Clouds: The Wild Card of Climate Change

There should be very interesting discussions and debates on this topic. I remember Dr. Roy Spencer said that from his initial studies, there is a negative feedback of clouds and water vapor on initial warming by man-made GHGs.

My thought is rather simple in that all clouds have an albedo effect. The pro AGW thought is that the net effect is positive, some clouds warm, some cool, some are neutral, depending I suppose on the relative changes in LWIR and SW which reach the surface. The idea being that the clouds increase the residence time of LWIR in the atmosphere while the vast majority of SWR continues to the surface.
My thought is that not all photons are equall due to their relative residence time in earth’s system, both ocean and amotsphere. So a cloud that blocks 5 W/m’2 of SWR through albedo, but has a 15 W/m’2 warming effect through the GHG effect will warm the atmosphere, but do to the far longer residence time of SWR photons entering the ocean the reduction of those 5 W/m’2 reduced SWR will have a stronger long term effect which is cumlitive depending on the duration of the change in cloud cover, and certainly as Stephen Wilde expresses, their laditude, which as they shift poleward obviously effects an ever greater % of the TSI. Ans so some clouds may indeed cause a short term atmospheic warming, but a longer term ocean cooling.
I definitely do not have the numbers to quantify the effect I am considering, primarily because I do not know the residence time of SWR photons entering the ocean vs the residence time of LWIR in the atmosphere. Any help here is appreciated.

david says:
November 5, 2010 at 4:57 am
“So a cloud that blocks 5 W/m’2 of SWR through albedo”
is hardly a cloud.
Fixed that for ya. Cloud top albedo is on the order of 80%. That means it reflects 80% of the light from the sun straight back out into space. That’s closer to 500 watts per square meter than it is to 5 watts. At night they reflect less than 50% of the upwelling long wave radiation back towards the surface and to make it even more unbalanced clouds tend to form in the morning and early afternoon and dissipate in the late afternoon and early evening.
The only “mystery” is exactly how unbalanced the situation is on a global average basis but there’s no credible doubt that clouds have a large net cooling effect. There’s also no doubt that there are more clouds when it’s warmer and fewer when it is colder. So if there is any additional forcing (more surface heat) from higher CO2 level this results in more clouds which will negate the additional forcing from CO2.
The ONLY significant greenhouse effect from CO2 is that first 100ppm or so raises the average temperature of the earth from below freezing to above freezing which activates the water cycle. Once the water cycle is active it takes over the regulation of surface temperature through negative feedback. The only thing to fear is when CO2 is not enough to keep the surface temperature above freezing. When that happens the water cycle effectively screeches to a halt and the surface gets covered with snow which also reflects 80% of the sun’s light and thus fosters even colder surface temperatures and even more snow in a vicious cycle of falling temperatures.
Evidently the pre-industrial level of 280ppm CO2 isn’t enough to stop the brief interglacial periods from ending as for the past several millions of years the earth is largely covered by glaciers 90% of the time. One can only pray that an anthropogenic driven doubling of CO2 to 560ppm or even a quadrupling to 1100ppm is enough to indefinitely extend the Holocene interglacial. If not then human civilization is in for big trouble. Imagine glaciers two miles thick covering all land surfaces from Washington, D.C. northward and land south of that having harsh winters instead of being above freezing all year round.
Hastening the end of the Holocene interglacial by reducing CO2 emissions is utter insanity.

“The role of clouds is enigmatic because clouds can exert opposing forces: Some types of clouds help cool the Earth and some types of clouds help warm it”
Well that certainly clears up the certain uncertainties!!!
What we don’t know is amazing !!

David Springer is absolutely right.

Anytime a cloud comes between the sun and the earth, there is an immediate and noticeable drop in temperatures, that increases the lower a cloud is. That can only mean that the albedo-enhancing effect dominates the heat trapping effect by quite a large margin, so during the day, clouds are a negative feedback.
When the sun isn’t shining however, clouds do keep things warmer than they would otherwise be, therefore they could be said to have a positive feedback effect at nighttime.
Overall, given the same amount of clouds at night and day, the effect would be negative, because they are reflecting away a lot more energy than they are retaining. I’ve never noticed a rise in temperatures at nighttime when a cloud comes over as much as the drop in temperatures in the daytime.

Whenever I see a straight line I know that I am looking at an artifact. When I see a feedback loop I know that I am looking at a computer programme. If nature allowed continuous looped feedbacks, the universe would have burned up billions of years before we were born.

From “Prof.” J. Collins:
“I’ve looked at clouds from both sides now,
From up and down, and still somehow,
It’s cloud illusions I recall,
I really don’t know clouds, at all. ”
A “golden-oldie” still good today!

Dave Springer says:
November 5, 2010 at 5:57 am
“There’s also no doubt that there are more clouds when it’s warmer and fewer when it is colder.”
I need to qualify that, Dave.
It’s certainly true locally (after a short period of adjustment when perversely the opposite applies as the system plays catch up with the temperature change) and perhaps regionally, but globally ? There’s the rub.
The evidence from the Earthshine project is that cloud quantities decreased during the recent warming spell and are now increasing with the cessation of warming and perhaps beginning of cooling. Likewise albedo.
http://bbso.njit.edu/Research/EarthShine/literature/Palle_etal_2006_EOS.pdf
So how could that be ? Strange how so many observations are turning out to have the reverse sign from standard expectations isn’t it ?
I would explain it by reference to the shifting of the jet streams and thus the associated cloud bands latitudinally.
At the same time as the albedo and cloudiness trends reversed in the late 90s I noted that the jets were starting to shift back equatorwards.
So my bet is that in shifting equatorward the cloud bands were stretched along a greater global circumference, increasing the length of the air mass boundaries and allowing more air mass mixing to produce more clouds.
Additionally the equatorward shift makes the clouds more reflective since they block higher intensity insolation.
That is what primarily causes global albedo changes and thereby changes the amount of solar shortwave able to penetrate the oceans.

Any ‘proper’ cloud reflects most of the sunlight back out into space. As this radiation never actually gets to the surface clouds by definition cool the Earth. Do we have decent records of Earth albedo from projects such as Earthshine and the many satellites we have orbiting us?

massive ice growth in arctic LOL
see DMI