Recent Comments

Prev  1759  1760  1761  1762  1763  1764  1765  1766  1767  1768  1769  1770  1771  1772  1773  1774  Next

Comments 88301 to 88350:

88301. Gilles at 08:08 AM on 17 April 2011
       What was it like the last time CO2 levels were this high?
       34 : climate has never cooled after Pliocene ? 35 : I don't think your answer is really one, since world population has increased by several billions - it may BTW be interesting to know that the 30000 deaths have been almost compensated by a corresponding decrease the year after, most of them being old people having shortened their life by a few months. Sad enough, but you don't intend to be immortal do you ? and do you really hope avoiding all this kind of events by reducing FF ? "Uh, CO2 levels went down?" : yes but .. why ? 37 : my point was the rise of temperature didn't prevent population from growing - i did not state that it grew thanks to FF , ( although it is pretty obvious), but that temperature did not prevent it. So my question was : when will it do it ? Now it this OT, you should have said that to Villabolo already at #9 and #31 - why do you notice only my answers ? Concerning Pliocene, I'm far from being an experts, but some googling led me for instance to that : "In addition to the above experiment, several simulations were conducted using increased levels of atmospheric carbon dioxide; higher CO2 amounts have also been proposed as a potential cause of the warmer Pliocene climates (Crowley, 1991). Rind and Chandler, (1991) pointed out that SST patterns such as the one seen in the Pliocene are inconsistent with CO2 generated warming, however, it is possible that some combination of CO2 increase and ocean heat transport change could have resulted in the warmer Pliocene surface temperatures. Figure 3 shows the various levels of ocean heat transport required to generate the PRISM SSTs given various atmospheric CO2 increases. The graph indicates that with modern ocean heat transports (0% increase) CO2 levels must have been at least 1400 ppm (4.5 times the modern value) in order to generate the global warming of the Pliocene. So far, estimates based on carbon isotope measurements by Raymo and Rau (1992) suggest that Pliocene CO2 levels were, at most, 100 ppm greater than today." well, I don't know if they're right, but it seems that they claim that CO2 is responsible only of 10 % of the warming or so (much in line with what I explained on feedbacks :) at least it is a possibility , which means that it is by no way granted that it makes sense to compare CO2 levels and temperatures to current ones. Comments ?
       Moderator Response: [Muoncounter] An astonishing reply, Gilles, even for one with your track record. Heat wave deaths among the elderly are 'compensated' for the following year? Nice compassionate worldview you have.
88302. villabolo at 08:06 AM on 17 April 2011
       What was it like the last time CO2 levels were this high?
       @33 Gilles: "would survive what ?" Gilles, you do amaze me. To your first question as to what humanity would survive (give me some time to chuckle) he simple answer was given when I described Lovelock as a believer (Me too) of CAGW. Spelled out that means "Catastrophic Anthropogenic Global Warming" No, I'm not one for meticulous and mathematical details but I'll throw this in. 10 degrees Fahrenheit above pre-industrial levels. I seriously don't think that this civilization will not go over 600 ppm because economic downturn/collapse (sometime before we reach 600 ppm) brings our consumption spiralling down. That may not be enough for a 10F increase but then there are pesky things like the Siberian permafrost/defrost. Please see video below. "http://www.youtube.com/watch?v=vSLHvZnbYwc&feature=related "As far as I know, the huge increase of population is correlated with an increase of FF consumption and an increase of temperature - so if any, the "negative" influence of increasing temperature has been largely offset by the positive effect of energy availability - or the huge modern demographic growth would be totally incomprehensible." Gilles, it's the use of FF that is digging our graves. Incomprehensibility of population growth is irrelevant. I know it is due to Carl Bosch developing the conversion of natural gas to synthetic fertilizers in 1913. So what? To use an analogy, you can grow fat on junk food; then you die. As for negative effects being counterbalanced by "positive" effects, tell that to the Egyptians who pay 40% of their salaries for staple foods. Let's connect the dots. There have been multiple crop failures throughout the world causing a spiraling in grain prices. Winter/Summer of 2010/2011: a. Russia/Ukraine: Up to 40% failure of wheat crop due to severe drought and high temperatures. They are major wheat exporters. b. Pakistan: 20% of its land inundated by floods. They had to import food. c. Australia: Major damage to wheat crops due to intense rains (from warming oceans). They are a major wheat exporting nation. d. Argentina: Soybean and corn crop loss due to drought. e. Canada: Damage to wheat crop due to intense rains. They too, are a major wheat exporting nation. f. China: Loss of almost the entire winter wheat crop. Neither an exporter or importer of wheat, China has been self sufficient in that crop. Not that it matters because they have a huge population that will need to import grains. g. Mexico: Major loss of corn crop. They have had to import 50% more corn from the US than previously. No; it's not the individual crop failures that can be pinned to AGW; it's the number and frequency. Expect more of he same throughout the rest of this decade. It's up to you to calculate the "negative" effects (quote marks yours). Now please give me a simple argument to tell me when the negative effect of an increase of temperature would be much larger that the positive effect of increasing energy consumption -and conversely the positive effect of avoiding the increase of temperature would be much larger that the negative effect of suppressing 80 % of the energy consumption- since the whole history demonstrates exactly the opposite ?" [Underlining mine] "It's this simple, Gilles. It's already happening. Furthermore, your concept of the "positive" effects of FF, irrespective of the AGW issue, is questionable; but that's another story. As far as the negative effect of decreasing our consumption of FF by 80%, I am of the opinion that we have to cut our consumption by 90% within the next 10 years. That is enough to make some of the forum members here gulp. Of course, 'Skeptics' will get a hernia (due to intense laughter) when they hear that. But this is how I perceive the situation. If we take the "extreme" measure of reducing FF consumption by 90% in the next decade, then we will get our teeth kicked in by AGW. No ifs, ands or buts. This will be, in major part, due to the Arctic Ice Cap shrinkage and its drastic effects on our climate in the Northern Hemisphere. This will include the acceleration of the Siberian permadefrost, and the subsequent increase in the metabolism of the methanogens that are releasing ... methane. Positive feedback, you know. It's too late to stop that IMO. The Arctic Ice Cap went past the tipping point long ago. Those who say otherwise are probably not taking the 1F of increased heat that we're due in the next 30 years. That assumes that we magically stop all FF emissions cold and right this minute. Thermal lag you know. However, if we don't take the drastic actions I've proposed or we take symbolic and token actions (as I predict will happen by decade's end) then we're going to get our teeth kicked in and, a few decades down the road, our skulls bashed in. Nice choice, isn't it? Bottom line, Gilles, you don't calculate and scratch your head when it's time to slam the brakes. I hope this answer has been simple enough. I'm sure I forgot a few things, however.
88303. Bob Lacatena at 07:07 AM on 17 April 2011
       What was it like the last time CO2 levels were this high?
       33, Gilles,

       Really? why has it cooled meanwhile, then ?

