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Riccardo at 01:13 AM on 26 May 2010Greenland rising faster as ice loss accelerates
HumanityRules, yes, they were both going down and now are going up. -
Berényi Péter at 01:00 AM on 26 May 2010Robust warming of the global upper ocean
#41 Riccardo at 22:57 PM on 25 May, 2010 The jump in OHC you claim as an indication of XBT bias is between 2001 and 2003. The two do not match so it is easily discarted as an explanation of the jump Notice change in ARGO coverage please.
Current status:
#43 Ken Lambert at 00:31 AM on 26 May, 2010
BP is simply applying the first law ie. conservation of energy. etc., etc.
Thanks. This is exactly what I was trying to say.
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Riccardo at 00:59 AM on 26 May 2010Greenland rising faster as ice loss accelerates
Ron Crouch, ops, you're right. I myself wrote elsewhere that Iceland sits on the Mid-Atlantic Ridge. Thank you. -
Riccardo at 00:54 AM on 26 May 2010Robust warming of the global upper ocean
Ken Lambert, are you looking here for the answer on the missing heat when professional scientists couldn't yet? The difference between me and you (and BP) is that I do not try to solve the problem by so naively applying conservation of energy. I'm sure that any scientist knows about conservation of energy ... -
Ken Lambert at 00:31 AM on 26 May 2010Robust warming of the global upper ocean
BP#30. CoalGeologist #39, Riccardo #41 BP #30 came up with a jump of 6-8E22 Joules in OHC between 2000 and 2004, and I read Fig 2 as about 7E22 Joules 2001-2003. This translates to a TOA imbalance of about 2.1W/sq.m when model based estimates (Dr Trenberth) calculate 0.9W/sq.m over a similar period. Sharp jumps in short time periods which match the transition to Argo from a much smaller more fragmented XBT system can only be an offset error - an artefact of the transition. A similar jump occurred with the SORCE TIMS monitors which since 2005 read 4.5W/sq.m lower TSI that prior satellites. No-one is trying to splice TIMS to prior satellites or we would have a big drop in incoming solar radiation - a similar offset problem as XBT and Argo. BP is simply applying the first law ie. conservation of energy. If there is an imbalance at TOA then the energy must show up somewhere in the biosphere and the oceans have vastly greater capacity than the land or atmosphere (or ice melt)to store heat energy. The integral of the TOA energy flux imbalance WRT time should show up in the increase in OHC. Where else could it feasibly be absorbed in sufficient quantity? As far as six years of flat OHC data being insufficient to drawing conclusions on warming - then explain where the missing heat is stored in this period when CO2GHG theory requires a continuous and increasing TOA imbalance of about 0.9W/sq.m and rising. -
Ron Crouch at 00:16 AM on 26 May 2010Greenland rising faster as ice loss accelerates
Iceland sits half on the North American plate and half on the Eurasian plate Riccardo. No connection can be made between the volcanic activity in Iceland and the off-loading of ice in Greenland (at least not until any uncertainties can be resolved). The uplift and any lateral movements in the crust at the Greenland margin could have an effect at the plate boundary as I understand it and would be representative of the delayed viscoelastic response as opposed to the current observed uplift which only represents the immediate elastic response (local). If I'm wrong with this analysis could someone more knowledgeable enlighten me. -
HumanityRules at 23:35 PM on 25 May 2010Greenland rising faster as ice loss accelerates
35.Riccardo "Not worth to discuss any further." Okay I'll accept my ignorance on acceleration. So let's get down to basics. Is Fig 1 showing Iceland (and Greenland) subsiding between 1995 and 2000? -
HumanityRules at 23:25 PM on 25 May 2010Robust warming of the global upper ocean
39.CoalGeologist pielke snr in one of his posts suggests that 70% of the increase in OHC seen in this study is accounted for by just 3 years (1999, 2002 and 2003). You can draw a line from 1994 to 2009 and describe a trend the question might be what is the relevance of that. It's naive to suggest just AGW sceptics use the data to tell a particular story. Anybody have any general thoughts on how the very large interannual variability in OCH change impacts on our understanding of real world processes in the ocean? I have in my head that the oceans are a very stable environment. For example this diagram shows much of the volume of the ocean is homogenous, do we have to start thinking that the ocean is much more dynamic in it's transport of energy than we classically thought?
