Can anyone answer a simple question for me?

If as I understand it, global temperatures fell strongly in 2007, and that fall has continued into 2008, if those temperatures keep falling, say to over 2C less than in 1980, isnt that the end of the AGW theory? Surely whatever it is they predict, a sharp fall in temperatures would be outside those bounds. Measurements outside of those bounds, and the AGW game is up?

It looks to me as if the measurements that we have for the past 18 months suggest that it is almost over for AGW as a scientific hypothesis. Our governments should be spending money on snow ploughs, not carbon trading.

From what I read about Solar Activity being almost zero at the moment, if the alternative ‘Solar’ theory is right, things are going to get pretty chilly over the next couple of years.

I sent an email to Greenpeace to ask them if they would be changing their policy on climate change given the recent falls in global temperatures. I received a very rude response. It is interesting just how many vested interests in all of this have been built up over the years. Should the evidence prove that the King has no clothes, the little boy who points this out is going to receive a very rough time from the courtiers of the King until opinion changes decisively.

Thanks for listening to an amateur.

When in the past increased temp caused increased CO2, much of that increase in CO2 came via outgassing from warmer oceans. But we know that right now, CO2 in the oceans is increasing, not decreasing – net CO2 flow is from atmosphere to ocean, not out of ocean. This is causing ocean acidification, and it is another serious risk that comes with rapidly increased atmospheric CO2.
Interesting, Ice. AGW physics again? Funny how, with AGW, the laws of nature can suddenly, magically be reversed. If C02 in the oceans is indeed increasing, it couldn’t possibly be because the oceans have started to cool, could it? Or, possibly due to increased underwater volcanic activity?

So, what happens if you don’t add the feed back in the models?
From what I understand, the postive feedback amplifier is 2.5
“As just mentioned, a doubling of the concentration of carbon dioxide (from the pre-Industrial value of 280 parts per million) in the global atmosphere causes a forcing of 4 W/m2. The central value of the climate sensitivity to this change is a global average temperature increase of 3 °C (5.4 °F), but with a range from 1.5 °C to 4.5 °C (2.7 to 8.1 °F) (based on climate system models: see section 4). The central value of 3 °C is an amplification by a factor of 2.5 over the direct effect of 1.2 °C (2.2 °F). Well-documented climate changes during the history of Earth, especially the changes between the last major ice age (20,000 years ago) and the current warm period, imply that the climate sensitivity is near the 3 °C value. However, the true climate sensitivity remains uncertain, in part because it is difficult to model the effect of feedback. In particular, the magnitude and even the sign of the feedback can differ according to the composition, thickness, and altitude of the clouds, and some studies have suggested a lesser climate sensitivity.”

Climate Change Science: An Analysis of Some Key Questions, pp 6-7,
Committee on the Science of Climate Change
National Research Council
In other words the amplification factor of 2.5 is an assumption made to “balance the books”
So again, I ask the what has been the ampiification factor over the last eight years?
Ophiuchus
I have no idea what caused the climate change from MWP to LIA, but I’m 99.9%confident that mankind didn’t cause it. I guess we can chock it up to unknow factors.

I think Paul Clark made the good point about there being several stances on this subject and by doing so, pointed out that there are levels of scepticism. I’d side with the 0.1-1 view that there is a limited affect, but nothing apocalyptic on the cards. I think the ‘end of the world’ scenario is the one the media hypes (it’s good story after all!) and is the one which many readers/posters here have the biggest disagreement with.

They are given ‘equal modeling.” All of those known effects are included in the models. Solar output, as TSI, is included – but TSI trend has been flat for 50 years now. Ocean effects such as El Nino adn La Nina come out of the models. Yes,many of the models produce El Nino and La Nina events, or something very like them. In any case, these are not forcings, they are redistributions of heat within the earth system.

