Gould, I think.)

"Bottom dwelling foraminifera are sea creatures that crawl, walk, or slither around on the sea floor."


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Scientific quality variations in the field of climatology.

Examples of sloppy thinking and common misconceptions regarding the above data in a Wikipedia article from 2009

Popular discussions of these climate data range from thoughtful, to careless, to bordering on disinformation. The following example is from a current Wikkipedia entry (dated 2009) relating to Fig. 2. My comments and corrections are added in italics.

Wikipedia Article Text and Judgmental Comentary

Figure 2 above is from the paper of Lisiecki and Raymo (2005). It consists of data from combined measurements on 57 globally distributed deep sea sediment cores. The measured quantity is the oxygen isotope fractionation [sic] (delta 18-O) in benthic foraminifera [not clear such foraminifera are the sole source for delta 18O, some discussion needed here] , which serves as a proxy for the total global mass of glacial ice sheets. ["(delta 18O) a proxy for total global mass of glacial ice sheets"??  Lisiecki and Raymo use the delta-18O as an ocean temperature indicator, as is evident in Fig. 2. The main figure in their paper!]

[As far as I can see, the quantity "delta 18O" is an indicator of variations in ocean temperature. Considerably less clear, and likely to be nonsense, is the assertion that delta 18O may be a strong indicator, e.g. proportional to ... The mass of all the ice on the surface of the earth, as claimed by the Wikipedia person] 


[More discussion and Expert comments welcome!]

Lisiecki and Raymo constructed this record by first applying a computer aided process of adjusting individual "wiggles" [sic] in each sediment core to have the same alignment (i.e. wiggle matching) [sic].


 ["wiggle matching" is not a scientific term. The author may be referring to timeseries data analysis techniques including, periodogram, spectral analysis, and other more sophisticated mathematical tools used  for analysis of periodic and quasi-periodic data. "wiggle matching" sounds like nonsense and it is. It seems likely the wiki author has no understanding of the actual methodology used in the hard sciences to establish geochronology of the core samples in the referenced papers.] 

Then the resulting stacked record is orbitally tuned [sic] by adjusting the positions of peaks and valleys to fall at times consistent with an orbitally driven ice model (see: Milankovitch cycles).

[Here the term ‘orbitally tuned’ is used by the wiki authors to describe well-known cycles of insolation caused by variations in the earth’s orbit and it’s slowly changing axis of rotation. These cycles can be calculated rather precisely using Newtonian mechanics and can be extended into the distant past, even back to 5 million years ago.] 


 Both sets of these adjustments are constrained to be within known uncertainties in sedimentation rates and consistent with independently dated tie points (if any). Constructions of this kind are common, however they presume that ice sheets are orbitally driven, and hence data such as this cannot be used in establishing the existence of such a relationship.

[If you find the above Wikipedia text confused and unclear, you would be correct. It is in fact poorly written.]

[It seems likely that the Wiki authors do not appreciate the mathematical precision of such calculations. They are not ’assumptions,’ rather they are mathematically calculated quantities stemming from basic Newtonian orbital mechanics.] 

The observed isotope variations are very similar in shape to the temperature variations recorded at Vostok, Antarctica during the 420 kyr for which that record exists. Hence the right hand scale of the Figure was established by fitting the reported temperature variations at Vostok (Petit et al. 1999) to the observed isotope variations. Hence, this temperature scale should be regarded as approximate and its magnitude is only representative of Vostok changes. In particular, temperature changes at polar sites, such as Vostok, frequently exceed the changes observed in the tropics or in the global average. A horizontal line at 0 °C indicates modern temperatures (circa 1950). [This is peripheral criticism.]

[The data in Fig. 2 clearly show the variation in the temperature indicator over an extensive time interval with very nice time resolution. These features of the time series are independent of the absolute temperature calibration factor.]   


[That is, the Fig. 2 data give us a clear picture of cyclic oscillations in temperature that is more important than their precise magnitude. Moreover, the evident quasi-periodicity of these data is in quantitative agreement with well known secular changes in the earth's orbit and rotation axis orientation.]


[The success of Milankovich theory in predicting the frequency of climate cycles (ice ages and warm interglacial periods etc.) is roughly equivalent to the success of quantum mechanics in predicting the optical line spectrum of the hydrogen atom. Such agreement is considered substantial confirmation of physics based theories.]

Labels are added to indicate regions where 100 kyr and 41 kyr cyclicity [sic] is observed. These periodicities match periodic changes in Earth's orbital eccentricity and obliquity respectively, and have been previously established by other studies (not relying on orbital tuning).

Wiki authors do not give a satisfactory discussion of the significance of their term "orbital tuning" in this context.

For discussion of how such orbital changes might drive climate change, see Milankovitch cycles.

[This Wiki article, from 2009, is an example of sloppy analysis and bad science. Sadly it seems rather typical of the low scientific and analytical standards of the literature promoted by Believers.]