Cloud cover is a major forcing, and uncertain, say researchers from the Hebrew University, US and Australia
Jerusalem, Jan. 26, 2014 – The warming effect of human-induced greenhouse gases is a given, but to what extent can we predict its future influence? That is an issue on which science is making progress, but the answers are still far from exact, say researchers from the Hebrew University of Jerusalem, the US and Australia who have studied the issue and whose work which has just appeared in the journal Science.
Indeed, one could say that the picture is a “cloudy” one, since the determination of the greenhouse gas effect involves multifaceted interactions with cloud cover.
To some extent, aerosols –- particles that float in the air caused by dust or pollution, including greenhouse gases – counteract part of the harming effects of climate warming by increasing the amount of sunlight reflected from clouds back into space. However, the ways in which these aerosols affect climate through their interaction with clouds are complex and incompletely captured by climate models, say the researchers. As a result, the radiative forcing (that is, the disturbance to the earth’s “energy budget” from the sun) caused by human activities is highly uncertain, making it difficult to predict the extent of global warming.
And while advances have led to a more detailed understanding of aerosol-cloud interactions and their effects on climate, further progress is hampered by limited observational capabilities and coarse climate models, says Prof. Daniel Rosenfeld of the Fredy and Nadine Herrmann Institute of Earth Sciences at the Hebrew University of Jerusalem, author of the article in Science. Rosenfeld wrote this article in cooperation with Dr. Steven Sherwood of the University of New South Wales, Sydney, Dr. Robert Wood of the University of Washington, Seattle, and Dr. Leo Donner of the US National Oceanic and Atmospheric Administration. .
Their recent studies have revealed a much more complicated picture of aerosol-cloud interactions than considered previously. Depending on the meteorological circumstances, aerosols can have dramatic effects of either increasing or decreasing the cloud sun-deflecting effect, the researchers say. Furthermore, little is known about the unperturbed aerosol level that existed in the preindustrial era. This reference level is very important for estimating the radiative forcing from aerosols.
Also needing further clarification is the response of the cloud cover and organization to the loss of water by rainfall. Understanding of the formation of ice and its interactions with liquid droplets is even more limited, mainly due to poor ability to measure the ice-nucleating activity of aerosols and the subsequent ice-forming processes in clouds.
Explicit computer simulations of these processes even at the scale of a whole cloud or multi-cloud system, let alone that of the planet, require hundreds of hours on the most powerful computers available. Therefore, a sufficiently accurate simulation of these processes at a global scale is still impractical.
Recently, however, researchers have been able to create groundbreaking simulations in which models were formulated presenting simplified schemes of cloud-aerosol interactions, This approach offers the potential for model runs that resolve clouds on a global scale for time scales up to several years, but climate simulations on a scale of a century are still not feasible. The model is also too coarse to resolve many of the fundamental aerosol-cloud processes at the scales on which they actually occur. Improved observational tests are essential for validating the results of simulations and ensuring that modeling developments are on the right track, say the researchers.
While it is unfortunate that further progress on understanding aerosol-cloud interactions and their effects on climate is limited by inadequate observational tools and models, achieving the required improvement in observations and simulations is within technological reach, the researchers emphasize, provided that the financial resources are invested. The level of effort, they say, should match the socioeconomic importance of what the results could provide: lower uncertainty in measuring man-made climate forcing and better understanding and predictions of future impacts of aerosols on our weather and climate.
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Blah, blah blah
More rubbish
Link to the abstract for this paper in this post, which says “”the radiative forcing (that is, the perturbation to Earth’s energy budget) caused by human activities is highly uncertain, making it difficult to predict the extent of global warming.”
Settled Science: New paper finds effect of man on climate is “highly uncertain”
http://hockeyschtick.blogspot.com/2014/01/settled-science-new-paper-finds-effect.html
As mentioned at a few places before, the “consensus” crowd is about to hijack the concepts they dismissed only a few months ago. Everything in order to maintain window view on a gravy express.
Next step will be “disappearing” of their AGW legacy, so we better start accumulating their mischiefs while they are still there.
Until we can model cloud formation – we have no GCM model. I don’t understand the debate on this. Where have I gone amiss? GK
Ma Nature says you blew it
The masses know it
Scramble Scramble Scramble
Here’s another excuse
Well so far, according to Hansen’s models ate least, the world has not noticed that CO2 has risen recently.
Still tiptoeing gently down the Scenario C dotted line = no forcing = <1.0C per doubling 🙂
http://snag.gy/FeWzn.jpg
These guys lose me in their first sentence: “The warming effect of human-induced greenhouse gases is a given…………” Do they actually think that one molecule of CO2 out of 2,500 molecules of air makes any difference? And man was responsible for 3-4% of that one molecule! They are barking up the wrong tree.
