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)
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Phillip Bratby is correct. The output of the models is not data. Data is a measured physical phenomenon.
“The tropical cu-nims happen every day, they suck enormous amounts of surface heat up into Hadley cells for more efficient cooling and they continue their cooling effects into the night. It seems obtuse of the researchers to consider a relatively rare cloud type when there is a very obvious everyday cloud type, the tropical cu-nim, that plainly does an awful lot more to our daily heat account and badly needs understanding.”
Spot on.
Also…the stratiform clouds are partially due to the cold California Current. . Of course they tend to go away when that portion of the ocean heats up.
And when it does….the ITCZ even has a better chance of ejecting monster amounts of heat energy towards the higher latitudes via tropical cyclones….so it all balances out in the end.
CHRIS
Norfolk, VA, USA
As Gary Plyler suggests, it’s possible that the cause and effect in this study has been reversed, as mentioned in the following article by Dr. Roy Spencer:
“When researchers observe natural changes in clouds and temperature, they have traditionally assumed that the temperature change caused the clouds to change, and not the other way around. To the extent that the cloud changes actually cause temperature change, this can ultimately lead to overestimates of how sensitive Earth’s climate is to our greenhouse gas emissions.
This seemingly simple mix-up between cause and effect is the basis of a new paper that will appear in the “Journal of Climate.” The paper¹s lead author, Dr. Roy W. Spencer, a principal research scientist at The University of Alabama in Huntsville, believes the work is the first step in demonstrating why climate models produce too much global warming.”
http://www.sciencedaily.com/releases/2008/06/080611184722.htm
And then we have these findings concerning cirrus clouds, again by Dr. Spencer:
“All leading climate models forecast that as the atmosphere warms there should be an increase in high altitude cirrus clouds, which would amplify any warming caused by manmade greenhouse gases,” he said. “That amplification is a positive feedback. What we found in month-to-month fluctuations of the tropical climate system was a strongly negative feedback. As the tropical atmosphere warms, cirrus clouds decrease. That allows more infrared heat to escape from the atmosphere to outer space.”
“While low clouds have a predominantly cooling effect due to their shading of sunlight, most cirrus clouds have a net warming effect on the Earth,” Spencer said. With high altitude ice clouds their infrared heat trapping exceeds their solar shading effect.”
http://www.sciencedaily.com/releases/2007/11/071102152636.htm
So once again warmists are trying to extrapolate catastrophe from the episode of warming in the late 20th century. There is still a lot of things to be explained.
1. Was it a reduction in clouds that caused this warming, or was it the warming that caused a reduction in clouds? Chicken and egg arguement.
2. If this is an example of positive feedback, why then did it not create a tipping point for accelerated warming? Climate hystersis anyone?
3. Why is it that the oceans are currently cooling, which indicates a large natural cyclical process? Indeed why is it this entire planet cooling, all contrary to every GCM employed?
If theres no lag between reduced cloudines and heating this is will make a good proof for Svensmarks hypothesis. If heating lags reduced cloudines the fit is even better. If its the other way around Svensmark is in trouble. Is there any information on this issue in the paper?
Heat from the ocean raises the dew point of a parcel of air so it holds more moisture/ latent heat.
The atmosphere then stirs the pot to try an balance out the energy imbalances.
Eventually the parcel of air cools to below the dew point by any number of mechanisms and the moisture precipitates as cloud out which would further cool the air.
Is this not a question of weather rather than climate?
For more than 20 years, I have had a VERY SIMPLE thought related to climate variability that I just can’t let go, regardless of how models operate. So, I’m going to throw this out there…
When the world warms, due to some change in overall radiative balance (whether it be due to changes in atmospheric and oceanic circulation or whether it be due to changes in solar effects or even… hehem… greenhouse gases), there is less cloud until a new equilibrium is reached, simply because the air warms faster than the water vapour content increases and relative humidity drops (despite the very slow increase in absolute humidity). With lower RELATIVE humidity, there is less cloud until a new equilibrium is reached. I have ALWAYS thought that a warming world (not just ocean) would NOT increase cloudiness, but, rather TEMPORARILY DECREASE it. This is NOT a vicious cycle in the long term, because, eventually a new equilibrium is established with a more or less similar global cloud cover.
When the world cools, there is more cloud on a global average basis, because a slightly higher proportion of the atmosphere hits the dewpoint during the cooling and it takes time to rain/dew out the extra moisture. Again… not a vicious cycle for long, as a new equilibrium is established with similar global cloud coverage.
