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andylee at 03:02 AM on 20 May 2012David Evans: All at Sea about Ocean Warming and Sea Level Rise
According to Jim Hansen the energy imbalance is equivalent to 400,000 Hiroshima bombs per day - this is nearly 5 bombs per second, not 2 as stated above. -
ralbin at 02:55 AM on 20 May 2012Who Are the Most Prominent Advocates of Global Warming?
This is, of course, excellent. But this is the same Mrs. Thatcher who stated "there is no such thing as society" and whose strident advocacy of neoliberalism played a significant role in undermining the legitimacy of dealing with environmental problems. This makes her recognition of global warming more salient but it shouldn't obscure her significant culpability for the difficulties experienced in developing sensible policy responses to global warming. -
Alexandre at 02:24 AM on 20 May 2012Who Are the Most Prominent Advocates of Global Warming?
Why don't we have politicians like that nowadays? Maybe the deniers were indeed successful in manufacturing the controversy in the meantime. It became a touchy subject now. -
Daniel Bailey at 01:26 AM on 20 May 2012CO2 lags temperature
"And with all of that said, the next orbital configuration to really get us into a true glacial state isn't supposed to be for another 10,000 to 20,000 years"
Earlier, Tyrrell et al 2007 examined this, concluding that we have already skipped the next glacial epoch. Furthermore, Tyrrell concludes that if we continue our present fossil fuel consumption, we will skip the next 5 glacial epochs. With that said, per Tzedakis et al 2012, “glacial inception would require CO2 concentrations below preindustrial levels of 280 ppmv” (for reference, we are at about 396 right now…and climbing). With the millennial atmospheric lifetime of CO2, no glacial epochs will be occurring the next million years… -
otter17 at 01:09 AM on 20 May 2012Hockey stick is broken
It seems that the link to the reconstruction data is broken (third link in the 'Further Reading' section). Current Link (broken): http://www.ncdc.noaa.gov/paleo/pubs/ Suggested Link: http://www.ncdc.noaa.gov/paleo/data.html -
Bob Lacatena at 01:02 AM on 20 May 2012CO2 lags temperature
Dougal, Just to state it a little more directly (as to why the rise is fast, but the decline is slow)... it's a lot easier to melt the ice sheets and thereby increase CO2 and heat the planet, than it is to reduce the CO2, and thereby cool the planet and create new ice sheets. The two processes are not exact, diametric opposites. Hence the difference. -
dorlomin at 01:01 AM on 20 May 2012Who Are the Most Prominent Advocates of Global Warming?
Angela Merkel. Phd quantum chemistry. Conservative femail politician, pro action on global warming. -
Bob Lacatena at 00:57 AM on 20 May 2012CO2 lags temperature
Dougal, On the graphs, "temperature change" means increase or decrease from a chosen baseline (our current climate). The data is from this paper by Petit (2000) and is done by proxy (O18 isotope levels), and as such is relative to current O18 isotope levels (which are indicative of current temperatures). This is why it is presented as "difference from today" rather than an absolute value, because what is being used to present the data is a difference, not an absolute, in something else. [It's rather like measuring the change in the tide. You can see how much the water level has risen by looking at a marker on a pole, without necessarily knowing how deep the water is beneath the pole. You can confidently say the water has risen X inches -- the change -- but it doesn't really make sense to bother to try to make that into an absolute depth.] -
Bob Lacatena at 00:48 AM on 20 May 2012CO2 lags temperature
Dougal, To translate what I just explained... there are basically tipping points. Once the ice sheets start to grow, that continues and the planet falls into a glacial state. It will remain there until a variety of orbital factors combine to toggle the system in the other direction. The rise is then fast once the change has been kick-started. I'm unsure exactly why the opposite is so gradual, except that it is really sort of the natural state of the planet (to be partially ice-covered, that is), but it takes a very, very long time to draw down CO2 once it has been increased. That CO2 blanket keeps the planet warm and the ice sheets from expanding even though otherwise the orbital configuration "wants" the planet to be in a glacial state. And with all of that said, the next orbital configuration to really get us into a true glacial state isn't supposed to be for another 10,000 to 20,000 years (it's not that easy to compute), so that at least is not really worth discussing. -
Bob Lacatena at 00:43 AM on 20 May 2012CO2 lags temperature
Dougal,I would expect the gross heat effect from the Milankovitch cycles to be a maximum when closest and least when furthest (with smaller variations caused by tilt and wobble)...
