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Peter Hogarth at 03:10 AM on 1 June 2010Why Greenland's ice loss matters
Vinny Burgoo at 00:27 AM on 1 June, 2010 Stone 2010 updates the boundary conditions for modeling changes in Greenlands ice sheet with more realistic input data. Specifically bedrock and ice thickness, temperature and precipitation. They use as many recent real observations as possible. In doing so they discover that the modeling run steady state with the new boundary conditions overestimates the current amount of ice by 25% compared with actual observations. Re-tuning the model to obtain more realistic current ice levels and then projecting forwards in time under the 400ppm CO2 scenario, the revised model suggests greatly increased ice loss under all 5 parameter sets compared with the previous unadjusted model, which had “predicted” similar future ice volumes to today at 400ppm. In other words our previous best predictions (or model outputs if you wish to be pedantic) underestimated future ice loss under given conditions, and we now probably have a more realistic model. I’m not sure John has really used this paper out of context, but I’m guessing he’ll comment. If you have other specific cases of misrepresentation, it would be useful to point these out so that amendments can be made if needed. I certainly don’t mind being corrected if it is shown I’ve misunderstood something, and this is probable if I stray from my areas of expertise. I would also hope you adhere to the same critical standards when visiting other sites! -
Riccardo at 02:38 AM on 1 June 2010Why Greenland's ice loss matters
"Although not completely collapsed, the 400p pmv ice-sheets for Figure 12b-e are somewhat reduced in the north of the island, with a reduction in ice volume compared with the modern day ice-sheet volume ranging between 20 to 41%. However, the scenario in Fig. 12f shows almost complete collapse at 400 ppmv with a reduction in ice volume of 81%." this is what the paper says. It's self evident that there's no misinterpretation whatsoever. I find only one (irrelevant) inaccuracy in what John wrote, it's not in 400 hundred years. The paper says that the results shown are after 400 hundred years of model integration, which is not the same thing as 400 years from now. As for the referee's comment, you're largely off target. Stones as well as John here did not make any projection of our future, as the referee advised. Both described what happens in a 400 ppmv world and none of them "predicted" a real world with a constant CO2 concentration at 400 ppmv for centuries. You may not like John's wording but the meaning is straightforward. Although not relevant in this particular case, i agree that research papers are often treated very badly around in the blogsphere. -
Alexandre at 02:38 AM on 1 June 2010Could global brightening be causing global warming?
I did not follow the point. Shouldn't the increase shown in Figure 1 somehow appear in the aerosol lines of Figure 2? Where did I understand it wrong? -
shawnhet at 02:29 AM on 1 June 2010Working out climate sensitivity from satellite measurements
"ONE: Your first point is confused isn’t it? One the one hand you say: ”S&B (and I)are not talking about the long-term feedback response (ie climate sensitivity),…” ...which we can all agree with, since that’s obvious by reading the paper and Spencer and Braswell (S&B) state this explicitly. But then you say: ”However, for a given set of long-term feedbacks S&B predict a less sensitive climate than if short term variations are governed by noise(in S&B's terms).” Respectfully, Chris, it is you who is confused. Let's say we have a forcing that instantly raises the temperature(T1) by 1C. Under S&B, that instant feedback is then acted on by a feedback(SF) that drops the temperature by 0.5C(T2), finally T2 is acted on by a series of long-term feedacks(LF) that multiply it by 3 ie T3=T1*SF*LF. Think about it. If SF is <1, then T3 *must be* less than if SF=1 *where everything else is equal*. Hopefully, now, you can understand where S&B are coming from. " The real world makes sense. In much the same way that a paper can’t at the same time be about climate sensitivity and not be about climate sensitivity, so the climate sensitivity (let’s say the Charney climate sensitivity) can’t be both significant and insignificant at the same time. The earth’s climate as it stands now does respond to enhanced radiative forcing with a surface temperature that rises to a new equilibrium compatible with this forcing. This sensitivity cannot at the same time be very small (~0.5 oC of warming for a radiative forcing equivalent to 2xCO2) and considerably larger (~2-4.5 oC of warming for 2xCO2)." Just FYI, now that you hopefully understand what S&B are saying, there is no contradiction btw assuming a short-term feedback of 0.5C to CO2 forcing, which is **then** multiplied by 2-4.5 by long-term feedback effects. If you combine such a framework with an ocean cycle effect(eg PDO), you have a perfectly sensible explanation of the real world. Cheers, :) -
Alden Griffith at 02:12 AM on 1 June 2010Could global brightening be causing global warming?
