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RW1 at 03:54 AM on 24 January 2011Oceans are cooling
muoncounter, "That is a standard high school physics demonstration. I promise you the back side of the brick stays much cooler than the rapidly heated side." Can you direct me to a source that shows or documents this demonstration? I guess it would depend on the size and makeup of the brick, as well as the amount of and duration of heating/cooling, etc. -
Dikran Marsupial at 03:52 AM on 24 January 2011Monckton Myth #4: Climate Sensitivity
RW1@34 Yes, that is the one I found, and they use the AMIP models, so they haven't addressed the criticisms levelled at Lindzen and Choi (2009). The SSTs in the AMIP models are forced from the observations, which means that the system no longer conserves energy; hence any argument that is based on energy budget will be invalid. Lindzen argues that only the AMIP models have the same SSTs as the ERBE obeservations, but so what? The assumption of conservation of energy is broken so the argument is invalid. This error was pointed out to them. Also isn't this paper from the procedings of a symposium, and hence (a) it was lightly peer reviewed (if at all) and (b) there is no mechanism for formal comments papers like there would be for a journal paper (c) it is very recent, which means that it hasn't been scrutinised by the research community yet (a good way of telling if a paper is any good is to look at its citations, if nobody cites it, it is generally because it is either uninteresting or incorrect). -
muoncounter at 03:36 AM on 24 January 2011Oceans are cooling
#48: "the whole brick would warm and cool" That is a standard high school physics demonstration. I promise you the back side of the brick stays much cooler than the rapidly heated side. "What is the physical reason? If the whole ocean participated in the thermal mass, the short term seasonal warming could not occur." Let's lose the hypothetical nature of this question and start with the observation that seasonal warming and cooling does indeed occur. We certainly can agree that ocean surface layers therefore act as if they have low thermal inertia and participate in these relative rapid changes. As to the greater inertia question, do you agree with the analysis presented by NOAA here? The seasonal variations in heating penetrate into the ocean through a combination of radiation, convective overturning (in which cooled surface waters sink while warmer more buoyant waters below rise) and mechanical stirring by winds. There are your mechanisms. ... These processes mix heat through the mixed layer, which, on average, involves about the upper 90 m of ocean. The thermal inertia of a 90 m layer can add a delay of about 6 years to the temperature response to an instantaneous change ... As a result, actual changes in climate tend to be gradual. There is the reason why 'the tiny little increase from CO2' does not change the ocean temperature quickly. With its mean depth of about 3800 m, the total ocean would add a delay of 230 years to the response if rapidly mixed. However, mixing is not a rapid process for most of the ocean ... An overall estimate of the delay in surface temperature response caused by the oceans is 10–100 years. --emphasis added All of that inertia, without any discussion of the complicating roles of density layering and thermocline structure. Salinity effects on ocean density are also important but are poorly measured at present. It is essential to be able to attribute changes in ocean heat content and the mass of the ocean to causes (such as changing atmospheric composition), perhaps using models. Climate models suggest that the THC could slow down as global warming progresses, resulting in counter-intuitive relative regional cooling or, more likely, reduced warming on multi-decadal time-scales. -
Camburn at 03:29 AM on 24 January 2011The Climate Show #5: Green roofs and Brisbane floods
Albatross@14: My skepticism of the validity of SSM/I is a result of finding the on ground measurements verses the SSM/I indications. I am most interested in Argentina/Brazil as weather patterns in that area directly affect my business. I do not take a single rain guage as verification. It is quit easy to find various rain guages that verify or refute what the satillite is showing at a certain time. This indicates to me that the satillite measurements/data are not reliable metrics. Radar for sure is an unreliable metric of actual measured precipitation. I have read several papers concerning precipitation events/trends etc. One thing I have noted is the seemingly absense of error bars in the papers. It is very hard to draw conclusions without those present. My experience would indicate that the SSM/I error bars should be relatively large, but without the underlying data it is impossible for me to create them. This type of science is extremely important to me in making sound business decissions and I can only hope it becomes more precise in the future. Thank you for the links presented. -
