# Is global warming falsifiable? **URL:** \ **Category:** Great Debates\ **Created:** [May 6, 2014, 7:30am UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786 "2014-05-06T07:30:04Z")\ **Posts on this page:** 5\ **Page:** 38
**Author:** ![Sam\_Stone](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Sam\_Stone](https://boards.straightdope.com/u/Sam_Stone)\ **Post date:** [January 11, 2015, 12:02am UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/742 "2015-01-11T00:02:51Z")
Once again, we skirt around the real issues by nitpicking a small change in slope of a very noisy dataset - one in which moving the starting point by a single year can have a drastic effect on the trend. We also muddy the issue by coming up with ‘sound-bite’ arguments or by latching onto non-scientific arguments if they happen to support ‘our’ side while heaping scorn on the opposition when they do the same. For example, it’s common to hear the ‘consensus’ community trumpet stats like, “X of Y hottest years happened in the last decade! That proves it!”. But of course, we all agree that the earth is warming overall, and has been for a long time (long before greenhouse gases would have been a major factor). So even if the warming was just the natural warming you’d expect at this point in the intra-glacial phase, you would still expect each decade to set new records for temperature. It tell us nothing whatsoever as to whether humans are causing global warming. And of course, making the leap from ‘global warming is happening’ to assuming that the only proper response is to tax and otherwise curtail energy is not warranted at all. There are plenty of scenarios under which it’s perfectly reasonably to argue that global warming is happening, and humans are helping to cause it, yet the proper response is to do nothing. Yet the global warming activists act as if it’s a binary choice - if global warming is real, you must do the things we advocate in order to save the planet. They simply do not want to defend those policy proposals - they would rather act as if they are the automatic choice once we assume that global warming is happening. Finally, I still have a real problem with global warming models, for the following reasons: - They assume that we understand the major carbon sources and sinks and the feedbacks that predominate. And yet, almost daily we read about new research that has massive implications for our understanding of climate and the carbon cycle. Usually, as our understanding of a system matures, new discoveries happen on the margins. When new discoveries are being made that have major impacts on core understanding, you know there are still a lot more out there to be discovered. The ‘unknown unknowns’ become the dominant factor. This is especially true in complex adaptive systems (see below). Also, this type of uncertainty is not really captured by the IPCC. The uncertainty they focus on is in the known effects and their amplitude. Systemic uncertainty is another breed of cat. - The models are ‘tuned’ based on past data, and the predictive nature of ‘tuned’ models is highly suspect. - The past predictive track record of these models is not very good - especially outside the region containing the data used to tune the models in the first place. The test for these models is often done by sequestering some of the climate data, using the rest of the data to build the model, then see if the model predicts the data it never ‘saw’. That’s a valid approach in some cases, but in a complex adaptive system it just means that you were able to predict the output of the system when it was in a past, known state. Or in the case of a highly tuned model, you may just be engaged in an exercise of curve fitting by adding terms and fudge factors. Since the nature of a complex adaptive system changes in unpredictable and unknown ways, this isn’t much help for predicting future responses. Ask the Keynesian economists who predicted a massive recession in the U.S. at the end of WWII, or who said that having inflation and high unemployment at the same time was impossible. Or, ask the economists on the right who said that all the quantitative easing in the last decade would result in high inflation. Both used similar models (general equilibrium macro models) to make these predictions. Models that seemed to have predictive ability when applied to the past. Both were spectacularly wrong. - They assume a certainty about climate responses to inputs that are unwarranted, given that climate is a complex adaptive system and our attempts to predict the behaviour of such systems has been pretty dismal. Consider the characteristics of complex adaptive systems: They are sensitive to tiny changes in initial conditions, they have stochastic elements which means their behaviour is not conventionally predictable, and their behavior is dominated by fat-tailed events and various feedbacks. Our attempts to model these systems in macroeconomics, ecology, the immune system, and climate have shown dismal results to date. Economists cannot predict GDP growth even a year in advance with any accuracy better than a simple model that assumes next year’s GDP will be the same as this year’s. It’s funny that the same environmentalists who totally buy into complex systems theory when it comes to ecosystems completely reject the same theory when it comes to climate models. The Gaia hypothesis and the precautionary principle come straight out of early work in complex systems. Environmentalists glommed onto it because it seemed like a strong argument for not trying to control or interfere with nature. But the same logic applies to the economy and to climate, and there because the conclusions favor their ‘opponent’s’ arguments, the left simply ignores it. ---
