Is Anthropogenic Global Warming Falsifiable?

Great Debates
101

Because people corrected for new data as it came in, they’re wrong?

There’s possibly thousands of different, shifting variables that effect the climate. How do you expect people to discover those before they shift in such a way as to change the climate in an unexpected way?

Climate modeling is an iterative process, and there’s no reason to expect otherwise. You make your best guess, try it against the real climate, see how it’s going wrong, form a hypothesis for why, add that back in, and see if it’s closer to real than it was before. Rinse and repeat.

No one has ever said that we won’t discover something which explains everything in a way that makes greenhouse emissions suddenly become a non-issue. But, the sheer existence of unforeseen possibilities isn’t a proof that an unforeseen possibility must be the real answer, and I can’t think why you would expect it to be.

It makes more sense to say that as various other factors are isolated, the closer things come to proving AGW if what remains matches greenhouse gas emissions volume more closely, which is I believe what’s happening.

Well first of all, you need to try. I’m not seeing why it’s our job to tell you how to make your case.

If you think you have a case, then make it and don’t just keep crying that we’re not making it for you.

Just to give you a bone, in the 50 year period from 1150-1200, the amount of volcanic gases and solar irradiance was fairly well an exact match to that of today from best we can tell.[sup]1[/sup] Judging by our various reconstructions via proxy data, the global temperature during that time period was probably about -0.3C compared to the 1961-1990 mean[sup]2[/sup] (which is 14.00C[sup]3[/sup]). We’ve been a match for the 1150-1200 volcanic/solar data since at least 1974. The average temperature from then (1974) to 2008 is +0.27C.[sup]4[/sup] Dividing that period into 5 year blocks, we have:

1974-1978 = -.03C
1979-1983 = +0.17C
1984-1988 = +0.17C
1989-1993 = +0.24C
1994-1998 = +0.37C
1999-2003 = +0.45C
2004-2008 = +0.53C

So, firstly, explain why our modern era is 0.57C higher than the 1150-1200 period. Secondly, explain what has been causing the rise in temperature over the last 35 years if it isn’t the sun and volcanoes.

[sup]1[/sup] http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_Ch06.pdf p. 477 (Note that the baseline is the 1500-1899 mean)
[sup]2[/sup] IPCC Ch. 6, p. 467 (Baseline is 1961-1990 mean)
[sup]3[/sup] Search - The Encyclopedia of Earth
[sup]4[/sup] http://data.giss.nasa.gov/gistemp/tabledata/GLB.Ts+dSST.txt (Baseline is 1951-1980, 14C)

102

Except that it does. Most models incorporate tree ring data. Either it turns out that they don’t match temperature and improve model fit anyway, or they do match the temperature and the models are wrong. Neither option makes the modelling exercises look good.

Nonsense. This is exactly like the creationists saying that evolution violates the laws of thermodynamics.
CO2 absorbs heat in a bottle, cows eat grass in a cage, people eat food in a hospital. That doesn’t allow you to extrapolate the effect of those processes on a chaotic system on a global scale.

No physical laws need to be violated for increases on CO2 to have absolutely no measurable effect on global temperature. All we need is some alternative mechanism to increase heat transference to space (eg increased storms), decrease radiation (eg global dimming) or, increase albedo (eg cloud over).

Saying that any climate observation violates the laws of physics shows a gross ignorance of how uncertain our understanding of climate is. At best we have theories, not laws.

103

Then tell us what they are.

No, because the theory allows them to incorporate any data as it comes in it’s not science. The problem isn’t with incorporating new data. The problem is that there is no data that can’t be incorporated.

I don’t.

Popper, however, demands that the proponents of a supposedly scientific theory to state clearly what shifts are incompatible with the theory.

Can you do that?

Yep, just like Intelligent Design, or Freudian Psychology or Astrology.

I have no problem with iterative sciences per se. The problem comes when the proponents can not make predictions that would be incompatible with their hypothesis.

Nor do I.

Huh??? You seem to have lost the end of your sentence. If without then.
“if what remains matches greenhouse gas emissions volume more closely then……???

Then you need to read the article by Popper, because that is precisely your job. If you can’t tell me how to falsify your theory then your theory isn’t scientific.

Again, all you are doing here is hollering loudly that you can never make AGW meet the Popperian definition of science. I’m not crying that you aren’t making my case. I’m crying that you aren’t meeting the most basic Popperian standard of science.

But thank you for making it so clear to everyone that you agree that AGW can not meet that standard of science.

An unknown process.

I’ll say it again: You don’t need to accept my theory that the dark matter/energy discrepancy is caused by pixies just because you haven’t discovered an alternative explantion yet. A scientist isn’t required to accept an unscientific hypothesis just because she has no better alternative. That’s not how science works. An admission of ignorance is always acceptable in science, no alternative need be postulated.

