First of all congratulations to Martin A on a quadruple century. He is now the Joe Root of BH.

You make a very interesting point, I don't believe global warming is discussed offline, it appears that for most people it's a topic not to be touched, can't say why.

As for Arthur, I'm not sure. It may be that he is new to the argument (I won't grace it with the word "debate") and the various nuances, and assumed that someone saying it's going to get hotter and it getting hotter proves the hypothesis correct. Maybe he's unaware of previous times when it got hotter without the increase in CO2, or of the lamentable failure of the models in producing forecast of increasing heat based on Arrhenius' theory into the 21st century and being horribly wrong, or of the 0.3C forecast by the Met Office between 2004 and 2104 based on the hypothesis being not only wrong but wildly wrong. He, if it is "he", could be forgiven for all that because of the almost total news blackout on anything that in the least bit wobble the hypothesis that CO2 will cause catastrophic climate change. Perhaps he isn't aware that the world has been warming since the end of the little ice age, or that glacier retreat started before Arrhenius, or that there are glaciers advancing, who knows? We might find out if he comes back, but I doubt he will.

I do not think that people are framing the questions correctly as to whether climatology is a science. Science is an ideal that can be contrasted with a cult-like belief system. There are a number of areas that indicate to me that climatology, as it matures, is moving more towards the belief system rather a more scientific discipline.

First, a rigorous subject will seek to define the boundaries, to separate scientific statements from belief statements. How often have we seen the opposite – climatologists making statements about economics, ethics and public policy? It is an underlying assumption that doctorates in climatology (or related subjects) confer special skills or abilities, that non-“scientists” do not possess.

Second, a subject that aims to be scientific would look to what others have said about what constitutes as science. Economics certainly used to do this, looking to the philosophy of science and also to Methodology. To the extent that climatology looks at these issues it only does so to confirm the scientific status, not to recognize how the subject can become more scientific.

Third, in practice, a subject aiming to be scientific would make some distinctions that I covered a couple of years ago. These include
- Positive and Normative statements
- Trivial and non-trivial statements
- Relevant and non-relevant statements
- Good quality and poor quality evidence

Fourth, the subject has no established track record of understanding the climate system, but has plenty of excuses for failure. There is nothing positive to show movement from a set of hypotheses to real knowledge of the world derived from those hypotheses, as this recent exchange with ATTP demonstrates.

Fifth, the subject does not seek to question its assumptions about the world. For instance there is an assumption that the process of temperature homogenisation will cleanse the data of measurement biases. Logically and empirically there are issues with this assumption that a subject aiming to be a science would examine. Such examination is rejected by dogmatic and evasive means.

Martin A. If I've played any part it is that of a night watchman.

Kevin Marshall (good blog too) hit the nail on the head with the quote you gave above.

Mike J: "It's fine when spoken; not so good on the printed page."

I shall, forthwith, stop dictating my posts to Mrs geronimo.

Martin A, the one I have seen most widely quoted is from Mann in climategate email #0810:

"I gave up on Judith Curry a while ago. I don't know what she think's she's doing, but its
not helping the cause, or her professional credibility,'
mike

There are others. E.g.

Joseph Alcamo <???@usf.uni-kassel.de>
To: ???@uea.ac.uk, ???@rivm.nl
Subject: Timing, Distribution of the Statement
Date: Thu, 9 Oct 1997 18:52:33 0100
Reply-to: ???@usf.uni-kassel.de

Mike, Rob,

Sounds like you guys have been busy doing good things for the cause.

Geronimo,

you acknowledge that scientists predicted warming. And warming is what we observed.

And then you try and claim that betting on a horse is relevant to empirical assessment of a scientific claim. How so? Are you trying to argue that unless a prediction is perfectly accurate it is false? Perfect predictions are not a part of any science that I have ever known of, and error is.

Empirical assessment shows that predictions from the 80s were for warming of about 0.2/decade, and we have experienced at least 0.12/decade (RSS), or according to the surface records such as GIS more like 0.17/decade.

Arthur Johnson
In the history of Earth has
1.Has the Global Average Temperature shown a greater rate of increase than we are currently experiencing?
2.Has the Global Average Temperature Ever been greater than it is now?
3.Has Global Average Temperature ever been less than it is now?
4 Has the Global sea level been greater than it is now?
5 Has the rate of increase of Global sea level been greater than it is now?
6 Has Arctic sea ice extent been lower than it is now?
7, HAs Arctic sea ice extent been greater than it is now?
8. Has Global CO2 concentration been higher than it is now?
9. Has Global CO2 concentration been lower than it is now?
10 Is there any correlation between questions 1-7 and questions 8 and 0?

Thank you

Arthur, welcome back, we've missed you.

Arrhenius did predict warming of around 6C, which was reduced to 4C, then 3C in AR4 and now they simply don't know, or at least they won't say so in AR5.

Who said CO2 won't cause warming? As it happens there Arrhenius provided us with a formula to work out the transient climate response which shows that we should have had a transient climate response increase in temperature of 1.37K, so we're short half a degree K. Which means there's something we don't understand, or haven't taken into account.

The "predictions" coming from the climate models gave us this speech from Vickie Pope, in the last few days the Met Office have written a self-serving rebuttal, telling us that the forecast was 0.3C +/- 0.21C and claiming that this proved her prediction correct. See what she said for yourself and go figure how we'd have known the range would have been 0.09C (can they measure that?) and 0.51C. and ask yourself what good a range that wide is to policy makers. Vickie Pope's Forecast , or have look at the forecasts from the models and how they've done against reality Models v. Observations.