**Author:** ![Sam\_Stone](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Sam\_Stone](https://boards.straightdope.com/u/Sam_Stone)\ **Post date:** [January 11, 2015, 12:11am UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/743 "2015-01-11T00:11:52Z")
> [@GIGObuster](#): > > And that was done, the dismissal came after the explanation I cited, and it also comes after hundreds of examples of terrible and bad researchers whose trash is allowed to remain in the blog. I wasn’t responding to you, actually. I was responding to the comments that simply cast doubt on WWUT as a ‘denialist rag’ with the implication that anything quoted from there should be ignored. Do you ignore everything the Lancet puts out because they’ve been caught releasing some very obviously bad papers? [quote] > [@](#): > > That is… not relevant, what the article reports is a cherry pick of the past recent observed data, this is not coming from a model but actual data. I wasn’t making a specific case against a specific article. I’m just pointing out that the proper way to think about the problem is to consider uncertainties on both sides, which implies a Bayesian approach rather than assuming that the models are the null hypothesis and therefore correct until opponents can ‘prove’ that AGW is not happening. One other nitpick - rather than arguing whether or not warming has ‘stopped’, the real argument should be based on how well the observations are tracking predictions. I wouldn’t expect the globe to cool regardless of whether man was influencing it or not, so the fact that it isn’t has nothing to do with the subject. So there’s foolishness on both sides. ---
**Author:** ![Sam\_Stone](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Sam\_Stone](https://boards.straightdope.com/u/Sam_Stone)\ **Post date:** [January 11, 2015, 12:14am UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/744 "2015-01-11T00:14:14Z")
As an example of some recent information that seems very important on both sides: [NASA Finds Good News on Forests and Carbon Dioxide](http://www.nasa.gov/jpl/nasa-finds-good-news-on-forests-and-carbon-dioxide/#.VLGxhyvF98F) > [@](#): > > A new NASA-led study shows that tropical forests may be absorbing far more carbon dioxide than many scientists thought, in response to rising atmospheric levels of the greenhouse gas. The study estimates that tropical forests absorb 1.4 billion metric tons of carbon dioxide out of a total global absorption of 2.5 billion – more than is absorbed by forests in Canada, Siberia and other northern regions, called boreal forests. In short, it has been thought that tropical rainforests were not as large a contributor to carbon sequestration, and that the “CO2 fertilization effect” (plants grow faster when they get more CO2) was much smaller. Plants also grow faster when it’s warmer, and the tropics will see the biggest heating effects from global warming. So, if northerm boreal forests are proportionately larger in terms of overall carbon sequestration, this would be a diminishing negative feedback, as the boreal forests are at risk if the planet warms up, and it was expected that the ability of the earth’s greenery to absorb and sequester carbon would get worse as the planet warms. But if the tropical rainforests absorb a higher percentage than previously thought, this is has huge implications for the earth’s future ability to sequester carbon. This is not a small effect, either. The paper finds that the tropical rainforests absorb 1.4 billion metric tons of CO2 per year. That’s a carbon sink equal to about 20% of ALL of the U.S.'s annual carbon output. But more to the point, the models that assume that carbon uptake is going to decline as boreal forests absorb less over time are wrong, and the effect is not small. This is just one paper, of course. Other papers may find other climate feedbacks, both positive and negative. Another example is [this recent paper](http://www.astrobio.net/news-exclusive/scientists-detect-evidence-oceans-worth-water-earths-mantle/) describing the discovery of more water deep underground than exists in all of our oceans. If our ocean levels are determined in part by that deep aquifer, it casts all kinds of doubt on models of sea level rise. It may be that sea levels are determined by an equilibrium between the surface ocean pressure and pressure in the transition zone where all this saturated H20 appears to be. But again, it’s one paper and we have no idea whether that water is connected to the surface at all. The point is that we have just recently discovered another uncertainty about part of the overall climate model. ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [January 11, 2015, 12:22am UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/745 "2015-01-11T00:22:26Z")
And that long tirade only shows that you are not investigating or noticing that a lot of your points are based on hoey from denier groups. [QUOTE=Sam Stone] - The models are ‘tuned’ based on past data, and the predictive nature of ‘tuned’ models is highly suspect. [/QUOTE] > **[Why trust climate models? It’s a matter of simple science](https://arstechnica.com/science/2013/09/why-trust-climate-models-its-a-matter-of-simple-science/)** > > How climate scientists test, test again, and use their simulation tools. > [@](#): > > One surprisingly common misconception about climate models is that they’re just exercises in curve-fitting. The global average temperature record is fed into the model, which matches that trend and spits out a simulation just like it. In this (mistaken) view, having a model that compares well with reality is a necessary outcome of the process. This doesn’t demonstrate that climate models can be trusted to usefully project future trends, but this line of thinking is mistaken for several reasons. > > There’s obviously more to a climate model than a graph of global average temperature. Some parameterizations—those stand-ins for processes that occur at scales finer than a grid cell—are tuned to match observations. After all, they are attempts to describe a process in terms of its large-scale results. But successful parameterizations aren’t used as a gauge of how well the model is reproducing reality. “Obviously, since these factors are tuned for, they don’t count as a model success. However, the model evaluations span a much wider and deeper set of observations, and when you do historical or paleoclimate simulations, none of the data you are interested in has been tuned for,” Schmidt told Ars. [QUOTE=Sam Stone] - The past predictive track record of these models is not very good - especially outside the region containing the data used to tune the models in the first place. [/QUOTE] > **[How reliable are climate models?](https://skepticalscience.com/climate-models-intermediate.htm)** > > \While there are uncertainties with climate models, they successfully reproduce the past and have made predictions that have been subsequently confirmed by observations.