Volumetric temperature-salinity diagram of the world ocean. 75% of the ocean's water have a temperature and salinity within the green region, 99% have a temperature and salinity within the region coloured in cyan. The warm water outside the 75% region is confined to the upper 1000 m of the ocean.
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Riccardo at 23:14 PM on 25 May 2010Polar bear numbers are increasing
Eric, is it your speculation that the cause of the projected population reduction is hunting? In the link you provide there's nothing about it. -
Riccardo at 22:57 PM on 25 May 2010Robust warming of the global upper ocean
Berényi Péter, the heat budget as we know it does not close and no one knows why. I assume you don't know either. Logically, you cannot draw any conclusion from TOA imbalance and OHC, let alone using the OHC to calibrate TOA imbalance. The graph you keep posting shows a steady increase in the number of Argo profiles from 2001 to 2008. The jump in OHC you claim as an indication of XBT bias is between 2001 and 2003. The two do not match so it is easily discarted as an explanation of the jump. All the known sources of bias of the XBT data has been taken into account by Lyman et al. 2010. Definitely there might be more but no one has identified them yet. I assume you didn't either. What's left are just speculations and as such should be taken. -
Eric (skeptic) at 22:20 PM on 25 May 2010Polar bear numbers are increasing
The real current problem for polar bears http://www.bearskin-rugs.com/polar-bear-rugs-c-62.html is that they are worth $8000 dead. -
Eric (skeptic) at 22:14 PM on 25 May 2010Polar bear numbers are increasing
The Norwegian polar bear study group shows polar bear populations declining in 8 areas: http://pbsg.npolar.no/en/status/status-table.html but obfuscates the fact that they are declining because they are hunted. Also their estimates have been challenged by indigenous groups interested in hunting. (e.g. nunavut_government_reduces_baffin_bay_polar_bear_quota/) A more accurate phrasing would be "What the science says: polar bear populations are declining primarily due to overhunting. Their long term survival is at greater risk from declining sea ice."Moderator Response: [RH] Fixing links that are breaking page format. -
Berényi Péter at 20:52 PM on 25 May 2010Robust warming of the global upper ocean
#32 doug_bostrom at 07:26 AM on 25 May, 2010 Do you see a possibility that OHC has in fact increased during the period examined by Lyman et al, and if so do you have a reasonably complete mechanism in mind to explain how it may have completely failed in reliability after ~2003? I don't think it has failed after ~2003. That was the year when global coverage increased tremendously both in extent and density. The quality of instruments also improved a lot, even if some of the ARGO floats used to have problems. Therefore I think OHC data after mass deployment of ARGO floats is more reliable than before. You may consider checking the analysis provided at the Does ocean cooling prove etc. thread.
I don't have anything against the early part of the Lyman reconstruction either. However, the huge rise in their OHC history reconstruction between 2000 and 2004 is not supported by net radiation budget at TOA which was measured in this period indeed. Also, there is very little temporal overlap between XBT and ARGO measurements with small chance for proper intercalibration.
In fact the otherwise indeterminate offset of net radiation budget at TOA can be calibrated against the last 6 years of ARGO OHC data. OHC should be close to the temporal integral of the former signal with little delay because heat storage capacity of climate system is absolutely dominated by the oceans. If it is done, OHC increase during the last 15 years turns out to be much less than claimed by Lymann.
#35 michael sweet at 09:17 AM on 25 May, 2010
It strikes me that for amateurs to dismiss a paper by professionals
Please try to digest first what is said. Follow the links if necessary. Science is not about blind faith in professionals, nor it is about appeal to authority. It is about understanding.
If you find answers you do understand to questions I have raised here in papers published by professionals in the peer reviewed literature, you are most welcome should you decide to share it. The same applies to the case you happen to find valid answers on your own.
