For the sake of those with the guts to face hard science, who are willing to invest enough actual thought to learn something more complicated than soundbites and platitudes, we’ll address some of the mistakes in Joe Bastardi’s comment. There are too many to address them all in one blog post. So let’s start small, with just the first paragraph:



When one pushes an empty cart and then stops pushing, the cart keeps moving until the work done on it is dissipated. How is it, that the earths temperature has leveled off, if co2 continues to rise and it is supposed to be what is causing the rise.. The answer is obvious. it is the earths temperature which is driving the co2 release into the atmosphere. That is what Salby opines, and he is correct.



Congratulations, Joe, you’ve managed to squeeze quite a few fallacies into a single paragraph. Impressive indeed.

Consider the first sentence:



When one pushes an empty cart and then stops pushing, the cart keeps moving until the work done on it is dissipated.



Objects in motion have an inherent tendency to keep moving. We’ve known about this since the days of Galileo, and Newton formalized the principle as his first law of motion. It applies to massive objects in motion (or at rest, for that matter). It does not apply to global temperature. There is no such thing as an inherent tendency to “keep warming” or “keep cooling.” If there were, then that would violate the first law of thermodynamics.

If Bastardi is suggesting that our climate system exhibits such a tendency, he’s mind-numbingly wrong. If not, then what’s the point of his very first sentence?

Let’s move on to the second sentence:



How is it, that the earths temperature has leveled off, if co2 continues to rise and it is supposed to be what is causing the rise..



I’m so glad you asked.

This offers a fine illustration of the fact that simplistic one-liners aren’t sufficient to understand what’s going on. There are three parts to the answer. Let’s hope that’s not too much for Joe Bastardi to handle.

First: Natural variability can mask a rising trend on short time scales.

Second: Many things affect global temperature in addition to greenhouse gases.

Third: It hasn’t leveled off.

Let’s consider each in turn. First, take a look at this obvious downward trend in temperature data:

We can even put it into context with more data:

It sure looks like temperature has “leveled off” since 1998 — in fact, perhaps since 1996 or even earlier! That’s obvious, right?

The problem with that conclusion is that these are not temperature data. They’re artificial data. They were constructed by combining a constant upward trend at 0.018 deg.C/yr (about the same as in the real world) with random noise having a standard deviation of 0.1 deg.C (about the same as in the real world). There is absolutely no doubt, none whatsoever, that the actual trend is not only upward, it’s at exactly the same rate throughout, it didn’t stop or slow down or level off. We can be quite certain, because the data were made that way.

I didn’t get that by generating lots and lots of random data sets until I found one showing this behavior. I just created one such data set, and there it was. It illustrates the fact that on short time scales, the appearance can be misleading, which is entirely due to the noise in the data, while the signal simply continues its increase at the same rate for the entire time span.

It’s the very nature of statistics that not only is is possible for false trend reversals to appear for no other reason than random noise, it’s actually inevitable. In fact it’s even easier for this to happen with real global temperature, because the randomness exhibits autocorrelation. That’s why, if you really want to know whether or not global temperature has leveled off, you have to apply significance tests, you have to compensate for autocorrelation, you even have to allow for the fact that a 130-year (or 160-year) record gives you lots of chances to see such behavior just by accident.

Has Joe Bastardi done that?

Let’s move along to the second point. It’s common for fake skeptics to claim that real climate scientists ignore everything which affects global temperature except greenhouse gases. The opposite is true. In fact it’s the real climate scientists who identify those other forcings and study their behavior scientifically, including such things as variations in the output of the sun, explosive volcanic eruptions, and the el Nino southern oscillation.

We can even approximate the impact of these other factors on recent temperature changes. I’ve done so myself; here for instance is the match between known factors and the global temperature data from NASA GISS:

Well, whattaya know? Those other factors really do affect global temperature!

If we remove the non-global-warming factors (solar variation, volcanic eruptions, el Nino), then we’ll get a much clearer picture of how global temperature is changing due to global warming (you know, from the increase in greenhouse gases). I’ve done that too. Here it is, not just for data from NASA GISS, but for all five major global temperature records:

Please note that the global warming part (from greenhouse gases) hasn’t stopped. In fact, it hasn’t even slowed down.

On to the third point. Even if we don’t account for those other factors which affect temperature, global temperature hasn’t leveled off. Bastardi says later in his comment that



… earths temps have leveled off the past 15 years …”



To get some context for the last 15 years, let’s begin by looking at the past 36 years:

I’ve added a trend line (by linear regression) in blue. Now let’s add a trend line (in red) estimated using only the last 15 years:

Note that the trend over the last 15 years is no different from the trend over the last 36 years. Note also that the hottest year of all was last year, 2010. If this is Joe Bastardi’s idea of “leveled off,” then I wonder what’s his idea of “global warming.”

Some would object that you have to use a different data set (like the data from HadCRU, or NCDC, or RSS, or UAH) to see that it’s leveled off over the last 15 years. Unfortunately — for them — it ain’t so:

All five data sets show an upward slope over the last 15 years.

Let’s finish off an already long post with Joe’s final sentences from his first paragraph:



The answer is obvious. it is the earths temperature which is driving the co2 release into the atmosphere. That is what Salby opines, and he is correct.



Joe, please. Even if you were right about the basic facts (which you’re not), this is a logical fallacy. Do you really not get this?

Then there’s this little matter:

Boy, that’s one hell of a hockey stick. If you really believe that temperature controls CO 2 , then temperature must have been remarkably stable until the industrial revolution starts and you can say goodbye to the “medieval warm period” and the “little ice age.” But quite by coincidence CO 2 starts to rise at exactly the time that we (humans) started pumping CO 2 into the atmosphere — even more CO 2 than has accumulated since that time. What an astounding coincidence that is!

It’s also an amazing coincidence that the added CO 2 in the atmosphere since the industrial revolution has shown exactly the “isotopic signature” of fossil-fuel CO 2 . For one thing, that means that it has less carbon-13 than volcanic or oceanic CO 2 because it’s “biogenic” carbon (from plant matter, in this case long-dead plant matter). And for Murry Salby’s information (he discussed the carbon-13 issue), it’s also not modern biogenic carbon because it has vastly less carbon-14 (the “other” rare isotope) than modern biogenic CO 2 . In fact, the “Suess effect” which originally identified fossil fuels as the source of CO 2 increase, at first wasn’t about carbon-13, it was all about the carbon-14.

Let’s not ignore yet another astounding coincidence, that the amount of carbon in both the oceans and in the biosphere is also increasing.

So: carbon is coming from somewhere — God only knows where — but it’s not the oceans because oceanic carbon is increasing, it’s not the biosphere because biospheric carbon is increasing, it can’t be from volcanoes because it has the exact isotopic signature of fossilized biogenic carbon. But it’s not from fossil fuels because Murry Salby says so, even though it starts its increase just when we start burning fossil fuels in large quantities.

How gullible do you have to be to believe this? No real skeptic would swallow that. Only a fake skeptic could.

These are some valuable lessons here. For one thing, the statistical behavior of global temperature (and just about everything) is quite more intricate than meets the eye. For another thing, the evidence that CO 2 increase is due to human activity is overwhelming. Perhaps the most important lesson is that fake skeptics aren’t really skeptical at all. Joe Bastardi and his comrades are the epitome of gullibility.

These are just a few of the more obvious mistakes in Joe Bastardi’s comment. But we only got to the first paragraph.