       If you need to ask this, then you have some studying to do.

       As far as I know, the huge increase of population is correlated with an increase of FF consumption and an increase of temperature...

       One upon a time, my own height was well correlated with my age. As I aged, I grew. I should probably be about 100ft tall by now.

       ...please give me a simple argument to tell me when the negative effect of an increase of temperature would be much larger...

       Because extreme increases in temperature will result in major desertification and other ecosystem changes, as well as the alteration of climate zones (i.e. growing seasons). More importantly, major changes in precipitation patterns and large, difficult to endure droughts will greatly reduce crop productivity, leading to widespread famine. It certainly won't help, either, when the productivity of the ocean as a food source plummets because of acidification. This will probably take 50 to 100 years, but once it starts, there will be no going back. This is the game that you are so callously playing with civilization. Now can you please go back to the topic, instead of dragging the thread into your own personal conversation about whatever you want to talk about?
88304. Chris G at 07:05 AM on 17 April 2011
       What was it like the last time CO2 levels were this high?
       Here as an interesting article along the same lines where Csank was a co-author, Significantly warmer Arctic surface temperatures during the Pliocene indicated by multiple independent proxies (No pay wall) Gilles, Re: "Really? why has it cooled meanwhile, then ? " Uh, CO2 levels went down? What makes you think that the planet will behave differently now than it has under similar conditions in the past? You are asking us to spoon feed you information that you can readily look up yourself. Examples: Damaging effects ocean+acidification Hadley+Cell heat+crop+production (The one on plant stress is very pertinent.) Or, maybe you should examine the links between the Russian heat wave last year and unrest in the Middle East this year. Hint: Where did Russia used to sell a lot of wheat in prior years? What causes CO2 levels to change and how does that affect the climate? You are diverging from a reasonable argument with holes in it into something else. You have asked repeatedly what, other than man, causes changes in CO2 levels, and repeatedly you been directed how to find that information. Please quit asking the same question. Yes, quantitative, that is what this article and others like it are about. Sometimes I find this useful: Rational Discussion Rules
88305. Bob Lacatena at 06:43 AM on 17 April 2011
       Clouds provide negative feedback
       7, RW1,

       ...the data doesn't conclusively show that on average they trap more energy than reflect away...

       What data? Again, citation please. Although, I'd point out that as with everything, the climate has barely begun to reflect the changes. We haven't come close to doubling CO₂ yet, and we've only seen half of the 1.4˚C of warming to which we've already committed. So the data isn't very likely to conclusively show anything, but that hardly makes it an argument that something is wrong.

       It takes +16.6 W/m^2 at the surface for a 3 temperature rise.

       Where are you taking this from?

       ...the system gain or system amplification...

       You're an electrical engineer.

       ...which is a factor of about 1.6 (390 W/m^2/239 W/m^2)

       Again, where are you getting this math from? Do you have a source, or is it your own inference?

       In simple energy balance terms, it takes about 390 W/m^2 at the surface to allow 239 W/m^2 to leave the system...

       No. This is a gross oversimplification of the problem, and will lead to errors. It is also flat out incorrect. Study this: Notice that the energy entering the system from outside is only 184 W/m², and only 161 W/m₂ of that is absorbed.

       In short, if it is going to take an additional 16.6 W/m^2 to allow 3.7 W/m^2 to leave the system to restore equilibrium, then why doesn't it take 1075 W/m^2 at the surface to allow the 239 W/m^2 from the Sun to leave the system at initial equilibrium (16.6/3.7 = 4.5; 1075/239 = 4.5)???

