Thursday, April 13, 2006

RTFR (I)



UPDATE: For those coming in from various places we have posted an update on 1988 and all that for those who want to look behind the thick black RSS line, and there is a whole series of Rabett Run posts, perhaps the most relevant of which is No More Mr. Nice Bunny where Jim Hansen shows the rubes the trick (esp. if you are reading Climate Audit). Well Lookee That and Business as Usual in 1988 are also worth a look. You can find more of these by searching this blog on "1988"

A rather strange push back has developed centering around Jim Hansen's Congressional testimony in 1988. In that testimony he presented a graph with three scenarios which he labeled A, B, C, and predictions of global temperature based on each of these scenarios


In 1998, Patrick Michaels in testimony before congress, also presented this graph, but erased scenarios B and C. He claimed that,

That model predicted that global temperature between 1988 and 1997 would rise by 0.45°C (Figure 1). Figure 2 compares this to the observed temperature changes from three independent sources. Ground-based temperatures from the IPCC show a rise of 0.11°C, or more than four times less than Hansen predicted. Lower atmosphere temperatures measured by ascending thermistors on weather balloons show a decline of 0.36°C and satellites measuring the same layer (our only truly global measure) showed a decline of 0.24°C.
The statements about satellite and weather balloon measurements have now been shown to "inoperative" (e.g. wrong, they are now are calculated to be consistent with surface measurements )**. Hansen was a mite peeved at Pat's erasing. He has put his take on this and other acts of denial on the GISS site.

However, a bunch of very strange spaghetti is being thrown against the wall with respect to Hansen's 1988 testimony and the paper upon which the testimony was based (J. Geophys. Res. 93 (8) 9341-9364 (1988). Some of them are very simple to deal with, others are more complex. Finally, I do want to check in the Library of Congress to see if the written and oral testimony is available.

Eli was able to find the abstract for this paper at GISS, and posted it into the maelstrom at R Pielke's place (towards the bottom) where he has become an unfavorite for pointing out that the Emperor is wearing some interesting togs. One of the weird claims was that Hansen had never said that Scenario B was the most probable in his testimony or in the abstract. This was a VERY serious issue for Paul, just Paul. To which we say RTFR (p9345 2nd paragraph)
These scenarios are designed to yield sensitivity experiments for a broad range of future greenhouse forcings. Scenario A, since it is exponential, must eventually be on the high side of reality in view of finite resource constraints and environmental concerns, even though the growth of emissions in scenario A (~1.5%/yr) is less than the rate typical of the past century (~4%/yr). Scenario C is a more drastic curtailment of emissions than has generally been imagined; it represents elimination of cholorfluorocarbon emissions by 2000 and reduction of CO2 and other trace gas emissions to a level such that the annual growth rates are zero (i.e. the sources just balance the sinks) by the year 2000. Scenario B is perhaps the most plausible of the three cases.
2. But wait, there is even more amusement in the comments, one of the Ethonettes, Jim Clarke (in reference to the very warm El Nino year 1998, where the global temperature was so high that we are just reaching it again ) said:
I would also like to point out that you will not find a 7 year period of 'flat' temperatures in any of Hansen's forecasts with increasing CO2. Even with ENSO cycles, his graphs show a net warming over any seven year period.
Actually you can, the period between 1974 and 1982 in Scenarios B and C. But there is a VERY interesting little wrinkle in Scenario A. I've taken the liberty of isolating Scenario A between about 1995 and 2005

[insert tongue in cheek] As you can see, the GISS model found the 1998 Super El Nino, ten years before it occurred, and as you can see, in this exponential forcing model it took five years for the temperature to exceed the global temperature in the Super El Nino year. Another triumph for GCMs!


**an important point to remember is that the satellite does not measure temperature directly, but microwave emission from the atmosphere and this must be converted to temperature by a rather involved calculation).

2 comments:

coby said...

nicely presented. You maybe should think about addressing the PDO thing, you know, how ok, Hansen was right, but for the wrong reasons, the warming was natural, not CO2 forcing, then we would have a nice one stop shop for all these strained denials of a rather clear success.

I will add a link to this post in my Hansen Was Wrong Before post.

llewelly said...

Not only that, since scenario A projected the highest CO2 of the 3, and it was the only one showing the 1997-1998 super El-Nino, we have proof that CO2 causes super El-Ninos ...
*removes tongue from cheek*

It's telling to note that Jim Hansen, and essentially all other climate scientists, never do things that way. The real connection between strong El-Ninos and AGW wasn't based on a few bumps in a cherry-picked projection; it was based on real events (the 1982-83 El nino and the 1997-98 El nino), the large rise in atmospheric CO2 levels over the last 30 years, and plenty of sound theory that could be tested in independent ways. Your final paragraph is an amusing way of showing the difference between what how climate scientests actually work, and what some denialists all too often accuse them of doing. However - I have a habit of using this sort of humor in verbal conversations, and it's been my experience that it is often misunderstood. So I laugh, and join in, but I worry, too...