Dr. Garth Paltridge on JudithCurry.com: Reluctance of IPCC to reduce confidence levels in light of hiatus and misunderstood mechanisms shows a lack of scientific skepticism. [For fact checking & general commentary]
Summary of initial comments in the Scientists’ Comment Thread [updated 4/28/14]:
Dr. Andreas Schmittner: “G.Paltridge claims that scientists could not exclude the possibility that the surface warming observed over the last 50 years was due to fluctuations in ocean currents. This is extremely unlikely given the observed [changes]. The claim of “no significant warming over the most recent 15-or-so yrs” is also wrong: “[O]cean heat content shows uninterrupted warming… See Global Ocean Heat Content 1955 to present (0-2000m) [here].”
Dr. Michael Tobis: “Many half-truths and frank misinterpretations here. […] It may or may not be useful to potential audiences to have another place where reason and evidence is placed head to head against posturing and rhetoric. But such a thing is not useful or appealing to scientists.”
Dr. Judith Curry: “G.Paltridge is a distinguished Australian atmospheric physicist. I don’t find much to disagree with in [this] essay. I would hope that other participants who ‘don’t like’ this essay will critique the disputed points and provide evidence refuting his arguments. […] The uncertainties in ocean heat content below 700 m are very substantial, see here.”
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The following excerpts are from a recent guest post on JudithCurry.com, titled “The Fundamental Uncertainties of Climate Change,” by Dr. Garth Paltridge. (Click on the link for the full article on JudithCurry.com.)
The Fundamental Uncertainties of Climate Change, by Garth Paltridge
There is more than enough uncertainty about the forecasting of climate to allow normal human beings to be at least reasonably hopeful that global warming might not be nearly as bad as is currently touted. Climate scientists, and indeed scientists in general, are not so lucky. They have a lot to lose if time should prove them wrong.
The World Meteorological Organization of the United Nations took its first steps towards establishing the World Climate Program in the early nineteen-seventies. Among other things it held an international conference in Stockholm to define the main scientific problems to be solved before reliable climate forecasting could be possible. The conference […] focused on two [problems]. The first concerned an inability to simulate the amount and character of clouds in the atmosphere. Clouds are important because they govern the balance between solar heating and infrared cooling of the planet, and thereby are a control of Earth’s temperature. The second concerned an inability to forecast the behavior of oceans. Oceans are important because they are the main reservoirs of heat in the climate system. They have internal, more-or-less random, fluctuations on all sorts of time-scales ranging from years through to centuries. These fluctuations cause changes in ocean surface temperature that in turn affect Earth’s overall climate.
The situation hasn’t changed all that much in the decades since the conference. Many of the problems of simulating the behavior of clouds and oceans are still there (along with lots of other problems of lesser moment) and for many of the same reasons as were appreciated at the time. Perhaps the most significant is that climate models must do their calculations at each point of an imaginary grid of points spread evenly around the world at various heights in the atmosphere and depths in the ocean. The calculations are done every hour or so of model time as the model steps forward into its theoretical future. Problems arise because practical constraints on the size of computers ensure that the horizontal distance between model grid-points may be as much as a degree or two of latitude or longitude – that is to say, a distance of many tens of kilometres.
That sort of distance is much larger than the size of a typical piece of cloud. As a consequence, simulation of clouds requires a fair amount of inspired guesswork as to what might be a suitable average of whatever is going on between the grid-points of the model. Even if experimental observations suggest that the models get the averages roughly right for a short-term forecast, there is no guarantee they will get them right for atmospheric conditions several decades into the future. Among other problems, small errors in the numerical modelling of complex processes have a nasty habit of accumulating with time.
Again because of this grid-point business, oceanic fluctuations and eddies smaller than the distance between the grid-points of a model are unknown to that model. This would not be a problem except that eddies in turbulent fluids can grow larger and larger. A small random eddy in the real ocean can grow and appear out of nowhere as far as a forecasting model is concerned, and make something of a dog’s breakfast of the forecast from that time on.
All of the above is background to one of the great mysteries of the climate change issue. Virtually all the scientists directly involved in climate prediction are aware of the enormous problems and uncertainties still associated with their product. How then is it that those of them involved in the latest report of the Intergovernmental Panel on Climate Change (the IPCC) can put their hands on their hearts and maintain there is a 95% probability that human emissions of carbon dioxide have caused most of the global warming that has occurred over the last several decades?
