Is Anthropogenic Global Warming Falsifiable?

[jshore]

Quartz says:

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

If by “increased acidification”, you mean that the oceans are becoming more acidic, then you are wrong that this demonstrates increased absorption. (If, by increased absorption you mean that the oceans are absorbing a larger fraction of our emissions than they were before. If you are meaning that they are simply absorbing SOME of our emissions, then you are correct but you are not contradicting anything that GIGOBuster said.)

In other words, what GIGOBuster is saying is that many scientists believe that the oceans cannot continue to absorb the same fraction of our ever-increasing emissions as they are today. That does not mean that the oceans will not continue to absorb some emissions and continue to acidify…In fact, if our emissions continue to increase, it is even theoretically possible for the rate of such absorption (and hence acidification) to increase but still not fast enough that the oceans continue to absorb the same fraction of our emissions.

[What_Exit]

This might be a simplistic answer to the Op but:

AGW boils down to a few basics.
[ul]
[li]Concentrations of Greenhouse gases (mostly CO2) are increasing at a fast rate since the Industrial revolution.[/li][li]Greenhouse gases affect the climate.[/li][/ul]
Are these two falsifiable? I think they are.

Everything else is trying to build models to determine what effect the increase will have and that further increases will have.

What they are trying to determine with studies and their best highly educated guesses are; Will it adversely effect current human civilization and how much and how?

[MonkeyMensch]

Yes, I think it is. (This is in respect ot IPCC 4.)

Paleoclimatology shows long periods of both positive and negative correlation between atmospheric CO[sub]2[/sub] and global temperatures. Along with that is the commission’s glossing over of H[sub]2[/sub]O as the leading greenhouse gas in the models presented. I understand that the effects of water vapor are poorly understood, but to give confident answers while leaving out a major contribution to the effects is misleading, at best.

My other complaint is that IPCC 4 was reviewed by a number of the scientists whose work was being reviewed. It’s not horrible science since their work was already subject to peer review, but it would have been nice to have a board of scrutiny that had submitted none to such.

[Sage_Rat]

@MonkeyMensch

My other complaint is that IPCC 4 was reviewed by a number of the scientists whose work was being reviewed. It’s not horrible science since their work was already subject to peer review, but it would have been nice to have a board of scrutiny that had submitted none to such.

“IPCC reports are drafted and reviewed by thousands of scientists who are leading experts in their fields from around the world and contain extensive scientific and technical information and analysis. The drafts go through both expert and government reviews. U.S. government climate science experts led the U.S. review of the draft. The U.S. delegation to the Working Group II meeting included climate science experts from the National Aeronautics and Space Administration (NASA), the Department of Commerce’s National Oceanic and Atmospheric Administration (NOAA), the Environmental Protection Agency (EPA), and the Department of State.”

Quoth the US Office of Science & Technology Policy (PDF). Also note that this is coming from the Executive branch, under Bush (2007).

[GIGObuster]

@MonkeyMensch

I understand that the effects of water vapor are poorly understood, but to give confident answers while leaving out a major contribution to the effects is misleading, at best.

It seems that you did not read the thread.

[jshore]

@MonkeyMensch

Paleoclimatology shows long periods of both positive and negative correlation between atmospheric CO[sub]2[/sub] and global temperatures.

I don’t really think that is true. It shows strong positive correlation over the 750,000 years over which we have good data on both from ice core measurements. Going back further than that, the data are much less good but what we know of supports a general positive correlation.

Along with that is the commission’s glossing over of H[sub]2[/sub]O as the leading greenhouse gas in the models presented.

All the radiative transfer calculations include the effects of water vapor, and the water vapor feedback is an important part of the greenhouse effect. If you are trying to say that you are worried about humans directly changing the concentration of water vapor through our emissions of water vapor, that is simply not an issue. Water vapor concentrations are essentially slave to the temperature…so the way humans can influence them is indirectly, i.e., through the water vapor feedback whereby increases in CO2 concentrations cause warming which cause increases in water vapor, which cause further warming.

