This study is being listed as proof by some of the usual alarmist types that the issue of cloud feedback is settled. Before accepting that, read this from the summary in the June 24th issue of Science by Richard A. Kerr:
The first reliable analysis of cloud behavior over past decades suggests—but falls short of proving—that clouds are strongly amplifying global warming. If that’s true, then almost all climate models have got it wrong. On page 460, climate researchers consider the two best, long-term records of cloud behavior over a rectangle of ocean that nearly spans the subtropics between Hawaii and Mexico. In a warming episode that started around 1976, ship-based data showed that cloud cover—especially low-altitude cloud layers—decreased in the study area as ocean temperatures rose and atmospheric pressure fell. One interpretation, the researchers say, is that the warming ocean was transferring heat to the overlying atmosphere, thinning out the low-lying clouds to let in more sunlight that further warmed the ocean. That’s a positive or amplifying feedback. During a cooling event in the late 1990s, both data sets recorded just the opposite changes—exactly what would happen if the same amplifying process were operating in reverse.
Here’s the press release. I’ve looked at a few news writeups on it, and the caution listed in Science about it not being proven seems to be off the reporting radar. We’ll need further studies on a global scale, and not just one patch of ocean, before the question can be fully answered. – Anthony
From Physorg.com
The role of clouds in climate change has been a major question for decades. As the earth warms under increasing greenhouse gases, it is not known whether clouds will dissipate, letting in more of the sun’s heat energy and making the earth warm even faster, or whether cloud cover will increase, blocking the Sun’s rays and actually slowing down global warming.
In a study published in the July 24 issue of Science, researchers Amy Clement and Robert Burgman from the University of Miami’s Rosenstiel School of Marine and Atmospheric Science and Joel Norris from Scripps Institution of Oceanography at UC San Diego begin to unravel this mystery. Using observational data collected over the last 50 years and complex climate models, the team has established that low-level stratiform clouds appear to dissipate as the ocean warms, indicating that changes in these clouds may enhance the warming of the planet.
Because of inconsistencies in historical observations, trends in cloudiness have been difficult to identify. The team broke through this cloud conundrum by removing errors from cloud records and using multiple data sources for the northeast Pacific Ocean, one of the most well-studied areas of low-level stratiform clouds in the world. The result of their analysis was a surprising degree of agreement between two multi-decade datasets that were not only independent of each other, but that employed fundamentally different measurement methods. One set consisted of collected visual observations from ships over the last 50 years, and the other was based on data collected from weather satellites.
“The agreement we found between the surface-based observations and the satellite data was almost shocking,” said Clement, a professor of meteorology and physical oceanography at the University of Miami, and winner of the American Geophysical Union’s 2007 Macelwane Award for her groundbreaking work on climate change. “These are subtle changes that take place over decades. It is extremely encouraging that a satellite passing miles above the earth would document the same thing as sailors looking up at a cloudy sky from the deck of a ship.”
What was not so encouraging, however, was the fact that most of the state-of-the-art climate models from modeling centers around the world do not reproduce this cloud behavior. Only one, the Hadley Centre model from the U.K. Met Office, was able to reproduce the observations. “We have a long way to go in getting the models right, but the Hadley Centre model results can help point us in the right direction,” said co-author Burgman, a research scientist at the University of Miami.
Together, the observations and the Hadley Centre model results provide evidence that low-level stratiform clouds, which currently shield the earth from the sun’s radiation, may dissipate in warming climates, allowing the oceans to further heat up, which would then cause more cloud dissipation.
“This is somewhat of a vicious cycle potentially exacerbating global warming,” said Clement. “But these findings provide a new way of looking at clouds changes. This can help to improve the simulation of clouds in climate models, which will lead to more accurate projections of future climate changes. ”
One key finding in the study is that it is not the warming of the ocean alone that reduces cloudiness — a weakening of the trade winds also appears to play a critical role. All models predict a warming ocean, but if they don’t have the correct relationship between clouds and atmospheric circulation, they won’t produce a realistic cloud response.
“I am optimistic that there will be major progress in understanding global cloud changes during the next several years,” said Norris. “The representation of clouds in models is improving, and observational records are being reprocessed to remove spurious variability associated with satellite changes and other problems.”
Source: University of Miami (news : web)
It is extremely unlikely that the earth’s climate is net positive feedback. I am an electrical engineer. When we design an amplifier with negative feedback, it is linear. This means the output responds to changes in input by moving at the designed gain. This type of amplifer is used for example as an audio amplifer. When we want to design an amplifier as a switch, we add positive feedback. This causes the amplifer to sit at one rail until the input crosses the designed threshold. Then, it slews as fast as the amplifer can move to the other rail. It is obvious to anyone living on the earth that this does not describe the earth’s climate. A system with net positive feedback cannot by definition sit in a linear range. It has to sit at one of the rails. The earth’s climate would slew from “snowball earth” to Venus and back in response to inputs. Looking out my window, this doesn’t appear to be the case!
