If you look at the Wikipedia plot

http://en.wikipedia.org/wiki/File:Temp-sunspot-co2.svg

The splice is where the smooth line joins the jagged line.

Scroll further down the page,

Click on 1 (light blue) Law Dome CO2 Data: ftp://ftp.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/law/law_co2.txt

This gives you the Law Dome data you could plot in Excel (or anywhere).

Click on 2 (blue) Mauna Loa CO2 data:http://www.esrl.noaa.gov/gmd/ccgg/trends/co2_mm_mlo.dat

This gives you the Mauna Loa data that can also be plotted in Excel

These are EXACTLY the spin-up datasets that are used to get the IPCC GCM’s into “equilibrium” before simulations commence (ACO2 “hard-wiring”, although Gareth Renowden disputes this – without basis I suspect ).

As I described up-thread, you can easily compute Hansens CO2 forcing in the models by external calculation using that data:

http://www.climateconversation.wordshine.co.nz/2010/09/new-unfccc-climate-chief-no-worse-than-the-old/#comment-24527

“However, how does this invalidate the CAGW argument?”

Simple, if either of these datasets are used to calculate CO2 forcing independent of the other, whether in models or by external calculation you can do yourself – the results will be gibberish. Obviously both sets would have to be extended to do so; Law Dome forward; Mauna Loa backward (not sure if the data exists). So obviously a calculation for year 2000 say, using Law Dome data (if it exists) will not yield the same figure that results from using Mauna Loa ppm value for that year.

Similarly, a calculation for 1940 using Mauna Loa ppm value for that year (if it exists) will not yield the same value that results from using Law Dome ppm value for that year.

“It does seem like a somewhat different issue to the “nature trick” data splice.”

Not that different at all, just that nothing is hidden, but they are disparate datasets just the same as the “nature trick” data splice in order to achieve the desired up-tick – you’ve been conned.

However, how does this invalidate the CAGW argument?

It does seem like a somewhat different issue to the “nature trick” data splice.

We basically have three groups in the debate – warmists (e.g.RealClimate, Hot Topic), luke-warmists (e.g. Anthony Watts) and hard-core sceptics (e.g. Hockey Schtick, C3). I’ll declare now that I am to the right of the last group and yes that is possible as I will describe.

You will not see many graphs and plots such as those put up by Richard Treadgold in his post above at warmist sites (they specialize in textual debate – hide the evidence) for obvious reasons but you will see pages of them at luke-warm and hard-core sites again for obvious reasons.

Anyone seriously entering the debate should by now be able to recognize (I like zeds, RT, zzzzz) instantly the shape of the Law Dome – Mauna Loa CO2 dataset splice whenever it turns up in a graph being viewed. If you can’t, you’re not serious and you don’t know what you are talking about and it doesn’t matter whether you have a Ph.D or not.

Here’s the the CO2 historical spliced dataset in blue (ignore the temperature and sunspots):-

http://en.wikipedia.org/wiki/File:Temp-sunspot-co2.svg

What is lamentable to me is the misrepresentation of this splice even at hard-core sites because what happens is that the distinction between the 2 datasets in the splice is removed and what is left is 1 contiguous line and the join is indistinguishable to all but the discerning e.g. from the hard-core C3 site:-

http://c3headlines.typepad.com/.a/6a010536b58035970c01348887ea36970c-pi

Yup, same data, different presentation.

If either of these 2 datasets had been used over the years instead of the splice, whether in models or elsewhere, the warmist CAGW case would be instantly NULL and we would not be having this discussion.

Not just warmists (I know it exists), there’s programs underway that measure LWIR back radiation – BSRN for example

http://www.climateconversation.wordshine.co.nz/open-threads/climate/climate-science/atmosphere/#comment-28093

The problem for warmists is that the heating ability of solar SWIR is spent once it is reflected and the wave-length changes to LWIR. Also the offending 1.7Wm2 of CO2 is totally insignificant in the context of 400Wm2 total LWIR back radiation.

“and it does not exist then what happens to computer model projections; are they doubled or what?”

The GHG’s do re-radiate energy but now you are getting to the core contentious debate. The warmists (Hansen predominately) make CO2 the major climate driver so the models are hard wired accordingly. This is the “circular reasoning” we are hearing everywhere. As Dr Roy Spencer says:-

“After assuming clouds and water vapor are no more than feedbacks upon temperature, the Lacis et al. paper then uses a climate model experiment to ‘prove’ their paradigm that CO2 drives climate — by forcing the model with a CO2 change, resulting in a large temperature response!

Well, DUH. If they had forced the model with a water vapor change, it would have done the same thing. Or a cloud change. But they had already assumed water vapor and clouds cannot be climate drivers.”

http://www.drroyspencer.com/2010/10/does-co2-drive-the-earths-climate-system-comments-on-the-latest-nasa-giss-paper/

You can easily compute Hansens CO2 forcing in the models by external calculation here:

http://www.climateconversation.wordshine.co.nz/2010/09/new-unfccc-climate-chief-no-worse-than-the-old/#comment-24527

There’s also the little matter of the hockey stick spliced spin-up datasets – that’s the biggest model illusion, the Mauna Loa set provides the uptick for 80′s-90′s warming – pity there’s been no warming last decade though.

Anyway, I am not denying that the climate is changing (it always has), or that the world is warming (although the temperature records appear to be a bit dodgy). I can even accept that CO2 may have a role in that, possibly minor.

What I do doubt are the alarming prognostications of the IPCC and the climate change lobby groups.

I prefer the term “climate realist”.