http://www.giss.nasa.gov/resea.....tscenario/

Carbon dioxide will become the dominant climate forcing if its emissions continue to increase and aerosol effects level off. Business-as-usual scenarios understate the potential for CO2 emission reductions from improved energy efficiency and decarbonization of fuels. Based on this potential and current CO2 growth trends, we argue that limiting the CO2 forcing increase to 1 W/m2 in the next 50 years is plausible.

Indeed, CO2 emissions from fossil fuel use declined slightly in 1998 and again in 1999, while the global economy grew. However, achieving the level of emissions needed to slow climate change significantly is likely to require policies that encourage technological developments to accelerate energy efficiency and decarbonization trends.

On the other hand, bender comments about “the proposition that Earth climate is approaching a tipping point (450ppm CO2, according to Hansen)”

Note that this is about the 450, not about bender (the poster here, not the character on Futurama) or about Hansen (the physics and astronomy guy from Iowa that runs GISS, not the band or the Idaho or Utah politicans).

Currently, at 10 ppmv per 6 years, 450 is about 36 years from now. I am of course assuming BAU and ignoring any possible increase or decrease in rates of change et al.

So we just all need to hang around until 2044.

Oh, wait, the world ends in 2012. Nevermind.

As for publishing… I do need to get off the dime and publish a few things. But there are other things about the AR(1)+white noise assumption that need to be checked. (I want to do some of the stuff I mentioned in the note to paminator.)

The distribution looks slightly skewed to the right (the way it’s done the confidence limits assumes a symetrical distribution). As the trend line is on the short side of the curve, it looks as though it falls outside of the 95% area from the middle, or to put it another way, there looks to be less than 2.5% of data to the left of the current trend line. That would put GISS and NOAA also in the falsified band.

Secondly, although (possibly for the sake of argument here) showing within 95% confidence limits, the actual measurement are so far off centre as to fall into the IPCC “very low confidence” area. What you have shown is that there is a less than 5% (maybe as low as 2-3%) chance of the Models forecast proving correct (based on current trends). Surely this should be published? Ideally before the next IPCC Report.

The plan I was thinking of was this:
1) Assume the average of the IPCC models represents the “true trend” from 1980-now. (Or 1975-now.)
2) Subtract the weather data from the “true trend”. Get the AR(1)+noise parameters.
See how that pans out.

The difficulty is that I know the parameter are a bit biased, and shorter amounts of data result in greater bias. The bias make the uncertainty intervals a little too small. So, I’m trying to figure out how to correct for the bias, which would let me use the satelitte data. But… it’s going to take a while. (I’m doing a few other tests right now.)

Perhaps also mid-troposphere absolute humidity measurements versus scenarios from GCM’s.

Great posts, by the way.

The primary problem with that craftily written paper is that lack of GCM skill inthe short-run does not in fact imply that the models does not work in the long-run. At the bottom of p. 185 he dismisses GCMs as a basis for policy-making. However, as is typical for most economists, he’s looking at short time horizons – time-scales over which GCMs were not designed to perform well*. Yet the issue is global policy over much longer time horizons

Sure. But on the other hand, the IPCC consensus projection in 1990 was 3C/century for the period one would call “about now”, and that didn’t happen. So, we are left with:
a) the only long term projections appear more or less wrong (for whatever reason)
b) more recent projection/predictions cannot be tested over the period where they are claimed to work because they are too recent. These leaves them “unproven”. and
c) Shorter term predictions aren’t looking so great. Though the comparison period is short, the deviation from the current trend is fairly large even if we account for observed variability of the earth’s surface temperatures.

None of this proves the long term projections incorrect. But, if the IPCC documents persistently tell us the ability to hindcast gives us “greater confidence” in models, then presumably, the fact that forecast ability is entirely unproven might give us “lesser confidence” in models.

So, sure the issue is over longer time horizons. (My point of view: encourage building nuclear baseload now. In terms of technology, it’s a proven way to get stable baseload now. We should also encourage research into better ways to do solar, wind etc. I’d love solar power generating shingles on my roof to run my refrigerator and TV! )

. Second, his argument is made especially easy by conveniently ignoring the proposition that Earth climate is approaching a tipping point (450ppm CO2, according to Hansen) whereupon later action will be ineffective. Note I am not saying this is correct, just that the proposition is ignored.

