Methane from Dams

The “dams produce lots of methane” arguement has come up again, in Nature (subs req): In the specific case of Balbina, there is now a rough consensus: in terms of avoiding greenhouse-gas emissions, a fossil-fuel plant
would have been better
. Balbina is a dam in Brazil. Opinions seem to vary on just how much methane it emits from decay of vegetable matter, with (oh dear) people partly funded by the hydro industry getting somewhat lower numbers. But the data appear to be sparse… a clear case for more monitoring.

Climate change sceptics lose vital argument

Climate change sceptics lose vital argument says the New Scientist. This is a novel twist on a paper in Nature: Gulf Stream density structure and transport during the past millennium; David C. Lund, Jean Lynch-Stieglitz and William B. Curry; doi:10.1038/nature05277. The editor says of it: an analysis of sediment cores from the Florida Straits, where the Gulf Stream enters the North Atlantic, has been used to reconstruct a record of the past 1,000 years. The results suggest that the Gulf Stream was weakened during the Little Ice Age (AD 1200-1850), a time of unusually cold conditions in the North Atlantic region, particularly Europe, implying that changes in Atlantic Ocean circulation had an impact on climate during historical times.

NS asserts that this may explain why MBH (aka the Hockey Stick) doesn’t show the Little Ice Age, since it makes it a regional phenomenon. Um? the cooling that resulted was confined mainly to the northern hemisphere, says Lynch-Stieglitz – which indicates it was a regional effect. Michael Mann at Pennsylvania State University in University Park, who constructed the hockey stick graph, has always argued that if this were so, the little ice age would not show up on a global temperature record. This is odd: MBH has only for the NH anyway… The idea that the LIA was regional and/or more of a redistribution is a standard one; its not really clear how this result adds anything to it. I suspect this is NS getting somewhat carried away.

More Monckton

There is a fun wiki user page collecting a rebuttal of Moncktons nonsense. Mostly I’m impressed by peoples patience in bothering to follow it all through. One thing sticks out to me: Moncktons apparent use of references that totally fail to support his claims for them. For example, Monckton says “From c.1000 AD, ships were recorded as having sailed in parts of the Arctic where there is a permanent ice-pack now (Thompson et al. 2000; Briffa 2000; Lamb 1972a,b; Villalba 1990, 1994).” but apparently T2000 is concerned with hydrology on the Tibetan plateau; B2000 is, as you might expect, a general review of analysis of tree-ring proxy data for reconstructing past climate; Villalba lends no support. So where did M find these things? Did he totally make them up? Copy from elsewhere without checking? Or just fail to understand what he was reading?

Science: False Alarm: Atlantic Conveyor Belt Hasn’t Slowed Down After All

From Science 17 November 2006: Vol. 314. no. 5802, p. 1064 DOI: 10.1126/science.314.5802.1064a: A closer look at the Atlantic Ocean’s currents has confirmed what many oceanographers suspected all along: There’s no sign that the ocean’s heat-laden “conveyor” is slowing. The lag reported late last year was a mere flicker in a system prone to natural slowdowns and speedups. Furthermore, researchers are finding that even if global warming were slowing the conveyor and reducing the supply of warmth to high latitudes, it would be decades before the change would be noticeable above the noise.

Nothing new there, then.

Carbon emissions show sharp rise?

The BBC reports The Global Carbon Project says that emissions were rising by less than 1% annually up to the year 2000, but are now rising at 2.5% per year. And then provides various reasons why this is so, including a switch from oil to charcoal as oil prices rise (is this plausible, on the large scale?). Sounds worrying. But…

a graph I drew earlier shows CO2 in the atmosphere rising at about 2 ppmv/y, though with wiggles, over the last few years. So I’m not sure how to reconcile that with the recent-increases stuff.

[Addendum: M points out that shows much the same pics as mine (good). It doesn;t say much about emissions, but does comment that the airbourne fraction is still about 55%]

Nordhaus on Stern

Via Prometheus, I find a review of Stern by Nordhaus. First an aside: N is the first mainstream commentator I’ve seen to point out that the Great War on Terror was undertaken “with no discernible economic analysis”… as I’ve pointed out, both Lomborgs “Consensus” and Pielkes recent re-run have shied away from considering the economics of said War.

N points out what others have: that Sterns results are dramatically different from earlier economic models that use the same basic data and analytical structure. N does what S should have done: point out why this difference exists.
Continue reading “Nordhaus on Stern”

Brief Holiday

We had a brief holiday on the Norfolk coast this weekend; and were lucky to have two days of near-perfect weather. Or at least blue skies – it was still pretty cold and somewhat blowy. Here you see our shadows marching off into the distance.

Castle Rising was good, too. The first time I’ve ever been there. Its a very odd Castle – it was a genuine one, not just for show, and yet its elaborately decorated on the outside. The photo of M in the arched passageway is interesting: the passageway was cut through the thick wall because the floor of the main hall had collapsed and they had no other way to get to the far end. Other than rebuild the floor, of course, but that doesn’t seem to have occurred to them.

Apologies to those whose comments got queued in the meantime. Regular service is now resumed.

Draft AMS statement on climate change

The AMS has a Draft statement on climate change, vn 7.0. I found it via RP Sr, who dislikes it, for the obvious reasons: it fails to reflect his hobbyhorses: which are, as ever, downplaying the role of CO2 in favour of land-use changes, aerosols, etc (of course it does mention them, but naturally enough after GHGs). I find his “I reproduce a summary below of findings that have been reached on the weblog Climate Science ( ) which should be discussed in the AMS Statement.” quite shameless self-promotion. It will be interesting to see if the AMS is convinced. I am prepared to agree that the linking to weather predictions models isn’t quite as strong as they imply, but thats just trivia.

OTOH there are some oddnesses: “In the last fifty years atmospheric CO2 concentration has been increasing at a rate much faster than any rates observed in the geological record for several thousand years.” Geological record? They mean ice cores. And several thousand? They mean hundred thousand. Unless they think the glacial termination changes are comparable, but I don’t think they are.

And in the sea level section: “Moreover, ice sheet modeling and paleoclimatic observations indicate that the melting of the Greenland Ice Sheet will likely cause global sea level to rise meters if warming continues at its present rate through the 21st century.” This too seems odd… the last I saw, Greenlands contribution over the next 100y is much less than a meter. Or… is that a carefully constructed true-but-misleading statement? It can, just about, be read as Greenland will cause meters of SLR, at some point in the far future, if T increases through this century. And that version would be true.