RW1 at 03:13 AM on 24 January 2011Monckton Myth #4: Climate Sensitivity
Dikran (RE: 33), Lindzen2010 -
RW1 at 03:01 AM on 24 January 2011Oceans are cooling
KR, "The top of the brick will alternately be hot enough to burn your hand and cold enough for a nice iced drink." I wouldn't think so - I think the whole brick would warm and cool, but a pot of water would be more analogous to use. That's not going to work either though, I don't think. "Only the upper layer of the ocean gets seriously involved in short term seasonal temperture/insolation variations, and since it's a fairly small mass it changes quite a lot. But a constant offset? That has time to sink in, to change the deep ocean. And hence the average temperature of the oceans." Why? What is the physical reason? If the whole ocean participated in the thermal mass, the short term seasonal warming could not occur. There is no reason to believe the tiny little increase from CO2 wouldn't also change the ocean surface temperature just a quickly. The question is equilibrium time per incremental amount of forcing - not whether or not gradual changes in the upper ocean layers can eventually trickle to the deep ocean waters somewhat. There are also many reasons why the temps of deep ocean waters can change. -
Dikran Marsupial at 02:58 AM on 24 January 2011Monckton Myth #4: Climate Sensitivity
RW1@31 Can you give a specific reference for Lindzen 2010? The only one I could find appears to be still using AMIP models and hence does not address one of the key criticisms of Lindzen and Choi (2009). -
Eric (skeptic) at 02:55 AM on 24 January 2011Arctic sea ice has recovered
Riccardo, I will keep that in mind. The LIA was stuck in my mind because I wanted to caveat the record low in sea ice by saying post-LIA. But I actually do not have any evidence in hand that sea ice was lower before the LIA (e.g. MWP), so I should have left that out entirely. -
angliss at 02:51 AM on 24 January 2011Oceans are cooling
You can prove that there is heating in the pipeline, as it were, by using a simple capacitance relationship: I = C * dV/dt, where C is the heat capacity of a block of ocean, dV is the change in temperature, I is the amount of power injected into the block of ocean, and dt is the time it takes to heat up the amount dV. Note that I used electrical terminology because of my EE background, but the math is the same. Rearrange the terms to solve for dt and then do a little digging for the heat capacity of a block of seawater, and ta-da, you've got your first-order approximation of the answer. It neglects seasonal variations, convection, and radiation, and heat conductivity so it's hardly perfect, but it's a good starting point. Add heat conductivity and the time goes up. Add convection and radiation and the time drops. Add seasonal variation and the time shouldn't change much if at all. -
Eric (skeptic) at 02:49 AM on 24 January 2011Monckton Myth #4: Climate Sensitivity
Ken, considering that some models predict more positive AO http://www.cccma.ec.gc.ca/papers/jfyfe/PDF/FyfeBoerFlato1999a.pdf and some say more negative due to ice loss http://journals.ametsoc.org/doi/pdf/10.1175/1520-0442%282004%29017%3C0890%3ATARTRA%3E2.0.CO%3B2 the AO response is a prime example of a climate change paradox: http://www.agu.org/pubs/crossref/2005.../2004GL021752.shtml Natural variations in albedo are over 10% in summer in the Arctic alone https://www.cfa.harvard.edu/~wsoon/MattCronin-Mar21-07-d/WangKey03-ArcticClds+TfromAVHRR.pdf strongly correlated with AO. It is even more difficult to predict the cloud and albedo changes in the NH land masses without knowing the AO sign. I have to ask the question: what is the solution to this prediction problem? Assume the models are correct and AO will become positive? Assume it will become negative in early winter due to ice loss and add that feature to the models? Assume it varies randomly and add random variation to the models? -
RW1 at 02:39 AM on 24 January 2011Monckton Myth #4: Climate Sensitivity
People keep referencing Lindzen 2009, but they addressed the criticisms and largely re-did the whole thing in Lindzen 2010 and the end result was pretty much the same. -
michael sweet at 02:34 AM on 24 January 2011Monckton Myth #6: Global Sea Ice
Galloping Camel: Since the most recent IPCC report was issued BEFORE the sea ice low in 2007, it is impossible for them to be alarmist about the sea ice low that year. Denialists, on the other hand, frequently make alarmist statements. Your claim in 29 shows that you do not care about the facts of the situation. Please stop making such absurd claims. -
