Comment on Kevin Trenberth’s interview on February 17 2014 – An Example of Misrepresenting Climate Science

Guest essay By Roger A. Pielke Sr.

My son and Kevin Trenberth did an interview for Colorado Public Radio on February 17th. The entire interview is worth listening to, but here I want to comment on a specific statement that Kevin made that is scientifically inaccurate.

The entire interview (well worth listening too) is titled

Is climate change causing extreme weather? Experts disagree – click the listen button at for the interview

In the discussion on added heat during droughts that is due to the increase of atmospheric CO2, Kevin Trenberth said

“You can add up how much of that heat there is and over a six month period it’s equivalent to running a very small microwave over every square foot at full power for about ½ hour”.

The interviewer [Ryan Warner] seemed to be impressed by this analog. The analog of a microwave is an effective image, but it is scientifically wrong for several reasons. Public Radio listeners and Mr. Warner were misled by this analog.

· First, the reduction of long wave radiation emitted to Space due to the added CO2 occurs over the six month time period, not in a short duration burst. Clearly, a short ½ burst of such heat would have a very different effect than when this heat is distributed across a six month time period.

· Second, the effect of long wave radiative flux divergence on surface temperatures from added CO2 (or other greenhouse gas including water vapor) is much larger at night. This is because during daylight, most of the time, vertical turbulent mixing dominates. The atmospheric boundary layer is typically much deeper during the daytime, so that added heat from the increase of CO2 is distributed through a much deeper depth. While the effect on nighttime minimum temperatures can be significant as we showed in our paper

McNider, R.T., G.J. Steeneveld, B. Holtslag, R. Pielke Sr, S. Mackaro, A. Pour Biazar, J.T. Walters, U.S. Nair, and J.R. Christy, 2012: Response and sensitivity of the nocturnal boundary layer over land to added longwave radiative forcing. J. Geophys. Res., 117, D14106, doi:10.1029/2012JD017578. Copyright (2012) American Geophysical Union.

the effect on daytime maximum temperatures (and thus on increasing the heat stress in a drought) will be much less. Kevin did not properly inform the audience how the added heat would be processed differently during the day and night.

· Third, we examined this issue for a seasonal time scale in our paper

Eastman, J.L., M.B. Coughenour, and R.A. Pielke, 2001: The effects of CO2 and landscape change using a coupled plant and meteorological model. Global Change Biology, 7, 797-815

We concluded based on our model sensitivity runs that the radiative forcing effect of doubled atmospheric concentrations of CO2 on regional temperatures over a growing season are minimal (e.g. see Tables 8 and 9). This is especially true for daytime temperatures. Indeed, the biogeochemical effect on the regional weather from added CO2[which Kevin did not mention] was a much larger effect, as was land use change.

The ½ hour of added heat from the microwave forcing that Kevin presented, when properly input over the entire growing season would only result in a trivial effect on maximum temperature (ie. The hottest part of the day)!

Thus, while added CO2 and other human and natural climate forcings certainly can have an effect on large scale circulation features which could exacerbate droughts and fires, the analogy to a microwave that Kevin presented to convince the audience regarding the importance of added surface heating from the radiative effect of the increase of atmospheric CO2 is scientifically incorrect.

Indeed, when we perform model sensitivity experiments, we find that biogeochemical effect of added CO2 on plants (and the feedback to weather) and of land use change are much larger effects on this time and spatial scale.


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Pamela Gray

So basically, in spite of a poor analogy, all this is supposed to show up at night, and a bit during the day, and in large scale weather patterns. Sorry. I just don’t see it. And I don’t buy it. It seems to me that the two of them are arguing over the size of the cooties on a gnat’s head.

Mike Tremblay

When you start involving radiative forcing in this particular situation you have to include all of the GHGs in the atmosphere not just CO2. This is one of the major failings in this example because Water Vapour, which is the dominant GHG, will be much reduced in drought conditions so the radiative forcing from H2O(g) will be significantly reduced compared to any increase that CO2 would cause, effectively allowing more IR to escape to space through the atmosphere.
Not only that, but water in the soil will contribute to a change in albedo and the heat capacity of the soil, leading to a faster change in temperatures at the surface – this, and the contribution of water vapour in the atmosphere, are the main contributing factors to why deserts have such a variation between night and day temperatures.


This microwave analogy reminds me of the “global warming equivalent to 400,000 Hiroshima atomic bombs every day on the planet” meme…


Oh, I thought it was hiding in the deep ocean.