Here's my analogy of Monckton's logic: We can think of Monckton's attempt to calculate climate sensitivity from Pinker's 1983-2001 data (http://www.youtube.com/watch?v=og_Bu2zO61g&feature=related) as similar to trying to calculate an automobile's average speed over an entire trip. The problems are that (1) Monckton is estimating the average speed only from the tiny amount of time in which the car actually passes him by (the 1983-2001 period) instead of looking at a longer portion of the trip, and (2) he is forgetting that he too is also in a moving car (not including other opposing radiative effects of clouds and aerosols)! So how much can you say about the average speed of a car from point A to point B by watching it briefly pass you by and forgetting that you are also moving too? Zippity Dooda! Nothing! As Tamino so nicely put it, "if you can't convince them with logic, dazzle them with BS." -
Jim Eager at 02:04 AM on 1 June 2010Could global brightening be causing global warming?
Think CO2e, RSVP. CH4 has gone up by 150%, N2O by 15%. CFCs and other purely engineered chemicals did not even exist. -
Sean A at 01:57 AM on 1 June 2010On temperature and CO2 in the past
Gallopingcamel, are you saying that CO2 doesn't cause warming? You may want to check out a few of the other pieces of the puzzle, for example some recent posts here. Over these timescales, warming increases CO2 which causes more warming: The significance of the CO2 lag Has the greenhouse effect been falsified? -
Vinny Burgoo at 00:27 AM on 1 June 2010Why Greenland's ice loss matters
JC: At 400 ppm, they predict that over the next 400 years, the ice sheet will lose between 20 to 41% of its volume (Stone 2010). Stone 2010 doesn't predict anything. It is an investigation of current deficiencies in ice-mass modelling, not a crystal ball. Referee Comment C194 puts this better than I could: You don’t draw any direct conclusions about the future of the Greenland Ice Sheet from your modelling, and I think this is important not to do that. The conclusion of your work should relate to the model and not to the Greenland Ice Sheet. You have shown that the model is very sensitive to parameters, and hence any conclusions drawn from it about the future of the ice sheet itself should be seen in the light of this sensitivity and the model deficiencies. Otherwise it would be easy for someone to take Fig. 12f, in particular, out of context, to show that Greenland may not exist in a 400ppmv world. You weren't quite that bad. You took Fig. 12e out of context (41% versus 81% loss). Bad enough, though - and, in my experience, entirely typical of how research papers are treated around here. I think this is the fifth misrepresented paper I've found at Skeptical Science. I don't visit very often and I click on very few of your linked references, so five is a worryingly high number, especially as Skeptical Science is widely promoted as a source of balanced and authoritative information. In my experience, it isn't.Response: Vinny, I try to be balanced and accurate in how I represent papers but I've never said I'm infallible. But if I do make errors, I always correct them, I publicly admit my errors as I have done in the past with you and endeavour to not repeat the error. My primary goal is to further an understanding of climate by communicating the full body of evidence - misrepresenting the science is the last thing I want to do.
In this case, I think it's a reach to say Stone 2010 is just about modelling therefore its inappropriate to talk about the model results. While there is still much work to be done on modelling the Greenland ice sheet, does that mean we're not allowed to talk about the model results until they're perfect? In any case, I'm attempting to represent the paper as written, not the comments of that referree's comment. I will point out also that I chose to describe their best case scenario, not the worst case - a bit of IPCC-like conservatism on my part.
But the broader point here is that the Stone 2010 paper is just one result among many. There is also an empirical result (the paleoclimate study on over 6 metres sea level rise in the last interglacial), a semi-empirical result (mapping sea level rise to temperature to predict 75cm to 180cm by 2100. There's an alternative method of modelling glacier dynamics that finds sea level rise of 80 cm to 2 metres by 2100. These papers all use independent methods to arrive at the same conclusion - that Greenland is highly sensitive to sustained warmer temperatures and we can expect it to contribute significant sea level rise over this century and beyond.
