2011-01-31 10:57:01Monckton Miscellany - hot spot and evaporation
MarkR
Mark Richardson
m.t.richardson2@gmail...
134.225.187.80

I decided to have a quick pop at this. It needs a better ending and editing as always... not sure about my Earth sweating analogy but I like the inference.

Monckton decided that 6% evaporative cooling leads to the IPCC overestimating temperature rise by a factor of 4. I think he's done his usual trick of just making up his own IPCC projections based on a few nuggets of truth. (I found out how to make a factor of 4, but it's absolute bullshit)

 

 

 

Monckton and the lapse rate

 “In particular, the models predict  that  if and only  if Man  is the cause of warming, the  tropical upper air, six miles above the ground, should warm up to thrice as fast as the surface”

A quick look at the IPCC graphs show that warming from the Sun also causes the tropical upper air to heat up more quickly than the surface:

 

IMAGE

The vertical is atmospheric height and on the horizontal left is North and right is South. In the tropics, models expect the upper atmosphere to warm more than the surface. The Sun has only warmed slightly since 1900 – which is why the graph only shows a little warming but it also shows the tropical upper air warming more quickly than the surface.

As the surface warms more water evaporates and rises into the atmosphere before condensing and releasing latent heat which warms the atmosphere – this is the surface ‘sweating’ and cooling by evaporation. It reduces heating of the surface, and adds to heating of the atmosphere. Anything that warms the surface does this: it is not just ‘if, and only if Man is the cause of warming’.

This ‘tropospheric hot spot’ is the signal of Earth cooling-by-sweating – it’s a 'negative' feedback since it cancels out some of the surface warming. However, atmospheric water vapour should also increase and strengthen the greenhouse effect which is a 'positive feedback', adding to warming.

Scientists have observed this positive feedback (Dessler, 2008) and there are some hints that there is a ‘hot spot’ showing the Earth’s sweating effect is there too, but scientists are not confident about it yet. We have so far failed to detect the cooling feedback but have found the warming one.

Monckton realises that this is a negative feedback because he also says;

"the models predict that every Celsius degree of warming should increase evaporation from the Earth’s surface by 1-3%, but the observed  increase  is more  like 6%. From  this  it  is simple  to calculate  that  the  IPCC has overestimated  fourfold  the amount of warming we can expect from adding greenhouse gases to the atmosphere."

Which suggests that this extra sweating effect is going on. But if it is, then the hotspot must be there because to cool the surface it has to be dumping the heat higher up. Either there is more evaporative cooling and a hot spot, or there isn’t much more evaporative cooling and there isn’t a hotspot. A smaller hotspot higher up means more global warming at the surface.

Monckton implies that a hotspot is a human only response (it isn't) and claims it isn't there (it might be) before saying that in fact we have a much bigger one than models predict - confusing, no?

2011-01-31 11:59:12Image?
John Cook

john@skepticalscience...
123.211.149.21
Which image were you planning to use - the IPCC one showing the patterns from different forcings or the Real Climate pic showing the pattern from greenhouse vs solar warming?
2011-01-31 14:57:49nice
dana1981
Dana Nuccitelli
dana1981@yahoo...
71.140.0.210
Looks good.  I'd just add "axis" after "vertical" and "horizontal".  That last bit could use a little more clarity too.  Do we know where Monckton is getting the 6% figure?  And does it contradict the supposedly missing hot spot?
2011-01-31 20:01:09
MarkR
Mark Richardson
m.t.richardson2@gmail...
134.225.187.80

Going to use the IPCC figures, since anyone can just cross-check the original report to see how I'm right and Monckton's wrong (or at least, misleading. Perhaps GHG is 3 times faster than surface but solar is only 2.7 times). Will add axis, I'm going to just cut out the solar and greenhouse gases.

 

 

The 6% figure comes from Clausius-Clapeyron iirc and there is a paper somewhere using satellite microwave measurements to estimate it. I planned to find it again later, but I spoke to a feedbacks guy and he's not too confident that it's a good way of measuring it. If there was that much evaporation though it would have to condense higher up and be more warming!