HGW xx/7

I read this article and hear, for the fifteen-millionth time in as many days, about how I am killing the Earth simply by living. Our children are having this drilled into their heads. Every billboard I see, every [self-snip] bumper sticker in Seattle, every exterminating company I come across screams GREEEEEEN!!! I don’t even want to watch the news because I know the establishment will weave it into a story about fast food nutrition if they have to!
…and then I come across this quote in an article on Yahoo: “Don’t blame nature and drought. Human beings, not climate change, are responsible for this situation.”
Do you know which notable authority said that? A wise university professor? Perhaps a hungry, innovative politician? Or maybe one of our prophetic climate scientists, just ready to share that maybe the world isn’t coming to an end?
Nope. The new President of Iran said this about a dying lake in his country. The new leader — of a nation (for lack of a more realistic term) that is a sworn enemy to everything we hold dear — says something that many of our neighbors would label as plasphemy. They are words worth losing your job over and being labeled as a pariah for, according to the UK Green Party.
The President of Iran. Let that sink in.
I am going to go weep in my room. Good night.


Stick with the stuff that matters – land use and weather event mitigation choices. Talking about the disputed effect of trace gases in a free flowing atmosphere is arguing about the insignificant with regard to the pointless.


There is little point to an analogy such as this one. Suppose one DID run a microwave oven for half an hour on every square foot of the planet. Is there anyone who thinks that any of that additional heat would still be around in, say, six months? Exponential decay back to the running not-exactly equilibrium is the only thing that would be observed, with a time constant of at most hours.
The only point of the analogy is to convince scientifically illiterate people of something political, not scientific, quite aside from any errors in the science.
Then there is the far more cogent point that the claimed effect is not, in fact, at all like a microwave running for half an hour. My microwave is 1250 watts. A half hour is 1800 seconds. 1250 times 1800 = 2.25 x 10^6 joules. The number of seconds in a half a year is 15 x 10^6. This is the equivalent of 0.15 Watts per square foot.
So let’s make an analogy that is both more accurate and less threatening. An ordinary flashlight typically draws somewhere in the range of 1-2 Watts. Since one square meter is roughly 11 square feet, the “microwave burst” above is around 1.5 Watts/meter squared. The additional steady state heating can thus be equated to what one might expect if one illuminated a one meter square patch of ground with a flashlight.
Most of us would not expect to die of heat exhaustion even on a hot and sunny day because somebody turned a flashlight on and held it on us. Most of us would not expect to be able to feel the difference in temperature produced by a flashlight held a meter or more away, no matter how long it was left on, because any increase in temperature due to the flashlight bulb would quickly be swept away and degraded, literally lost in the noise of the usual round of much, much larger variations in light/heat in the diurnal cycle that are, nevertheless, stabilized by negative feedback.
An alternative picture might be covering the earth with Christmas tree lights spaced out a meters or so apart in a grid. Not exactly a picture of life threatening heat compared to microwaves, and even this makes assumptions that have not been directly measured — such as the actual variation of the total atmospheric radiative effect due to a hypothetical doubling of CO_2 concentration. The atmosphere is already saturated with CO_2 and the total CO_2-linked forcing is, as pointed out above, not a single variable linear function of CO_2 concentration.


The microwave grill is in one disgusting league with the Hiroshima bomb analogy.
The real context is given by Rosenthal et al 2013.
If you look at Figure 1 (Rosenthal figure 3B), it takes about 300-400 more years of recent (1955-2010) warming, just to get back to ocean temperatures of a 1000 years ago.
If you look at Figure 2 (Rosenthal figure 2C), it takes about 1000 more years of recent (1955-2010) warming, to get back to the maximum temperatures of the Holocene.

Rud Istvan

The stupid burns. See rgbatduke lest you cannot grok for yourselves.
RP sr, how did you not counsel JR into not getting into such a situation.
Debating with morons cannot end well. Never did, never will.


Do all climate scientist understand that earth rotates inside a magnetic field and that the sun is always plugged in to the same spot. There is no night and day side regarding the atmosphere it’s the earth that rotates .

M Seward

Trenberth really is a goose, isn’t he.
Comparing a half hour burst from a microwave oven to six mongths of CO2 induced GHG effect only establishes how tiny the GHG effect actually is if it takes a factor of time exposure of 15.77 million to deliver the same amount of energy!
Put another way, the 0.5 watts/sq metre-second or so of CO2 GHG effect is equivalent to 0.79 grams of water evaporated per square metre per hour ( 0.22 x 10^-3 grams per sq m per second). What he is really demonstrating is just how feeble the CO2 GHG effect is and much more significantly how easily it might be offset or drowned out by other phenomena that affect the climate system.


