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One of the things I find intriguing about the whole subject is why, if CO2 gets relatively evenly spread around the globe and also re-inforces any warming, there are these places which go against the trend. I would have expected global warming to be global, not to have spacial variations.

My gut feeling is that the warming from greenhouse gases at the surface is relatively tiny - currently 2 Watts per metre squared compared with a few hundred from the sun. So its effects on a local scale are not going to be noticeable on the timescale of movements of warm or cold air by the weather. As we see from the seasons, solar strength is slightly smaller in August than in May, but August is usually hotter because influences from the weather are significant.

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Originally posted by Steve_M:

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So from that basis I approached it. I also know three scientists personally (2 Astronomers and a Geologist) all of whom said that if the IPCC report was submitted by a student if would result in a failing grade.

This is a pretty outrageous claim given with no examples. The bits I've read seem reasonable to me.

OK. Then what about some of the claims to only use articles that have been peer-reviewed? Firstly, Phil Jones seems to have avoided this. Steve McIntyre, as an IPCC expert reviewer could not get hold of his data underlying his "debunking" of the UHI effect; and secondly at least one of the articles was peer-reviewed and then rejected by the peer!

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Originally posted by Steve_M:

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One of the things I find intriguing about the whole subject is why, if CO2 gets relatively evenly spread around the globe and also re-inforces any warming, there are these places which go against the trend. I would have expected global warming to be global, not to have spacial variations.

My gut feeling is that the warming from greenhouse gases at the surface is relatively tiny - currently 2 Watts per metre squared compared with a few hundred from the sun.....

So you're saying that greenhouse gases only account for, what, 0.5% compared with the sun?

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So you're saying that greenhouse gases only account for, what, 0.5% compared with the sun?

It might be clearer to say that the extra (anthropogenic) greenhouse gases are currently causing warming equivalent to what would happen if the sun were to warm by about 0.5%.

(not too sure about the exact percentage though - solar warmth affects us slightly differently to greenhouse gas warming)

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Originally posted by Steve_M:

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So you're saying that greenhouse gases only account for, what, 0.5% compared with the sun?

It might be clearer to say that the extra (anthropogenic) greenhouse gases are currently causing warming equivalent to what would happen if the sun were to warm by about 0.5%.

(not too sure about the exact percentage though - solar warmth affects us slightly differently to greenhouse gas warming)

Actually, I suspect the percentage is rather smaller than that. I believe that IPCC have reduced their estimate of man's contribution from 2.4 w/m2 to 1.6; this is compared with the sun's 1,318 (is that figure right?)

So, bearing in mind that, as you said on another thread, the sun is warming up anyway (albeit very slowly), all that all mankind's efforts have done is advance the process by a few years. Is this right?

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Actually, I suspect the percentage is rather smaller than that. I believe that IPCC have reduced their estimate of man's contribution from 2.4 w/m2 to 1.6; this is compared with the sun's 1,318 (is that figure right?)

The sun's output is 1366 W/m^2 (at the earth's distance from the sun). However, because the earth is a sphere, only the bit directly under the sun gets this (ie. the tropics at midday. The night side receives no radiation, the dawn, dusk and polar bits receive a lot less). The average radiation is therefore 1366 multiplied by area of the disk exposed to the sun, and divided by the total surface area of the earth.

=1366 times (pi * r * r) divided by (4 * pi * r * r)

(where r is radius of earth).

The pi's and r's cancel out so we get a result of 1366/4 = 341 W/m^2

The contribution of the greenhouse effect is given per unit earth's surface already, so 1.6/341 is about half a percent.

It is slightly more complicated because the UV component of the sun is absorbed in the upper atmosphere, so quite a bit less reaches the earth's surface.

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So, bearing in mind that, as you said on another thread, the sun is warming up anyway (albeit very slowly), all that all mankind's efforts have done is advance the process by a few years. Is this right?

Veeeery slowly. 1 percent every 100 million years - so far, we've advanced the process by 50 million years and by the end of the century another 75 million.

Something else dredged up from my astrophysics course is the fact that, while the sun has a good few billion years of stable life in her, in about a billion years the she will be warm enough to evaporate the oceans even if there are no greenhouse gases - so we'll have to move to Mars, and then plan for another move a few million years later to Europa. Hope that's not too much of a shock.

With that much warning, we should be able to get APEX tickets!

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OK. Then what about some of the claims to only use articles that have been peer-reviewed? Firstly, Phil Jones seems to have avoided this. Steve McIntyre, as an IPCC expert reviewer could not get hold of his data underlying his "debunking" of the UHI effect; and secondly at least one of the articles was peer-reviewed and then rejected by the peer!

I had to google UHI to work out the acronym (Urban Heat Island effect). I've not heard of Phil Jones, nor of these stories. Quick googling seems to find McIntyre's words on this:

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A couple of years ago, before I got involved in proxy studies, I was interested in the UHI question and wrote to Phil Jones to request the data used in Jones et al 1990, his study purporting to show the unimportance of urban warming. Jones said that it was on a diskette somewhere and too hard to find, Jones observing that the study had been superceded by other studies. (”Moved on” ?) Anyway, that was before I was wise to the ways of the Team and I didn’t pursue the matter.

It really doesn't sound unreasonable to me. Storage technology moves on pretty quickly, and old storage formats quickly become obsolete. I was involved in a recent project to update a data archive, and it took over 2 years to get the data from the old repository into the new one (thousands of gigabytes) - next year, the new repository will be replaced, and the whole exercise will be repeated. 20 years ago this sort of issue wouldn't have been considered, and disks would have collected dust on a shelf till people moved office and had a clearout. Would Jones have expected the detailed scrutiny that his work would undergo decades later?

Steve McIntyre is of course known for spotting one small irrelevant error in one temperature reconstruction, and building it into a vast worldwide conspiracy.

Incidentally, I'm more familiar with David Parker's work that shows the same temperature trend for quiet and windy days (the UHI should be stronger on quiet days). Also as described elsewhere, having reviewed (admittedly at a high level) the temperature stats for the US over the last 112 years, it is pretty clear that this purported Urban Heat Island thing has only really appeared in the last 20 years in the United States - doesn't sound reasonable to me for it to be a UHI.

Steve_M:

Sorry - I assumed you knew UHI.

I think the McIntyre episode is actually more recent than the one you picked up - it arose when he was appointed by the IPCC as a critical reviewer of the work on UHIs. I'll see if I can find anything published on this - I got it from a climate scientist at Birmingham University. Phil Jones, incidentally, is the head of the Climate Research Unit at University of East Anglia, and is one of the IPCC lead authors.

On the UHI itself - it is quite possible that it has only become germane in the more recent past. Just for the sake of argument, because I suspect neither of us is in any position to know, let's assume that weather stations were originally sited outside of towns and cities, but close enough to be easily accessible, and many were built around the same time. (This at least sounds plausible!). If there is then increasing urbanisation (ie the towns and cities are expanding in terms of areas) and at a similar rate, then it is quite conceivable that quite a tranche of the stations move from being rural to being suburban at the same time.

As I say, conjecture, but it doesn't seem to me an obviously silly hypothesis.

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As I say, conjecture, but it doesn't seem to me an obviously silly hypothesis.

I certainly didn't say it was silly. I've seen David Parker in action describing the huge difficulties of keeping a consistent temperature record, which is why I quoted his work.

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Originally posted by Steve_M:

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As I say, conjecture, but it doesn't seem to me an obviously silly hypothesis.

I certainly didn't say it was silly.

Crossed wires time - I didn't mean to imply you thought it; it was merely my assessment of the hypothesis.