Guest Post by Willis Eschenbach

I was thinking about “dust devils”, the little whirlwinds of dust that you see on a hot day, and they reminded me that we get dulled by familiarity with the wonders of our planet. Suppose, for example, that “back in the olden days” your family lived for generations in a village on a tiny island where there were no clouds. None at all. Ever.

Now, imagine the consternation that would occur if one day, after centuries without a single cloud, a big fluffy white cumulus cloud suddenly popped into existence one afternoon right over the village, hung around for six hours, and then disappeared in the evening. If it happened once, it would pass into legend as the giant white boulder in the sky that threatened to crush the village, and only disappeared after the priests did their most powerful chants …

Next, imagine that over time the appearance of the clouds became more common, but the priests always successfully chased them off … until one day, a plain old white fluffy cloud suddenly started growing straight towards the sky, and it turned black, and miracle of miracles, pure water started pouring out of the cloud! The cloud turned into a fountain! Who knew? If it happened once, it would be spoken of for years.

Next, imagine that over time, the appearance of rain clouds became more common, and the priests tried to make them stick around … until one day the priests were out doing their rain dance in the pouring rain, when without warning, there was a blinding flash of light and a tremendous sound, and all of the priests were knocked dead by some strange, unknown power … imagine the consternation and wonder that would cause, and what kind of legends that would engender …

I bring all this up to highlight the nature of something called an “emergent phenomenon”. The cumulus cloud is an example of an emergent phenomenon. The rainstorms are a second, different emergent phenomenon. Finally, the lightning is a third example of an emergent phenomenon.

So … what are the characteristics of such a creature? How can we tell an emergent phenomenon from all the other inhabitants of the zoo? The following is not an exhaustive list, and some don’t have every characteristic, but here are the things that set an emergent phenomenon apart from its cousins.

• It has a “lifespan”—it is called “emergent” because it emerges from the background conditions at a certain time, lasts for a certain span of time, and then dies out.

• It emerges spontaneously whenever conditions are favorable, and never emerges otherwise. Often this is associated with the passing of some threshold, with emergence not happening at all below the threshold, and increasing quickly once the threshold is passed.

• It has “edges” that make it clearly distiguishable from its surrounding background.

• It must constantly change and adapt to current conditions in order to persist in time.

• It may split into two or more independent copies of itself.

• It can move independently through its surroundings.

• It can do work on its surroundings.

• Once it emerges, it can persist through conditions below the threshold for emergence.

• It is unexpected in the sense that it is not intuitively predictable from the previous conditions. For example, there is nothing about a clear blue sky that says “here come fluffy white clouds”. There is nothing about white fluffy clouds that screams “Close your car windows.” And there is certainly nothing about a warm summer rain that warns “Don’t stand out in a field or a million volts of electricity might pass directly through your corpus delecti …”.

What does this have to do with climate? Well, emergent phenomena are the missing link in the climate models. They are what keep the planet from overheating.

See, the planet is in a funny position. We’re only running at about 70% throttle. About 30% of the sunlight hitting the planet never makes it into the climate system. So never mind CO2, there’s enough energy from the sun to fry us all to a crisp … but that’s never happened.

The reason it hasn’t happened is that there are a host of emergent phenomena that stand in the way of overheating … which brings me back to the dust devils. Here’s a photo I took of some dust devils at night, cooling the surface of the desert from the effects of the huge fire at the left of the picture … dust devils don’t care about the source of the heat.

Now, dust devils have all the characteristics of typical emergent phenomena—they have a lifespan, the do work on their surroundings, they move independently, they change and adapt, they are not intuitively predictable from calm air. In this photo they were emerging next to the fire, then spinning off to the right into conditions where the surface is too cool for them to emerge. So they fulfill all the requirements, they are emergent phenomena … and given that the dust devils do work, then what is the dust devil’s day job? That is to say, what work is a dust devil doing on the surroundings?

The answer is, it is cooling the surface in a several ways. First, it is taking warm surface air and spiraling it up rapidly to altitude,  physically removing the heated air from the surface. Next, the increased speed of the wind increases evaporation, further cooling the surface. Next, wind on the earth’s surface increases the “wind chill factor”, which is the increased conduction of heat from surface to atmosphere via surface turbulence.

So a dust devil is a natural cooling machine, a fantastic piece of hardware that is very effective at reducing the surface temperature. And while that is amazing in itself, that’s not the beauty part …

The beauty part is that dust devils only emerge where and when they are needed, at the hot spots. If you’re looking a chunk of real estate, the spot where the dust devil emerges is where the heat is located. This makes it incredibly efficient. Consider how much energy it would take to cool the whole chunk of real estate, and how much less energy it takes to focus the cooling energy exactly where it is needed.

The same is true of the tropical clouds. You don’t want clouds in the tropics all the time, they would reflect all the sunshine, and the planet would cool way down. You only want clouds when it gets hot … which of course is exactly what happens on your average tropical day. In the cool of the tropical morning, it is clear. But when the surface warms, the clouds emerge, and if the warming continues, then the thunderstorms emerge as well.

So to complete the thought, the beauty part of emergent phenomena is that their thresholds are temperature-dependent. As a result, they are independent of both total forcing and total losses. This is a critical point. They are temperature-dependent, not forcing-dependent.

For example, clouds don’t emerge in the tropics when the sun is hot (forcing-dependent). Instead, they only emerge when the surface is hot (temperature-dependent).

And this is why changes in the forcings don’t have much effect on temperatures, particularly on the hot side of the range where the various phenomena emerge in untold numbers. Increases in forcing, whether from CO2, from volcanoes, or from the 5% increase in solar strength over the last half-billion years, don’t affect the temperature much because they don’t affect the emergence thresholds of clouds and dust-devils and thunderstorms. Instead, the emergence of these and other temperature-regulating phenomena is controlled by thresholds related to surface temperature and insensitive to forcing. As a result, the cooling phenomena emerge exactly as, when, and where they are needed, and their emergence is not a function of the forcing in any but the most indirect manner.

Finally, as I mentioned, we’re dulled by exposure to the radical, unusual nature of the emergent phenomena. As a result, for example, the numbers of dust devils could double, and nobody would be the wiser. We hardly notice them, yet they remove huge amounts of energy from the surface in the worlds’ hottest areas. Or, clouds could emerge fifteen minutes earlier in the tropics. Nobody would even remark on it. But either of those shifts would have a profound and lasting effect on the surface temperature …

And that’s why the climate models don’t explain much. They don’t have any of the many emergent mechanisms that preferentially cool the hot spots. No thunderstorms. No dust devils. No waterspouts. No cyclones … and without those temperature-sensitive heat-seeking surface-cooling mechanisms, the models don’t have a chance of reflecting reality.

Regards to all,

w.

NB: Please quote what you disagree with. I can defend my own words, and I am happy to do so. I can’t defend your interpretation of my words. Quote what you disagree with.