104

The models are only quibling a few degrees C. None of them are predicting cooling. The models can all be wrong and it wouldn’t change AGW.

Evolution doesn’t violate the laws of thermodynamics in any way. It’s not even related.

Yes, they do. CO2 doesn’t change it’s properties once it’s out in the atmosphere. The earth radiates energy, CO2 absorbs it. It isn’t a cow.

None of this changes the fact that CO2 absorbs IR. It may change how much, but it wont change that it does. Increased CO2 leeds to increased temperature. Wave your hands with maybe’s all you like, CO2 absorbs thermal radiation. The earth emits thermal radiation.

Well then it’s a good thing nobody said that. The law is that CO2 increases the earths temperature, not how much.

105

What remains ties in to AGW IF the levels match emission levels. There is no “then”.

I have told you how to disprove it, way back on page 1 and again in my last post. All you have to do is find something which explains the current and historic climate better than the currently accepted science. If you can make a climate model that comes closer to reality than what we have and it doesn’t rely on greenhouse gas emissions to accomplish it, then you’re reducing the possible effects of greenhouse gases to whatever difference still remains between your model and real. If you can show that greenhouse gases aren’t collecting in the atmosphere like believed, then there’s a decent chance that you’ve disproved global warming. If you can show that Earth’s atmosphere has no effect on planetary temperature, then you’ve entirely disproved AGW.

There’s any number of ways to disprove AGW wholly or nip off the amount of climate that can be attributed to gases, but stated most simply, “All you have to do is find something which explains the current and historic climate better than the currently accepted science.” Isolate everything there is in the climate and explain it all, and if there’s no AGW, then there you go.

But so far, isolating things has only established how much of our current climate is due to greenhouse gases, rather than showing how little of it is.

106

Umm… that’s not showing that the human emitted CO2 is significantly absorbing CO2.

Except we are separately seeing increased acidification of the oceans demonstrating increased absorbtion.

I’ve expressed my lack of faith in models elsewhere. And I’d rather not wait 50+ years for results. More research is required!

107

Wait a tick.

How is your “unknown process” falsifiable? Or the admission of ignorance?

108

So you can show that that CO2 has different physical properties?

As mentioned before, models predicted the values and importance of the water vapor feedback. Confirmation came recently but many skeptics just close their eyes.

109

A good model should predict the future, starting from a historic date. Right now is 50 years in the future from sometime, and we know the starting conditions just fine from our recordings. Why wait 50 years when we can just predict now and see how close we get?

Amazingly, that’s what we do.

110

And I explained in depth how this is not a method of disproving it at all. repeating the same proven nonsense doens’t make it true.

It isn’t, what’s your point?

I don’t think you actually read Popper’s article, did you?

111

No, but just because it can do it doesn’t mean that it is doing it. And if it is, is it doing it to a significant degree?

Cite? I was under the impression that this was built in to the models, so you cannot say that they predicted it.

I was clued in about water vapour feedback some years ago.

112

No, it isn’t.

Models are calibrated to past temperatures. Using them to predict the same period of the past is perfectly circular. Of course they match. All the forcings and fine tunings were designed to make them match.

Now if someone were to calibrate a model for 1900-2000 and then test it against 1800-1900 and get >95% confidence you might have something. Or if someone constructed a model using only atmospheric composition data and physical constants without any reference to the temperature data.

But at the moment all we’ve got is circular reasoning where we “test” models constructed as best fit to past temperature records by comparing how well they fit past temperature records.

113

http://www.sciencemag.org/cgi/content/short/310/5749/795

114

Testing them against recent volcano eruptions was still possible

115

Where? Your response to my first post displays full acceptance of my falsifying criteria. You say, “I’m gonna do it!” And proceed to make a stab. The only problem is that your stab was a fantasy rather than data.

If all the question there is to this thread is whether global warming is falsifiable, then the answer is yes. Both you and I agree that there is a way for you to disprove anthropogenic global warming. End of debate.

BUT, if you want to move to the next step and actually falsify something, merely supposing the existence of a natural, unknown source is meaningless.

I can throw a ball through a vacuum, see that it’s following a parabola and suppose that invisible aliens are moving it like that on a whim, rather than the theory of gravity is correct. But the ability to make such a supposition doesn’t disprove anything.

I can propose ways to falsify gravity, but until I’ve got evidence to show it, I’m not doing anything but masturbating.

But in summation, again: Yes, you can falsify AGW. Show that our understanding of the physical properties of greenhouse gases in the atmosphere is incorrect, and/or provide a working, predictive model of the Earth that explains what is going on better.