If you are referring to condensed water vapor, i.e., clouds in the atmosphere, they are certainly not glossed over either, although the cloud feedback is the biggest remaining source of uncertainty in regards to the climate’s sensitivity to increases in CO2.

Frankly, I think you are just repeating things that you have heard that are not correct. Let me ask you, how much of the IPCC report have you actually read?

[Quartz]

@jshore

If by “increased acidification”, you mean that the oceans are becoming more acidic, then you are wrong that this demonstrates increased absorption. (If, by increased absorption you mean that the oceans are absorbing a larger fraction of our emissions than they were before. If you are meaning that they are simply absorbing SOME of our emissions, then you are correct but you are not contradicting anything that GIGOBuster said.)

It was the last that I meant.

[Gorsnak]

Why is it that so many scientists think that Karl Popper is the last word on philosophy of science? I didn’t take many advanced classes in that particular field and remember little of what I learned, but the sorts of objections Blake is making to the falsifiability of AGW are all pretty much standard fare in the arguments against Popperian views in general. The Quinian observation that there is no data anywhere that falsifies any theory is decades old - “Two Dogmas of Empiricism” was published in 1951 for chrissakes - and writers on the philosophy of science have moved on.

If you want to criticize AGW for not being real science, you might want to update the philosophy a little bit.

[Deeg]

Wouldn’t the correlation between CO2 and temperatures be a way to falsify AGW?

[Quartz]

No. Correlation is not causation. The CO2 theory is pretty good, but that last step - that the CO2 released by humans is actually causing the warming we have seen - has yet to be shown. Plenty of people are beavering away to show it. Time will tell.

[Deeg]

Correlation is not causation but if studies showed no correlation between CO2 and temperatures that would be a significant blow to AGW.

[GIGObuster]

@Quartz

No. Correlation is not causation. The CO2 theory is pretty good, but that last step - that the CO2 released by humans is actually causing the warming we have seen - has yet to be shown. Plenty of people are beavering away to show it. Time will tell.

Oy. The last quote I gave regarding this also links to this RealClimate report:

RealClimate: How do we know that recent CO2 increases are due to human activities?

How do we know that recent CO2 increases are due to human activities?
Note:This is an update to an earlier post, which many found to be too technical. The original, and a series of comments on it, can be found here. See also a more recent post here for an even less technical discussion.

Over the last 150 years, carbon dioxide (CO2) concentrations have risen from 280 to nearly 380 parts per million (ppm). The fact that this is due virtually entirely to human activities is so well established that one rarely sees it questioned. Yet it is quite reasonable to ask how we know this.

One way that we know that human activities are responsible for the increased CO2 is simply by looking at historical records of human activities. Since the industrial revolution, we have been burning fossil fuels and clearing and burning forested land at an unprecedented rate, and these processes convert organic carbon into CO2. Careful accounting of the amount of fossil fuel that has been extracted and combusted, and how much land clearing has occurred, shows that we have produced far more CO2 than now remains in the atmosphere. The roughly 500 billion metric tons of carbon we have produced is enough to have raised the atmospheric concentration of CO2 to nearly 500 ppm. The concentrations have not reached that level because the ocean and the terrestrial biosphere have the capacity to absorb some of the CO2 we produce.* However, it is the fact that we produce CO2 faster than the ocean and biosphere can absorb it that explains the observed increase.

Another, quite independent way that we know that fossil fuel burning and land clearing specifically are responsible for the increase in CO2 in the last 150 years is through the measurement of carbon isotopes. Isotopes are simply different atoms with the same chemical behavior (isotope means “same type”) but with different masses. Carbon is composed of three different isotopes, 14C, 13C and 12C. 12C is the most common. 13C is about 1% of the total. 14C accounts for only about 1 in 1 trillion carbon atoms.