Anyone got a direct link?
Often wondered about strictly the change in atmosheric density for retaining heat. Aside from any given molecule’s wave length absorption of heat, denser gasses have more heat at the same temperature.
If that standard applied, co2 would make little difference because of its low concentration… while plentiful h2o has a real impact on heat.
Sounds like they are excited about their models and now need additional funding to run them and, oh, get a preindustrial aerosol baseline.
” … achieving the required improvement in observations and simulations is within technological reach, the researchers emphasize, provided that the financial resources are invested …”
See attached grant application.
“To some extent, aerosols –- particles that float in the air caused by dust or pollution, including greenhouse gases …”
Watch out for those CO2 particles! They’ll put your eye out!
I notice Sherwood is a co-author. Only a few weeks ago he was saying that climate sensitivity was 4 degrees based on his work on how clouds are formed. Now he is saying clouds are uncertain.
HenryP says:
January 27, 2014 at 12:15 pm
Blah, blah blah
More rubbish!
Blah, blah blah is translated to– Please send more money for studies for the next (?) years so I can retire before we have to find an answer that holds up under scrutiny.
Final para: ‘While it is unfortunate that further progress on understanding aerosol-cloud interactions and their effects on climate is limited by inadequate observational tools and models, achieving the required improvement in observations and simulations is within technological reach, the researchers emphasize, provided that the financial resources are invested. The level of effort, they say, should match the socioeconomic importance of what the results could provide: lower uncertainty in measuring man-made climate forcing and better understanding and predictions of future impacts of aerosols on our weather and climate’.
Having at last accepted that the science isn’t settled, the AGW zealots now want a pile of money to attempt to resettle it. Meanwhile economies are being screwed and people being impoverished as politicians, to lazy to ask the key questions of these madmen, behave like gaderine swine.
Jerusalem, by William Blake:
And did those feet in ancient time
Walk upon England’s mountains green?
And was the Holy Lamb of God
On England’s pleasant pastures seen?
And did the countenance divine
Shine forth upon our clouded hills?
And was Jerusalem builded here
Among these dark satanic mills?
Bring me my bow of burning gold!
Bring me my arrows of desire!
Bring me my spear! O clouds, unfold!
Bring me my chariot of fire!
I will not cease from mental fight,
Nor shall my sword sleep in my hand,
Till we have built Jerusalem
In England’s green and pleasant land.
But we must act NOW!!! Before it’s too late…err before the general public catches on.
“Explicit computer simulations of these processes even at the scale of a whole cloud or multi-cloud system, let alone that of the planet, require hundreds of hours on the most powerful computers available. Therefore, a sufficiently accurate simulation of these processes at a global scale is still impractical.”
I am not so convinced it is impractical to get useful information from a relatively simple model – it depends on what is being modeled.
The atmosphere (as discussed and dissed many times on WUWT) operates as a large heat engine (not ‘like one’ it is one). It strikes me as true that radiative models generally describe what would happen if the earth were really, really small and the atmosphere retained its normal viscosity. By that I mean some models assume radiative heat transfer dominates the movement of heat from the surface to the TOA. Verbal models of ‘how CO2 works’ describe radiative energy transfer, in the absence of mass transfer (updrafts)
In normal life the major portion of heat transfer in such a system is by convection. The FEA models for convective heat transfer between a hot and cold place with the heat applied at the bottom are pretty good. The ‘atmosphere’ breaks automatically into cells that circulate vertically air powered by heat and operating as a set of thermosiphons. The size of the cell is determined by the temperature difference and the properties of the fluid (in this case air, which is a fluid) and the vertical height. The property ‘viscosity-height’ is a major factor in the characteristic shape of things to come.
I realize ‘clouds’ covers a lot and I am sure they are going to take ages to model them in detail, but we would be far better off treating the atmosphere as a convection problem ‘with complexities’ than as a radiative physics problem with ‘impossibly complex factors that are also there’. We need a better two or three box model that is convective at the bottom and radiative at the top.
Ms. Climate’s relationship status on Facebook is “It’s complicated.”
“G. Karst says:
January 27, 2014 at 12:20 pm
Until we can model cloud formation – we have no GCM model. I don’t understand the debate on this. Where have I gone amiss? GK
#################
by assuming that you have to model everything to have a model that is useful to someone for some purpose.
Suppose you have a model of a car. You model everything except the change in tire air pressure as a result of the tire heating up. You could say your model depicted a tire filled with a gas like argon or nitrogen ( that’s what we used to limit tire expansion under heating)
Any ways you have this model that is missing a key feature. It will still be pretty good for many uses. For example, if you want to test some simple aerodynmic changes to the body.