Bear in mind that the representation of clouds in climate models (and of the water vapour which is intimately involved with cloud formation) is such as to amplify the forecast warming from increasing atmospheric carbon dioxide – on average over most of the models by a factor of about 3. In other words, two-thirds of the forecast rise in temperature derives from this particular model characteristic. Despite what the models are telling us – and perhaps because it is models that are telling us – no scientist close to the problem and in his right mind, when asked the specific question, would say that he is 95% sure that the effect of clouds is to amplify rather than to reduce the warming effect of increasing carbon dioxide. If he is not sure that clouds amplify global warming, he cannot be sure that most of the global warming is a result of increasing carbon dioxide.
Bear in mind too that no scientist close to the problem and in his right mind, when asked the specific question, would say there is only a very small possibility (i.e. less than 5%) that internal ocean behaviour could be a major cause of the warming over the past half-century. He would be particularly careful not to make such a statement now that there has been no significant warming over the most recent fifteen-or-so years. In the mad scurry to find reasons for the pause, and to find reasons for an obvious failure of the models to simulate the pause, suddenly we are hearing that perhaps the heat of global warming is being “hidden” in the deep ocean. In other words we are being told that some internal oceanic fluctuation may have reduced the upward trend in global temperature. It is therefore more than a little strange that we are not hearing from the IPCC (or at any rate not hearing very loudly) that some natural internal fluctuation of the system may have given rise to most of the earlier upward trend.
In the light of all this, we have at least to consider the possibility that the scientific establishment behind the global warming issue has been drawn into the trap of seriously overstating the climate problem – or, what is much the same thing, of seriously understating the uncertainties associated with the climate problem – in its effort to promote the cause. It is a particularly nasty trap in the context of science, because it risks destroying, perhaps for centuries to come, the unique and hard-won reputation for honesty which is the basis of society’s respect for scientific endeavour. Trading reputational capital for short-term political gain isn’t the most sensible way of going about things.
The trap was set in the late seventies or thereabouts when the environmental movement first realised that doing something about global warming would play to quite a number of its social agendas. At much the same time, it became accepted wisdom around the corridors of power that government-funded scientists (i.e. most scientists) should be required to obtain a goodly fraction of their funds and salaries from external sources – external anyway to their own particular organization.
The trap was fully sprung when many of the world’s major national academies of science (the Royal Society in the UK, the National Academy of Sciences in the US, the Australian Academy of Science, and so on) persuaded themselves to issue reports giving support to the conclusions of the IPCC. The reports were touted as national assessments that were supposedly independent of the IPCC and of each other, but of necessity were compiled with the assistance of, and in some cases at the behest of, many of the scientists involved in the IPCC international machinations. In effect, the academies, which are the most prestigious of the institutions of science, formally nailed their colours to the mast of the politically correct.
Since that time in 2010-11 or thereabouts, there has been no comfortable way for the scientific community to raise the spectre of serious uncertainty about the forecasts of climatic disaster.
What has happened to the scepticism that is supposedly the lifeblood of scientific enquiry?
The answer probably gets back to the uncertainty of it all. The chances of proving – repeat proving – that change of climate over the next century will be large enough to be disastrous are virtually nil. For the same reason, the chances of a climate sceptic, or anyone else for that matter, proving the disaster theory to be oversold are also virtually nil. To that extent there is a level playing field for the two sides of the argument. The problem is that climate research necessarily involves enormous resources, and is a game for institutions and organizations. Scepticism is an occupation for individuals. Things being as they are in the climate change arena, scepticism by an individual within the system can be fairly career limiting. In any event, most individual scientists have a conscience, and are reluctant to put their head above the public parapet in order to propound a view of things that may be inherently unprovable.
In short, there is more than enough uncertainty about the forecasting of climate to allow normal human beings to be at least reasonably hopeful that global warming might not be nearly as bad as is currently touted. Climate scientists, and indeed scientists in general, are not so lucky. They have a lot to lose if time should prove them wrong.
Dr. Garth Paltridge is a retired atmospheric physicist from Australia. He is an emeritus professor and honorary research fellow at the University of Tasmania, visiting fellow at the Australian National University Research School of Biology, and fellow of the Australian Academy of Science. The full transcript of this post can be found at JudithCurry.com (click on link). This piece was originally published in Quadrant magazine, Jan-Feb 2014, and is accessible via Quadrant On Line.
Administrator’s note: The summary of the initial comments by the CCNF scientists at the top was added to this post on 4/28/14. This is the new format for the ‘Climate Change in the Media — Commentary and fact checking…’ section.