If it starts cooling the politicians can promise a chicken in every pot and a microwave over every square foot.


Is it possible that you have just discovered what people say about analogies? – ‘They rarely work.’
Not sure this late find is worthy of a news item, though 😉


Greetings from Oz.
Guys, the “microwave” analogy is just another classic example of Dis-Information being peddled by the Warmistas. It was not meant to be scientific, or even sensible – it was purely meant to create an impression, in the impressionable minds of the masses, of the correctness or importance of the author’s story versus his opponents. That is what the technique of Dis-Information is about! Please, look up the definition of dis-information on Wikipedia and check for yourself. This is NOT about the science, its mass mental manipulation by media!


How many terrawatts of microwave energy is forced through the atmosphere 24/7 by our communication networks and remote sensing ???


but it’s the power of 10,000 tasers!
meanwhile, still waiting for something meaningful to happen.
meaningful, as in prosecution, of course.


The world consumed ~552849.27*10^15 Joules of energy in 2010. That’s a rate of ~175190.96*10^8 Watts. The Earth has a surface area of ~5101*10^11 square meters. That means that we consume, all ~7 billion of us, consume energy at a rate equivalent to just ~0.03 W/m^2.
Seems to me like mankind’s real enemy is entropy. If we could harness the putative climate forcing as an energy source, a doubling of CO2 allegedly supplies energy at a rate almost 108 times as fast as we presently consume it.


@jmorpuss – 8:33 – waaaa?
Are you saying the atmosphere is static and the sun shines on the same place all the time?
Never heard it put that before. Wouldn’t that make for some REALLY fast wind speeds somewhere 🙂


Thanks Roger, and thanks rgb. I read a lot of product announcements from new vendors in the technology industry, often 10 a week. Always on the lookout for new technologies that can solve problems for my customers, the “next big thing” if you will. The problem is that the next big thing doesn’t come around nearly as often as it used to these days, but the number of new products appearing in the market has increased markedly. In other words, there is a lot of total cr*p out there.
The telltale sign of a product that is not worth digging into in any detail is the use of analogies that only indirectly quantify the features and benefits of the product. Good products explain their features and the value of them. Bad products hide their poor value through vague assertions that cannot easily be quantified, but sure sound good on the surface. That’s what Trenberth has done here in my opinion.
Had he simply said the earth surface gets about 241 w/m2 and this effect would raise it to 241.15 w/m2, the audience would have gone…huh? That’s almost nothing! Hence the analogy that only indirectly quantifies the issue, but leaves the uniformed reader with an impression of an effect out of proportion to reality.
This isn’t climate science.
It is climate marketing.


@ Hysteria
The pause lines are were the atmosphere stops working up and down (convection) and air moves north south (conduction) these pause lines are electromagnetic field lines and create a closed system NO greenhouse effect without this process. As man digs away the crust we speed up the natural radiative decay process created by the 6000k core. Winds at the surface are created by the interaction of aerosols positive ions (high pressure system) working in the down direction and electrons negative ions (low pressure system) working in the up direction . There is a scattering from mountain ranges and land mass both in the atmosphere and oceans because of rotation.


The concept of ‘Forciing’, predicated on the existence of the ‘Enhanced Greenhouse Effect’, is unscientific. If true, it would be a Perpetual Motion Machine of the 2nd Kind.
In reality, each self-absorbed GHG emission band in the direction of the Earth’s surface annihilates on average the same wavelength range from the surface. This means there is zero net surface IR emission in those bands, most of the IR spectrum.
The Trenberth Energy budget is otherwise correct. The microwave or any other such analogy is fake fizzicks. It’s time we put it to the sword.

John F. Hultquist

In the kitchen, many folks use “to nuke” interchangeably with “to microwave.”
Keven T. switched the pea under the shell. The average person has no idea what heat in the context of a microwave oven means but does know what a “nuke” can do – big mushroom cloud, buildings blown down, steel melted. All bad. Kevin inserted “the monster” under a shell and no one noticed the subliminal message. Weepy Bill Mc., Nye the nut, and fellow travelers must be cheering.

Phillip Bratby

Travest Trenberth is a master of deception (done in aid of a good cause of course).