So while I appreciate your feedback about Stone 2010 - especially the fact that it has yet to be approved of which I wasn't aware of - can I suggest you don't lose sight of the bigger picture and that you survey the full body of evidence before coming to any conclusions of where Greenland is headed. -
Daved Green at 23:34 PM on 31 May 2010Latest GRACE data on Greenland ice mass
wes george@18 I saw a Documentary on people living in siberia where to bury their dead they melted the permafrost with fire so they could dig a hole , they had to take turns working outside of 15 mins becuase it was so cold , maybe this is what the vikings did ? -
Arkadiusz Semczyszak at 23:23 PM on 31 May 2010On temperature and CO2 in the past
How can we be wrong about the valuation feedback, I again recommend: Interglacials, milankovitch cycles, and carbon dioxide, (Marsh, 2010) -
Arkadiusz Semczyszak at 23:20 PM on 31 May 2010On temperature and CO2 in the past
"In particular, during the warm periods the climate sensitivity is higher than average. In other words, the temperature increase produced by a forcing is higher when the system is in its warm phases." This assertion seems to be contrary to the basics of Eco-cybernetics. If we treat the Earth as a global Ekosfera complex system - with specific boundary conditions, the addition of energy to stabilize it. It is "richer" in energy - "can afford" to run, to strengthen the equivalent feedback - the more stable equilibrium. Yes because of the slowness of action of some feedback, greater stability of the system warm can be seen only over longer periods of time. For example, biocenosis "warm" are more biodiversity, which stabilizes ecosystems (generalizing - The diversity-stability debate, McCann, 2000). In this way, they (the biocenosis - ecosystems), one of the elements stabilizing the climate. "In the previous interglacial (the Eemian), there was a huge overlap between temperature increase and CO2 increase, which makes it near impossible to know the two-way influences. ..." "... professor Jianli Chen of the University of Texas also found that in a previous inter-glacial period called the Eemian, global temperatures were 6C higher than today, with CO2 levels roughly the same." ... the same - why? -
Ken Lambert at 22:58 PM on 31 May 2010Robust warming of the global upper ocean
kdkd #69 Is 16 years of "Robust" global upper ocean warming - which is the subject of this blog; regarded as climate or weather kdkd? If it is climate, then BP and I have illustrated that the large jumps in OHC before 2004 are calibration offsets of the XBT-Argo transition, and most probably illusory. If it is weather 'noise' then the same conclusion applies - not 'robust' but illusory. -
heather stevens at 22:52 PM on 31 May 2010How you can support Skeptical Science
thank you thank you thank you for existing! This site is fantastic. I have enough sense to know that global warming is occurring, but not the technical knowledge to often back up a discussion with a climate change denier. Thanks to this site i'm now armed with a bit more techy detail and will refer my family and friends who are unsure about GW to this site. thank you! heather Assessing the Risk from Sea Level Rise - Climate Change Impact Assessments -
chris at 22:31 PM on 31 May 2010Working out climate sensitivity from satellite measurements
A slightly broader assessment of S&B(2010) “Year zero science” [*]. It’s a little unfortunate to have to consider this, but it’s also sad that the efforts by scientists working in this area are apparently of effectively zero import once a couple of “celebrity crowdpleasers” enter the arena. The studies of Spencer and Braswell (2010) [and Lindzen and Choi (2009)] are two out of dozens of papers that address TOA radiative transfer, and the issue of estimating climate sensitivity from short term radiative response to temperature fluctuations (e.g. see papers cited in John Cook’s top article and here). Outside of proper science forums and quality science blogs (like this one), all of that other work is essentially invisible. Much like Lindzen and Choi (2009), S&B(2010) is already building up a head of blogsphere “steam” and if one looks at the presentations on the subject at a curious climate change politicisation get-together in Chicago a couple of weeks ago, for example, one might think that L&C and S&B is the entire science on this subject! In fact L&C(2009) is the only study that S&B(2010) explicitly refer to as support of one interpretation of their “analysis” [S&B state ” This is similar to the feedbacks diagnosed by Lindzen and Choi [2009] from interannual variability in recently recalibrated Earth Radiation Budget Satellite data…”]. And yet the analysis of Lindzen and Choi (2009) has been shown to be horribly flawed (see top article of this thread). Pretending that the wider science doesn’t exist and that the subject can thus be interpreted in its entirety through a couple of flawed analyses isn’t a good way to understand scientific issues! The real world makes sense. In much the same way that a paper can’t at the same time be about climate sensitivity and not be about climate sensitivity, so the climate sensitivity (let’s say the Charney climate sensitivity) can’t be both significant and insignificant at the same time. The earth’s climate as it stands now does respond to enhanced radiative forcing with a surface temperature that rises to a new equilibrium compatible with this forcing. This sensitivity cannot at the same time be very small (~0.5 oC of warming for a radiative forcing equivalent to 2xCO2) and considerably larger (~2-4.5 oC of warming for 2xCO2). Since (outside of “year zero” “philosophies” of “science”) there is a rather large scientific evidence base that supports the latter climate sensitivity, one needs to provide some strongish evidence if one wants to make headway with scenarios of low climate sensitivity. Likewise if one wishes to pursue very low climate sensitivities, one really needs to explain their fundamental incompatibility with real world observations. After all the rise in atmospheric [CO2] since the mid-late 19th century (290 then to 390 ppm now) is associated with