Archive for July, 2016

The Warm Earth: Greenhouse Effect, or Atmospheric Pressure?

Saturday, July 30th, 2016

I continue to see some commenters here supporting the notion that the warmth of the lower atmosphere and the Earth’s surface can be explained through atmospheric pressure, rather than the so-called “greenhouse effect” (GE). The GE comes from the ability of greenhouse gases in the atmosphere to absorb (gain) and emit (lose) infrared radiation at terrestrial temperatures.

Of course, if there is no GE, then global warming cannot be caused by the addition of more greenhouse gases to the atmosphere. This view has a pretty widespread following, and I continue to get emails asking me about it.

I consider the “no such thing as a greenhouse effect” people to be wrong, and once again I will try to explain the reasons why. The GE does not contradict the 2nd Law of Thermodynamics, and without the GE, we would not even have weather in the atmosphere (more on that, below). I have written many posts covering this subject over the years, but since the issue persists, I will go over the high points once again.


The first thing we have to agree upon is what causes the temperature (of anything) to change: energy gain and energy loss. It doesn’t matter whether we are talking about air, the human body, a car engine, or a pot on the stove…temperature goes up when energy gain exceeds energy loss, and temperature goes down when energy loss exceeds energy gain. This is basic thermodynamics, it is how quantitative temperature changes are estimated when engineers design stuff, in weather forecast models, and in physics calculations in general. If we cannot agree on this basic point there is no reason to continue the discussion.


The reason why we must talk in terms of an ‘energy budget’ when discussing temperature is that people tend to forget that energy LOSS is just as important as energy GAIN. For example, you cannot compute what the temperature of an object will be by shining sunlight of a known intensity on it. Yes, sunlight is virtually the only source of energy in the climate system, but the average surface temperature of the Earth cannot be estimated from the strength of this source; the processes which control the rate of energy LOSS are also involved. And the Earth’s greenhouse effect reduces the rate of energy loss by the Earth’s surface and lower atmosphere.


First, let’s examine the effect of air pressure. It is true that if you take an air parcel at low pressure (say, high in the atmosphere) and bring it down to the surface it will be compressed and its temperature will go up. If no heat is gained or lost to its surroundings (an adiabatic process, and we will ignore the complicating effects of water vapor condensing) the rate of temperature rise is about 9.8 deg. C per kilometer in altitude, the so-called ‘adiabatic lapse rate’.

So, if the atmosphere was continually mixed, and we ignore the effects of water evaporation and condensation, then the atmosphere would be warmer near the surface than at high altitudes, and the temperature would fall off with height at the rate of about 9.8 deg. C/km. This is the basis for the argument that it’s not the greenhouse effect that warms the Earth surface so much (and Venus’ surface dramatically more), but atmospheric pressure, instead.

But this incomplete view has a number of unexplained problems…

For example, what would the absolute temperatures be? The adiabatic lapse rate only tells you how temperature changes with height…not what the actual temperature would be. So, what temperature would you start the parcel of air high in the atmosphere at, before bringing it to the surface and warming it? Why did you choose that initial temperature? Existing theory, with the greenhouse effect, can allow you to compute that temperature from first principles.

And how to explain the effect of convective heat transfer from the Earth’s surface to the atmosphere, if the atmosphere has no way to cool itself? I think that the no-GE folks agree that there is net convective heat transfer from the surface of the earth up into the atmosphere (that’s mostly how the atmosphere get heated, by the surface). As part of this, water is also evaporated at the surface which requires energy…this energy is then released high in the atmosphere when the vapor condenses into clouds and precipitation, contributing to the convective heat transfer.

If this convective heating of the atmosphere is continuously occurring, what prevents the atmosphere from warming endlessly? It must have some mechanism of heat loss just as large as the heat gain in order for the temperature to finally settle out around some average value. The answer is that the atmosphere continuously cools by emission of infrared radiation to outer space, primarily by ‘greenhouse gases’ in the atmosphere, water vapor being the most important, and carbon dioxide being second most important.

But that IR emission occurs in all directions…not just upward. And it’s the downward emission of IR radiation that causes the greenhouse effect.


