Posts Tagged ‘Sceptics’

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?

What Climate Sceptics are Sceptical About: Part 3

June 4, 2012

Following my article in Chemical Industry on climate change, I have received another long missive. Whereas my first correspondent saw the entire issue as being essentially political, and my second correspondent required an answer to a technical question, my third correspondent has brought together four arguments which they feel together make a rounded case for a sceptical position. But four weak arguments are still just four weak arguments whether taken collectively or individually. Summarising the arguments are:

  1. James Lovelock says ‘everyone got it wrong’
  2. CO2 by itself can never cause more than 0.3 °C of Global Warming
  3. There is correlation between CO2 concentration and Global Mean Temperature
  4. Global Mean Temperature is no longer rising.

Let’s take a look at them one by one.

1. James Lovelock is not a climate scientist of any note, and I really don’t think that his personal opinions count for anything. I don’t believe things just because other people say they believe things, and neither should anyone else. I listen to people, reflect on what I have heard, and consider how it affects my own views. Lovelock has changed his mind, ‘Great’. When a person has changed their mind – that means they have learned something’. I discussed his comments on my blog here.

2. Regarding the warming one might expect from CO2, I do not recognise the figure of 0.3 °C. The idea of a maximum limiting amount of warming is based on imagining that when the atmospheric CO2 absorbs all the infrared light emitted directly from the Earth’s surface then the warming effect is saturated. That is not how it works. This post describes the process more fully, and one expects a pretty much linear increase in climate forcing with CO2 concentration.

As an analogy consider a torch shining upwards through a tank containing a coloured solution. How is the radiation which emerges from the top affected by the concentration of the solution?

Light through a tank

An analogy to the absorption of infrared light in the atmosphere. Light is shone through a tank containing a coloured solution. In the left case, the solution is weak and the light travels straight through, and a weakened beam emerges at the end of the tank. In the right case, the concentration of the solution has been increased so that all the light is absorbed. No more light can be absorbed no matter how strong the solution. This analogy is of limited value when considering the transmission of infrared light through the atmosphere. When infrared light is absorbed in the atmosphere, the Earth begins to warm until exactly the same amount of infrared light leaves the atmosphere as did before. This is equivalent to increasing the brightness of the torch until the same amount of light leaves the far side of the tank as did in the left-hand case above.

If the solution is dense enough, then all the light will be absorbed, and this is the basis of the point being made. But in the case of the Earth, when all the infrared light is absorbed it creates a warming (which is equivalent to turning up the brightness of the torch) until exactly the same amount of light emerges as did before the change in the solution. So increasing the carbon dioxide concentration does temporarily reduce the amount of infrared light that leaves the atmosphere. But this then warms the Earth and the climate system only attains equilibrium when the radiated infrared light leaving the top of the atmosphere returns to its previous value.

3. The correlation between CO2 and global mean temperature is astonishing. But in order to see this correlation it is necessary for the global climate system to be relatively stable, which takes decades to centuries. The figure below shows the data over the last 400,000 years and there is a strong correlation between global mean temperature (inferred from the the relative amounts of oxygen isotopes found in water in ice cores) and atmospheric CO2 concentration (deduced form the residual concentration of CO2 in bubbles in the ice). Very roughly 100 ppm CO2 corresponds to around 10 °C of warming – a truly terrifying statistic if it holds for warming as well as cooling. Looking over a shorter time-scale is frankly meaningless.

ICe Core Data

Graph of atmospheric concentration of CO2 (Green graph) and Global Mean temperature (Blue graph), deduced from the Vostok, Antarctica ice core as reported by Petit et al., 1999.The data are plotted at ‘thousands of years before the present, so ‘now’ is on the left of the graphs and the past runs over to the right. The main oscillations arise from changes in Earth’s orbital eccentricity, tilt, and precession called Milankovitch cycles. The correlation between CO2 concentration and global mean temperature is very clear. Picture taken from wikipedia, but other versions are available.

A good deal has been made in sceptic circles as to whether the CO2 concentration rise preceded the temperature rise (and may thus be said to ’caused’ or contributed to it) or followed the temperature rise (in which case sceptics assert that it cannot have ’caused’ or contributed to the temperature rise). Detailed analysis indicates that changes in CO2 concentration usually follow temperature changes, but that they sometimes precede them. The reason that the link works in both directions is because increases in temperature cause increases in atmospheric CO2 concentration by enhancing the release of dissolved CO2 from the oceans. And increases in atmospheric CO2 concentration then cause further rises in temperature because CO2 is an infrared active gas. In short, the quantities are highly-correlated.