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CoalGeologist at 19:22 PM on 25 May 2010Robust warming of the global upper ocean
Humanity Rules @36, Although I gather you were aiming at sarcasm, I believe you're approaching a reasonable explanation of what John was getting at in using the term "robust". Bearing in mind that climate is defined on the basis of long-term trends--variously defined at 20 or 30 years--shorter term oscillations of 4 to 6 years such as you describe, are not meaningful in quantifying the effects of climate change. Thus, although your description, "4 years of little to no warming, 6 years of intense warming and finally 6 years of no warming" might evoke some guffaws from those who question the validity of AGW, your usage of the term "warming" is different from its intended meaning with respect to climate change. Assuming the data have been measured and processed reasonably, the observed increase in temperature provides robust evidence of a warming climate on a multi-decadal scale. Given the uncertainty in the data, however, and the shortness of the measurement interval, we're still not sure of the longer term trend. I seem to detect an "inconsistency" in how temperature data are treated by AGW skeptics. On the one hand, some argue that the data are biased toward warming or are otherwise unreliable, er.... that is, until we hit a few years of (apparently!) declining temperature, at which point the previously worthless data suddenly provide clear evidence that warming has stopped! What's up with that?! The more valid question here, is whether the "offset" in the temperature data noted by Berényi Péter@ #6 is a relict of the measurement methodology. The difference in temperature from 2002 to 2004 appears to be statistically significant, yet we can't define meaningful trends on the basis of just 2 or 3 data points. Unfortunately, I'll have to defer to qualified experts to sort this out. In the meantime, given the importance of the answer, I will agree that it is indeed a travesty that we can't do better at present. -
James Wight at 18:52 PM on 25 May 2010It's not happening
Have you thought of adding to this list the decline in lizard populations, and the warming of Lake Tanganyika?Response: I hadn't but I have now :-) Thanks for the suggestion. I've also added both to the positives and negatives of global warming. -
Riccardo at 18:25 PM on 25 May 2010Greenland rising faster as ice loss accelerates
wanyden, it has been proposed (here the original paper, paywalled) that the lowering of the ice load may trigger more intense volcanism. The effect would be local, i.e. melting of glaciers in Iceland would trigger more volcanic activity there. Melting in Greenland has probably nothing to do with volcanic activity in Iceland, they are also on different tectonic plates. -
fydijkstra at 18:11 PM on 25 May 2010Greenland rising faster as ice loss accelerates
It’s all true, what you say in this post about accelerating ice loss from Greenland, but it’s not the whole truth. Let’s put the things in the right perspective. 1. The Greenland ice cap has a total mass of 2.85 million GT. The estimates of the present annual ice loss converge to 250-300 GT, let’s say 285 GT to get round figures. The annual ice loss is 0.01% of the ice cap. With the present melting rate it would require 10,000 years for the ice cap to melt completely. 2. The uncertainties in the estimates of the annual ice loss are high: the error bars are 20 to 50% of the values. The uncertainty in the slope of the line is much higher. You do not give an error bar, but I suspect that the error bar could cover any value between 0 and 100%. Any extrapolation of such data is highly speculative. 3. “If the acceleration continues, Greenland could soon become the largest contributor to global sea level rise.” Melting of the whole ice cap would cause a sea level rise of 7.2 meters. The present annual ice loss is good for 0.01% of that figure, i.e. 0.72 mm, which is one quarter of the sea level rise of 2.8 mm/year. If other factors remain constant, a tripling of the melting rate would make it the largest contributor. With the present estimate of the acceleration we have to wait 28 years. If other factors also increase, we have to wait much longer. It is a matter of taste whether you want to call this ‘soon’. 4. There is no reason to suppose, that the acceleration of the ice loss will continue for a long time. The process can be reversed as well. The temperature on Greenland has always fluctuated strongly. In 1930, 1947 and 1960 it was higher than today. Between 1920 and 1930 the temperature at the Greenland coast increased 2 degrees. In the Middle Ages it was much higher than today, as we all know form historical sources. Greenland’s temperature has only little to do with the average global temperature. Changes in persistent wind patters have much more influence. See for instance: X. Fettweis, E. Hanna, H. Gasllée, P. Huybrechts, M. Erpicum – Estimation of the Greenland ice sheet surface mass balance for the 20th and 21st centuries - The Cryosphere 2(2008), 117-129. 5. Melting of the Greenland ice sheet has little influence on the sea level in Britain and the Netherlands because Greenland is very near on a global scale. The gravitational effect of the ice cap causes a higher sea level in the North Atlantic Ocean and surrounding seas. The disappearance of this effect on melting of the ice cap compensates the sea level rise.Response: "There is no reason to suppose, that the acceleration of the ice loss will continue for a long time"
The evidence that Greenland is highly sensitive to sustained warmer temperatures comes from the past. In the last interglacial, around 125,000 years ago, sea levels were at least 6 metres higher than current with global temperatures around 1 to 2 degrees warmer. Ice melt from Greenland and Antarctica were the main contributors to this sea level rise.
