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Is the Anthropogenic Global Warming hypothesis falsifiable?

Scientific theories must make predictions that not only bolster the theory if the predictions come true, but also falsify the theory if the predictions turn out to be wrong. Some climate skeptics believe that the AGW hypothesis is impervious to falsification, short of waiting several decades to directly it, and pending that test, climate scientists and in particular climate modelers have boundless latitude to massage their theories and models to match what has become their pet hypothesis.

Implications to Other Questions

Will IPCC climate models make accurate predictions?
Is the Anthropogenic Global Warming hypothesis falsifiable?

Experts and Influencers

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Agree
Experts In Climatology


RealClimate    Climatology Blog
Agree
There are indeed a great many aspects of the Theory of Global Warming that are falsifiable without waiting for the next century’s climate to come upon us. There are ... laboratory tests of basic physics... [and] ...field tests of the predictions of these basic physical theories... [We can also] compare the predictions of the theory against observations of recent climates, and of climates of the more distant past [using climate models that] encapsulate the assumptions of the theory...
16 Feb 2006    Source


Andrew Dessler    Climatology Professor
Agree
...because the models are constructed with knowledge of the present climate, this is clearly a weaker test than one in which you do not know what the answer is in advance. ... So how do we get a sense of the reliability of climate models? The approach taken by the scientific community is really the only one available: analyze and validate the individual processes in the climate models.
25 Feb 2009    Source


Disagree
Experts In Science


S. Fred Singer    Head of NIPCC, Astrophysics Professor
Disagree
The climate business doesn't work the way laboratory science does. If the next ten years turn out to be cold, this by itself does not prove anything. ... They'll say, "Well, that's not really long enough. We need 100 years of satellite data that show cooling." And inevitably during the next 100 years, you're going to have some warming, because the climate is constantly changing.
01 Jan 2000    Source


Experts In Geography


Timothy Ball    Environmental Consultant, Geography Professor
Disagree
If we apply Popper’s falsifiability to [AGW's] assumptions then AGW fails... Observations in all records of any duration for any time period show that temperature increases before CO2 increases... Despite this evidence all models continue to use the assumption. It is not surprising therefore that the hypothesis in the form of the models also fails the fundamental definition of science because their predictions are consistently wrong. It is also not surprising considering the lack of validation.
10 Oct 2008    Source



Comments

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0 Points      Benja      15 Jul 2010      General Comment
Valuable insight from Ray Ladbury found on Real Climate here:

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There seems to be a lot of misunderstanding about falsification/verification of theories and rejection/replacement of models. If you have a theory that gives a definitive prediction of an event, and that event does not occur, then that model is falsified. However, most models give statistical predictions, and statistical tools for model verification are mostly comparative–it’s a question of which model is more likely to have produced the result. In classical frequentist statistics this manifests in terms of comparison between a hypothesis and a null hypothesis. The likelihood ratio is another tool, as are comparisons between the Bayesian prior and posterior distribution.

In the case of climate models, you really don’t have a credible rival to models that feature a significant CO2 sensitivity. This sensitivity is constrained by multiple, independent lines of evidence, so if the sensitivity in the models were to be wrong, ALL of these other data would cease to make sense and have to be reinterpreted. Much more likely would be a hard look at other forcers–especially aerosols, clouds, etc. So if the predictions of models started to be drastically different from reality over an extended period of time, the models would likely be modified slightly, with little change in CO2 forcing. In this sense the situation is very close to that of evolution.

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0 Points      Terry Oldberg      05 Apr 2011      General Comment
Benja's argument is based upon a false premise. The premise is that the climate models make predictions. Actually, they make projections. A model that makes predictions is falsifiable. A model that makes projections is not. As the climate models are not falsifiable, they are not scientific.


0 Points      Benja      05 Apr 2011      General Comment
Gotcha climate scientist again!

Climate scientists make the elementary semantic error of confusing predictions with projections!

I'd reply with a counter-gotcha but I suspect you have a bottomless bag of gotchas.