2010-09-15 13:09:48Question re Hansen 1988 predictions
John Cook

john@skepticalscience...
121.222.93.62

I wouldn't mind updating the graph on the Hansen 1988 prediction page:

 

Eg - it only goes to 2005. A skeptic objection to this is if you extend it to 2010, the discrepancy between Hansen's projections and observations are more stark. So my questions:

  • Before I reinvent the wheel, has anyone plotted Hansen's scenarios vs the latest GISS data? Unfortunately the annual figures end at 2009 - perhaps a 12 month average going right up to Aug 2010 would be good for a up-to-date comparison
  • I seem to recall reading on Real Climate that Scenario B projected CO2 emissions higher than observed while Scenario C projected CO2 emissions lower than observed. Do I remember this right?
  • I've heard somewhere that Hansen used a climate sensitivity of 2C per doubled CO2 in his 1988 paper and a climate sensitivity of 4C per doubled CO2 in his 1981 paper. Can anyone confirm this? 

BTW, here's Hansen's prediction in 1981:

 

2010-09-15 15:10:41covering it
dana1981
Dana Nuccitelli
dana1981@yahoo...
71.137.148.215

I started the Advanced rebuttal on this subject and covered a lot of those issues.  Gavin Schmidt did indeed update the temperature graph at the end of '09 (included in my rebuttal).  And the '88 paper assumed a sensitivity of 4.2°C (not sure about the '81 paper).  And the Scenario B total forcing is apparently 10% higher than reality (which I'm trying to verify in the Advanced rebuttal - CO2 was almost spot-on but other GHGs were too high in Scenario B).

Anyway, I've still got a lot of work to do on the Advanced version (right now it's basically incomprehensible because I was mostly just putting the relevant graphics in there and trying to figure out the forcing formulas, then I got sidetracked on mid-century cooling), but feel free to take a look.

2010-09-15 15:37:36Great to hear you're on the case
John Cook

john@skepticalscience...
121.222.93.62
Never mind my request and no rush on the advanced rebuttal - am happy just to hear that there is an updated version on its way. Rebuttal looks very thorough so far, look forward to it down the track.
2010-09-16 03:11:08in progress
dana1981
Dana Nuccitelli
dana1981@yahoo...
38.223.231.249
Now that the mid-century cooling is just about done, I'll be able to work on Hansen '88 this weekend.  Since I've got a pretty good start I should be able to get it done over the weekend.  The only issue is that a couple of the GHG radiative forcing formulas (like methane) turn out to be rather complex.