2011-02-01 09:52:17Some information
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Hi MarkR,

Thanks for tackling this.  I suspect you know more about this than I do, but FWIW, here are some of my thoughts (derived from the literature).

Trenberth et al. (2005) wrote a paper about trends in precipitable water vapour content over the oceans:

"Combining the two errors, gives an overall trend as 0.40±0.09 mm/decade, where these are 95% confidence limits. In terms of percent, which places more emphasis on higher latitude trends, the trend is 1.28±0.29%/decade, which we round to 1.3±0.3%/decade. 

Much of the pattern of trends can be explained by the observed SST trends over the same period. Wentz and Schabel (2000) find, for a much shorter period, that the regression coefficient is 9.2% K-1. We find the best value for the time series from 30°N–30°S is 7.83 ±0.1% K-1 (correlation 0.87) for 1988–2003 or 8.87 % K-1 for the global ocean (correlation 0.84), see Fig. 12. Both correlations are highly statistically significant. The spatial correlation between the fields in Figs. 11 and 12 for 1988–2003 is 0.60 for 30°N to 30°S and 0.65 over the global oceans, both statistically significant at the 5% and 1% levels. The regression values are very close to the 7% K-1 expected from Clausius-Clapeyron equation for the water-holding capacity of the atmosphere, but are presumably slightly larger owing to the amplification associated with air temperature versus SST (especially with altitude in the tropics associated with the moist adiabatic lapse rate)."

More in the IPCC here and here.

I have no idea where Monckton gets his claim that "the models predict that every Celsius degree of warming should increase evaporation from the Earth’s surface by 1-3%, but the observed  increase  is more  like 6%".

IIRC, the change in evaporation form the ocean's surface and evapotranspiration (evaporation plus transpiration)  from the land surface will differ.   From the IPCC:

 "Dai (2006) analysed near-global (60°S–75°N) synoptic data for 1976 to 2005 from ships and buoys and more than 15,000 land stations for specific humidity, temperature and relative humidity. Nighttime relative humidity was found to be greater than daytime by 2 to 15% over most land areas, as temperatures undergo a diurnal cycle, while moisture does not change much. The global trends of near-surface relative humidity are very small. Trends in specific humidity tend to follow surface temperature trends with a global average increase of 0.06 g kg–1 per decade (1976–2004). The rise in specific humidity corresponds to about 4.9% per 1°C warming over the globe. Over the ocean, the observed surface specific humidity increases at 5.7% per 1°C warming, which is consistent with a constant relative humidity. Over land, the rate of increase is slightly smaller (4.3% per 1°C), suggesting a modest reduction in relative humidity as temperatures increase, as expected in water-limited regions."

I think Monckton may have gotten his 1-3% range from Held and Soden (2006), except they are talking about precipitation and not evaporation!  In their Figure 2a (A1B scenario and in the 20C3M simulations), they show the models projected increases in mixing ratio with temperature lies along the 7.5%/K line, it is the modelled precip. which has a slope of 2.2%/K

MarkR, I can email you a recent paper by Liepert and Previdi  (Do Models and Observations Disagree on the Rainfall Response to Global Warming?) that might be very useful, as well as the Held and Soden paper.  From the paper:

 "Climate models (e.g., Allen and Ingram 2002) confirm an increase in the total amount of water vapor in the
atmosphere at approximately the CC [Clausius-Clapeyron] rate."

 Allen, M. R., and W. J. Ingram, 2002: Constraints on future changes in climate and the hydrologic cycle. Nature, 419, 224–232.

Caveat:  I had a quick read of the Allen and Ingram paper, but nowhere did I find evidence ot support the claim cited in Liepert and Previdi. 

