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The IPCC 1990 FAR predictions were wrong

Posted By Joanne Nova On May 3, 2012 @ 3:52 am In Global Warming | Comments Disabled

Have the 1990 IPCC predictions been proved completely, unarguably and utterly wrong? Yes.

They predicted that if our emissions stayed the same, temperatures would rise by 0.3 C per decade, and would be at the very least 0.2, and the most 0.5. Even by the most generous rehash of the data, the highest rate they can find is 0.18 C per decade which is likely an overestimate, and in any case, is below the very least estimate, despite the world’s emissions of CO2 continuing ever higher.

Climate Scientist Matthew England called that “very accurate”. Since when did 0.18 = 0.3? (Shall we call it “climate maths”, or just call it wrong?) The IPCC had a whole barn wall to aim at, and a battalion of government funded gold plated AK-47s to hit the target, but they still missed.

Both England and the ABC owe Minchin an apology.

The un-Skepticalscience page uses a pea and thimble trick to argue the IPCC 1990 predictions were right (“Lessons from Past Climate Predictions: IPCC FAR”). As usual John Cooks site looks  “technical” but uses complexity to hide the way they redefined the prediction in order to pretend it wasn’t wrong. Excuses excuses. Intellectual wordsmiths who bore you to death.

The un-Skepticalscience page essentially says that GHG forcing was lower than the IPCC predicted. So if you allow for the fact that the IPCC got the future concentration of CO2 wrong, then, hey, really their models are “very accurate”. Figure that estimating the concentration of atmospheric CO2 is far simpler chemistry and much less complex than getting the whole kit and caboodle of a climate model to work. If the IPCC don’t even know how big the sinks and sources of CO2 are, why would anyone trust them to get a multivariate equation with clouds, rain and ocean-turnover right?

Here’s how you can spot the pea-and-thimble trick in the un-SkepticalScience site:

1/ There is no direct quote of the IPCC prediction.

2/ The IPCC used the term “prediction” — but unskeptical science repeatedly used the term “projection”. They even retitle graphs.

3/ They didn’t use the original captions on the graphs, instead writing their own.

4/ The IPCC talked of “emissions” leading to a temperature rise. Skeptical Science talks of “radiative forcing”. (A clue, emissions are measured in gigatons, not in W/m2. The SkS page is discussing something other than the main point.)

But if you were a casual reader you wouldn’t know that unless you bothered to be skeptical, and go to the source to check.

Let’s quote the IPCC Prediction:

“If emissions follow a Business-as-usual pattern

Under the IPCC Business as Usual emissions of greenhouse gases the average rate of increase of global mean temperature during the next century is estimated to be 0.3C per decade (with an uncertainty range of 0.2C – 0.5C)” [IPCC FAR summary]

Note the wording is a prediction about “emissions” leading to warming. Radiative forcings are a subpart of the big picture, but  “Business As Usual” means emissions as usual (and for 1990), not final CO2 ppm values “as usual” or radiative forcings “as usual”. We judge the prediction by the terms they set, not post hoc ignoring the parts that fail, cherry picking something they accidentally may have got right, and then calling it all “very accurate”. It’s not even a tiny bit “accurate”. The world has been warming for 300 years, so to say it will keep warming is the most obvious forecast, and that’s what happened. The favourite horse won.

Sometimes the IPCC gets it right (accidents do happen)

The IPCC actually thought that sticking with “100% of 1990 emissions” would lead to 390ppm Co2 or so by 2012. But our emissions were 25% higher by 2012, so you’d think atmospheric CO2 would be higher too. But no, in the end result was… accidentally, 390ppm. See Fig 4 FAR summary page xvii.

Fig 4 IPCC FAR summary.  Note the words “100% 1990 emissions” which was supposed to lead to CO2 levels reaching 390ppm  by 2010. (Click to enlarge and see the 2012 prediction point marked)

Adding up the emissions of man

We emitted more than 1990 levels as usual (see here or here). You can get the idea from this graph. That should have given the IPCC a bit of a booster pushing the global temps up just that much higher.

Did human emissions stay at 1990 levels? Not so.

Man made emissions of CO2 have increased since 1990 by 25%.

Man made emissions of carbon dioxide 1990-2010

Since 1990, man-made emissions of CO2 have increased by 25%.

Data Source for the emissions graph: Tyndall Centre for Climate Change Research

Here’s the original IPCC prediction graph from the 1990 report with the original caption.

Check the wording. This graph predicts what happens if we keep emitting CO2 at the same rate.


The caption on Fig 8. IPCC FAR Summary makes it clear that the realized temperature is a prediction caused by Business-as-usual “emissions“.

Pretending that we can still call it “accurate because the IPCC overestimated how much the human emissions of CO2 would push up atmospheric levels (by underestimating global sinks) is just shifting their error.

The bottom line about climate models

In 1990 any halfwit could have drawn a straight line on a graph with a ruler through the last 100 years and come up with a prediction the Earth would warm by “about 0.15c per decade” . They’d have been more accurate than the multibillion dollar IPCC fan club, and a lot cheaper.

The models are not just a waste of money, they’re worse, because their inaccurate results are used to suck more public money into malinvestments and misconceived ideas.

The bottom line about un-SkepticalScience

The site may look superficially convincing but despite the effort to list references, they don’t quote accurately, don’t use the original headers or captions, change the words used by the IPCC, cherry pick one part of the prediction, ignore the parts that fail, and links to science articles that are essentially irrelevant. Streuth, even the name of the site is misleading.

What about other greenhouse gases?

The excuse will still come that methane did not rise as fast as predicted, which it didn’t, but it’s just another excuse. The IPCC don’t understand what drives atmospheric levels of CO2 or methane either, two accidents don’t make it accurate. And if they can’t do the basic factors there is no chance they can predict the more complex variable called “temperature”. [Click here for levels of methane, CFC's and N2O from Cape Grim]. Methane has leveled off, but conversely the accidental production of HFC-23, a greenhouse gas 11,000 times more potent than CO2, rose by 50% at the same time. The increase was so large, it offset any equivalent CO2 reductions in the whole UNFCCC Clean Development mechanism in 2007 and 2008. (see Montzka, 2008)

It’s bizarre in a way that alarmists try to defend the IPCC in 1990 or Hansen in 1988. You would think they would wear the obvious and say “models are so much better now”.  Instead, it’s telling that they think they can get away with audacious spin to say black is white, and 1.8 equals 3.


PS: There is no chance the government will pay someone to audit, check or expose the mistakes and omissions on sites that un-skeptically support big-government policies. If you think it’s useful to have more articles like the one above, perhaps you can toss a few cents in the tip jar? Every donation helps. Thanks, Jo.



Montzka, S. A., L. Kuijpers, M. O. Battle, M. Aydin, K. R. Verhulst, E. S. Saltzman, and D. W. Fahey (2010), Recent increases in global HFC-23 emissions, Geophys. Res. Lett., 37, L02808, doi:10.1029/2009GL041195.[abstract]


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