JMurphy at 00:42 AM on 24 January 2011Medieval Warm Period was warmer
hengistmcstone, there are a few studies here, here, and here, which go back to about 11000 years ago. -
hengistmcstone at 23:48 PM on 23 January 2011Medieval Warm Period was warmer
Hi, "the Medieval Warm Period occurred during a time which had higher than average solar radiation and less volcanic activity" I don't see how the first argument there 'a time which had higher than average solar radiation' can stand on it's own. What measurements do we have for solar irradiance 500 years ago? Can you please cite some papers in support. Thx Hengist -
Ken Lambert at 23:32 PM on 23 January 2011Monckton Myth #4: Climate Sensitivity
Eric #29 How about we try to put some numbers on cloud and direct albedo going forward. The TSI (divided by 4)is about 340W/sq.m at TOA and total reflection (cloud and direct albedo) is quoted as about 100W/sq.m (30%) leaving about 240W/sq.m energy flux to play in the biosphere. AGW theory says that there is an average 0.9W/sq.m positive warming imbalance which means that for a net 240W/sq.m incoming, 239.1W/sq.m goes out. How accuragely do we measure the roughly 100W/sq.m ie; 30% reflected? How do we project that measurement forward to cycle models? eg; let us assume that the 30% is measures to +/-1% accuracy; therfore it could be 30.3% or 29.7%. In real terms 101W/sq.m or 99W/sq.m. This example tolerance +/-1W/sq.m is higher than the imbalance (0.9W/sq.m) postulated. Are we measuring these numbers to that accuracy and how would these vary in a higher WV or higher CO2 environment for input to climate models?? -
Riccardo at 23:23 PM on 23 January 2011Arctic sea ice has recovered
Eric (skeptic) sorry for being OT and a bit pedantic. Given that your comments are usually scientifically well reasoned, I'd like to suggest to not use the term "recovery from LIA". This term implies a planet that for some reason was pushed out of a well defined equilibrium and is now going back toward the previous (or any other) equilibrium. In reality, as I'm sure you'll agree, the forcings has changed, and are still changing for whatever reason, and the planet is changing accordingly. -
Eric (skeptic) at 22:12 PM on 23 January 2011Arctic sea ice has recovered
Overland has a more recent paper http://onlinelibrary.wiley.com/doi/10.1002/joc.1973/abstract attributing the 1920-1940 Arctic warming as partly AGW: "Our findings indicate that early climatic fluctuation is best interpreted as a large but random climate excursion imposed on top of the steadily rising global mean temperature associated with anthropogenic forcing." -
Eric (skeptic) at 21:57 PM on 23 January 2011Arctic sea ice has recovered
Let me first answer the overt question of the thread: Has Arctic sea ice returned to normal? No, it is still near record lows for the post-Little-Ice-Age period. But there is also a covert question in this thread that came up in the thread linked by Muoncounter above. That question is: Has Arctic sea ice fluctuated in the past (i.e. what is normal)? The Walsh data that muoncounter provided is flat mainly because it is out of date. It doesn't include the Russian data http://nsidc.org/data/g02176.html) For example, the dip in the 30's is nonexistent. There are natural explanations for such dips, for example http://www.agu.org/pubs/crossref/2005/2005GL024254.shtml "The period from 1928–1935 also had a dipole structure in SLP, which contributed to the interdecadal arctic-wide warm temperature anomalies in the first half of the 20th century." Also as I pointed out in the other thread, the main cause of late 19th and early 20th century decline in both hemispheres was recovery from the LIA. The main cause of the current, abrupt decline is AGW plus local feedback from open ocean. I am not trying to hide anything. -
michael sweet at 20:49 PM on 23 January 2011Arctic sea ice has recovered
Responding to Galloping Camel on the Monckton thread who wants to throw away the data: The data set that Muoncounter cited says the data is reliable back to 1953. I figure that is 60 years, not 40. The additional data back to 1900 can be used carefully. Scientists use all the available data to reach the most comprehensive conclusions. It is typical of "skeptics" to deny data that has been carefully gathered because it shows that AGW is much worse. People live in the Arctic and they record the conditions where they live. Explorers kept careful records of ice conditions where they were. Fishermen record the ice edge (watch Deadliest Catch). These records enable comparisions to current data. Cite a reference that says the graphs I have copied are not usable or stop your unscientific comments. It was not my intention to suggest that the ice was flat in the past. The data shows that the ice has been in significant decline because of AGW for longer than the 30 year satelite record. Deniers want to limit the data used to hide the decline in Arctic sea ice. -