PS:  If the AOGCMs are underestimating the increase in ET and E, then this suggests that they might be actually underestimating the WV feedback, and in turn could be underestimating the climate sensitivity. So I am not sure how this is meant to support Monckton's climas about alleged "alarmist" predictions or claims that the models are overestimating climate sensitivity.  Again, I suggest whoever is writing this solicits feedback from a climate scientist such as Solomon, Schmidt or Trenberth.

 

 

2011-02-01 23:37:13
MarkR
Mark Richardson
m.t.richardson2@gmail...
192.171.166.144

Thanks for the extra links Albatross, I'll make sure to go through them and check I didn't put anything wrong before posting this. No need to email, I can read them!

 

"PS:  If the AOGCMs are underestimating the increase in ET and E, then this suggests that they might be actually underestimating the WV feedback, and in turn could be underestimating the climate sensitivity."

"except they are talking about precipitation and not evaporation!"

 

Precip has to be very close to evaporation - atmospheric residence time is something like 9 days so each day evaporation equals about 10% of the amount of water vapour in the atmosphere. If you had evap increase at 6% and precip at 3% after 1 K of warming, then you would be increasing atmospheric water vapour at 0.3% of its original value per day, so in a year you would double it.

Similarly, much higher evaporation doesn't necessarily mean much higher water vapour content since evap ~ precip. We think there's a positive relationship but you could easily have a 6% increase in precip and a 6% increase in evap and no net change (although we do expect a small period where evap outweighs precip before 'equilibrium', so the amount would increase according to Clausius-Clapeyron).

 

Independent measures of water vapour content and of evaporation/precip should inform us. IMO there is almost certainly a hot spot if the evap data are right, we're just struggling to detect it because of the smeared out weighting functions for satellite measurements and problems with weather balloons at that height.

 

I ran through this with a different Allen

2011-02-02 03:01:12
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Hi MarkR,

"No need to email, I can read them!"

Sorry did not mean to offend, I do not know what your training and field of expertise is, so I was applying the precautionary principle :)

Thanks for clarifying further. Did you get that 9 days residence time from one of Trenberth's papers?  I had a reference for that then lost it in my PDF library.

I agree with what you say, the only concern I have is this:

"Precip has to be very close to evaporation"

IIRC, this is probably true over the oceans, but it is not necessarily so over land because of infiltration, water storage terms, and runoff.  Specifically,

P = ET+ R and delS,

where P is precip., ET is evapotranspiration, R is the net surface runoff, and delS the net change of soil moisture (equivalent to the change of water storage in the soil column). Here the role of groundwater storage has been ignored (i.e., aquifers), as has horizontal moisture transport.

People just like Monckton do not understand how difficult it is to close the surface energy budget at a field site and to accurately measure ET, even when using a top quality eddy-covariance system, never mind trying to remotely sense the "hot spot".....

Looking forward to reading your article Mark.

 

2011-02-02 05:20:33
MarkR
Mark Richardson
m.t.richardson2@gmail...
134.225.187.80

Sorry did not mean to offend,

It didn't even cross my mind that I could take offense to that. Should have let me know I was allowed to! :P


 

Hmm, I was talking about the global precipitation vs evaporation rates. They have to be very very close (averaging to constant in time if temperature is constant) or atmospheric water vapour would soar off to impossible values! Regionally ofc I agree they can be very different - there might be a net transfer from the oceans to groundwater but that's not relevant in terms of forcing/feedbacks afaik?

2011-02-02 05:33:56
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

MarkR if one is looking at truly global rainfall then, yes, P ~ E; but I am not aware of any truly global observational studies.  Then again, if we are using models then I see your point, b/c those are global. So I see your point.

I still find it odd that Monckton seems to have mixed up P and E though.

Groundwater can play a role in land-atmosphere feedbacks, for example.  But for the purpose of your article this is not really a concern-- at least IMHO.

 

2011-02-02 05:45:50
Rob Painting
Rob
paintingskeri@vodafone.co...
118.93.193.188
As far as the hotspot, there's this recent paper too: http://www.sciencedaily.com/releases/2010/11/101108102612.htm
2011-02-02 05:58:41
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Good find Rob!

