Over 20 years ago, Ramanathan and Collins (1991 Nature, “RC91”) advanced what became known as the “Thermostat Hypothesis”, relating to how cloud formation over the tropical Pacific warm pool limits just how warm surface waters there can get. While this conceptual view was OK for the warm pool itself, they made some extrapolations which weren’t really warranted about what this meant for the larger-scale climate system, and ultimately whether “global warming” will be reduced by a resulting increase in cloud cover reflecting more sunlight back to space (negative cloud feedback).

Now, I will say that I believe that the climate system is stabilized by negative cloud feedback, even though most if not all climate models exhibit positive cloud feedback. But you have to be careful about what you use as evidence, and cloud formation over warm areas (e.g. at the end of this post at WUWT) is simply not evidence. Even climate models with strong positive cloud feedback (decreasing clouds with warming) are going to form clouds over warm areas of the oceans. That’s the way atmospheric circulation systems work.

The RC91 Thermostat Hypothesis paper, written by experts in radiation but not so much in atmospheric dynamics, was quickly attacked for neglecting the fact that, for all of that rising cloudy air over the warm pool, there has to be sinking air elsewhere which suppresses cloud formation.

In other words, just because clouds preferentially form over locations with warmer ocean waters doesn’t mean it’s evidence for negative cloud feedback (clouds increasing with global warming). Here’s a cartoon showing the basic idea:

Hartmann and Michelsen (1993 J. of Climate) and Lau et al. (1994 Geophys Res. Lett., 21, 1157-1160) were among the first papers to point this out. Much work has been done on the issue in the last 22 years with the general conclusion that, for the tropical oceans at least, warming leads to virtually no net cloud feedback, either positive or negative. The problem gets even more complicated because the temperature inversion in the above cartoon — the result of subsidence-warmed air overlying cooler ocean waters — also causes marine stratus clouds to form, which have a strong cooling effect on the climate system as a whole.

If the cloud feedback problem was that simple, it would have been solved long ago. But it ain’t that simple.

One of the oft-cited objections to the term “greenhouse effect” is that it is a misnomer, that a real greenhouse (you know, the kind you grow plants in) doesn’t work by inhibiting infrared energy loss. It is usually claimed that a real greenhouse works by inhibiting convective heat loss by trapping the sun-heated air inside.

While working on a new website devoted to answering greenhouse questions, I decided to examine this issue. What piqued my interest was a couple quick back-of-the-envelope calculations that (1) for a glass covered greenhouse, the downward infrared (IR) emission from the roof should be about 100 W/m2 more than from a clear sky (a pane of glass is high emissivity, and opaque to broadband infrared), and (2) the realization that a greenhouse generates its own convection from the roof because the glass heats up, so convective air currents inside have their heat conducted (albeit inefficiently) through the glass, then the warm glass of the roof causes its own convection.

Add to this the fact that greenhouses are usually vented, which means they lose heat convectively anyway that by-passes the greenhouse structure.

So, the question is: Does a greenhouse work more from infrared heating (the “greenhouse effect”), or more from the inhibition of convective heat loss?

First, let’s examine some approximate energy fluxes for vegetation in the summertime. These are only rough estimates, and there are rather large variations in these depending on cloud cover, etc., and to be meaningful they need to represent a day+night average (infrared fluxes are orange; solar are yellow; convective are blue):

For simplicity, the calculated IR emission from solid surfaces assumes an emissivity of 1. The downward sky infrared is consistent with the BSRN network measurements during the warm season. Note that the energy fluxes have to sum to zero for temperature equilibrium, and we will ignore the photosynthetic storage of energy in plants which is very inefficient.

Now, with a greenhouse in place, we assume the average temperature of the interior rises, and that the glass roof reaches a temperature intermediate between the inside and outside air temperatures:

What really changes a lot is the downwelling IR, increasing from the sky value of 350 W/m2 to 450 W/m2, an increase of 100 W/m2. Convective heat generated (but temporarily “trapped”) within the greenhouse increases substantially, from 208 without the roof to 275 with the roof, for an increase of 67, which further heats the air, which in turn is helping to heat up the roof.