The past can tell us a lot about our future. -
Riccardo at 18:05 PM on 25 May 2010Greenland rising faster as ice loss accelerates
HumanityRules, "When the thing reaches the top and stops it has no velocity or acceleration." Absolutely no. This very very basic kinematics. Not worth to discuss any further. -
HumanityRules at 17:53 PM on 25 May 2010Greenland rising faster as ice loss accelerates
32.wanyden I believe your theory has been suggested. -
HumanityRules at 17:52 PM on 25 May 2010Greenland rising faster as ice loss accelerates
Thanks again John but I'm still blocked. 31 Riccardo When the thing reaches the top and stops it has no velocity or acceleration. So if acceleration is constant in your example it's because there is no acceleration through the whole process. But that seems wrong. I guess we're I'm going with this is that the title of the paper worries me. Instead of "Accelerating uplift in the North Atlantic region as an indicator of ice loss" More accurately it should be something like. "Change in displacement in the North Atlantic region as an indicator of ice loss and gain." Because there appears to be periods when mass is rising and when mass is falling. It's fair to say the last decade has seen mass falling at an accelerated rate but this was preceded by mass gains in the 1990's. Kely is an example of this in post 4 as well. Or is this me still mis-understanding acceleration. -
wanyden at 17:39 PM on 25 May 2010Greenland rising faster as ice loss accelerates
So, here's a question I was asked a few weeks ago in my capacity as volunteer guide at the Monterey Bay Aquarium: Could the eruption of the [Eyjafjallajökull] volcano in Iceland have been caused by some aspect of global warming? At the time I answered that it was highly unlikely. Could I have been wrong? Might the uplift of Greenland bedrock have caused a tectonic movement that stimulated the volcanic action under Iceland leading to the eruption? -
Riccardo at 17:13 PM on 25 May 2010Greenland rising faster as ice loss accelerates
HumanityRules, when you throw something straight up it slows down, stops and falls back. Acceleration is constant throuhout the path, velocity varies. And yes, it's a seasonal cycle. -
Riccardo at 17:09 PM on 25 May 2010Robust warming of the global upper ocean
HumanityRules, the main effort was on the bias corrections of the XBT data, considered the weak part of the OHC dataset. Then the full dataset allow the author (not me!) to come to more robust conclusions. Your claim that there has not been any attempt to close the energy budget is astonishing. Many scientists has worked on that for years and are still working. Anyways, keep in mind that the they are missing the closure for a few tenth of W/m^2; unacceptably large, ok, but still they're not completely missing the goal. Finally, the closure of the energy budget does not prove or disprove anything about climate change and AGW theory. It's just about the ability to measure the energy of our planet, about the understanding of how our climate works. -
HumanityRules at 17:08 PM on 25 May 2010Greenland rising faster as ice loss accelerates
Thanks John but I still need the whole truth to emerge for me. It's being blocked by yet more dumbness. "Iceland is subsiding. But this subsiding is slowing down, stopping, then rising. The acceleration rate is fairly constant through this whole period." I guess now I don't get how the acceleration can be constant through this whole period. If it's subsiding, stops, then rises it's essentially changed direction how can acceleration continue through that reversal? Surely the subsiding decelerated stopped and then rising started. This rising has accelerated since 2000. I can accept that much.Response: Just imagine if your car is slowly rolling down a hill. You start pushing it back upwards. The car starts to slow it's downhill descent. Let's say with your pushing, the car is slowing down at a rate of 1 metre per second per second. Eg - every second, the car's speed slows down by 1 metre per second.
