Sunday, January 31, 2010

Carbon dioxide feedback.

The recent paper in Nature of Frank et al on CO2 feedback has had a run in the blogosphere. That was started by a review in Science Daily. Briefly, the paper says that the minor feedback mechanism by which warming causes CO2 to be expelled from the oceans, causing more warming, is less than some recent estimates. The key figure is the increase of CO2 in ppmv resulting from 1C warming, and Frank et al give a median figure of 7.7, with a range from 1.7 to 21.4.

That's actually a pretty wide range. But does it refute any sort of consensus? I looked up what the AR4 had to say. There wasn't much, but in Chap 7, sec, I found this:
“A 1°C increase in sea surface temperature produces an increase in pCO2 of 6.9 to 10.2 ppm after 100 to 1,000 years (Heinze et al., 2003; see also Broecker and Peng, 1986; Plattner et al., 2001). “

That seems quite within the range Frank et al find. Yet people who suggest some pillar of AGW has fallen say that recent estimates were up to 40 ppmv/C. Lubos Motl had cited that figure, so I put the IPCC figure to him. He cited this 2006 paper by Scheffer, Brovkin and Cox as the source of the 40 ppmv/C claim.

I looked up that paper. They had deduced their estimate from the CO2 response to the LIA, and said
we arrive at an estimated carbon sensitivity (α) to temperature of 41 (following  Mann and Jones) to 12 (following Moberg et al) ppmv CO2°C.

A rather ambivalent figure to be refuting.

Thursday, January 28, 2010

GHCN Stations warming?

Update Fri Jan 29 2.56 pm (East Aust Time) Big Oops. Programming error.

It is surprising that such a simple program could have a programming error. But there was a memory overflow, and it had a big effect on the results.

With that corrected, there is indeed a rise in station mean temps. The new graph is here. I should emphasise that the plot is of "naive" means - just averaging all readings for each year, including duplicates.

The new plot is like that on p 14 of the d'Aleo/Watts report, and different from that on p 11.

The revised R code I used to calculate and plot this example is here

Earlier post:

The new report of d'Aleo and Watts, trumpeting calculations of E.M.Smith, makes much of a supposed shift of GHCN stations to warmer areas as an alleged source of warming. Indeed, it is full of accusations that this is done with fraudulent intent.

Of course, anomaly calculations wouldn't show warming for that reason. But is the station set actually warming?

I did a simple calculation. Just the average temperature of all stations in the GHCN set v2.mean, for any year. You might expect a small rise reflecting global warming. But if there is nett movement of stations to warmer climes, that should show as a bigger effect.

Here's the result, plotted from 1950. The trend is actually down.

The R code I used to calculate and plot this example is here

Update 29 Jan. I investigated the downspike about 2006. It's caused by some stations returning a lot of missing months, which yields erratic results. So I put a screen in the program requiring at least 9 months of data before a station could contribute to the year's average. It didn't change the overall picture, but did eliminate the spike at 2006.

Following a suggestion of Carrot Eater, I checked the v2.mean adjusted file. The results, not very different, are here .

Saturday, January 23, 2010

GHCN Station selection.

WUWT has featured Marc Sheppard's American Thinker article, which gives a prominent place to E.M.Smith's claims about how GHCN has been selectively dropping cool stations to boost apparent global warming. I was going to blog extensively on this, but I see that Real Climate. and more completely Zeke Hausfather have it well covered. However, maybe there's a bit to add to the WUWT discussion.

Wednesday, January 6, 2010

What if there were no Greenhouse Effect?

Roy Spencer recently put up a post on his blog, reposted at WUWT, on the old chestnut of "What would the world be like without the greenhouse effect?". His thesis: "there would be no weather on Earth without the greenhouse effect." That, and some other things he wrote, are wrong.

But first, let's look at how "no GH effect" could be implemented. The simplest way is just to imagine that the Earth had the same gas constituents, but somehow they magically lost their ability to absorb and emit thermal IR. Roy S goes further, saying:
"So, let’s imagine an extremely cold Earth and atmosphere, without any water vapor, carbon dioxide, methane or any other greenhouse gases – and with no surface water to evaporate and create atmospheric water vapor, either."
That's a big change, but let's go with that.