Chemical Engineer Takes on Global Warming

As my two regular readers will know, I have lately become a regular reader and infrequent commenter on WattsUpWithThat.com, a blog mostly dedicated to searching out the veracity of claims that man's activities are the cause of global warming.

I am also one who has a BS in chemical engineering, and therefore follow the doings in that rather esoteric world. That reminds me of a true story that happened to your blogger, in my senior year of undergraduate engineering school. It was a fine Spring day in Austin, and a rather cute and shapely co-ed walked with me to class. She asked what was my major, and I told her. She then asked what does a chemical engineer do? So I explained briefly that we design and operate chemical plants. She thought about that for a bit, then asked me, "What kind of leaves do those chemical plants have?" Honestly, she did, and she was serious! It was a fine moment, and I believe I answered her by describing refineries and chemical manufacturing facilities.

Back to the global warming and engineers: I receive my e-copy of Hydrocarbon Processing magazine each month, and in the January 2009 edition was pleased to see that Dr. Pierre R. Latour had written a letter to the editor. Dr. Latour (more on him in a moment) had replied to another fellow on the subject of controlling CO2 in the atmosphere as a means of stopping global warming. Dr. Latour gave several reasons why it is impossible to control the global temperature by changing the amount of CO2 in the atmosphere.

Below is a brief bio of Dr. Pierre Latour, excerpted from an article found here.

Pierre R. Latour is “a recognized authority in process automation technology and successful entrepreneur in several process control ventures. Latour began his career in the early 1960s with DuPont and Shell Oil after receiving a PhD in Chemical Engineering at Purdue.

He worked on the first Shell computer control project (FCC–Deer Park Refinery 1966). A two-year tour as a captain in the U.S. Army followed at NASA’s Manned Space Flight Center managing the Apollo Docking Simulator development.

After mustering out, Latour co-founded Biles & Associates (later acquired by Invensys) and Setpoint (later acquired by Aspen Technology). Latour served in a business development capacity as Vice President at Aspen prior to launching his current consultancy–CLIFFTENT, Inc.”

Dr. Latour, world-renowned PhD and professional licensed chemical engineer, offered this scathing analysis of the entire matter. To see his letter, scroll down to "Author's Reply."

A brief excerpt from Dr. Latour's letter follows. He writes that "Mr. Temple's (the writer of the other letter to editor),counter-claim against my comment about measurable, observable, controllable, stable and robust characteristics of the dynamic, multivariable nonlinear atmospheric temperature control system under design by Kyoto Protocols misunderstands my meaning. These mathematical concepts are part of the foundation of control systems engineering18 recorded in AIChE Journal, ACS I&EC Journal, IEEE Transactions, ASME Transactions and annual JACC conferences since 1960. They provide exact necessary and sufficient conditions for these characteristics for all linear systems and some nonlinear systems. I employed some of these for the Apollo command and lunar modules roll-pitch-yaw digital autopilots and lunar rendezvous trajectory designs11 when I was simulation branch manager, GS-14, Manned Spacecraft Center, NASA, Houston, in 1968 (I was 29 and James E. Hansen19 was 28). This was when President John F. Kennedy charged competent control engineers rather than lawyers to design national control systems. All competent refinery control system engineers and thermostat closers should assure themselves these criteria are met before embarking on designing, implementing and closing feedback control systems. Not to mention assessing the possible performance, merit and value of such systems. I did this when I closed one of the first computer loops on a commercial oil refinery fluid catalytic cracker regenerator temperature in 1967, aware of the consequences if the regenerator catalyst slide valve pressure drop approached zero. Now I am merely trying to acquaint climate change scientists, physicists, lawyers and politicians promoting such things as Kyoto Protocols that chemical process control system engineering has a useful voice, weak as it is, in climate control engineering." [emphasis my addition - RESowell]

Dr. Latour goes on to write: "The tenuous link between CO2 greenhouse effects and the Earth's temperature indicates humanity has no effective manipulated variable to control temperature; the steady-state gain dT/dCO2 is almost zero. If so, the system is uncontrollable. Kyoto will fail no matter what the political consensus may be."

As it may be that some readers might have some misunderstanding of Dr. Latour's statements, I will attempt here to translate these into more every-day language. First, the required characteristics of variables in a successful control system are what Dr. Latour refers to as "measurable, observable, controllable, stable and robust."

First, some basic control issues should be explained, and I will. A control system is necessary, and indeed these exist all around us, to maintain some quality at a desired point. One everyday example is the temperature dial on the kitchen oven. On mine, one turns a dial from OFF to BAKE position, then turns another dial until the mark is opposite to the desired temperature. When I want to roast a chicken, I set the dial to 325 degrees. The dial adjusts the setpoint in the oven to 325. There is a controller in my electric oven, connected to a temperature sensor at one end, and to an off-on switch that allows electric power to flow through the heating element. When the temperature sensor shows a temperature less than 325, the switch is automatically set to ON and power flows, heating up the heating element, and increasing the oven's temperature. When the temperature sensor shows the oven is at 325, the switch is automatically set to OFF, and the oven begins to slowly cool. When the temperature in the oven drops to about 320, the switch automatically sets to ON again, and the cycle repeats.