This would explain the observation in this paper. This would also explain the solar amplicification effect (even without cosmic radiation effects). Maybe a change from 1367 to 1361 W/m2 isn’t a big deal until the very slight cooling causes more cloud and it cools more. The reverse would be true as well.
I meant “amplification”. Can dyslexia set in during middle age?
Low altitude cloud layers—decreased in the study area as ocean temperatures rose and atmospheric pressure fell.
Less low altitude cloud = more early morning sunshine = shorter time for net radiative cooling in the early morning = higher Tmin
This is further evidence that increasing Tmin – most of the claimed global warming – is due to increased early morning sunshine, not reflected in temperatures over the rest of the day.
Ie, most of the ‘global warming’ is an artifact of how ‘global warming’ was measured. Which explains why most of it dissapeared when the satellite data became available.
OT but breaking news, NZ government has announced a target of 20% reduction of GHG by 2020. Not sure if that is from 1990 levels or from now but it probably doesn’t matter. They claim it will only add $NZ60.00 per annum to the average household. Let me be the first to call BS on this. NZ are doing the EU trick of promising to do something while doing nothing. But they are going to tax us a bit just cause they can. Greenpeace had a campaign to suggest 40% reduction by 2020. This was laughable because livestock methane emmissions account for 50% of our GHG. To achieve a 40 % reduction without killing all the sheep and cattle in nz would require an 80% reduction in CO2 emissions.
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?
The best way to test the cloud relation to warming would be to compair average cloud cover on the equator to some constant reference point away from the equator??
Being warmer at the equator, we can tell if there is more or less cloud.
One could then use that compairison to judge how a warmer planet would react. If there are less clouds at the equator, global warming will runn out of controll. If there are more clouds at the equator, one would have to assume negative feedback dominates the basic process.
My vote is for negative feedback. is this wrong?
If clouds amplify any warming, why hasn’t all the water on the planet been boiled off by now? There was about 4 billion years time to crank up the temperature through ever more clouds.
When I go to the beach I see that there’s a lot of water left.
The conclusion I draw is obvious.
There’s recent Russian study linking solar wind, cosmic rays and cloudiness in central antarctica:
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VHB-4TP49SX-1&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=b3a10e1f8a9306ef51668bae92298f66
Ah, those vicious cycles. And to think it all starts with the bubbles in the beer. I suspected as much…
And what is the effect of clouds at night ?
“The agreement we found between the surface-based observations and the satellite data was almost shocking,”
Maybe that is the purpose they had in mind. (Think Copenhagen)
—
rbateman:
“What is it that they are trying to do, hypnotize the world?”
Exactly.
Loved these quotes:
And:
Say what?
I’ve noticed that the wind never blows unless trees are wagging about. Who knew? Trees cause wind! At sea, I’m pretty sure the wind is generated by waves, particularly the white ones.
the modern maximum of the sun has lowerd the cloud cover and warmed the oceans. Its just the other way around.
“John in NZ (01:00:51) :
OT but breaking news, NZ government has announced a target of 20% reduction of GHG by 2020. Not sure if that is from 1990 levels or from now but it probably doesn’t matter. They claim it will only add $NZ60.00 per annum to the average household. Let me be the first to call BS on this. NZ are doing the EU trick of promising to do something while doing nothing. But they are going to tax us a bit just cause they can. Greenpeace had a campaign to suggest 40% reduction by 2020. This was laughable because livestock methane emmissions account for 50% of our GHG. To achieve a 40 % reduction without killing all the sheep and cattle in nz would require an 80% reduction in CO2 emissions.”
Strewth! I thought NZ was the only shining light of sense in the pacific with regards to AGW. Well, it is clear it is seen as a revenue stream, just like GST and road user charges on petrol/diesel, and the one-off short-term 4c p/l tax on fuel for Auckland only that the whole contry had to pay for and then GST. Yes, a tax (GST) on levies, charges and taxes. I understand that a tax on a tax was illegal in NZ, like GST of the TV license, which was abolished because someone won a case in court about it.
They appear to have discovered something quite earth-shattering: that it tends to be warmer when there are less clouds!
Seriously, there is an obvious question of cause-and-effect. This study does demonstrate a strong correlation between clouds and temperatures. But you have to be very careful to establish which is the cause and which is the effect.