But notice that the convective heat loss by the greenhouse roof (200 W/m2, inferred as a residual) is only 8 W/m2 less than if the greenhouse was not there (208 W/m2). In contrast, the extra IR energy “input” (actually, reduced IR “loss”) is twelve times as large (100 W/m2) as the reduction in the convective loss (8 W/m2).

Of course, changing any of the assumed numbers will change the result. But, assuming I haven’t made a fundamental mistake, I think you would find that the “greenhouse effect” will consistently be larger than the convective inhibition effect.

So, maybe the greenhouse effect really does work like a real greenhouse. Again, the basic issue is this: replacing the downwelling sky radiation with a roof that is opaque to infrared (but still transparent to sunlight) represents a huge decrease in the IR energy loss by the vegetation, whereas the greenhouse roof still generates convective heat loss nearly as large as if the greenhouse wasn’t there.

I’m open to ideas, and better estimates of energy fluxes on this subject. The problem is actually surprisingly difficult one to think through. There are many energy fluxes involved (I haven’t even addressed energy losses out the side of the greenhouse) and the trick is to know which are the important ones and which ones can be ignored for the purposes of a rough estimate.

For example, the emissivity of glass is less than 1, but what that means is that it “traps” even more IR energy inside because it partly reflects the higher levels of IR the warmer vegetation is emitting upward.

What do the experts say about all this? I’m sure this problem has been analyzed before, probably in great detail, by multiple aggie graduates in their theses. Unfortunately, a Google search on “greenhouses” and “energy budget” is hopelessly cluttered with pages related to the Earth’s greenhouse effect (wow! how did that happen?)

If anyone is aware of studies done on the energy budget of greenhouses (of the agricultural kind), I would appreciate a reference or two. But until someone finds a serious error in the above analysis, I’d say we might need to admit that the “greenhouse effect” is pretty accurately named.

UPDATE: It appears the debate was brought up in the literature by R. Lee (“The Greenhouse Effect”, J. Appl. Meteorology, 1973) who has been referenced by many as showing a greenhouse does not work through the greenhouse effect, but he curiously admits the analogy “is correct only with respect to the glass, not with respect to the space enclosed”. Well, duh. That’s the point…the glass produces a greenhouse effect. In any event, his paper was refuted by Edwin Berry (Comments on “The Greenhouse Effect”, J. Appl. Meteorology, 1974) who showed several problems with Lee’s analysis.

So, I guess I’m left wondering…where did the oft-cited claim that a greenhouse does not operate through a greenhouse effect come from?

The Version 5.6 global average lower tropospheric temperature (LT) anomaly for July, 2013 is +0.17 deg. C (click for large version):

The global, hemispheric, and tropical LT anomalies from the 30-year (1981-2010) average for the last 19 months are:

YR MON GLOBAL NH SH TROPICS
2012 1 -0.145 -0.088 -0.203 -0.245
2012 2 -0.140 -0.016 -0.263 -0.326
2012 3 +0.033 +0.064 +0.002 -0.238
2012 4 +0.230 +0.346 +0.114 -0.251
2012 5 +0.178 +0.338 +0.018 -0.102
2012 6 +0.244 +0.378 +0.111 -0.016
2012 7 +0.149 +0.263 +0.035 +0.146
2012 8 +0.210 +0.195 +0.225 +0.069
2012 9 +0.369 +0.376 +0.361 +0.174
2012 10 +0.367 +0.326 +0.409 +0.155
2012 11 +0.305 +0.319 +0.292 +0.209
2012 12 +0.229 +0.153 +0.305 +0.199
2013 1 +0.497 +0.512 +0.481 +0.387
2013 2 +0.203 +0.372 +0.034 +0.195
2013 3 +0.200 +0.333 +0.068 +0.243
2013 4 +0.114 +0.128 +0.101 +0.165
2013 5 +0.083 +0.180 -0.015 +0.112
2013 6 +0.295 +0.334 +0.255 +0.219
2013 7 +0.174 +0.134 +0.215 +0.077

Note: In the previous version (v5.5, still provided due to contract with NCDC) the temps are slightly cooler, probably due to the uncorrected diurnal drift of NOAA-18. Recall in v5.6 we include METOP-A and NOAA-19, and since June they are the only two satellites in the v5.6 dataset whereas v5.5 does not include METOP-A and NOAA-19.

