9) All but the latest, have been associated with volcanic cooling (Santa Maria,Helkla, Agung) and/or El Nino type perturbations.

What volcanic cooling and/or El Nino type perturbations were responsible for 1945-1955 and 1965-1975?

Anyone else wanting to answer, get them in ASAP. An interesting lack of named climate scientists participating . . . hmmm;-)

It does not matter because the information is meaningless.

Or

The time period is too short to care and so not useful for policy matters.
Or

It’s natural variability.

If your point 4 referred only to volcanoes, then there’s no objection at all.

I was thinking about the ‘large cooling anomaly’ (in the context of the 20th century) of the mid 40s to the mid 70s. Aerosols are also used to explain it, quite unconvincingly, IMHO.

The other objection stands though.

I’m not sure I understand your objection.

Item 4 concerns the effects of the aerosols from large volcanic eruptions (much larger than regional human aerosol emissions). Virtually everybody agrees that these events correlate strongly (as the physics predicts) with short cooling spells.

Len

In your list of nine “widely agreed generalizations” you include one, 4, that is not at all widely agreed upon: the mid 20th century cooling due to (sulphate) aerosols. As it happens, I think it’s the most important of your 9 points. If the reason for that cooling had been anthropogenic aerosols (that is, tropospheric sulphates), the consequences would have been regional and relatively easy to detect. We should also be detecting them now in some Asiatic regions, which we’re not doing. However the cooling was global. According to HadCRUT, the global was actually more pronounced in the SH, which pretty much invalidates your assumption (and hints to undetected causes for climate/weather variability, perhaps including the current flat trend).

Also, you conclude: “If the current temperature ‘flat’ is due to … a ‘burp’ in surface to deep water flux, then we can expect warming to resume shortly, and GCM long-term predictions will probably be trivially effected”. In my previous post I tried to show in an intuitively way why, irrespective of the reason for the current stasis, the particular prediction of +0.2 C /decade for the period ‘00-’30 is increasingly unlikely to succeed. We would have to see a sustained resumption of increasingly high anomalies. It hasn’t happened in the past. It’s also hardly consistent with the very prediction of a stable trend for this period.

Talk about meaningless exercises, I went to your page and saw first off your quote of the National Geographic scale of “sustainable” countries. I noticed Brazil was #1. Did you know that Brazil is #1 in destruction of tropical rain forest:
http://www.mongabay.com/deforestation_rate_tables.htm

You have to remember you are getting your information from a periodical that increasingly is turning to *selling* than illumination. Same goes for Scientific American etc., and even the gray scientific journals of Science and Nature. The way it I heard it best was “The press doesn’t write about planes that don’t crash”.

Back to the subject at hand, I agree that 7 years is not enough time here. However, considering a few years ago an alarmist guru gave us 10 years “to act” or we’re all gonna die, it seemed like 7 was enough. In fact, the amount of time to determine anthropogenic climate change depends on it’s relative magnitude compared with natural variability. The longer we go like we are (actually cooling this century) the less of an emergency it is, so why panic (and destroy rainforest, starve people to make ethanol, reduce third world countries ability to advance, etc.)

Are you aware that the rate of temperature decline out of the Little Ice Age was the same as the rate of temperature decline out of the Eemian Interglacial? *That’s* climate. 7 years isn’t. Neither is 30.

Instead spend more time sharing science data that is actionable, as for instance:
http://lamarguerite.wordpress.com/2008/05/09/must-read-greendex-international-study-of-consumers-and-sustainability/

We’re basically in agreement.

Len Ornstein