Be the next associate professor of Quaternary Palaeoecology in Bergen

As pollen analysts who use Fægri & Iversen (1950-1989) “Text book of pollen analysis” will know, Bergen University has a long and active tradition of Quaternary Palaeoecology.

Knut Fægri was active in the Botany department for over fifty years, and in addition to writing the standard textbook for pollen analysis and many other things, worked on pollen from over fifty sites.

The Botany Department has since been merged into the Biology Department where an active group of palaeoecologists collaborate with modern ecologists to understand how, and why, natural ecosystems change over space and time. Our primary goal is to ‘reconstruct the past, study the present, and model the future’ and to study, quantify, and understand the natural variability of ecosystems and the multi-layered impact of human activity.

Our palaeoecologists include

  • Hilary Birks who has a special interest in plant macrofossils, focusing on the late-Glacial. She has a built up a huge macrofossil reference collection, which complements our pollen reference collection. Her work was recently celebrated in a special issue.
  • John Birks whose work on quantitative methods in palaeoecology is well known and recently celebrated in a special issue. He was a key contributor to the work demonstrating the influence of acid rain on lake acidification. He is also keen on alpine plants and spy literature.
  • Peter Emil Kaland who was recently knighted for his work on coastal heathlands
  • Aage Paus who focuses on late-Glacial environmental change
  • And someone who writes occasionally sarcastic blog posts when not thinking about diatoms.

These staff members are joined by excellent and friendly postdocs and PhD students working on niche modelling and other numerical problems in palaeoecology and trying to reconstruct UVB radiation from biomarkers in pine pollen.

We work in a new building with well appointed laboratories supported by two technicians, and have close collaboration with other palaeoecologists and other Quaternary scientists in Bergen. Including:

  • archaeologists at Bergen Museum
  • glaciologists in the Department of Geosciences
  • climate modellers in the Bjerknes Centre
  • researchers using pollen, chironomids and foraminifera in the Bjerknes Centre and Uni Research.

We have a vacancy. Would you like to join us and extend and enhance our work?

Posted in Uncategorized | Tagged | Leave a comment

Truth about ocean plastics is elastic at WUWT

From turtles mistaking plastic bags for jellyfish, to dolphins getting entangeled in discarded fishing nets, and the injection of persistent organic pollutants absorbed into plastics, plastic pollution in the ocean is harmful to marine life.

Eriksen et al have a new paper out about the amount of plastic pollution in the oceans. The Guardian wrote about it, so did Willis Eschenbach at WUWT. No prizes for guessing whose coverage was more accurate.

Eriksen et al report that the world’s oceans contain about 270 thousand tonnes of plastic. Eschenbach divides this mass by the volume of the ocean (1.3 billion km3) and reports that 200 g km-3 is nothing to get passionate about. This is, after all, only an order of magnitude higher than the concentration of gold in the ocean.

However, Eschenbach is straining to mislead the reader. The data Eriksen et al synthesise comes from surface net-tows and visual observations of large plastic debris at the surface. This is data on the uppermost metre (or less) of the ocean, not the entire ocean volume. Consequently, Eschenbach’s estimated concentration is out by at least factor of 3790 (the average depth of the ocean is 3790 m).

Even for WUWT, this is a bad estimate.

Posted in Fake climate sceptics, Peer reviewed literature | Tagged , | 1 Comment

Private prosecutions as an alternative to publications

When you read a paper you disagree with, you have a number of options. The easiest is to shrug one’s shoulders and mutter darkly that nothing better could be expected from that lab. More productively, one can write a blog post exposing the papers weakness; run the gamut of hostile reviewers and editors to try to publish a comment that rebuts the paper (if the journal accepts correspondence); or publish a new paper that will convince everybody (or not). There is a radical alternative: to submit an allegation of research misconduct to the author’s university. When the complaint is dismissed, ask the police to investigate the author for misconduct in public office. When they decline, engage solicitors to bring a private prosecution against the university registrar who dismissed the original complaint.

Who would do this? Why none other than Douglas Keenan, with the story blithely promoted by Andrew Montford at the Bishophill blog.

Keenan’s complaint is against Christopher Ramsey, a professor at Oxford University who developed the OxCal program for calibrating radiocarbon dates. Christopher is always exceptionally helpful when users get stuck when using OxCal (as I often do) – he is a very valuable member of the palaeoecology and archaeological community. What did he do to incur Keenan’s wrath?