You think the problem is black and white. No cloud formation= no model. Working scientists and working engineers dont necessarily think that way. They think.. what’s the best I can do, and then, how good is it, and then is it good enough for some purpose even if that purpose is limited.
meanwhile naysayers never build anything and say shit like man will never fly
“The warming effect of human-induced greenhouse gases is a given, but to what extent can we predict its future influence? That is an issue on which science is making progress, but the answers are still far from exact, …”
What is “a given”? How can something be declared “a given” when the next thing stated is “but the answers are still far from exact”? Where was it proved CO2 does anything but make plants grow?
How can anyone determine whether this is “progress” or just more climate change political hype?
“If the answers are still far from exact” as they say, what purpose does this announcement serve other than to keep “greenhouse” gases on center stage, to give “deniers” “pause” in criticizing climate change politics? This paper appears to serve the purpose of creating cognitive dissonance.
What is “a given” is that these people from the Hebrew University in Jerusalem are full of it. There is NO extent that they or we or anyone can predict its (AGW) future influence! NONE. The CAGW crowd has had three decades to demonstrate any skill whatsoever and they’ve FAILED miserably. If we are “given” any climate model results from them, we’d better be “given” the code and data so we can reproduce the same “results” exactly. Otherwise humanity will be fooled again – “exactly”.
“””””……Link to the abstract for this paper in this post, which says “”the radiative forcing (that is, the perturbation to Earth’s energy budget) caused by human activities is highly uncertain, ……”””””
I must be dreaming !
“””””…..(that is, the perturbation to Earth’s energy budget) …..””””””
No; it isn’t possible they might be thinking of atmospheric trace molecules (in all three phases) interfering with incoming solar energy. They do actually mention clouds, which are water (H2O) in the liquid and/or solid phases, But then they talk of “sunlight” reflected back into space.
Presumably they are some sort od scientists, with at least a rudimentary knowledge of physics.
So I’ll forgive them for equating “sunlight” with solar radiant energy. Sunlight is lumens, and it is all in my head. (eyes if you like) Solar radiant energy is in Joules, and only some of it is visible, and can produce the psycho-physical response of “light” in your brain; but I’ll let that pass.
But then they go on to assert that clouds REFLECT the sun light/energy. Well with a refractive index in the 1.333 range, water does reflect about 2% per surface, so there is some reflection; but not the 80% claimed. It is actually ordinary scattering through quite linear multiple optical refraction. I’ve ray traced a rain drop in near collimated incident rays, so many times, I can draw it in my sleep. Just two or three sequential wide angle refractions is enough to render the scattering virtually isotropic.
Now this direct interaction of the clouds with solar energy, is quite different from their interaction with the surface emitted LWIR radiation. That is virtually all absorbed (>95%) by droplets bigger than about 50 microns diameter (2 mils). So subsequently, it is re-emitted, as a BB like thermal spectrum, characteristic of the cloud Temperature. Once again this is isotropic emission, so half of it is still directed towards space.
But I didn’t see much talk about the absorption of incoming solar energy, by the water vapor, even in CAVU conditions. (Clear Air, Visibility Unlimited).
So you can squirm about “aerosols” and cloud formation, all you like; but mox nix; even if clouds don’t form, the INCREASED atmospheric WATER VAPOR due to any surface warming, will result in an increased absorption of the incoming solar spectrum energy; which thus will not reach the ocean surface to be stored in the deep.
No dancing, can avoid, that this is a negative feedback; regardless (or irregardless) of whether clouds are increased.
(some) Physicists understand what we really mean, when we talk of “sunlight”, and we know what we really mean when we talk of “reflection” ; but it only confuses the lay reader, when we misuse those words, when describing atmospheric effects.
Clouds do NOT (significantly) REFLECT solar spectrum energy; they scatter it by wide angle refraction. They also do NOT (significantly) REFLECT surface emitted LWIR radiation. They absorb it, and then re-radiate.
So what exactly are these Terra-computer models actually modeling, if these folks don’t know the correct words to use ?
They are sneaking up on Willis’s heat engine. CO2 is trumped by the operation of the heat engine.
wws at 1.07pm says
‘Jerusalem by William Blake’
This a particularly apt reference, as Blake, though not an atheist, was apalled by the power of organised religion. Some scholars believe that his reference to dark satanic mills relates to the spires of Oxford University where much of the hierachy of the Anglican church was educated and was its seat of academic power.
Very analogous to the role of the IPCC in relation to the CAGW religion.
Did anyone notice? The authors contradict themselves. How can something be both “impractical” and “within technological reach”
“Therefore, a sufficiently accurate simulation of these processes at a global scale is still impractical.”
“achieving the required improvement in observations and simulations is within technological reach”