Smn mst cm p wth sltn tht msrs cycls bgnnng wth th lst tw c gs, r hwvr mny w hd, nd t msr th 'ht' vllys btwn th c gs. Msrng snc 1979 prdcs crp dt, n sns, bt sfl n tht w cn nw pln fr crs thrgh th Nrthwst Pssg, nd t sll prprty n th Glf Cst.
Th bv s nt rckt scnc. ls, f rcll, th lctr-mgntc shld, n thry, cld hv sm brng, n tht n thrst, fw yrs g, r dcds g, cn't rmmbr whch, ntrdcd dt tht sggstd tht th pls swp plrty jst prr t th nxt c g. cn't ttlly rcll th bv, s pls chck ths hypthss.
[Editor: ignore=off]In Alexander Cockburn's article Is Global Warming a Sin? he writes that "There is still zero empirical evidence that anthropogenic production of carbon dioxide is making any measurable contribution to the world's present warming trend."
Cockburn bases this on the work of Martin Hertzberg who believes that water vapor is a much stronger atmospheric agent, by far, than CO2.
Any comment?
Posted by Don Bacon at May 4, 2007 09:18 AMThe long cycles between a glaciated and largely deglacited planet (the largest change in the norhtern hemisphere) are related to changes in Earth's orbit around the sun. I've written about that right here at The Left Coaster, give it a read. We have a variety of paleoclimate proxy data over the Cenozoic, the last 65 million years and even more over the Quaternary, the last 1.8 million years. There are many great resources available via the internet for those who are interested. A good place to start is NOAA's paleoclimate website.
I have no idea what "crap data" means so I'm not sure how to respond. One point that might be useful is that we have enough years of satellite data to be able to get at the difference between "natural" variability and an externally driven trend. There are additional observations going back farther in time but they lack the spatial and temporal resolution of the satellite observations since 1979. We can also examine corroborative data that suggest the pronounced decline in Arctic sea ice is something new since the post-glacial climate optimum (orbitally-driven) between 8,000 and 6,000 years ago.
Posted by Christina at May 4, 2007 09:22 AMscout's an uninformed troll that thinks the earth is only 13K years old. Best to ignore him.
Posted by iamcoyote at May 4, 2007 09:55 AManthropogenic production of carbon dioxide...measurable contribution
The role of gasses such as CO2, CH4, NO2, and H2O in warming Earth's atmosphere has been understood since the 19th Century. H2O is more complicated than the others because it can have both warming and cooling effects. H2O content in the atmosphere varies between about 1% and 4% just due to day-to-day and seasonal variability. Here's a movie of atmospheric moisture. Here's a 1995 report on water vapor in the climate system from the American Geophysical Union. A fantastic history of global warming studies is available here.
The rapidity of the recent global mean warming does, in fact, stand out from the variability of the last two thousand years. The magnitude is exceptional over at least the last 1400. Read more in an oft-misquoted National Academy of Sciences report here.
As to attribution, quoting myself:
The connection between anthropogenic greenhouse gas emissions and global warming was established preliminarily in Intergovernmental Panel on Climate Change's Third Assessment Report (TAR). It was shown there that models driven by natural variability only and anthropogenic forcings only could not reproduce observed global temperature trends from 1850 to 2000 but that models including both could. The AR4 supports that conclusion more firmly than did the TAR.
Posted by Christina at May 4, 2007 09:56 AM
Should be "forecast".
The acceleration of warming seems to correlate with the much improved removal of particulate from the atmosphere which began in the early 60's. The particulate had been offsetting the effect of the increased levels of CO2. Also the greater use of jet engines helped accelerate warming. These are my observations.
Posted by JohnT at May 4, 2007 10:07 AMhttp://realclimate.org/
Also covers the Cockburn article.
Posted by anony at May 4, 2007 10:15 AMThe acceleration of warming seems to correlate with the much improved removal of particulate from the atmosphere which began in the early 60's. The particulate had been offsetting the effect of the increased levels of CO2. Also the greater use of jet engines helped accelerate warming. These are my observations.
Ever think to test your theories? Or just spout them out there like they are facts.
I'm forever dismayed that people imagine that they can, with only a few moments thought and a bit of light reading, understand an incredibly complex topic better than the thousands of intelligent people who have devoted their life's work to that topic.
I said these are my observations. I don't pretend to know as much as anony and the other experts. If you don't engage you don't learn anything.
Posted by JohnT at May 4, 2007 10:35 AMsht p jckl, Chrs hs brn, nd knws hw t s t wtht gttng ll frky-mtnl.
Chrs, by wk dt, prps tht th dt gthrng by whtvr mns, snc 1979, s nt sfl n spprtng th fls ntn tht glbl wrmng s mn md, ncssrly.
Th lst c g ws prbbly bt 12k yrs g, nd d nt tht mny spclt th bv nywhr frm 20k t 70k yrs g. Bt ths fgrs r t lng.