       Because your premise, that "it will take an additional 16.6 W/m²..." is incorrect.
       Moderator Response: [muoncounter] This gain theory/calculation was discussed in excruciating detail on Lindzen and Choi find low sensitivity. Please do not restart it here.
88306. windbarb at 06:36 AM on 17 April 2011
       Muller Misinformation #3: Al Gore and polar bears
       Enginerd raises a really important point. At what point is the defamation and fraud of the false claims (Muller's, Christy's, and the twisted words from Climategate, just to name a few) legally actionable? If it was actionable, who would be the complainant? And how can universities who employ those who misrepresent facts so blatantly continue to employ them? (Moderators, I understand that this might be a tangent that belongs on another thread.)
88307. muoncounter at 06:25 AM on 17 April 2011
       What was it like the last time CO2 levels were this high?
       Gilles#33: "the huge increase of population is correlated with an increase of FF consumption and an increase of temperature" Ah, the good old correlation equals causation game. We can use that now? "please give me a simple argument to tell me when the negative effect of an increase of temperature would be much larger that the positive effect of increasing energy consumption" Apparently you missed the more than 30000 deaths during the European heat wave of 2003? Odd that a society so rich in the positive effects of energy consumption would suffer so much hardship during a mere localized heat wave. Firefighters know this to be true: “It is easier to stay warm than it is to stay cool in all this gear,” he said. “Once you get overheated, it is really hard to get cooled off. You have to be out in the cold like this a long time before it will affect you systemically, whereas in the heat like that, in 15 or 20 minutes, guys start dropping if you don’t rehab them.”
       Moderator Response: Gilles, a more relevant thread for your claims is "It's Not Bad."
88308. batsvensson at 06:10 AM on 17 April 2011
       Video on why record-breaking snow doesn't mean global warming has stopped
       What led you to such understanding ? "In 1937 [Sir George Clarke Simpson] suggested that, paradoxically, an increase of solar radiation might bring on an ice age."
88309. batsvensson at 06:09 AM on 17 April 2011
       Video on why record-breaking snow doesn't mean global warming has stopped
       Global Warming Means More Snow For Great Lakes Region ScienceDaily (Nov. 6, 2003) — Global warming has had a surprising That is not a prediction JMurphy
88310. JMurphy at 05:55 AM on 17 April 2011
       What was it like the last time CO2 levels were this high?
       Gilles wrote : "Really? why has it cooled meanwhile, then ?" What has cooled, and since when ?
88311. Tor B at 05:35 AM on 17 April 2011
       Muller Misinformation #3: Al Gore and polar bears
       To see video evidence of drowned polar bear cubs associated with Global Warming related retreating sea ice, see this PBS footage. It's just two and a half minutes long.
88312. Gilles at 05:32 AM on 17 April 2011
       What was it like the last time CO2 levels were this high?
       ChrisG : "In the Pliocene, the position of the continents, the output from the sun, and the orbital mechanics are largely the same as they are now; so, we should expect a similar thermodynamic equilibrium from a similar atmospheric composition." Really? why has it cooled meanwhile, then ? Villabolo : "Gilles, oh Gilles. Please keep in mind that there is a difference between humanity per se and civilization. James Lovelock, author of the Gaia Hypothesis and believer in CAGW, says that as little as 100 million human beings would survive." would survive what ? As far as I know, the huge increase of population is correlated with an increase of FF consumption and an increase of temperature - so if any, the "negative" influence of increasing temperature has been largely offset by the positive effect of energy availability - or the huge modern demographic growth would be totally incomprehensible. Now please give me a simple argument to tell me when the negative effect of an increase of temperature would be much larger that the positive effect of increasing energy consumption -and conversely the positive effect of avoiding the increase of temperature would be much larger that the negative effect of suppressing 80 % of the energy consumption- since the whole history demonstrates exactly the opposite ? DM : I am completely ready to admit that CO2 contributes to warm the atmosphere , on very simple arguments of radiative transfer. My only questions are quantitative.
       Moderator Response: [Dikran Marsupial] If your questions about CO2 as a greenhouse gas are quantitative, then there are a variety of threads here that examine climate sensitivity. There are many knowledgeable contributors here who I am sure would be happy to discuss quantitative issues with you there. If you are not happy with GCMs, you might want to look at earlier work by Gilbert Plass performed back in the 1950s and getting a result in the same ball park as today's GCMs (see RC article for caveats).
88313. RW1 at 04:42 AM on 17 April 2011
       Clouds provide negative feedback
       Sphaerica (RE: 6), When there is a radiative imbalance, i.e. from additional CO2 added to the atmosphere which redirects more outgoing surface radiation back toward the surface, there is reduction in the amount of LW radiation leaving at the top of the atmosphere (more radiation is arriving from the Sun than is leaving at the top of the atmosphere). To achieve equilibrium, the system warms up until it again radiates the same amount of energy as is arriving from the Sun. To give a numerical example, there is about 239 W/m^2 arriving post albedo from the Sun and 239 W/m^2 leaving at the top of the atmosphere. This represents the system in equilibrium (energy in = energy out). If there was a radiative imbalance (or 'radiative forcing') of say 3.7 W/m^2 from a doubling of CO2, the energy leaving at the top of the atmosphere would reduce by 3.7 W/m^2 to 235.3 W/m^2. Currently, there is about 390 W/m^2 emitted by the surface. In this example, an additional 3.7 W/m^2 is received by the surface for a total of 393.7 W/m^2. The +3.7 W/m^2 is responded to the same as the 239 W/m^2 arriving from the Sun and will be amplified by a factor of about 1.6 (390/240 = 1.6), as this is the measurement of the surface response to incident energy. 3.7 W/m^2 x 1.6 = 6 W/m^2 to allow an additional 3.7 W/m^2 to leave the system to restore equilibrium (239 W/m^2 in and out). The new surface emitted radiation would be 396 W/m^2 (390 W/m^2 + 6 W/m^2), which corresponds to about a 1 C rise in temperature. Does this explain it better?
88314. Dikran Marsupial at 04:33 AM on 17 April 2011
       What was it like the last time CO2 levels were this high?
       Giles@28 It is not as simple as whether CO2 is a control or a response. It is one part of the wider climate system, and it both influences responds to the other components, generally CO2 tends to respond rather than to initiate; but there have been occasions when CO2 has driven climate change. For instance the emergence from the Snowball Earth is hard to explain without the accumulated CO2 emissions from volcanic activity. The position of the continents can also affect climate by changing rates of chemical weathering (hence changing CO2 levels), which is an example of CO2 initiating a change in climate. I remember reading an interesting paper in Nature about a period of cooling caused by increased weathering as a result of the uplift of the Appalacians (sorry can't find reference at the moment). The Carbon cycle is the key mechanism that has stabilised the Earths climate for millions of years (see this paper). Personally I think calling it a "control" is only really meaningful in a post-industrial setting, because anthropogenic emissions now control the level of CO2 in the atmosphere and hence have a major influence on the climate. Prior to that, the natural carbon cycle acts much more like a thermostat (see Archer book). As to what caused the Pliocene warm period, I don't know, it seems to me unlikely we will even "know" what caused particular paleoclimate events. However, I don't really see the relevance to the discussion. CO2 is a greenhouse gas; its effect on climate is the same, regardless of what caused it to be in the atmosphere. For modern climate, it doesn't matter if the natural response of CO2 to "other causes" is linear or not (I assume you mean natural causes), as we know that the post-industrial rise in CO2 is not a natural phenomenon. This is one of the few things in climatology that we can be sure of. We have circumvented the "natural response" with anthropogenic emissions.
88315. RW1 at 04:32 AM on 17 April 2011
       Clouds provide negative feedback
