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.
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Richard S Courtney says:
January 17, 2011 at 2:26 pm
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
_____
Richard, first, the years of AGW being a “conjecture” have long ago passed us by. Sometime in the 1990’s it certainly became a full and honest “Theory”. This causes AGW skeptics no small amount of heart ache as they now need to have an alternative theory that explains the major trends in the climate that AGW Theory does.
What is difficult for honest AGW skeptics to understand is that AGW Theory is dealing with a system (i.e. the climate) that exists on the edge of chaos and that can never be described in detail and has far too many inputs and variable for a complete and exact description. A very good analogy is this. If you see a rain cloud forming on the horizon, and know the rain usually comes from that direction, and then see lighting and hear thunder, you might make a good case that it is going to rain. You might even see the rain falling a mile a way and headed your direction. Now, tell me exactly where the first raindrop will fall on your car window. No amount of computing power could ever predict that, just as no amount of computing power could ever predict exactly when the Arctic will be ice free in summer, but the trend has been predicted and within a range, we can be pretty certain it will happen. And that trend has been predicted by all the GCM’s when considering the 40% growth in CO2 since the 1700’s and its continued growth. We know the Arctic will be ice free BECAUSE OF INCREASING GREEN HOUSE GASES, just as we know from the analogy above, that the first rain drop will fall on the window…we just don’t know exactly when, and never can when dealing with a complex and chaotic system.
Roger Otip says:
January 17, 2011 at 4:40 pm
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.
_____
Again Roger, I think you’re assuming far more interest to your honest attempts than may be warranted…but carry on!
Roger Otip says:
“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.”
No mate. It means that there is less than 5% chance that there has been no warming, that’s all. It say’s nothing about the cause itself. There are cyclical natural variations with periods much longer than three decades – orders of magnitude more. Like, for instance, cycles of solar activity.
The below is a good key to why there is so much confusion when interpreting statistics:
“John Johnston says:
January 18, 2011 at 12:25 am
Roger Otip says:
“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.”
No mate. It means that there is less than 5% chance that there has been no warming, that’s all. It say’s nothing about the cause itself. There are cyclical natural variations with periods much longer than three decades – orders of magnitude more. Like, for instance, cycles of solar activity.”
As John Johnston points out, what some like to see as an evidence of human activity, is only a statement of difference. To that can be added that the warming when compared to beginning of 1900 is almost the same as saying the warming compared to end of 1800. Going by what was tought in school, this is almost same as saying that it is warmer now than it was at the end of little ice age.
Well, if we compare to the end of little ice age, and do not consider us in a new ice age, it would be expected that it is wamer outside of an ice age than inside an ice age. That fact alone has very little to do with a conclusion on human activity effects.
— Mats —
R. Gates:
Your post at January 17, 2011 at 7:33 pm yet again demonstrates your deliberate ignorance in that you refuse to face reality and cling to your unsubstantiated beliefs instead.
I ask everybody to read it before reading anything else you write.
Your illogical rants are annoying to those of us who prefer science to superstition.
|Richard
Is it ok if this article is translated to dutch and possible put online at climategate.nl?
[Reply: This question should be put in Tips & Notes, where Anthony will be sure to see it. ~dbs, mod.]
Richard S Courtney says:
January 18, 2011 at 1:12 am
R. Gates:
Your post at January 17, 2011 at 7:33 pm yet again demonstrates your deliberate ignorance in that you refuse to face reality and cling to your unsubstantiated beliefs instead.
I ask everybody to read it before reading anything else you write.
Your illogical rants are annoying to those of us who prefer science to superstition.
|Richard
______
You are welcome to your opinion, and likewise, I to mine. My confidence that AGW is likely occurring is firmly based in science, but of course, skeptics can’t (or won’t) accept that science, and would rather make this into a politcal and even personal battle. Regardless, your ad hominems on me do get a bit tiring…
ShrNfr says:
January 16, 2011 at 11:48 am
Foo on foil. Epee forever.
Real men use sabers!