Go back to Feynman, if you have a hypothesis and it predicts something should happen in the physical world, and it doesn't happen, they hypothesis is wrong, no ifs and buts, wrong.

The list of failed predictions for this so-called hypothesis is a mile long.

Now here's what I, a sceptic, would do if I had a hypothesis and it proved not able to make predictions in the physical world, I'd assume had either got something wrong or there was something I didn't know.

What I most certainly wouldn't do is to use my work to inform public policy.

"Empirical assessment shows that predictions from the 80s were for warming of about 0.2/decade, and we have experienced at least 0.12/decade (RSS), or according to the surface records such as GIS more like 0.17/decade."

IPCC FAR made the first predictions for policy makers in 1990 this is what they said in the SPM.

"How quickly will global climate change?

a If emissions follow a Business-as-Usual pattern

Under the IPCC Business-as-Usual (Scenario A) emissions of greenhouse gases, the average rate of increase of global mean temperature during the next century is estimated to be about 0 3°C per decade (with an uncertainty range of 0 2°C to 0 5°C) This will result in a likely increase in global mean temperature of about 1°C above the present value (about 2°C above that in the pre-industrial period) by 2025 and 3°C above today's (about 4°C above pre-industrial) before the end of the next century.

The projected temperature rise out to the year 2100, with high, low and best-estimate climate responses, is shown in Figure 8 Because of other factors which influence climate, we would not expect the rise to be a steady one
The temperature rises shown above are realised temp- eratures, at any time we would also be committed to a further temperature rise toward the equilibrium temperature (see box "Equilibrium and Realised Climate Change") For the Ball "best-estimate" case in the year 2030, for example, a further 0 9°C rise would be expected, about 0 2°C of which would be realised by 2050 (in addition to changes due to further greenhouse gas increases), the rest would become apparent in decades or centuries

Even if we were able to stabilise emissions of each of the greenhouse gases at present day levels from now on, the temperature is predicted to rise by about 0 2°C per decade for the first few decades
The global warming will also lead to increased global average precipitation and evaporation of a few percent by 2030 Areas of sea-ice and snow are expected to diminish.

If emissions are subject to controls

Under the other IPCC emission scenarios which assume progressively increasing levels of controls, average rates of increase in global mean temperature over the next century are estimated to be about 0 2°C per decade (Scenario B), just above 0 1°C per decade (Scenario C) and about 0.1 °C per decade (Scenario D)."

We're certainly business as usual in the sense that CO2 emissions haven't abated. So their best guess was 0.3C with a lower limit of 0.2C and they got 0.17C in the RSS dataset. So it's a fail.

As a matter of interest where did you get your 0.2C from? - let me guess - there's a SkS rebuttal of the failure of the predictions? FAR was released in 1990 so was the bang up to date thinking in the scientific community, which was 0.3C for business as usual, meaning that the forecast was 0.13C out and 0.03C below the minimum forecast. Failed.

Mike Jackson. The Joseph Alcamo email was soliciting Mike Hulme and one other to get the signatures of as many scientists as possible to support the Cause - i.e. belief in dangerous human induced warming. He even says it won't matter if they're not all PhDs as no one will check.

Shortly after this I read that 2500 scientists supported the notion of CAGW, I hadn't paid any attention to the dispute but this headline put me immediately into the sceptic camp, where I've remained ever since.

geronimo

Which means there's something we don't understand, or haven't taken into account.

Don't limit yourself to a single unknown in a chaotic multi-input system.

you acknowledge that scientists predicted warming. And warming is what we observed.

Aug 11, 2015 at 3:41 AM Arthur Johnson

Getting the sign of a predicted value right, where a purely random choice would get it right with p ≃ 0.5, is not exactly a stringent test nor an unequivocal verification of a hypothesis.

"you acknowledge that scientists predicted warming. And warming is what we observed."

That's what logicians call the fallacy of "confirming the consequent".

A implies/causes B.
B is observed.
Therefore A is true.

Science instead proceeds by falsification:
A implies/causes B
B is observed not to be true.
Therefore A is not true.

The proposition 'A' is called the null hypothesis, and represents the default, pre-existing, wrong theory that your scientific advance aims to *disprove*. You make predictions based on the null hypothesis about experiments that have different outcomes for the null and the alternative, and then you make your observations. If you can reject the null hypothesis, science advances.

If you don't, then nothing happens. Failing to reject the null hypothesis doesn't mean the null hypothesis is true.

In this case, the null is that climate changes randomly, up or down. The alternative hypothesis is that it only goes up. You have to make a prediction about something on which the hypotheses differ, so simply observing that the temperature went up doesn't cut it. The null predicts that too. What you need is a stronger prediction - for example, that natural variation has a distribution in which rises longer than a certain length hardly ever happen, because being random it's unlikely to come up 'heads' ten times in a row. But you can only do that if you've got a validated model of the statistics of natural variation, which we don't. ('Validated' means 'shown empirically to reliably make sufficiently.accurate predictions for our purposes'.) The best we've got is the GCMs which all predict distributions that have been falsified. (Note, this only proves the current GCMs are wrong - it doesn't prove that CAGW isn't true.)

Until someone can exhibit a validated model of natural background climate variation, it is logically impossible to prove the AGW hypothesis. Until someone can exhibit a validated model of climate variation under the influence of CO2, it is logically impossible to disprove it either. We simply don't know. There's no evidence, one way or the other.