The Trenberth article contains so many glaring errors and biased assumptions, it’s hard to know where to start.
First of all, the difference between theory and hypothesis:
The problem is not with dueling hypotheses, it is with dueling theories regarding the processes resulting in observed global warming. One theory states: Observed global warming is the result of human greenhouse gas emissions. Another theory states: Observed global warming is not caused by human greenhouse gas emissions, but is a result of natural geophysical processes.
The statement, “Global warming is the result of human greenhouse gas emissions” is not an hypothesis, it is a proposition, or at best, a simple theory. A theory is an explanation of process based on a body of observation.
Hypotheses, on the other hand, are predictive “if…then” statements used to test a small subset of a theory as an adequate explanation of observations, thus either strengthening or weakening the theory. The results of an individual hypothesis never disprove a theory. A theory can only be weakened and eventually replaced by the accumulation of a body of evidence that contradicts the theories explanation of observations, and the formulation of a new theory that provides a more adequate explanation.
We can test the theory of anthropogenic global warming with the hypothesis: If observed global warming is caused by human greenhouse gas emissions, then we should find a positive correlation between the amount and rate of greenhouse gas production and global average temperature rise. This is weak test of the theory, since, if we find such a positive correlation, we merely confirm the existing theory. No new information is gained. If we fail to find the positive causal correlation, it may be because we just have not looked hard enough yet, or haven’t looked in the right places. The truth is still out there!
The null hypothesis would be stated as: If observed global warming is caused by human greenhouse gas emissions, then we should not find a negative correlation between the amount and rate of greenhouse gas production and global average temperature rise. This is a much stronger test of the hypothesis, since it only takes one instance of negative correlation to negate the hypothesis and weaken the theory as an explanation of observations.
This is the process of Science, the Hypothetico-deductive Method of Theory Confirmation.
Secondly, Trenberth repeatedly fails to make a distinction between Global Warming and Anthropogenic Global Warming. There is no question that the average global surface temperature of the Earth has been increasing steadily over the past 20,000 years or so, else, we would still be skirting glaciers on our daily commute. The question is: What is the contribution of anthropogenic greenhouse gases to this warming, and, what effect will reduction of anthropogenic greenhouse gases have on this on-going global warming, if any?
Since we do not yet fully understand the natural geophysical processes that result in observed climate variations over geologic time periods, it is very difficult, if not impossible, for us to fully understand the contribution to global climate variation resulting from anthropogenic greenhouse gases. Wild predictions of future catastrophic weather events are simply science fiction prognostications with as much scientific validity as a Star Wars movie.
The periodic reports by the IPCC are not scientific documents, they are produced to give policy-makers estimations of the relevant probabilities of various climate scenarios, as an aid in preparation of national and international policies dealing with climate variation. These statements of probability have been inflated by the world press and by politicians anxious to make a name (and fortune) for themselves. Probability has been turned on its head into certainty and is being used by all manner of organizations and individuals to forward their individual agendae. Hyperinflated scare stories of sea level rise, catastrophic flooding, heat waves and droughts have been used to justify continued human growth and development in the face of dwindling natural resources and increasing air, water and soil pollution, all in the name of environmental justice.
At some point, increasing evidence of negative correlations between global average atmospheric CO2 concentrations and global average surface temperature will falsify the null hypothesis and greatly reduce the adequacy of the anthropogenic global warming theory as an explanation of observed global average surface temperature increase. Environmental organizations, politicians and science policy organizations will find they’ve hitched their wagons to a black hole. Their unceasing drum-beat for Anthropogenic Global Warming will ultimately discredit their otherwise worthwhile and necessary programs to reduce human pollution as a result of unrestricted human population and economic growth.