New names of popular files:

uahncdc_lt_5.6
uahncdc_mt_5.6
uahncdc_ls_5.6

Last week, I was looking at the North Pole webcam imagery available as a time lapse video here. You can see the formation of meltponds on the ice in the last couple weeks, and then in the last few days the area around the main buoy have turned into a rather continuous, shallow pond.

But if you back up several days, you will see an unusual sight…the bottom of a bird perched on top of the camera structure:

Wildlife at the North Pole is very sparse (probably even more unusual at the South Pole, unless they are having a party at the station there). The ocean there is largely devoid of life, and it is rare that a fox or polar bear wanders there, since there is virtually no food. Check out North Pole on Wikipedia.

Anyway, I just thought it was interesting that it had gotten warm enough there for something living to actually be caught on camera.

Of course, we wouldn’t want too much life to show up there. Might get too crowded. We need to spend billions or trillions of $$ to try to freeze it all back to lifelessness. </sarc>

OK, so yesterday’s hearing really was entitled, “Climate Change: It’s Happening Now”. I like my title better.

In this exceedingly rare photo of me actually cracking a smile, note my subliminal shout out to the “Coke” brothers (whom I’ve never met, btw…I don’t even know what they do):

From the opening remarks made by the Democrats on the Environment and Public Works (EPW) Committee, apparently you can see climate change yourself just by looking in your backyard, or seeing how far from shore fishermen must go now to catch fish, or even (help me with the logic on this one) the fact that smoking causes cancer.

I just submitted my updated written testimony (Spencer_EPW_Written_Testimony_7_18_2013_updated) to include the following chart (Click for full size):

This chart illustrates that, yes, we are currently warm, but not significantly warmer than the Medieval Warm Period (MWP) or the Roman Warm Period (RWP). So how is it we know today’s warmth is human-caused, when the last two warm periods couldn’t have been caused by humans? Hmmm?

And if you want to hit me with a Hockey Stick, might I remind you that there are many more papers supporting the MWP and RWP than there are supporting the Hockey Stick’s slick revision of history?

Or does “consensus” only count when it supports your side?

What’s that you say? The hockey stick is now the “new consensus”? So a scientific consensus can be wrong, after all? Hmmm.

Hearing Post Mortem
The advertised star of the show was Heidi Cullen (aka “de-certify all TV meteorologists who don’t toe the line on global warming Heidi”) who did an admirable job of presenting a litany of half-truths (hurricanes have increased [except in the last 7 years]; strong tornadoes have decreased [but she couldn’t bring her self to actually say that]; wildfire acres burned have increased dramatically [but the number of wildfires have decreased dramatically…all consistent with the USFS “let it burn” policy]; droughts and floods have increased [except NOAA’s charts say there is no change over the last 100 years], etc.).

Roger Pielke, Jr. was absolutely devastating in his testimony. Here’s a guy who claims to largely support the IPCC party line, even claiming increasing CO2 is having a “profound” effect on the climate system, yet he chides those who would try to use severe weather as evidence of climate change. The evidence simply isn’t there. Very Lomborgian, sans the sexy T-shirt.

During my testimony (in the Flash video, starting about 3:04 for my oral, and 3:23 for follow-up questions/interrogation) I decided to depart from my usual practice of reading of a prepared text to just winging it. There is VERY little you can cover in 5 minutes, and there were a number of things I would have liked to have said, but there simply isn’t time…that’s just the way committee hearings go.

All of the senators were moving in an out of the hearing room for a floor vote, so there were only 2-4 senators present at any given time.

Thanks to all of those who have posted and e-mailed supportive comments…I really appreciate it. Getting flogged in public by Sen. Boxer (last time I testified) and Sen. Whitehouse (this time) is not one of my favorite activities. But I warned the staffers I wasn’t going to be pushed around this time without some pushing back. I think we did OK for a hearing where the witness numbers were stacked against us.

I’ve been receiving more e-mails than usual asking about chemtrails, the supposed clandestine spraying of chemicals by jet aircraft, so I thought I would talk a little about the issue.