\ > [@](#): > > While there are uncertainties with climate models, they successfully reproduce the past and have made predictions that have been subsequently confirmed by observations. > [@](#): > > A paper led by James Risbey (2014) in Nature Climate Change takes a clever approach to evaluating how accurate climate model temperature predictions have been while getting around the noise caused by natural cycles. The authors used a large set of simulations from 18 different climate models (from CMIP5). They looked at each 15-year period since the 1950s, and compared how accurately each model simulation had represented El Niño and La Niña conditions during those 15 years, using the trends in what’s known as the Niño3.4 index. > > Each individual climate model run has a random representation of these natural ocean cycles, so for every 15-year period, some of those simulations will have accurately represented the actual El Niño conditions just by chance. The study authors compared the simulations that were correctly synchronized with the ocean cycles (blue data in the left frame below) and the most out-of-sync (grey data in the right frame) to the observed global surface temperature changes (red) for each 15-year period. > [@](#): > > The authors conclude, > > ``` > When the phase of natural variability is taken into account, the model 15-year warming trends in CMIP5 projections well estimate the observed trends for all 15-year periods over the past half-century. > > ``` As for the rest of your tirade that also implies that this is a leftist matter (ignoring all the conservaty scientists that are telling you how ignorant that is) You need to realize once and for all that while there are indeed complex sistems the reality is that a lot of effort has been geared to understand and make better models, and this is indeed a very accepted tool to use in science. > **[Why trust climate models? It’s a matter of simple science](https://arstechnica.com/science/2013/09/why-trust-climate-models-its-a-matter-of-simple-science/)** > > How climate scientists test, test again, and use their simulation tools. > [@](#): > > Coding the climate > > Some voices in the public debate over climate science have been critical of the fact that there is no standardized, independent testing protocol for climate models like those used for commercial and engineering applications. Climate scientists have responded that climate models are so different as to make such an “independent verification and validation” process incompatible. > > Steve Easterbrook, a professor of computer science at the University of Toronto, has been studying climate models for several years. “I’d done a lot of research in the past studying the development of commercial and open source software systems, including four years with NASA studying the verification and validation processes used on their spacecraft flight control software,” he told Ars. > > When Easterbrook started looking into the processes followed by climate modeling groups, he was surprised by what he found. “I expected to see a messy process, dominated by quick fixes and muddling through, as that’s the typical practice in much small-scale scientific software. What I found instead was a community that takes very seriously the importance of rigorous testing, and which is already using most of the tools a modern software development company would use (version control, automated testing, bug tracking systems, a planned release cycle, etc.).” > > “I was blown away by the testing process that every proposed change to the model has to go through,” Easterbrook wrote. “Basically, each change is set up like a scientific experiment, with a hypothesis describing the expected improvement in the simulation results. The old and new versions of the code are then treated as the two experimental conditions. They are run on the same simulations, and the results are compared in detail to see if the hypothesis was correct. Only after convincing each other that the change really does offer an improvement is it accepted into the model baseline.” ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [January 11, 2015, 12:34am UTC](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786/746 "2015-01-11T00:34:47Z")
> [@Sam\_Stone](#): > > I wasn’t responding to you, actually. I was responding to the comments that simply cast doubt on WWUT as a ‘denialist rag’ with the implication that anything quoted from there should be ignored. Do you ignore everything the Lancet puts out because they’ve been caught releasing some very obviously bad papers? Evan that does not help, the number of times the Lancet was wrong has been in a few occasions. And usually errors are taken care of by withdrawing the bad papers. WUWT does that only on very rare occasions, outrageous accusations of scientists falsifying the information, and of being fascists or Nazis are left there. And almost all commenters only cheer the denial even on articles that Watts has in a few occasions allowed to defend the scientists and the science. > [@Sam\_Stone](#): > > I wasn’t making a specific case against a specific article. I’m just pointing out that the proper way to think about the problem is to consider uncertainties on both sides, which implies a Bayesian approach rather than assuming that the models are the null hypothesis and therefore correct until opponents can ‘prove’ that AGW is not happening. > > One other nitpick - rather than arguing whether or not warming has ‘stopped’, the real argument should be based on how well the observations are tracking predictions. I wouldn’t expect the globe to cool regardless of whether man was influencing it or not, so the fact that it isn’t has nothing to do with the subject. So there’s foolishness on both sides. And the analysis I linked to shows that indeed the observations are tracking the predictions, so this idea that there is foolishness on both sides is very silly, one side almost monopolizes the misleading information. And is clear that they got you with the often already debunked model points that are repeated many times by the contrarians regarding computer models. [Previous page](https://boards.straightdope.com/t/is-global-warming-falsifiable/687786.md?page=37)