In control terminology, the controlled variable is the temperature inside the oven. The manipulated variable is the power flow into the heating element. And here is the key to Dr. Latour's argument: There must be a direct relationship between a change in the manipulated variable (power to the heating element) and the controlled variable (temperature in the oven). In this case, there is, as more power to the heating element results in a greater temperature. An example of no relationship would be when I light a candle in the next room, say the living room. Then, I watch the temperature in the oven, but that does not change. I can blow out the candle, and the oven still does not change. Or, I can turn on the oven, adjust the dial to 325, and light the candle in the living room. As the oven warms up, I can claim that the candle is heating the oven! But, when the candle burns out or is snuffed out, the oven still heats and seems not to be affected by the candle.

Back to Dr. Latour's first requirement: measurable. Measurable means that whatever we are to control, we must be able to somehow measure that, so we know where we started, where we are at any point in time, and when we have reached our desired goal. If we cannot measure it, we cannot control it. This is a fundamental requirement of control theory and is not subject to debate. Period. It does not matter how many Nobel prizes one has, or PhD's in any number of subjects, that point is not open to debate, consensus, or argument. Dr. Latour makes the point that nobody knows the temperature of the globe, as it cannot be measured due to the large size of the globe. It can only be estimated, and that estimation procedure is inaccurate.

Next, observable. This is closely related to measureable. One must be able to observe the variable, typically by measurement or by some other means such as inference.

Next, controllable. Controllable means that a change in the manipulated variable has an observable, measurable, and consistent effect on the control variable. Stated another way, and using the kitchen oven as the example, when the power flows to the heating element, the oven temperature increases. Not only does it increase, it always increases, each and every time. This is one point on which CO2 fails as a means to control global temperature. Dr. Latour refers to the dT/dCO2 is almost zero. This simply means that the amount of change in CO2 (dCO2) produces some amount of change in global temperature (dT). For the change in temperature over time, during the recent warming period, Dr. Latour wrote: "To quantify the chemical engineering perspective situation, the data for 1975 to 1998, show a barely perceptible rise of 0.6°C/33 years = 0.0182°C/yr before it stabilized from 1998–2008."

Next, stable. Stable means that the variables do not change over time, that is, the amount of temperature rise in the oven is the same each time one turns on the oven. Stated another way, it takes the oven the same amount of time to reach the desired temperature. It would be difficult to control if the oven heated up in only 10 minutes one time, but took an hour the next time. Or, using the gas pedal in a car as the example, one expects the car to respond in the same fashion with a certain amount of foot pressure on the gas pedal.

Finally, robust. This means that the control system will perform satisfactorily even when the actual system does not perfectly match the control design.

Putting this all together, one can easily see that CO2 in the atmosphere is not the way to control global temperature. What one can also see from the CO2 estimations and temperature estimations throughout history is that CO2 remained relatively stable, while global temperatures went up during the Roman Warming, the Medieval Warming, and decreased dramatically during the Little Ice Age. More recently, while CO2 perhaps was fairly constant or even rising a bit due to industrial activity, the globe warmed from 1900 to 1940, then cooled from 1940 to 1970. Clearly, CO2 is not a good control variable because it does not seem to matter what the CO2 level is, as temperatures go up, and go down.

This last point was made in an even more compelling manner by Frank Lansner in a guest post on WattsUpWithThat.com. Mr. Lansner shows that the Antarctic ice core data shows temperature rising, and temperature falling, at the same level of CO2 in the atmosphere. This happened consistently over four consecutive ice ages and inter-glacial warm periods. From basic control theory, this could not happen if CO2 were a control variable for global temperature.

This has gotten rather long, but I believe the point is made. The global warming scientists have some more thinking to do, and they really should consult with the experts in controls: the chemical engineers.

UPDATE 1, (November 3, 2009) Dr. Latour and Mr. Temple had another exchange of letters on the control aspects of CO2 and global warming, in the February 2009 issue of Hydrocarbon Processing, which may be found here.

UPDATE 2, (December 4, 2009) This post is the number one most visited posting on SLB, per my recently-installed tracking software. This post receives approximately 7 percent of all visits. Please, continue to spread the word.

UPDATE 3, (March 15, 2010) Dr. Latour has another article, this one an editorial in Hydrocarbon Processing, February 2010, on CO2 and Earth's temperature. I wrote on this here, with a link to his HP editorial here. This post (Chemical Engineer Takes on Global Warming) now receives approximately 10 percent of all visits to SLB.

Roger E. Sowell, Esq.