       Sphaerica (RE: 6), "Citation please" The albedo effect and global warming "Your assumption, however, that clouds must increase albedo is false. Again, read the above post, and other material. Clouds at high altitudes, which are expected to increase with warming, are composed of ice rather than water. These clouds are virtually transparent to visible light and so do not change the earth's albedo. They do, however, absorb in the infrared and so (as does all H2O) act as powerful greenhouse gases (even though they're solid, not gaseous). Similarly, lower (non-ice) clouds at night will trap heat without changing the albedo at all, so timing of development/dissipation is a factor. Along those same lines, clouds in winter (when the angle of incidence is already low, and the surface being shielded by the clouds is likely snow covered) will have no net change (or even a positive change!) in albedo, while still exhibiting GHG effects. So the assumption that clouds will increase albedo is based on an oversimplification which requires considerably more thought, research and observation." My assumption is not that clouds must increase albedo. The point is if clouds operate as a net positive feedback as claimed, and the data doesn't conclusively show that on average they trap more energy than reflect away, the only way clouds could operate as a net positive feedback is through a reduced albedo, which hasn't happened. I am also aware of the various types of clouds and the complexities of each as it relates to potential changes in the energy balance. " ...is to become 16.6 W/m^2 largely through positive cloud feedbacks... Citation, please. I don't know why you say this. If by 3.7 W/m2 you mean the effect of doubling CO2, then with a climate sensitivity of 3˚C (which is the current best estimate), that would translate into 3.7*3 = 11.1 W/m2, not 16.6 W/m2." It takes +16.6 W/m^2 at the surface for a 3 temperature rise. The 3.7 W/m^2 from 2xCO2 is the additional incident energy at the surface. This is then subject to the system gain or system amplification, which is a factor of about 1.6 (390 W/m^2/239 W/m^2). 3.7 W/m^2 x 1.6 = 6 W/m^2, which BTW, is how they are coming up with a 1 C intrinsic rise from 2xCO2, because +6 W/m^2 = +1C from the Stefan-Boltzman law. "...then why doesn't it take more like 1075 W/m^2 ... Your equations are wrong. You are comparing the wrong factors. The equilibrium temperature of a body is that at which it emits the same amount as is being absorbed. Basically, the equilibrium temperature of the earth would be that at which it emits the same amount of energy as absorbed (i.e. absorbs 239 W/m2, then emits 239 W/m2)." I'm aware of this. In simple energy balance terms, it takes about 390 W/m^2 at the surface to allow 239 W/m^2 to leave the system, offsetting the 239 W/m^2 coming in from the Sun. This is the system measured amplification factor of only about 1.6 to surface incident energy. The AGW claim of a 3 rise requires an amplification factor of 4.5 to allow and additional 3.7 W/m^2 incident on the surface to leave the system to restore equilibrium (239 W/m^2 in and out). In short, if it is going to take an additional 16.6 W/m^2 to allow 3.7 W/m^2 to leave the system to restore equilibrium, then why doesn't it take 1075 W/m^2 at the surface to allow the 239 W/m^2 from the Sun to leave the system at initial equilibrium (16.6/3.7 = 4.5; 1075/239 = 4.5)???
88316. grypo at 04:32 AM on 17 April 2011
       Muller Misinformation #3: Al Gore and polar bears
       Where does this story get its roots from? It seems so detailed that you'd Muller would have gotten it from somewhere.
88317. villabolo at 04:26 AM on 17 April 2011
       What was it like the last time CO2 levels were this high?
       @11 Gilles: "Two questions : a) what is the warming rate which mankind is supposed to be unable to adapt ?" Gilles, oh Gilles. Please keep in mind that there is a difference between humanity per se and civilization. James Lovelock, author of the Gaia Hypothesis and believer in CAGW, says that as little as 100 million human beings would survive. It's even possible to say that (micro) civilizations could exist under the condition he foresees. You only need a few tens of thousands to fulfill the definition of civilization. So would you please rephrase your question based on the potential numbers of a reduced population? Even that would be a silly question to ask; a worthy one but silly nonetheless, due to the enormous difficulty (impossibility?) of calculating the techno-social effects on humanity based on X rate of warming. Human beings are much more difficult to predict than warming rates. That's due to psychology, stupidity and (panic based) ingenuity. I hope you're young. You'll get at least part of the answer to your question(s) without any math or even science. Live long and...
88318. JMurphy at 04:18 AM on 17 April 2011
       Video on why record-breaking snow doesn't mean global warming has stopped
       batsvensson wrote : "Is that correctly understood?" Not by me, anyway. What led you to such understanding ?
88319. Dan Moutal at 04:17 AM on 17 April 2011
       How I lived through a carbon tax and survived to tell the tale
       @ Gilles Please go back and re-read my comments, I never said China didn't need the power plants they are building or that there is a significant risk that we can't switch away from FF. But we are getting off topic. It seems that you have already agreed that a carbon tax can work to reduce emissions. That was the whole point of this post. Obviously selling people on short term pain for long-term gain is difficult. No argument from me there. But arguing over The exact details of how large a carbon tax should be, how fast it should ramp up are beyond both of us (neither of us have working economic models at hand). I just pointed to some research done by an economist who spends his time thinking about these issues. If you have links to research that comes to a dramatically different answer then I would be happy to look at them. Otherwise there is not much lest to discuss.
88320. Chris G at 04:15 AM on 17 April 2011
       What was it like the last time CO2 levels were this high?
       Spike25, I would say that the Csank article above is in the same line as earlier Tripati work, but that is not surprising since Tripati is one of the 'et al' authors. Gilles, I think you should step back and model this as a kind of multi-body problem; whenever one thing changes, all things change. The physics which are used to determine that CO2 is a GHG are well understood. More CO2 causes a warming, but it is not the only thing affecting the climate and humans are not the only thing affecting CO2. How much carbon is sequestered is partly a function of climate conditions, but also continental plate subduction plays a role, etc. However, our production of CO2 through industrial (including agriculture) processes is they only thing that has changed significantly in the last 100 years or so. We know it is getting warmer, and that it will continue to do so; the discussion is about how much and how fast. Feedbacks are everything, and the indication from the above article and others is that the feedbacks will largely amplify the base CO2 effect. Climate models predict this, but we know that climate models are incomplete. That is the nature of models. However, the article above is about the system itself, which by definition has all feedbacks in place and fully accounted for. In the Pliocene, the position of the continents, the output from the sun, and the orbital mechanics are largely the same as they are now; so, we should expect a similar thermodynamic equilibrium from a similar atmospheric composition. I also highly recommend Archer's book "Global Warming: Understanding the Forecast". It covers the basics from the interaction of IR with CO2 molecules on up, but it is not too technical for someone with the skills you have demonstrated. I suspect you are just missing a piece or two of the puzzle and that is skewing your understanding.
88321. jorgepeine at 04:00 AM on 17 April 2011
       Muller Misinformation #3: Al Gore and polar bears
       thanks for this very interesting post. it shows how denials operate. I am really surprised at how these people (also Monckton) get audience ...
88322. JMurphy at 03:59 AM on 17 April 2011
       Christy Crock #3: Internal Variability
       Re : the NIPCC. It was set up by Fred Singer and his SEPP organisation (who also dismiss the risks of smoking and ozone delpetion), and backed by the Heartland Institute. Biased, much ? Appeals to those of a certain political persuasion, perhaps ? Trustworthy ? (The answer to the last is 'NO')
88323. batsvensson at 03:59 AM on 17 April 2011
       Video on why record-breaking snow doesn't mean global warming has stopped
       Hence, when temperature increase snowfall will increase around the polar region causing a greater reflective surface and possible off set any further increase in temperature which in turn may trigger and ice age. Is that correctly understood?
88324. batsvensson at 03:50 AM on 17 April 2011
       What was it like the last time CO2 levels were this high?
       "Earth's past history is sending us a strong message" The OP is claiming this as a fact while it is an interpretation of earth's history. What reason do the OP think is talking against this interpretation and why should they be ignored?
       Moderator Response: [DB] Could you rephrase your question a bit more clearly? As written, it is a bit difficult to parse.
88325. michael sweet at 03:38 AM on 17 April 2011
       Muller Misinformation #3: Al Gore and polar bears
       Dr Muller must have missed this newspaper article about a polar bear who swam hundreds of miles looking for ice, and food. The cub disappeared, presumably drowned.
88326. Bob Lacatena at 03:30 AM on 17 April 2011
       Clouds provide negative feedback
       RW1,