I think this points to a misunderstanding of what happens due to orbital variations. The earth does not get warmer or colder due to distance from the sun. It actually doesn't get very much warmer or colder at all due to the variations in orbit. All that changes is the length and intensity of the seasons in each hemisphere. Because the northern hemisphere is mostly land, particularly in that sensitive area around the poles (Siberia, Canada), while the southern hemisphere is mostly water, then the length and duration of the northern hemisphere summer becomes key. If summer is too short and cool, then ice sheets can grow and expand in the NH. These reflect a lot more of the incoming sunlight than either open water, tundra or vegetation covered land. That actually changes the temperature of the planet and cools it off. Conversely, when the axial tilt and other factors conspire to lengthen/strengthen the NH summer, the ice sheets will have longer to melt and less time to grow back in winter. The earth will absorb more sunlight/energy (instead of reflecting it back into space). This will warm the earth, and add to the retreat of the ice sheets. Then CO2 adds its punch on top of that. -
Bob Lacatena at 00:38 AM on 20 May 2012CO2 lags temperature
Dougal, I'll answer your post in parts, because it is so long. I'm not entirely sure I understand all of what you're saying, because you seem to include some misunderstandings in there. First, the simple and most important point:What I am missing is why the extra man-made forcing is such a critical factor for earth's climate.
Because the amount of carbon available to the system has been well constrained in the last 800,000 years to pretty much stay below 300 ppm, even at peak. There simply wasn't enough carbon to go around for feedbacks to keep adding CO2 beyond that. It took man, digging up 337 Gt of carbon (and counting) that had previously been sequestered underground in fossil form to provide a source of carbon that would allow levels to rise above 300 ppm. A large portion of the temperature rise from glacial to interglacial is due to CO2 feedbacks due to the 100 ppm increase. So why wouldn't a further 100 ppm, 200 ppm or more greatly influence temperatures? -
John Hartz at 00:35 AM on 20 May 2012David Evans: All at Sea about Ocean Warming and Sea Level Rise
@Rob Painting: The section header, "Not Evan wrong" confuses me. Is it correct? -
Kevin Hood at 00:34 AM on 20 May 2012David Evans: All at Sea about Ocean Warming and Sea Level Rise
Would the infusion of frigid glacier meltwater from Antarctica and Greenland be sufficient to counter the ocean's thermal expansion to a measurable degree? -
Dougal at 23:47 PM on 19 May 2012CO2 lags temperature
Hi, just joined the site trying to find clarification on some areas of climate change. I came here on recommendation from another forum to get info on why the CO2 lagging temperature wasn't counter to the claims regarding danger of increased CO2. I have ploughed halfway through these comments, with a couple of sidetracks along the way for linked articles. Although several of my initial questions have been answered in the article or in responses to other posters, there is a new one that either haven't been or I missed/misunderstood. If it has already been answered or are answered in the remaining comments please bear with me. I get the Milankovitch cycles and how it changes the gross heat entering the earth, and am happy with CO2 radiation absorption and vapour pressure causing oceans to release CO2 as they heat up which then absorbs more heat, which causes positive (but not runaway) feedback. I also get the difference between CO2 lagging temperature because it is a feedback mechanism, and the current man-made CO2 increase which is acting as a forcing mechanism. What I am missing is why the extra man-made forcing is such a critical factor for earth's climate. I don't mean for the effect on large numbers of species that may/will go extinct because they can not change or migrate fast enough, and I am not considering the serious issues associated with innundation of low lying areas cause by 1-2m sea level rises. But it seems from the cycles over the last 500k years, that there is some sort of feedback system that always strongly brings the temperature back down despite maximum CO2 levels for some time after the temperature starts falling. I would expect the gross heat effect from the Milankovitch cycles to be a maximum when closest and least when furthest (with smaller variations caused by tilt and wobble), so would expect the temperature, even with feedback mechanisms when both heating and cooling, to be cyclical, with the fastest