Anything that emits IR also absorbs IR, and this makes the intuitive understanding of how IR radiation affects the atmospheric temperature profile difficult. Unlike the sun, which is a single (and ultimate) source of energy, every atmospheric layer is both an emitter and absorber of IR energy. The fact we can’t see IR radiation with our eyes further impedes our intuition.

Importantly, the amount of IR energy a parcel of air absorbs is mostly independent of temperature, but the amount it emits is very dependent on temperature. The idea that air emits IR at the same rate it absorbs is, in general, just plain incorrect.

The atmosphere, even though it is colder than the surface of the Earth, emits IR toward the surface. This does not violate the 2nd Law of Thermodynamics, which only says that the NET flow of energy must be from higher temperature to lower temperature.

EXAMPLE: Think of two identical, solid plates at the same temperature facing each other. Hopefully we can all agree that there will be no net flow of IR energy between them, because they are both emitting IR at the same intensity.

Now imagine one plate is 10 deg. C cooler than the other…there will be a net flow of IR radiation from the warmer plate to the cooler plate, right?

But what if the cooler plate is 200 deg. C cooler than the warm plate, rather than only 10 deg. C cooler? Can we agree that the net flow of IR radiation will be even larger? If so, that means that the IR radiation from the cool plate to the warm plate affects the net flow of IR energy between the two plates, right? So, the colder object does effect the energy budget (and thus temperature) of the warmer object…because energy LOSS is just as important as energy gain when determining temperature.

If you want to (curiously) argue that the cold plate doesn’t actually emit energy that is absorbed by the warmer plate (as PhD physicist Claes Johnson has argued with me), you still must admit that the temperature of the cold plate DOES affect the net rate of IR transfer from the warmer surface to the colder surface, right? Well, that’s all that is required for the existence of the greenhouse effect.

And that’s what happens with the atmosphere…downward IR radiation from the sky reduces the net IR loss by the Earth’s surface, causing it to achieve a higher temperature than it would have if there was no downward radiation from the sky, and the Earth’s surface was allowed to emit IR unimpeded to the cold depths of outer space (2.7 K temperature). It doesn’t matter that the atmosphere is colder than the surface.

How do we know there is downward IR radiation from the sky?

Because it can be measured. Instruments that are selectively sensitive to IR measure changes in temperature within the instrument in response to changes in the balance between incoming and outgoing IR radiation. You can buy a handheld IR thermometer, which is sensitive to a range of IR wavelengths that are only somewhat affected by water vapor and CO2, point it directly upward at a clear sky, and it will register a fairly cold temperature. By itself, this doesn’t prove much. But if you then point it at an oblique angle (say 45 deg), it will register a warmer temperature.

Now, think about what just happened… even though you are pointed the IR thermometer at a cold target, its temperature actually went up! So, cold objects can actually make warm objects even warmer still! (If that cold object is warmer that an even colder object it replaces…like the atmosphere at a cold temperature instead of outer space near absolute zero temperature).

This is the most direct proof of the greenhouse effect I can think of. After all, what is the greenhouse effect? It is downward IR radiation from the sky causing the surface temperature to increase, compared to if that downward radiation didn’t exist. That’s exactly what happens within the handheld IR thermometer, and it is going on everywhere on Earth, all the time.


One of the features of a greenhouse atmosphere, which many people don’t realize, is that in addition to the lower atmosphere being warmer, the upper atmosphere is colder than it would otherwise be without the greenhouse gases. For example, addition of CO2 to the atmosphere is supposed to warm the surface, but cool the stratosphere and mesosphere. Greenhouse gases destabilize the atmosphere to the point that convection occurs, which then pushes the lapse rate toward a convective one (between dry adiabatic and moist adiabatic). This was first demonstrated with radiative transfer calculations by Manabe and Strickler (1964).

