Archive for February, 2014

Protons for Breakfast 19 is about to begin…

February 23, 2014

PfB Logo

The nineteenth presentation of Protons for Breakfast is imminent, and so a cascade of preparatory activity has begun.

  • I have read through and responded to ‘questions’ and ‘reasons for attending’ from the 130 people who have signed up.
  • I have revised the PowerPoint files for Week 1 – somehow still finding things to improve.
  • The NPL security staff have been notified
  • The facilities team have been asked to makes sure the air conditioning stays active late on the relevant evening.
  • And the biscuits have been ordered by the catering team.

So I guess that is about that. What can possibly go wrong?

There were a couple of amusing reasons for attending:

  • Accompanying Grandmother
  • Made to come by parent.

And quite a few insightful questions. Several people wanted to know either when we would have ‘proof’ that Global Warming had an anthropogenic origin, or when we would pass ‘the point of no return’, or why people weren’t ‘more concerned’. But a lot of questions were simple puzzles:

  • How do we know there are more stars in the Universe than grains of sand upon the beaches of the Earth?
  • Why do we feel colder when the wind blows?
  • Why does hot water freeze faster than cold water?
  • What is a HD Picture?
  • How do quantum computers work?
  • Can protons become neutrons?
  • Why do our stomachs ‘rumble’?
  • Will the universe ever be totally dark when all energy has been lost?

And many more. I love the diversity of these questions.

Having run these sessions for 10 years now I am constantly surprised at how each group has its own personality.

And I am very much looking forward to getting to know this group and the individuals within it.

By the way, while the course is on, the frequency of blog articles generally declines – sorry: it’s just all I can do.

Happy Birthday Ludwig Boltzmann

February 20, 2014
Happy Birthday Ludwig Boltzmann.

Happy Birthday Ludwig Boltzmann. My colleagues at NPL ate a ceremonial cake.

Last week I spoke with Ludwig Boltzmann’s great grandson: it was an honour and a pleasure.

Gerhard Fasol had e-mailed me to ask for details about plans to re-define the SI units of temperature (the degree Celsius and the kelvin) in terms of the Boltzmann constant.

Gerhard has a fairly impressive scientific CV in his own right, but of course his great grandfather’s legacy stands above his achievements and most other scientists. If there was a Premier league of scientists, he would be in it.

Boltzmann’s essentially took the ‘idea’ that atoms really existed, and turned the ‘idea’ into a detailed theory of matter with quantitative predictions and brilliant insights.

His ideas were not immediately accepted, which in retrospect makes his achievements all the greater. His motto was apparently

Say what is true;
Write the way that it is clear.
And advocate it until it is your opinion!

Physics has several ways of acknowledging the achievements of its ‘stars’. Their name can be used for an Equation, or a unit of measurement, or a fundamental physical constant. These honours are the scientific equivalent of having one’s paw-print set into the walk of fame.

And Boltzmann has a constant, k or kB, according to fashion, describing the link between temperature and energy. Scientists use this constant every day making his memory immortal, and raising his image to an almost mystical level

So speaking with his real great grandson was something of a shock! It reminded me that even ‘great’ people are people too, and I was happy to celebrate his birthday (he would have been 170) with my team today.

And we were very fortunate that Tesco had a suitable cake in store – what are the chances of that?

Flooding and Climate Change: What have we learned?

February 17, 2014
The River Thames in flood last weekend. As I write, the water level has called by around 20 centimetres.

The River Thames in flood last weekend. As I write, the water level has fallen by around 20 centimetres. What lessons have we learned?

As the flood waters slowly recede, can I be the first to congratulate the Environment Agency?

We have just experienced the worst sequence of weather events for a few decades or a few centuries. And almost nobody was hurt, and only a few thousand houses were flooded. That has to be a pretty good result.

Although these events cannot in any way be linked to Climate Change, there is still a lesson to be learned in that regard: and that is that we are vulnerable.

If the future climate changed so that such weather was more normal – then we would be have to adapt and there would be real costs (financial and otherwise) involved. And if the weather changed more dramatically, then the consequences could easily be more significant.

Now you may think that following Julia Slingo’s comments to the media that there is a link toClimate Change. So I read the Met Office’s 27 page media briefing on ‘the recent storms’ with interest. It reads like a police report of a pub brawl. But instead of:

  • A hit B because B said’s A’s girlfriend was sleeping with C.
  • C screamed and hit A who then attacked D who fell over and hit the bar.