change occurring somewhat after the closest and furthest approach, and the maximum and minimum to occur half way between. What I don't understand is why the change here so linear, either relatively constant cooling, followed by faster but also relatively constant heating. If there is something that can trigger such rapid (less than 1/8th cycle) changes, it must have a far more significant and powerful effect (at the turn around points) than the known feedback mechanisms I have read about so far. I assume it is either powerful (tectonics?) and/or fast (geologically) to have such a profound sudden affect. Please don't respond "it's not sudden if you expand the timescale of the graph", without explaining why the relative rate compared to the length of the cycle is not significant. All the feedback systems I know produces cyclic variations where the highest rate of change is mid cycle with lowest rate of change at the peaks - these graphs definately do not follow that norm. I would also appreciate not being asked to propose an alternative cause to CO2 (which I accept is a greenhouse gas); apart from the fact that lack of a suitable alternative idea does not validate a claim, I am here because I am not the one with the expertise. If I appear defensive, please forgive me, but these two (I believe invalid) counter arguments have been used the few times I thought this question may get adressed in the discussion. Seondly, I am confused by the label on the temperature axis for the first graph. The label says temperature change, but I assume it just means temperature, otherwise zero would be nearer the middle? -
muoncounter at 22:45 PM on 19 May 2012Galactic cosmic rays: Backing the wrong horse
ibir#125: "they might much more be able to stimulate release of a temporarily stored photons (~10um)," Muon-induced ionization does not result in photon emission: mu + atom -> mu + ion + electron (no photons here). Infrared wavelength photons (10um) are absorbed/emitted by molecular vibration. The molecules involved are GHGs: H2O, CO2, etc. Muons may interact with atomic nuclei, but not with such molecules. So that is not a valid mechanism either. Look at it this way: if muons interacted with greenhouse gas molecules, their flux rate at sea level would be a GHG detector. It isn't. -
Rob Painting at 21:47 PM on 19 May 2012David Evans: All at Sea about Ocean Warming and Sea Level Rise
chriskoz - halosteric are the changes in ocean salinity (saltiness) which affects the density of seawater and, ultimately, sea surface height. -
Bob Lacatena at 21:14 PM on 19 May 2012Polar bear numbers are increasing
matzdj, This issue is very simple. If warming continues unabated then eventually Arctic ice will melt for some or even large parts of the summer season. If this happens it is a destruction of the polar bear habitat for a very important part of their annual life cycle... it will shorten a hunting season that was already abbreviated by summer ice melt in 1970s conditions. For a human being, it would be like having a killing drought in August on every farm, every year for the next several hundred years (at a minimum). If you destroy an animal's habitat it will die or migrate. If it has nowhere to migrate, the only choice is to die... or to adapt and evolve, but I'm not sure that can happen when the habitat changes or disappears so quickly, and in any event, what would emerge would no longer be a polar bear. All of the evidence, no matter how sparse, points to a decline in polar bear populations, which is in keeping with all of the other science and observations (physics says the globe should warm, measurements show the globe is warming, measurements show the ice is retreating earlier and further each summer, etc.). But what really matters at this point is a measure in the change in habitat. One does not, after all, start to worry about drowning only when the water is already filling one's lungs. It helps to consider how deep the water is before diving in. Consider this report from the U.S. department of the Interior, which provides these graphs adapted from Durner et al 2009 (Predicting 21st-century polar bear habitat distribution from global climate models).
Observed changes in the spatial distribution of optimal polar bear habitat from 1985 through 1995 to 1996 through 2006. The map shows the net change in the number of months per decadal period where optimal polar bear habitat was either lost (red) or gained (blue).
Projected changes (based on 10 IPCC AR-4 general circulation models [GCMs] run with the SRES-A1B forcing scenario) in the spatial distribution of optimal polar bear habitat from 2001 through 2010 to 2041 through 2050.