116

Blake - I seem to be having some difficulty understanding where you’re coming from. You agree:

  1. That GHGs retain extra heat.
  2. That humans put extra GHGs in the atmosphere.
  3. That we observe an increase in the Earth’s temperature that is of the right size counting both human GHGs and natural factors.

If you agree with all three, it seems to me that you agree with AGW. If not, which of the three do you disagree with?

That’s not an alternative hypothesis. That’s a necessary component of AGW. Is GHGs don’t retain heat, AGW is dead.

It doesn’t matter when the IR absorbance of GHGs is discovered. Principles of physics are not numbers.

  1. If you have a data set: 1, 2, 3, 4, 5… you can’t test the hypothesis that the next datum will be 6 using that data set. You need new data to falsify the hypothesis.

  2. If you have: Boyle’s Law, Charles’ Law, and Avogadro’s Law, you can’t throw out Boyle’s Law and collect a new one because you want to test the Ideal Gas Law.

You seem to be asking for us to do #1, when the situation is #2. Unless I’ve got you wrong - perhaps you could explain further?

  1. Any evidence demonstrating that CO[sub]2[/sub] and other GHGs do not absorb heat.
  2. Any evidence that the CO[sub]2[/sub] in the atmosphere does not come from fossil fuels.
  3. Evidence that the sun’s intensity (e.g. TSI) has been increasing sufficiently to account for observed warming.
  4. Evidence of sufficient volcanic action to account for observed warming.
  5. Evidence that the amount of GHGs in the atmosphere does not account for observed warming.
  6. Evidence of unexplained heat being brought into Earth from space of about the right amount to account for observed warming.
  7. Evidence of unexplained heat being brought to the surface of Earth from within of about the right amount to account for observed warming.

I would guess that your best bets are #3-7.

117

Why do you have a lack of faith with models? Is it all models you have a lack of faith with, or just climate models? Do you believe British nuclear weapons are duds, or will explode when they need to?

What do you base this trust on? The computer models used to guarantee their detonation?

118

I have a problem with your #1 and #2. Let’s say I have a theory that says that warts are caused by heat fairies who respond to the heat of the sun. Can I claim that that theory is falsifiable by showing that my theory is falsified if anybody can demonstrate that the sun is not a source of heat? Or that the majority of the heat we feel on earth doesn’t come from the sun?

I know little about the rest, but I don’t think the first two items on your list contribute to showing that AGW is falsifiable.

119

I agree that #1 and 2 on my list are extremely unlikely for any new evidence to come to light. Blake would probably agree that they’re solid, but I can’t speak for him/her. Quartz, on the other hand, suggests in post #66 that #1 would be a place to check for falsification.
The other thing is falsifiability is a philosophical concept. It doesn’t matter that we’re extremely confident that CO[sub]2[/sub] absorbs at 13-15 μm, falsifiability (see the references to Karl Popper earlier in the thread) is about whether that value can be measured or not, not about whether we think the measurements that have already been made are accurate or not.

120

Are you claiming that global climate models incorporate tree ring data? How do they do that? I get the feeling that your idea of modeling is the sort of empirical fitting to parameters that you find it some fields. That is not how climate models work. They are based on physical principles and, while it is necessary to parametrize certain features (such as those of clouds) that occur at sub-grid length scales, the parameters that can be “tuned” are not very many and are usually constrained by either the physical process itself or some very basic issue such as the model maintaining a roughly constant global temperature in “control scenarios” (i.e., the absence of any net forcing).

First of all, I don’t think any of the temperature data sets…and almost certainly not either of the surface ones…shows a net cooling trend over the last 12 years. Even if one does, it would not if you went to 13 years or 11 years. (One can cherrypick a little bit by starting with the 1998 El Nino, which had a global temperature that was more than 2 standard deviations above the trendline.)

Second of all, periods of cooling are simply not unexpected over such short periods (of years to about a decade or so) for a system that consists of a linear trend of ~0.015-0.02 C/yr but with year-to-year variability on top of that which is almost an order of magnitude higher…and any careful analysis of the trend lines that also includes the error bars on the trends (and these need to be calculated carefully because of correlations) shows these negative trends to lack statistical significance. The people who try to claim falsification of AGW based on negative trendlines over periods of less than about 15 years are not demonstrating Popperian falsification but rather just statistical ignorance. (See here for a discussion of this by “Tamino”, a blogger with wizardlike data and statistical analysis skills.)

Third of all, there are thousands of papers published each year in climate science and the fact that there was one that predicted that we would have that ~20 more years of cooling within the context of a model that in general predicted warming due to AGW does not mean it represents the general consensus in the field. In fact, that paper by Keenlyside et al. was met with considerable skepticism and plenty of people (myself included) who would be willing to wager that it’s prediction will be wrong.

As for the general issue of falsification, I don’t want to repeat what I said in the other current AGW thread, so I will just link to it.