We have:

  • Excess rain in the tropical Pacific affected stratospheric winds
  • These winds made tropospheric storms across North America move southward drawing air from the warm Atlantic etc. etc.

And then after 26 pages the report concludes

… it is not possible, yet, to give a definitive answer on whether climate change has been a contributor or not. 

So let’s put that particular baby to bed: in 30 years time when we look back we will see whether this event was part of a trend or merely a blip – but at this moment, we just don’t know.

And when in 30 years we look back, what will we say?

  • Will we say ‘Thank you’ to ourselves for considering the  possibility that this could be start of a significant change?
  • Will we be grateful to ourselves for updating our flood defences, and adapting our farming and flooding strategies?
  • Will be glad that the extra money we spent saved lives in the many storms which followed?
  • Or will we regret spending the money because – as things turned out – there were no major floods since.
  • Or will we look back and say ‘Great’ we got away with that – we have had 30 years without flooding?
  • Or will we kick ourselves for not acting when we could have done.

Whatever we want to be thinking in 30 years time, we need to act to achieve it now.

How good are climate models and climate forecasts?

February 12, 2014
Figure 10.1 (b) from the IPCC 5th Assessment Report shows the results of climate calculations ignoring the effect of human-induced climate forcing due mainly to carbon dioxide.

Figure 10.1 (b) from Chapter 10 of the IPCC 5th Assessment Report. The red line shows the results of calculated change in global mean surface temperature ignoring the effect of human-induced climate forcing due mainly to carbon dioxide. The black line shows our observations. We conclude that we cannot understand the Earth;s climate without account for human-induced Climate Change. If only we could go back to the 1960’s and make different choices…

Modelling the interactions of the ocean and atmosphere to predict the future climate of the entire Earth is one of the most breath-taking achievements of modern science. The sheer chutzpah of the endeavour is inspiring.

And much of the debate about the impact of climate change centres on the reliability of these ‘Climate models’. So I read with interest the review of climate models included in Chapter 9 of the 5th Assessment report of the state of the Intergovernmental Panel on Climate Change (IPCC) and enjoyed the presentation at the Royal Meteorological Society meeting last week.

I am not a specialist in this field, but I was impressed by the report, by the talk, and by just how good Climate Models are. The report draws on two ‘Coupled Model Inter-comparison Projects’: CMIP Phase 3 which covers 24 models and CMIP Phase 5 which covers 41 models.

Each model makes predictions for one possible evolution of Earth’s weather and its results are then averaged over time and region to yield Climate estimates.

Each model is fed data on the past state of the climate up until (say) 1900 and then calculations are made in roughly 15-minutes steps to see how the climate evolves as the Earth turns, the Sun shines, Volcanoes erupt, and carbon dioxide levels increase.

We then look back at our actual climate records and see how well each model performed. Of particular interest is the average performance of the models – which represents our collective ‘best estimate’ for what will happen.

What struck me most strongly is that the authors highlight where models get things wrong. This is such an unfashionable writing style one could easily get the sense that none of the climate models are ‘correct’. And of course none of them are perfect. But it is this obsession with error and uncertainty which is a hallmark of a community genuinely concerned with accuracy.

Actually, the models do pretty well. For me the most amazing graph was Figure 9.35 on Page 803. It shows the model’s predictions for the variability of the air temperature above the ocean surface in a particular region of the Pacific Ocean. Most models show a pattern of variability with peaks every 2 to 7 years – similar to the observed variability of El Nino events.

But ‘predicting’ the past is relatively easy because ‘bad’ models can be eliminated.

What about predicting the future? Can we say how reliably the models will predict the future? The authors summarise the state of the art thus (Page 745)

In general, there is no direct means of translating quantitative measures of past performance into confident statements about fidelity of future climate projections.

There has been substantial progress since the AR4 [the 4th Assessment Report in 2007] in the methodology to assess the reliability of a multi-model ensemble, and various approaches to improve the precision of multi-model projections are being explored. However, there is still no universal strategy for weighting the projections from different models based on their historical performance.

The models represent our very best attempt to consider all the physical factors of which we are aware, and to work out what is going to happen. Using multiple models and looking at the extent of agreement and disagreement between them is one way of assessing the likely accuracy of the model predictions.