Mike Haseler says:
January 16, 2011 at 4:27 pm
“Finally, I’m beginning to understand how someone like Trenberth could possibly call himself a scientist and come out with the nonsense he does. It seems that there has been a movement called “post-modernism” which objects to the concept that science derives truth by using the scientific method or to quote:”
Extremely well-written. I have lived and worked with these people for more than forty years. Some of them do not understand science or scientific method but many of them had the same training that I did. In the case of the latter, to a man they have made a Marxist turn and insist on describing and analyzing science from the point of view of a human value system. By far the most popular value system among these people is Marxism. And many people have succumbed to Marxism without knowing it. Thomas Kuhn’s Structure of Scientific Revolutions is thoroughly Marxist because of its fundamental postulate that our systems of belief, especially science, act as causes which override our attempts to act as neutral observers as we perceive the world, converse with others, or judge our hypotheses. In other words, it invites the propagandist to take over science education. Post-modernists believe that the fundamental role for the scientist is activist. If permitted, they will take over science, through its funding agencies, and they will dictate what is accepted science.
AGW hypothesis already broken.
See http://www.climate4you.com/ClimateReflections.htm#20080927:%20Reflections%20on%20the%20correlation%20between%20global%20temperature%20and%20atmospheric%20CO2
Smokey: only one of those is actually a “prediction” of AGW theory (whatever that is.) The stratospheric temperature one would fall under that banner, if anybody could actually find out where that prediction was made. Willis had a post back in April where he requested a citation that did not seem to elicit a response. Apparently it is a prediction, but nobody actually predicted it.
As for the rest, they are better described as inputs to the theory, i.e., the world is warming, CO2 is rising in the atmosphere and the oceans, ice is melting, etc., are all data points, not predictions. A prediction is “if this then that” and predictions should preferably be somewhat (if not completely) unique to a given theory from which they were made. It does not do any good to say that ice will melt as a result of AGW when simply being warmer will do that – you want your predictions to be isolated enough that the only reason it has happened is because of your theory.
Gates does not understand that. I wonder, too, how many climate scientists understand this (or do they assume they can be so weak on this point because the general populace, those like Gates, do not?)
Mark
“When danger reared it’s ugly head, he bravely turned his tail and fled” -Eric Idle
I’m with you up to “… otherwise worthwhile and necessary programs to reduce human pollution as a result of unrestricted human population and economic growth.”
Has it occurred to you that perhaps this narrative is itself a product of gross exaggeration and misstatement for ideological reasons, as are the catastrophe predictions of AGW alarmists?
Mark T says:
January 16, 2011 at 5:53 pm
Smokey: only one of those is actually a “prediction” of AGW theory (whatever that is.) The stratospheric temperature one would fall under that banner, if anybody could actually find out where that prediction was made. Willis had a post back in April where he requested a citation that did not seem to elicit a response. Apparently it is a prediction, but nobody actually predicted it.
________
Here’s an excellent article from 1974 that cover many of the “predictions” made by a GCM of the era when factoring in the effects of increased CO2. including the cooling of the stratosphere:
http://tiny.cc/kp29t
All along of course, GCM’s have made it clear of the uncertainties, but the general direction of stratospheric temps was quite clear (i.e. down), and as we all know, that is exactly what has been occurring:
http://www.ncdc.noaa.gov/bams-state-of-the-climate/2009-time-series/stratosphere
The simple physics behind this is not a mystery…increase the concentration of GHG’s, the transmission of LW radiation to the stratosphere slows and thus the stratosphere cools.
Peter O’Brien, sorry to have to agree but it’s true, you are not the sharpest tool in the box, realists have seen this sort of ‘I am a denier stuff before’ to cover for someone who is really an alarmist. You know and I know that the all AGW scam is based on exactly what you claim to have been thinking about, what humans do to contribute to warming the planet!! So let me get this straight, what are you proposing? That we all freeze, well here in UK a lot of us are as we cannot afford our heating bills due to levy’s foisted upon us in the name of AGW, we cannot afford to drive as petrol is now almost £7 a gallon (in fact our police patrol’s cannot afford to use their patrol cars), we can barely afford food, a loaf of bread not costs £1.30. Of course this does not affect the elite’s, just the middle classes who are working for a living. You may get your wish, but be careful what you wish for!!
