What do we know?

We know for a fact that CO2 slows the radiation of heat. We can measure in a tube the precise degree to which it slows the radiation of infrared, and in a tube that traps gasses physically, we know that slowing the radiation of infrared further traps heat.

Quantum Mechanics tells us this is true. We can precisely calculate the probability that a CO2 molecule will catch an infrared photon, and we have testable and, BTW, spectacularly well tested theories, that show that after a time, the molecule will either re-radiate the photon in some arbitrary direction, including down in the case of the atmosphere, or collide with another molecule, passing its heat on that way.

We also know that a body which is absorbing heat must radiate that heat in equal measure or it will warm. Slow the radiation of heat and the body will warm. Nobody disputes this.  We just don’t know anything right now about how the effects of a CO2 molecule, or any other molecule that can absorb infrared, shake out in a system as complex as that of our planet.

If one has an air cooled gasoline engine, one can’t just calculate that it will overheat or not based on the properties of the metals it is made of and the gasoline it burns, one must also take into account the configuration of that metal. Does it have cooling fins? That is a big part of the answer. In the case of the planet, it may be that the configuration of any “cooling fins” and their effectiveness is not readily apparent and that the sum of any heating and cooling effects caused by CO2 is not a tractable calculation, even if we had the measurements.

What can we do in a case like this? We can only measure the effect and infer the rate of warming caused by GHG based on measurements.  This is not perfect because it is likely that climate effects such as ocean currents and oscillations, changes in biology, ice extent and volume changes, cloud cover variations, etc… are causing a kind of climactic Brownian Motion, hiding the signal in what, lacking deep understanding of these issues, we can only call noise.

That is where we are. We have an undoubted effect, but we can’t measure it except in the crudest manner. That is why the pause is as important as the jump in temperatures that preceded it. We can’t pretend that we “just know” that heat is building on the planet if we can’t see the planet heating on the grounds that “it must be somewhere” because it doesn’t have to be anywhere on the planet, it may be radiating away,  light years away, in the case of the pause.

And then there was Michael

Judith Curry published a guest post by Matt Skaggs which was a discussion of “Root Cause Analysis” of the current warming. Michael, a particularly prolific commenter at Judith’s site, makes a couple of comments:

“‘For years, climate scientists have followed reasoning that goes from climate model simulations to expert opinion, declaring that to be sufficient….’ Matt

Not a good start.”

OK, it was a long post, we can’t expect everybody to read the whole thing before commenting, but then he says :

“Tend to gloss over the fact of a century of temp obs.

Given the claimed importance of collecting data, it seems an odd thing to start with.”

So wait a minute… The post is about the root cause analysis of the “century of temp obs,” it grants that in its very premise.  However; this post is not about Michael, per se, it is about ineffective defenders of the consensus who do more harm than good. When a person with a reasonable grasp of the logic can see the obvious shortcomings of the commenter’s argument, skepticism grows.

This is not “how to talk to a skeptic.”  Advocates for the consensus position on AGW should realize that they have a responsibility to maintain high levels of discourse because their advocacy is the lens through which many see the case for AGW.

I am a climate agnostic. I know it is a very hard problem and the fact that it is a hard problem does not mean that it is not happening. I am skeptical of the case made so far, but not skeptical of the idea that AGW may be happening, I don’t know enough to be skeptical based on the case made so far. I am agnostic.


So much idiocy, so little time

From Wikipedia


Twenty-year smoothed plots of averaged ring-width (dashed) and tree-ring density (thick line), averaged across all sites, and shown as standardized anomalies from a common base (1881–1940), and compared with equivalent-area averages of mean April–September temperature anomalies (thin solid line). From Briffa et al. 1998.[1]

So we have a problem using tree rings to measure temperature. The problem is that as temperatures have risen in recent decades, the same tree rings that purport to show that the Medieval Warm Period (MWP) was not as warm as today, sort of peter out, you know, “decline.”  This is known as the Divergence Problem.  How does Wikipedia describe the possible causes of this issue?

The explanation for the divergence problem is still unclear, but is likely to represent the impact of some other climatic variable that is important to modern northern hemisphere forests but not significant before the 1950s. Rosanne D’Arrigo, senior research scientist at the Tree Ring Lab at Columbia University‘s Lamont-Doherty Earth Observatory, hypothesises that “beyond a certain threshold level of temperature the trees may become more stressed physiologically, especially if moisture availability does not increase at the same time.” Signs suggestive of such stress are visible from space, where satellite pictures show “evidence of browning in some northern vegetation despite recent warming.”

“[S]ome other climactic variable … not significant before the 1950s” Well that is convenient, isn’t it? You can explain anything by positing “some other variable.”

“beyond a certain threshold level of temperature the trees may become more stressed physiologically,

Do you think it is possible that during the MWP it was warm enough to stress the same trees as well? It’s a rhetorical question. Of course if it were very warm during the MWP, the same factors would likely apply.

In other words, Mann’s claim of today’s warming being “unprecedented in the past 1500 years” is not supported by the tree ring methodology that he uses.  The idea that some new unknown factor has come into play is just a fig leaf to avoid drawing the obvious conclusion.