If you look closely at the above image of the cloud coverage, you can see a few linear features of thicker cloud in the darker area. My guess is that these are ship tracks. When the atmosphere is short of condensation nuclei, cloud formation is retarded. A passing ship leaves a trail of nuclei and clouds form along the track. Just imagine for a moment the difference in the power of the sun below those thicker lines and below the blue skies in the rest of the cloud depleted region.
I cannot access the paper. However, I’d be very interested in seeing if they have any data on the CCN status of the air mass they studied, pollution of cloud droplets by oil or surfactant, cloud droplet size etc etc. If temperature fluctuations have an effect on CCN production, then I’d expect much larger temperature effects than the tiny warming CO2 contribution. For those who doubt the efficacy of CCN reduction on the formation of boundary layer cloud, there is a noticable reduction of cloud amount, and a raising of the cloud deck, downwind of a major oil-spill.*
The key to the global warming debate is the 20% of the world’s surface covered by low level stratocumulus cloud, coverage which depends on wind-speed, surface pollution, sea temperatures, atmospheric dust and biological feedbacks. Until we have new research into the influence (if any) we have on that cloud cover, I’d not spend a green cent on carbon sequestration, cap and trade or any of the rest of the proposed solutions.
Let’s see what the problem is. Then deal with it.
JF
*I’ll do a search and see if I can find an account.
So they have data for warmer oceans and less cloud. This seems a little obvious to the non-expert. Less clouds means more sun means more warming of the ocean in their study area. What am I missing?
Another bud naked emperor.
Repeat after me: clouds cool, clouds cool, clouds cool. clouds cool, clouds cool…
Do you get it now.
Here is what I don’t get.
Obviously the results presented in this report supports the Svensmark effect, assuming that this is what happening.
These scientists, the climatologists don’t they seen the close correlation with C14 proxy and the global temperature and asked themselves..hm this is strange…why is that?
Might there be some connections between solar activity and the global temperature?
Are they not exposed to this data?
Or do they don’t want to see it or know anything about it?
They do not even know exactly how clouds effect climate change, but they have got this thing modeled to perfection?
This is totally absurd.
If I were a climate scientist, I wouldn’t be bragging too much at the moment. This is seriously turning into a joke. A pathetic one at that.
And what if it is the change in clouds that is causing the warming?
This is what Roy Spencer thinks to be the case.
“Together, the observations and the Hadley Centre model results provide evidence that low-level stratiform clouds, which currently shield the earth from the sun’s radiation, may dissipate in warming climates, allowing the oceans to further heat up, which would then cause more cloud dissipation”.
What if they have it reversed?
This study seems very evasive and heavily parsed. not to mention counter factual.
My bet is it goes in the heap with MAnn and Antarctica.
This appears to be one example where a computer model can start to model the effects of clouds.
i. In one part of the worldin the subtropics.
ii. During a period of 30 years.
It’s a start.
Let’s hope that this leads to:
i. More regions being studied.
ii. Open-ness to integrate data into models, new or current, not force-fitting into dogma.
iii. Questions about why cycles of cold-dry, hot-dry, hot-wet, cold-wet occur on some spots on earth, often through decades, not months, and how these nuggets fit into that.
Science is starting to emerge in this debate.
Long may that continue.
Sounds like they are just describing cloud behavior during El Ninos and La Ninas.
Low cloud cover is known to decrease in this area of the Pacific during and leading up to El Ninos and then increase for La Ninas.
The paper certainly should have taken this into account. What exact area did they study (and is the data actually correlated to the ENSO). The abstract and the summaries do not contain any detail.
Just The Facts (21:43:57) :
So we don’t understand how the clouds work and we don’t understand how the sun works, yet there’s supposed to be a scientific consensus on the long term trajectory of Earth’s temperature?
I think what they do understand is there is a paycheck connected to global warming.
Jack Hughes (21:44:39) : What does the output of a model look like ?
Like this : $
J.Hansford (22:14:49) : Plus, didn’t Prof Richard Lindzen describe this with his “Iris effect”?… But show it as a Negative feedback….?