Dndrlgy, f t cld b shwn tht tr rngs r clsr drng tms f drght, nd frthr prt drng tms f wt/cl, cld b sfl, vn fsslzd trs wld wrk. My hypthss wld b tht w hv 5k wrmng/clng cycl tht pks vry 12k yrs nt clng, wth htng n th mddl.
ny mn md wrmng wld b nsgnfcnt, nlss smn cld fctr n rdctv xplsns/lngsd th ffcts f rdctv wst, ncldng th sgs f DP. Th hypthss wld ncld vrbl spprtng lnk btwn rdctvty nd wrmng, whch s prbbl.
Th bv wld mk sns, ls, Bblclly n tht dstrctv mn, lwys n rblln, skng dth f thrs nd hmslf, wld sly dd t hs wn dms n th nm f pwr vr thrs wth th nvntn nd sg f wpns f mss dstrctn nd t's blwbck pn mn n gnrl.
Ths cld b n xcllnt cntr t ths tht spprt WMD's. S, by tyng glbl wrmng t WMD, w hv ppld lvrg t th pltcl gngstrs f r tm.
ls, yr 'rght hr' lnk ddn't sm t wrk, s f y cvrd ny f th bv, t ws ndpndnt.
[Editor: ignore=off]The last ice age was probably about 12k years ago, and I do note that many speculate the above anywhere from 20k to 70k years ago. But these figures are too long.
Perhaps you are thinking of the Younger Dryas, an abrupt return to cool conditions, especially in the northern hemisphere, after deglaciation was well underway. The exact timing of the last maximum ice extent varies a bit regionally due to the effects of large ice sheets on atmospheric circulation but in general was about 18,000 years ago and the peak of the last interglacial was about 125,000 years ago. This is well known and well studied though new details are emerging all the time. Geologists and paleoclimatologists have been investigating these things since the Age of Enlightenment. Nobody working in the field professionally speculates that the last glacial maximum was 70,000 years ago.
The standard chronology used across the disciplines comes from deep sea oxygen isotope ratios (which are a proxy for the transfer of water from the ocean to glacier ice and back again).
My hypothesis would be that we have a 5k warming/cooling cycle that peaks every 12k years into cooling, with heating in the middle.
This is not what's observed. There are many resources available for reading up on this, maybe the link to my earlier post on long-time-scale climate cycles is a place to start. Sorry for the broken link, here is the correct one.
Posted by Christina at May 4, 2007 12:01 PMTh prblm wth ny frm f xygn stp rt dt s tht thy r nrlbl d t ncrrct ssmptns cnnctng cld t ncrsd x stp. Hr s n st shwng th bv:
http://thms.wb.wslyn.d/s123/plxs.htm
scrll dwn cpl pgs, scnnng s y g, nd y nt tht ny frm f xygn stp cmprsns smply d nt stnd p t shw thrtcl glbl wrmng, r nythng ls, fr tht mttr, thr thn nsgnfcnt cmprsns btwn vpr, c, nd wtr.
ssmptns r tgh t dl wth, nd tht s why w nd tchrs, scntfc, tht nt nly ndrstnd th dffclts f thry, bt ls ndrstnd Khn's pnts f th mnd st f prdgm thnkng, nd hw prdgm shfts slwly hppn, nt tht shfts prdc ny trth whtsvr, n thmslvs.
[Editor: ignore=off]hy, trd th lnk, bt t ddn't wrk gn. Pls chck t whn y gt chnc, s wll fllw thgh n th ld. t my b pssbl tht t s n f my kky srvrs, s 'm gng thrgh fw t pst.
[Editor: ignore=off]So how do the two better performing models handle the sea ice component in a way that end up fitting the observations better?
Posted by euzoius at May 4, 2007 01:19 PMhttp://ethomas.web.wesleyan.edu/ees123/paleoxiso.htm
The (technical) discussion at this site in no way disputes anything I wrote about the use of oxygen isotopes. Not sure what scout thought I wrote, we don't seem to be communicating very well.
Here's the link I've tried twice (not sure what's up with that) as text.
www.theleftcoaster.com/archives/009823.php
Posted by Christina at May 4, 2007 02:03 PMChristina, I was just thinking the same thing; I couldn't find what scout was trying to say, other than he was hoping to trip you up with what he views as mumbo-jumbo. As he's stated, he's a young Earth adherent. He does have a history of statements about the inferiority of women, especially those in positions of authority, so I would suspect he's trying to assert his superiority over you by pretending to understand the science. He's been banned several times but refuses to stay away. Sorry for the disruptions!
Posted by iamcoyote at May 4, 2007 02:17 PMscout, I have absolutely no idea why any ISP would let you use their server. You are such an idiot. You are stupider than I am. And that is saying something.
Posted by tempus at May 4, 2007 02:19 PMTh st stts, n th scnd r thrd prgrph, nd ltr n, tht th crb xy stp mthd s nrmlly sd t msr plr c vlm, nt ncssrly tmp chngs vr tm, lthgh th lttr hs bn frcd d t th bv mntnd ssmptns.
