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MThompson at 06:33 AM on 4 September 2013Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
tcflood @89
So if I understand correctly, the CO2 bending mode is continuously populated by the earth's blackbody radiation in the range of 13-18 microns (770 to 560 cm-1) plus, to a lesser extent, collisions with other atmospheric gasses that have sufficient kinetic energy to activate the bending mode. Of course the most probable speed of the atmospheric gasses does not have enough energy to excite the bending mode, but some small number of atmospheric gas molecules do because of the Maxwell-Boltzmann tail.
Once the CO2 bending mode is activated (by either mechanism) it will relax primarily through collisions with N2, O2 and Ar, thus raising their kinetic energy. The probability of CO2* emitting a photon in the range of 13-18 microns (770 to 560 cm-1) is very small because of the high collision frequency of atmospheric air molecules in the troposphere.
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CBDunkerson at 05:21 AM on 4 September 2013Study offers clues on 20th century global warming wobbles
K.a.r.S.t.e.N, I agree that one paper doesn't change things, but I have been seeing a lot of papers pushing ocean cycles lately and nothing on aerosols for quite some time. Hence my perception of a shift in the balance of thought on the subject. It is possible that the shift has just been in the papers I have happened to encounter, but that would be a rather odd series of coincidences.
On cloud feedbacks... it wouldn't surprise me if aerosols play a greater role there than ocean cycles, but the general trend of the research I've seen has suggested that cloud feedbacks are likely small (unless that too is an incomplete picture).
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K.a.r.S.t.e.N at 03:39 AM on 4 September 2013Study offers clues on 20th century global warming wobbles
@CBDunkerson:
I'm afraid I have to disagree ;). While this paper is a promising attempt to narrow down the attributable temperature range (of individual forcers/internal variability), I would be cautious to draw definite conclusion regarding the total aerosol effect. Their proposed direct DTR-solar radiation link works well if only one forcing agent is involved, but other forcing agents do contribute as well, particularly when it comes to cloud feedbacks. Aerosols are certainly the major player, but the results are far from robust enough to overturn the huge amount of literature which points to stronger aerosol effcts. In fact, the "ocean cycle school" has been considerably challenged in recent years by the "external forcing school". One paper won't change that trend ;)
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K.a.r.S.t.e.N at 02:52 AM on 4 September 2013The Pacific Ocean fills in another piece of the global warming puzzle, and puzzles Curry
@Kevin C:
While TCR is indeed a bit lower (1.4K), the current warming seems to be slightly underestimated which leaves wiggle room for upward adjustments. So not much of a difference. The problem I see with the GISS forcing is that it can't be reconciled with the sulfate emission inventories at all. As sulfate aerosols are the most efficient cooling agent, a linear (negative) aerosol forcing ramp up appears extremely unlikely. Apart from Skeie et al. 2011, also Meinshausen et al. 2011 and Forster et al. 2013 seem to confirm this point of view. The fact that it reduces the correlation coefficient in the 2-box model is an interesting one, but nothing to be worried about. Plenty of options as to why that's the case. I might elaborate on that at the next opportunity (it's primarily a response time issue).
Just to make sure: What you refer to as "Potsdam forcing" is based on Meinshausen et al. 2011, or did I get that wrong? I guess, the Forster et al. 2013 forcing wouldn't actually be that much different. I am not aware of a readily accessible source for the forcing data. Apart from Piers, you may contact Alexander Otto (he used to work from home, so I can't ask him directly).
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Chris G at 01:50 AM on 4 September 2013The Pacific Ocean fills in another piece of the global warming puzzle, and puzzles Curry
My guess is that Curry got too close to something that made her "terrified beyond the capacity for rational thought", probably at a subconscious level. She has a pattern of invoking the half of uncertainty that does not go there, or only seeing the half of the cycle that takes her farther from there. The simplest explanation I can think of for her illogical thinking is a subconscious filter on what she is able to incorporate into her world model.
No, I'm not a clinical psychologist; yes, I have a degree in the field. I know about enough to get myself into trouble. It fits what I learned in school, but I'm not qualified to do more than guess. -
One Planet Only Forever at 00:22 AM on 4 September 2013The Pacific Ocean fills in another piece of the global warming puzzle, and puzzles Curry
The discussion or presentation of average global surface temperature in terms of "decadal" values may not be the most effective way of communicating the issue. "Decade-by-decade" presentations can play into the scams of those wanting to "delay” action that would reduce their ability to get more profit, pleasure, comfort, or convenience from burning fossil fuels (a practice that is not only creating costs future generations will face without having benefited from the burning but that is simply not sustainable by future generations because the fossil fuels become harder and harder to obtain and eventually would run-out).