Forget the half-hour microwave analogy.
It’s equivalent to the constant energy consumption of 2 alarmist climate scientists.
I just made that up, but does it matter? 🙂


February 19, 2014 at 8:17 pm | rgbatduke says:
Ahh! rgb, you’ve done it again (think McCain tinned foods ad if you’re an Aussie)


My problem is that, for example, the Sahara desert can vary by 35C over a day. It will have just as much CO2 as elsewhere, and other GHGs. To say CO2 may affect this by a fraction of a degree seems meaningless. What is lacking is water, which is not a GHG.
I would say that the Sun and water on Earth [in all its’ forms] determines 99% of the climate, For example there is the 60 year cycle of warming and cooling caused by the Sun and the oceans, on top of a warming trend from 1800. So 1910-1940 [warming] 1940-1970 [flat/slight cooling] 1970-2000 [warming 2000-2030 [flat/ slight cooling].
This well established cycle is responsible for ‘the pause’ and it seems totally incredible that climate ‘scientists’ refuse to acknowledge it exists! Okay, I appreciate that 97% of climate ‘scientists’ realise they couldn’t get a job elsewhere if the money stopped flowing so they may be desperate to keep the meme going [although I suspect quite a few don’t have a clue about the real climate anyway!]

Ivor Ward

Could someone translate this into the number of atomic bombs per Manhattan so that we ordinary people can understand. While you are at it, how many cuddly polar bears will it kill?

george e. smith

Well I think Dr Kevin Trenberth’s 1/2 hour microwave goosing, is right on the mark; for him.
He after all is the one who thinks that the sun shines on the earth at 342 Watts per square meter, which doesn’t have a snowball’s chance in hell of heating the surface, even to the alleged mean global Temperature of 288 K, for which the black body total emittance is about 390 W/m^2.
Try 1366 W/m^2 Kevin, and a light will go on in your head, as to why tropical deserts can easily warm up to 60 deg. C in a few hours.
I add as a footnote, that WATTS is a unit of power, such as a RATE at which energy is supplied or processed, or in any other way accounted for. It is not the average of anything, it is instantaneous.
Tropical storm / hurricane Sandy really didn’t do much; on average, during its visit from Africa across the Atlantic ocean. It’s only if you cherry pick some data, while it was in the vicinity of some frail structures too near the US coast, that much of anything happened. And, if such things, can take down the coast itself, then why would one expect flimsy structures to survive.
If Kevin believed; as I do, that “climate” is the integral of weather, instead of the average of weather, then it would all be clear to him.


According to Kevin Trenberth’s CV he is a
“Nobel Laureate (shared) for Nobel Peace Prize 2007 (as part of IPCC)”
It doesn’t say much for a person who has to pretend to be a Nobel Laureate! Such a travesty! Someone should be fired!

i) The effect of our emissions would be too small to notice compared to natural changes in energy flows.
ii) Any effect would be mostly or if not entirely cancelled by negative system responses.
iii) If there were any net effect it would result in air circulation changes which would be too small to measure compared to naturally induced variations from sun and oceans.
iv) The hydrological cycle is far more powerful than CO2 and helps to effect the negative system response (not the positive system response assumed by AGW theory).
The implication of all that is that the negative system responses, being able to work against the effects of non condensing GHGs such as CO2, must be working back towards a basic system energy content that is NOT significantly changed by those GHGs.
What sets that basic system energy content towards which the negative system responses always work back towards ?
If one excludes GHGs what is left ?


Ignoring an inconvenient truth never has stopped a true CAGW believer. In fact, as M. Mann demonstrated, covering up the truth is the preferred method.

The other misleading part of the microwave analogy is the we all know microwave radiation is dangerous to like. It cooks meat and vegetables. (See: woman puts poodle in microwave to dry it off)
LWIR is a lot less dangerous at an equivalent power density.
Why refer to “a microwave [oven]” instead of a simple electric oven. Because it’s intended that the listener will see it as dangerous.
Kevin Trenberth is well aware of basic physics, so that is further indication of his knowing intent to mislead the listener.

dangerous to _life_


Who comes up with these bizarre analogies like a microwave, or the ridiculous Hiroshima metric. I work in science everyday and analogies like these imply nothing to me. Do the general public really understand these meaningless comments, seriously?


It looks like they have changed there heading.

“Is climate change causing extreme weather? Experts disagree”

has changed to

“Experts explore whether climate change is causing extreme weather”

See the old headline in Google cache


I meant
“It looks like they have changed their heading.”


Trenberth does argue for more droughts: “The droughts set in a little quicker, they can be more intense, they can become more widespread.”
“We saw this in spades in 2012,” Trenberth said.