On a more serious note, thank you R. Gates for the timeline on Global Warming theory development, quibbles on “theory” and “hypothesis” not withstanding. Perhaps I’ve missed this point previously, but it seems that the warming record from real thermometers as presented elswhere here hasn’t shown much, if any, acceleration in the later part of the last century, as might be expected if CO2 were a significant driver. Can you suggest a citation?
D. J. Hawkins says:
January 18, 2011 at 11:38 am
ShrNfr says:
January 16, 2011 at 11:48 am
Foo on foil. Epee forever.
Real men use sabers!
On a more serious note, thank you R. Gates for the timeline on Global Warming theory development, quibbles on “theory” and “hypothesis” not withstanding. Perhaps I’ve missed this point previously, but it seems that the warming record from real thermometers as presented elswhere here hasn’t shown much, if any, acceleration in the later part of the last century, as might be expected if CO2 were a significant driver. Can you suggest a citation?
_____
Now of course, by use of the word “real” in speaking about thermometers, or how, in general, temperatures are taken from around the globe, we of course can get into a huge discussion of these issues, but I actually am one who thinks that looking at general trends, gistemp works just fine, and I especially feel that when looking at difference between lattitudes around the globe, giss data works well. I know that this has been dicussed much here on WUWT, and many here might disagree, but I think this series of graphs:
http://data.giss.nasa.gov/gistemp/graphs/Fig.B.lrg.gif
Are very interesting, and tell us an interesting story about temps and the warming of the polar regions (especially the N. Pole). As shown in every GCM, the poles are to warm first, and this is exactly the case, with the N. Pole always to warm first and more severely at first than the S. Pole for very specific reasons that are shown by the GCM’s– namely, the huge hink sink that is the S. Ocean, and the fact that the S. Pole is covered by thousands of feet of ice, whereas the N. Pole is an ocean covered by maybe 10 feet(at the maximum) of sea ice. This represents a huge thermodynamic difference between these two regions. But, back to the point, within the bounds of naturally variability, temperatures continue to rise. 2010 is legitimately tied for the warmest year ever and was the wettest year ever (also in line with GCM models as the hydrological cycle accelerates).
What I personally look at is decade-to-decade averages, and not year to year. Will 2010-2019 be warmer than 2000-2009? Here is how I see this dyanamic shaping up to determine if this is the case. The players are:
1) The Solar Cycle
2) GHG forcing (including here both CO2 as well as the added water vapor from warming)
3) The AMO & PDO
4) Timing of the ENSO cycle
How quiet will the sun get and what will that mean to total solar irradiance, galactic cosmic rays, cloud cover, etc? Will the AMO and PDO both turn to their cold phases at the same time? How low will the Arctic Sea ice cover get and what does that mean for the extra watts/m2 in warming of that region? Will another El Nino hit about the same time as the Solar Max 24 event (no matter how weak)? In the middle of this is of course the issue of the long-term warming from the 40% rise in CO2 since the 1700’s.
This is a very exciting time to be studying all this IMO, as we are going to see first hand some very interesting dyanamics going on the next few years. Many AGW skeptics believe that there is no way that anthropogenic GHG’s could be changing the nature of either the ENSO cycle nor the PDO or AMO. I also am skeptical of this, but I would not go so far as to say there is “no way” that AGW could affect these longer-term ocean cycles. I think in the next few years, we’ll begin to get some answers about this, and really see how much stronger the solar cycle is or isn’t versus the force of AGW. Very exciting stuff!
John Johnston
Perhaps rather than natural variation it would have been clearer if I’d said random variation. The statistical significance is about testing whether there is an actual warming trend, and you’re quite right in saying it’s not making any comment about the cause of this trend, just whether or not there is a trend. But it’s not correct to say that it means “there is less than 5% chance that there has been no warming”, rather one should say “there is less than 5% chance that the observed warming is not part of a warming trend”. For instance, you could look at 2 years, 1998 and 1999, and draw a trend line between those two years, which of course would be a cooling trend since 1998 was a very warm year whilst 1999 was a significantly less warm year. But, being only two years, this trend line would have an extremely low level of statistical significance, but that wouldn’t mean that 1999 might actually have been warmer than 1998, but it would mean that the cooling from 1998 to 1999 was not part of any trend that one might expect to continue, it was just an exceptionally warm year followed by a less warm year.