Consider these other recent studies: Projected poleward shift of king penguins' (Aptenodytes patagonicus) foraging range at the Crozet Islands, southern Indian Ocean Monitoring sea ice habitat fragmentation for polar bear conservation Rebuttal of "Polar Bear Population Forecasts: A Public-Policy Forecasting Audit" In the end this all falls back, as usual, on the typical denial cry of "but it hasn't happened yet." Like most things related to climate change, however, if you can unequivocally prove that it is happening, then it is already too late. The climate will have gone too far, and there's no chance to stop it. This is the true danger of climate change. Climate change is slow. Historically, it takes thousands to tens of thousands of years. We're doing it in a geologic blink of an eye, but on human time scales it is still "glacially slow" (pun intended). But the CO2 we add to the atmosphere now commits us to a future that we cannot reverse. The CO2 we have added to the atmosphere has already committed us to a future that we cannot reverse. It bears repeating (that pun was unintentional): Like most things related to climate change, however, if you can unequivocally prove that it is happening, then it is already too late. This is true of polar bears. It will be true of many habitats and species that may be impacted by climate change, such as the Amazon, coral reefs, and many, many more. As thinking beings, we have two abilities that exceed those of other animals (like polar bears). One is to think and to project and to plan, to take what we know about how the world works, put 2 + 2 together, and realize what is likely to happen. The second is to look at what data is available, even for things that have not yet happened, and to make reasonable projections. This applies to every aspect of climate change. Loud cries of "but it hasn't happened yet" are made to prey upon those who are too stressed and tired about other, immediate problems in their lives to bother to think ahead. Thank goodness some people don't take such a conservative, short-sighted and ultimately failed approach towards how we manage our civilization and our lives. -
chriskoz at 20:30 PM on 19 May 2012David Evans: All at Sea about Ocean Warming and Sea Level Rise
The SLR on NODC website you're quoting is split into "theremosteric" and "holosteric" component. I found the definition of "theremosteric" online: it's as the name suggests the expansion due to change in T, other params (i.e. p) being constant. Howener the meaning of "holosteric component" evades me. I found some laconic definitrion of holosteric as "wholy solid", which does not make sense in our context as water is obviouslyt not solid. Can anyone explain to me the meaning of this component of SLR and why it is shown on NODC website as slightly negative (-1 to -2mm) for both shallow and deep ocean? Thanks. -
les at 18:56 PM on 19 May 2012Galactic cosmic rays: Backing the wrong horse
125 - ibir Physicist or not, you're speculating about physics and need a certain amount of background. First you said "not strong enough to create 'air ions'" now "able to strip electrons"... Molecules with stripped electrons are ions. etc. naybe there should be a post with more fundimental phulysucs concepts .. But, really, a good go at wiki is a mInimum and you could try to point a physics mechanisms outlined there. -
ibir at 17:55 PM on 19 May 2012Galactic cosmic rays: Backing the wrong horse
123 - les As a non-physicist, the maths is far beyond my skill, and, I wasn't thinking so much about Cherenkov radiation, just that when the charged muons are able to strip electrons from atoms/molecules, when flying by in relativistic speed, then they might much more be able to stimulate release of a temporarily stored photons (~10um), earlier then by chance anyway. -
R. Gates at 15:54 PM on 19 May 2012David Evans: All at Sea about Ocean Warming and Sea Level Rise
This is an excellent counter to David Evans and his cherry-picked denialist nonsense. The focus here on ocean heat content is spot on. You might want to update your 2000m graph as the latest data for Jan-Mar 2012 Is in and ocean heat content down to 2000m is at an all-time instrument record high. It is nearly impossible for skeptics to explain this away, so they can only discredit it or focus on the tropospheric temps. With Solar max 24 coming next year (no matter how weak) and a likely El niño in the next year or so, tropospheric temps should be hitting record highs as well. Skeptics will have to work harder to find cherries to pick, but expect folks like David Evans to be bringing us his little baskets filled as much as he can for as long as there are gullible and receptive minds to consume his psychotropic cherries. -
skywatcher at 13:43 PM on 19 May 2012Polar bear numbers are increasing
Those projections are based on what will happen if all the ice melts. That's like saying that we are in trouble if the sun becomes a supernova, and then worrying about it.