Keenan’s initial complaint contained two allegations. The first was that Ramsey continues to use standard methods for radiocarbon calibration rather than adopting Keenan’s proposed alternative. This was not surprising – Keenan’s suggested procedure for calibrating radiocarbon dates was nonsense, and eventually even he admitted that and withdrew that part of the complaint. I note he has still not retracted his paper. Research misconduct?

The second allegation was that Ramsey had used some inappropriate statistical methods. Keenan failed to show that the choice of methods made any material difference to the results.

Keenan’s complaint was withdrawn and reissued with a new allegation that Ramsey had failed to consider the potential bias of volcanic CO2 on radiocarbon dates from Thera.

Thera was a volcano in the Aegean Sea that erupted about 1600BCE, destroying most of the island in one of the largest Holocene eruptions. The eruption of Thera is a key chronological marker in the archaeology of the Eastern Mediterranean, and the date is contentious. Estimates based on Egyptian dynastic chronology suggest that the eruption may have occurred over a century later than indicated by radiocarbon dating. This discrepancy potentially points to errors either in the radiocarbon dates linked to the eruption, the dynastic chronology, or the evidence (mostly pottery) used to tie Thera into the dynastic chronology.

Carbon dioxide emitted by volcanoes contains essentially no 14C, so if it is incorporated into organisms it will bias radiocarbon dates. If a sample contains 1%  volcanic carbon, it will appear to be 80 years too old. This is well known – plants growing near fumaroles and other vents appear to be hundreds of years old – and has even been shown from Santorini, the remnants of Thera. This effect decays rapidly with distance from the vent.

The potential for volcanic, or other sources depleted in 14C, to bias the dates of the Thera eruption are discussed by Wiener and Earle (2014). Höflmayer (2012), who previously supported the younger date for the Theran eruption, argues that as the dates from several different contexts on Santorini, Crete, and elsewhere are concordant, it is unlikely that incorporation of volcanic CO2 by the samples from Santorini is important. Further, he shows that changing the statistical methodology, avoiding (I think) Keenan’s second accusation, the result is essentially unchanged. Höflmayer (2012) suggests that the dynastic chronology may contain some errors and that some of the archaeological evidence linking the Theran eruption to the Egyptian chronology is more uncertain that previously thought. When these potential errors are taken into consideration, the offset between the archaeological and radiocarbon dates is greatly reduced.

The age of the Theran eruption remains contentious, but Keenan has turned what should be a matter for research and debate into a legal action.

In the unlikely event that Keenan’s private prosecution ever reaches court, I predict it will not end to his satisfaction. The judges who sat on Simon Singh’s appeal against the British Chiropractic Association proved reluctant to adjudicate on scientific disputes

We would respectfully adopt what Judge Easterbrook, now Chief Judge of the US Seventh Circuit Court of Appeals, said in a libel action over a scientific controversy, Underwager v Salter 22 Fed. 3d 730 (1994):
“[Plaintiffs] cannot, by simply filing suit and crying ‘character assassination!’, silence those who hold divergent views, no matter how adverse those views may be to plaintiffs’ interests. Scientific controversies must be settled by the methods of science rather than by the methods of litigation. … More papers, more discussion, better data, and more satisfactory models – not larger awards of damages – mark the path towards superior understanding of the world around us.

Posted in Age-depth modelling, Fake climate sceptics, Silliness | Tagged , | 2 Comments

Q: Why are there no intra-annual patterns in global temperature anomalies?

A: because they are anomalies.

Climate sceptics want to be taken seriously. They want to hold joint conferences with climate scientists. It is not impossible for climate sceptics to do good research, though whether the odds are better than a monkey typing Hamlet is unclear on the evidence below.

A few weeks ago, Willis Eschenbach posted some CERES total solar irradiance (TSI) data at WUWT that showed that TSI varies from about 330 to 350 W m-2 over the course of a year. Eschenbach wondered why this >20 W m-2 difference was not obvious in the global temperature record.

… where is the effect of the ~ 22 W/m2 annual variation in the amount of sun hitting the earth?

He has some ideas. But not good ones.

To get an idea of the predicted effect of this variation in TSI, using IPCC figures this TSI change of 22 W/m2 is about the same change in forcing that we would get from six doublings of CO2 … that is to say, CO2 going from the current level (400 ppmv) to the extraordinary level of 25,600 ppmv.

In addition, again according to the IPCC, using their central value of 3°C warming per doubling of CO2 (3.7 W/m2 additional forcing), this change in forcing should be accompanied by a change in temperature of no less than 18°C (32°F).

