2011-04-15 06:24:18David Evans' Understanding of the Climate Goes Cold
Dana Nuccitelli

Brought this over fron Gen Chat.  Last call for comments.

David Evans' Understanding of the Climate Goes Cold

2011-04-15 07:34:49Comments
John Cook

Struggling to see the difference between flux and quantity of water vapor. Feedback is due to a higher quantity of vapor. Flux leads to higher quantity. Distinguishing between the two seems semantics. Or am I missing the subtleties?

Re hotspot, wonder if it's worth pointing out that despite uncertainty with data, Evans speaks with a distinct lack of uncertainty re a lack of hotspot and what it means. This is one of the great hypocrisies of skeptics - complain about uncertainties of climate science but believe it's not happening with complete certainty.

Under UHI, quote needs to be indented.

Not sure it's wise to quote BEST yet, the results are preliminary and its difficult to predict where a misinformer like Muller will end up with it. There is plenty of evidence without needing to refer to BEST.

2011-04-15 07:51:19Some thoughts
Julian Brimelow


Some comments:


1) "So approximately one-third of the warming is from CO2 alone, and two-thirds from feedbacks, as Evans states."

Evans is suggesting that all the extra warming comes from the moisture feedback alone.  That is not my understanding, there are other feedbacks too.  so him claiming that 2/3 of the warming is soly from the WV feedback alone is exaggerating it.  And his reason for elevating the importance of WV becomes clear later-- dispute that and the feedback issue goes away, well it does not. What about albedo feedbacks etc.?


2) James Annan has also shown +3 K to be the best estimate of climate sensitivity (PDF here).  So maybe worth linking to that too.


3) "First of all, the 'hot spot' is a predicted consequence of any surface warming, based on fundamental atmospheric physics"

Maybe bold "any surface warming" and add, "regardless of the cause of the warming".


4) " The hot spot originates from the adiabatic lapse rate"

I think one should refer to the "moist adiabtic lapse rate" in this case.  is a discussion of Clausius-Claperyon needed here?  That is, maximum moisture content (saturated vapour pressure) being a function of T alone.


5) "The hot spot originates from the adiabatic lapse rate change: the constant flux of evaporating and condensing water vapour which cools the surface by transporting heat away from it"

This is not my field, and I had trouble interpreting this.  Is there perhaps a better concise explanation?  One from a journal paper would be best. 


6) " Weather balloons were not designed to measure long-term climate changes."

Maybe add "especially changes in moisture".  During my research i have read numerous papers on bias issue with the moisture sensors, primarily high up in the troposphere and in the boundary layer.  Also different agencies use different sensors, and sometimes the same agency changes platforms, and new sondes are frequently coming on line-- so lots of issues, especially with moisture.


7)"However, other measurements do indicate the presence of a 'hot spot' in the tropical troposphere."

Such as?  Satellite?  Need to elaborate here, we do not want to throw them any bones.


8) "Further, although the timeframes are too short to be statistically meaningful"

my suggestion in bold.  I think you really need to hammer this home.  Evans is cherry picking, and selecting short-wiondows of time that have no statistical significance. I like the GISTEMP figure that shows the 5-yr running mean, or this one (cleaner).  then again, maybe this one is more convincing:


9) "Tragedy of the Commons"

This is a red herring Dana. Evans misses the point, and is perpetuating a myth that is quite popular right now.  The reason this is a red herring is that we are not talking about trying to reduce global temperatures from current levels!  Tim Lambert summed this up quite nicely:

"Of course this just demonstrates that Abbott has no clue what the whole climate change debate is about. The reason for cutting emissions is not to reduce temperatures from current levels, but to prevent them from increasing to dangerous levels. And the fact that, as Flannery pointed out, CO2 emissions largely stay in the atmosphere for hundreds of years is the reason why we can't just postpone cutting emissions until the temperature rises dangerously -- by then it will be too late."

IMHO, that point really needs to be made-- this meme is gaining traction and really needs to be taken down hard.  