To raise a general point here - there is very strong evidence that summer sea ice is on a strong and accelerating decline (see appropriate threads). There is little doubt that sea ice will continue to retreat, most likely to seasonally ice-free Arctic within a few decades. The consequences are generally agreed to be a bad thing for the polar bear populations that rely on hunting on the sea ice. If you don't think sea ice is both thinning and retreating, and accelerating in its decline, discuss on an appropriate thread with your evidence. Conversely, there is no evidence that the sun will become a supernova. In fact the current consensus in astronomy is that the Sun is too small to ever become a supernova. Even if all the matter in the Solar system was condensed into a white dwarf, the degenerate star would not have enough mass to become a Type 1a supernova, and of course the Sun lacks a stellar companion to give the extra mass required to cross the Chandrasekhar Limit (about 1.4 solar masses) to make a Type 1a supernova. Other supernova types require even more mass. One idea is supported by nearly all the evidence we have, the other has no evidential or theoretical support whatsoever. Why would you make such a comparison?Moderator Response: TC: "IFF" is an abbreviation for "if, and only if". "IF" on the other hand is only a violation of comments policy. Your future compliance with that policy is appreciated. -
scaddenp at 12:50 PM on 19 May 2012Polar bear numbers are increasing
" Shouldn't we be applying those resources to problems that we know exist" Yes, we should. And despite your attempts to deny, without scientific foundation to support them, dealing with climate change is one of them and quite possibly the most important one. At very least it will many other problems worst. Please try looking at the evidence instead of trying to warp reality to fit a what appears to be a preconceived notion about the reality of AGW. -
scaddenp at 12:44 PM on 19 May 2012CO2 limits will harm the economy
So Helena, I take you agree that killing the subsidies is a good start, (you still seem to assuming that absence of data in the online database for developed countries means that most of subsidies are elsewhere,despite the OECD figures.) And lets not have high school debating tricks please about ducking the substantive question. -
Daniel Bailey at 12:26 PM on 19 May 2012Polar bear numbers are increasing
Using matzdj's logic one should let all bank robbers get away because not all bank robbers will actually leave the premises with the money after the teller hands it to them... Needless to say, matzdj's argumentarium is bereft of substance and replete with strawman rhetoric. matzdj, this website is an incredible resource for those actually interested in learning about climate science. For those of other persuasions, it is a tempting target. The choice of which path you are here to trod is before you now. -
matzdj at 11:44 AM on 19 May 2012Polar bear numbers are increasing
JMurphy, I stand corrected. I had taken that population of 5000 in 1950 as accepted data. I didn't understand that it may only have been a WAG. I guess we don't have a number to compare today's number with. The recent analyses from the PBSG group but seems to be reasonably well founded, although limited, at being around 20-25,000 Bears. However, their projections don't seem to based on that data, but on the fear of what might happen if all the ice melts. I think that defines a WAG. On the pbsg.npolar.no you can see the population status maps with comments. Davis Strait has about 10% of the total population and their comment is: "Population size of 2150 estimated using mark-recapture in 2007. Subpopulation likely increased over the last 30 years. Empirical birth and death rates suggest population is now declining." So the best data that they are willing to describe shows a likely increase. But a sample of birth and death rates (apparently too small a sample to document or lead to an updated population report) "suggests" the population is now declining. That led to a rating of Very High Risk of Future Decline. Boy that sounds like a weak reason to make such a strong projection. If there is more science or more data, why don't they describe it. I'm sure this group is doing good scientific work. However, they should limit their reporting to the data they have and how it projects. Now how it might project if something else changed. skywatcher and Composer99, I would like to stick with the science. The science from the PBSG is in their evaluation of the populations. i don't argue with that. But, If they were making projections solely based on the data they report, it is unlikely that they would come to the projections they discuss. Those projections are based on what will happen IF all the ice melts. That's like saying that we are in trouble if the sun becomes a supernova, and then worrying about it. I've been getting beaten up on other threads on this site because I am believe I saw something visually in the data that a statistical analysis didn't show because it averages things out. Where is the statistical analysis of the Polar Bear population that can be used to project their decline? scaddenp, I apologize for the rhetoric. What i was trying to say was that we have a limited amount of resources to apply to solving problems. Shouldn't we be applying those resources to problems that we know exist and that we can solve and will have benefit, instead of problems that we project because the data "suggests" that the problem "may" occur if some other event occurs. Let's keep watching the Polar Bear data and if it does ever show a decline in Polar Bear population, then we can consider worrying about it. Rob Honeycutt, (-snip-) DaveModerator Response:[DB] The topic of this thread is Polar bear numbers are increasing, not changes in sea-ice-extent minimums (cf this post on Kinnard et al 2011) nor about the opening of the Northwest Passage (another must-read is this post on Arctic sea ice extent).
Off-topic snipped.