       ...if the albedo is NOT decreasing (or has even slightly increased)

       Citation please. Otherwise either case is speculation. Albedo changes due to ice cover change will be measurable and predictable (in extent and effect, if not rate of arrival). Albedo changes due to cloud cover changes to my knowledge are uncertain at best. We'd know more if certain satellites (DSCVR) hadn't been mothballed, or others lost at launch, or unbuilt satellites had been built, but barring all that... all you have is speculation. Your assumption, however, that clouds must increase albedo is false. Again, read the above post, and other material. Clouds at high altitudes, which are expected to increase with warming, are composed of ice rather than water. These clouds are virtually transparent to visible light and so do not change the earth's albedo. They do, however, absorb in the infrared and so (as does all H₂O) act as powerful greenhouse gases (even though they're solid, not gaseous). Similarly, lower (non-ice) clouds at night will trap heat without changing the albedo at all, so timing of development/dissipation is a factor. Along those same lines, clouds in winter (when the angle of incidence is already low, and the surface being shielded by the clouds is likely snow covered) will have no net change (or even a positive change!) in albedo, while still exhibiting GHG effects. So the assumption that clouds will increase albedo is based on an oversimplification which requires considerably more thought, research and observation.

       ...is to become 16.6 W/m^2 largely through positive cloud feedbacks...

       Citation, please. I don't know why you say this. If by 3.7 W/m² you mean the effect of doubling CO₂, then with a climate sensitivity of 3˚C (which is the current best estimate), that would translate into 3.7*3 = 11.1 W/m², not 16.6 W/m².

       ...then why doesn't it take more like 1075 W/m^2 ...

       Your equations are wrong. You are comparing the wrong factors. The equilibrium temperature of a body is that at which it emits the same amount as is being absorbed. Basically, the equilibrium temperature of the earth would be that at which it emits the same amount of energy as absorbed (i.e. absorbs 239 W/m², then emits 239 W/m²). If CO₂ adds the equivalent of 3.7 W/m², then the total amount absorbed by the climate system becomes 239 W/m² + 3.7 W/m² = 242.7 W/m². With expected feedbacks, this would be 239 W/m² + 11.1 W/m² = 250.1 W/m². The question is, what surface temperature (actually, combined ocean/surface/atmospheric temperatures) results in this amount of emission (radiation)? The answer is a total of 3˚C. ...where is all the energy coming from that is supposed to be causing the enhanced warming? Outside of the above discussion, I think a major mistake that you may be making (this is a guess) is to equate water vapor feedback with clouds. While increased water vapor could result in more clouds, this is not necessarily the case, and clouds are not the form in which the main feedback would occur. Increased temperatures would increase the specific humidity... the amount of moisture carried in the air not in the form of clouds (condensation). This would be a proportional increase for every cubic meter of atmosphere, and H₂O is a very powerful greenhouse gas. This would be the main contributor -- water vapor -- to positive feedbacks. Other positive feedbacks would include clouds (of different sorts), reduced snow and ice, natural release of CO₂ and CH₄, as well as others. All total, these would result in 3˚C of warming per doubling of CO₂.
88327. Gilles at 03:11 AM on 17 April 2011
       What was it like the last time CO2 levels were this high?
       Do you mean that there can be spontaneous variability in the CO2/temperature/oceans system even without a injection of CO2 ? interesting -I thought it was impossible. Nevertheless , unless you justify that the warm period in Pliocen was triggered by massive injection of CO2 from volcanic activity, it corresponds to what I'm saying, CO2 is a response, not a driver. The fact that it enters a feedback loop doesn't change the situation, because amplification acts on both - CO2 and temperature - and so conserve the initial ratio. { - snip - long-winded, off-topic overly mathematical derivation of feedback removed - } In other words, if the amplification factor is *not* large, the CO2 responds only linearly to the "other causes" and its relative part in the global temperature change is minor. I know perfectly that you think it is not the case - but that the amplification factor is large and that CO2 plays a major role - but I haven't seen yet a decisive evidence for that, and I like more explanations to justifiy it.
       Moderator Response: [muoncounter] Variability of atmospheric CO2 in geologic history is the subject of numerous other threads. Before you continue theorizing, please familiarize yourself with some basic tenets of geologic processes.