So, it is actually the destabilization of the atmosphere (net radiative warming below, net cooling aloft) by the greenhouse effect that leads to convection, clouds, and precipitation. If the atmosphere could not absorb or emit IR energy at all (a physical impossibility), and if we ignore sunlight absorption by ozone and water vapor, the atmosphere would become the same temperature as the Earth’s surface through direct conduction. This would take a very long period of time to occur, because air is such a good thermal insulator (which is why Styrofoam works so well). This kind of atmosphere is very stable, convectively, and vertical motions would largely cease (there might be some small planetary-scale motions due to the poles being cooler than the tropics.


The quasi-adiabatic lapse rate observed in the atmosphere is the result of convective overturning, which itself is caused by destabilization of the atmosphere by the greenhouse effect. The lapse rate, by itself, cannot explain why the surface temperature of the Earth is what it is…it only tells us how the temperature changes with height in response to convective overturning….not what the temperature would be.

The atmospheric greenhouse effect involves radiative fluxes of hundreds of Watts per sq meter, and is included in all of the weather forecast models that are used around the world every day to forecast weather. Without the GE, the models would simply not work; you cannot ignore infrared radiative transfer in the atmosphere. Without downwelling IR radiation from the sky, nighttime on Earth would be much colder than is observed, as 300+ W/m2 of continuous cooling to outer space would cause rapid temperature drops.

Those IR effects are the basis for atmospheric temperature sounding from IR radiometers, flying since the 1980s with the HIRS instruments. The technology simply would not work if CO2 in the atmosphere was no emitting IR radiation upward and downward. The latest NASA AIRS instrument has actually measured the decrease in IR energy from the Earth as CO2 in the atmosphere has increased. This is observational evidence that an increased greenhouse effect reduces the rate of loss of IR energy to outer space, which should lead to some warming.

WFG13-11452016212The IR emission by water vapor, which obscures the satellites view of the surface, can be seen in this GOES 6.7 micron image from this morning. That IR emission is occurring downward as well as upward, contributing to the greenhouse effect.

The fact that you can see the direct effects of the atmospheric greenhouse effect with even a $50 handheld IR thermometer provides further evidence that the greenhouse effect exists.

A few of the comments which will follow this post will no doubt argue against what I just presented. Fancy, technical buzzwords will be thrown around to convince you why I’m wrong. Australian Doug Cotton (who sometimes posts comments under fake names) is the leading proponent of this view. Yes, I agree with Doug that if you take a parcel of at at a certain temperature and compress it (increase its pressure), its temperature will rise…but this comes nowhere near to quantitatively explaining why the Earth’s surface temperature (or upper atmospheric temperature) is what it is.

Let me just say that, the concepts I have outlined above have been used to predict what the average temperature profile of the atmosphere looks like, from first principles and based upon laboratory measurements of the IR absorption by various gases, and they work very well (we have done this ourselves). You can run a time-dependent 1D model with an assumed atmosphere near absolute zero, or even at 1,000 deg. C, and the physics in the model (involving physcially-based energy gain and energy loss terms in every atmospheric layer) will gradually produce an average temperature profile that looks very much like that observed in the real atmosphere.

Until the no-greenhouse effect people can do the same, their hand waving arguments will be only that: hand waving arguments. And even if they could do it, how would they justify ignoring infrared radiative transfer effects in the atmosphere, which have been so well established for many years?

Finally, just because the greenhouse effect exists does not mean that global warming in response to increasing carbon dioxide will be a serious problem…that is another issue entirely, and involves things like cloud feedbacks. I’m only referring to the existence of the Earth’s natural greenhouse effect, which to me is largely settled science.

If you are interested in my many other posts on other aspects of the greenhouse effect, just enter that search term into the search box near the top of the sidebar panel to the right.

Pokemon Nerds View Chinese Spy Satellite Rocket Burning Up Over Western U.S.

Thursday, July 28th, 2016

Thousands of lucky onlookers got to see the upper stage of a Chinese rocket reenter the atmosphere and burn up over the western U.S. late last night. This nice video of the event was taken by Matt Holt over the Utah Valley, surrounded by excited “Pokemon nerds” (in Matt’s words).