The car stops rolling downhill. If you keep pushing, the car will then start to roll up the hill. If you push at the same rate, the car will then accelerate at a rate of 1 metre per second per second. So the car's "acceleration" is constant over the whole time - it's always going in the same direction (uphill).
Not sure if I'm explaining this right - someone else want to have a go? -
Riccardo at 16:46 PM on 25 May 2010Arctic sea ice has recovered
Eric, I didn't mean that PIOMAS is a perfect model, just that even a hypothetical perfect model would fail the forecast if the input data are not good enough. -
HumanityRules at 16:38 PM on 25 May 2010Greenland rising faster as ice loss accelerates
Is that a seasonal signal in Fig 1 or an artifact of the measurement method? Sorry for the dumbness but I can't get my head around what it's showing in Fig 1. "the amount of acceleration". Does that mean for example that for Iceland the rate of acceleration slowed from 1995 to 2000 and then picked up again?Response: I don't recall off the top of my head if the paper says either way but I do believe it is a seasonal cycle. Makes sense - ice melts in summer, less ice, base uplifts.
Re Figure 1, I confess I did have to stare at it for a while before the truth emerged. Take Iceland for example. What the graph shows is essentially the height of the base (or more technically precise, the anomaly of the height). At the beginning of the measurement period, Iceland is subsiding. But this subsiding is slowing down, stopping, then rising. The acceleration rate is fairly constant through this whole period. -
scaddenp at 12:38 PM on 25 May 2010It's cooling
michaelkourlas - why do you think John spends time on discussing the ocean heat above? Pay particular attention to John's first 2 sentences above. -
HumanityRules at 12:18 PM on 25 May 2010Robust warming of the global upper ocean
33.Riccardo It is a good job that Lyman do in pulling together the available data on OHC. The problem for me comes in the robustness of conclusions. The only tools designed to do the job this paper describes are teh Argo floats. These have yet to find a warming signal in the 5 or so years they've been operating. It seems extra-ordinary based on this fact alone that you would come to the conclusion this paper has. Place this data in the real world and as Trenberth says it still doesn't account for the missing heat. Having said that speculation on the missing heat seems even more wild given there doesn't seem to be any attempt to link the missing heat with any real world physical process that would allow the heat to go missing. It seems a really strange time to make such a forthright statement on this aspect of climate change when the data would not seem to fully support the climate change hypothesis. -
Eric (skeptic) at 12:00 PM on 25 May 2010Volcanoes emit more CO2 than humans
JMurphy, I posted a response earlier, but it may have been deleted or I might have screwed up. I didn't say much more than I disagree mainly because the EU cuts (and naturally the volcano) are inconsequential for climate. But that argument probably belongs on a different thread. -
Eric (skeptic) at 11:45 AM on 25 May 2010Arctic sea ice has recovered
Riccardo, keep in mind the "perfectly able" is qualified by the need for parameterizations related to the forcings. As a simple example, the extent and temperatures of ocean currents under the ice. Those calculations are very similar to a prediction except used for the present time. I can't interpret the graph you show without the description of how it was derived, but from the looks of it, the model is verifying about 5 years of actual volume measurements. I understand how the GCM adds both predictive value and uncertainties, but those are certainly not the only source of uncertainties in the model (except in the hypothetical case of a perfect model). -
HumanityRules at 11:45 AM on 25 May 2010Robust warming of the global upper ocean
1.tobyjoyce I guess robust means 16years. And those 16 years can be separated into three phases. 4 years of little to no warming, 6 years of intense warming and finally 6 years of no warming. That would be what robust means. But this sort of detail gets in the way of the message which is the oceans are warming. -
Eric (skeptic) at 11:38 AM on 25 May 2010Arctic sea ice has recovered