“Scientific denial” is not the real problem. The real problem is the success of political efforts to “delay” popular support for actions that would limit the ability of people to get benefits from burning fossil fuels. Those efforts can continue to succeed by arguing that we need to wait for more proof. Claiming that 2000-2010 was the warmest decade to date only allows them to argue that though that may be the case the temperatures so far since 2010 are not higher so we need to wait until after 2020 before we can know more about the need to “start debating” how to reduce the burning of fossil fuels. And a person tending to want more personal benefit will easily consider that to be a reasonable claim, to delay the action that would reduce their potential for benefit.
Presenting the likely magnitude of variability of global average surface temperature due to the ENSO cycle along with the level of the ENSO at the time of a global average would reduce the ability to claim the “need to wait for more proof”. Another way to argue with the delayers would be to point out that until an El Nino event occurs that is as significant as the 1997-98 event they can make no claim regarding “any slowing or stopping that appears to have occurred since the last major El Nino”.
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Kevin C at 23:48 PM on 3 September 2013The Pacific Ocean fills in another piece of the global warming puzzle, and puzzles Curry
K.a.r.S.t.e.N: That's interesting. The lower aerosol indirect contribution supports a slightly lower TCR, and leaves a little room for a long period oscillation such as the PDO.
Do you know if Piers Forster's forcings from the Otto et al paper are available? I'd like to compare them as well if possible, as it might shed some light on the different TCR estimates we are seeing at the moment.
(If not I guess I'll write to him) -
CBDunkerson at 22:07 PM on 3 September 2013The Pacific Ocean fills in another piece of the global warming puzzle, and puzzles Curry
"Curry incorrectly argued that the study supports the position that global warming is mostly natural."
At a certain point it becomes difficult to believe that deniers are deluded enough to really mean the things they say.
The model incorporates warming from greenhouse gases. It finds that, to date, the overall impact of natural variations has been to mute the atmospheric warming from greenhouse gases by a very small amount. That directly contradicts the position Curry is taking. Or to quote the abstract;
"Although similar decadal hiatus events may occur in the future, the multi-decadal warming trend is very likely to continue with greenhouse gas increase."
How can Curry not know that her stated position on this is nonsense? It's like watching a video from space of the Earth spinning through the course of the day and then saying, 'This supports my position that the Earth is flat.' No... it really really doesn't, and anyone with even basic reading comprehension and reasoning skills can see that. So... what the hell?
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K.a.r.S.t.e.N at 21:57 PM on 3 September 2013The Pacific Ocean fills in another piece of the global warming puzzle, and puzzles Curry
@Kevin C:
While the Potsdam forcing might exclude the 2nd AIE (cloud lifetime effect), there is no strong evidence that it really matters. The Potsdam-AIE with default weighting corresponds almost perfectly with the current best estimate of the total AIE. What keeps puzzling me is why GISS assumes this rather constant aerosol forcing ramp up. That's very unlikely to be the case (see Skeie et al. 2011). I therefore strongly recommend to use the Potsdam forcing.
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CBDunkerson at 21:38 PM on 3 September 2013Study offers clues on 20th century global warming wobbles
Seems like there is a growing consensus for ocean cycles being the dominant factor in atmospheric warming "wobbles" rather than aerosols or (even further out of the running) solar variation. What's ironic is that the same deniers who long insisted that global warming itself was simply the result of these ocean cycles now refuse to believe that they could possibly be responsible for decreased atmospheric warming.
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JasonB at 20:47 PM on 3 September 2013Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
spoonieduck,
As Michael suggested, you should identify the appropriate thread for each of your varied comments so that they can be addressed individually in the correct place. For your questions about Consensus, for example, you could go to the top-left of the page, where the thermometer graphic lies under the heading "MOST USED Climate Myths and what the science really says...", and you'll see that number 4 is "There is no consensus". Click on that link and it will take you to a post with Basic, Intermediate, and Advanced levels that answer your questions before you even asked them.
For the question about whether it was a lot warmer in the far North "way back then", you could start with number 1, "Climate's changed before", and learn how it's precisely that which helps us predict what the consequences will be this time. (Note that being warmer "hundreds of thousands of years ago" is not inconsistent with it being warmer now than since the last interglacial.) You might also want to read the series of posts starting with The Last Interglacial - An Analogue for the Future?
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michael sweet at 20:09 PM on 3 September 2013Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
Spoonie,
At this site we like people to post on topic to the thread. Since you have so many points you are off topic on most threads. Pick the one ot two you feel most strongly about and ask about that.