4. Has the warming stopped? The high sceptical Berkley group discussed the possibility  under the heading ‘Has the warming stopped’ in this pdf slide presentation. It could be that for some reason this graph has peaked and that in the future it will stabilise or fall. Time will tell, but the trend looks quite clear.

Annualised data for the air temperature above the land surface of the Earth. Do you think this shows a graph in which the warming trend has stopped. Data From Berkeley Earth Group

Annualised data for the air temperature above the land surface of the Earth. Do you think this shows a graph in which the warming trend has stopped? Data From Berkeley Earth Group

The temperature oscillations on the above graph arise from a number of oscillations in the global climate system, most notably the El Niño-La Niña cycle (called ENSO – El Niño Southern Oscillation), the Atlantic Multi-decadal Oscillation (AMO),  North Atlantic Oscillation (NAO) and a Pacific Decadal Oscillation (PDO). The teams take these oscillations out of the data in order to reveal the underlying trend. The correlations of the data with 4 separate indicices of the largest climate system oscillations are shown below. Notice in the top-left graph that the correlation coefficient for the AMO reaches 0.65 with zero lag. In other words the strength of the AMO directly affects the average temperature above the land surface of the Earth – or at least it has done for the last 62 years.

Berkeley Correlations

Correlations between the air temperature above the land surface of the Earth and 4 different indicators of climate oscillations. These oscillations are removed from the data to reveal the underlying trend. The oscillations have periods of a few years to around a decade. Data From Berkeley Earth Group

Saying that the above data shows that the temperature rise has stopped is liking asking someone if a car indicator light is working and receiving the answer “No…. Oh, Yes it is!……Oh, No, now it isn’t…”

The final argument of my third correspondent was that taking action to reduce emissions would damage our economy. This is a red herring. First we need to be as clear as we can be about what is happening. Although we still don’t understand every single aspect of the effect of the CO2, we would expect effects something like what we observe. But this doesn’t mean that we all have to agree on what to do. Some people think that we should halt emissions in a way which devastate the economy, and others think we should just enjoy the benefits of burning fossil fuels and blow the consequences.

As the science becomes clearer year on year, the contrasts between different policy choices should become clearer too. But it is important not to conflate scepticism about the science, with reluctance to take action.


Global Warming sceptics lose the plot!

February 8, 2012
BEST T Estimate detail

The Air Temperature above the Land Surface of the Earth (1990 -2010) according to the Berkeley Earth Science Group. The data shown are running annual averages of 12 months data (the 'noisy' graph) and running averages of 10 years of data (the smooth graph). What do you think? Is the Land Surface Temperature of the Earth rising?

I hesitate to criticise other scientists: data is often complex and perspectives differ. When it comes to the issue of Global Warming, data is amazingly complex and perspectives differ radically. But I have reached my limit!

A recent opinion piece in the Wall Street Journal by high profile scientists says – summarising – that there is ‘no cause for panic’. The associated WSJ video coverage refers to Global Warming as a ‘hoax’. The comments on the video show utterly irrelevant pictures of snow ploughs!

Friends, colleagues, readers: this is complete nonsense. I don’t want to go on and on about this but the issue is actually breathtakingly simple:

  • Human beings are putting colossal amounts of carbon dioxide into the atmosphere: 30 billion tonnes (-ish) every year. This is roughly 1% of the amount carbon dioxide in the atmosphere.
  • Carbon dioxide absorbs infra-red radiation and is a small part of the greenhouse gas cocktail that warms the Earth by roughly 33 ºC.
  • It would be utterly astonishing if this extra carbon dioxide had no effect – in fact – it is just inconceivable! So the question is: “What effect is it having?”

This is not a right-wing versus left-wing issue: the Financial Times is convinced about the reality of global warming. This a facing-up-to-reality versus not-facing-up-to-reality issue. The scientists are right that ‘panic’ is inappropriate because ‘panic doesn’t help. But everyone should be concerned about this issue. And in my opinion, very concerned.

The Air Temperature above the Land Surface of the Earth according to the Berkeley Earth Science Group. The data shown are running annual averages of 12 months data (the 'noisy' graph) and running averages of 10 years of data (the smooth graph). What do you think? Is the Land Surface Temperature of the Earth rising?

The Air Temperature above the Land Surface of the Earth (1800 -2010) according to the Berkeley Earth Science Group. The data shown are running annual averages of 12 months data (the 'noisy' graph) and running averages of 10 years of data (the smooth graph). What do you think? Is the Land Surface Temperature of the Earth rising?


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