a global temperature rise of 0.8-0.9 oC. We know that the earth’s temperature hasn’t yet risen to the equilibrium temperature compatible with the enhanced greenhouse forcing. We know that atmospheric aerosols have offset some of this warming. And yet within a “year zero” philosophy where everything we know about the real world is thrown out in favour of a cherry-picked selection of data points or wild extrapolation from observations of “linear striations” we are “led” to believe that the huge rise in atmospheric [CO2] has only contributed ~0.15 oC of global warming during the last 150 years. So with all the aerosols we've pumped into the skies the world really should have cooled somewhat during this period, polar, glacier and sea ice should have expanded somewhat, and sea level rise stopped or even started to reverse. Something doesn’t add up…. [*]”Year zero science” could also be termed “clean slate science”, and refers to the “philosophy” whereby a single measurement or analysis is created or selected, and publicised as if it constitutes the essential evidence that bears on a subject while pretending that the wider knowledge base doesn't exist. -
chris at 22:10 PM on 31 May 2010Working out climate sensitivity from satellite measurements
shawnhet at 03:55 AM on 30 May, 2010 You haven’t really addressed my points shawnhet, except (incorrectly) point #5. Perhaps I can make my points clearer. It’s also helpful to address this paper in its wider context since (as we both know) while we’re ostensibly addressing a scientific paper, there’s some interesting “non-science” stuff going with this work and how it’s publicised blogospherically! I’m going to do the latter in a second post – that way if the moderators consider that I’m straying from the science or my post induces a series of follow up non-science posts, it (and they) can be deleted. ONE: Your first point is confused isn’t it? One the one hand you say: ”S&B (and I)are not talking about the long-term feedback response (ie climate sensitivity),…” ...which we can all agree with, since that’s obvious by reading the paper and Spencer and Braswell (S&B) state this explicitly. But then you say: ”However, for a given set of long-term feedbacks S&B predict a less sensitive climate than if short term variations are governed by noise(in S&B's terms).” That odd dichotomy (the paper both isn’t and is about climate sensitivity) is a good example of the confusion that can arise from Spencer’s style of “science by insinuation” (where you say one thing in a scientific paper, and something different on a blog?) I can’t think of another reason how you can simultaneously conclude two incompatible things – one certainly can’t arrive at that conclusion from reading S&B’s paper. TWO: Your first point is correct. S&B state that their “linear striations” don’t have anything necessarily to do with climate sensitivity (the equilibrium surface temperature response to radiative forcing). They find some “linear striations” in an analysis of short term TOA radiation/temperature relationships but don’t quite know what they mean, although they consider that they might have a physical basis. That’s fine. The next step, scientifically-speaking, is to establish what these “striations” are and what they really mean (if anything) in relation to TOA radiative transfer. THREE: I’d say that’s where the science stands on S&B(2010). However it’s perfectly acceptable (scientifically-speaking) to make a presumption about what this might mean, and within that model to assess potential consequences. Lin et al (2010) do this in a couple of papers (cited here). They use S&B’s “linear striations” to parameterize a fast feedback parameter [f(s)] of a radiative transfer model and find that if one uses a model that bears some realism to the real world (i.e. one in which there is a non-zero “inertia” or “memory” in the climate system), that S&B’s “linear striations” are entirely compatible with a real world climate sensitivity consistent with the wealth of independent data (Lin et al find a “best” value for the climate sensitivity of 3.1 oC). Your assertion "You'll note that they had to "add" something to make sense of what Spencer found." isn’t correct. They’aren’t “making sense of what Spencer found”. They are taking an interpretation of S&B’s “linear striations” at face value and addressing how this might affect real world climate sensitivity -
F. Murdoch at 21:37 PM on 31 May 2010Could global brightening be causing global warming?
@RSVP You cannot compare the increase in forcing to the increase in GHG's. After all, at equilibrium the effective forcing would be 0, regardless of the concentration of GHG's. -
PaulK at 20:53 PM on 31 May 2010There's no empirical evidence
Riccardo #98 You wrote: "it's not clear to me what you mean by "the assumptions in your version of the heat balance equation". Which assumptions did "I" make? Did you find something wrong?" I used the term "your version" to be simply descriptive, not pejorative. Strictly we have covered three versions of the heat equation:- Schwartz version:- dH/dt = F * exp(-t/tau) "Your version":- dH/dt = F(t)−λΔT "My version":- dH/dt = -f(t) "Your version" makes the same assumptions that are built into the Schwartz model, and then one additional assumption, which is the curtailment of higher order temperature terms in the exponential expansion (or in the derivative form of S-B apploied to Ts - it comes to the the same thing). I wasn't suggesting that this is "wrong":- each of these versions is founded on its own assumptions. I am claiming that my solution is more general than Schwartz, and hence more general than "your version". Where are we going with this? With real-world data (CO2), over a wide variety of assumptions imposed on "my version", the rise in OLR cannot be reconciled with the IPCC assertions and assumptions. This whole conversation started because, as I stated, the "hand-waving" arguments about CO2 being the primary driver, BUT thermal emissions overwhelm the OLR response don't hold water for the long equilibration times asserted by the IPCC . -
Marcus at 20:49 PM on 31 May 2010Could global brightening be causing global warming?
