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Junk science: Compare IPCC predictions 20 years later

Published 15th October 2009 - 3 comments - 3661 views -


The skeptics like to compare climate models to weather forecasts. “They can’t even predict weather next week. How could they predict climate fifty years in advance? Their computer models of weather/climate behaviour are unreliable, full of errors and unknown variables.”

The manual for AGW believers replies: “Climate and weather are very different things, and the level of predictability is comparably different. Climate is defined as weather averaged over a period of time -- generally around 30 years. This averaging smooths out the random and unpredictable behaviour of weather… Seizing on meteorologists' failures to cast doubt on a climate model's 100-year projection is an argument of ignorance.”

Really? So let us see. Are climate predictions really more reliable, than weather predictions? Well, yes and no. 

In 1988 Jim Hansen was consulted by the US Senate. He made three predictions about the next 30 years of expected global warming. He predicted, that if CO2 does not have power over temperatures, the temperatures will be low. And he was right. In fact, temperatures are even lower, than he predicted. 

The lowest prediction, blue line C, was based on the assumption, that in 1990s massive reduction in CO2 atmospheric levels comes and CO2 forcing drops down. Which we did not do.

So why should we bother to decrease our "carbon footprint"? We can have cooling in spite of rising CO2 levels. It is not just a specualtion. It has already happened.



 (Fig. 1 – Hansen predictions. Bold black line is the reality. Lower than the lowest prediction. So how big is the CO2 forcing anyway?)


How to verify the greenhouse hypothesis? Easy. Just make a model and a prediction based on his model. Then wait twenty years if it comes true. 

If the greenhouse hypothesis were correct, reality would follow Hansen’s strong warming prediction in scenario A. Which would prove, that CO2 has strong forcing over temperatures.

Until 1998 his predictions seemed OK, because he just extrapolated the 1980s trend. As soon as the trend ceased, the predictions derailed. Predictions based on mechanic extrapolations… is it science at all? The 1890s extrapolations predicted, that in 2000 skies will be full of airships. 

Real scientists know, that in climate the trends never last. Climate is controlled by cycles, which go up and down and up and down. This is what we learnt from the history. From paleoclimatology. 

Now when the cooling seems to come, the warmists are less self assured. This is why we no longer hear the Green talking about “global warming”. Instead they adopted a new term – “climate change”. But predicting climate change is not a prediction at all. If you predict “something will change, it will either cool down or warm up” it is not a prediction at all. And certainly you do not need costly scientist expertise to predict that. 

It reminds me of a line from the 1930s Czech comedian Vlasta Burian: “I do not have a clue, what will happen, but you can bet I am right”. 

By the way. Is Hansen somehow related to the famous magician, clairvoyant and hypnotizer Erik Jan Hanussen (a Czech Jew), who predicted the fire of Reichstag in 1933? Or is it himself in person?



1)      Steven McIntire. Hansen update. (July 2008) [Retrieved 25 Sept 2009] Available at WWW <>  The Hansen graph is taken from here

2)      R. Pielke. Verification of IPCC 1990 predictions (Jan 2008) [Retrieved 25 Sept 2009] Available at WWW <>  There you can find IPCC predictions graph. Pretty similar to Hansen.







Category: Climate Science, | Tags: cooling, predictions, hansen,


Johannes Schmidt on 15th October 2009:

Besides the fact that Steve McIntyres post (which this post relies on) is unpublished and therefore not peer reviewed, Steve McIntyre writes: “In my opinion, there is enough autocorrelation in these series such that, statistically, the uncertainties in the trend are much wider than sometimes thought and are sufficiently wide that neither Hansen’s Scenario B (nor scenarios with lesser and greater “true” increases) can be said to be rejected - contrary to the views of many readers.”

So even the author does not want to proof that Hansen was wrong. This post promotes junk science, not Hansen’s Scenarios.

Mike on 15th October 2009:

The starting point of anthropogenic global warming is wrong. Everything else based on this starting point is also wrong.

Are we responsible for most/all of the increase in CO2 in the atmosphere?

No. We are responsible for less than 1% of the CO2 in the atmosphere. Seasonal variations show changes in CO2 concentrations 20 times greater than what man puts into the atmosphere each year. Most of the CO2 goes into the oceans and as oceans have warmed they released more CO2.

Has rising CO2 in the atmosphere contributed to most/all observed global warming?

No. CO2 levels are mostly saturated, only absorbs a narrow band of radiation and is completely swamped by water vapour by orders of magnitude. It is physically impossible for additional CO2 to cause observable warming. Oceans are responsible for warming the atmosphere, as they have 1000 times the heat capacity. A warmer atmosphere does not heat the oceans, nor melt ice. This is simply the laws of thermodynamics.

Without a valid starting point, no amount of talk, observation or action means anything.

Vitezslav Kremlik on 15th October 2009:

@ Johannes> I agree, that it is too soon to jump to conclusions. Let us wait another ten years. But it is IPCC who started the fashion to make dire predictions based on a single sunspot cycle.

For year 2009 Hansen’s predictions C and B both predict some +1°C increase. Instead we have only +0,5°C. This is a 50% difference.

The imporant thing is - for me -that this “end of warming” comes at the very time, when solar activity goes down (23 and 24th sunspot cycle are weaker).

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