Nice try. What you’re saying is somewhat useful with AGW; but they don’t use that term anymore. Try coming up with a rebuttal to Climate Change or Climate Disruption. Those terms don’t need to be in exact lock step with CO2. They keep changing the rules so we can’t hit a moving target, now everything is caused by increasing CO2. Until CO2 stops rising for a few years and climate change keeps on coming we’re doomed!
Theo Goodwin says: “If permitted, they will take over science, through its funding agencies, and they will dictate what is accepted science.”
Well said!
Peter O’Brien,
It just seems to me that the heat we generate is a NET addition to atmospheric temperature and would be a more likely anthropogenic contribution to any putative ‘global warming’ than CO2 emissions.
yes and no, the additional heat leaves the earth on the same day it is generated. And it is minor. Oh, sorry, you may have calculated the difference, what was your number?
anne says:
January 16, 2011 at 11:04 pm
Anne,
you miss my point entirely. I am not proposing the we humans discard our standard of living in order to alleviate some putative global warming. Certainly we can do some things better in order to use a finite resource more wisely. That’s just technological advance. But it doesn’t include taxing carbon (as our government here in Australia is proposing), closing down coal fired power stations or wasting billions on futile solar and wind power generation.
My point is – it seems to me anyway – that the heat we generate, which is a natural and inevitable (and indeed desirable) result of human development, is a more likely contributor to global warming (whatever it may be) than CO2 emissions. I believe that whatever warming has already occurred is part of the natural cycle and, in the main, beneficial.
I am certainly not an ‘alarmist in denier’s clothing’!
All of the stuff we burnt including nuclear and renewables gave out heat at the rate of 1/2000 th of the solar energy falling on Earth.
Graeme W
Decreasing stratospheric temperatures are a sign of warming due to an enhanced greenhouse effect. If the warming were due to a change in solar irradiance one would expect the stratosphere to warm.
jrwakefield
Most simply means more than 50 percent and by very likely the IPCC means with more than 90 percent certainty.
Mark T
See Global Change in the Upper Atmosphere by Laštovička et al 2006:
The reason, as I understand it, is that an enhanced greenhouse effect results in more radiation being trapped in the lower atmosphere. This radiation would otherwise pass through the stratosphere, thus warming the stratosphere, so any reduction in this radiation can be expected to result in stratospheric cooling.
On the other hand, if global warming were caused by an increase in solar irradiance, there would be more radiation passing through the stratosphere (as there would be more radiation coming from the sun) and so one would expect the stratosphere to warm.
The fact that stratospheric cooling is what has been observed is strong evidence that the current warming is the result of an enhanced greenhouse effect.
Mark T
Such a projection will of course have a number of caveats as the temperature rise will depend not only on the rate of human emissions over that period but also on various natural forcings such as variations in solar irradiance and major volcanic eruptions. However, James Hansen famously made a projection in 1988. This was in fact three projections, based on three different emissions scenarios. For the scenario that best matches our actual emissions the projected temperature rise comes within 5 percent of the observed temperature rise. See this page on Real Climate for a more detailed analysis.
Roger Otip says:
“>Most simply means more than 50 percent and by very likely the IPCC means with more than 90 percent certainty.”
And tell me pray where that “90%” figure comes from. I seem to recall the only place I could trace that figure to was some kind of opinion poll amongst climate “scientists”.
The simple truth is that if you look at the data scientifically, the reported rise is well within the normal global temperature noise signal and so there is clearly and unambiguously less than 50% confidence that external forcing has caused a majority of the change.
90% from an opinion poll, when real statistics will give much less than 50% — the IPCC are living in a land of post-modernist make believe not science!
“The fact that stratospheric cooling is what has been observed is strong evidence that the current warming is the result of an enhanced greenhouse effect.” Again, a giant leap of faith that there is no other possible cause.
The IPCC report footnotes set out various definitions they use within the report. Their degrees of certainty are given as follows:
The warming signal in the temperature rise over the last three decades is above the 95% statistical significance level meaning there is less than 5% chance that it is simply the result of natural variation.