I noticed your high school math teacher was way off base. The atmosphere is currently 400 ppm CO2 and went up 3 ppm last year. That is about a 1% per year increase at current rates of emission. About half the emitted CO2 is absorbed so about 2% per year is emitted. There are several hundred years of supply at current rates of emission. You are off by about a factor of 1,000,000. I suspect the rest of your information is about as current as your CO2 emissions. Ask questions about what you do not understand and people will try to help you. If you get your information from the denier blogs you will stay a million times off.
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michael sweet at 19:55 PM on 3 September 2013The Pacific Ocean fills in another piece of the global warming puzzle, and puzzles Curry
Tamino has a post on this article wit ha little more technical detail.
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Matt Fitzpatrick at 17:29 PM on 3 September 2013The Pacific Ocean fills in another piece of the global warming puzzle, and puzzles Curry
Yeah, there's quote mine gold here. I'm surprised "... the decrease in tropical Pacific sea surface temperature has lowered the global temperature by about 0.15 degrees Celsius compared to the 1990s" hasn't gotten ripped out of context and reposted on a bazillion blogs. Yet.
But as to the substance of the paper, climate contrarian Marcel Crok asked Xie for a response to Curry's analysis, which is now posted on Crok's blog "Staat van het Klimaat", which appears to be Dutch for "Look How Cold It Is!".
Short version, Xie agrees with Curry that recent warming was modulated by natural variability, but cautions that natural variability's ups and downs average out over long periods, and did not play the primary role in the century-scale warming trend.
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Kevin C at 17:04 PM on 3 September 2013The Pacific Ocean fills in another piece of the global warming puzzle, and puzzles Curry
Hmm. That graph looks familiar. Where have I seen it before?
Oh yes. Here:
Their result is a good match for my toy 2-box+ENSO model from last year, but far more rigorous. Tamino has produced a very similar model.
You can play with it online here. It produces a good match for IPCC TCR estimates, but the results are of course totally controlled by the uncertainties in the forcings, so that doesn't prove anything. I think the Potsdam forcings omit 2nd AIE (is that in the glossary?), so you have to upweight AIE by 50%. What it does show is that curent forcing estimates can explain 20thC climate very well.
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spoonieduck at 15:58 PM on 3 September 2013Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
tcflood,
You are Way over my head. I'm but an interested dilettante in this man-made global warming stuff. Still, I have some observations which may or may not be pertinent to anything. Consensus: Who was polled to establish the so-called Consensus? Climatologists? Weathermen? Physicists? Sociologists? Petroleum Engineers? Volcanologists? Ecologists? Paleontologists? Archaeologists? Pathologists? Dentists? For sure, nobody polled me.
Also, science isn't about consensus. Science is the effort--sometimes the painful effort--to get at something approaching the truth. At one time "consensus" had it that the four humors were responsible for health and disease. At one time "consensus" had it that the sun revolved around the earth. At one time "Consensus" had it that most cancers started with one great mutational 'hit'. "Consensus" is a misleading term if there ever was one.
So much for my soap box. The other day I was watching a TV show--the source of most of my scientific information. The Journalist was interviewing scientific types. One was a young woman digging away in the melting Alaska permafrost. They filmed impressive looking sink-holes caused by melting ice. She climbed down into a sink-hole [looked risky to me] and showed melting frozen earth, 2-4 feet deep, containing clusters of roots from "plants that died hundreds or thousands of years ago."
Hmmm. Either these were the roots of plants that could grow in solid ice OR climate was a lot warmer in the far North way back then. [Little Climatic Optimum?]. How could it have been warmer 'hundreds of thousands of years ago, when it's supposed to be warmer NOW than since, if not before, the last interglacial? What do you think?
I know. The exception proves the rule. Still, they went on to claim that, at the present rate, by the end of the century, atmospheric CO2 would be twice that of today and the fish would boil in the sea [that's a joke]. Anyway, I googled it and did some high school arithmetic. Maybe I made a couple of systematic errors but, looks like, if we burned All petroleum and natural gas tomorrow, we would increase the tonnage of CO2 in the atmosphere by .001%. Note, this isn't saying that the % in the earth's atmosphere would go up that much. It means that atmospheric CO2 would go up a tiny fraction--IF--we burned it all at one time. Of course, all that petroleum-produced CO2 might hug the ground and heat up the surface a lot because, as we know, manmade CO2 is a lot different from 'natural' CO2.