Consider this though HR. Sunspot numbers have been dropping marginally since 1979-so the amount of radiative energy-in W/Square meter, have been dropping over that time period. So for there to have been even a small rise in radiation at the earth's surface means that there must have been a change in Earth's albedo (reduced aerosols, reduced cloud cover etc etc.) However, as John pointed out-all these things also contribute to the retention of IR radiation as it heads out to the upper atmosphere. So a reduction in clouds & aerosols should-if I understand it correctly-have little effect on the *net* radiation balance-because they mostly offset each-other. The fact that the amount of IR radiation detected in the stratosphere has dropped-in *spite* of the reduction in heat retaining clouds & aerosols gives even greater credence to the idea that it must be increasing GHG emissions which are trapping the heat in the lower atmosphere. Now, I accept that I could have the total wrong end of the stick, but it makes sense to me. What say you, John? -
Marcus at 20:43 PM on 31 May 2010Could global brightening be causing global warming?
Either way, Ed Davies, what RSVP hasn't factored in is that we're *not* just talking about CO2-it represents *all* GHG emissions-& CH4 is a more potent GHG gas, & has risen at a sharper rate than CO2. It could also explain why it leveled off modestly around 1980-the leveling off of methane emissions (but they've started to climb again!) -
Ed Davies at 19:33 PM on 31 May 2010Could global brightening be causing global warming?
"Interesting to see Fig 2 showing that GHG forcing has tripled in the last century when GHG concentration has only increased by a factor of 1.5." Given that the zero point of this graph is, rather obviously, the effective forcings in 1880 don't you think it's an imaginative leap, to put it mildly, to say that the GHG forcing has tripled? -
RSVP at 18:18 PM on 31 May 2010Could global brightening be causing global warming?
Bern I was talking about 250 ppm vs 380 ppm... a factor of 1.5 roughly. The units in Figure 2 depict energy per square meter, not concentration. In terms of the relationship between concentration and energy, concentration is the independent variable, while energy is the dependent variable. Energy normally increases as the square root of a linear change in the independent variable. -
HumanityRules at 18:05 PM on 31 May 2010Could global brightening be causing global warming?
So what does figure 1 tell us? How much of the sun's energy is reaching the surface? This must be of some importance to temperature change? 3.Bern I think it's reduced methane. -
Bern at 17:35 PM on 31 May 2010Could global brightening be causing global warming?
RSVP: the 1900 GHG value in Fig 2 is ~0.2, while the 2000 value is ~2.7 or so. That seems like much more than a tripling to me! It's rather scary to see the GHG forcing was growing exponentially from ~1940 through to the late 1980s or so, where it seems to have tapered off dramatically. Does anyone have any idea why the sudden drop in the rate of increase c.1990? Is it to do with changing patterns of energy use, or something else? -
RSVP at 17:12 PM on 31 May 2010Could global brightening be causing global warming?
Interesting to see Fig 2 showing that GHG forcing has tripled in the last century when GHG concentration has only increased by a factor of 1.5. -
MikeCoombes at 15:31 PM on 31 May 2010Working out climate sensitivity from satellite measurements
Thanks Riccardo for the comment For example, think about downwelling and upwelling and mixing of ocean waters. These movements are not well know and may produce a large unaccounted variability in the short run but tend to average out over longer periods. But we have a hundred years of data to average over. The change in energy from the sun between summer and winter over a hemisphere (N or S) is approximately constant and much larger than most other factors and the consequent temperature change is also large (I would guess about 20C - much more at the poles and less near the equator -) and also roughly constant but with more variability for the reasons you mentioned. I guess I should just try to calculate it. I recall Open Mind had a few blogs on how much various orbital factors affected how much sunlight a hemisphere received. -
villabolo at 15:22 PM on 31 May 2010Could global brightening be causing global warming?
