Archive for September, 2012

Denial in Action

September 23, 2012
Interesting Map showing the different 'seas' within the Arctic Ocean. Source NSIDC

Interesting Map showing the different ‘seas’ within the Arctic Ocean. Source NSIDC

The collapse in the extent of the summer minimum of Arctic Sea Ice has been a shock to everyone, but in honesty, not really a surprise. But disappearance of three-quarters-of-a-million square kilometres of sea ice seemed to be such a dramatic change that I was sure that Climate Change ‘sceptics’ would be holding up their hands and saying simply ‘I was wrong’. So I headed over to the Sea Ice Update pages of Antony Watts ‘Watts Up’ site to witness their surrender.

But far from admitting that their world view was flawed, the ‘Climate Sceptics’ were responding in a manner which would be hilarious if it were not so tragic. The discussion is a classic example of a group unable to ‘distinguish the forest from the trees’. The discussion is focussed on individual facts (the trees) which are discussed in detail and critically examined. But they denounce anyone who raises the wider context of the facts (the forest) i.e. the only theory which predicted sea-ice melting. Indeed our concerns that this might happen are the very reason that the sea-ice data exists.

The page begins with a section noting that:

…there are some quite large Sea Surface Temperature Anomalies in the Arctic at present [up to 7 °C]. They appear to centered in four primary areas, the coasts of the Beaufort, Laptev and Kara Seas, as well as the middle of Baffin Bay. There are a multitude of potential explanations for these anomalies, let’s take them individually

We then get the individual potential explanations which I will summarise:

  1. Could be due to the low sea ice extent which means areas previously covered with ice are now exposed.
  2. Could be due to an ‘unusually strong storm’ which occurred early in August which could have broken up the ice cover.
  3. Could be Albedo Feedback – the replacement of reflective sea ice with dark ocean – likely to be a factor.
  4. Could be anthropogenically-warmed river discharges – quite likely a factor in some areas.
  5. Could be Northern Polar Lower Troposphere Anomalies – basically the air temperature has warmed over the decades, but enough for the trend to explain the sea surface temperature anomalies.
  6. Could be Tundra Vegetation Feedback – where the sea ice has retreated plants have begun to grow, changing surface albedo.

I have summarised these explanations but each one is discussed in detail. The discussions then cover other possible explanations:

  • Arctic Drilling
  • Undersea Volcanos
  • Soot from Chinese Coal Power Stations
  • The effect of the North Atlantic Oscillation – a persistent weather pattern with two distinct stable states.
  • Absorption of Energy from Geomagnetic Storms
  • Increased use of icebreakers and even tourist boats.
  • There has been no extra melting – just dispersal of sea ice into smaller pieces which are not counted as contiguous sea ice.

All these are discussed intelligently, helpfully and politely. It is an admirable example of a community of interested people discussing a topic. But when someone suggests:

There’s the increased release of anthropogenic greenhouse gases, such as CO2.

they are quickly told…

OK, you made a conjecture. Now, show a direct connection between Arctic ice melt and anthropogenic CO2, per the scientific method: testable, and using raw data. Otherwise, you have just expressed an opinion, nothing more.

In short – we don’t want to know about this.

In fact Climate models – our way of taking account of as many factors as we can think of – predicted long ago that Arctic warming would result from CO2 emissions. And Arctic warming can be reasonably expected to thin the ice sheet over the Arctic Ocean, which will then break up when there is a storm. All of the factors mentioned above may be proximate causes of the ice break up and enhanced sea-surface temperatures. But in fact the ultimate cause is in all probability the emission of greenhouse gases.

What we learn is that this group of well-meaning, interested and intelligent people simply rejected the most likely cause of this astonishing phenomenon. It caused me to wonder, if  there were any event which would cause these people – not perhaps to change their minds – but to perhaps shift their opinion slightly. To consider that perhaps all the world’s experts in Climate studies might just have a point worth considering?

Arctic Sea Ice 2012

September 10, 2012
Sea Ice Summer 2012

Daily satellite records of the extent of Arctic Sea Ice since 1980. The regular pattern of of melting and re-freezing appears to have been significantly disturbed in recent years. Click for a larger version. Data from NSIDC – see text for links.

I have returned from my holidays and the children are back at school. So I guess summer is over and it’s time for my annual check on how the Arctic sea ice is doing. … What?

The summer minimum of Arctic sea-ice extent will probably be reached in the next couple of weeks but already the previous minimum sea-ice extent has been undercut by more than a half-a-million square kilometres. Currently there are only around 3.5 million square kilometres of sea ice. The previous minimum value in 2007 was 4.2 million square kilometres. In the 1980’s – when I was twenty-something and unconcerned about Climate Change – a more typical figure would have been 7 million square kilometres of sea ice.