It seems there are many commenters who still haven’t seen Roy Spencer on negative feedback in this 2 part YouTube series :
This is nothing new. They were studying El Nino. Slow trade winds allows the Sun to heat the top layer of ocean, leading to an El Nino. No cold fronts, no storm clouds, no choppy seas. That said, the weather clouds associated with this condition did not disappear. They track rather slowly along the Jet Stream off the southern coast of California, north of the area of the Pacific studied, and bring lots of rain. And then there is the reverse. Fast trade winds clear away warm waters and allow upwelling to occur leading to La Nina. This also shifts the Jet Stream (and now fast moving weather fronts, IE clouds), to its northern track, thus drying out California. So in essence, the study centered on the equatorial belt and its signal of El Nino and La Nina. The study has the correlation of warming and clouds ass backwards (possibly in an effort to “spin it” in order to satisfy the grant?). Trade winds, SST, El Nino/La Nina, Jet Stream position, warming/cooling.
One more thing. If seas are choppy from strong trade winds, my speculation is that a bit of water is kicked up into the atmosphere along with salt spray. This would explain visible low lying clouds in the area studied during La Nina.
Freddy . . . .
“…by removing errors from cloud records…”
Betcha this is going to be another data-torturing exercise with no statistical significance.”
Data Water Boarding is not torture according to the Warmonger Guide to Climate Hysterics. They are just having a little fun with the numbers, teasing them, a tickle here, a cajole there.
Of course low level clouds dissipate when sea surfaces warm. The warmer water heats the air which can then hold more water as vapour and low level clouds dissipate.
However the warmer air with more vapour in it then accelerates the hydrological cycle and not long afterwards convection kicks in with a higher cloud base and becomes more vigorous than it would have done at a lower temperature because of the increased temperature differential betweeen the surface and space.
Envisage a summer morning near the east coast of England with low cloud coming off the North Sea making it overcast. First the increasing warmth of the day burns off the low cloud. Then if the air is unstable along come cumulus then cumulonimbus and then cirrus. The increased convection in the latter half of the process reduces insolation far more than the burning off of the low level cloud increases it.
There is so much obvious ignorance being promulgated as so called peer reviewed science that I begin to despair.
The obvious question is – “Are the clouds cause or effect?”
Clearly they are assuming they are effect (water warms, clouds thin out) , but according to Svenmark’s hypothesis, wouldn’t they be cause (clouds change due to cosmic ray effects & ocean temperature reacts, which in turn effects atmospheric temperature)
This seems pretty fundamental – anything in the article about this?
If I understand the article correctly this statement sums up their findings:
“Together, the observations and the Hadley Centre model results provide evidence that low-level stratiform clouds, which currently shield the earth from the sun’s radiation, may dissipate in warming climates, allowing the oceans to further heat up, which would then cause more cloud dissipation.”
If this is the case, why don’t the clouds alone produce a runaway effect ignoring any influence from CO2? It should work like this; warming results in fewer clouds which causes more warming which causes fewer clouds still and more warming yet. Conversely, cooling would cause more clouds which would cause more cooling. It sounds like a very unstable system unless there are negative feedbacks to counter it.
It’s a bla, bla, bla, story and when finished there is this burning question!
Where is the EVIDENCE?
Anthony, please check the spam filter. I posted a comment about 3 hours ago and it hasn’t appeared yet. It had a couple of links, including SST anomalies for the area of the study (one shows a deceasing trend in SST anomaly from 1975 to present). I’ve got a copy, just in case it disappeared.
[REPLY – Done. (Fear not. We always check the spam filter.) ~Evan]
Did the reported decrease in cloudiness, perhaps due to variations in wind, atmospheric presure, dust particles, etc., cause the ocean’s surface water to warm, or did the reported warmer ocean water, due to ocean current, tidal, wind-activated whitecaps, atmospheric pressure variations, etc., cause the clouds to dissipate? In other words, which comes first in each case, the cause or the effect? When the skewed psuedo-science promoting AGW can honestly answer these quetions, I’ll agree that the issue is settled. Meanwhile, why should we let the politicized “scientists” in Congress stick the USA with a job-killing, economy-debilitating carbon tax based on a possibly/probably fallacious unproven climate theory?
It looks like a cart and horse issue to me. The researchers note that warmer temperatures correlate well to less cloud cover and assume that it is the warmer temperatures that are causing cloud cover to decrease. It seems to me that one can argue for the opposite; that it is the change in cloud cover that drives temperatures just as Svensmark predicted in his theory.
Dave Wendt (01:08:42) :
“I’m not really familiar with ship board weather logs. Would it be the norm for them to include specific cloud types and altitude and coverage estimations?”
Yes — most ship reports are quite similar to synoptic reports.
Old time (experienced) observers can generally deliver quite reasonable estimates of cloud base heights, but coverage estimation is less accurate. Observers can’t detect even large breaks in coverage as the layer approaches the horizon.
Also humans have a hard time estimating areas. If I remember correctly (and I don’t as often these days!) some old observing manuals would note that clouds approaching from the horizon toward the observer, and ending in a straight line at an angle to the observer of 45 degrees, would cover only 1/8th of the sky.