Archive for the ‘Uncategorized’ Category

Thankyou and a road map!

February 12, 2010

I want to extend a very big thankyou to everyone who has taken the time to visit, read and then, perhaps, pass a comment. The debate has been challenging, stimulating and above all polite.

Now I want to move on and consider some key topics and concepts in palaeoscience. Many of these will relate to my area of expertise which is isotope geochemistry and how we can use isotopes to help us characterize natural processes, reaction paths and kinetics. A subject that crops up time and again on the blogs is the oxygen isotope thermometer as applied to ice core, whether it be high latitude, polar or high altitude, tropical. My current idea is to present some of the underlying fundamentals and then move on to discuss some key papers, highlight unresolved issues and hopefully assess the robustness or otherwise of our estimates of past temperatures on different time scales: the last few centuries, the Holocene and then the glacial. Where possible I’ll post pdf’s of papers, raw data and calculations. I’ll also post copies of my lecture notes and some new material that I’m preparing for a new course, that hopefully will translate into a book.

At the same time as writing this blog I also currently hold a university teaching fellowship. During this tenure I am introducing open notebook science into my teaching and encouraging my research students to move over to an open notebook format. Data from my research will be archived and available in as close as real time as possible to my students, other scientists and you. Over the next 3 months I am embarking on an analysis of the hydrogen isotope composition of the Gomez Glacier, Antarctica. There will be about 2,500 sample analyses and about 1000 analyses of standards. These can be combined with my existing oxygen isotope data base and will provide the most detailed and documented set of analyses for an Antarctic Peninsula ice core yet done. The combined oxygen and hydrogen isotope data set will allow us to assess temperatures and source region conditions (temperature, humidity etc.) over the 150 year record of the core. I hope that by making this project public we will all learn a lot, and perhaps discover new insights into the data that may have hitherto been unseen.

It is with some trepidation that I do this. First is I need to get comfortable with the IT technology etc. I need to structure this blog appropriately so that information is readily available to those who want it, yet discrete for those who may be more interested in reading opinion pieces etc. and who don’t want to share in this ‘experiment’. Second, this is a very public demonstration of how I do science and I’m not very aware of how others have approached this, or what their experience has been. Many of my lab book entries will be tedious and concern issues of calibration, fault finding, validation etc. and sometimes the rate at which data appears may be slow. There is a real chance I might make a prat of myself. On the other hand I think it so important that others can share in my science that the benfits will far outweigh any negatives.

So please bear with me over the next week or so as I try and set this up. As background, over the weekend I’ll post copies of my Gomez Glacier work and the data base. They already exist at , but it will be easier if I collate them all at a single site.

Once again thankyou all for visiting the site.

Jerome Ravetz and Post-normal science

February 10, 2010

UPDATE: Thursday 11th February 18.23

Scientist for Truth has provided a link to a very powerful essay on Jerome Ravetz and PNS at:

In it he sets out clearly the philosophical background to PNS. Scientist for Truth argues that PNS has little, or nothing, to do with science, and everything to do with a political philosophy. I urge readers to read it. All the comments here have been very stimulating and I think you will enjoy this  article which had slipped under my radar.


The essay posted by Jerome Ravetz over at WUWT has caused quite a stir and provoked some heated debate. For those who haven’t read it I urge you to do so. It can be found here:

It is a closely argued analysis of Climategate and a defense of it within the context of post-normal science. Ravetz argues that we can understand the current climate hysteria if we understand that the scientists were practising normal (Kuhnian) science when in fact ‘climate science’ is actually post-normal. What do we mean by these terms and how does climate science fit into the picture.

As I understand it the Kuhnian view of science is rather analagous to the punctuated equilibrium theory of evolution. We practise our science within a current paradigm and carry out experiments to falsify that paradigm. Over time observations that lie outside the explanatory power of the existing paradigm accumulate and when they reach a significant level a revolutionary phase in science occurs in which a new paradigm rapidly develops and takes over. Following this step change in understanding we are in a new period of stasis or equilibrium in which we fill out the new picture, using the scientific method and putting the bits of the jigsaw puzzle together. A good example might be Continental Drift. Whilst Wegener proposed, in the early part of the 20th century that the continents must have wandered over the planet because of the apparent fit of the continental margins most geologists still worked within the paradigm of geosynclines arguing that only vertical movements of the earth’s crust occurred rather than major horizontal movements. It was only with the discovery of magnetic stripes on the ocean floor, the mid-ocean ridges, and fault plane solutions for transform faults etc. that were inconvenient to the geosyncline view of the earth that we entered the revolutionary change in our understanding that we now know as plate tectonics. It is now inconceivable to us that any other view existed. We might also think of the earth centred and heliocentric views of the solar system, Newtonian gravity and relativity as other examples. It is important  to remember that at the time a paradigm is dominant it does have explanatory and predictive properties that allow us to test it’s key tenets. When the model fails it is proven to be in error and a new paradigm is required.

We can study components of the climate system in exactly the same way, developing hypotheses and using experiment to falsify these. Our paradigms are the currently understood laws of physics. We can apply these in hypotheses and develop experiments to test these. An example is the CERN CLOUD experiment which aims to determine if galactic cosmic rays can interact with the atmosphere to produce cloud condensation nucleii. Thus climate science is essentially using physics and chemistry to understand the way the climate system works and how it responds to radiative forcing.

In this Kuhnian view of science there is no role for advocacy. We objectively question nature and seek truth.