And finally the standard experiment includes a control. It is relatively easy to build a random model to compare with all the other hypothesized models that should be getting equal treatment from the scientific community engaged in this model experiment.”
One control that is frequently done, is to run the models without an anthropogenic CO2 input. The models have parameterizations or ranges of inputs – places where our measurements constrain a range of physically rel values, not a precise value. Modelers have tried to play with these parameterizations and values in a no-anthropogenic-CO2 model, to get the rise in temps over the last century – and uniformly failed. The ONLY way to get model output for the coupled GCMs that matches the temperature increase of the last century, is to include anthropogenic CO2 as an input. The anthro CO2 then operates through basic radiative physics and feedbacks, such that it is very easy to use physically realistic values for all parameters adn settings, and reproduce the temperatures of the last cnetury.

This is actually incorrect. Basic radiative physics says that the equilibrium response to 2xCO2 will be a temperature increase of 1.1C. This is the baseline, the prediction from ‘basic physics,’ in the absence of any feedbacks.

“What Hansen and the IPCC seem to be saying is that there is positive feedback but currently damped by negative feedback. A “Tipping point” in his definition would be a point where the negative feedback is swamped (akin to walking off a cliff).”
No, this is not what Hansen and IPCC are saying. That is not how they claim positive and negative feedbacks work. A positive feedback with a gain of less than unity, is expected to cause an equilibrium temperature response of about 3C per 2xCO2. Less than unity gain is not a ‘negative feedback.’ A “tipping point” is not a point of runaway warming – it is a point at which we commit to a new temperature regime, perhaps a new warmer stable state, from which it will be very difficult or impossible to recover. Hansen is specifically referring to such things a permafrost melt and methane liberation, or arctic sea ice melt and its effect on Greenland ice melt, along with separate WAIS ice melt, and their effects on sea level and on increasing the speed of approach of the equilibirium warming, when he refers to a ‘tipping point.’

I also see several people above speculating that increasing temperatures right now are causing increased CO2. This is not possible. When in the past increased temp caused increased CO2, much of that increase in CO2 came via outgassing from warmer oceans. But we know that right now, CO2 in the oceans is increasing, not decreasing – net CO2 flow is from atmosphere to ocean, not out of ocean. This is causing ocean acidification, and it is another serious risk that comes with rapidly increased atmospheric CO2. We also see the signatures of CO2 coming from combustion of fossil fuels, in the isotope composition of atmospheric CO2, and in the decrease in atmospheric O2 .

OK, Dav, so you are offering as a hypothesis

Oh, stop already! I’m not offering that as an hypothesis — it’s already assumed in every hypothesis test!!!!

My point, that you’ve missed (deliberately?) is that natural causes explain more than AGW therefore, all the AGW-ers need to go back to the drawing board. In case, you don’t know (something I’m coming to believe more and more) “natural causes” is synonymous with “unknown.” Yes, indeed, UNKOWN CAUSES are a far better explanation for the present climate than AGW.

You really need to read what others are saying far more carefully than you are evidencing and avoid misquoting or representing what is said. Doing so is not going to be lost on the rest of us and will eventually relegate you to the dumb-dumb category. If you think you’re accomplishing anything else then you are wrong.

Of course, you may just be a bumbling troll that gets jollies out of being perverse. If so, you need to look up a guy posting as TCO on other sites. He’s a real pro and I’m sure he’ll be happy to give you pointers, maybe even OJT.

“Natural causes (something other than AGW) caused the increase in temperature since the mid-18th century.”

whereas my hypothesis is:

“AGW caused most of the increase in temperature since the mid-19th century.”

You list a bunch of facts. I’ll first point out that you’ve left out a few crucial facts (I’ll raise those later), but I’ll agree with all your facts except one: that temperatures in the Southern Hemisphere have been going down. I think you’ve gotten some bad data there. Fortunately, it’s not crucial to either of our cases.

The real problem with your analysis is that your framing of the hypothesis leads to useless predictions. Among the predictions that you attribute to your hypothesis are:

temperatures will vary
CO2 will vary

Well, yes, I agree, temperatures will vary — but that’s not much of a prediction. And it really isn’t saying anything to declare that CO2 concentrations will vary. So what?