The graph at the head of the page shows the data which is collated from spreadsheets available here, here (old data) and here (new data). A multitude of graphics are available at the US Snow and Ice Data Center.

The BBC has reported this story pretty thoroughly and even The Register is shocked! But I am almost lost for words.

  • First we need to remind ourselves that nobody – and I mean nobody – knows what is going to happen next. However it looks like the people modelling the volume of arctic sea ice have their models just about right. Even while the sea-ice area was relatively stable, the ice thickness was probably declining. Once a minimum thickness is reached, the coherent ice sheet is broken apart by weather. The reflectivity of the surface then changes and much more solar radiation is absorbed. It is interesting to note that in contrast with the recent changes in summer sea-ice, the sea-ice winter maximum appears be only declining rather slowly.
  • If the volumetric modelling is correct, then as I mentioned previously, over the next few years – and I mean years and  not decades – summer ice in the Arctic will reduce in extent dramatically. It is quite plausible that even by 2020 we could have a few days each year in which there is no coherent ice sheet in the Arctic.
  • Once the sea-ice melts in summer then  each year the number of days that the ice melts will increase and summer ocean surface temperatures will begin to rise above zero. It is not clear that we will ever reach a situation in which sea ice will not form in winter – but it is possible. Remember that summer in the Arctic is more intense than anywhere else on Earth. It is a shocking fact that during each day of the Arctic summer, more solar energy falls on each square metre of sea or ground in the Arctic than ever falls on a square metre of ground in the tropics or deserts.

In my opinion this data speaks more eloquently than either myself, or reams of scientific papers discussing global temperature. This data speaks eloquently and it is saying very clearly – “something dramatic is happening in the Arctic: be concerned.”

GCSEs: What does an ‘A’ grade mean?

September 5, 2012
Chart showing the percentage of students taking each subject that achieved an A or A* grade. Click for a larger version. Notice that only 3.1% of students achieved an A* in 'Home Economics' while 5.5% of students achieved an A* in 'Mathematics'. What does that mean?

Chart showing the percentage of students taking a subject at GCSE in 2012 that achieved an A or A* grade. Click for a larger version. Notice that only 3.1% of students achieved an A* in ‘Home Economics’ while 5.5% of students achieved an A* in ‘Mathematics’. What does that mean?

The percentage of students being awarded A and A* grades at GCSE has fallen for the first time in 25 years. In my opinion this is a good thing, but as the furore over the re-alignment of grades for the English GCSEs makes clear, it heralds several years of pain as exam marking slowly returns to reality.

What these painful events demonstrate is that we need to be clear about what a particular mark signifies. At the moment this is almost impossible to guess.

The chart at the top of the page  shows the percentage of the cohort that take an exam in various subjects that get an A or A*. The Guardian DATA blog has discussed the data and the data itself can be found here (as a Google Docs spreadsheet). It is worth clicking on the figure at the top of the page to enlarge it, but in case you are too busy, let me highlight two of the odd statistics it shows up.

  • Only 3.1% of students achieved an A* in Home Economics while 5.5% of students achieved an A* in Mathematics.

Does that mean that an A* in Home Economics is harder to get than an A* in Mathematics?

  • 95.5% of students achieved an A or A* in Classical Subjects (i.e. Greek or Latin)

Does that mean that Classical Subjects are easy?

In each case the answer is confusing and all that the designations indicate is that for each subject A* is better than A, A is better than B etc.. I trust my readers to appreciate the subtlety of interpretation required to understand the data, But is clear from the spread that there is neither an absolute nor a relative meaning to the designation.

We need to recognise that exams perform two quite distinct functions. The first is to discriminate amongst students, and the second is to determine who has reached an acceptable level of education in a particular topic. The first is easy, and ‘when I was a lad’ was all that was used. The second is harder, and its mis-implementation has lead to rampant grade inflation over the last 25 years.

The solution is to have clear definitions of what the grades mean. Allow me to suggest the following:

  • A*: the top 5% of the cohort taking the exam.
  • A: the next 10% of the cohort
  • B: Good pass:
  • C: Pass

Grades A and A* would be inflation-proof measures that allowed employers and colleges to discriminate amongst the students. Grades B and C would allow employers and colleges to select people that had a good or basic understanding of a subject. This structure combines the two functions of an exam.

This year my eldest son took GCSE exams and he did well. But as his results were announced I was reminded of the personal dramas of each of the half-a-million candidates. The chaos of the current scheme undermines the achievements of many students while failing to highlight areas where as a nation we need to improve. We owe it to ourselves and our children to make the results of the students work mean something that will not change from year to year.

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