 

 

2011-02-04 20:27:19
MarkR
Mark Richardson
m.t.richardson2@gmail...
134.225.187.80

Hmm, the first Trenberth paper seems to be reporting on precipitable water (amount in the atmosphere, positive feedback) rather than rates of evaporation (lapse rate cooling, negative feedback).

 

But I don't think the point is currently that important to fully check. Monckton has made a huge contradiction here and that's the narrative I'm going to run with. Researching each of his mistakes and all the corollaries in full would take a lifetime and he is much more efficient at getting stuff wrong than analysis is at correcting each of those mistakes. :(

2011-02-04 21:34:25
MarkR
Mark Richardson
m.t.richardson2@gmail...
134.225.187.80

It's now here, I still need to add in the references and change a little bit. I've emailed SPPI to see if Monckton will confirm that he's made the enormous mistake that I think he has.

The SPPI guy has forwarded my email and says CM is good at responding quickly. Hopefully I didn't make a stupid mistake :P

2011-02-05 03:39:56second figure
dana1981
Dana Nuccitelli
dana1981@yahoo...
38.223.231.252

I like the conclusion better now - it's much clearer.

But in the second figure, isn't light yellow slower warming than dark yellow/orange?  It seems like it's a (relatively) cold spot, not a hot spot.

2011-02-05 04:03:47
MarkR
Mark Richardson
m.t.richardson2@gmail...
192.171.166.144

Hmm, weird. The colours from Monckton's presentation (where I took this) seem to have moved around. In the original version the solar 'hot spot' is yellow and the surrounding area yellow-y green. There is a hot spot... I'll change the pic.

2011-02-18 09:14:50status?
dana1981
Dana Nuccitelli
dana1981@yahoo...
38.223.231.252
You still working on this Mark?  Looks like Monckton's figure is still in there.
2011-02-19 04:26:42
MarkR
Mark Richardson
m.t.richardson2@gmail...
192.171.166.144

I need to add some references to the theory side, largely leaving the writing as is.

 

Monckton's response was unsatisfactory, he dodged conservation of energy etc. I'm about 90% sure he's got it completely wrong, but he's trying to avoid admitting his contradiction or he doesn't understand. I've checked with Richard Allen & Andrew Dessler who bother confirmed my understanding, so I'll post this once I've added the references.

 

 

But I also have a project meeting for my research on Tuesday and I have to present some stuff then, so I'm v busy! :P

2011-02-19 04:27:33
MarkR
Mark Richardson
m.t.richardson2@gmail...
192.171.166.144
I got a good reply from him though... in his response to Steketee he says 'if and only if man is the cause'. In his email to me he accepted that it's from natural causes too. He's not completely in denial of evidence...
2011-02-24 05:02:29
MarkR
Mark Richardson
m.t.richardson2@gmail...
192.171.166.144
I updated it a bit more. Almost happy to publish it, getting my friend to look through and tell me what he's confused by so I can try to be clearer!
2011-02-25 03:42:56hang on there cowboy
dana1981
Dana Nuccitelli
dana1981@yahoo...
38.223.231.252
Did you intend to publish this, Mark?  Please hang on, I just published my response to Motl, and we've got a few others in the pipeline as well.
2011-02-25 04:52:12
MarkR
Mark Richardson
m.t.richardson2@gmail...
134.225.187.80

I published it already :/

 

Mistake I made was I originally embargoed it for the 8th April or something like that. When I tried to publish it got messy. I think there's a bug in there :/

2011-02-25 05:29:43
dana1981
Dana Nuccitelli
dana1981@yahoo...
38.223.231.252

Yeah I tried to stop you, switching it back to unpublished twice.  But you didn't take the hint! :-)

No biggie, now that the email went out we can't do much about it at this point.  It's okay, we generally prefer giving each post its time alone in the Sun, but at least yours was on the same topic (hot spot) as Motl and things break.  So if we were going to do 3 in quick succession, those are good choices.