CO2 produced from burning fossil fuels or burning forests has quite a different isotopic composition from CO2 in the atmosphere. This is because plants have a preference for the lighter isotopes (12C vs. 13C); thus they have lower 13C/12C ratios. Since fossil fuels are ultimately derived from ancient plants, plants and fossil fuels all have roughly the same 13C/12C ratio – about 2% lower than that of the atmosphere. As CO2 from these materials is released into, and mixes with, the atmosphere, the average 13C/12C ratio of the atmosphere decreases.

Yes, there is already evidence that CO2 released by humans is actually causing the warming we have seen.

[Terry_Oldberg]

The position on falsifiability that is taken by the Intergovernmental Panel on Climate Change is pertinent to the discussion as governments tend to take the IPCC’s assessment reports as authoritative. Dr. Vincent Gray has been a reviewer of all of the past assessment reports that have been issued by the IPCC. At Tech know , Gray says, in effect, that he raised the issue of falsifiability of the IPCC’s climate models with the IPCC and that the IPCC blew him off on this issue. However, the IPCC did respond by revising the terminology of its assessment reports. Under the revised terminology, the IPCC refrains from stating that the models make “predictions.” Instead they make “projections.” This revision amounts to tacit admission by the IPCC that the IPCC’s models are non-falsifiable, for a model that makes predictions is falsifiable while a model that makes “projections” (as the IPCC defines this term) is non-falsifiable.

That the IPCC’s models are non-falsifiable places the IPCC’s models outside science, as virtually all present day scientists define “science.” However, that the models which provide the basis for the IPCC’s assessment reports are not scientific models is obscured by a misprepresentation by the IPCC. Under this misrepresentation, the IPCC represents that the models are the product of scientists. However while these people have scientific credentials, they are not acting as scientists. By calling them scientists, the IPCC muddies the waters sufficiently for scientifically naive politicians, journalists and others to take the IPCC’s assessment reports to be works of science.

To acquire the ability to see through the IPCC’s misrepresentation, one needs to understand the distinction between a prediction and a projection. A prediction is a proposition which states the probabilities of the various possible outcomes of a statistical event. In testing a predictive model, one draws a sampling of this model’s predictions and observes the actual outcomes. The model is falsified if the predicted probabilities of outcomes fail to match the observed relative frequencies of these outcomes.

As the IPCC defines a “projection,” it is a mathematical function that maps the time to the average global surface temperature. While a projection supports comparison of the projected to the observed average global surface temperature, it fails to support falsifiability in the associated model.

[GIGObuster]

Zombie thread!

It needs brains:

'Climate models are unproven'--Actually, GCM's have many confirmed successes...

Answer: Given the absence of a few duplicate planets and some large time machines, we can’t test a 100-year temperature projection. Does that mean the models can’t be validated without waiting 100 years? No.

The climate is an extremely complex system. Our observations of it are by no means complete – even with regard to what’s going on today.

This is a shortcoming we need to work hard to correct, but it is also an opportunity for validating model predictions: Find a measurement we’ve never taken, see how the models say it should turn out, and then go take it and compare.

Still, there are global temperature predictions that have been validated. We can start with one of the pioneers in climate science. Over 100 years ago, in 1896, Svante Arrhenius predicted that human emissions of CO2 would warm the climate. Obviously he used a much simpler model than current Ocean Atmosphere Coupled Global Climate models, which run on super computers.

Arrhenius overestimated the climate’s sensitivity to CO2 by a factor of 2. At the same time, he hugely underestimated the degree of warming, assuming CO2 would rise very slowly (who could have predicted the emissions the future held?). Still, it was a pretty impressive early success for models.

Running the clock forward: in 1988, James Hansen of NASA GISS fame predicted [PDF] that temperature would climb over the next 12 years, with a possible brief episode of cooling in the event of a large volcanic eruption. He made this prediction in a landmark paper and before a Senate hearing, which marked the official “coming out” to the general public of anthropogenic global warming. Twelve years later, he was proven remarkably correct, requiring adjustment only for the timing difference between the simulated future volcanic eruption and the actual eruption of Mount Pinatubo.