       Your other points(?) are addressed in several sensitivity threads. Rather than merely calling for others to bring you evidence, you might consider engaging in some actual research of your own.

88328. Enginerd at 03:10 AM on 17 April 2011
       Muller Misinformation #3: Al Gore and polar bears
       Thank you for this post. I've enjoyed reading this site for well over a year, and have never commented. But the audacity of Muller's quotes really struck me. If any of my colleagues (at an environmental consulting firm) included obviously fabricated statements and outrageous distortions as part of a lecture or invited speech, we would likely be severely reprimanded or even fired. How does Muller get away with it? Is he emeritus?
88329. les at 02:37 AM on 17 April 2011
       Muller Misinformation #1: confusing Mike's trick with hide the decline
       Somewhat off topic, but I just came across another scientist using "tricks" here. The point is, of course, that's us just how people discuss things.
88330. JMurphy at 02:32 AM on 17 April 2011
       Video on why record-breaking snow doesn't mean global warming has stopped
       Or this, also from 8 years ago : Global Warming Means More Snow For Great Lakes Region From Science Daily And this from 10 years ago : Another point to note is that while continental-scale snow covered extent is expected to retreat in response to global warming, it is not so clear what other aspects of the snow cover may do. Increased precipitation may lead to increased snow accumulation in cold climate regions, while warming will be accompanied by increased frequencies of mixed precipitation and rain-on-snow events which have implications for snowmelt, snow depth and snow density. Documenting and understanding these characteristics requires monitoring with surface-based observations in addition to satellite data. Is Snow Cover Changing in Canada? It's not difficult to find...
88331. Philippe Chantreau at 02:23 AM on 17 April 2011
       Last day to vote for Climate Change Communicator of the Year
       My vote was in long ago.
88332. les at 02:14 AM on 17 April 2011
       Video on why record-breaking snow doesn't mean global warming has stopped
       7 - JMurphy every day an education! Replies like that are what SkS is (should be) all about.
88333. JMurphy at 02:12 AM on 17 April 2011
       Video on why record-breaking snow doesn't mean global warming has stopped
       Or how about this, more directly related, from 8 years ago : Early Warning Signs of Global Warming: Downpours, Heavy Snowfalls, and Flooding From UCSUSA
88334. Ian Forrester at 02:10 AM on 17 April 2011
       Solar Hockey Stick
       Eric, I suggest you read some of the posts at Open Mind to find out why this talk about "cycles" causing the increase in global temperatures is not valid. Global temperature increase is mostly caused by increases in CO2 resulting from the burning of fossil fuels. No matter how often you try and confuse the reality by mentioning ENSO, AMO etc, you will not convince anyone with a good scientific background that you are correct.
       Moderator Response: And everybody please keep any discussion of cycles on the appropriate threads. This thread is about the Sun, so cycling of the Sun's output could be appropriate here, but there are other threads specific to ENSO, etc.
88335. RW1 at 02:08 AM on 17 April 2011
       Clouds provide negative feedback
       The main point I'm getting at here is if the albedo is NOT decreasing (or has even slightly increased) and if incrementally more clouds don't trap more energy than they reflect away, where is the energy coming from that is supposed to be causing the enhanced warming? Also - if, as the AGW theory claims, an additional 3.7 W/m^2 at the surface is to become 16.6 W/m^2 largely through positive cloud feedbacks, then why doesn't it take more like 1075 W/m^2 at the surface to offset the 239 W/m^2 coming in from the Sun (16.6/3.7 = 4.5; 239 x 4.5 = 1075)?? The measured response of the system at the surface to incident energy is only about 1.6 (390 W/m^2/239 W/m^2 = 1.6). Since the atmosphere can't create any energy of its own, COE dictates the remaining difference of about 10.6 W/m^2 (3.7 x 1.6 = 6 W/m^2; 16.6 - 6 = 10.6 W/m^2) can only come from a reduced albedo (i.e. the Sun). So again, where is all the energy coming from that is supposed to be causing the enhanced warming?
88336. JMurphy at 02:05 AM on 17 April 2011
       Video on why record-breaking snow doesn't mean global warming has stopped
       bastsvensson, that was predicted back in the 1930s at least, albeit wrongly trying to explain a different topic : In 1937 [Sir George Clarke Simpson] suggested that, paradoxically, an increase of solar radiation might bring on an ice age. His reasoning was that a rise in the Sun's radiation would warm the equator more than the poles, evaporating more water from the tropics and increasing the rate of the general circulation of the atmosphere. This would bring more snowfall in the higher latitudes, snow that would accumulate into ice sheets. According to Lamb (1977), p. 661, the first to recognize that an ice-free Arctic Ocean would lead to more snow near the ocean (based on observations of 20th century warm years) and that this could lead to onset of glaciation was O.A. Drozdov; the work was not published at once, and Lamb cites a later publication, Drozdov (1966). Also from The Discovery of Global Warming
88337. mspelto at 01:48 AM on 17 April 2011
       Muller Misinformation #3: Al Gore and polar bears
       Muller continues to illustrate he in not a climate change scientist. No wonder I had never heard of him until this year in my 25 years working in the field. He clearly does not reach the level of Al Gore in fact checking. Further what about consideration of other supporting lines of evidence. Say the Pacific Walrus in Alaska where indications from 2007 and 2010 are not good. This is what a scientist approaching the subject in a scientific manner would consider.
88338. Bob Lacatena at 01:46 AM on 17 April 2011
       Clouds provide negative feedback
       2, 3, RW1, I suggest that you read the post here before commenting further. In particular, you'll find that this statement of yours is false:

       The numbers show that clouds reflect more energy away then they trap.

88339. RW1 at 01:35 AM on 17 April 2011
       Clouds provide negative feedback
       These calculations are consistent with general observations - that is cloudy days are usually cooler than sunny days. The opposite would be the case if clouds blocked more energy than they reflect away (cloudy days would be warmer than sunny days). It's true that at night the net effect of clouds tends to warm or slow heat loss, but these calculations are for global averages, so the differences between night and day are already factored in. The only exception to this would be in areas that are permanently snow or ice covered, as I think the reflectivity of clouds is roughly the same as snow and ice, so in these areas the presence of clouds tend to warm by blocking what little surface emitted energy there is.
88340. Bob Lacatena at 01:32 AM on 17 April 2011
       Muller Misinformation #3: Al Gore and polar bears
       What's funny about this, too, is that his argument about polar bears is clearly a bait-and-switch.