But the long and the short of this is that ‘we just don’t know’ what will happen in the future.

However this shouldn’t diminish the achievements of understanding that these models embody, even if they prove inaccurate in some predictions. Similarly, it would also be unwise to believe them absolutely, even if they prove accurate.

We are talking about the future, and we need to remind ourselves of this. The results of climate forecasts can guide us, and it would be bonkers to ignore their guidance. But the real challenge is to make policy choices now in the face of the real uncertainty.

The IPCC 5th Assessment Report: The authors speak

February 9, 2014
A slide from the first talk of the Royal Meteorological Society Event.

A slide from the first talk at the Royal Meteorological Society meeting discussing the 5th Assessment Report of the Intergovernmental Panel on Climate Change. Is it really unequivocal?

Last week I attended my first meeting of the Royal Meteorological Society: it was a Wowser!

Many of UK’s leading climate scientists gave 15 minute précis talks describing the key results from the chapters of the IPCC 5th Assessment report on which they were authors.

  • The slides used in the précis talks and audio recordings of each talk can be found here.
  • The chapters of the IPCC assessment report can be found here.

I went with the aim of getting answers to three questions:

  • How good are climate models?
  • What does the data look like on sea level?
  • Why is Antarctic Sea Ice increasing in extent?

I will cover these questions in future articles, but here I would just like to comment on one of the first slides (reproduced above) stating baldy that there was simply no doubt that the Earth’s climate had warmed.

I found this interesting in the of a light of comment by climate skeptic Judith Curry who quotes another web-site stating that ‘Freezing is the new warming

Or try refuting global warming. Temperatures have stopped warming for more than a decade? That’s just a temporary “pause” in the warming that we just know is going to come roaring back any day now. Antarctic ice is growing? That’s actually caused by the melting of ice, don’t you know. A vicious cold snap that sets record low temperatures? That’s just because the North Pole is actually warming. So if the winter is warm, that’s global warming, but if the winter is cold, that’s global warming, too. If sea ice is disappearing, that’s global warming, but if sea ice is increasing, that’s global warming.

Now we can see what they mean when the warmthers say that global warming is supported by an ironclad scientific consensus. The theory is so irrefutable that it’s unfalsifiable!

Which is to say that it has become a cognitive spaghetti bowl full of ad hoc rationalizations, rather than a genuine scientific hypothesis. 

As the meeting progressed I reflected on the possibility that these scientists – myself included – were involved in some kind of collective delusion. Was that really believable?

I decided not, but I thought it was a question worth asking, and answering clearly. So here is the answer.

There are three key facts which are beyond any reasonable doubt.

  1. The concentration of carbon dioxide in the Earth’s atmosphere is increasing.
    • This has been measured directly for more than 50 years and historical values can be inferred from ice cores in Greenland and in Antarctica.
  2. The reason for this increase is our burning of fossil fuel
    • We can detect the isotopic signature of ‘fossil’ carbon and the reduction in oxygen concentration cause by the combustion.
  3. Carbon dioxide increase the ‘radiative forcing’ on the Earth’s climate system.

What is unknown is precisely what the consequences of the warming will be, or how rapidly they will become apparent. The Earth’s climate system is complex, and it does not repond in a simple way.

To use a mechanical analogy, if one pushed a rigid sphere one could predict how it would respond. But if one pushes a spherical jelly, then it will still move, but there will be many wobbles and its precise trajectory is not easily predictable.

So if we look at Curry’s criticisms one by one:

  • Temperatures have stopped warming for more than a decade?
    • A decade is not a long time in Climate Studies, and this just doesn’t mean anything yet. Many other indicators of climate change have continued to change.
  • Antarctic ice is growing?
    • As I mentioned previously – Antarctic Sea Ice is growing slightly. I don’t know why and when I ask specialists I get answers that seem handwaving. However Arctic Sea is shrinking dramatically, and this is well understood and predicted by climate models.
  •  A vicious cold snap that sets record low temperatures?
    • Curry here talks of North America: globally it has not been particularly cold. But one cold winter is weather not climate.

Predicting the future climate of Earth is almost as hard as predicting the weather, and in fact predictions from the 1980s are shaping up pretty well.

So as time moves on, and our understanding of the basic principles that determine climate improves, this only reinforces our understanding that human-kind’s emissions of carbon dioxide are affecting the Climate. There really is no doubt about it.

