climate science
stoat | March 6, 2007*I* don't know. It depends on what you mean. Or perhaps as RP Jr said, "It is a little like saying, would you prefer a poverty rate of 10% or 8%? Well, lower is better, the question is how do you get there? Not by arguing about ideal poverty rates I'd say". Which is a nice way of phrasing it, although there are problems with the analogy.
But the main reason for this post was to pull out of the comments over at inkstain this between Eli and RP:
ER: "Do you believe that any level of GHG CO2 equivalent mixing ratios would be so dangerous/costly as to be avoided through serious mitigation. If so…
stoat | February 27, 2007So says Howat et al. in Science (why hasn't this made it into the blogosphere before? Or did I miss it?). Interestingly, though the most recent change is a decrease: Using satellite-derived surface elevation and velocity data, we find major short-term variations in recent ice discharge and mass-loss at two of Greenland's largest outlet glaciers. Their combined rate of mass-loss doubled in less than a year in 2004 and then decreased in 2006 to near the previous rates, likely due to fast re-equilibration of calving front geometry following retreat. Total mass-loss is a fraction of concurrent…
stoat | February 14, 2007I thought I'd expand a bit more on why Svensmarks figure 4 is unacceptable (fig 4 of arXiv; fig 6 in Cosmoclimatology: a new theory emerges). Bear in mind that there is more wrong in the article than just this, though! The fig is:
I'm arguing about the lower line, which purports to be a 90-64S average. This is sourced to: http://data.giss.nasa.gov/gistemp/tabledata/ZonAnn.Ts+dSST.txt (90-64S zonal mean) and thats a perfectly reputable source. However, not one to be used blindly, as S does. You have to wonder about the data quality. And even a cursory think would lead you to wonder how much…
stoat | February 10, 2007Yes, clouds and cosmic rays are back, via the indefatiguable Svensmark, at arXiv. But excitingly there is an Antarctic twist, in that the clouds connection explains the "Antarctic climate anomaly, ie why Antarctic and rest-of-work are out of sync. Errrm, but are they? Its a common idea during glacial periods, but Svensmark wants it to be true on shorter timescales so that it can't be ocean forcing. See his fig 1. So (ignoring the fact that it clearly doesn break down in the most recent past, which I don't see him noting) there is a nice anti-correlation on longer scales. Which I was unaware…
stoat | February 7, 2007Its probably a measure of how accepted the bulk of the AR4 SPM is, that the most interesting discussion about it seems to center around the sea level rise uncertainty ranges. There does indeed seem to be some confusion here... RP Jr explores this, and points out that it would have been nice had the IPCC made a comparison easier, with which I agree (and complains about the take on this from the most authoritative source, of course RC; though as far as I can see he is wrong to say that we assert that the range isn't lower).
But (before venturing onto the minutiae) I'll say that as far as I can…
stoat | February 5, 2007Tired of AR4? Then read Russ's blog about aircraft instrumentation down at Rothera.
stoat | February 3, 2007Lord Monckton seems to have decided that he is an expert on climate change, and has released his own review of the SPM. Such fun.
He starts: FIGURES in the final draft of the UN's fourth five-year report on climate change show that the previous report, in 2001, had overestimated the human influence on the climate since the Industrial Revolution by at least one-third. Also, the UN, in its 2007 report, has more than halved its high-end best estimate of the rise in sea level by 2100 from 3 feet to just 17 inches.
Interesting if true... but is it true? Oddly enough, no. The first he amplifies as…
stoat | February 2, 2007Call me an old grump but the SPM for the IPCC AR4 report wasn't terribly exciting. Which was, perhaps no great surprise: having read the draft chapters, or at least skimmed them, it was clear that nothing revolutionary was going to appear. They throw in the phrase Warming of the climate system is unequivocal which is a nice sound-bite but was true for the TAR too. Climate sensitivity is likely to be within 2-4.5 oC, but since this is only a 66% statement its quite weak; though they do go on to diss > 4.5 oC a bit. And the attribution key text is:
Most of the observed increase in globally…
stoat | January 28, 2007My saner readers, I'm sure, aren't in the habit of reading Lubos; and indeed neither am I; so we have Ken Brook to thank for drawing Peer-reviewed global cooling to my attention. Its long on words but, oddly enough, rather short on actual quotes from papers doing things like predicting cooling. The best appears to be Multi-scale analysis of global temperature changes and trend of a drop in temperature in the next 20 years.