       Not a single polar bear has died because of retreating ice.

       First, how could anyone possibly know this, that not a single polar bear has died because...? How could one ever attribute a single polar bear death to retreating ice? Do they have satellites in space that watch every polar bear, to see if any slip, or get trapped on ice floes? Do they have a PDMEM (Polar Bear Death Evaluation Module) which runs on a Cray supercomputer and determines the statistical probability that a satellite-detected polar bear death was, or was not, attributable to retreating ice? But more importantly (Al Gore's actual vague "That’s not good..." comment aside), no one has ever said that climate change would result in an instantaneous and immediate change in Arctic ice, which in turn would quickly devastate the polar bear population. This is a recurring theme in denial, one that bugs me, and one that people should be ready to recognize and dismiss. This is the idea that "if it hasn't happened yet, climate change is not happening, or not bad." Almost all negative effects of climate change are 20 to 50 years in the future, or even beyond that. Any argument which says "hasn't happened" is purposely ignoring the relevant time frames. Sea level discussions often take the same track, as well as effects on crop production. Sea level rises are going to accelerate dramatically. The fact that it doesn't look so bad today is ignoring the problem. Crop production is going to drop for most of the world. The fact that crop yields may temporarily improve in some regions is ignoring the problem. The problem with climate change is that it is a long term thing, with horrible, negative effects in a relatively distant future, but effects which will be impossible to avoid without action in the near future. Everyone should be on constant guard for this. "It hasn't happened" is a strawman argument against a misrepresentation of the problem, meant to distract and confuse.
88341. Gilles at 01:17 AM on 17 April 2011
       What was it like the last time CO2 levels were this high?
       " As I said, if you want to discuss whether temperature is the cause of the post-industrial rise in CO2," But that's not what I'm discussing - I was discussing variations of CO2 in the last millions years: if it's not temperature, what else ?
       Moderator Response: [Dikran Marsupial] On a scale of thousands of years plus, CO2 levels are largely governed by exchanges with the oceans (which depends on a number of factors, including temperature). On longer timescales by the "chemical weathering thermostat". CO2 is also produced by volcanic activity. On shorter timescales, they also vary with internal variability, e.g. ENSO etc. The book by David Archer that I mentioned earlier explains all this in some detail.
88342. HumanityRules at 01:13 AM on 17 April 2011
       Zebras? In Greenland? Really?
       9 DB Thanks for the comments. I'm not denying the basal melt occured just wondering about the mechanism involved. An ice cube in a glass will melt faster if warmer water is used but also if the water is stirred. I couldn't see in the paper where it showed the underlying mechanism for any presumed changes in the summarine melt. I just found this interesting paper from NaturePrecedings 2011 which seems to go some way to answering that question. The intro is illuminating. These authors seem to suggest that estimates of base melt in Rignot and Steffen 2008 are in fact "estimated as a residual from mass balance calculations using ice-flow and ice-thickness data", i.e. they aren't direct measurements. In fact this paper claims to be the first to make direct measurements. I'll just highlight this section towards the end which seems to suggest that it still unclear whether it's warmer waters or circulation changes that are driving changes in submarine melt. "This adds weight to the possibility that the change in Greenland glacier dynamics over the last decade was not simply a result of the warming the Atlantic waters (estimated to be roughly 1 °C10 and hence comparable to the seasonal variation) but also a consequence of the vertical displacement of the Atlantic/Arctic interface due to changes in the large scale ocean circulation." Either way this seems to be a new insight into the science and worth reading. Enjoy. (Here's another version of their work which again seems to highlight the potential role of circulation changes as an alternate (or complementary) driver of submarine warming.)
88343. Gilles at 01:12 AM on 17 April 2011
       How I lived through a carbon tax and survived to tell the tale
       243 Really Dan I'm surprised - why do China build more than one coal power plant per week if they don't need them ? " well yes without a carbon tax they wouldn't." and who will tax them ? It's also surprising that you reckon that there is a real risk that we couldn't replace all FF with renewables after all - which I agree with of course. But telling that, how do you compare it with the risk of CC ?
88344. Eric (skeptic) at 01:08 AM on 17 April 2011
       Solar Hockey Stick
       Ian, your definition of weather is much too narrow since ENSO is partly weather (and partly climate). It is true that ENSO is somewhat cyclical and that it mainly redistributes heat already in the system. But ENSO also changes albedo and outgoing LWR over substantial portions of the earth. The constant small CO2 warming was amplified by favorable El Nino during most of the 90's. That part of the "cycle" will not necessarily be balanced by an opposite phase of the cycle. It can't just be ignored. Another "cycle" that we "skeptics" like to point to is Arctic Oscillation and North Atlantic Oscillation, both currently more negative than positive. Those tie nicely back into this thread since they are partly solar induced. For example the current low solar UV contributes to negative NAO in general and more specific changes in blocking (chart, paper: http://www.agu.org/journals/jd/jd0814/2008JD009789/2008JD009789.pdf) It is an oversimplification to say that those solar changes are "cooling". What they do is modulate weather (to a large extent) which then affects the amplification of CO2 warming or other forcings (to a smaller extent). And again, they are only nominally cyclical (the upcoming low solar maximum may be a part of a cycle from the higher solar cycles of the late 20th century, but solar cycles of century time scales are impossible to predict)
88345. Gilles at 00:51 AM on 17 April 2011
       Christy Crock #3: Internal Variability
       DM : are you arguing that it's wrong to say that GCM models were easily prone to secular drifts, or did I misunderstand you ? Mucounter :"< it is a process of eliminating the improbables from consideration." Precisely - that's why you have to demonstrate carefully that the other alternatives are improbable, and that we're totally entitled to ask you the justification - do we agree that saying "I can reproduce what I see with my hypothesis" , and even "I cannot reproduce what I see with my computer simulation" is far from being sufficient to say that ?
       Moderator Response: [Dikran Marsupial] I intended to suggest you should provide evidence to back up your assertion if you want to discuss that.
88346. Gilles at 00:46 AM on 17 April 2011
       What was it like the last time CO2 levels were this high?
       " It is not correct that all unfalsified hypotheses are equally plausible." Maybe , but you have to prove they're not equally plausible - and there is evidence that at some times in the last million of year , a decrease of CO2 lagged a decrease of temperature. "If you are claiming that rising temperature increases CO2," well please let me know what else could increase CO2 ! and I'm precisely arguing this is relevant to this topics, because you have to disentangle which is the cause of which.
       Moderator Response: [Dikran Marsupial] As I said, if you want to discuss whether temperature is the cause of the post-industrial rise in CO2, or vice versa, please do it elsewhere, it is off-topic here. If you raise this topic again on this thread, the post will be deleted, you have been warned. This is not censorship, you are welcome to discuss it on a more appropriate thread.

