New Cloud Model impacts AGW math models (for the worse)

I'm highly skeptical that climate models will ever be able to accurately depict cloud cover decades in the future, based on my experience with NWP models.

Aviation forecasts are very challenging with respect to cloud cover (ceilings) because the NWP models do such a poor job of projecting cloud cover, even just hours in the future.

 

By 2200, most of us will be already DEAD!
But we will probably have Flying Cars!

Damn, I miss all the fun!

 

I would say the research is highly problematic, since alley has empirecally found that the average sensitivity has been 2.8 in the paleo record. To say that you are cutting off the expected range to not include this number is highly problematic, and shows that whoever wrote this paper has not looked at the historical record to predict the future.

 

I have to admit some confusion about one of the lay reports:

Source: Solution to cloud riddle reveals hotter future: Global temperatures to rise at least 4 degrees C by 2100

The suggestion is the non-rain forming clouds are a water vapor transport system and the formation of '15 km' high thunderstorms are associated with a cooling or heat rejection system. Not stated is an observation I've seen that overcast, non-rain clouds are associated with warmer ground temperatures. Without the original article, $35, this is all I'm getting from this National Geographic summary with my speculation about the blanket effect.

Another effect of low clouds would be solar heat would convert to IR low enough that the CO{2} blanket effect would be nearly identical to heating the earth's surface. But this begs the question of how effective is the CO{2} blanket as a function of altitude. For example the SOFIA mission uses a 747 to get an IR telescope above most of the CO{2} and some of the high mountain observatories also exploit the lower concentrations of CO{2}.

Now the summary suggests the current models are not dealing with the low versus high clouds in their their thermal, earth heat transport models. If so, this would suggest correcting the models for the observed cloud coverage distribution would increase the earth's heat capture from the low clouds and reducing the cooling effects of upper atmosphere, 15 km, high rain clouds.

Bob Wilson

 

[quote="wjtracy, post: 1938852, member: 17892"So I am a natural Edisonian thinker, need to see real data, not a model. But in his case, there is no lab experiment that can answer the question.[/quote]

We are currently running that exact experiment. We will know soon enough what the result is. The real question is WHY are we running this experiment?

 

Can't even open the AGU blog link
But this refers to the Sherwood et al paper in Nature on January 2nd.
doi:10.1038/nature12829
It is available w/o paying $35 via your library, email Sherwood, or PM me.

I am not able to assess the value of the research contribution, but I share AG's concern that paleoproxies do not leave much 'room at the top' for increased IR sensitivity. Seems that Sherwood has just excluded the low end of the range, not extended the upper.

In any case, as we saw with Cowtan and Way, this is discomfiting and will lead to some sort of pushback.

BTW, SOFIA telescope has more trouble with water vapor than CO2

 

My bad! Still, it is good to get a telescope above most of the atmosphere even if on a nice, flexible, 747 . . . <grins>

The summaries of the paper are interesting and I'm hoping our resident weather expert might have some insights about cloud cover and thermal effects.

Bob Wilson

 

Bob,

Agree with you that low stratus can often cause a "blanket effect" and keep temps up especially during nocturnal hours. However, they also reflect incoming solar radiation (insolation) to some extent during diurnal hours (i.e., hold down daytime max temps), so the net effect might be near zero (not really sure about that).

As far as low clouds converting insolation to IR, it's probably most likely that the clouds simply reflect the insolation (mostly in the UV and visible light spectrum).

There's also no mention of high-level clouds like cirrus. Many reports I've seen suggest that very high cloud layers have a net warming effect, but that's not my experience. An unexpected cirrus shield seems to negatively affect daytime max temps much more than it moderates temps overnight.

One more point. The linked article in the OP states...

The implication is that it's an either/or proposition. That's actually not the case; there are many intermediate possibilities like over-running events (isentropic lift) which can cause widespread light to moderate rain events from nimbostratus clouds. These clouds are generally not very "thick", but nevertheless produce copious amounts of rain in some events.

 

Double post.

 

I remember a report after the USA airspace was shutdown that the absence of contrails led to a detectable, decrease in surface temperature. An interesting speculation, it wasn't one that I pursued with any vigor. I can believe there are a lot of cloud effects we've not yet fully plumbed.

Good point. I also asked Mr. Google and found some interesting papers on cloud density but soon it was nap time and I went to bed. But most the these papers were since 2011, suggesting it is an area receiving more attention.

Bob Wilson