This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
In 1988 Hansen predicted dire warming over the next decade and he was off by 300%. Why in the world should we listen to the same doom and gloom from him today?
Answer:
While it may well be simply ignorant repetition of misinformation in some instances, at its source, this story is a plain and simple lie.
In 1988, James Hansen testified before the US Senate on the danger of Anthropogenic Global Warming. As part of that testimony he presented a graph that was a part of a paper published soon after. This graph had three lines on it, representing three scenarios based on three projections of future emissions and volcanism. Line A was a temperature trend prediction based on rapid emissions growth and no large volcanic event and was a steep climb through year 2000 and beyond. Line B was based on modest emissions growth and one large volcanic eruption in the mid 1990's. Line C began the same as in B but with reductions in the growth of CO2 emission by the turn of the century, the result of hypothetical government controls, and also had the same volcanic eruption as scenario B.
As it happens, Mt Pinatubo did erupt in the 1990's, though early in the decade, not in the middle, and emissions have grown at a modest rate in the years since Hansen made this testimony. In other words, the forcings scenario of Line B in this graph was remarkably similar to what actually came to pass. It also just so happens that the observed temperature trend has matched very closely with the prediction represented by Line B. James Hansen was right on the money and the models he used proved successful.
(Image borrowed from Rabbet Run with much gratitude! Click here for a larger version)
Unfortunately, when Patrick Michaels made his testimony before the congress in 1998, ten years later, he saw fit to erase the two lower lines, B and C, and show the Senators only Line A. He did so so that his testimony that Hansen's predictions had been off by 300% would be believable. He lied by omission. This lie was picked up by Michael Crichton in his novel "State of Fear" (as one of many omissions, confusions and falsehood presented in that book, see this Real Climate article).
To my knowledge Patrick Michaels has never owned up to this, either with an apology and retraction or with an explanation, and consequently this urban myth continues to this day.
RabettRun has some more detail and illustrations here.
This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
"Hansen Has Been Wrong Before" was first published here, where you can still find the original comment thread. This updated version is also posted on the Grist website, where additional comments can be found, though the author, Coby Beck, does not monitor or respond there.
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This data is from Hansen at GISS[and is therefore suspect],and it does not show the dive in temperatures for 2007 and 2008.In any case temperatures are not even adherring to scenario C,let alone A and B.Just remember, Scenario C was if there was sustantial action taken worldwide to limit emissions.No such action has been taken,and the temperatures observed are still well below the line.So much for Hansen's predictions.
Posted by: Tim Wells | August 21, 2008 6:57 AM
Tim, Please open your eyes. 2007 is there, 2008 is not over so it would be a bit premature to have it! There has been no "dive" in globally and seasonally averaged temperatures, not in GISS or in CRU. The observational line is not below scenario C.
Posted by: coby | August 21, 2008 8:49 AM
Coby,please open YOUR eyes and see that the black line[Hansen's suspect GISS data]is BELOW the purple line of scenario C.If you take the more reliable Hadley centre data,the gap is even greater.And I repeat,Scenario C was the concerted,worldwide emissions abatement scenario,which has not happened.What has happened,in terms of emissions is between scenarios A and B.So why hasn't the temperature even kept track with scenario C?? When is Hansen going to admit that got it terribly wrong in 1988?
Posted by: Tim Wells | August 25, 2008 12:20 AM
Hi Tim,
I was referring to the red line, labelled "Station Data" which I believe is the GISS analysis. The black CRU, which you think is more accurate (because it is lower?), does not include the arctic where warming is predicted and observed to be much greater. Regardless, all the lines B, C, red obs and black obs are well within the range of natural variability from each other, so I don't see the utility in analysing the differences this much.
Scenario C did have hypothetical gov't controls, but not until the year 2000, so no difference is to be expected between that and B until ofter such time.
Glad we have abandoned the alleged "dive" in 2007-08.
Hansen said temperatures would rise, they have risen well within the ball park of his predictions, let's get past this erroneous talking point.
BTW, while you are taking people to task, what is your opinion on Patrick Michaels' misrepresentation to congress? Does this not warrant some outrage?
Posted by: coby | August 25, 2008 12:24 PM
Well for a start this entire graph is from Hansen and it dates from May 2007.The rest of the data for 2008 are not there.For an update to 2008 go to Climate Audit and search for Hansen,and get a complete update on recent data and Hansen's projections.One reason why Hansen's data is not reliable is because he refuses to publish his methodologies,and that is why people like Steve McIntyre are always correcting him.[Eg Hottest year 1934].The other reason is that GISS uses only Land only[red line]data and land-ocean[black line]data.GISS does not use satellite data.
"The black CRU.....does not include the arctic..."
Where did you get this from?In have never heard any such thing.
"Scenario C.....not until the year 2000."
Once again where did you get this from??I have never heard of this.But in any case,the fact is that temperatures have NOT followed Hansen's forecasts,not even for the abatement scenario.
The "dive" in 2007 and 2008 is alive and well;it is only that Hansen's graph that does not show it.Once again go to Climate audit to look at the latest satellite graph.
Re:Michaels.
Yes,Michaels should have used the full 3 scenarios and not just scenario A.That was misleading.
Posted by: Tim Wells | August 27, 2008 4:46 AM
This, to me, is one of the most fascinating parts of paying attention to climate issues. The 1934 issue is a fantastic example of McIntyre's modus operandi, as well as a great look at the way compelling misinformation picks up additional meaning, Katamari-like. Climate is an interesting field on its own, but you get the added bonus of communication, maniupulation, politics and PR thrown in for good measure!