       This thread would be particularly appropriate.

88347. batsvensson at 00:35 AM on 17 April 2011
       Video on why record-breaking snow doesn't mean global warming has stopped
       Did any one propose, say, 10 years ago that snowing will increase when the climate warms up?
88348. Ken Lambert at 00:31 AM on 17 April 2011
       The e-mail 'scandal' travesty in misquoting Trenberth on
       Alec Cowan #125 "The rest are your numbers, which you won't reply if contested. You still have to answer for your calculations in #116. You wouldn't answer to the obvious bait I placed in front of you, because to do so you had to admit that you were changing the black body temperature of Earth. What did you have in mind? Tunning up the Sun? Moving the Planet 2 million kilometers closer to the Sun? Growing Earth's diameter?" Alec my reply was deleted by Moderators. You have to be quick and online to see my replies these days. Offer your own calculation instead of 'baiting' us with your commentary.
       Moderator Response:

       [DB] As you well know, comments constructed to adhere to the Comments Policy which are also on-topic are never deleted. In any case, your deleted reply to Alec is here:

       Ken Lambert at 12:29 PM on 16 April 2011

       Alec Cowan #118

       "We're still talking about Earth, aren't we? Please, confirm that and your 255°K. Imagine the surprise of 15 degrees Celsius plus 240 watts per sq. meter becoming 255 degrees Kelvin and then being "remarkably close" to something slightly pertinent to the subject."

       I assume you are taking the mickey here Alec. Respond with something showing some understanding of the numbers or take your 5 year old computer and go home.

88349. logicman at 00:29 AM on 17 April 2011
       It warmed just as fast in 1860-1880 and 1910-1940
       #104 - Adam My trollometer just went off the scale! Adam, you say: "I just wanted to point out to you that Phil Jones himself has confirmed that the three periods of warming were indeed exactly parallel to each other." What a world of difference there is between 'exactly parallel' and what Phil Jones actually said: "the warming rates for all 4 periods are similar and not statistically significantly different from each other." http://news.bbc.co.uk/1/hi/sci/tech/8511670.stm I find it strange that somebody would state what Phil Jones said, and then proceed to post a proof that he did not say it!
       Moderator Response: [Dikran Marsupial] Unless, like many, Adam doesn't understand what statistical (in-)significance actually means.
88350. RW1 at 00:23 AM on 17 April 2011
       Clouds provide negative feedback
       It was suggested I move this discussion to this thread. The numbers show that clouds reflect more energy away then they trap. Given that the albedo has not been decreasing, and if anything has even increased slightly, this is completely inconsistent with clouds operating as a net positive feedback. Here are the numbers on how much incrementally more clouds reflect, according to Trenberth et al 2009: Clouds cover about 2/3rds of the surface, so 341 W/m^2 x 0.67 = 228 W/m^2 average incident on the clouds. 79 W/m^2 divided by 228 W/m^2 = 0.34 average reflectivity of clouds. 1/3rd of the surface is cloudless, so 341 W/m^2 x 0.33 = 113 W/m^2 average incident on the cloudless surface. 23 W/m^2 divided by 113 W/m^2 = 0.20 average reflectivity of the cloudless surface. 0.34 - 0.20 = 0.14. 341 W/m^2 x 0.14 = 48 W/m^2 loss for each additional m^2 of cloud cover. Here are the numbers on how much incrementally more clouds trap: The cloudy sky has a transmittance of 30 W/m^2, and the surface emitted through the cloudy sky is about 265 W/m^2 (396 x 0.67 = 265). 265 W/m^2 - 30 W/m^2 = 235 W/m^2 absorbed by the cloudy sky. The clear sky has a transmittance of 40 W/m^2, and the surface emitted through the clear sky is 131 W/m^2 (396 x 0.33 = 131). 131 W/m^2 - 40 W/m^2 = 91 W/m^2 absorbed by the clear sky. 91 W/m^2 divided by 131 W/m^2 = 0.69; 235 W/m^2 divided by 265 W/m^2 = 0.89. 0.89 - 0.69 = 0.20 difference between the cloudy and clear sky. 0.20 x 396 W/m^2 = 79 W/m^2 additional absorbed for each additional m^2 of cloud cover. If we assume that roughly half of the absorption and re-emission is back toward the surface (Trenberth actually has this being less than half), that comes to about 39 W/m^2, or about 10 W/m^2 less than the 48 W/m^2 reflected away. *If anyone doubts my calculations, I have backed check them by assuming that if half of the absorption is directed up out to space, then the weighted average totals should correspond to a temperature of about 255K. 0.69/2 (absorbed clear sky) + 0.31 passing through the clear sky = 0.66 and 0.89/2 (absorbed cloudy sky) + 0.11 passing through the cloudy sky = 0.55; 0.66 x 0.33 (clear sky) = 0.22 and 0.55 x 0.67 (cloudy sky) = 0.37; 0.22 + 0.37 = 0.59 emitted to space from the surface; 396 W/m^2 x 0.59 = 234 W/m^2 (about 254K), which is pretty close. *The missing 5 W/m^2 is probably due to Trenberth having greater than 50% of the atmospheric absorption being emitted up out to space.

Prev  1759  1760  1761  1762  1763  1764  1765  1766  1767  1768  1769  1770  1771  1772  1773  1774  Next