From NCAR:
Future warming likely to be on high side of climate projections, analysis finds
November 08, 2012
BOULDER—Climate model projections showing a greater rise in global temperature are likely to prove more accurate than those showing a lesser rise, according to a new analysis by scientists at the National Center for Atmospheric Research (NCAR). The findings, published in this week’s issue of Science, could provide a breakthrough in the longstanding quest to narrow the range of global warming expected in coming decades and beyond.
NCAR scientists John Fasullo and Kevin Trenberth, who co-authored the study, reached their conclusions by analyzing how well sophisticated climate models reproduce observed relative humidity in the tropics and subtropics.
The climate models that most accurately captured these complex moisture processes and associated clouds, which have a major influence on global climate, were also the ones that showed the greatest amounts of warming as society emits more greenhouse gas into the atmosphere.
“There is a striking relationship between how well climate models simulate relative humidity in key areas and how much warming they show in response to increasing carbon dioxide,” Fasullo says. “Given how fundamental these processes are to clouds and the overall global climate, our findings indicate that warming is likely to be on the high side of current projections.”
The research was funded by NASA.
Moisture, clouds, and heat
The world’s major global climate models, numbering more than two dozen, are all based on long-established physical laws known to guide the atmosphere. However, because these relationships are challenging to translate into software, each model differs slightly in its portrayal of global climate. In particular, some processes, such as those associated with clouds, are too small to be represented properly.
The most common benchmark for comparing model projections is equilibrium climate sensitivity (ECS), or the amount of warming that eventually occurs in a model when carbon dioxide is doubled over preindustrial values. At current rates of global emission, that doubling will occur well before 2100.
For more than 30 years, ECS in the leading models has averaged around 5 degrees Fahrenheit (3 degrees Celsius). This provides the best estimate of global temperature increase expected by the late 21st century compared to late 19th century values, assuming that society continues to emit significant amounts of carbon dioxide. However, the ECS within individual models is as low as 3 degrees F and as high as 8 degrees F (, leaving a wide range of uncertainty that has proven difficult to narrow over the past three decades.
The difference is important to reconcile, as a higher temperature rise would produce greater impacts on society in terms of sea level rise, heat waves, droughts, and other threats.
Clouds are one of the main sticking points, say the NCAR authors. Although satellites observe many types of clouds, satellite failure, observing errors, and other inconsistencies make it challenging to build a comprehensive global cloud census that is consistent over many years.
However, satellites perform better in measuring water vapor, and estimates of the global distribution of relative humidity have become more reliable. Relative humidity is also incorporated in climate models to generate and dissipate clouds.
Fasullo and Trenberth checked the distribution of relative humidity in 16 leading climate models to see how accurately they portray the present climate. In particular, they focused on the subtropics, where sinking air from the tropics produce very dry zones where most of the world’s major deserts are located. The researchers drew on observations from two NASA satellite instruments — the Atmospheric Infrared Sounder (AIRS) and Clouds and Earth’s Radiant Energy System (CERES) – and used a NASA data analysis, the Modern-Era Retrospective Analysis for Research and Applications (MERRA).
The seasonal drying in the subtropics and the associated decrease in clouds, especially during May through August, serve as a good analog for patterns projected by climate models.
“The dry subtropics are a critical element in our future climate,” Fasullo says. “If we can better represent these regions in models, we can improve our predictions and provide society with a better sense of the impacts to expect in a warming world.”
Accurate humidity yields higher future temperatures
Estimates based on observations show that the relative humidity in the dry zones averages between about 15 and 25 percent, whereas many of the models depicted humidities of 30 percent or higher for the same period. The models that better capture the actual dryness were among those with the highest ECS, projecting a global temperature rise for doubled carbon dioxide of more than 7 degrees F. The three models with the lowest ECS were also the least accurate in depicting relative humidity in these zones.
“Because we have more reliable observations for humidity than for clouds, we can use the humidity patterns that change seasonally to evaluate climate models,” says Trenberth. “When examining the impact of future increases in heat-trapping gases, we find that the simulations with the best fidelity come from models that produce more warming.”
The authors focused on climate models used for the 2007–08 assessment by the Intergovernmental Panel on Climate Change. The next-generation models being used for the upcoming 2013–14 IPCC assessment were found to behave in a similar fashion, as described in a preliminary analysis by the authors in a supplement to their paper.
“In addition to providing a path forward and focus for improving models, results strongly suggest that the more sensitive models perform better, and indeed the less sensitive models are not adequate in replicating vital aspects of today’s climate,” write the authors in the paper.
About the article
Title: A Less Cloudy Future: The Role of Subtropical Subsidence in Climate Sensitivity
Authors: John Fasullo and Kevin Trenberth
Journal: Science
The humidity anomalies in that region are very closely related to ENSO,
And ENSO prediction (by computer models) is about as good as a headless chicken, as demonstrated this year…there was blood everywhere. Hey Trenberth, lookout the window, its raining chickens.