scaddenp at 20:45 PM on 23 January 2011Global Warming and Cold Winters
"Climate change can be very sudden" - yep. Broecker commented too that climate change that rapid would destroy temperature food production in NH as how would farmers know what to plant? However, these very rapid reversals only appear in the historical record when coming out of a glacial. If there was a risk of such an event due to current climate behaviour then we would be in a grave position indeed but there is little evidence for such a risk. There may be more than one cause for YD-type, Heinrich events and such like but none of theories suggest a risk that would operate now. -
gallopingcamel at 17:59 PM on 23 January 2011Monckton Myth #6: Global Sea Ice
Accurate measurement of sea ice extent has been available for less than 40 years so we don't yet know what the "normal" range of variations is. However this thread does at least admit that Antarctic ice cover has been increasing over that brief period while Arctic ice has trended downwards. Those folks (e.g. the IPCC and the NSIDC) who predicted a dramatic decrease in Arctic ice by assuming that the trend that gave us a record low ice coverage in 2007 would continue have been shown to be wrong (color them "Alarmists"). Here is some information on Arctic ice in a region that has some economic importance (at least to the Russians): http://diggingintheclay.wordpress.com/2011/01/09/ice-build-up-in-sea-of-okhotsk/Response: Actually, the IPCC grossly underestimated the decrease in Arctic sea ice:
In this case, the "alarmist" is nature itself which reacted more strongly than even the IPCC's worst case scenario. -
Oceans are cooling
RW1 - "Neither will the top of the brick." Really? The top of the brick will alternately be hot enough to burn your hand and cold enough for a nice iced drink. As to why a brick - I thought that a simpler case for discussing slow thermal transfer from top to bottom. Only the upper layer of the ocean gets seriously involved in short term seasonal temperture/insolation variations, and since it's a fairly small mass it changes quite a lot. But a constant offset? That has time to sink in, to change the deep ocean. And hence the average temperature of the oceans. I'm beginning to find your objections to this disingenuous... -
RW1 at 16:31 PM on 23 January 2011Oceans are cooling
KR, Also, why are you analogizing with a brick rather than a pot of water? -
dhogaza at 16:29 PM on 23 January 2011A Case Study in Climate Science Integrity
Ron Crouch:If governments would only face global warming with the same tenacity that they apply to terrorism.
Actually, the current leadership of the Republican Party in the US does ... Problem being they look at climate science as being equivalent to terrorism ... -
dhogaza at 16:27 PM on 23 January 2011Monckton Myth #6: Global Sea Ice
muoncounter: I responded to Eric before reading your request to move discussion to an earlier thread ... -
dhogaza at 16:25 PM on 23 January 2011Monckton Myth #6: Global Sea Ice
" I think flat linear is not a good fit at least for maximum ice extent (perhaps better for minimum) because of harsher winters up to the end of the Little Ice Age." So everybody take care that I explicitly mentioned the last two graphs of Eric's first post (June and August), and he responded by plotting April. We all know that the maximum winter extent tends to be geographically bounded in the Arctic, which is why the most attention is paid to the September minimums. "it is a smaller area and it is the max extent and it ends before 2000, so obviously a lot less of a drop. You are correct that the AGW variations show up in the min extent more. The point of the chart is to show the natural variation." Well, at least you admit to cherry-picking. Why on earth you think this will add to your credibility here is beyond me. -
RW1 at 16:09 PM on 23 January 2011Oceans are cooling
KR, "If I take a brick and repeatedly pass a hot torch and a block of ice over the top of it, the bottom of the brick will change temperature almost not at all." Neither will the top of the brick. -
Oceans are cooling
RW1 - You are still not looking at this from a standpoint of penetration depth. Given the thermal conductivity and circulation patterns of the oceans, it takes time for heat to reach the deep ocean, and hence short term seasonal variations do not penetrate very far into the ocean mass. The total mass changing temperatures up and down is a relatively small portion of the ocean thermal mass. A constant offset, on the other hand (like the current energy imbalance) held over what is now multiple decades - that has time to affect deep waters, and affect the average temperatures. If I take a brick and repeatedly pass a hot torch and a block of ice over the top of it, the bottom of the brick will change temperature almost not at all. If, on the other hand, I sit an electric blanket on it all day, the bottom of the brick will warm up. Penetration depth, and time for heat transfer! -
