Denialists and echo chambers

Over at Armed and Dangerous, the global-warming denialists (I don't think "skeptics" is a fair descriptor) are in the majority.  This comment is typical:

The way I understand it, it is impossible to argue against global warming per se. The world is getting warmer, and that is provable. Just as the world got colder for the Little Ice Age.

The pseudoscience comes in with discussions about *why* the world is getting warmer, and what will happen in a warmer world, and what we should do about it. That's where you see most of the handwaving and the fudging the numbers.

Let's see. Temperatures have been on the rise since the early 1900s, but greenhouse gases have been on the rise since the 1950s or so. Hmm. Is there a link?

How is that wrong?  Let me count the ways:

1. Greenhouse gases have been on the rise since the 18^th century.
2. Warming is partly offset by reflective aerosols, but pollution controls are now reducing the counter-warming effects.
3. It is known quite conclusively that the temperature of the earth is much higher than its blackbody equilibrium (~255 K) would be save for greenhouse effects.  There is nothing pseudoscientific about projecting an increase in temperature from increased greenhouse gases; on the contrary, the denial is pseudoscientific and there is a great deal of science going on to quantify the phenomena and feedback influences.
4. It is known conclusively that atmospheric CO₂ concentrations are higher now than at any time in the last several glacial cycles, and this is entirely explainable by human activities.

Before we got in the habit of burning coal and oil, the atmosphere's CO₂ level varied like this:

The highest pre-industrial CO₂ concentration determined from ice-core data was 298.7 ppm a bit over 320,000 years ago.

Recent history is very, very different:

We're now up to ~380 ppm and rising at about 2 ppm/year (data).  There is no honest way to deny this.  Carbon dioxide is a major greenhouse gas and is one of the determinants of the troposphere/stratosphere boundary (which is where convective transport of heat ends and radiative transport takes over); there's no informed, principled denial of that either.  The deeper the convective layer (which is too "optically deep" at IR wavelengths for heat to escape by radiation), the hotter the surface; this follows by straightforward thermodynamics.  There are complications such as chaotic weather patterns, non-uniform and time-variable atmospheric and oceanic heat transport and more, but they do nothing to contradict the broader principles.

At Real Climate, there's a thread about skepticism which is very much on-point.  It starts with some pertinent observations by Bertrand Russell.  The money quote (all errors theirs):

There are matters about which those who have investigated them are agreed. There are other matters about which experts are not agreed. Even when experts all agree, they may well be mistaken. .... Nevertheless, the opinion of experts, when it is unanimous, must be accepted by non-experts as more likely to be right than the opposite opinion. The scepticism that I advocate amounts only to this: (1) that when the experts are agreed, the opposite opinion cannot be held to be certain; (2) that when they are not agreed, no opinion can be regarded as certain by a non-expert; and (3) that when they all hold that no sufficient grounds for a positive opinion exist, the ordinary man would do well to suspend his judgment.

The facts in this case are:

• The experts are essentially unanimous that human activities are causing the climate to change; their quibbling is over how much, and the paid industry shills don't count.
• Because of this, the claim that GW is merely a myth or political tactic is untenable and dishonest; it is just a rhetorical means of poisoning the well.

I am not a climate scientist.  The soi-disant skeptics (deniers) can say anything they want to or about me, and it proves nothing; what they need to do is come up with a model that is

1. A better predictor (and retrodictor) than the current climate models, and
2. Does not show any anthropogenic warming going forward.

Discussion here is pointless; I'll be reading there.

  ¶ 12/28/2005 02:58:00 PM