Do clouds have a negative or positive feedback when it comes to warming?

Water is the 900 pound gorilla in the room that alarmists always tend to ignore or brush off. The effect of water vapor and clouds is unknown. I tend to think it may act somewhat as a thermostat. Like the thermostat in your home, you can increase the insulation in your walls, but that doesn't mean your house is going to get significantly warmer unless you change the thermostat. Obviously it isn't that simple. Alarmist require warming from CO2 to increase water vapor. Alarmists require that there are no buffering effects from water and clouds on the climate. That assumption is a pretty wild assumption in my opinion. If it weren't, why wouldn't temperature just spiral out of control during past interglacial periods. There must be mechanism(s) that prevent that from happening. The climate went through multiple periods of increased temperature and CO2 concentrations yet always cooled and entered glacial periods.

To answer simply, scientist do not know.

Dana once again has it wrong. I love the self professed scientist who consistently make bad assumptions.

He is correct when he says we do not know for certain if the clouds are + or -. It is thought, but not proven, that higher clouds may be positive and low clouds negative.

He then goes on to make the usual unproven statement.

"...the only possible significant negative feedback is low cloudcover (which in fact may even be positive itself). "

First of all, saying the ONLY possible negative feed back is cloud cover is just silly. Any climate scientist will tell you that they do not know all the feedback and how they work. If they did, then their models would actually be able to correctly predict the future climate from any point in history (why the ice ages? why the current cooling? Why did the earth come out of ice age?, etc, etc).

then the 2nd grand assumption (and we know what assuming does),

"So I think it's abundantly clear that the net feedback is positive, and the climate is pretty darn sensitive to increasing CO2."

Nothing in current scientific studies supports this statement. It is not abundantly clear that there is more positive than negative forcing. What if the low cloud cover was so negative that it over rides all other forcings? And saying that climate is pretty darn sensitive to CO2 shows how little he really understands the climate and CO2. No current study supports the theory that temp is driven by CO2. You could say that CO2 is driven by temp and be more accurate as there are studies to support the theory. If CO2 is so powerful (it's not), then how does the temp drop as CO2 rises, whether in the 70's or now? It is a silly thing to say.

Making broad statements like these are why so many people are fed up with the current debate (or really a lack of debate). Science needs to provide proof of theories in order to become common knowledge. AGW is an unproven theory at best, yet the AGW loons want to close the subject to open debate. This would suggest they are unsure and scared about opening up the debate as they may lose public sentiment. If they were sure of the science, they would be demanding nation wide, televised debates on hte topic. Instead, they hide behind statements like Dana's and refuse an open debate. When was the last time a major TV station broadcast an open prime time debate? Answer, never.

As Conservative has stated, most feedbacks observed in nature are negative. In other words, nature tends to reach equilibrium states almost universally as opposed to runaway states caused by positive feedbacks. Although there are some minor positive feedbacks that eventually get negated.

I generally lean towards clouds having a negative feedback much the same way aerosols tend to increase the earth's albedo by reflecting UV radiation back into space. It does tend to get complicated though when we look at both high and low clouds and the entire globe rather than just over the ocean in the tropics as that sciencemag.com study is about.

Both, really it's easier to understand it as a loop system opposed to +/-feedback's. *Climate change-vs-equilibrium is an expression of time (see: "Younger Dryas").

http://www.globalchange.umich.edu/globalchange1/cu...

Deep mass circulation and black body radiation could also be listed as negative feedback's. You could read any two articles on this and come up with a different conclusion pro or con. Forcing and flux's haven't reached the level of total comprehensive understanding.

Twenty years ago, this question was in great doubt. No longer.

"New observational and modelling evidence

strongly supports a combined water vapour-lapse rate

feedback of a strength comparable to that found in

General Circulation Models (approximately 1 W m–2 °C–1,

corresponding to around a 50% amplification of global

mean warming)."

http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/a...

Clouds can keep winter nights cooler through retaining the days heat through the night. Clouds during the day can keep days cooler because they interrupt most of the suns heat only letting UV in while most of the rest out. So clouds depending on circumstances be either.

Spencer also believes in creationism. In fairness, cloud feeback uncertainty is large, and makes up most of the range in climate sensitivity estimates. A recent study from on region indicates it's strongly positive - higher than mean IPCC estimate.

http://www.sciencemag.org/cgi/content/full/325/593...

On your second question, the answer is "no". However, paleoclimatic studies indicate a strong net positive feedback. So if cloud feedback is negative, it's likely some other feedback has been underestimated, although most known feedbacks (besides clouds) are reasonably constrained. Methane clathrates are a possible exception.

http://www.grist.org/article/Negative-climate-feed...

We don't know yet. Some studies show it's positive, others negative.

http://answers.yahoo.com/question/index;_ylt=Ag0rs...

We do however know that methane released from melting permafrost and warming bogs, albedo (melting ice), biosphere and oceans (saturating with CO2), water vapor, and so on are all positive feedbacks, and the only possible significant negative feedback is low cloudcover (which in fact may even be positive itself). So I think it's abundantly clear that the net feedback is positive, and the climate is pretty darn sensitive to increasing CO2.

For those incorrectly arguing "most feedbacks observed in nature are negative" (Ottawa, conservatives), I challenge you to name two. It's all well and good to make these unsubstantiated claims that there are a bunch of negative feedbacks, but you can't name any. Just off the top of my head in my answer I named 6 strong positive feedbacks.

Clouds = water vapor. Water vapor = greenhouse gas.

Positive feedbacks are rare in nature.

The warmists would have us believe that the earth has been teetering on the brink for millions of years. Then man comes along and burns a log and the whole thing comes tumbling down.