Ron Crouch at 15:31 PM on 23 January 2011A Case Study in Climate Science Integrity
#42 Tom Yeah. I know that was your point. Sorry if it sounded as if my frustrations were directed specifically at your comment. If governments would only face global warming with the same tenacity that they apply to terrorism. -
MikeCoombes at 15:26 PM on 23 January 2011Monckton Myth #6: Global Sea Ice
Tom Curtis@13 I think you misread the intent of the comment and I was too much in professor mode. I am always telling my students that a single number by itself is not the basis for a conclusion and that they should not expect me to dig through the rest of their lab report for the data that backs them up. The sentence is saying that a million is a big number so that it is big effect. It is the converse of the the argument that 350 ppm of CO2 is a small number and so can only have a small effect on climate. Neither is a scientific argument. Big and small are relative terms and need other numbers for context. Simply adding that the decline is in fact a 5% long term decrease will greatly increase the chances that a reader will agree that Monckton is an ass. I hasten to add that I don't think James Wright is trying to pull a fast one. He has done a great job and presented lots of evidence but the intro could still use a few tweaks. I hope he sees my comment as a friendly suggestion. -
RW1 at 15:20 PM on 23 January 2011Oceans are cooling
Robert S (RE: 41), "Ah, I wondered if this was your issue. Nonlinear, RW1, Nonlinear. As the Earth warms, the more it emits (a la Stefan-Boltzmann), the less the imbalance becomes = less energy builds up in the system per unit time. Temperature will follow a roughly logarithmic curve with a horizontal asymptote at the new equilibrium temperature." Some of the nonlinearity was factored in because it's not +100 W/m^2 for the whole 6 months. OK, how should we calculate the non linear response given these knowns (+10C surface air and about 5 C ocean)? Let's run the numbers - it still isn't going to be anywhere near a decade. -
Steve Meacher at 15:19 PM on 23 January 2011The Climate Show #5: Green roofs and Brisbane floods
# Daniel Bailey (2) I've had another look at Leif's original calculation. He was actually not looking at total increased water vapour in the atmosphere (as John is) but at increased total precipitation over land. Although I disagree with some of the details of his calculation, I reckon his result is about right. I get around 1.6 "Lake Superiors" additional precipitation over land, globally. Given recent media statements that twice the volume of Sydney harbour was flowing daily through Wivenhoe Dam, I thought it might be interesting to estimate how many extra "Sydney harbours" of rainfall Australia might expect. Based on 1989 rainfall (BoM) of 3,713 cubic kms. an increase in precipitation of 4% translates to an extra 267 Sydney harbours falling across Australia each year. -
RobertS at 15:04 PM on 23 January 2011Oceans are cooling
"If the equilibrium response time were a decade, then we should expect at least an accumulation of over 20 C a year air and about 10 C ocean, correct? Over ten years, that amounts to over 200 C air and 100 C ocean." Ah, I wondered if this was your issue. Nonlinear, RW1, Nonlinear. As the Earth warms, the more it emits (a la Stefan-Boltzmann), the less the imbalance becomes = less energy builds up in the system per unit time. Temperature will follow a roughly logarithmic curve with a horizontal asymptote at the new equilibrium temperature. "This is interesting. I though the AGW theory is saying the opposite of this - that is most of the warming is in the pipeline and yet to occur?" No - ~0.8C seen so far, ~0.6 to go. But this issue is complicated by other forcings and a gradual (but increasing) buildup of CO2. That's why I gave the hypothetical Earth example to simplify things. -
muoncounter at 14:27 PM on 23 January 2011Arctic sea ice has recovered
Continuing from here, comment #23. "the 30's to 50's drop from very large extents to less large is only a bit less in magnitude." No, the '30s to '50s drop is a lot less in magnitude. Here is a graph of the Walsh data set, txt file here. Red is September min, blue is March max.
Perhaps the variations reported by Mahoney et al 2008 in the Russian arctic are the mid-century blips. By way of contrast, we're on the downward Nantucket sleigh ride.