South Park – American Economics
The money these charlatans get would be better spent putting them in prison.
LetsBeReasonable says:
November 8, 2012 at 11:30 pm
“Michealwiseguy,
I thought this idea had been refuted as the the last three solar cycles spanning the last 33 years or so had not effected earth’s climate as it seemed to go up steadily over that time.”
Every time I hear the words “Climate Change”, I think to myself, “Man-Made Climate Change” Or “Natural Climate Change”.
What the heck are they talking about?
You can’t heat water from above.
So they can’t measure clouds so they measure humidity.
They can’t use real data so they use models.
They then assume it will cause more warming.
The Guardian then assumes higher temperatues will cause more extreme weather.
http://www.guardian.co.uk/environment/2012/nov/08/climate-change-severe-models
Blimey, where did the facts and the truth disappear to?
From the paper:
“Constraining simulated clouds is
a challenge, however, as clouds are complex and
difficult to observe. The historical record is plagued
by errors associated with the drift and failure of
satellites, inconsistencies in the detection of clouds,
and instrument biases (8). Moreover, clouds can
vary not just in their bulk characteristics but also
in their microphysical properties, for which global
observations are lacking generally, and considerable
uncertainty persists regarding the feedbacks
of various cloud types that may occur in a
changing climate (9). Hence, owing to the wide
range of scales involved, cloud processes in models
are often not represented explicitly but instead
are parameterized and tuned. Although there is
some anticipation that new satellite programs may
begin to address observational issues, and model
resolution is improving, it is likely to be several
decades before observations provide an adequate
constraint on models.”
Nonetheless, F&T use what appears to be just five years (2002-2007) of Aqua data plus two decades of balloon RH measurements to detect a relationship between RH and equilibrium climate sensitivity (positive in the moist ascending air in the tropics and negative in the dry descending air in the subtropics). Using the measured RH vs model predictions only 3 models were within the uncertainty range in the dry subtropics: J, N, and P. H, K, and M were almost inside the range as well. Model names are:
A: NCAR PCM-1
B: INMCM 3.0
C: IAP FOALS 1-0g
D: NCAR CCSM3.0
E: GFDL CM2.0
F: CSIRO MK3.0
G: MRI CGCM 2.3.2a
H: UKMO HADCM 3
I: GFDL CM2.1
J: CCCMA CGCM3.1 – T47
K: CCCMA CGCM3.1 – T63
L: MPI ECHAM5
M: MIROC 3.2 Medres
N: MIROC 3.2 Highres
O: IPSL CM4
P: UKMO HADGEM 1
It is interesting that the graph shown in the press release does not appear in the F&T article, nor in their Supplemental Information, nor does it appear in the Perspectives article by Karen Shell.
This is really good news, if it’s correct.
It would be rather smashing if we could escape the ice age period we have been in the last 2 million years?
If CO2 is the way to stop the ice ages I have problems with UNFCCC that wants to undermine the use of CO2 as a ice age killer?
How many will die in the comming ice age?
Correction: I now see that the graph in the press release is just a reversed version of part of Figure 4 in the main article, with the alphabetical identification of the models removed and replaced by stars.
Trenberth should have been fired from NCAR long ago. Climategate proved what a freakin’ liar and corrupt “scientist” he was with the whole Chris Landsea affair. His credibility ship sailed and sank long ago.
Let me see if I’ve got this…..
There’s this amazing new study, published in a prestigious journal, which shows that temperature rises are more likely to be in the 3 – 5 Celsius range per doubling, than the 2- 3 Celsius range.
Ahh, so THAT’S the reason we’ve had LESS than the LOWER range of projections for the last 15 years or so.
All that high end warming must be hiding just around the corner, ready to spring out and surprise us very, err, soon, honest, just you wait and see, unless we all sacrifice to Gaia immediately.
I mean, it would be a TRAVESTY if these guys were just making sh*t up to try and flog a bit more life out of their dead hobby horse.
Yet based on current observations of the performance of the projections and today’s global mean temps means we can also say:
http://www.appinsys.com/globalwarming/GW_TemperatureProjections.htm
They are cheery picking climate models.
a) Get the climate models that show the maximum temp rise.
b) Search through all the different parameters and variables they tweak.
c) Find a variable or variables that fits your story.
d) They call this is science.
Then there is the little matter of the missing hotspot. JoNova takes on John Cook.
http://joannenova.com.au/2010/06/how-john-cook-unskeptically-believes-in-a-hotspot-that-thermometers-cant-find/
“Yet another paper shows the hot-spot is missing.”
http://joannenova.com.au/2011/10/this-is-90-certainty-really-yet-another-paper-shows-the-hot-spot-is-missing/
Every new paper in the arena of climate just goes to prove that the science was not settled when they told us it was. Don’t they realise the illogicality of their (ever changing) positions? No-one has to answer that – it is obvious that they never have.