doug, I think the latter part of the curve has been verified, which I believe is about 5 years worth of data. Prior to that the verification relies on measurements of the same factors to calculate volume that were used in the volume and extent prediction (made in 2007 for 2008), namely forcings like weather and ENSO. Obviously those are well known for the past rather than predicted for 2008, but the ensemble used a variety of them to attempt to predict 2008 which all resulted in an underestimated ice extent. Not useless and the trend is correct, but I don't know how accurate the long term slope is. -
Doug Bostrom at 11:35 AM on 25 May 2010It's cooling
Michael, I think one of the things you're missing is taking a moment to read John's post, or if you have and believe you've found something wrong there, perhaps you could mention it? -
Pat Moffitt at 11:29 AM on 25 May 2010Unprecedented Warming in Lake Tanganyika and its impact on humanity
BSI is being used as a proxy for productivity. Generally using BSI requires that diatoms comprise the majority of the primary producers. A recent paper by Stenuite et al in the J. of Plankton Research "Photosynthetic picoplankton in Lake Tanganyika: biomass distribution patterns with depth, season and basin" http://plankt.oxfordjournals.org/cgi/content/short/31/12/1531 found that picocyanobacteria ranged from 44 to 99% of total phytoplankton biomass. On the limnology of Lake Tanganyika- Victor Theodorus Langenberg thesis-rejects Verburgs (used by Tierney as suport for BSI proxy) contention that changes in phytoplankton biomass (biovolume), in dissolved silica and in transparency support the idea of declining productivity. -
michaelkourlas at 11:13 AM on 25 May 2010It's cooling
I'm sorry but I think I'm missing something. Both surface and atmospheric measurements show cooling, or, at least, minimal warming since 2002. How can the planet be accumulating heat when over the course of 8 years global temperature records show it has not really warmed at all? -
Jeff Freymueller at 09:51 AM on 25 May 2010Greenland rising faster as ice loss accelerates
#29 Joe Blog, I don't know much about the details of pre-20th century glacial history of Greenland, but I think you are correct that there were general glacial advances over the last millenium. When the glaciers and ice sheet gain mass, the land will subside just as it is uplifting now as the ice is melting. In fact, you can see prominent annual cycles of uplift and subsidence in many of the time series shown in the main post, and most of that variation is due to the load change from the accumulation of snow and ice in the winter and its melt in spring through fall. See Grapenthin et al. (2006) for the case of Iceland. -
michael sweet at 09:17 AM on 25 May 2010Robust warming of the global upper ocean
It strikes me that for amateurs to dismiss a paper by professionals published in Nature as 'Just nonsense" and "not measured in any reasonable sense" based on eyeballing their graphs is just nonsense and not reasonable. Please provide citations of reviewed papers that show the problems you claim are obvious. -
chris at 08:56 AM on 25 May 2010Southern sea ice is increasing
GFW at 08:16 AM on 25 May, 2010 GFW, this isn't exactly what you're asking for. However many early models of the 80's/90's showed greatly delayed Antarctic warming compared to rapid Arctic warming. This is due (a) to the very large Southern hemisphere oceans and (b) different S and N polar ocean circulation which gives more efficient mixing of surface and deeper waters in the deep S hemisphere, transferring heat from the surface. So, quoting from a recent review of ocean circulation modelling in which the mechanisms for hemispheric warming asymmetry are described illustrates that highly delayed Antarctic Circumpolar ocean warming has been predicted since the early 1980’s. Here’s a bit of a summary from (direct excerpts are in blockquotes): S. Manabe and R. J. Stouffer (2007) Role of Ocean in Global Warming J. Meterolog. Soc. Jpn. 85B 385-403. General point about ocean modulation of surface warming:“In response to the increase in greenhouse gas in the atmosphere, the positive temperature anomaly initially appears in the well-mixed surface layer of the ocean called the “mixed layer”. Gradually, the anomaly spreads from the mixed-layer to the deeper layers of the ocean, thereby increasing the effective heat capacity of the oceans. The increase of effective heat capacity, in turn, results in the reduction of the rate of increase in surface temperature, reducing and delaying the warming as shown by Hoffert et al (1980) and Hansen et al. (1984).”