Also, I worry a lot about carbonates. I live on a hill loaded with sea shells, ammonites, snails etc. that died tens of millions of years ago. The 'turn-over' rate is pretty slow and my guess is that they'll be locked in the rock another 65 million years. It occurs to me that the same thing is happening in the sea today. Sea life--especially those with shells--must be locking up plenty, plenty of carbonates. Once locked, they are generally fixed unless cooked and vaporized by volcanoes.
Moderator Response:[DB] In addition to the sage advice already given you below, please read The Big Picture thread for background...and familiarize yourself with this site's Comments Policy.
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Bernard J. at 15:40 PM on 3 September 2013The Pacific Ocean fills in another piece of the global warming puzzle, and puzzles Curry
As I noted last week at Hot Whopper the authors did no favours for themselves or the interpretation of their paper by using the term "hiatus" without any prefacing modifiers.
It's important to emphasise that there is no hiatus in overall global heat accumulation - only a redistibution such that the surface of the planet manifests less of the overall heat accumulation. This is of course what Kosaka and Xie are describing, but the Denialati have run with the ambiguous phrasing and released their own twisted meme to the world whilst Precision stands waiting for Truth to finish lacing its boots so that the former personage can pull on its own footwear.
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tcflood at 12:03 PM on 3 September 2013Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
MThompson @88;
How black body-like the earth's emission is depends on the details of the specific piece of surface, but on the average I think the consensis is that it is about 90% BB-like. So, yes, the earth's IR emission in the region around 700 cm-1 is absorbed efficiently by the CO2. The key point here, though, is that in the troposphere that excited CO2* (* means excited state) undergoes about 10^10 collisions each second and the excitation energy is transferred at about that rate to all the gases in the immediate vacinity, thus, contributiong to the thermal pool. The rate of spontaneous emission in the mid IR range tends to correspond to lifetimes of the excited state on the order of milliseconds, which is way too long for the specific originally excited CO2* (lifetime of a few hundred picoseconds) to have any probability of just emitting the photon directly back out. Thus, the low equilibrium percentage of CO2* in the atmosphere can essentially be thought of as coming entirely from the Boltzmann thermal equilibrium and this is the population from which re-emission of the IR occurs.
It sounds like your population of from 6-15% of CO2* may have been calculated assuming the ground state is singly degenerate. I think the ground state and excited state are both doubly degenerate for the bending mode so the percentages may be half of that. I'm not sure on this point. Maybe someone else can comment.
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K.a.r.S.t.e.N at 09:32 AM on 3 September 2013Study offers clues on 20th century global warming wobbles
Interesting paper with a different approach to a long-standing problem. Well worth a read, though some aspects are certainly debatable. One thing in the paper that I tend to disagree with is the authors notion that aerosol effects are likely less over oceans. Given the low albedo, even a small increase in aerosol the loading matters (more than over land). To their credit, the SH oceans are indeed less affected, although this might have changed in the last decade. All effects together, I don't think they overestimate the global temperature trends due to aerosols with their land only results.
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MThompson at 08:32 AM on 3 September 2013Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
tcflood @87
Thank you for the clear explanation of how the rotational modes broaden the primary transitions. I am still trying to understand how the bending vibrational mode of CO2 gets populated. I see from the Maxwell-Boltzman distribution that about 6% to 15% of gas molecules at earth temperatures have enough kinetic energy to excite the CO2 bending mode. Now my question is: “Do photons from the earth’s blackbody spectrum in the range of 13-18 microns ( 770 to 560 cm-1) pump ground-sate CO2 molecules to the bending mode?”
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BillEverett at 04:01 AM on 3 September 20132013 SkS Weekly Digest #35
The bad link was serendipitous for me. I clicked the link in comment 1 and found something I want to follow. Thanks for the link error and resulting comment!
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CollinMaessen at 03:56 AM on 3 September 20132013 SkS Weekly Digest #35
Cheers. :)
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tcflood at 03:10 AM on 3 September 2013Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
MThompson @86,
At atmospheric temperatures only a few percent of CO2 molecules are in the first vibrationally excited state. All the rest are in the vibrational ground state. Thus, vibrational transitions to higher levels are not involved. The broadness of the bending mode comes from the fact that each vibrational state has a large number of rotational levels populated, and vibrational transitions can be from a lower to a higher rotational level ("R-branch" transitions) or from a higher to a lower rotational level ("P-branch" transitions). The rotational component of the one vibrational transition can broaden the spectral absorption band by hundreds of wavenumbers. These ever more wide-spread transitions, by the way, are why the CO2 absorption band (and water bands, for that matter, never fully "saturate" with increasing levels of water and CO2 in the atmosphere.
