Can you and your knowledgeable readers help me get a better understanding of Atlantic tropical storm forecasts, please? I began by noticing the Met Office forecast numbers for the 2007 hurricane season are lower than those provided by scientists at NOAA CPC/NHC/HRD/HPC. Then I read about the Met Office’s relatively new methodology: it is interesting and quite different from that of traditional tropical storm forecasting systems.

I would appreciate some background history, especially to the forecasting of sea surface temperatures. The Met Office predicts North Atlantic SSTs cooling while NOAA and other forecasters emphasise SSTs warming (hence storms increasing) for this 2007 season. I have no idea how reliable tropical storm forecasts have been in previous years, nor whether the Official numbers published by NHC would include these new-kid-on-the-storm-block Met Office forecasts.

This is what I have discovered so far today.

BTW, regarding the HS and the TAR, the problem was never with the study itself but with the emphasis placed on it; IOW, it was used as a symbol of the extent of our knowledge about climate. One can argue about whether it was a good idea to do that, but the inevitable result was six years of trench warfare over the details of a single, relatively early paper that was never very important in terms of the main conclusions of the TAR. Another benefit of using the HS in that way (recalling that the great emphasis was in the aptly-named Summary for *Policymakers*) was to implicitly answer what might be called the first ignorant question about climate, i.e.: How do we know this kind of thing isn’t a common event in climate history? I say ignorant because of course the key point is that even if such temp excursions were found to be relatively common, the cause and rate of the present warming is unique. Very fortunately the HS debate is mostly behind us now, and even the Climate Audit crowd has moved on to attacking the surface record and the models (although now it’s mostly just for their own amusement; they lack the expertise to engage on the models and Phil Jones et al are pretty much free to ignore them on surface temp issues.)

The answer has to do with the fact that, for all practical purposes Mars does not have an atmosphere (the atmospheric pressure at the surface is low 7 mbar in winter, 9 in summer, the Earths is 1 bar at the surface, a mbar is a thousandth of a bar) and is mostly CO2 with a trace of water. That is a variation of 30% or so between summer and winter. melting the poles will inject more CO2 and probably a relatively high amount of water vapor…..and then you get an enhanced greenhouse effect.

In that case the forcing is orbital, and the feedback is polar melting releasing greenhouse gases, much as what is thought to have happened in the ice ages, where the melting of the ice caps due to orbital changes (Milankovitch cycles), resulted in a release of CO2 trapped in the ice, permafrost and the oceans (warm coke effect).

Today we have taken over for the Celestrial Mechanic, and just simply dumped a bunch of CO2 in the atmosphere. Same effect.

The second is what happens to the rate of melting of the ice caps and shelfs in Greenland and Antartica (most other ice sheets are small change) as temperatures change. At the time of the TAR it was thought that the response of the ice sheets was well enough known to estimate this and that the process would take hundreds of years under the various warming scenerios.

Please understand that the question about what the ULTIMATE sea level rise would be for a particular temperature scenerio is well known, and that Gore is absolutely right when he says that if the global temperature goes up 5 C or so, ice caps will melt and the sea level rise will be 20-30 feet. The real issue is WHEN this will happen, e.g. how fast.

Recent (within 2-3 years) measurements have shown that our understanding of ice sheet behavior is incomplete, and that the Greenland ice sheet is moving into the sea at a much FASTER rate than was assumed for the TAR. Thus the AR4 summary said, hey wait, lets take this second part out of our estimate and invest a lot more time and effort into trying to understand ice sheet dynamics.

Thus, the major threat is no longer included in the estimate of sea level rise, because we simply don’t know enough about it, except that it is a very serious issue. You can hear Jim Hansen talk about this by following this link

[Response: Indeed, thanks for the correction. One might argue that they *can* be run backwards -- but to my knowledge this has never been done, and you've certainly characterized the actual situation correctly.]

As an aside, in my experience, people like Fillmore can never retract a statement they have made. It is my acid test about whether the argument will be interesting and/or useful.

In light of Timino’s comments above, are there any statements that you are willing to retract? If not, why not?

[Response: After the last round of exchanges, I recieved some rather nasty comments from Millard which prompted me to use the "delete" button. This is not a site for pointless argument, and I think further comments from Millard would be pointless.]

I miss your visits since we moved.

Oh, and Al Gore did flunk (or drop, I can find references for both) out of graduate school. I can’t recall which one, wait (praise Google), it was Vanderbilt, possibly because he was more interested in Tipper than his classes.

the Grit

[Response: Alas, while we should be discussing what can be done to avoid environmental disaster without inviting economic disaster, instead we're pondering whether Al Gore dropped out of Vanderbilt because he was more interested in romancing his future wife than studying for his mid-terms.

I continue to use the tag surfer, and I'll "drop in" from time to time.]