We also saw this in spades during the last ~11,000 years of the Holocene. There was “persistent drought” in California lasting for over 200 years before AD 1300! I have many, many other examples of extreme climate change and mine are actually CLIMATE and not the weather. They made it very clear some years back that the weather is NOT THE SAME AS THE CLIMATE!
Like I said before they are getting so desperate they now point to weather events to back there climate getting worse because of man claims. Why is it that the great authority, the IPCC, does not come to such conclusions? How Trenberth ever made it to be an IPCC author is beyond me. This is sad to watch, the desperation.


hitting yourself on the head constantly with a mallet can be bad for you. To put it in context, it’s as bad as listening to Trenberth for half an hour every six months

old construction worker

Mike Tremblay says:
February 19, 2014 at 7:55 pm “When you start involving radiative forcing in …….are the main contributing factors to why deserts have such a variation between night and day temperatures.”
Thank you. I’ve been saying that for years. It’s the reason why Swamp Coolers worked well in Arizona but not to well in Florida.


For those, like Trenberth, who insist on seeing climate change in the weather here are many examples of floods, droughts, storms etc. from 1709 to 1989. As you may know there are plenty more between, and before those dates.
Show me the trends then show me it’s not caused by natural climate changes, then show me it’s not caused by land use changes, soot and other non-greenhouse gases then I might listen to the likes of Trenberth. This is the sceptical position I believe and very reasonable indeed.


Imagine a promoter of AGW misrepresenting the facts of the case in order to sell more fear. /sarc off
The consistent pattern of AGW opinion leaders misleading the public is a compelling insight into their quality of work.

Crispin in Waterloo

Water is not a GHG but water vapour is. I think your post needs a couple of edits. A desert floor heats rapidly because there is little to block the incoming sunlight. At night it cools rapidly because if the low water vapour concentration overhead.
In a real desert like the Sahara, there are months when the sun cannot be clearly discerned because of the large amount of dust in the air, yet it gets quite hot anyway and still cools a lot. Water vapour is the most important insulator we have.
“Seems to me like mankind’s real enemy is entropy.”
A friend of a friend used to consistently throw rocks uphill. When my friend asked why he did that, he replied, “I am staving off the heat death of the universe.”
True, that, in a philosophical way.


“Where it is raining, it rains harder,” Trenberth said. “So at both ends of the water cycle we have an increased risk of drought and an increased risk of flooding in association with climate change.”

Where is the peer reviewed evidence showing a) it is happening, b) it’s caused or made ‘worse’ by man’s greenhouse gases? Is Trenberth now asking his fellow Warmists to break with IPCC findings / or lack thereof and believe his claims? Does he realise what he is actually saying here?

Pielke disagreed, arguing current data from the IPCC shows no increase in flooding and there is also no certainty that flooding will increase in the future….
The data doesn’t support that argument, Pielke said. The 1930s and 1950s saw worse floods, droughts and hurricanes than we see now….


So the challenge from Trenberth is “ … can you prove there is not an effect?” Spoken like a true climate scientist, one who really understands the very essence of science.

Olaf Koenders

From Hiroshima bombs to microwave ovens.. Next they’ll be using Google searches as an analogy – all fake and distracting anyway. All it has to do is make headlines as their religion rots around them.


Dr. Trenberth misuses the null hypothesis. He relies on magical explanations to find missing heat. He offers a filibuster to explain the pause. And now he needs to deceive us by way of microwaving the Earth for an analogy. A pattern seems to emerge…..

Bill Illis

If the Earth’s surface was receiving EM radiation in the microwave spectrum or the gamma-ray/x-ray/infrared spectrum of nuclear explosions, then Trenberth’s analogy would be a good one.
Since the Earth’s surface sees extremely, extremely small amounts of this type of radiation emitted from deep space and absolutely none from CO2 in the atmosphere, then it is a very poor analogy.
If the Earth’s surface was receiving microwave radiation at 2,450 megahertz, the oceans wouldn’t be around very long. They would boil away in a short time and get even hotter in the atmosphere. Its how your microwave oven works.

Vince Causey

Its like those shady salesmen who tell you that you’ll only be paying the equivalent of a cup of coffee a day or some analogy to create the illusion of not paying a lot. The reality when confronted by such spin is that you are being conned.


Can we call Trenberth a troll now?


At the end of the day, it matters not what Trenberth says because he’s a ‘CO2 man’ rather than a ‘solar man’. I think Trenberth needs to read “The Neglected Sun” (by Fritz Vahrenholt & Sebastian Luning) and learn about the solar cycles and effects that correlate nicely with weather and climate events. Truth is, people like Trenberth have always overly exaggerated the role of CO2 on weather and climate.