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dvaytw at 01:05 AM on 3 September 2013It's El Niño
Rob thanks.
I understand why as a serious scientist you don't want to spend time on crank ideas. That said, I'm debating people in online forums where there are a lot of non-science people, and pseudo-scientists often know their pseudo-science better than do those defending the real science, which means they can actually appear to be winning debates even when wrong - and this can influence people's opinions.
This is why I make the effort to actually find out what's wrong with Tisdale's "hypothesis" - because a fellow in a debate is using Tisdale's video about ENSO (which specifically targets SkS, incidentally!), and for the scientifically challenged, it can seem convincing.
So based on your response, my next question is this: how do we know that "over time, in a stable climate, they would balance out to zero?" I seems in the information provided above, our measurements only go back to 1980. -
John Hartz at 00:20 AM on 3 September 20132013 SkS Weekly Digest #35
Collin Maessen: Link fixed. Thank you for bringing this to our attention. Also, thank you for all that you do.
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MA Rodger at 18:02 PM on 2 September 2013Study offers clues on 20th century global warming wobbles
The headline numbers for climate-watchers will be the impact of Rs on Global Land Temperatures shown in Fig 6a & also presented in Table 1 as rate of change per century yielding on the back of my envelope - 1900-39 +0.02C, 1940-84 -0.16C, 1985-2010 +0.017C, with this last period starting in the aftermath of the El Chichon eruption.
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One Planet Only Forever at 15:13 PM on 2 September 2013Global warming...still happening
Daniel,
There are many people who are looking for any possible excuse to believe that activity they benefit from is not a problem. There is a very sucessful deceptive marketing effort that preys on that desire. It uses any means to delay global action that would actually significantly reduce the burning fossil fuels.
So my comment remains that using a comment like "the past decade was the warmest" will be successfully abused by the decievers and delayers saying "we need to wait for the next full decade of data before we do anything". If you are not careful about what you try to argue with you can make it easier for someone to "beleive what they prefer to believe", even if you know they have misinterpretted the point you were tryng to make.
The warming of the earth due to human activity is indeed beyond scientific dispute. It has been for more than a decade. This issue is now political. How something is said matters more than the actual facts in politics. The best way to deal the decievers is to present infromation that is very difficult to "take advantage of". You have to remember that much of the population has "a vested interest in not properly understanding this issue". Much of the population cares more about getting more benefit for themselves than they do about future consequences others will face.
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CollinMaessen at 14:16 PM on 2 September 20132013 SkS Weekly Digest #35
I noticed that when my website is referenced that it's pointing to some internal link on SkS that apparently requires a login. For anyone that is interested you can find the referenced blog post here.
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MThompson at 14:00 PM on 2 September 2013Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
Phil @82
Daniel @84
Thanks for pointing out how the energy distribution factors into this. After reading your comments I did quite a bit of poking around online to refine my understanding. The big CO2 peaks may overlap some with molecular water, but the CO2 components seem to span a wavelength range of roughly 13-18 microns. Does this range correspond to higher quantum number states of the bending mode? It seems transitions between asymmetric stretch and bending mode have wavelength of about 9.5 microns.
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Daniel Bailey at 12:27 PM on 2 September 2013Toward Improved Discussions of Methane & Climate
Northbeacher, rather than continuing on in your variant of your arguments from personal incredulity, note that the OP is written by a climate scientist and repeatedly references the primary literature, so asserting your own personal opinions to the contrary carry little weight here.
Given the vast differences in amounts being injected back into the carbon cycle, CO2 has a much greater Radiative Forcing than does methane. And that's the most important consideration, not the Global Warming Potential of the various gases.
FYI, for the Arctic, the OH radical found there is primarily produced in the tropics and then transported poleward (source).
[Source]
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Northbeacher at 10:50 AM on 2 September 2013Toward Improved Discussions of Methane & Climate
My personal thoughts on this article. Okay, I realize we all go off on excessive tangents on occasion, myself included, and maybe my retort is yet another example of that, but...
But this article begs that I protest. Because the world is in great peril from global warming. From the feedback loops of global warming. From the ireversible tipping point thresholds of the feedback loops of global warming. From the abrupt "climate change" [sic] that will result...
Yes, many of the feedback loops are methane related, but there are many more KNOWN major feedback loops which this article ignores. Add to the known feedback loops the new UNKNOWN feedback loops, which are constantly being discovered...
The planet is in exponentially imminent danger of a failing to support its increasingly overpopulated hoards.
Dirty energy and its charlatan shills are much too effectively dumbing down voters to continue having their dirty way with destroying the planet.