I was at a townhall meeting a couple years ago, and some biker dude got up and demanded that our congressman do something about chemtrails (the congressman said he had never heard of the issue before). Based upon the level of interest I have seen, there is considerable popular support for the view that chemtrails exist.

First let me say there are such things as “conspiracies”…some people conspire together with all kinds of nefarious motives, both inside and outside government. But not everything that happens in life is a conspiracy.

Jet aircraft at high altitudes produce condensation trails (contrails) which form from water vapor, one by-product of combustion. Some of these clouds can be colorful at sunrise or sunset, just as natural clouds are. Contrail activity has increased dramatically since the 1950s, for the obvious reason that high altitude jet traffic was almost non-existent before that time.

It is indeed possible that the high altitude cirrus clouds formed by jets might have contributed to warming in recent decades due to the greenhouse effect produced by cirrus clouds (thin cirrus reduce outgoing infrared radiation more than they reflect sunlight), although research on this has a large amount of uncertainty.

Now, I suppose it’s possible the Air Force or some other entity has experimented with spraying of chemicals from jets for various purposes. For example, chemical defoliants were sprayed by aircraft from low altitudes during the Vietnam War. But there is no evidence I am aware of that any of the jet contrails you see in the sky on a daily basis is anything other than the passive (and necessary) result of combustion.

Contrails don’t always form behind a jet because sometimes the air is so dry that it absorbs the water vapor from aircraft without condensation taking place. When I was the lead scientist on a microwave radiometer we used to fly over thunderstorms on a modified U2 aircraft, the U2 pilots told us stories of flying spy missions; if the U2 started forming a contrail, they would return home because the aircraft would be too easy to spot from the ground.

I was looking at some of the claimed evidence for chemtrails, for example a 1990 USAF chemistry course outline entitled “Chemtrails”. This indeed seems to establish that the USAF coined the term “chemtrail”, but it was simply a play on “Contrails”, a handbook routinely distributed to cadets. I looked through the chemistry course materials and there was no mention of “chemtrails” in the modern sense of the word.

And graphic artists don’t help when they come up with spoofs, like this one showing airline pilots marching against chemtrails:

Another supposed proof is patents related to spraying of chemicals from aircraft. There is some truth to this claim, because with talk of geoengineering the climate system to offset global warming, there has been considerable interest in spraying a variety of substances into the stratosphere as a way to reflect sunlight in the manner of a large volcanic eruption. As a result, private companies are patenting methods for performing this spraying if it ever becomes a funded project.

But the claim that daily, routine jet traffic involves the secret spraying of chemicals for population control by the government, or to keep us sick to support the pharmaceutical industry, etc., is pretty wild. There is much more information debunking various chemtrail claims at a website called contrailscience.com.

So how do flying saucers fit into this? Well, it was pointed out that a patent for a chemtrail (or any other) device does not mean that a device has ever been developed…or that it would even work. I’d be interested in hearing some physicists’ opinions on the patent for a Space vehicle propelled by the pressure of inflationary vacuum state:

But, I suppose conspiracy is in the eye of the beholder, and I’m sure someone in comments below will claim I am part of the conspiracy that perpetuates the “myth” of the greenhouse effect. Oh, well.

After 10 days in Michigan’s U.P. for my 40th high school reunion, here’s the belated monthly global temperature update.

We added two satellites to the processing, Metop-A starting in 2007 and NOAA-19 starting in 2009. The resulting anomalies, which we will call Version 5.6, differ by as much as 0.04 deg. C from v5.5. You can read the details of the new processing here.

We are now making good progress on Version 6.0, which includes a variety of improvements in our processing procedures which have taken much more time than we anticipated.