The ice cores appeared to prove that temperatures were driven by atmospheric carbon dioxide. But we now know it was the other way round. When Gore said “When the carbon dioxide goes up, the temperature goes up” he should have said “When the temperature goes up, the carbon dioxide goes up”.
Of course the difficulty is that often things are both a cause and an effect. In the case of the ice cores, the temperature was probably controlled by carbon dioxide to some extent (giving rise to the dreaded positive feedback). But as it can’t be seen in the record (as far as I’m aware) then the effect of CO2 on the temperature must be very small and possibly negligible. So, although the correlation between CO2 and temperature over hundreds of thousands of years is extraordinarily strong, there clearly is no significant positive feedback.
Could a similar situation apply to temperatures and clouds? The fact that I’m sitting at my desk and writing this tends to suggest that negative feedbacks are dominant. If the global climate were dominated by positive feedbacks then there would probably be no human civilisation, no climate scientists, no Al Gore….
Chris
A few thoughts about Clement et al:
The area of the North Pacific chosen for study by Clement et al is identified in their supplemental materials as 15N-25N, 145W-115W. Refer to the text for Figure S1:
http://www.sciencemag.org/cgi/data/325/5939/460/DC1/1
Though they don’t display a typical ENSO signal, the SST anomalies for that area of the Northeast Tropical Pacific are strongly influenced by ENSO, as are trade winds, cloud cover, etc. The SST Anomalies from 1950 to present clearly show the 1976 Pacific Climate Shift. And they also show a positive trend (0.068 deg C/decade), a warming, which is consistent with the tone of the study.
http://i28.tinypic.com/qqbw4j.png
However, if we shorten the period to 1975 to present, the linear trend of the SST anomalies is negative (-0.056 deg C/decade).
http://i28.tinypic.com/2uft89k.png
During El Nino events, the cloud cover and precipitation follow the warm water from the Pacific Warm Pool to the Central and Eastern Equatorial Pacific. The increase in convection over the eastern equatorial Pacific during those El Nino events should impact the trade winds and cloud amount over the area studied. Would the low cloud cover be drawn toward the equator by the convection during the El Nino events?
New Zealand is a small player in a big world. Climate Minister Nick Smith has to balance what I suspect is his personal wish (do nothing) against the need to be seen to be ‘doing something’. Because NZ is highly trade dependent, we can’t afford to outrage critical markets. Tourism is a case in point. We attract a lot of tourists through the promise of ‘100 percent pure’, ‘Clean, Green NZ’. Some of our big markets (especially the segments that visit us) are highly conservation/green values sensitive.
We are already suffering reduced arrivals because of the global recession and are struggling against the northern hemisphere perception that a trip to NZ creates ‘a huge carbon footprint’. New Zealand simply cannot afford to be seen to be doing nothing and be pilloried or ostracised for its apostasy. It is the same with agriculture; we are facing the ‘food miles’ problem as well, even though NZ lamb on the English table generates less ‘carbon’ than its Welsh equivalent, distance notwithstanding.
The previous leftist government was evangelical about ‘carbon’; we were to be the first ‘carbon neutral’ nation ever, no matter the cost. The new government (centre right) is more sanguine. We are to be ‘cautious followers’, not pioneers. This, it seems to me, is cautious following and will never eventuate. The failure of other countries to honour their various extravagant commitments will allow us to weasel out as well, as reality strikes.
As for taxes on taxes – oh, yes! GST (Goods and Services Tax) applies to everything.
Even rates (local city taxes) attract GST.
I will be very interested to see what Roy Spencer has to say about this. It’s right up his street. He may say it’s the other way round – reduced cloud cover leading to rising sea temperature. The great fault of this study is that it is a static representation of the relationship between temperature and clouds and completely ignores the dynamic behavior of cloud formation and dissipation. A clue can be found in the sentence – “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”. You’ll notice there is no assessment of which role is dominant.
We know two things for certain. 1. Precipitation exactly matches evaporation, and 2. The atmosphere is not saturated with water vapor. Increased trade winds would cause increased evaporation leading to surface cooling and increased cloud cover. The extra moisture would come down somewhere as precipitation so cloud cover would be greater or thicker somewhere. Interestingly, if the atmosphere was saturated with water vapor then the positive feedback (dCo2 -> dT -> dH20vapor -> dT) would be true.
I’m not convinced by this study but it’s promising that mainstream scientists are finally researching and measuring clouds. They have yet to realize that the dynamic behavior of clouds is key.