Replies

52 Responses to James Hansen’s climate forecast of 1988: a whopping 150% wrong

From the comments:

**********************************************EXCERPT************************************

chicagoblack says:

June 15, 2012 at 9:10 am

Irrelevant. The Farmer’s Almanac predicted last year would be colder but it wasn’t. Modeling accuracy changes over time and improvements are obviously made just like with other measurement techniques, climate or otherwise.

****************************************************************

And

***********************************************************

RobRoy says:

June 15, 2012 at 9:25 am

chicagoblack says:
“Modelling accuracy changes over time”
Modelling inaccuracies become apparent over time. Nothing could be more relevant than showing the “Team”, then and now, cannot predict climate and have over-estimated the warming from CO2 by 150 percent.
Irrelevant? Give us a break, Dude.

*******************************************EXCERPT*****************************************

Alvin says:

June 15, 2012 at 9:33 am

@Chicagoblack

The problem is that, as with the IPCC executive summary, the findings are political in nature. We are already told that catestrophic global warming was emminent based on their finding. Now we see how far off their models were, and continue to be. Yet the finding does not change. The political is driving the scientific. Your comment “Modeling accuracy changes over time and improvements are obviously made just like with other measurement techniques, climate or otherwise.” is irrelevant. Even if the models were re-made to show 100% accuracy in hindcast and observed it would not change the political intent to fundimentally change social progress. Capitalism and the western way of life is the target.

IMHO.

CO2 emissions since 2000 to about 2.5 percent per year has increased, so that we would expect according to the Hansen paper a temperature rise, which should be stronger than in model A. Figure 1 shows the three Hansen scenarios and the real measured global temperature curve are shown. The protruding beyond Scenario A arrow represents the temperature value that the Hansen team would have predicted on the basis of a CO 2 increase of 2.5%. Be increased according to the Hansen’s forecast, the temperature would have compared to the same level in the 1970s by 1.5 ° C. In truth, however, the temperature has increased by only 0.6 ° C.

But the graph appears to show a ~0.3 degree increase (the "observed" line) 0.6 C = 1.08 F so that can't be it. Also have CO2 emissions increased by 2.5% per year? If so then Hansen was far more than 150% wrong. It appears that he said that if CO2 emissions were frozen at 2000 levels, there would be a 0.6 C increase (it appears the reporter got this prediction line confused with actual results), and that a 1.5% increase would lead to a ~1.2 C increase. I'm not sure what he meant by "constant increase," but I would guess he meant something between 0% and 1.5%. I would conservatively estimate the Hansen model would predict a 2.0 C increase in temperature for a 2.5% per year increase in CO2. But that would make him around 666% wrong, not 150%.