10)  Re the claim that "They keep lowering the temperature increases they expect, from 0.30C per decade in 1990, to 0.20C per decade in 2001, and now 0.15C per decade — yet they have the gall to tell us “it’s worse than expected.”

Is this true?  Who is they?  and who now said 0.15 C?


11)  One of Ari's papers finds that the increase in WVis greater than predicted by models.  Specifically, I think that a direct link to the Wentz et al. (2007) paper should be included too, and perhaps even a quote from the abstract.


12)  Another blunder made by Evans that can be included in the satellite section:  "Why does official science track only the surface thermometer results and not mention the satellite results?"

Nonsense-- you can link to NCDC/NOAA, they include the satellite data from UAH and RSS every damn month; those satellite data are also discussed in the IPCC reports.  Dessler used satellite data, so has Trenberth, on and on.  Really, that statement is simply wrong and ludicrous too-- don't spare any punches Dana, call him on it.


Anyways, excellent job as always.  Thanks for doing this Dana!

2011-04-15 08:10:31
Julian Brimelow

Here is the NCDC/NOAA link. and here.

2011-04-15 08:20:28thanks
Dana Nuccitelli

John - I have a hard time explaining the hot spot.  I got that from Mark, not really sure how to clarify.  Alby:

1) Evans eventually says "two-thirds of their projected warming is due to extra moist air (and other factors)"

2) Annan is referenced in the linked sensitivity page

3) change made

4) change made

5) could use help with this

6) change made

7) link added

8) change made

9) I think Evans is right.  He's comparing to BAU, not present.

10) I skipped this b/c it was so vague.  Not sure it needs a response.

11) Seems like Wentz is saying precipitation is rising faster, not WV

12) Good point, will peck out a section on this

2011-04-15 08:50:52
Julian Brimelow


Re Wentz et al., you are right...sorry about that.


Re 5, John has an explanation here.  Also, from Trenberth and Smith:

"As the climate warms, climate models tend to amplify changes in temperature with height in the Tropics, largely following the moist-adiabatic lapse rate, signaling the dominance of moist convection for determining the lapse rate in the tropical troposphere. For a given increase in surface temperature this means larger increases with height."

From Bengtsson and Hodges (2006):

"At higher surface temperatures, such as being projected in a future climate, the tropical upper troposphere is likely to warm proportionally more than the surface and the lower troposphere. This might be expected because the temperature of the upper troposphere is largely controlled by deep convection. At higher surface temperatures the moist adiabatic lapse rate diminishes leading to a reduced cooling in the upper troposphere. We might thus expect to find a larger warming trend in the upper troposphere than at the surface in a warming climate".

Also from Ramaswamy,

"From the preceding discussions, the lapse rate can be expected to decrease with the resultant increase in humidity, and also to depend on the resultant changes in atmospheric circulation. In general, the lapse rate can be expected to decrease with warming such that temperature changes aloft exceed those at the surface."

ThingsBreak also has an excellent overview.  Note the findings by the uber cool study undertaken by Johnson and Xie (2010) that is included by ThingsBreak.

One small observation, when you link NOAA, you need to remove the "the" before NOAA. 

2011-04-15 09:02:36
Dana Nuccitelli

I think I've linked to a good hot spot explanation.  The difficulty is in explaining how it differs from the WV feedback.

2011-04-16 14:09:21Whoops, I didn’t have time to read this before it was published!
James Wight


Looks good to me, though. I’ve added a link to it from Christy Crock #4.

I presume the 0.3°C/decade, 0.2°C/decade, and 0.15°C/decade come from FAR, TAR, and GISS respectively. Evans conveniently forgets to mention that SAR predicted a slower rate of warming than TAR (see Figure 1.1 of AR4). Also 0.2 is only one significant digit which is compatible with 0.15, and global temperatures are actually in the middle of AR4 projections which are similar to TAR projections.

2011-04-16 14:34:10thanks
Dana Nuccitelli

Thanks James.  We've got CC #4 on the pending schedule.  Should get published in the next few days.  Lots of posts ready to go right now.