I was impressed that at the meeting there was complete openness about which data were well-understood, and which models worked well and which worked not so well. Hearing this open discussion is one of the most convincing signs of a research community that was very much focussed on reality, which is never simple.


Thank you to Variable Variability for the quote from Judith Curry’s site.

Time Laboratories

February 5, 2014
TIme Laboratories this way...

Time Laboratories this way…

Occasionally a sign at work makes me look twice. And last Friday as I staggered into work after my talk at Keele University, I came across a sign pointing to ‘Time Laboratories’. It made me smile and so I took the picture above.

The sign was for tours later in the day for distinguished visitors who were celebrating the fact that NPL had been chosen by the European Physical Society as ‘The Birthplace of Atomic Time‘. I gate-crashed the unveiling of the plaque, but didn’t get to go on the tours – work!

Back in the 1960s a scientist (Louis Essen) in a position only a little more senior than my own, worked out how to make a clock that could tick in time with the vibrations of atoms. Humankind’s ability to measure time immediately improved by a factor of nearly 1000.

Even at the time, people understood this was important. It was relatively quickly incorporated into the definition of the unit of time, the second.

This also represented the first realisation of the insight of James Clerk Maxwell in 1870 that we should base our units of measurement on the properties of ‘imperishable’ atoms.

And now in an age of the internet and global positioning systems, atomic time is commonplace and essential. But it is hard to imagine that anyone back in the 1960’s could have foreseen just how-reaching would be the consequences of this measurement innovation.

Personally I draw two lessons from this story. Firstly, I suspect that improvements in measurement capability will rarely go unexploited for long. And secondly, I think we really have no idea what the consequences of a particular measurement exploit will be.

If only we had some kind of ‘time laboratory’ that could allow us to see into the future. In fact it may be that we do have that already – I didn’t get to go on the tour 😦

A scientist walks into a bar…

February 2, 2014
A Scientist walks into a bar...

A scientist walks into a bar…

I like talking about my work and I find it hard to say ‘No’ to an invitation. I also think that talking to the public who pay for my work is a really important thing to do! Consequently, I was out-and-about quite a bit last week, giving talks to the public in Oxford, Kingston and Keele.

The toughest ‘gig’ by far was a Cafe Scientifique event in Kingston, talking about my work making the world’s most accurate thermometer.

Why was it tough? Well normally my talks are accompanied by Powerpoint slides: at the click of a remote control I can summon up photographs, diagrams, animations, songs and words.

And I can have a graphic that reminds the audience what I have said already, and reminds me what I am about say next.

Just standing up in a bar and talking felt like being naked. So I used props as ‘fig-leaves’ – handing around a thermal camera, an infrared thermometer and showing people the how an acoustic thermometer works with 50 metres of yellow tubing.

And I tried to regularly re-cap, and remind the audience and myself what I was trying to say. Hopefully something made sense.

It was a lovely audience: there were university students, and parents and children studying GCSEs; there was Helen Sharman – who eschews celebrity – but who shook my hand and smiled at me which in itself made the evening worthwhile! And there were academics from Kingston university, including a neuro-physiologist who told me about TRPV1 and human perception of temperature.

There were questions about absolute zero and ultra-high temperatures. And basic questions about whether the argon gas I had used in my experiment was composed of molecules or atoms.

I had always thought that the word ‘molecule’ referred to the ‘smallest unit which combines chemically’, and that it could be monatomic, diatomic, triatomic or polyatomic. However, I was told that monatomic molecules were not molecules. Mmmm… I will have to think about this – but it is a reminder to me of the importance of using language clearly and precisely.

By chance my talk two days later was at Keele University in a building named for Sir John Lennard-Jones – who made seminal calculations about  interactions between argon molecules (or should that be atoms?).

The Lennard-Jones Building at Keele University. This is the spiritual home of anyone interested in interactions between argon molecules (or atoms).

The Lennard-Jones Building at Keele University. This is the spiritual home of anyone interested in interactions between argon molecules (or atoms).

Sadly even the ghost of Sir John had left the building as I started my three-hour drive home. But I reflected on his work as I drove. Based on measurements of the properties of argon gas, he was able to predict the properties and crystal structure of solid argon, which even today is pretty cool.


P.S. On the off-chance that anyone will be interested, I will be giving a talk at the Brighton Cafe Scientifique on June 17th 2014.

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