So, someone overstates -- debatably, somewhat -- that the planet is collapsing. So what? Why go to such extensive extremes to refute it? Seems voters need some counter-bullshitorama to push them into voting out climate deniers rather than downplaying and lowballing the reality of what we are truly faced with.
This article brings new meaning to "wrong headed", if not, as previously noted, just plain wrong in at least a couple of aspects, but frankly, many more that I did not (yet?) take the time to expose...
IBM in the 60's used to have the simple motto of "Think". Consider that in your future endeavors to protect the human habitat from those mindless morons that destroy it in the name of greed. Voters need to wake up, not be lulled into complacency by articles like this. Shame on you...
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Jonas at 10:08 AM on 2 September 2013The Beginners Guide to Representative Concentration Pathways - Part 3
Thank you for this in depth introduction!
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Northbeacher at 10:01 AM on 2 September 2013Toward Improved Discussions of Methane & Climate
Substantiating my earlier contention that methane should not be summarily dismissed...
Methane is 20 times more potent as a greenhouse gas than carbon dioxide. This recent lecture by James Hansen of NASA notes methane regulation has more short-term potential to slow climate change than does carbon regulation.http://www.columbia.edu/~jeh1/2009/Copenhagen_20090311.pdf
Given that methane is about 25 times stronger as a greenhouse gas per metric ton of emissions than carbon dioxide...
http://www.nasa.gov/home/hqnews/2008/oct/HQ_08-276_Methane_levels.htmlMethane, with a warming potential 72 times that of carbon dioxide over a 20 year time frame, having a half-life of only 7 years.
http://www.dailykos.com/story/2013/06/19/1217235/-MIT-Climate-Fast-Solution-to-Climate-Change-Is-On-Your-Plate#Pound for pound, the comparative impact of CH4 on climate change is over 20 times greater than CO2 over a 100-year period.
http://www.epa.gov/climatechange/ghgemissions/gases/ch4.htmlOver 100 years, a ton of methane would heat the globe 23 times more than a ton of carbon dioxide.
http://oceana.org/en/our-work/climate-energy/climate-change/learn-act/greenhouse-gasesMethanes Lifetime Global warming potential over CO2
20-yr 12 times 100-yr 72 times 500-yr 7.6 times
https://en.wikipedia.org/wiki/Greenhouse_gas#Greenhouse_gases -
Northbeacher at 09:07 AM on 2 September 2013Toward Improved Discussions of Methane & Climate
Methane is 23 times stronger as a greenhouse gas than Carbon Dioxide in the short run and 72 times stronger in the long run. I have noted variations of that statement hundreds of times by credible scientific sources. This article seems to state something on the order of the opposite?
For brevity, singling out just one other minor point the article makes on methane, where hydroxyl radicals counter CH4...
First on the highly ephemeral hydroxyl molecules: they are produced when ultraviolet radiation bombards common gases such as ozone and water vapor. The resultant OH molecules typically have a lifetime of less than one second because they immediately react with various gases (not just methane).
Secondly, the shrinking ozone hole contributes to producing extra hydroxyl radicals. As the ozone hole recedes -- and an ever thicker greenhouse shield blocks more ultraviolet radiation -- so to does the production of hydroxyl molecules recede.
Thirdly, as pollution, smog, and brown haze increase, a feedback threshold may eventually be crossed such that the hydroxyl oxidation process goes into sharp decline, ceasing to be a significant offsetting factor.
I could go on and on, as their are other sources of the methane bomb unmentioned in the article, but this is just a "comment" and my brief point has been made.
So, in abbreviated conclusion, I am perplexed... Is it even remotely possible the author is downplaying the methane gorilla in the greenhouse for some reason?
Moderator Response:[DB] "Is it even remotely possible the author is downplaying the methane gorilla in the greenhouse for some reason?"
Speculation to motive contravenes the Comments Policy in this venue. Please focus on the evidence.
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Daniel Bailey at 05:01 AM on 2 September 2013CO2 lags temperature
Tzedakis et al 2012 found that the threshold for the current interglacial / glacial transition was about 240 ppm CO2, so that is in-line with other research.
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tcflood at 04:46 AM on 2 September 2013CO2 lags temperature
Daniel,
Thanks for your response. An especially interesting feature of their modeling results is that if [CO2} is kept constant at 220 ppm, the model still produces the 100 ky ice age cycle. If [CO2] is kept constant 260 ppm, the ice ages disappear. If [CO2} is kept constant at 160 ppm, the ice age frequency is much higher and interglacials are much colder.