This exercise is a variation on the “hot spot” that is supposed to appear in that same exact portion of the atmosphere and which has famously not done so.
It will be very interesting to see if one of the coverups for the missing hot spot is some reference to this paper.
Don’t underestimate how important this hot spot is to the GCM’s. It is the major expected effect of “back radiation” and all the models expect it to appear. It is not there and many, many measurements confirm this. The humidity search is a proxy for the hot spot search. It simply has to be there for the back-radiation hypothesis to work.
The switcheroo will come later when humidity will be transmuted into climate gold with the flick of a pen by pointing out that the latest models (only) are able to get the water vapour right. This will in turn provide a model of the hot spot’s eventual appearance. The First Coming will be a truly religious experience.
So, expect a follow-up paper confirming the finding that the newest and most expensive models are doing a better job of tracking down that pesky hot spot, so essential to the CO2 warming theory. It is interesting that the warmists are so much more predictable than the climate.
Keep your eye on this topic. AR5 has to address it. How the fudge and kludge is worded matters. They don’t want it picked apart too easily too soon. Expect misdirection, obfuscation and homogenisation to rule the day. If they can’t find it all the models are wrong at the core.
“Lie Hard II” Starring Kevin Trenberth. Why limit yourself to mildly warmer weather plausibly extrapolated from today’s weather when you can really jump the shark with models that diverge completely from reality? Because the bigger the lies you tell, Kevin, the more likely it is that people will wake up to the truth. So go ahead Kevin. I suggest next week you tell the masses that the earth will get so hot that even granite will melt and we’ll all sink into the furnace. See where that gets you.
I would have asked the computer how closely they track temperature if that’s the variable you want them to forecast. But what would I know, I’m not a climatologist.
This is quite brilliant.
Now they are seeking statistically significant correlations between the outputs of the climate models.
And writing articles about the result as if it actually means something.
The people who run models need to answer one simple question, why is it that the actual estimated temperatures for the globe are tracking closer to IPCC Scenario C than any other.
I regard Scenario C is the perfect ‘null hypothesis’ as it can be recast as ‘any extra CO since 2000 does not have the effects we predict in our models’ or ‘we do not correctly understand the outcome of extra CO2 oi our models’. This is because Scenario C was the one thing that did not happen in the real world.
Wherever the actual estimated temperatures for the globe are, they should never be close to Scenario C unless some very good, solid explanation can be given as to why.
Talk given by Dr Jasper Kirkby, head of the CLOUD experiment at CERN, on 7 November 2012. Cosmic rays, climate and the CERN CLOUD experiment:
http://cdsweb.cern.ch/record/1492173
The name Trenberth is a mark of quality … but not good quality.
You cut down forests and turn it to farmland, there are less plants, evaporation decreases, there is less loss of heat through evaporation and temperatures go up.
What more need be said? It just confirms the sceptic position that other things than CO2 cause climate change.
The “acid test” for a climate model must be how well the measured TEMPERATURE replicates the modeled TEMPERATURE (for multiple latitudes, months, years, altitudes, …).
If someone publishes a paper comparing humidity predictions of multiple [unvalidated] climate models with southern subtropical wintertime atmospheric humidity measurements at a specific altitude range (without also summarizing data from other latitudes, months, years, altitudes, … let alone temperatures!), it looks like they’re picking cherries from an extended ladder. (Could be a Josh cartoon idea).
Besides, one would need to present data showing conclusively that the INCREASE of CO2 concentration caused an INCREASE in RH (and Temp) at specific altitudes in order for the claim of positive feedback multipliers to be true. (Or so goes the “theory”).
But the claim that this somehow raises the probability of climate models assuming a high ECS being “correct” is risible. Such is the state of peer reviewed literature.
This raises more questions than answers. For example, wasn’t Trenberth supposed to be looking for MISSING HEAT some 20,000 leagues under the sea?
Kurt in Switzerland
Appalling logic by scientists, one of whom pretends to be a world leader on climate change. His main problem is that his number 1 assumption is that his pre-conceived conslusion can’t be wrong. His whole effort seems to be aimed at proving his belief. And I don’t care what his beliefs are. When it dawns on him (some time soon) that he is going about all this the wrong way I think he is going to experience a rather uncomfortable let down. Missing heat, missing information,……missing the point seems more like it.
“Because we have more reliable observations for humidity than for clouds, we can use the humidity patterns that change seasonally to evaluate climate models,” says Trenberth. “When examining the impact of future increases in heat-trapping gases, we find that the simulations with the best fidelity come from models that produce more warming.”
Which is evidence of precisely nothing.
Otherwise, it looks like they found an aerosol effect (the subtropical monsoonal zone is particularly sensitive to aerosol changes) and interpreted as a GHG effect.
Lets stipulate that the models are correct then sensitivity is about 4 (give or take). Should Trenbeth not give up his quest for missing heat and now be looking for missing Temp, given the amount of CO2 increase in the last century?