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
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“Sophisticated” climate models? How robust. Tweaky-tweaky, climate-speaky.
“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,”
Bwahahaha!
Robin Williams was the guest comic tonight on The Late Show With David Letterman.
Maybe Letterman could get Kevin to fill Robin’s place, next week.
Well, we can’t model clouds properly, we have no idea what the right value is for aerosols, we’ve got no explanation for why the warming the models have predicted so far is no where to be seen, we can’t figure out where the missing heat is, but we figured out that some of the models get humidity right in some of the places on earth for some period of time from which we conclude that it is worse than we thought.
Priceless.
Decide what result you want. Run your model to give that result. Find one spot on the planet where your model matches reality a little bit for just one factor. Say that that one spot and that one factor are more important than anywhere else on the planet and more important than any other factor.
The fact that your model gives appallingly bad results everywhere else on the planet and for every other factor is conveniently ignored.
Like I said before, they aren’t telling bigger lies out of desperation, they are telling bigger lies because they are getting away with it, and the MSM and the “scientific” journals are helping them.
I want these charlatans taken down, and fast. But how???
We admit there is climate change due to natural causes, especially solar cycles.
The current Grand Solar Minimum should be pointed out as the major cause for the cooling planet, brutal winters, and crop failures.
Oh, it”s Travesty Trenberth again. A waste of time reading, then.
For years we’ve been told that the main amplifying mechanism for CO2-induced warming has been increased water vapor. Now we’re told that the models that have the smallest increases in water vapor show the most warming…
This shows that models assumed a high correlation between sub-tropical RH and temperature, in the southern winter in 2008. What else does it prove?
It also shows that the vast majority of models missed the boat altogether. The output of 13 of them (81%) simply didn’t match the actual observed outcomes. The majority didn’t even come close.
The authors say leading models have consistently shown ECS of 3°C for over 30 years. And then they cherry-pick 11 models (out of 16) that show ECS higher than 3°C.
“The research was funded by NASA.”
The institutional hero of my childhood is becoming a pain. Haven’t they got more productive things to do, like, oh, I don’t know, explore space?
Please name the models that you admit are now proven to be inadequate.
It’s not clear to me at all why they would say that because a certain model predicts humidity today well it will predict temperature tomorrow well. These people should spend less time on playing with what they seem to think are “godlike” models that because they tune them to fit one parameter well necessarily predict other parameters well and instead focus on real world problems with their theories.
1) what’s happened to the energy of the last 16 years generated by the half of all the co2 ever poured into the atmosphere by man? It appears to be gone. Please spend more energy finding the missing energy because your 100 year predictions are kind of moot when you can’t satisfy the law of conservation of energy. Nobody is going to believe any prediction from a model that doesn’t conserve energy.
2) How is it even remotely possible for temperatures to rise 7 degrees by 2100 considering we are on a 0.6C course for 2100 at a linear increase using the last 50 years or so as a base. When does the discontinuous sudden acceleration occur and why?
Perfect. Just what the funding prescribed and what the bureaucrats want to hear. Yet the vaunted models failed to predict the last 15 years of statistically insignificant change, in the face of rising CO2. But of course we don’t talk about that any longer do we. Now it’s simply climate change (whatever the hell that means) and anthropogenic influence (any and everything).
Where is Scotty and his Transporter when one really needs him?
The article is behind a paywall. Which models were the good ones?
If science were settled, it would not be necessary to have several climate models. One should be enough.
If there are several climate models, obviously all of them, except maybe one, are wrong.
If there are several climate models, that does not necessarily mean that one of them is right.
Something is really, really wrong in this branch of science when you have to state the obvious.
Unfortunately, governments will keep supporting these buffoons doing futile math exercises (I bet they are pretty good by now in any math test) since it gives them an excuse to raise more money through taxes or support their buddies, making them rich, by offering grants and subsidies.
It would take somebody with lots of political weight and brass spherical anatomical parts, to make a true stand and gather a team to debunk all this (scientifically simple, politically complex challenge).
I am sure that, in countries where the carbon tax is being effected, a smart politician could make a killing and become a hero is he/she eliminates it.
“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.”
And if we just happen to look at those high warming models and compare them to actual empirical observations do any of them remain unfalsified at the 95% certainty interval? Or even the 99% interval?
Or would it be inconvenient to note that?
“…reached their conclusions by analyzing how well sophisticated climate models reproduce observed relative humidity in the tropics and subtropics.
…”
Said the Travesty Kid!
‘Climate science’ Commandments 3 and 4:
“Thou shallt make your scary predictions so far into the future that no adult alive today will live to see if those predictions are true.”
“Thou shallt only use computer models which imperfectly match reality and are pre-programmed to produce a doomsday result.”
As ‘climate science’ unravels, so the predictions will become ever more dire.
It could very well be the national flag of Freedonia.
Michealwiseguy,
We admit there is climate change due to natural causes, especially solar cycles.
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.
So, only three models got inside the range of observations. The rest are no good. Except the three don’t fit inside the range of sensitivy we can glean from global temp records. Better chuck them too.
Seriously though, why don’t they check against the real world more frequently?
The idea seems to be that human sourced CO2 causes warming which reduces relative humidity and leads to less clouds thus allowing more incoming solar energy to warm the Earth even more.
That is different from the usual contention which relies on human CO2 plus a positive feedback from more water vapour keeping solar energy within the system for longer.
They are trying to incorporate into AGW theory the observation that cloudiness decreased during the warming period of the last century. That is necessary because it has been contended that the observed warming was due to reduced cloud cover and not more CO2. They need to cover both bases.
Puzzling then that global cloudiness and albedo seem to have been increasing since around 2000 with less solar energy entering the oceans despite CO2 still increasing.
Besides, global equilibrium temperature is linked to surface atmospheric pressure and not the amount of GHGs.
It is well known that water exposed to a vacuum rapidly converts to vapour without the addition of any extra energy.
The reason for that phenomenon is that as pressure is reduced towards a vacuum the amount of energy required to fuel the evaporative process falls below the amount of energy already stored within the water so as to keep it in liquid form rather than as ice.
That simple incontrovertible fact is absolute proof that the energy cost of evaporation falls with reducing pressure and rises with increasing pressure.
It is the energy cost of evaporation (set by surface atmospheric pressure) at a given level of solar input that determines the temperature that the oceans must reach in order to achieve thermal equilibrium and the ocean temperatures control air temperatures.
AGW theory is thereby killed stone dead because more GHGs cannot affect ocean equilibrium temperature (unless thay also affect atmospheric mass and surface pressure) but only the air circulation above the surface and even then not to an extent discernible as compared to natural oceanic and solar variations.
The circulatory changes between MWP and LIA and between LIA and today and between ice ages and interglacials give a good idea of the circulatory changes that can arise from natural processes alone.
But…the heat’s still missing! I saw a picture of it on a milk carton yesterday!
Sounds like it’s still models all the way down…
V good point from
“Urederra: If science were settled, it would not be necessary to have several climate models. One should be enough. ”
If the science is settled, why is anybody still playing with models at all?