These models point to non-linear coupling of numerous variables that is indeed complex. From my point of view, it is exciting to finaly see a quantitative treatment that actually does reproduce the periodicity, shape, and intensity of the ice age/interglacial cycles. Now perhaps they can begin to really nail down the explicit quantitative role of [CO2] in all of this and finally lay the "lag" BS to rest.
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tcflood at 04:27 AM on 2 September 2013Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
KR @80
Can you give a reference for your stated radiative lifetimes? I thought spontaneous emission in the mid IR (at the CO2 bending mode) had lifetimes on the order of milliseconds, not microseconds.
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Daniel Bailey at 04:18 AM on 2 September 2013Global warming...still happening
"some may claim the need to "wait for the next decade of data" before having to admit anything"
Some still claim the Earth to be flat. Empirical, observational evidence and physics demonstrate otherwise.
"a claim could be made that the decadal rolling average has stopped climbing, because it has"
Circular reasoning bordering on sloganeering. The ongoing energy imbalance at the Top Of our Atmosphere (TOA) amply demonstrates the utter, physics-less falsehood of this statement. A claim could be made that sheep's bladders could be employed to prevent earthquakes. So what?
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Daniel Bailey at 04:06 AM on 2 September 2013CO2 lags temperature
tcflood, the Nature paper is important in that the modeling efforts are able to successfully simulate the various ice age cycles, including the 100,000 year cycle, by successfully identifying and accounting for the various knock-on feedbacks. These feedbacks include albedo, CO2 levels, ice sheet configuration (including elevation), air- and ocean-circulation changes.
The researchers obtained their results from a comprehensive computer model, where they combined an ice-sheet simulation with an existing climate model, which enabled them to calculate the glaciation of the northern hemisphere for the last 400,000 years. The model not only takes the astronomical parameter values, ground topography and the physical flow properties of glacial ice into account but also especially the climate and feedback effects.
Using the model, the researchers were also able to explain why ice ages always begin slowly and end relatively quickly. The ice-age ice masses accumulate over tens of thousands of years and recede within the space of a few thousand years. Now we know why: it is not only the surface temperature and precipitation that determine whether an ice sheet grows or shrinks. Due to the aforementioned feedback effects, its fate also depends on its size.
The paper confirms, via modeling, that the aforementioned effects (combined with Milankovitch orbital forcings) can account for the various iterations of the ice age glacial / interglacial cycles.
Above quotes are from the Phys.org article linked below.
http://phys.org/news/2013-08-ice-ages-feedback.htmlThe Shakun et al 2012 paper showed that warming was indeed triggered by the Milankovitch cycles, and that small amount of orbital cycle-caused warming eventually triggered the CO2 release, which caused most of the glacial-interglacial warming. So while CO2 did lag behind a small initial temperature change (which mostly occurred in the Southern Hemisphere), it led and was the primary driver behind most of the glacial-interglacial warming.
According to the Shakun data, approximately 7% of the overall glacial-interglacial global temperature increase occurred before the CO2 rise, whereas 93% of the global warming followed the CO2 increase.
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tcflood at 03:27 AM on 2 September 2013CO2 lags temperature
RE: 397-399
Let me try again:
Here is a paper.
What is the SkS take on it?
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One Planet Only Forever at 03:21 AM on 2 September 2013Global warming...still happening
Daniel @ 16.
I would caution against the presentation of decadal averages without also showing the trend line of rolling averages of a decade of data. A new decadal average can be claculated for each new month of data. However, some may claim the need to "wait for the next decade of data" before having to admit anything. Also, a claim could be made that the decadal rolling average has stopped climbing, because it has. However, averages of larger sets of data that would include the recurrance of signifcant variable factors such as El Nino continue to climb.
The numbers and statistics game can be played in many ways. Even the 30 year average shows fluctuations resulting from the many variable and random factors that affect Global Average Surface Temperature.
What is important, and challenging, is the presentation of information in a way that will make it harder for people to "believe what they prefer to believe".
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Andy Skuce at 02:02 AM on 2 September 2013The Beginners Guide to Representative Concentration Pathways - Part 3
I don't think it is fair to say that CCS is not working, at least at a technical level, the few pilot projects that are running seem to be working OK. The problems with CCS are economic, scalability and regulatory.
The economic problem could be solved with a hefty carbon tax, which is easier said than done, of course.
The scalability problem is much more problematic, since the mass of CO2 that has to be stored is about three times the mass of the fossil fuels that produced it. Establishing a new global industry much bigger than the current oil, gas and coal industries in a matter of decades is not feasible. Note that in all of the RCPs, the absolute amounts of fossil fuels consumed increases by 2100. The scalability problem is not so much a question of the size of the potential reservoirs, but our ability to build the infrastructure to put the CO2 there.
