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Discussion > Best evidence: The story so far.

rhoda

So, for the benefit of BBD, let's say it again. IF this effect is going to fry or drown us all, why can't you measure it happening? Never mind it's too little to see, we can't sort it from the noise. If it's that small, why should I worry?

The Hansen study demonstrates that a change in forcings of ~6.5W/m^2 causes and maintains the ~5C global average temperature change between the ice age (glacial) and Holocene (interglacial) climates. Small, difficult to measure changes in forcings can and do cause major climate change. Being small and difficult to measure doesn't matter here. Effectively, what you are doing is arguing from incredulity, which as I'm sure you know, is a logical fallacy.

As I have already suggested, the calculated effects of the relatively small forcing change to date from CO2 are roughly in line with the observed changes in GAT, SST, OHC and melt rates. Just as importantly, there is no other detectable and energetically sufficient forcing that could account for the observations.

HS12 shows that the relationship between CO2 forcing and T exists over very long timescales. In fact it provides the only demonstrable explanation for the general cooling over the last 50Ma.

What troubles me is the apparent need to reject this type of evidence despite its being persuasive and in the absence of any clear alternative hypothesis or evidence suggesting the need for one.

Jul 24, 2012 at 10:42 PM | Unregistered CommenterBBD

BBD - you must realise that confusing association with causation is another more material and much more prevalent fallacy when it comes to climate science - but while you are here: can you point us to any papers that show a relationship between surface temperature of the earth and satellite measurements of heat given off? It seems to me that satellites must have accumulated a pretty meaningful record by now so I would expect someone to have written something up.

Jul 24, 2012 at 10:57 PM | Registered Commentermatthu

BBD, I am not guilty of a logical fallacy because I am not trying to argue anything. I am saying 'show me'. And you can't.

Jul 24, 2012 at 11:02 PM | Registered Commenterrhoda

rhoda

Ignoring everything I say isn't helping this discussion along.

Jul 24, 2012 at 11:22 PM | Unregistered CommenterBBD

BBD - you probably missed my question.

Are you able to clarify whether satellite measurements of heat given off tell us anything about any inverse relationship between surface temperatures and heat given off - or is the record too short?

Because my understanding is that in the absence of any such relationship showing that less heat is given off as the surface of the earth warms this would tend to preclude positive feedback.

And positive feedback is a pretty vital component of CAGW is it not? Without fairly demonstrable positive feedback, well ... we can all go home, right?

Jul 24, 2012 at 11:36 PM | Registered Commentermatthu

matthu

You are trying to make a contrarian argument out of the difficulty in measuring a slight change in TOA emissivity over the last 30 years using an evolving and sparse satellite record.

But...

Being small and difficult to measure doesn't matter here. Effectively, what you are doing is arguing from incredulity, which as I'm sure you know, is a logical fallacy.

See OHC, SST, GAT, cryosphere and the Cenozoic T/CO2 relationship.

As for feedbacks, well:

If feedbacks net positive, the climate system is correspondingly sensitive to changes in forcings.

If feedbacks net neutral or negative, the climate system is correspondingly insensitive to changes in forcings.

So, how do we explain known climate variability from glacial terminations to the MWP and LIA and early C20th warming?

None were associated with a large change in forcing. Therefore, feedbacks must net positive. Otherwise, it doesn't work.

Jul 24, 2012 at 11:50 PM | Unregistered CommenterBBD

Oh, dear - you are again suggesting that simply because you cannot explain climate variability from glacial terminations to the MWP and LIA and early C20th warming this should be regarded as evidence for CO2 having an effect.

It is not evidence at all. It simply exposes lack of knowledge. Not the same thing.

Fortunately, we do have 20 years of satellite measurements to help us. And you know what? the relationship between surface temperature and heat given off by the earth has the opposite slope to what is predicted by all of the climate models.

Fancy that. Now that really is evidence. Not the evidence you wanted - but evidence all the same.

Jul 25, 2012 at 12:02 AM | Registered Commentermatthu

What I need to understand is how climate works if feedbacks aren't positive. You didn't say.

Jul 25, 2012 at 12:08 AM | Unregistered CommenterBBD

"...slight change in TOA emissivity over the last 30 years using an evolving and sparse satellite record."