In contrast Ravetz argues that climate science is a post normal science. He suggests that the reason for the predicaments many climate scientists find themselves in is that they have been practising Kuhnian science in a post normal science field. This is a difficult concept to fully understand. However, what Ravetz suggests to us is that Kuhnian science is exact with little understanding of probability, errors, and uncertainties. He even suggests that science students today are taught little about these concepts. In contrast he characterises post normal science as one where the facts are uncertain, the values are in dispute, the stakes high and decisions are urgently needed. Thus we see that for Ravetz climate science is predicated on the fact that  the climate is warming at an alarming rate, that we have great gaps in our knowledge, and that urgent decisions must be made.

Because of the gaps in our knowledge the approach to post normal science is different to the Kuhnian approach. Ravetz suggests that there is a wide stakeholder community that should be included in peer review, the so called extended peer community. This peer community can bring their own ‘local knowledge’ or ‘extended facts’ to the debate. It strikes me that this is another way of trying to seek concensus, rather than knowledge, truth and understanding.  In many ways it strikes me as another description of what Feynmann would call ‘cargo cult science’.

To me Ravetz’s analysis is deeply flawed. The only approach we can take is that of the scientific method and use our knowledge of physics and chemistry to develop plausible hypotheses which we can test. If an idea cannot be developed into a testable hypotheses it remains just an idea. The theory of CO2 induced catastrophic global warming is just that: an idea that cannot be experimentally falsified. In the absence of any direct ability to test the idea we must apply common sense or Occam’s razor. For example the principle of uniformitarianism suggests that if CO2 is the dominant forcing component in the climate system then there should be abundant evidence of temperatures scaling with CO2 levels. As a first order test we can look at the Eemian intergalcial about 125,000 years ago. During this period CO2 levels were about 280ppm (100ppm below present day levels) and temperatures several degrees warmer than present. Here we see immediately that temperature is not a simple function of atmospheric CO2 levels and we have to look at other components in the climate system to explain the Eemian climate.

Where does this leave us. I suggest that post normal science is a social construct without meaning. It fits the current zeitgeist in which humanity is vulnerable to a multiplicity of disasters: epidemics, nuclear obliteration, global warming etc. The characterization of Kuhnian, and the scientific method as having no regard for probability, error, uncertainty and only being applicable to well controlled experimental systems in the laboratory is wrong. Finally, the only way we can fully understand the climate system is by using what we all know as the scientific method.

Why Harmonic Oscillator?

February 9, 2010

I have a presentation which I sometimes give when asked to talk at schools science fairs called ‘From atoms to climate change’. It’s designed to engage with young chemists, physicists, biologists, geographers and geologists. In the talk I try to show how we can move from the fundamental properties of molecules at the quantum level to using variations in the abundance of stable isotopes of the light elements in nature to determine past climate change. We then look at the climate throughout the Phanerozoic from 560 Ma to the present. One of the take home messages from the talk is that our interpretation of the data has to be grounded in a thorough understanding of the underlying physics and chemistry.  The other one is that you are never too young to start playing with springs and balls (as models of molecules) and having fun with science. Which brings us to the harmonic oscillator. 

Equilibrium isotope partitioning between molecules is driven mainly by the Zero Point Energy (ZPE), that is the quantum mechanical requirement that molecules vibrate with a half quantum of energy even when they are in their ground states at absolute zero. This is a consequence of Heisenberg’s uncertainty principle. Close to the equilibrium inter-atomic distance in a molecule the potential energy, usually represented by a Morse potential, can be approximated by a harmonic function and the vibrational modes by a harmonic oscillator.  If we substitute one of the atoms of the molecule with an isotope of the same element we change the zero point energy of the molecule and thus the vibrational frequency of the bond. The difference in zero point energies between the isotopically substituted and non-substituted molecules is small, typically a few ten’s of joules per mol, but enough to drive measurable isotope partitioning between molecules in nature.

Hence the blog is called Harmonic Oscillator as it provides the fundamental link between physics and the effect of temperature on isotope partitioning and thus our ability to use isotopes to measure past earth surface temperatures.

Convoluted I know but an illustration of how my mind works.


February 9, 2010

Welcome to everyone who finds their way to my blog. As many of you will know I achieved minor celebrity status last week as a bit-part player, almost an extra, in the climategate saga.  However for those of you who don’t know me here are a few words. I’m Paul Dennis, an isotope geochemist and Head of the Stable Isotope Laboratories at the School of Environmental Sciences, University of East Anglia. This blog is my personal site where I can write about any science that interests me, describe my research and give my take on ideas, and views on issues of interest. More importantly it’s somewhere I can engage with you on science. Science impinges on all our lives in many ways and we are all part of the adventure. The man on the Clapham omnibus has as much right to engage in science as I do. So please take this as a welcome to debate and discuss.

I’ve been described in the press as a climate scientist. I’m not. First and foremost I’m a geochemist with interest in many subjects. My research has wandered over the fields of solid state physics, point and line defect properties of silicate minerals, solid state transport processes, phase transformations, mineral deposits, isotope hydrology and hydrogeology, palaeoclimates, the earth in deep time, beam transport systems and mass spectrometer instrument design and construction. Some may say I’ve been a bit of a scientific dilettante. More I see myself as enjoying science in its widest sense. Perhaps it gives me a different and wider perspective. If I don’t understand something I want to take it apart, find out how it works and then try and put the pieces back together again.

So now you have some background please bear with me as I, possibly slowly, build this site. Feel free to comment, critique and give advice. At many times the postings may read like a diary. I hope they give you some idea of my scientific world, my lab and my research.

I’ll start with a posting on why I’ve called the blog Harmonic Oscillator, but that’s for tonight.

Best wishes to all.