1934 has always been a high-temp year in the data record, but only for the contiguous states, not globally. In fact, Hansen himself pointed out in 2001 that since 1998's slight nudge past 1934 was within the error bars, 1934 still had the record for US temps. (The notorious alarmist Hansen!) When McIntyre pointed out an odd blip in the data, corrections were made (not by mcIntyre) that put 1934 a touch ahead of 1998, but still within enough error range for them to remain tied. They went from tied for first place with 1998 a nose ahead to tied for first place with 1934 a nose ahead.
And keep in mind that when it came to global temperatures, 1934 is still way back there - nowhere near 1998.
But somehow this came out as McIntyre correcting Hansen. Not only that, but he did a masterful misdirection in his communication. Here's how he did it. Pay close attention.
Hansen used to go on about 1998 being the hottest year, but McIntyre pointed out an error and now 1934 is the hottest year! You don't hear Hansen talking about 1998 any more.
See the switch? It's true that Hansen talked about 1998 being the hottest year globally, but never the US temps. He specifically noted that 1934 had the record, even before McIntyre's "correction"! And so 1998 (global) gets beat out by 1934 (US), somehow. Not only that, but in the meantime, 2005 edged past 1998 in the GISS record. (And the GISS site is careful to mention that 2005 and 1998 are within the error bars of each other.) Why would anyone go on about 1998 being the hottest year if 2005 has superseded it?
McIntyre dropped the global temps down his left sleeve and pulled the US temps out of his right and all over the blogosphere you get comments like the one above. Presto!
Posted by: pough | September 2, 2008 3:22 PM
The other intersting "viral myth" is this line about "refuses to publish his methodologies". I would bet that this is just a morphing of the "Mann et al won't publish their data" wyth.
Tim, care to elaborate?
I did not answer your other points (eg "dive in 2007-08") because you simply ignored my previous response to exactly that fallacious claim. It is impossible to have a useful dialogue if you do things like that.
Posted by: coby | September 5, 2008 11:10 AM
Hey Pough,I really dont get what you are going on about.GISS admitted the error by revising their data within a couple of days of McIntrye's correction.McIntyre has never said it was global temps and niether did I.
Posted by: tim wells | September 7, 2008 6:53 AM
In any case we are getting off thread.The case in point is that Hanson's predictions are not worth the paper that they are written on.What I can not understand Coby is why you are unable to admit what is obvious.That is,all of Hanson's predictions have failed!!You can make as many excuses as you like for them,but the fact remains that temperatures have gone DOWN while CO2 levels have gone UP.The exact opposite of what Hanson predicted.
Posted by: timwells | September 19, 2008 1:54 AM
Okay, tim, this is no longer worth pursuing. In 1988 Hansen predicted .4oC rise by today via the blue line, we have observed the red and the black lines (different data sets), they are within uncertainty boundaries of each other. Yet you see the temperature going down. Who's wasting (virtual at least) paper?
Posted by: coby | September 19, 2008 5:04 PM
Coby,the graph you are referencing from is from 2007!It is out of date!No up to date data agrees with Hansen.
Posted by: timwells | September 21, 2008 3:20 AM
Why does the middle line have temperatures levelling off after 2010? also that bit about the bottom line assuming worldwide action to cut emissions. Hanson should know that even if all emissions ceased tomorrow warming would continue for decades.
Posted by: dp | September 25, 2008 11:49 AM
dp,
You'd have to check the detailed emissions scenarios Hansen et al used in that paper to know what the trajectories were.
As for continued warming after cessation of emissions, maybe that was not know at the time, or at least it was not buitl into the models. But you are correct that a complete stop to all emissions would still see the temperature rise for several decades, though leveling off, not increasingly.
Posted by: coby | September 25, 2008 3:33 PM
So coby what has caused the fall in temperatures since 2001?Hanson did not predict it,so what has been the specific cause?The sun? Aerosols?
Posted by: timwells | September 29, 2008 4:53 AM
dp, coby:
Warming continuing for decades after cessation of emissions was known (at least I knew about it, though I don't remember which papers it was from) by the time of Hansen's 1988 paper. Actually, if you'd asked scientists in the area even by the later 70s, I expect they'd have said that they expected temperatures to rise for some time after emissions stopped.
The thing more involved is that 'emissions stop' scenarios were not interesting. There has been no reason to believe that emissions would ever stop, so why bother wasting an expensive GCM run on such an implausible scenario? The answer is public, not scientific. The science already realized it'd be some time to come to equilibrium. The public has thought that as soon as we stopped making new emissions, everything would immediately return to normal (whatever that is).
Posted by: Robert Grumbine | September 29, 2008 7:35 AM
No Tim, you've got it all wrong. There hasn't been a drop since 2001. Check out the "Warming stopped in 1998" page for details. Well, I ok, there has, but only if you look at the actual data - if you smooth it by averaging over a (convenient) number of years, it levels off.
Anyone using a 7-8 year trend to suggest changes in the climate is clearly a moron. Anyone using the 20 years (at most) though from late 70s to 1998 as proof of global warming is clearly a far-sighted, hero of our times.
So they didn't predict it no, but this isn't important, as it is just a small blip in a general trend upwards. Now I know we should be proving that this general trend upwards (if it indeed exists) is due to humans, but basically we can't. We just going to assert that when the temperature goes up, it is due to human generated CO2, but when it doesn't, it's because of something else overriding the, erm, primary driver.
Posted by: paul | September 29, 2008 7:46 AM
Thanks for your comments Paul.Another question for Coby.
Coby,how would you falsify the theory of AGW?
Posted by: timwells | October 3, 2008 2:13 AM