The debris was the upper stage of Long March 4B rocket launched a month ago from the Gobi Desert, carrying an electronic surveillance spy satellite:

A Long March 4B rocket launched June 26, 2016 carrying China's second Shijian 16 electronic surveillance satellite. Credit: Xinhua

A Long March 4B rocket launched June 26, 2016 carrying China’s second Shijian 16 electronic surveillance satellite. Credit: Xinhua

The rocket upper stage reentered about 12 hrs earlier than expected from orbital debris predictions made by The Aerospace Corporation, which provided this morning’s updated calculation of the reentry path, and the ring of visibility (given clear skies):

Solar Impulse: Poster Child for the Impracticality of Solar Power

Tuesday, July 26th, 2016

Solar energy has some legitimate uses in isolated cases, such as providing electricity where there is no other source available, and when you need it so badly you are willing to pay a premium, say, for use on your sailboat.

But the inherent physics limitation to solar energy is that it is so diffuse (so little solar energy falls on each square meter of ground), the efficiency of conversion to electricity is so low (typically 15% or so), and it is so expensive to convert it to electricity with photovoltaic cells (the manufacture of which is expensive and environmentally damaging), that it might never supply more than a small fraction of global energy needs.

Maybe in a few hundred years fossil fuels will become so scarce and expensive to extract that things will change — assuming no forms of nuclear power are ever embraced again. But for now, solar energy can only be kept alive through forcing the public to pay a large premium for it (subsidies). (Those who claim Big Oil is also subsidized need to look into the numbers…government taxes on petroleum far exceed oil company profits and subsidies, while solar powered electricity costs society about 30 times more than gas-fired electricity).

So, what could better illustrate the huge cost and inefficiency of solar energy than to pay a small army of people to build and fly a single-person solar-powered glider around the world in only 16 months?

Now that Solar Impulse has accomplished that $177 million task, renewable energy advocates are rejoicing. But even the people behind the project aren’t saying that we will ever have solar-powered air transport systems.

According to project initiator and Swiss adventurer Bertrand Piccard, who also piloted Solar Impulse for the final leg of the flight,

“Solar Impulse was not built to carry passengers, but to carry messages. We want to demonstrate the importance of the pioneering spirit, to encourage people to question what they’ve always taken for granted. The world needs to find new ways of improving the quality of human life. Clean technologies and renewable forms of energy are part of the solution.”

Now, I’m not against people who have a lot extra money spending it on such adventurous projects. What bothers me is the large number of people who believe it somehow validates a goal of solar-powered transportation systems. I’d wager that much less money (and fossil-fueled support) went into the recent completion of a round-the-world balloon flight in only 11 days…not 16 months.

pig-flyingUntil someone repeals the laws of physics, solar energy will remain a minor player in meeting global energy demand.

While the Solar Impulse project is a remarkable achivement in human ingenuity, it has little more practical significance than building a flight system that will finally achieve the goal of making pigs fly.

Record Warm 2016? What a Difference One Month Makes

Friday, July 1st, 2016

With the rapid cooling now occurring in the global average tropospheric temperature, my previous prediction of a record warm year in the satellite data for 2016 looks…well…premature.

Here’s an update of what the average temperature trend would have to be in the next 6 months for 2016 to tie 1998 as record warmest year in the 38 year satellite record:


Basically, as long as the anomalies stay below the June value of 0.34 deg. C, 2016 won’t be a record warm year.

If only I had kept my mouth shut nine days ago….

UAH Global Temperature Update for June 2016: +0.34 deg. C

Friday, July 1st, 2016

Second largest 2-month drop in global average satellite temperatures.
Largest 2-month drop in tropical average satellite temperatures.

NOTE: This is the fifteenth monthly update with our new Version 6.0 dataset. Differences versus the old Version 5.6 dataset are discussed here. Note we are now at “beta5” for Version 6, and the paper describing the methodology is still in peer review.

The Version 6.0 global average lower tropospheric temperature (LT) anomaly for June, 2016 is +0.34 deg. C, down 0.21 deg. C from the May value of +0.55 deg. C (click for full size version):


This gives a 2-month temperature fall of -0.37 deg. C, which is the second largest in the 37+ year satellite record…the largest was -0.43 deg. C in Feb. 1988.