Now, I can accept that this would be somewhat reduced because of the thermal lag of the climate system. But the transient (immediate) climate response to increased forcing is said to be on the order of 2°C per doubling of CO2. So this still should result in a warming of 12°C (22°F) … and we see nothing of the sort.

One would have hoped that Eschenbach had been interested in climate change long enough to remember some of the basic definitions. The transient climate response is not an immediate response. It is defined by the IPCC as.

… the change in the global surface temperature, averaged over a 20-year period, centred at the time of atmospheric carbon dioxide doubling, that is, at year 70 in a 1% yr–1 compound carbon dioxide increase experiment with a global coupled climate model.

The Earth’s climate will no more show an immediate 12°C response to the intra-annual variability in TSI than a kettle will instantly boil when plugged in. The climate system has an enormous thermal inertia, mainly in the oceans.

But shouldn’t there be some response to this variability in TSI? Yes, but the global temperature anomaly is an anomaly. For each January, the mean of the climate normal period (often 1961-1990) for January is subtracted. Ditto for February and the other months. This processing removes any tendency for Januaries to be warmer or colder than Julys. Eschenbach won’t find the pattern he is looking for because he is looking at the wrong data and he really ought to know this.

But what if he looked in the right place – the variability in absolute temperature as discussed by Jones et al (1999)

The annual cycle of global mean temperatures follows that of the land-dominated NH, with a maximum in July of 15.9°C and a minimum in January of 12.2°C.

Perihelion, the Earth’s closest approach to the Sun, currently occurs in early January. This timing probably mutes the annual cycle in global mean temperature by offsetting some of the hemispheric differences.

Not to be out done, Stan Robertson takes up Eschenbach’s theme without realising that it is nonsense.

… why don’t we see some significant annual cyclic variation of global mean temperature? This is a truly profound question! It ought to keep climate modelers awake all night, every night.

Yawn.

We do need a better class of climate sceptics.

Posted in Silliness, WUWT | Tagged , | 20 Comments

Time to recalibrate those radiocarbon dates?

Radiocarbon dating is probably the most important dating technique for palaeoecological research in the late Quaternary. One complication with 14C dating is that the concentration of 14C in the atmosphere has changed over time due to, for example, solar-driven changes in the 14C production rate. Radiocarbon dates need to be calibrated to correct for this using a calibration curve derived from a huge number of 14C dates on material of known age.

Every few years, the INTCAL community generates an updated 14C calibration curve incorporating new data. This is a fantastic service to the community.

The current version of the calibration curve is INTCAL13, published in 2013. Many palaeoecologists will be working on material (or reviewing manuscripts) where the dates in the age-depth model were calibrated with a previous version of the calibration curve. Should you change to the new version of the calibration curve? This takes some effort, might mean that different papers published on the same core use different calibration curves, but might not make any material difference.

I’m going to explore how much difference it makes below.

Radiocarbon calibration curves

Radiocarbon calibration curves

The main difference between the curves is how far they extend: IntCal13 and IntCal09 go back to 50000 BP; IntCal04 goes back to 26000 BP; and IntCal98 goes back to 24000, but the last 8000 years of this is a straight line.

More detail on the differences between the curves can be seen by plotting the difference of each curve from IntCal13.

Difference from IntCal13

Difference from IntCal13

Before about 12000 years there are substantial differences between the curves. I would want to recalibrate dates if any were older than this.

Difference from IntCal13 in the Holocene

Difference from IntCal13 in the Holocene

During the Holocene, there are some substantial differences between IntCal98 and IntCal13. I would certainly recalibrate any dates calibrated with IntCal98. The differences between IntCal04/09 and IntCal13 are and generally small, but deviate by up to 40 years in a few places.

The uncertainty of the calibration curves have also changed.

Uncertainty in the calibration curves

Uncertainty in the calibration curves

The more recent calibration curves generally have a smaller uncertainty than the older curves. This is especially pronounced before the start of the Holocene.

For chronologies with pre-Holocene dates, it is certainly worth recalibrating and using the latest calibration curve. For Holocene chronologies, the differences between IntCal04/09/13 are probably not enough to change any conclusions except when high precision is required.

Posted in Age-depth modelling | Tagged , | Leave a comment

Tibetan tree-rings and the sun

Via Maarten Blaauw’s Club du Soleil, I’ve found another paper reporting evidence of solar variability in tree-rings from Tibet. The evidence in the first was dubious, is Duan and Zhang (2014) any better?