Discussing the early models of Schneider and Thompson (1981) to evaluate the delay in the response of the sea surface temperature to gradual increase in CO2, Manabe and Stouffer say:"Their study shows that the time-dependent response of zonal mean surface temperature differs significantly from its equilibrium response particularly in those latitude belts, where the fraction of ocean-covered area is relatively large. Based upon the study, they conjectured that the response in the Southern Hemisphere should be delayed as compared to that in the Northern Hemisphere because of the inter-hemisphere difference in the fraction of the area covered by the oceans.”
In a later model Bryan et al (1988) made the same sort of analysis, investigating the role of the oceans in modulating the response of surface warming to enhanced greenhouse gases."They found that the increase in surface temperature is very small in the Circumpolar Ocean of the Southern Hemisphere in contrast to high latitudes of the Northern Hemisphere where the increase is relatively large.”
It’s not just the oceans per so of course. It’s also ocean and air currents, and particularly the mechanisms governing the efficiency of surface heat transfer into the deeper oceans. If this is efficient, the deep oceans will absorb heat and there might be little measured surface warming, at least for a while. So (speaking of Bryan et al (1988)) again:"However, the detailed analysis of the numerical experiment reveals that the absence of substantial surface warming in the Circumpolar Ocean is attributable not only to the large fraction of the area covered by the oceans but also to the deep penetration of positive temperature anomaly into the oceans.”
Later models predict the same hemispherical asymmetry that is seen in the real world. e.g. discussing the simulations of Manabe et al (1992):“Figure 3 also reveals that there is a large asymmetry in surface warming between the two hemispheres. In the Northern Hemisphere, the surface warming increases with increasing latitude, and is particularly large in the Arctic Ocean. This is in sharp contrast to the Southern Hemisphere, where warming is relatively large in low latitudes and decreases with increasing latitudes. It becomes small in the Circumpolar Ocean of the Southern Hemisphere, particularly in the immediate vicinity of Antarctic Continent.”
Why is this, one might ask?! Here’s what Manabe and Stouffer say:"One can ask: why the polar amplification of warming does not occur in the Southern Hemisphere, despite the existence of extensive sea ice which has a positive albedo feedback? As discussed in the following section, the absence of significant warming in the Circumpolar Ocean of the Southern hemisphere is attributable mainly to the large thermal inertia of the ocean, which results from very effective mixing between the surface layer and the deeper layers of ocean in this region. This is in sharp contrast to the Arctic Ocean, where very stable layer of halocline prevents mixing between the surface layer and the deeper layer of the ocean" ......."In view of the absence of significant surface warming, it is not surprising that the area coverage of sea ice hardly changes in the Circumpolar Ocean despite the CO2-doubling.”
n.b. remember this is a prediction from a model involving the response to [CO2] doubling; we’re nowhere near CO2 doubling yet. However these early models predicted what we're seeing in the real world today. -
billkerr at 08:53 AM on 25 May 2010Robust warming of the global upper ocean
roger pielke snr's article, My Perspective On The Nature Commentary By Kevin Trenberth is relevant to this discussion -
GFW at 08:16 AM on 25 May 2010Southern sea ice is increasing
John, I swear it was somewhere on this site, but I can't find it ... There's a paper from the early 1990s where the GCM the authors were using predicted increasing antarctic ice, which puzzled them, and they found it was the increased precipitation (lowering surface salinity) that was doing it (in the model). It's really quite a coup to have predicted the increase and to have attributed it to one of the mechanisms now believed to underlie the observed increase. If you know what paper I'm talking about, it deserves a shout-out from this page. Thanks!Response: I think you must've seen that paper somewhere else - the only papers I include on Antarctic sea ice analyse the trends after the event. But if you do track down this paper, please do post the URL here, thanks! -
J Bowers at 08:16 AM on 25 May 2010Greenland rising faster as ice loss accelerates
@ 26 The Ville What's gained in the UK at one end is lost at the other. Greenland is gaining at both ends. Last I heard, Britiain's isostatic rebound wasn't accelerating either, nor have each ends' rebounds decided to go in the opposite direction in the past few years. Different situation. -
Riccardo at 08:07 AM on 25 May 2010Arctic sea ice has recovered