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muoncounter at 14:18 PM on 23 January 2011Monckton Myth #6: Global Sea Ice
#23: We're now well away from the original topic of this thread. Continuing ice discussion on the Sea ice has recovered thread. -
Eric (skeptic) at 14:17 PM on 23 January 2011Monckton Myth #6: Global Sea Ice
For the Antarctic, there is some historical discussion here http://www.igsoc.org/annals/1/igs_annals_vol01_year1980_pg103-112.pdf but not ice extent data, just "considerably greater" numbers of icebergs in the late 1800's than the 1970's. -
Eric (skeptic) at 14:13 PM on 23 January 2011Oceans are cooling
RW1, please look at the paper I linked in #31 which gives an estimate of the seasonal ocean heat storage (5×1022 J trough to peak). Then compare that to the seasonal increase in TSI (need to integrate the increased power over the same portion of the year). Unfortunately I do not have the numbers to do that. Then compare the two and see how much of the extra solar energy made it into the ocean in one season. -
RW1 at 13:56 PM on 23 January 2011Oceans are cooling
Robert S., "On a hypothetical Earth where we instantly doubled the CO2 from 280ppm to 560ppm, the bulk of the temperature change would indeed be felt within the first few years, but full equilibrium is not reached for a century or longer according to climate commitment studies (try Meehl 2005" This is interesting. I though the AGW theory is saying the opposite of this - that is most of the warming is in the pipeline and yet to occur? -
Eric (skeptic) at 13:45 PM on 23 January 2011Monckton Myth #6: Global Sea Ice
The Russian data shows that a drop about 30% larger from the early 80's to 2005 compared to the drop from the 30's to the 50's. The data covers less than 1/2 of the Arctic, but the temperature change is representative of the Arctic as a whole (Fig 9 in the link #21). The Walsh and Johnson paper shows just a small rise from 53-77 which is proportionally less than the Russian data. It might be more representative of that time period but unfortunately doesn't go earlier. I am convinced the current drop is dramatic and the current extent was made much smaller due to feedbacks from prior season open water and late refreezing. The issue is that the 30's to 50's drop from very large extents to less large is only a bit less in magnitude. -
RW1 at 13:45 PM on 23 January 2011A Case Study in Climate Science Integrity
Robert, I responded in the ocean/heating cooling thread. -
RW1 at 13:44 PM on 23 January 2011Oceans are cooling
Continued from another thread: Robert S., "No one is claiming that. The fact that there are large seasonal temperature variations in no way contradicts a long equilibrium time. With seasons we are not talking about equilibrium time because, as Tom says, the hemispheres do not reach equilibrium with the max and min values of insolation and albedo. No where even close." OK, let's run some numbers. The northern hemisphere surface air temperature increase at peak summer is over 10 C on average. The sea surface temperature increase is about 5 C. This is an enormous accumulation of heat in a very short period of time - only 6 months, during which only part of the +100 W/m^2 peak solar energy is forcing the hemisphere. Let's say hypothetically speaking, the earth were to suddenly remain at its maximum summer tilt angle permanently. If the equilibrium response time were a decade, then we should expect at least an accumulation of over 20 C a year air and about 10 C ocean, correct? Over ten years, that amounts to over 200 C air and 100 C ocean. That is obviously way too high, don't you think? Let's shorten the time span to only 2 years. That would still amount to over 40 C air and 20 C ocean. That still seems too high, doesn't it? -
muoncounter at 13:30 PM on 23 January 2011Arctic sea ice has recovered
Hits just keep on coming. Reduced ice extent decreases the albedo, which in turn reduces the negative feedback (and that increases the net positive forcing, no?) Flanner et al 2011: Radiative forcing and albedo feedback from the Northern Hemisphere cryosphere between 1979 and 2008 We find that cryospheric cooling declined by 0.45 W m−2 from 1979 to 2008, with nearly equal contributions from changes in land snow cover and sea ice. On the basis of these observations, we conclude that the albedo feedback from the Northern Hemisphere cryosphere falls between 0.3 and 1.1 W m−2 K−1, substantially larger than comparable estimates obtained from 18 climate models. -
muoncounter at 13:04 PM on 23 January 2011Monckton Myth #6: Global Sea Ice
#21: "point of the chart is to show the natural variation." Which it shows very well. The natural variation is tiny compared to the unnatural change. Here's one of the papers from the link I gave in #20: Walsh and Johnson 1979: Arctic sea ice data from the 1953–77 period are digitized onto a set of 300 monthly grids covering the polar cap. ... The time series of total Arctic ice extent shows a statistically significant positive trend and correlates negatively with recent high-latitude temperature fluctuations. I don't know the magnitude of the 'significant positive trend,' but the title of this paper includes the word 'fluctuations'. See the graph here. The mere existence of fluctuations is to be expected -- note that in subsequent literature the word 'fluctuation' is replaced by words like 'collapse'. -