Frthr, w nt th ssmptns f th stp tst n tht t rls pn lf: 'W cn s ths mthd t fnd th tmprtr t whch th clct ws prcpttd nly F w knw th stpc cmpstn f th wtr frm whch th clct ws prcpttd. n ddtn, clct n ntr s nt prcpttd frm wtr smply by chmcl rctn: th chmcl rctn ccrs wthn th bds f rgnsms. Fr mch plcngrphc wrk vrs spcs f plnktnc (fltng n th wtr clmn) nd bnthc (lvng n th s flr) frmnfr (nclllr rgnsms wth clct shll) r sd; th cmbntn f dt n plnktnc nd bnthc spcs llws dtrmntn f tmprtrs n srfc nd dp wtrs.'
s ny cngrphr knws, th wrld's cns r nythng bt sttc, bt rvrs nd cnstnt pwllng, tht wld cnfnd th xy mthd t ll bt th mst stbbrn mnd.
Th mthd s nrlbl, bt ds crt gd jrnl fllrs.
[Editor: ignore=off]chrs, dn't py ny ttntn t jckl nd hr thr mnkr, th cntmpts. Sh s bvsly lt ldr thn y nd hs tlvd hr sflnss:) Dmnt s hr nly str, ths dys.
[Editor: ignore=off]So how do the two better performing models handle the sea ice component in a way that end up fitting the observations better?
The big thing is that they deal with sub-grid scale variations in ice thickness. This is important for getting the heat flow between ocean and atmosphere right and also has an influce on how various sea ice related feedbacks play out in the model and on ocean water density (which matters for ocean circulation).
One of the models is CCSM3.0 (Community Climate System Model), developed at the National Center for Atmospheric Research in Boulder, CO. The other one is the Hadley Center's (UK Met Office) HadGEM1.
Here's the abstract of a paper by Marika Holland and others in the Journal of Climate on this topic (Influence of the Sea Ice Thickness Distribution on Polar Climate in CCSM3, J. Climate, v19(11), 2006). Google the paper's title and you'll find an online pdf of the whole thing, I'm sure.
Posted by Christina at May 4, 2007 02:36 PMGreat links, Christina, thanks! Light reading for the weekend...
Posted by iamcoyote at May 4, 2007 03:04 PMIamcoyote, you were right. He doesn't even know when to be embarrassed, but arrogance will do that. (see George Bush)
Posted by Judith at May 4, 2007 03:13 PMChristina, this is driving me nuts. I read a paper on carbon sinks, and the gist was there a "product" or some new process that extracts carbon that is then tilled into the soil, enriching the soil and ameliorating atmospheric carbon. I'll be damned if I can remember the name of the process... aginprex...agorp.. something like that.
So, would you know the researcher(s)and name of this process? Are carbon sinks a rational alternative to other methods of limiting carbon pollution...and, when at a dinner party, do I greet the guest on my left first, or the guest on my right (hey, I'll take my etiquette any place I can get it)? I'm teasing about the last one...maybe.
Posted by phidipides at May 4, 2007 10:34 PMThanks for making clear the distinction between "faster than expected" sea ice retreat, and what we might call "faster than the models can simulate."
This raises a question: How long does it take to revise and rethink a model and run it again?
To put it in practical terms, could we expect to read at this time next year that a new iteration had successfully modeled the retreat of Arctic sea ice?
Posted by Kit Stolz at May 5, 2007 11:42 AMHow long does it take to revise and rethink a model and run it again?
Excellent question. The answer depends on the nature of the change to be made (how complicated is it to implement?) the nature of the lab working on the model (how efficient is their organization?), and whether or not we really understand the change that needs to be made. A reasonable time frame for significant change to an individual componenet in a model is something on the order of a year.
Will all of the models have "better" sea ice a year from now? It's hard to say because the modeling groups have many issues on their agendas as they move forward from the IPCC Fourth Assesment.
Coupled climate system models, as you might expect, are big. Building and operating them requires teams of people all with fairly specific functions, such as theory for the various model components, numerical implementation of that theory, software design, work flow management, and so on. You can get a feel for what this is like by having a peek at the National Center for Atmospheric Research's CCSM homepage. The CCSM online brochure gives a nice overview for a general audience.
Posted by Christina at May 5, 2007 12:13 PMsoil carbon sequestration
I don't know a lot about this. Everything I've read has been about tilling organic material back into the soil (conservation tillage). The USDA supports research in this realm, along with changes in non-agricultural soils.
Conservation tillage can play a role in stabilizing atmospheric CO2 content. The Carbon Mitigation Initiative folks at Princeton has evaluated this in their "carbon wedge" framework. Here's a chart with links to their analysis.
Folks I know who think about these things tend to view mitigation as what you do to give you time to work out adaptation strategies. The reality is that we are in for significant climate change due to the the fossil carbon we have already put into the atmosphere (an earlier post on this). It seems to me (and colleagues who work in the science & planning field back this up) that while U.S. state governments are starting to pay attention to mitigation, little attention is being paid to adaptation. This is, in my opinion, a problem.
Posted by Christina at May 5, 2007 12:58 PM