2011-04-19 15:31:42Lindzen Illusion #1: We Should Have Seen More Warming
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.97.203

I drafted up LI #1, which is mostly a re-post of the 'Case Study of a Climate Scientist Skeptic."  Except in the calculation this time, instead of trying to estimate the heat going into the oceans, I just used transient climate sensitivity, which I think is a better approach.  I'd also appreciate feedback on whether the tone of the intro is okay.

Lindzen Illusion #1: We Should Have Seen More Warming

2011-04-19 16:27:54"lit a fire under the buns"
John Cook

john@skepticalscience...
60.231.60.165

Is that an expression? Very vivid imagery. But lest everyone be thinking about Jo Nova's buns, maybe you should just go with "lit a fire under the purportedly non-political global warming "skeptic" movement :-)

2011-04-19 18:16:06
nealjking

nealjking@gmail...
84.151.40.157

Well, they'll have to think about CM's buns as well - that should put them right off!

2011-04-20 01:24:56hah
dana1981
Dana Nuccitelli
dana1981@yahoo...
64.129.227.4

Well the expression is "lit a fire under his ass", but I didn't want to use that language :-)  But I can certainly take the buns out too.

2011-04-20 08:26:20
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Dana,

Not sure if you know, but Hansen has a new paper in the works in which he claims that the negative forcing from aerosols is -1.6 W m-2 +/- 0.3. Not sure whether or not this is helpful.  That sounds like a really high value to me, on par with CO2 forcing alone no?

I am a great lover of buns, but best to leave it out ;)  Not sure about making reference to 'doped up', maybe something more sophisticated is in order.

2011-04-20 09:24:15Hansen
dana1981
Dana Nuccitelli
dana1981@yahoo...
64.129.227.4

Thanks Alby.  I saw that paper but didn't get a chance to read it.  -1.6 W/m2 is definitely on the high side (about 0.4 W/m2 larger than the IPCC most likely value and almost as large as CO2, though that's now nearly 1.8 W/m2).  Certainly plausible though.  Maybe I'll run the numbers for that forcing as an alternative possibility.  Maybe use 1.8 W/m2 for CO2 and -1.6 W/m2 for aerosols.

I'll modify the language you mention a bit too :-)

2011-04-20 13:35:36right on
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.97.203

Funny, using those values, the "expected" warming comes out to 0.8°C.  Suck on that, Lindzen!

2011-04-21 16:33:46
Rob Painting
Rob
paintingskeri@vodafone.co...
118.92.111.75

Looks good to me.

2011-04-21 18:19:10I got a different value
James Wight

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112.213.169.211

Dana, you might find a basic error in my calculations again!

 

Equilibrium temperature change ΔT = λ*ΔF

λ = 0.8 K W-1 m2

ΔF = GHGs – aerosols = 2.7 – 1.6 = 1.1 W m-2

ΔT = 0.8*1.1 = 0.9 K

 

Transient temperature change ΔT = λ*ΔF

λ = 0.8 K W-1 m2

ΔF = GHGs – aerosols – energy imbalance = 2.7 – 1.6 – 0.6 = 0.5 W m-2

ΔT = 0.8*0.5 = 0.4 K

 

Turning the equation around to derive climate sensitivity:

λ = ΔT/ΔF

ΔT = 0.7 K

ΔF = 0.5 W m-2

λ = 0.7/0.5 = 1.4 K W-1 m2 = 5.1 K per doubling of CO2

2011-04-22 01:19:10
dana1981
Dana Nuccitelli
dana1981@yahoo...
64.129.227.4

A couple things James.  In the first set of calculations, I'd suggest using more up-to-date GHG forcings, which brings it up to about 2.8 W/m2 and the net to 1.2 W/m2.  There's also the solar forcing if you want to be thorough, bringing it up above 1.3 W/m2, and ΔT to close to 1.1°C.

In the second set again I'd up the ΔF by about 0.2 to 0.25, so the ΔT becomes about 0.6 K.  That's a bit low, so it would suggest either the aerosol forcing or energy imbalance (or both) are slightly high.

In the third set ΔT = 0.8 K and ΔF = 0.73 W/m2, so λ = 1.1 = 4.1 K for 2xCO2.

2011-04-22 15:04:46
James Wight

jameswight@southernphone.com...
112.213.135.49

You’re right, the GHG forcing should be 2.8 W m-2 – I mistakenly rounded down instead of up. If anything I would think the energy imbalance is slightly low, because it’s being measured in a solar minimum and we don’t have good measurements of the deep oceans.

If I correct the GHG forcing and add in the solar forcing, I get 0.6°C. But I still don’t get the 0.8°C you use in your article. And a 4°C sensitivity seems like it’s worth mentioning.

2011-04-22 15:20:25
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.97.203
Well I had a slightly different approach, using transient sensitivity instead of the imbalance, which is hard to measure.
2011-04-22 15:42:06Forcing
James Wight

jameswight@southernphone.com...
112.213.135.49

But you also used a forcing of 1.5 W m-2. Where did the extra 0.2 W m-2 come from?

2011-04-22 16:05:19
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.97.203
Increasing aerosols to -1.6 W/m2 decreased it by 0.4, and increasing CO2 to 1.8 W/m2 increased it by 0.15 (in comparison to the IPCC numbers).
2011-04-22 16:46:07
James Wight

jameswight@southernphone.com...
112.213.135.49

That’s still only 1.35. These equations are fascinating; ±0.1 here and there and you get quite different results.

Rearranging the equations to derive the energy imbalance…

Energy imbalance = ΔFe – ΔFt = ΔTee – ΔTte = 1.0/0.8 – 0.8/0.8 = 0.25 W m-2

(sub e = equilibrium, sub t = transient)

…I get only 0.25 W m-2, much smaller than observed.

2011-04-23 02:34:49forcing
dana1981
Dana Nuccitelli
dana1981@yahoo...
64.129.227.4

Oh, I think the discrepancy is that I'm using the net IPCC forcing (1.6 W/m2 anthro plus 0.12 solar) whereas you're just using GHGs and aerosols, right?

2011-04-23 13:37:51Okay, it's making more sense now
James Wight

jameswight@southernphone.com...
112.213.160.149

Equilibrium temperature change: ΔTe = λe*ΔFe

λe = 0.8 K W-1 m2

ΔFe = 1.5 W m-2

ΔTe = 0.8*1.5 = 1.2 K

 

Transient temperature change using energy imbalance: ΔTt = λe*ΔFt

λe = 0.8 K W-1 m2

ΔFt = 1.5 – 0.6 = 0.9 W m-2

ΔTt = 0.8*0.9 = 0.7 K

 

Transient temperature change using transient climate sensitivity: ΔTt = λt*ΔFe

λt = 0.5 K W-1 m2

ΔFe = 1.5 W m-2

ΔTt = 0.5*1.3 = 0.7 K

 

Climate sensitivity using energy imbalance: λe = ΔTt/ΔFt

ΔTt = 0.8 K

ΔFt = 0.9 W m-2

λe = 0.8/0.9 = 0.9 K W-1 m2 = 3.3 K for 2xCO2

 

Climate sensitivity using temperature change: λe = 1.5λt = 1.5ΔTt/ΔFe

ΔTt = 0.8 K

ΔFe = 1.5 W m-2

λt = 0.8/1.5 = 0.5 K W-1 m2 = 2.0 K for 2xCO2

λe = 1.5λt = 3.0 K for 2xCO2

2011-04-23 14:12:46yep
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.97.203

Yep, that looks about right.