The AGW hypothesis makes a prediction that temperatures will rise and right there in the middle of your facts list is the statement “temperatures have been rising since the mid 1700’s”

So you seem to be arguing that the AGW hypothesis correctly explains the observations and that a bland say-nothing hypothesis also correctly explains the observations.

But then you turn around and write this:

AGW has hardly been shown better than all other hypotheses. In fact, since it can’t be shown to accurately predict the future, it’s next to worthless.

The other hypothesis that you list makes only the non-prediction that temperatures will vary, whereas AGW predicts temperature rise. And yet you say that AGW has not been shown to be better than your hypothesis?!?!?

Look, if you’ve got some other hypothesis in your back pocket, let’s see it. But I’ll engage in some speculative anticipation. You seem to be blundering around the idea that there’s some magic “unknown explanation” that we should give credence to. As I have explained at length, that’s not how the scientific method works. If you have an idea for an explanation, write it up as a formal hypothesis and we can examine it. But if you truly are claiming that we should accept the “it’s a mystery” explanation, then all I can do is refer you back to my long description of the scientific method.

Mike C writes:

Ophi, I specificly mentioned ENSO, Volcanoes and Solar as natural variations. They are the 3 majors, you can start with them.

I cannot find any such reference in your postings. Could you give me a time index for the statement to which you refer? Even better, I’d appreciate it if you could gather together the bits and pieces and restate your question as a single unit.

What do you estimate the climate sensitivity (’C change) for doubling of CO2 to be? The options seem to be:

0: No effect at all
0.1-1.0: Some effect, as predicted by basic physics
1.0-3.0: Effect with positive feedback, as proposed by IPCC
3.0-6.0: Effect with tipping point, as proposed by Hansen et al.</blockquote

It has to be #2. #1 is extremely unlikely and doesn’t correspond to the physics. Systems analysis tells us that positive feedback automatically implies an instant tipping point.

What Hansen and the IPCC seem to be saying is that there is positive feedback but currently damped by negative feedback. A “Tipping point” in his definition would be a point where the negative feedback is swamped (akin to walking off a cliff).

The problem is that runaway positive feedbacks in nature rarely happen. Positive feedback is synonymous with amplification. Most, if not all, naturally occurring positive feedbacks (e.g., explosives) require internal energy release. All other naturally occurring feedbacks are simply apparent and are without energy gain, e.g., gravity “amplifies” the velocity of a dropped object without end (except for physical contact) by exchanging potential energy for kinetic energy. A lever “amplifies” force but really the effect of differing torques from differing arm lengths.

While it’s possible (even likely) that additional heat retained by addition CO2 will increase water vapor content (a type of “positive” feedback), there is still an upper limit to how much additional water vapor can be added.

Things to consider: Water vapor quickly condenses out of the air. Increasing insulation (which is what a GHG is essentially), has diminishing return (a logarithmic response). This logarithmic response implies negative feedback. Also, since added CO2 itself has a logarithmic response, it’s effect on increasing water vapor is also logarithmic making the net response to added CO2 proportional to log log dCO2.

Considering the very apparent political stance of Hansen, it’s nearly impossible to tell if he actually believes what he’s saying or if it’s calculated BS.

What would replace AGW if it doesn’t work? “Something else” aka “natural causes.” In drug testing, a control group is used to proxy the result of doing nothing at all, i.e., allowing nature to take its course. In climate hypothesis testing, there is no genuine control group. Instead the past is used as a proxy. Unfortunately, that adds other variables making it very difficult to determine what conditions would exist without the presence of humans.

So, how does one go about comparing hypotheses? I don’t know about you but I need to look at how well the hypothesis predicts (and/or “explains” i.e. predicts the past). If it can’t predict at all it’s totally worthless. What do we have? I might also point out that without being able to predict the future, any hypothesis is of questionable value.

