Retired MIT climatologist Richard Lindzen needs no introduction around here. But if he did, his contribution to the Canary volume we’re reviewing in this series would serve nicely because it is a minor masterpiece in brevity and clarity. Beginning with his title, “The Absurdity of the Conventional Global Warming Narrative” which neatly conveys his exasperation after a career of trying to slow down society’s march into alarmist extremism. And the absurdity in question is its insolent oversimplification. He says “The conventional global warming narrative reduces an extraordinarily complex, dynamically regulated system to a small statistical anomaly attributed primarily to a trace gas that alters the radiative budget by only a few percent.... the prevailing narrative is not merely incomplete. It is profoundly misleading.” In his chapter he offers a few pointers to why the narrative reflects, in his words, “a failure to respect the complexity of the system itself.” Complexity? Is that thing still around?

Oh yes indeed. But it lurks behind one thing that is straightforward and that climate alarmists cite and then lazily rest their case. Thus Lindzen starts by explaining the basic “greenhouse” mechanism, with which he has no dispute.

Solar radiation enters the atmosphere and warms the surface. The energy needs to be radiated back to space, but the atmosphere absorbs the outgoing radiation in its lower layers, up to the “effective emission altitude”, the height at which the greenhouse effect is left behind and all outgoing radiation that makes it to that point then escapes freely to space. And yes, adding carbon dioxide to the atmosphere makes the absorbing layers thicker, so the effective emission altitude rises.

Moreover, since the EEA is in the thermosphere, where temperature decreases with height, this outgoing radiation is now emerging from a cooler layer of air. (Speaking of complexity, the atmosphere has five layers, the troposphere, stratosphere, mesosphere, thermosphere and exosphere and, weirdly, in both the stratosphere and the thermosphere temperature rises as you get further from the warm Earth and closer to chilly outer space.) As a result, less heat is radiating into space unless and until the surface temperature increases, and that temperature increase passes up through the atmosphere, to restore “radiative equilibrium”, the point at which as much is leaving as is coming in.

It is via this mechanism that doubling CO2 appears to lead to about one degree C of average warming. And on its own, a degree of warming is hardly noticeable; without modern thermometers we wouldn’t be aware of it at all. But Lindzen shows how with a few graphing tricks it can be made to look catastrophic. For instance, if instead of having the Y axis cover say 80˚C, which would be reasonable given that it’s roughly the span between the warmest and coldest points on the Earth’s surface at any one time, you have it only cover two degrees, it looks as if temperatures are soaring.

The jiggery-pokery doesn’t stop there. For all their loose talk of “simple physics” alarmists and their models actually contrive to generate a lot more than one degree of warming from a doubling of atmospheric CO2 by assuming a set of important feedback loops and assuming they are essentially all positive, thus amplifying the effect. But Lindzen disputes the assumption that positive feedbacks dominate, at least in the way models assume.

Yes, increased water vapor can increase formation of high cirrus clouds which absorb heat in the atmosphere. But his work on cirrus cloud formation revealed a potential decrease, rather than increase, in cirrus formation associated with sea surface warming, the so-called “Iris effect”.

Lindzen also points out that natural processes have produced much larger climate changes over history than anything humans are doing with greenhouse gases. For instance he notes that the big driver of the Earth’s weather system is not the average global temperature but the temperature difference between the equator and the poles. In all the past major geological epochs, the phenomenon of “global warming” or “global cooling” wasn’t global in the sense that you might expect. Instead the temperature of the tropics stayed about the same, whereas the polar regions warmed or cooled relative to the present by as much as 20 degrees. So what really changed with “climate change” wasn’t some misleading global average but the temperature difference across latitudes:

“large climate transitions are driven primarily by changes in temperature gradients rather than by uniform shifts in global temperatures.”

As we have noted before, unless you assume some kind of malevolent magic has been operating of late, it is not rational to believe that climate processes that operated for hundreds of millions of years suddenly stopped around the time disco died.

In the end Lindzen disputes that CO2 is the control knob of a simple one-dimensional system. The deep history of the planet, and the ongoing failure of models to capture important changes happening right now, vindicate his call for humility in the face of real complexity. And, we might add, a little more knowledge on the part of people who claim it’s all so simple.