Roger Otip says:
January 17, 2011 at 7:02 am
if you look at the data scientifically, the reported rise is well within the normal global temperature noise signal
The warming signal in the temperature rise over the last three decades is above the 95% statistical significance level meaning there is less than 5% chance that it is simply the result of natural variation.
______
Roger, you are correct but I suspect there are very few on this blog who will listen. Even if all the sea ice on both poles melted and Greenland and Antarctica melted, and the sea levels rose by 50 feet, you’d get some who’d say it was just a recovery from the last interglacial or some such nonsense.
R Gates:
Your posts on WUWT keep demonstrating that you really, really do not understand how science works. For example, the post of yours at January 17, 2011 at 8:36 am says;
“Even if all the sea ice on both poles melted and Greenland and Antarctica melted, and the sea levels rose by 50 feet, you’d get some who’d say it was just a recovery from the last interglacial or some such nonsense.”
Firstly, none of those things can happen within millenia because the laws of physics do not allow it.
Secondly, if they were to happen then none of those happenings would – of itself – be evidence of its cause.
The Earth is warming and there is substantial evidence that it has been warming for about 300 years. It is a fact that the cold era from which that warming is happening is called the Little Ice Age (LIA).
Nobody knows why the LIA happened and nobody knows why the Earth has been warming from it for about 300 years. But until about 1940 (i.e. until 70 years ago) the anthropogenic emissions were too small for them to have had any effect on the warming for that effect to be discernible.
So, the problem for people who want to assert that the anthropogenic emissions are contributing to the warming is that they need to show the warming after 1940 differs from the warming before 1940. And they cannot. Indeed, the warming in the twentieth century occured in two periods: i.e. 1910 to 1940 and 1970 to 2000. Those periods have the same rate of warming as far as anubody can tell, and there has been no discernible warming of the globe since the twentieth century.
I hope that helps. You still have much to learn before you have grasped the basics of these matters, but the info. I have given you here is a start.
Richard
Richard S Courtney says:
January 17, 2011 at 1:00 pm
R Gates:
Your posts on WUWT keep demonstrating that you really, really do not understand how science works.
_____
What I understand is that if I believe that it is more likely than not that AGW is happening, then I obviously don’t understand the science. How could it be otherwise in your world-view? These assertions that I “really really do not understand how science works” amount to nothing less than an ad hominem attack on me. I understand the science well enough to have formed an honest and educated opinion on the subject. I have stated quite clearly a list real world measurable effects that are likely attributable to AGW. Until someone offers a competing theory to AGW, that completely explains the simultaneous occurrence of all these effects, then, for the time being, AGW is the best we’ve got. And when I hear people saying, “but that effect is from warming, not from the CO2,” then of course I realize that there is indeed a big gulf between the “warmists” and the skeptics…
R Gates:
At January 17, 2011 at 1:00 pm you assert:
“I have stated quite clearly a list real world measurable effects that are likely attributable to AGW. Until someone offers a competing theory to AGW, that completely explains the simultaneous occurrence of all these effects, then, for the time being, AGW is the best we’ve got.”
No! That is twaddle!
Each of your “realworld measurable effects” is covered by the null hypothesis. Therefore, according to the scientific method, the null hypothesis is the “best we’ve got”. Until you can disprove the null hypothesis there is no reason to even consider the AGW conjecture.
I keep explaining this to you (as I did in the post you have answered in your post that I quote). And pointing out your deliberate ignorance of it despite repeated and various explanations is NOT an “adhominem attack”: it is simply a fact.
Richard
R. Gates
It seems these self-proclaimed skeptics are not very skeptical when it comes to their own pet hypotheses.
REPLY: Ditto http://www.legjoints.com/ClimateChangeDenial/
Direct observations find that CO2 is rising sharply due to human activity. Satellite and surface measurements find less energy is escaping to space at CO2 absorption wavelengths. Ocean and surface temperature measurements find the planet continues to accumulate heat. This gives a line of empirical evidence that human CO2 emissions are causing global warming.
Skeptical Science