The Version 5.6 global average lower tropospheric temperature (LT) anomaly for June, 2013 is +0.30 deg. C (click for large version):

The global, hemispheric, and tropical LT anomalies from the 30-year (1981-2010) average for the last 18 months are:

YR MON GLOBAL NH SH TROPICS
2012 1 -0.145 -0.088 -0.203 -0.245
2012 2 -0.140 -0.016 -0.263 -0.326
2012 3 +0.033 +0.064 +0.002 -0.238
2012 4 +0.230 +0.346 +0.114 -0.251
2012 5 +0.178 +0.338 +0.018 -0.102
2012 6 +0.244 +0.378 +0.111 -0.016
2012 7 +0.149 +0.263 +0.035 +0.146
2012 8 +0.210 +0.195 +0.225 +0.069
2012 9 +0.369 +0.376 +0.361 +0.174
2012 10 +0.367 +0.326 +0.409 +0.155
2012 11 +0.305 +0.319 +0.292 +0.209
2012 12 +0.229 +0.153 +0.305 +0.199
2013 1 +0.497 +0.512 +0.481 +0.387
2013 2 +0.203 +0.372 +0.034 +0.195
2013 3 +0.200 +0.333 +0.068 +0.243
2013 4 +0.114 +0.128 +0.101 +0.165
2013 5 +0.083 +0.180 -0.015 +0.112
2013 6 +0.298 +0.337 +0.259 +0.221

Yesterday I spoke with EnviroMission President Chris Davey to get an update on the progress of the first, large-scale solar tower (aka solar updraft tower, or solar chimney). EnviroMission is progressing through the permitting process and plans to start construction late next year in La Paz County, Arizona.

Billed as a 200 MW electrical generation facility, its towering hot air chimney will be about 2,600 ft tall, making it the second tallest manmade structure in the world, and about twice as high as the Empire State Building.

What has always captured my imagination about the concept is that it uses the daily generation of warm air at the surface by the sun to generate electricity. It takes the familiar principle of a chimney filled with buoyant, hot air to the extreme. The taller and wider the tower, and the hotter the air it contains, the greater the potential for energy generation. The solar heated air in the tower continuously draws air into the 2.5+ mile wide glass/plastic canopy and through approximately 32 wind turbines, each rated at 6.25 MW, circling the base of the tower.

Now, all of this hot air would have been generated anyway, without the solar tower there. But it would have driven turbulently mixed thermals as pockets of buoyant hot air rise and gradually warm the lower troposphere during the daytime. The solar tower simply organizes all of this buoyant energy into a single updraft, which will drive a fairly continuous 30 knot wind through the 32 turbines.

One advantage of this design over conventional solar is since the ground will absorb much of the heat, electricity generation will continue at night as the ground gives up that heat, and the outside ambient air temperature cools by about 30 deg. F, helping to maintain buoyancy in the tower.

Design details are still being optimized by industry leader Arup Engineering, based in the UK. Mr. Davey mentioned a couple of the remaining design uncertainties, such as what material to use for the canopy (tempered glass or some kind of plastic); easy servicing of the clear panels is very important.

The facility requires no water for cooling, a significant advantage, and is designed to last for decades. I forgot to ask about the anticipated effects of wind loading on a tower that tall, but Mr. Davey said there are no major design problems with the facility.

Here’s a pretty cool computer animation video which was made back when the tower height was anticipated to be 1,000 m, rather than 800 m. From what I understand, EnviroMission is also negotiating solar tower projects in Texas, and a few foreign countries, as well.

(Any errors, misrepresentations, or misrememberings in the above are my own.)

Since I’m getting asked to comment on the President’s speech, I guess it’s time for a little detour from science into policy. If you don’t like me mixing science and policy, go complain to Al Gore or Joe Romm or Jim Hansen or Gavin Schmidt or Michael Mann or the American Meteorological Society or the American Geophysical Union or the American Physical Society…or the President himself.

Oh, I could go into the President’s appeal in his address today to those who don’t know any better…that severe weather is supposedly worse due to global warming. Sorry, but by almost all objective measures, severe weather hasn’t gotten worse (storm damage costs increase over time, but that increase isn’t due to weather; Sandy-type storms have always occurred, and always will…they just hardly ever hit a major metropolitan area).

Or, I could go into the silliness of his equating carbon dioxide (which is necessary for life on Earth) to poisonous chemicals like arsenic and mercury.

Or maybe his swipe at skeptics as flat-Earthers, even though most, if not all, of us DO believe that humans influence climate to some extent. (I thought he understood “nuance”?) But all of these things have been addressed by me and others before in considerable detail.