Did not Lord Monckton make an argument once for Global Cooling? You know, the one based on a falsified version of an UAH globally averaged satellite based temperature chart, conveniently cut off at 1998 to show an artefactual drop in temperature? Pray tell, Lord Monckton, which is it? Global Cooling or Global Warming through whatever means? -
johnd at 13:11 PM on 31 May 2010There's no empirical evidence
cherrypicked at 11:46 AM, just to add to my earlier post to help get it into perspective and hopefully not further confuse the matter, temperature drops about 7oC for every 1000m increase in altitude above sea level, that is about 1oC for every 140m increase in height, all other things being equal. -
johnd at 12:40 PM on 31 May 2010There's no empirical evidence
cherrypicked at 11:46 AM, the qualification "or" will apply if you consider how conditions can change given IR radiation is always from the warmer body to the cooler. The relative differences in state between the surface and the atmosphere can be that the surface can be warmer than the atmosphere, OR both the surface and the atmosphere are in equilibrium, OR the surface is cooler than the atmosphere. It is always going to be one OR the other depending on all the variables that combine to produce the climate that exists on this planet. -
cherrypicked at 11:46 AM on 31 May 2010There's no empirical evidence
It can't be a bit of both as you suggest. Warming the atmosphere can only lead to warming the surface if at least some of the warming is directed downwards. Specifically, radiative trapping produces (some) surface radiative forcing. But that is not what Evans said. He said it is one *or* the other. He didn't say it's a bit of both. Also, the sentence makes no sense if we substitute "or" for "and", so it is unlikely a typo. However, "caused by" would fit. -
jfbarsoum at 11:22 AM on 31 May 2010Skeptical Science now a Nokia app
For those of you with other phones (Pre, Android, etc.) you might consider using a good RSS reader app as a stop-gap. There are XML RSS feeds for both the ARguments and the Blog, so if you can read those feeds using a mobile reader, you're golden. -
cherrypicked at 10:58 AM on 31 May 2010There's no empirical evidence
Thank you for the detailed article. I have a question? In the section, co2 traps heat, you quote Evans 2006: The results lead the authors to conclude that "this experimental data should effectively end the argument by skeptics that no experimental evidence exists for the connection between greenhouse gas increases in the atmosphere and global warming." Yet the opening sentence in the link you provide, Evans states: "The earth's climate system is warmed by 35 C due to the emission of downward infrared radiation by greenhouse gases in the atmosphere (surface radiative forcing) or by the absorption of upward infrared radiation (radiative trapping)." It is the use of the conjunction "or" that I am querying. Which is it? Is it surface radiative forcing, or is it radiative trapping? I am *not* suggesting the above statement in some way invalidates Evans' proof, but it does cast doubt on the mechanism responsible for the warming. For completeness, I must point out that this sentence does not appear in the linked article - only the abstract.Response: "Which is it? Is it surface radiative forcing, or is it radiative trapping?"
A little from column A, a little from column B. Greenhouse gases both absorb upward infrared radiation which warms the atmosphere, and also scatter or reemit infrared radiation in all directions, some of which heads back to Earth. -
Bern at 10:56 AM on 31 May 2010Skeptical Science now a Nokia app
doug: Are we talking a phone OS flame war, or a PC OS flame war, or both? Shall we have a flame war about what to have the flame war about? :-P John: very cool, more exposure for this wonderful site. Good to hear an update about the Android app - I await it with bated breath... Hmm, I'm pretty sure that shouldn't be "baited breath"... oh, no, a grammar flame war! :-D -
johnd at 09:41 AM on 31 May 2010Websites to monitor the Arctic Sea Ice
Just to appreciate the difficulties in estimating ice volume, and the need for caution about drawing conclusions from relatively small changes in estimates, the accuracy that applies to measurements made needs to be taken on board. The acknowledged error involved in measuring ice thickness ABOVE the waterline is plus/minus 50mm. Because only about 10% of the ice is above the waterline this error multiplies to plus/minus 500mm which is very significant when first year ice is generally less than 2m thick, meaning less than 200mm freeboard and multi-year ice about 3m thick, meaning 300mm freeboard. All other estimates such as density have their own inbuilt errors, but the error involved in estimating actual ice volume comes down to this relatively large error involved in simply measuring the sea ice freeboard. Even as new technology and techniques improve the accuracy of measuring the ice freeboard, it will be still subject to a factor of 10. Even once that improved accuracy been established, it doesn't change the fact that all measurements obtained in the past will still have those large inbuilt errors which have to be taken into account when comparisons are made with any historical data. -
Berényi Péter at 09:25 AM on 31 May 2010Websites to monitor the Arctic Sea Ice
#22 Riccardo at 06:47 AM on 31 May, 2010 you're just playing war games No, it's the US Navy's job, not mine. And they do play it all the time. It includes verifying the forecast systems operated by smart guys using independent means. I reckon they send out patrols to check model forecast occasionally, ordered to report back their findings. Understanding the ice thickness distribution and its variability is important in both short-term operational forecasts and longer-term climate studies. Model-derived ice thickness fields are useful in obtaining a large-scale, but detailed picture of ice distribution and, more importantly, an understanding of its temporal variability. #25 michael sweet at 08:11 AM on 31 May, 2010 the other is a derived number by a web blogger with unknown error bars You must refer to my attempt. But you are overestimating my role by saying the numbers are derived by me. The algorithm I have run is actually pretty straightforward, the curves come from the PIPS 2.0 24 hour forecast maps. As there are no error bars supplied by PIPS, of course I could not pull out one from thin air. All I can say is errors introduced by the transformation are negligible. Casting doubts does not contribute to understanding. As for sea ice volume, please check the article Has Arctic sea ice returned to normal?, this site.What the science says...