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Rob Painting at 11:20 AM on 19 May 2012David Evans: All at Sea about Ocean Warming and Sea Level Rise
jsam - fixed thks. mfripp - not sure what you mean by 'human-generated heating', but the text has been slightly adjusted in any event. -
Martin A at 09:25 AM on 19 May 2012CO2 has a short residence time
IanC: Thank you for clarifying. Yes, I had been assuming linearity. None of the statements I had seen (eg "the adjustment time is essentially independent of the residence time") mentioned that they no longer apply if you assume linearity. Dikran M's paper uses linear systems as examples (if I have understood his paper correctly). He uses an example of a wash basin to explain the principle. I worked out the equations that describe it, assuming its outflow is proportional to the volume of water it contains. We have a wash basin, with: * i litres per minute flowing into it. * v(t) litres in the wash basin at time t minutes. * Outflow k v(t) litres per minute. (Note: outflow proportional to v(t) for linearity.) The equation for v(t) is then dv(t)/dt = -k v(t) + i Residence time In equilibrium (ie at t=infinity), dv(t)/dt = 0, so 0 = -k v(infinity) + i so v(infinity)/i= Residence time = 1/k. Adjustment time Consider the wash basin in equilibrium and then, at t = 0, dump an additional D litres of water into it at t = 0. The equation for v(t) is, as before, dv(t)/dt = -k v(t) + i, but with v(0) = D. This has solution v(t) = i/k + D exp (-k t) so the deviation from the equilbrium is d(t) = D exp(-k t) . This means that the adjustment time (ie for the transient to decay to 1/e of its initial value) is 1/k. Adjustment time = 1/k. So it seems that in the case of a linear model, at least one with a 1st order differential equation, residence time = adjustment time. And presumably, with some nonlinear models this may also apply? If you assume finite volume for the ocean, even with a 1st order linear model, the equilibrium changes after the injection of a mass of CO2 into the atmosphere. This means that a proportion of the released CO2 remains in the atmosphere forever (according to the model) - but I think that is different from saying that the residence time and the adjustment time are not equal. -
Jose_X at 09:06 AM on 19 May 2012Dear Heartland, Stop using Arthur Robinson's Trick to Hide the Incline
> >Regarding the world data. We clearly labeled this data location. Since virtually all other available dats (sic) from other locations (see Soon and Baliunas) is similar, providing this example was entirely ethical. Has someone followed up on this? [I haven't.] I wonder if doing the average on these studies would produce a mean similar to the pictured one. I think many MWP proxies do not line up temp with years, leading to wide error bars and lukewarm means. If that is the case here, then taking this one sample might not be "ethical" or accurate as concerns the implied depicted suggestion that the temp has clearly been higher in the recent past. -
jsam at 06:10 AM on 19 May 2012David Evans: All at Sea about Ocean Warming and Sea Level Rise
Typo alert. In "Evans can pretend the incoveniently long" there is an "n" missing, inconveniently. -
mfripp at 05:07 AM on 19 May 2012David Evans: All at Sea about Ocean Warming and Sea Level Rise
Albatross, we are in agreement. Nonetheless, it would be best if we avoid statements are inaccurate. Especially if it is easy to avoid such statements. -
Geo77 at 05:00 AM on 19 May 2012Dear Heartland, Stop using Arthur Robinson's Trick to Hide the Incline
I will definitely bookmark this post for future reference as an example of what constitutes denialism versus true skepticism. I hope that your work here will find it's way into the curriculum of some "methodology of science" type courses. You have provided an excellent and well documented example of how science should not be done. Or should we just call it anti-science, or in a nod to Seinfeld - science in the bizarro world? -
IanC at 04:56 AM on 19 May 2012CO2 has a short residence time
For more general functions for fluxes, X/F(X) and 1/F'(X) will probably be very different. -
Albatross at 04:55 AM on 19 May 2012David Evans: All at Sea about Ocean Warming and Sea Level Rise
mfripp @1, "There is volcanic activity as well as human-generated heating" True, but the magnitude of these terms is tiny compared to the incoming solar radiation. See "Heat from the earth's interior does not control climate" and "It is not waste heat". But let us not get distracted from the real issue. There real issue is Dr. Evans misrepresenting the data by cherry picking the data and ignoring corrections to the data etc. One has to wonder that had the corrections been in the direction of "cooling" whether they would have also been ignored by Evans? Surely he should know that no data are perfect (even the temperatures inferred from satellite MSU data and the ARGO data as Robert notes) and that all data have limitations and require corrections of varying degrees. "Skeptics" like to hold others to a very high scientific standard, as they should, but what is disconcerting is that Dr. Evans' video strongly indicates that "skeptics" are not willing to hold themselves to those same high scientific standards. Them failing to do so flies in the face of their claim about being true skeptics. -