If the planet time constant is long, there should be time for later action. The action would need to involve geo-engineering though! (We’d need to suck out CO2 before the heat “in the pipeline” arrives, or we’d need to sprinkle aerosols in the stratosphere. Doubtless both would be expensive; in an economic journal, that’s a problem.

This refutes his impatient supposition that we should surely have the evidence in front of us by now. Yes, Earth’s climate changes, but it does so slowly relative to the economist’s and politician’s attention span. Patience, Dr. Carter.

I happen to think the preponderance of the evidence indicates AGW theory is true in the sense that a) people have added GHG’s to the atmosphere and b) it’s causing warming.

Even if the thermometer record is only 150 years, (or 5 batches of 30 years) and the temperature went “down, up, down, up, up”, that still gives general support to a theory that makes sense based on phenomena we also recognize as acting in less controversial areas. ( The “truth” of how materials — like CO2– can absorb and remmit energy has applications in combustion problems. If we didn’t recognize this physics, we’d have trouble designing furnaces! )

However, I think the models appear to have some problems. It is unfortunate that the case, as presented to the public, relies so heavily on model predictions. But, they are flashy, can create color pictures, and provide ‘projections’. So, I guess it’s natural that the climate scientists lean on that hoe.

In essence, it’s the defenders of the hockey stick handing off to guys who never get predictions right (current economic mess being a case in point) for a compound error on a (literally) global scale.

“However, as is typical for most economists, he’s looking at short time horizons – time-scales over which GCMs were not designed to perform well*”.

Bender Bob Carter is not an economist, far from it.

http://members.iinet.net.au/~glrmc/

From the biographical link above “Bob Carter is a Research Professor at James Cook University (Queensland) and the University of Adelaide (South Australia). He is a palaeontologist, stratigrapher, marine geologist and environmental scientist with more than thirty years professional experience, and holds degrees from the University of Otago (New Zealand) and the University of Cambridge (England). He has held tenured academic staff positions at the University of Otago (Dunedin) and James Cook University (Townsville), where he was Professor and Head of School of Earth Sciences between 1981 and 1999″.

As a palaeontologist & geologist Carter’s mode of thinking & framing of problems is most decidedly long term. I haven’t read the article yet but wanted to point this out to clear any misconceptions.

However one question to you. Just how long are GCM’s designed to perform well at and how sucessful have they been in performing over this time-span?

These two oversights are highly damaging to the paper’s credibility and usefulness. The author should consider a separate paper that treats these subjects a little less recklessly. Because as it stands, his argument in critically incomplete.

Looking back at the ttle of the paper, it is easy now to spot the straw man. “Where’s the evidence?” You’re not going to see it the way he’s looking at the data. You have to open your eyes.

*I’m not convinced he understands the difference between equilibrium climate sensitivity and transient climate response. The latter may be more muted than what the models suggest. That does not imply the former is equally biased. This refutes his impatient supposition that we should surely have the evidence in front of us by now. Yes, Earth’s climate changes, but it does so slowly relative to the economist’s and politician’s attention span. Patience, Dr. Carter.

It appears that Bob Carter has cited your blog in a paper:

http://www.eap-journal.com/index.html

(click on Carter’s name to download the PDF)

I predict there will soon be a huge volcano that will take your trend lines even more negative and further away from the +0.2ºC projection. This will also lead to a huge increase in variance and the +0.2ºC will once more fall within the range of plausible trends.

This will make everybody happy. Warmers will say their projection is on track and coolers will rejoice at the even larger cooling trend.

My local psychic was called away unexpectedly so I had to make the prediction myself.

It is a question of odds and what you are willing to bet based on those odds – not facts. I certaintly do not want to make huge bets on anti-CO2 policies given the current odds. That could change with another 5 years of data but that is the beauty of science: if the fact changes you can/should change your mind.

‘Don’t be absurd, I said. That’s twelve times the IPCC projected rate, it ain’t happenin, babe.

‘I knew you’d say that’ she replied, ‘it happens to be exactly the rise in the 2 years leading up to Feb 1998, the last El Nino, – we’re about due a big one, what with all these greenhouse gases building up and all .’

‘Hang on, wait a just moment’ I objected, ‘an El Nino, that’s weather, that’s not climate. The IPCC is about climate, dammit – long term trends, decades, even more.’

‘Ssshhhh’ she soothed. ‘I knew you were going to say that, some day Lucia will apply her analytical prowess to climate, not weather. I promise …..’