Eric (skeptic) at 12:30 PM on 23 January 2011Monckton Myth #6: Global Sea Ice
#20 muoncounter, it is a smaller area and it is the max extent and it ends before 2000, so obviously a lot less of a drop. You are correct that the AGW variations show up in the min extent more. The point of the chart is to show the natural variation. Here's the Russian data analyzed in a study http://seaice.alaska.edu/gi/publications/mahoney/Mahoney_2008_JGR_20thC_RSI.pdf Unfortunately it only starts in 1933 and then only in summer (defined as Jul-Sep). Figure 8 it shows the summer ice extent dropping into the early 50's, then a slight rise to the early 80's and then dropping more steeply to the end of the study 2005/6. Once again a limited area so the drops are scaled correspondingly, about 1/2 million sq km from the 1930's to the 1950's and a bit more than that from the early 80's to 2005. -
RobertS at 12:29 PM on 23 January 2011A Case Study in Climate Science Integrity
Should be ...because of the massive difference between absorbed solar in winter vs. summer. Any further discussion will be in the ocean heating/cooling thread. -
RobertS at 12:23 PM on 23 January 2011A Case Study in Climate Science Integrity
"In effect, what's being claimed here is that the far smaller imbalance from CO2 will take way longer to reach equilibrium than the much larger seasonal imbalance from the Sun, and that doesn't add up." No one is claiming that. The fact that there are large seasonal temperature variations in no way contradicts a long equilibrium time. With seasons we are not talking about equilibrium time because, as Tom says, the hemispheres do not reach equilibrium with the max and min values of insolation and albedo. No where even close. The hemispheres don't need to reach equilibrium (or anywhere even close) for such large temperature variations to be observed because of the massive difference between absorbed solar in winter vs. solar. On a hypothetical Earth where we instantly doubled the CO2 from 280ppm to 560ppm, the bulk of the temperature change would indeed be felt within the first few years, but full equilibrium is not reached for a century or longer according to climate commitment studies (try Meehl 2005). A larger forcing, like what is seen hemispherically with the seasons, will take even longer to equilibrate, with the initial temperature change over the first year being considerably larger than what is seen in the doubled CO2 case. -
muoncounter at 12:19 PM on 23 January 2011Monckton Myth #6: Global Sea Ice
#19: "a natural decline in maximum extent prior to recent AGW-related declines" Eric, the scale of your max extent graph in #19 shows a drop (the curve labeled NS) of less than 1 million sq km. The scale on the graph in #2 has the winter curve at 15-16 million sq km. So the pre-AGW variations you're talking about would appear on the scale of the noise on the large scale graph. You should also be looking for minimum ice extents (usually September). There are reconstructed data sets available. -
RW1 at 12:08 PM on 23 January 2011A Case Study in Climate Science Integrity
Moderator, OK, we'll take it over there. -
RW1 at 11:59 AM on 23 January 2011A Case Study in Climate Science Integrity
Robert S. (RE: 45), "During the winter (in either hemisphere) oblique angles and less time above the horizon means far less solar energy absorbed at the surface for that hemisphere than in the summer. Very basic stuff. The difference between absorbed solar in the winter vs. summer is much larger than the 4 Wm-2 imbalance from doubled CO2, and so it requires much less time to see a given temperature change deltaT. The hemispheres are no where near equilibrium and they don't need to be to see a large change in temperature." I know. The point is the proportional amount of change that occurs over such a short period of time is way too large to support years or decades to reach equilibrium. -
Eric (skeptic) at 11:56 AM on 23 January 2011Monckton Myth #6: Global Sea Ice
#17 Albatross, Monckton is wrong and I don't think there's anything more to say about it. But michael sweet insisted on using data prior to 1980 and implied that it is flat. #16 nigelj, I posted above because I am "skeptical" that the current record lows are all AGW in origin. Certainly the drop since 1980 has been exacerbated with arctic warming and local feedback especially in recent years. Also, with certainty, earlier declines were natural particularly in max extent (April graph above) as there were less severe winters after the 1880's. The AGW effects show up more in min extent since extent doesn't take into account thickness. #18 dhogaza, I think flat linear is not a good fit at least for maximum ice extent (perhaps better for minimum) because of harsher winters up to the end of the Little Ice Age. The Nordic sea ice extent data in this study http://journals.ametsoc.org/doi/full/10.1175/1520-0442%282001%29014%3C0255%3AAATOSI%3E2.0.CO%3B2 shows a natural decline in maximum extent prior to recent AGW-related declines (post this chart from figure 2).
This is local, not global, as I noted in #5. There is no accurate world wide data prior to the satellite era, just Nordic data and Russian data.
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