What do you think we are saying?

Jul 25, 2012 at 2:17 AM | Registered Commentershub

What I need to understand is how climate works if feedbacks aren't positive. You didn't say.

I am not the one saying that the science is settled - I believe that's what others have said. I'm the one still looking for evidence, remember?

I also think it is particularly foolish to be considering only a single explanation at this stage when the evidence does not stack up - even after all of this effort and wasteful expenditure. I would feel a whole lot more confident if an equal amount of money (but possibly a lot less overall) was spent considering alternative explanations.

Jul 25, 2012 at 6:32 AM | Registered Commentermatthu

"What I need to understand is how climate works if feedbacks aren't positive. You didn't say."

If feedbacks are negative the theory is the climate would warm, more evaporated water would cause clouds and the planet would cool because of albedo. A kind of cyclical thing where you'd get a Minoan Warm period, followed by a colder earth reducing clouds, followed by a Roman Warm period followed by a cold dark ages, followed by a Mediaeval Warm Perion, followed by a Little Ice Age, followed by warming.

But there doesn't appear to be any evidence to support this theory.

You may have given it to me already, but I am failing to understand why Conservation of Heat would be the cause of the capping of the positive feedback at 3.5C

Jul 25, 2012 at 7:56 AM | Unregistered Commentergeronimo

Re: Jul 25, 2012 at 12:02 AM | matthu

"Fortunately, we do have 20 years of satellite measurements to help us. And you know what? the relationship between surface temperature and heat given off by the earth has the opposite slope to what is predicted by all of the climate models."

It's one of my favourite images, matthu, the satellite measurement slope going one way and all eleven of the climate models going the other!!!, wonderful, - but of course, as to be expected, hotly disputed by the IPCC alarmists.

One wonders how many other parameters could similarly be displayed to be faulty in a models vs reality showdown..

Jul 25, 2012 at 7:59 AM | Unregistered CommenterMarion

rhoda, like BBD I have no idea why you'd be suspicious of papers produced by Hansen, albeit he's a known activist who told us West Manhattan would be under water by 2008, he is an archivist of the highest probity. Take a look at his work here:

http://stevengoddard.wordpress.com/2012/06/11/why-hansen-had-to-corrupt-the-temperature-record/#comment-96146

Jul 25, 2012 at 8:03 AM | Unregistered Commentergeronimo

Re: Jul 25, 2012 at 7:56 AM | geronimo

Don't you know - they don't accept 'reality' as evidence, it has to come from models.

But whoops....what's this....new 'evidence' just in .... and guess what -

it seems that the Climate models have overestimated positive feedback and underestimated negative feedback.

What a surprise!!!

http://pielkeclimatesci.wordpress.com/2012/07/16/new-paper-weather-and-climate-analyses-using-improved-global-water-vapor-observations-by-vonder-haar-et-al-2012/

Jul 25, 2012 at 8:21 AM | Unregistered CommenterMarion

Rhoda, here are some quotes from famous scientists emphasising your point:

"If you can't explain something simply, you don't know enough about it."

Albert Einstein

"You do not really understand something unless you can explain it to your grandmother."

Albert Einstein

"If you can't explain your theory to a barmaid it probably isn't very good physics."

Ernest Rutherford

Warmists please note.

Jul 25, 2012 at 8:59 AM | Unregistered Commentergeronimo

One of the papers which Richard referred me to contained the following in its conclusions:

We found that daily Ld increased at an
average rate of 2.2 W m2 per decade from 1973 to 2008.
The increase in Ld is mainly due to the increase in air
temperature, water vapor and CO2 concentration.

"Global atmospheric downward longwave radiation over land surface
under all-sky conditions from 1973 to 2008
Kaicun Wang1 and Shunlin Liang1
Received 25 January 2009; revised 24 June 2009; accepted 2 July 2009; published 1 October 2009."

So why is temperature not rising? CO2 concentrations are still rising. According to (restricted to Spainish conditions) clouds cover is shrinking.

Jul 25, 2012 at 1:22 PM | Registered CommenterDung

Didn't Wang and Liang rely on models for their base levels? They did not seem, to me, to be comparing actual data over time.