Readers familiar with this series critically evaluating palaeoecological evidence for solar effects on climate may already have guessed that this is not going to end well. But have patience.

Duan and Zhang generate a 449-year maximum late wood density (MXD) data from Balfour spruce in the southeastern Tibetan Plateau using standard dendroclimate techniques. They use this record to “to reveal the long-term relationship between solar activity and temperature change in the study area”. They are utterly convinced that signal is there.

The analysis of the solar relationship starts with a Pearson correlation between MXD and sunspot numbers: r =  0.193. This is statistically significant, but the r2 is only 0.037, so this is explaining a tiny proportion of the variance in MXD.

The analysis moves on to the obligatory spectral analysis.

Figure 9. (a) The MTM spectral analysis of the MXD chronology over the period 1563–2011. (b) Thirty year moving correlation coefficients between the MXD chronology and solar sunspot number based on raw values, 11 year moving average and 22 year moving average, respectively.

Figure 9. (a) The MTM spectral analysis of the MXD chronology over the period 1563–2011. (b) Thirty year moving correlation coefficients between the MXD chronology and solar sunspot number based on raw values, 11 year moving average and 22 year moving average, respectively.

The multitaper spectral analysis finds a number of peaks that are significant (presumably against an AR(1) null hypothesis – which might not be full appropriate). The 11.7, 54 and 204 year cycles are claimed as solar variability. Since the time series is only 449 years long, there are only just over two 204-year cycles, so this peak corresponding to the de Vries cycle cannot be considered robust. The 54 year cycle is claimed as a fourth harmonic of the de Vries cycle – the first time I’ve seen anyone claiming to find this – looks like special pleading to me. The 11.7 year cycle matches the 11 year sunspot cycle fairly well, and I don’t blame the authors for getting excited. This result merits further investigation.

After the spectral analysis comes a running correlation. This is an analysis that is often done badly, but I have not seen it done worse than done here.  The 30 year running correlation of  MXD with sunspots is occasionally above the significance threshold used by Duan and Zhang, which appears to be the one-sided p = 0.05 level for 30 observations. There is no allowance for autocorrelation in the time series or for multiple testing. Duan and Zhang proceed to smooth both datasets with either a 11 or 22 year moving average and repeat the 30 year correlation. They believe the high correlations to be physically interesting, forgetting that they have induced a very strong autocorrelation and consequently have nearly no degrees of freedom available. The high correlations are an artefact of the smoothing rather than the importance of solar variability.

The paper reviews the literature for solar cycles in tree-rings. I would find the list more persuasive if I had not already discussed discussed some of the studies . It would be better still if the list was not inflated by papers reporting 14C variability in tree rings, which is of course entirely unrelated to any growth response trees might have to solar variability.

This paper offers at best weak evidence for the importance of solar variability, and many of the results are an artefact of the methods.


Duan and Zhang 2014. A 449 year warm season temperature reconstruction in the southeastern Tibetan Plateau and its relation to solar activity. Journal of Geophysical Research: Atmospheres

Posted in climate, Peer reviewed literature, solar variability | Tagged , | 7 Comments

Fossil fuel loving dinosaur

Anthony Watts suggested today that we could use the Cretaceous Period as an analogue for a 2°C warmer world. Excellent idea, we can use that warm period from the past to test how well climate models perform. If they perform well, it will increase the credibility of the model projections for the 21st Century. It’s is such a good idea that someone has already done it.

Oh wait, that not what he means. Watts thinks we can use the Cretaceous as an analogue for what it will be like to live in a 2°C warmer world.

Was the Cretaceous too warm for Earth’s diverse species? Absolutely not – the Cretaceous hosted a bounty of life and biodiversity, the emergence of the first flowering plants, the first appearance of our mammal ancestors. The Dinosaurs dominated the warm Cretaceous for 80 million years, a long period during which life flourished.

Cretaceous species had millions of years to adapt to warm conditions. Our current biota has perhaps a century. Species will need to adapt to the changing climate or migrate potentially hundreds of kilometres, often across human dominated landscapes, to remain in their ecological niche. Rates of climate change can be more important that the magnitude of change for biodiversity.

The dinosaurs didn’t care much about the high eustatic sea levels in the Cretaceous as they hadn’t built cities and nuclear power stations by the sea. Has Watts not noticed that the only dinosaurs are those that continue to promote the burning of fossil fuels, labouring under the delusion that they emit “harmless CO2 emissions.”

Posted in Fake climate sceptics, Silliness, WUWT | Tagged | Leave a comment