IanC at 04:48 AM on 19 May 2012CO2 has a short residence time
@118 MartinA, I suspect the discrepancy is due to the use of a linear model to describe a process that is likely to be highly nonlinear. I think there is nothing wrong with trying to understand it via a linear model, provided that you interpret the results with care. Using X for atmospheric CO2, and Y for ocean CO2. The differential equations are dX/dt= -F(X) + G(Y) dY/dt= F(X) - G(Y) With F(X) and G(Y) being fluxes out of the atmos and ocean respectively. In your scenario, you initially assumed that the system is in equilibrium and then perturb X to determine the response. Suppose the system is initially in equalibrium (X*,Y*), i.e. F(X*)=G(Y*). Linearising the above system I'll get d(X-X*)/dt= -F'(X*)(X-X*) + G'(Y*)(Y-Y*) d(Y-Y*)/dt= F'(X*)(X-X*) - G'(Y*)(Y-Y*) The implication is if you want to treat the problem as a linear one, the time constants are actually given by derivatives of the fluxes with respect to concentration, i.e. how sensitive the fluxes are to a change in CO2. The equilibration time scale is given by 1/F'(X*). On the other hand, the residence time or lifetime is defined as as capacity divided by the flow rate, in our case at equilibrium is given by X*/F(X*). Intuitively this is sensible: if we have 100 tons of CO2 in the atmosphere, and it is entering the ocean at a rate of 100tons/day, it'll take about a day to clear the atmosphere of CO2. Now if the flux F(X) is linear in X as in your model, the residence time and equilibration time is exactly the same! The fact that you can't get a separation between the two timescales is due to your choice of F(X) and G(Y). -
Martin A at 03:49 AM on 19 May 2012CO2 has a short residence time
KR"The important thing to remember is that regardless of residence time, the vast majority of CO2 molecules entering the ocean are simply swapped with another molecule." Yes, completely agree. And if the system were in equlibrium, 100% of entering molecules would be swapped for an exiting molecule. "The rate of importance is how fast total concentration (not individual molecular identities) changes." Completely agree with this too. (...) At present I'm trying to understand simple idealised cases - I'm avoiding realistic situations as there are too many extra things to cause confusion. I'm working through DM's paper at the moment. "Again - the residence time is not directly related to the sum flow into and out of climate compartments, the adjustment time. That comes from the differences between flow rates." Again, I agree. Yet something does not add up for me and I reach a different final conclusion. I'm going to track it down - I promise. -
miffedmax at 03:14 AM on 19 May 2012David Evans: All at Sea about Ocean Warming and Sea Level Rise
Good grief. Even if the fuzzy, right-brained, marketing/advertising world where I work we know that "raw data" (as in marketing numbers, impressions, etc.) is just that. Raw. The idea that there are people who are so even clumsier with numbers than I am is frightening. -
mfripp at 02:43 AM on 19 May 2012David Evans: All at Sea about Ocean Warming and Sea Level Rise
The statement "Sunlight entering the upper layers of the ocean is the only means by which the oceans are directly heated" seems to be too strong of a statement. There is volcanic activity as well as human-generated heating. While these other means for directly heating the ocean are minor compared to sunlight, you might want to soften the statement to be more technically accurate. -
Adam C at 02:17 AM on 19 May 2012Dear Heartland, Stop using Arthur Robinson's Trick to Hide the Incline
It looks very likely to me that they plotted the 2004 data point and mislabelled it 2006, possibly by accident. This would make it an egregious example of cherry-picking rather than fabrication. If they were willing to simply fabricate the data, why would they have held themselves to a single point? -
KR at 01:46 AM on 19 May 2012CO2 has a short residence time
Martin A - The important thing to remember is that regardless of residence time, the vast majority of CO2 molecules entering the ocean are simply swapped with another molecule. The rate of importance is how fast total concentration (not individual molecular identities) changes. If you (from your intuitions) get this point wrong, you're going to obtain wildly wrong answers. As a rather brain-dead computation (an example - please do not consider this authoritative, as it skips so many factors): Currently oceans and the biosphere are absorbing ~2ppm of our slightly greater than 4ppm emissions. If the equilibrium for oceans and atmospheric CO2 is 285 ppm, we're currently at 395, and absorption rates are scaled by the imbalance from equilibrium, then 2/110 = ~1.8% of the imbalance is absorbed every year. That's the difference between ocean absorption and ocean emission via CO2 exchange. If we were to stop emitting right now, with that simple 1.8% decrease per year, we're looking at an e-fold (1/e) decay time of about 55 years. Not 5. Again - the residence time is not directly related to the sum flow into and out of climate compartments, the adjustment time. That comes from the differences between flow rates. -
John Hartz at 01:42 AM on 19 May 2012CO2 limits will harm the economy