The regulatory problem is a major stumbling block in my opinion. Geological CCS has all of the problems of unconventional gas development and more and, if it is to be a climate-relevant solution, it will have to be implemented in sedimentary basins everywhere. The potential hazards of CCS are real and include leakage, earthquakes, industrialization of the landscape and groundwater contamination. The regulatory and public acceptance problems will make CCS more expensive, slower to implement and more limited in scope.
rustneversleeps and I wrote a long piece on CCS recently that covered some of these points in more detail.
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owenamoe at 00:01 AM on 2 September 2013Global warming...still happening
Global warming is produced by an energy imbalance at TOA, an imbalance which is evidenced most clearly in accumulating ocean heat content. I would suggest that you use the latest NOAA values for OHC (http://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/basin_data.html) which show, through the first quarter of 2013, an unabated rise in heat accumulation on earth (as oceans absorb ~93% of that imbalance). The atmospheric temperatures, due to the far, far lower heat capacity of the atmosphere relative to the oceans, and driven by the current set of ocean-atmosphere heat transfer mechanisms (ENSO, PDO, AMO, thermohaline circulation, etc), provide the least reliable assessment of an energy imbalance at TOA is derived from atmospheric temperatures. A ton of statistics on a poor indicator is not particularly helpful.
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michael sweet at 19:41 PM on 1 September 2013The Beginners Guide to Representative Concentration Pathways - Part 3
Perhaps I am behind the times, but my understanding is that none of the CCS schemes is working. Does anyone have a link to an up to date summary of the status of CCS? If CCS does not yet work, it will be difficult to implement in a timely fashion.
On the other hand, wind and solar continue their amazing drop in cost. Wind is already the cheapest new source of energy and will soon be cheapest even compared to coal plants that are paid for. Solar is economic for home installation in areas with expensive electricity and will soon be economic everywhere. I have started to look at how to install solar at my home in Florida even though Florida has no incentives.
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Rob Painting at 18:15 PM on 1 September 2013It's El Niño
dvaytw - it's not strictly true that El Nino and La Nina simply move heat around. But over time, in a stable climate, they would balance out to zero. The only reason the climate system is gaining energy in the long-term is because the increased Greenhouse Effect is trapping more heat in the surface ocean.
That's why global temperature, and therefore subsurface ocean temperature, tracks atmospheric CO2 so well in the ice core records over the last 800,000 years.
I don't consider it a worthwhile exercise spending time on crank ideas from Bob Tisdale.
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Rob Painting at 17:50 PM on 1 September 2013CO2 lags temperature
tcflood - the abstract is here: Abe-Ouchi et al (2013) - Insolation-driven 100,000-year glacial cycles and hysteresis of ice-sheet volume.
Sounds interesting. Note that it relates to the 100,000-year cycle - as stated in the abstract:
"Carbon dioxide is involved, but is not determinative, in the evolution of the 100,000-year glacial cycles."
Your comment omits this crucial bit of information.
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tcflood at 16:08 PM on 1 September 2013CO2 lags temperature
Sorry. For completeness, the authors on that Nature paper are Ayako Abe-Ouchi, Fuyuki Saito, Kenji Kawamura, Maureen E. Raymo, Jun’ichi Okuno, Kunio Takahashi, and Heinz Blatter.
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tcflood at 15:58 PM on 1 September 2013CO2 lags temperature
I have always been bothered by the lack of a detailed and convincing explanation for the 100 ky periodicity of the last four ice ages when the periodicity of northern temperate zone insolation intensities from Milankovich cycles (my understanding is that this is the important component of these cycles) is close to 20 ky. A recent paper in Nature (Vol 500, August 8, 2013, page 190) presents an explicit explanation and also describes how CO2 has a role but is not determinative in ice age/interglacial cycles. What do you people at SkS think about this paper?
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dvaytw at 15:39 PM on 1 September 2013It's El Niño
Thanks for the info, Rob, but what do you think of my characterization of the problem with his hypothesis? I'm trying to sum it up in a way that is hospitable to people like myself without a solid science background.
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Dave123 at 11:36 AM on 1 September 2013Global warming...still happening
I'm imaging the climastrology reponse to Dan Bailey's repost of the excellent Climate Central graphic-
begin simulation exercise
'Ya see...we had 4 steps up and a plateau from 1900-1940, so we've had 4 steps up now, so we're due for another plateau!!! If only climate scientist could count with the fingers on one hand'
(end simulation exercise).
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