Or his cherry-picking of data. Yes, even our satellite measurements of lower atmospheric temperatures over the U.S. registered record warmth in 2012. But John Christy also tells me our measurements for Australia (similar in size to the U.S.) in 2012 were below normal.

And our tropical tropospheric temperatures (where almost 50% of Earth’s sunlight is absorbed) have a 34-year temperature trend which is not statistically different from zero, in stark contrast to 73 state-of-the-art climate models.

Unfortunately, our President reminds me of a Hollywood star who thinks we can wave a magic wand and create abundant renewable energy if we just try a little harder. A few years ago I debated Daryl Hannah on TV down in Cancun during an IPCC climate conference. I was impressed with her knowledge of the pros and cons of various renewable energy strategies.

But after we were done filming, she told me, basically, “we just need to switch over to wind and solar right now”.

Excuse me? I’m sorry, I guess I was assuming too much regarding this Hollywood actress’s knowledge of basic physics.

It doesn’t matter how badly you want renewable energy to replace fossil fuels and nuclear, there are a few obstacles to overcome, akin to “you can’t get something from nothing”.

Wind, solar, and biomass all have very low energy densities compared to fossil fuels or nuclear, which are very dense concentrations of energy. Generating a substantial (i.e. realistic) amount of renewable energy is VERY expensive in materials and land. How many poor kids you want to take food and medical care from to pay for it?

Plus, for wind and solar, it isn’t always there when you need it (at night, when it’s cloudy, when the wind doesn’t blow). So, it has to be backed up with fossil fuels anyway.

Punishing our most cost effective forms of energy (as the President and the EPA want oh-so-badly to do) just further deepens our economic downturn. If the President really is concerned about “the children” maybe he should examine what really hurts the children – poverty.

Affordable, abundant energy is required to generate wealth, and without wealth, you can’t help those who can’t help themselves. I thought that’s what our President wanted to do..help the poor? But how can we do that if we punish the wealth generators at every turn?

In fact, I can’t imagine a better plan for purposely destroying the economy. Strike it at its heart, the availability of abundant low-cost energy.

Until we come up with affordable and widely deployable renewable energy sources, a war on fossil fuels is a war on the poor. Basic Economics 101. Wealth diverted to wasteful projects (or wealth destroyed) is no longer available for more deserving projects.

Yes, we need to continue renewable energy research, since fossil fuels won’t last forever. But you cannot simply legislate (or as Obama wants to do, regulate, without approval from Congress or the electorate) new forms of energy into existence.

The question is, how do we get from here to there? Now that we are finding global warming is, at worst, progressing at only 50% the rate predicted, we have time to be smart about it (assuming it’s entirely our fault and bad for life on Earth, which I’m not convinced of. Carbon dioxide is just as necessary for life as oxygen, yet it is over 500 times less abundant).

This isn’t a science fiction movie we are living in. I’m afraid the low-information voter won’t “get it” until we have brownouts and blackouts. As more coal-fired power plants are shut down, that day is fast approaching.

Or maybe the economy will be so weak we won’t need all that extra energy anyway.

A polar bear which collapsed from heat exhaustion before it could be shot.

I have in my possession a copy of one of the most authoritative books ever written on Arctic sea ice, including a section on the warming of the Arctic. It is written by one of the pioneering researchers in Arctic sea ice, N.N Zubov, a Russian, who spent his career studying the Arctic region.

His observations of warming in the Arctic, which he described as not localized, but universal, are taken from his book entitled Arctic Ice. I have excerpted several pertinent passages, which I’m sure will convince you that warming of the Arctic can scarcely be denied:

Along with the fluctuations in ice abundance in each individual sea from year to year, in late years a most interesting phenomenon has been observed – a warming of the Arctic, as evidence by a gradual and universal decrease in ice abundance. The main evidence of this general warming of the Arctic are:

Still more remarkable is the fact that the warming of the Arctic is not confined to any particular region.

I find these observations to be quite compelling evidence that warming of the Arctic is indeed unprecedented. Who would dare deny it? Clearly, we must do something about our carbon dioxide emissions!!

NOTE: Oh, silly me. This book was written in the late 1930’s. Nevermind.