Eric, suppose that the ice volume model is perfectly able to calculate the true ice volume when you plug in past and current measured data. You then try to predict next season and plug in a GCM projection of the relevant physical quantities, i.e. weather evolution. It may well turn out to be wrong. What do you conclude? Sure the input data were wrong. Hence, a wrong forecast does not invalidate the ice volume calculations. So it is essential to separate the problem in two parts. The first is validation of the model calculation of ice volume. It has been done and it is shown here. And this is also the topic in this post. If the authors are confident with the results, they may want to try a forecast, but now they're adding the uncertainties of the GCM and chances are they dominate for the reasons you said. I can't tell if something went wrong or if it was just the expected uncertainty, one really need to be an expert on arctic ice behaviour. You might want to ask directly to the authors. -
Joe Blog at 08:00 AM on 25 May 2010Greenland rising faster as ice loss accelerates
I have a question that hopefully some of the informed commentators here can enlighten me on. Ok so its generally agreed by both sides o the AGW debate (and ice cores show) that Greenland was warmer some 1kybp. So during that time, is it likely that rebound would have been similar to today? And during the cooling of that land mass that ensued in later years, did it subside? or has rebound generally been positive since the last glacial maximum? -
Doug Bostrom at 07:45 AM on 25 May 2010Arctic sea ice has recovered
Not to barge in, Eric, but how -much- of figure 2 is inaccurate, in your estimation? How wrong is it? Is it useless? Is the trend reflected in the figure entirely absent? -
Riccardo at 07:38 AM on 25 May 2010Robust warming of the global upper ocean
Berényi Péter, i'm not going to follow you along this path. You are arbitrarly forcing the dichotomy yes/no, right/wrong, to make your preconceived point. The reality of good research is different by definition. As pointed out in my previous comment we all agree and know that there are problems and science is finding problems and trying to solve them as best as we can. This is what Lyman et al did and it's a good job. You've not been able to find any valid reason to dismiss the paper and it is only your a-scientific dichotomy that allos you to say that it's all wrong. In this way you're putting yourself outside the realm of science. And this is why I won't follow you. -
mspelto at 07:29 AM on 25 May 2010Greenland rising faster as ice loss accelerates
GFW it is an interesting question. However, we do not have an undermine issue in Greenland, there is not a danger of the major glaciers or the ice sheet developing into ice shelves. Yes some the very end of marine terminating outlet glaciers in the south are afloat and larger sections of some of the marine terminating northern glacier are, see Petermann Glacier are afloat. MS is right this is not a meaningful change. -
Eric (skeptic) at 07:27 AM on 25 May 2010Arctic sea ice has recovered
Riccardo, thanks again for keeping track and responding. You are right that the figure is based on a model of the past which is different from a prediction of the future. But it is the same model. Many of the same factors are used both to model the past and predict the future, ocean and air temperatures being major examples. There are other factors can't be predicted or are very difficult to predict due to chaotic effects, like weather patterns and El Nino. As you point out, they use an ensemble for that purpose using the historical factors for the previous 7 seasons. However all of the ensemble predictions were less than the 2008 actual. So either 2008 was a very unusual year weatherwise or the model fails to properly integrate the recorded weather into the calculated ice volume. I'm inclined to believe the latter which is why I don't believe fig 2 above is accurate either. -
Doug Bostrom at 07:26 AM on 25 May 2010Robust warming of the global upper ocean
Berényi I just read your post more carefully and I should amend my question. Do you see a possibility that OHC has in fact increased during the period examined by Lyman et al, and if so do you have a reasonably complete mechanism in mind to explain how it may have completely failed in reliability after ~2003? I think you need to supply more detail to describe how the failure you see has occurred. -
Doug Bostrom at 07:17 AM on 25 May 2010Robust warming of the global upper ocean
Berényi, can I take your analysis as a "yes" on my question of whether anybody believes the current OHC measurement capability is entirely unable to detect a trend in temperature? Assuming that to be the case, is it capable of any useful measurements at all? Can you place any boundaries on its accuracy, and if so can you show how? -
michael sweet at 07:10 AM on 25 May 2010Greenland rising faster as ice loss accelerates
GFW, The glaciers can be more than 1,000 meters thick at the melt front. If the uplift is 1 cm/year, it will take forever to get a meaningful change. It was an interesting question.
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