Facts:
o adding CO2 causes temperature rise
o CO2 varied in the past in periods extending over centuries
o Temperature varied in the past
o CO2 and temperature were correlated
o this occurred before human technology
o CO2 rises lag temperature (implies: temperature rise causes CO2 rise)
o there was a warm period during medieval times that was likely warmer than today. (historic evidence, grapes grown in England, etc.)

present (and a bit before)
o there was a “Little Ice Age” bottoming around mid-1700′s
o temperatures have been rising since the mid 1700′s
o CO2 has been monotonically rising
o temperatures have risen and fallen with an apparent long term trend of rising
o majority of temperature rise has been in Northern Hemisphere
o added CO2 is assumed to mix evenly in the atmosphere thus it’s measured at only a few points on the Earth
o decreasing SH temperatures while increasing NH temperatures contradicts
o the majority of the anthropogenic CO2 was added post-1940
o 1940 marks the beginning of a 40 year cooling trend (one that even led James Hansen to a global cooling alarm)

Predictions by hypothesis:

Natural causes
there is no reason to assume that past causes no longer exist therefore
- temperatures will vary
o CO2 will vary
o temperatures will rise as CO2 rises
o CO2 will increase as temperatures rise
o temperatures and CO2 will be loosely correlated

AGW
o CO2 added from humans will cause temperatures to rise
o temperatures and CO2 will be loosely correlated
o unless humans change CO2 can only rise

As I see it, the only prediction by AGW is “it’s been shown that adding CO2 causes temperatures to rise.” IOW: humans affect temperatures by simply breathing. it “explains” at best one fact. And this fact is also predicted/explained by natural causes. Natural causes, OTOH, explain all facts. Neither hypothesis can accurately predict the future.

AGW has hardly been shown better than all other hypotheses. In fact, since it can’t be shown to accurately predict the future, it’s next to worthless.

OK. Maybe I understand where you’re coming from a little better but I think you’ve misinterpreted what I’ve been asking.

Yes, if there are two hypotheses, A and B, they can be compared. What is often forgotten, and I think this is true for you, is there is always a third possibility: something else. I believe you have forgotten this because you’ve more or less said that, lacking a better hypothesis, AGW wins. It is you who is more prone to binary thinking IMO.

The problem here may be more similar to drug testing where there is only one drug under consideration. In such a test, the question is: does the drug have a significant effect? The understood other is: administering nothing at all. The problem with testing AGW is the lack of a control group for comparison.

Still though, the question remains: is AGW a viable hypothesis? A better question is: “would the climate be the same if humans weren’t here?” Another phrasing: “do humans have a significant effect?”

(continued in a later post)

The Reason: The short period we are studying is very noisy as are all periods of temperature. An overall first order trend line in the last 100 years that has predictive value is a weak proof, given the nature of past fluctuations, and I believe you must consider past fluctuations in your climate model, just in case those circumstances happen again. While modeling is far more complicated than linear fit, it too will have poor predictive value -and odds- that one would place bets on if it were a horse race. Its as if the AGW scientists have secret gnostic information that all causes in the past are over (even though they admit to not understanding the mechanisms), or are now somehow far less of a factor, so CO2 has to be it and our temperature will rise as CO2 rises.

The Thorn: There are other measures that show equal and even greater correlation to temperature than CO2, even though we don’t understand the exact mechanisms. The Sun’s output cyclically correlates very well with temperature fluctuation and gets even tighter with oceanic temperature swings.

My Main Complaint: Finally, the historical record demonstrates just as many correlations for solar forcing or oceanic forcing, or the combination, as it does CO2. So why aren’t these given equal modeling? And finally the standard experiment includes a control. It is relatively easy to build a random model to compare with all the other hypothesized models that should be getting equal treatment from the scientific community engaged in this model experiment.

Wanna Bet On It? The betting community is missing out on a great long term investment. They should convince the modelers to produce several competing models, including random, and then put it out there for the public to place bets on. I would spread my bet around all models that include solar forcing as the primary factor, with oceanic cycles as secondary.