In the tropics, there was a record fast 2-month cooling of -0.56 deg. C, just edging out -0.55 deg. C in June 1998 (also an El Nino weakening year).

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

2015 01 +0.30 +0.44 +0.15 +0.13
2015 02 +0.19 +0.34 +0.04 -0.07
2015 03 +0.18 +0.28 +0.07 +0.04
2015 04 +0.09 +0.19 -0.01 +0.08
2015 05 +0.27 +0.34 +0.20 +0.27
2015 06 +0.31 +0.38 +0.25 +0.46
2015 07 +0.16 +0.29 +0.03 +0.48
2015 08 +0.25 +0.20 +0.30 +0.53
2015 09 +0.23 +0.30 +0.16 +0.55
2015 10 +0.41 +0.63 +0.20 +0.53
2015 11 +0.33 +0.44 +0.22 +0.52
2015 12 +0.45 +0.53 +0.37 +0.61
2016 01 +0.54 +0.69 +0.39 +0.84
2016 02 +0.83 +1.17 +0.50 +0.99
2016 03 +0.73 +0.94 +0.52 +1.09
2016 04 +0.71 +0.85 +0.58 +0.94
2016 05 +0.55 +0.65 +0.44 +0.72
2016 06 +0.34 +0.51 +0.17 +0.38

The rapid cooling is from the weakening El Nino and approaching La Nina conditions by mid-summer or early fall.

As promised just over a week ago, here’s how we are now progressing toward a record warm year in the satellite data:
The June anomaly is well below the dashed red line which represents the average cooling rate required for the rest of 2016 to tie 1998 as the warmest year in the satellite record. So far my prediction that 2016 will end up being a new record warm year is not shaping up too well…the cooling we are seeing in the troposphere really is spectacular. Just remember, the temperature anomaly can also temporarily rebound for a month, as it did in late 1998.

The “official” UAH global image for June, 2016 should be available in the next several days here.

The new Version 6 files (use the ones labeled “beta5”) should be updated soon, and are located here:

Lower Troposphere:
Lower Stratosphere:

More on the Global Climate Emergency: Email from a “Fan”

Friday, July 1st, 2016

hate_mailI get some hate email from time to time. Actually, not very much. I guess I’m still cruising under the radar.

In response to my post yesterday criticizing Paul Beckwith’s post about the allegedly unprecedented crossing of the equator by jet stream winds (a post which, after much criticism, he has since modified), I received a heartfelt email (reproduced below) asking me to, ummm, back off on my criticism.

This email I received yesterday is rather disturbing because I fear it reveals the low caliber of scientific knowledge that exists out there. Too many people are too easily fooled by pseudo-scientific ramblings which can go viral and cross the globe in a matter of hours. This cuts both ways in the global warming debate, as frequent readers of my blog know I have banned people on my side of the argument for pushing too hard on what I consider to be bad science (e.g. the claim that there is no such thing as the “greenhouse effect”).

Even Jason Samenow from the Capital Weather Gang posted agreement with me that there is nothing unusual about winds at the jet stream level moving back and forth across the equator. Jason also quotes other PhD-level atmospheric scientists in that article.

So, I’m just going to leave this here…I was tempted to answer many of the points made below, but I think it will be more enjoyable for regulars here to take a shot at it.

What A way to treat a fellow scientist. Who the f**k cares if its man made or not! Paul is getting the word out there to people…what are you doing? I don’t see you doing anything except having a web site that no one even knows about…I’ve never heard of you. Paul Beckwith puts a lot of hard work and time into trying to raise the issue…You however are a disgrace to global scientists! Or do you not agree this is an emergency? This one video finally caught some attention and you have to f**k it up…Idiot! We NEED for this to be news so maybe, just maybe something will be done! This video has gone viral…let it be! You have made up lies about him and tried to discredit him…why would you do that??? Many people have moved to the southern hemisphere to get away from the radiation…because this was NOT supposed to happen. You need to take down what you said from your web site! What is happening is dangerous and people need to know…too many people already do not believe GW is real…they need to prepare! They need to know! Jesus Dude…What’s wrong with you? And let’s not throw stones about Donations…You have your own Donation button!!!! Fix it Please…