And let’s face it, every year of increasing global mean temperature is one more year of success for the climate models. The acceleration of the rise is also playing out as predicted, though to be fair, decades will need to pass before such confirmation is inarguable.

Putting global surface temperatures aside, there are some other significant model predictions made and confirmed:

* models predict that surface warming should be accompanied by cooling of the stratosphere, and this has indeed been observed;
* models have long predicted warming of the lower, mid, and upper troposphere, even while satellite readings seemed to disagree -- but it turns out the satellite analysis was full of errors and on correction, this warming has been observed;
* models predict warming of ocean surface waters, as is now observed;
* models predict an energy imbalance between incoming sunlight and outgoing infrared radiation, which has been detected;
* models predict sharp and short-lived cooling of a few tenths of a degree in the event of large volcanic eruptions, and Mount Pinatubo confirmed this;
* models predict an amplification of warming trends in the Arctic region, and this is indeed happening;
* and finally, to get back to where we started, models predict continuing and accelerating warming of the surface, and so far they are correct.

And I can see this error cropping up many times, the IPCC is not doing research, they review all the peer reviewed literature on the subject. The report is the best current understanding of the issue, if you have a beef with the modeling you need to follow the published research and point to the flaws.

[Honesty]

@Blake

What evidence can I collect that I can collect that will cause you to reject AGW?

This is easy. Show me data (computer models will do) that shows no correlation between high atmospheric carbon dioxide and variation of global temperatures.

[bri1600bv]

I think what the OP is saying is this, and I’m not a scientist BTW.

AGW people say “climate will do this”, ie more hurricanes (Al Gore), warmer temperatures. I read that one famous AGW said to the question of “how will things be different in 20 years due to AGW” said “see that highway out there (one by the east side of manhatten)…that will be underwater”. He said that in 1988 however and it’s not underwater 22 years later.

Anyway, scientiests make predictions. IF their predictions are right beyond a certain level of uncertainty (ie it couldn’t have happened by chance beyond a 5% level) then they are most likely RIGHT, upon further testing.

AGW people seem to take the opposite tack. They are right. That is a given. They make predictions. The predictions don’t come true. They say “well our models say there WAS a chance there would be cooling instead of warming, or whatever”. IE their hypothesis of AGW is now the NULL hypothesis. That’s usually the opposite of what is supposed to happen. They have to be proven wrong, not the other way around.

Then they say “let us incorporate these new data points into our models, making them EVEN BETTER!”. Fair enough, but that is called, in statistics, CURVE fitting. You can’t fit your model to data and then say your model is valid because it fits the data so well. Of course it does! How could it not?

They then make new predictions, which don’t come true and we repeat step 2 again (curve fitting).

So AGW can never be proven wrong…it is right and just needs to have its model tweaked a bit. That’s what the OP meant by unfalsifable, I believe.

As to the “this past decade is the hottest in recorded history”. How can they know that? First, didn’t they just come out and say their measurements are biased due to land use changes (more cities, locating temperature measurements near factory smokestacks, etc.)? Also, didn’t they just lose the temperature data for the years 1940-1970 or something? Haven’t they admitted to consolidating temperature measurements into LESS stations, biasing the measurements by throwing out higher altitude and more northerly stations?

At this point it’s looking more and more like a farce.

Al Gore said 4 years ago that we had 6 years to fix the planet, after that it was doom. Are we 2 years away from not having to worry about this anymore because it’ll be too late? Or will the goalposts be moved once again?

[GIGObuster]

@bri1600bv

I think what the OP is saying is this, and I’m not a scientist BTW.

That is ok, no one is perfect. This being a zombie thread you need to check on virtually all your rebutted points at the Skeptical Science web site:

Arguments from Global Warming Skeptics and what the science really says

[tomndebb]

Unlike other recent zombie threads that I have left open, this one had the usual abundance of personal hostility and there are several participants in the original who are no longer posting.

Terry Oldberg, you are welcome to repost your observations and questions in a new thread with a link to this one, but I am closing this thread.

[ /Moderating ]