BTW, ice volume graph provided by the Polar Ice Center does not have error bars either.Sea ice extent tells us what about the state of the sea ice at the ocean's surface, not what's happening below. Arctic sea ice has been steadily thinning, even in the last few years while extent increased slightly. Consequently, the total amount of Arctic sea ice in 2008 and 2009 are the lowest on record.
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Riccardo at 08:17 AM on 31 May 2010Climate sensitivity is low
here is a more readable formatting of Lin 2010. ;) -
michael sweet at 08:11 AM on 31 May 2010Websites to monitor the Arctic Sea Ice
I would point out that one estimate of volume is from ice scientists who have estimated their error and the other is a derived number by a web blogger with unknown error bars. You have to choose how you determine what data is worth considering. The difficulty in determining ice volume is one reason why NSIDC uses ice extent. The ice extent is a firmer number than the ice volume. With luck NSIDC will comment on this in their next monthly report. -
Riccardo at 07:53 AM on 31 May 2010Websites to monitor the Arctic Sea Ice
Marcel, as i understand it they both "assimilate" data. Each day PIPS restart the forecast with actual data if their previous forecast was out more than a certain threshold. It's about the same process used for PIOMASS. I think the difference lies in the details. Apart from being the more recent of the two, PIOMAS includes a so called thickness and enthalpy distribution sea ice model which takes into account the rheology of ice and ice ridging. Apparently PIPS does not. I'm not able to go any further on these details, we should ask a specialist. -
Peter Hogarth at 07:36 AM on 31 May 2010Climate sensitivity is low
I am not sure this paper has been mentioned yet. See Lin 2010. Obtains 3.1K for sensitivity, constraining the estimates a little to between 2.8K and 3.7K -
Marcel Bökstedt at 07:14 AM on 31 May 2010Websites to monitor the Arctic Sea Ice
Hmm.. lets just leave what WUWT writes out of this equation. And it's best that BP does not annoy the Navy, they can be nasty if they decide to retaliate. It would still be interesting to explain the differences between the estimates of ice volume. Could it be that the fact that PIPS is essentially a forecast makes it less reliable? (Maybe PIOMAS can use data obtained later than the fact to estimate ice thickness?) -
Riccardo at 06:47 AM on 31 May 2010Websites to monitor the Arctic Sea Ice
Berényi Péter, it's not about what I think but what THEY say, at least in the published papers. Maybe you have access to secret informations, do you? If not, you're just playing war games, not science. I know you can do much better than blindly follow people at WUWT, be skeptical of what they say there too. -
Berényi Péter at 06:44 AM on 31 May 2010Websites to monitor the Arctic Sea Ice
#19 michael sweet at 05:27 AM on 31 May, 2010 The red color shows ice AT LEAST 5 meters thick. Much of that ice was 10 or more meters thick (some was over 30 meters thick) in past years. You cannot integrate it as 5 meters thick.This results in underestimating the ice volume in past years Perhaps it was. But there is not much red in any PIPS map. For example the one for 14 September 1999 does not have any. -
Berényi Péter at 06:30 AM on 31 May 2010Websites to monitor the Arctic Sea Ice
#16 Marcel Bökstedt at 02:12 AM on 31 May, 2010 The difference between the navy data and PIOMAS is striking, even if the graph above of navy data only covers one particular date (is that correct BP?) Yes, that's correct. It is only for 28 May. I could do it for the entire year, but a huge amount of data (about 250 MB) is required to be downloaded and I am not sure the Navy would tolerate it :) Anyway, I've also did it for 14 September, the day Arctic sea ice extent was lowest in 2007.
At that time of the year ice volume inside 70N is about all there is. Interesting to note that mid September ice volume was lowest in 2008, not in 2007. The low in 1999 is also unheard of.