Jul 25, 2012 at 1:32 PM | Registered Commenterrhoda

Rhoda

Sorry, I found the body of the work a bit over my head and so only read the conclusions ^.^

Jul 25, 2012 at 1:37 PM | Registered CommenterDung

Let's not forget the hotspot that should be directly measurable.

Climate scientists claim that warming due to CO2 will likely cause more evaporation from the oceans and that this extra water vapour will in turn lead to more heat being trapped (water vapour being the main greenhouse gas) and this extra heat will cause even more evaporation and so on. By this argument up to two thirds of projected temperature increases will in fact be due to amplification by feedbacks.

Other scientists argue that any feedbacks may turn out to be inconsequential or may even act as a dampener reducing the effect of any warming.

Which group are closer to the truth?

Climate scientists who advocate a large positive feedback predict that the extra water vapour produced by evaporation will push the warmer wetter lower troposphere up into volume previously occupied by cool dry air.

This effect should be directly observable and measureable as a hotspot in the atmosphere – but the corollary of this is that the absence of any such hotspot would contradict this theory i.e. no observable hotspot, no extra water vapour produced by evaporation: no extra water vapour produced by evaporation, no positive amplification.

Well guess what? Despite millions of weather balloons having built up a good picture of atmospheric temperatures stretching back over fifty years no-one has yet detected a hotspot, not even a small one. So by this measure (and not for want of trying) there has been no amplification of temperatures over a period that includes the seventies, eighties and nineties when warming has been greatest.

Jul 25, 2012 at 2:34 PM | Registered Commentermatthu

Matthu

Oh for the memory I had 40 years ago! I had forgotten that fact even though I wrote to Ed Miliband and Chris Huhne about it ^.^

Jul 25, 2012 at 3:48 PM | Registered CommenterDung

matthu

Other scientists argue that any feedbacks may turn out to be inconsequential or may even act as a dampener reducing the effect of any warming.

This is just blatant misrepresentation. The mainstream scientific position is that WV will be a major amplifier of CO2 forcing. Virtually everyone accepts this. You are creating a completely false impression that there exists a significant debate about this. Apart from the completely rejected hypotheses of Lindzen and Spencer (accepted by exactly nobody), there is no debate.

I can't escape the suspicion that you haven't understood quite how impossible it would be for known climate behaviour to occur if feedbacks were negative or neutral. This goes for one or two others here. A sort of mixture of incomprehension and denial.

Jul 25, 2012 at 6:27 PM | Unregistered CommenterBBD

BBD, the comment by matthu seems to me more understandable and less eruptive, for instance, and less cloudy or hotly also. Again, let us consider if you misrepresent, perhaps even significantly: Can we agree on the lowest common denominators, for instance: 'to argue' ≠ (by all means) 'a debate'?

Jul 25, 2012 at 7:15 PM | Unregistered CommenterSeptember 2011

BBD

You make posts that I do not understand and reference papers some of which are over my head but you also make comments that can be disproved.

The mainstream scientific position is that WV will be a major amplifier of CO2 forcing. Virtually everyone accepts this.
This is one of those comments.

Even the IPCC reports gave water vapour error margins that included negative feedback.

Jul 25, 2012 at 7:23 PM | Registered CommenterDung

"...mainstream scientific position ...'

As if this guy went to every climate scientist's house and had dinner with them and found out what they think about water vapour.

"The mainstream scientific position is that WV will be a major amplifier of CO2 forcing."

That's fine. Just as long as it hasn't already done anything measurable yet.

Even I hold such positions: "something, something, something is going to be really big, yeah, ok".

Jul 25, 2012 at 7:38 PM | Registered Commentershub

The mainstream scientific position is that WV will be a major amplifier of CO2 forcing. Virtually everyone accepts this.
I think you're over-egging the pudding a bit, BBD. The mainstream position is certainly that water vapour will increase and so per se will give positive feedback but the extent to which it does is not as clear cut as you make out and there is a coherent body of opinion that argues that the increased cloud cover which will result may well have a cooling effect.
So the amplifying effect on the 1.2C per doubling of CO2 may be considerably less than the extreme position taken up by some of your pals. This science is by no means even close to being settled yet.

Jul 25, 2012 at 8:07 PM | Registered CommenterMike Jackson