This paper does indeed say It thus indicates that whether on century scale or on the periods of quasi 60-year oscillations, the global climate wil be cooling down in the…
stoat | January 23, 2007Eli (normally a sensible chap) says: I think a lot of this revolves around the dichotomy between the rise to be observed by date x, the rise committed to (in the sense of there is no way of stopping it) by date y, and the ultimate rise z. There are three different shells and you have to be careful of which one you are turning over. For example, in AIT, Gore is clearly speaking about z.
The distinction is valid. The assertion that Gore is *clearly* speaking about z is nonsense. For several reasons. Most trivial, there is no reason why 5 or 6m would be the ultimate rise. But more importantly,…
stoat | January 17, 2007I'm getting a bit annoyed with people pushing over-inflated estimates of SRL in the near future. Richard Alley apparently said There is no consensus on how much Greenland's ice will melt in the near future, Dr. Alley said, and no computer model that can accurately predict the future of the ice sheet. Yet given the acceleration of tidewater-glacier melting, a sea-level rise of a foot or two in the coming decades is entirely possible, he said (though in his defence its not in literal quotes).
But the current rate is 3 mm/yr. If that doubles to 6 mm/yr, then over two decades that would be 120 mm…
stoat | December 18, 2006RP Sr has yet another post The Relevance of Nonlinear Effects In the Climate System pushing the usual stuff: Thus if we accept that small perturbations can result in significant changes in the climate system through nonlinear interactions, then all of the human- and natural climate forcings need to be assessed in this context. I would sigh and move on (I did, earlier today) but now I feel moved to find an old post of mine: Climate is stable in the absence of external perturbation. See, its so old its on the old blog...
Anyway, the point is that people vastly overplay the importance of this…
stoat | December 13, 2006I was at the NCAS conference today (since it was in Cambridge it would have been impolite not to go). Tim "Da Man" Palmer spoke about, ermm, sort of a merge of NWP and climate scales. But thats not the point... the point is that he showed a stratification of the Staniforth CP.net PDF in terms of modifications to the entrainment scheme. Increasing entraiment, or leaving it unchanged, produced the low values (up to 6). All the high sensitivities (6-12) came from experiments in which the convective entraiment was reduced (also, although he didn't mention this, all the high sensitivies had a…
stoat | December 10, 2006Having had a couple of comments on this, I realise that some of the required background on Bayesian statistics is waaaay over some peoples heads. This is probably no fault of theirs. Let me make some faint attempt at explanation, and James can correct me as needed, and doubtless Lubos will leap in if I leave him an opening.
The issue (at least in this context) is the updating of "prior" information in the light of new information. Prior information means (at least nominally) what you knew about, let us say, the climate sensitivity S before you tried to make any plausible estimates of it. If…
stoat | December 7, 2006This post is just to get you to read James Annans post about: An Inconvenient Truth. Which is his (& Jules) attempt to get his paper about climate sensitivity published. Since the paper is sound, and sensible, and very clear and readable, and of clear wide interest, the question is why isn't it published?
The best available answer seems to be that some people don't like his rather clear demonstration that a lot of the talk about high climate sensitivity (hands up CP.net and Stern) is nonsense.
Another possibility is that he isn't well known enough: this is the sort of basic paper that…
stoat | December 5, 2006I've listed a few of Moncktons mistakes in previous posts; and RC has a nice article about his misunderstanding climate sensitivity.
Adam points out in a comment that Monbiot is now saying (in the comments) ...what happened to the debate with Christopher Monckton. A good question. So far my attempts to challenge him have been met with threats to sue for libel. While the Guardian can cope with this, I'm in a more exposed position when posting material on my own sites. This is why I have not yet posted my original article about his paper on monbiot.com, let alone any rejoinders. Which is…
stoat | November 30, 2006The "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.
stoat | November 30, 2006Climate 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…
stoat | November 28, 2006From 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.…
stoat | November 27, 2006The 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 http://www.wmo.int/web/arep/gaw/ghg/ghg-…