#17 Riccardo at 03:06 AM on 31 May, 2010
PIPS is designed to predict ice concentration essentially near the ice edge and it is tested against this field
I don't think so. For submarines armed with strategic nuclear missiles ice thickness is a deciding factor anywhere in the Arctic. They simply can not do their job if the ice above is too thick.
The Navy also have its own devices to monitor ice conditions including submarines, spy satellites, aircraft and drift buoys. PIPS do have a sophisticated data assimilation facility developed in more than twenty years.
Moderator Response: [Sph] Bad images removed. -
Peter Hogarth at 06:15 AM on 31 May 2010Why Greenland's ice loss matters
FerdiEgb at 06:30 AM on 29 May, 2010 michael sweet at 01:06 AM on 31 May, 2010 easily beat me to a response on similar lines. We see the same Winter variance/Summer "clipping" to just above melt point over the Arctic sea ice. -
michael sweet at 05:27 AM on 31 May 2010Websites to monitor the Arctic Sea Ice
BP: I just looked at the Navy website. The red color shows ice AT LEAST 5 meters thick. Much of that ice was 10 or more meters thick (some was over 30 meters thick)in past years. You cannot integrate it as 5 meters thick. This results in underestimating the ice volume in past years. This alone is probably enough to explain the difference between you and PIOMAS. -
michael sweet at 04:16 AM on 31 May 2010Websites to monitor the Arctic Sea Ice
WUWT has integrated the colors of other peoples ice data unsuccessfully in the past (note here that BP got a lower value than WUWT). While BP has done an interesting analysis, I would not say that the US Navy has said what they think the ice volume is. BP has said what HE thinks the ice volume is based on the Navy graph. This type of analysis has many hidden errors since the Navy graph is not intended for this use. I agree with Riccardo, PIOMAS is intended for this use and will have lower error. PIOMAS undoubtedly has a high resolution map of the Navy graph that they consider in their analysis (unless the Navy gets their data from PIOMAS). -
Riccardo at 03:06 AM on 31 May 2010Websites to monitor the Arctic Sea Ice
Marcel Bökstedt, sometimes happens that critical thinking efficiency drops to zero. A post on WUWT is enough to spread the(ir) "truth". I do not have the answer to your question, obviously, but it should be noticed that PIPS is designed to predict ice concentration essentially near the ice edge and it is tested against this field (see for example here and here). On the contrary, PIOMAS is designed and tested to calculate volume. I'm not that surprised that the two do not match. -
Riccardo at 02:19 AM on 31 May 2010Volcanoes emit more CO2 than humans
JSFarmer, apart of Ian Plimer, (professor of mining geology and director of a few mining companies in Australia) and Mark Durkin (director of the infamous "The Great Global Warming Swindle") I don't think you can find many others disagreeing with your question #1. As for question #2, i've never heard criticism on the numbers. -
Marcel Bökstedt at 02:12 AM on 31 May 2010Websites to monitor the Arctic Sea Ice
The difference between the navy data and PIOMAS is striking, even if the graph above of navy data only covers one particular date (is that correct BP?) According to PIOMAS, there has been a loss of around 9000 km^3 of ice in this period 1999-2010. The navy data shows almost no loss of ice, certainly much less than 9000 km^3. Does anyone have any idea about what is going on here? -
muoncounter at 01:59 AM on 31 May 2010On temperature and CO2 in the past
In #16, Mr. Camel states: "could not find any declaration that the CO2 concentration was driving the temperature changes" However, Riccardo stated this: "... starting about a couple of centuries ago, the system has been suddenly pushed out of its shell and moved to a completely different domain. The slope of the [temp-CO2] curve is hugely different, indeed almost flat, which suggests that the driver of the climate is different from anything seen in half a million years." (Italics added). Perhaps if one drops back a bit and asks "What has driven this hugely different behavior of the temp-CO2 system?" See the following graph:Notes: 1. De-seasoned atmospheric CO2 from 3 widely-spaced sample stations (Mauna Loa, Barrow and Palmer, Antarctica) 2. Composite Law Dome Ice Core (3 sample locations) Ice core air age used as time axis. 3. Carbon emission data Trailing 5 years (residence time?) summed and expressed in gigatons. Looks like a trend to me (pardon the shameless extrapolation into the future). So let's turn the question back on the reader: What explains the relationship between increased burning of fossil fuels and increased atmospheric CO2? And what else do you offer for Riccardo's hugely different driver?
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Riccardo at 01:48 AM on 31 May 2010It's the sun
JSFarmer, look yourself. The picture is from a NASA site.
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