Suggested reading: “Ka-Ching: Big Oil’s Mighty First-Quarter Profits: Keeping Tax Breaks for Biggest Oil Companies Is Ludicrous,” Center for American Progress, May 1, 2012 To access this article, including financial data for the 1st Quarter of 2012, click here. -
muoncounter at 01:20 AM on 19 May 2012Galactic cosmic rays: Backing the wrong horse
A recent senior thesis at MIT (not as good as a PhD thesis, but still no slouch), Quintero 2010 calculates the Cerenkov threshold energy for muons in air as 4.4 GeV; this depends on angle and index of refraction (n). It would thus be far more likely to see the Cerenkov effect as these particles pass through water (higher n). -
Philippe Chantreau at 01:16 AM on 19 May 2012CO2 limits will harm the economy
Helena's "it's always easier to take risks ("subsidies for risk-taking new ventures and startups") with other people's money." Well indeed, as that seems to constitute the bulk of the activity in stock exchanges these days... -
Martin A at 23:26 PM on 18 May 2012CO2 has a short residence time
DB Thank you for the link. I've downloaded the Bolin and Eriksson paper and I'm now reading it. It's often the earliest papers that give the deepest insight, perhaps because they had to sort things out from basics. Tom Curtis Thank you for the Archer recommendation. I have sent for a copy. From a quick peek via Amazon, if seems to be a descriptive introduction, avoiding the use of mathematics. It's quite true that life is to short to do everything but I'm determined to get to the bottom of the point I'm trying to understand in this case. So far as I can see, injecting a mass of CO2 into the atmosphere results in an exponential approach to a new equilibrium with a time constant equal to the avererage atmospheric residence time of a CO2 molecule. This seems to conflict with what I've seen in several places, including the statement at the top of this page. Dikran Marsupial Thank you. "the adjustment time is essentially independent of the residence time" This is the key point that I believe this SkS page makes, and which I have not been able to reconcile with my own intuition nor with my calculations of a simple model. I believe I have correctly formulated the differential equation, for my simplified case where there are zero emissions other than a one-off injection. [dx/dt = rate CO2 exits ocean - rate CO2 exits atmosphere, where x = CO2 in atmosphere]. I've emailed you a request for a reprint of your paper and maybe it will help me pin down the discrepancy between my understanding and what I've seen stated here and elsewhere. -
Dikran Marsupial at 22:34 PM on 18 May 2012CO2 has a short residence time
Martin A - if you can't access the paper itself, send me an email (at the address given on the publishers website) and I can send you a pre-print. My paper has a mathematical derivation of what you are looking for (at least a crude first-order approximation). I suspect the problem in your model may lie in the magnitudes of the steady state fluxes into and out of the atmosphere at equilibrium. Even when they are balanced, these fluxes are very large and are what causes the residence time (the average amount of time an individual molecule stays in the atmosphere) to be only 4 or 5 years (as the fluxes are about 20-25% of the volume of the atmospheric reservoir). However the rate at which the atmospheric concentration rises or falls depends on the difference between total emissions and total uptake, which is much smaller (about half the size of anthropogenic emissions), so the adjustment time (which characterises the rate at which the atmospheric concentration rises of falls) is much longer. As my paper shows, the adjustment time is essentially independent of the residence time, and focussing on the fates of individual CO2 molecules encourages one to "not see the wood for the trees). HTH -
Composer99 at 22:28 PM on 18 May 2012CO2 limits will harm the economy
With regards to It means the government is trying to pick winners instead of the market. Better to give citizens their taxes back and let them choose as raised by scaddenp In point of fact, due to a number of factors, most especially: (a) negative externalities of fossil fuel use (which are the main point of this site given its focus on the rapid global overheating caused by fossil fuel CO2 emissions) (b) the information asymmetry between producers & consumers of energy products (c) various perverse incentives that can exist when the interaction of energy producers & consumers results in collective action problems I would suggest that markets aren't very good at picking winners in cases where these three phenomena are at work: they are well-known market-distorting effects (negative externalities especially, since they lead to over-production of goods with externalized costs). IMO quite obviously, the fact that factor (a) is in play at all suggests that markets can easily pick - and stubbornly hang on to - 'loser' energy generation technologies. With regards to my point was that the 557 bn $ figure is money from countries that are free to do whatever they want, buying social peace through energy subsidies and allowing the development of the poorest being two examples as raised by Helena, I should note that not a lot of social peace has come from those energy subsidies taken on their own, then (e.g. Egypt & Saudi Arabia), and I am sure I would appreciate a reference showing that energy subsidies, in and of themselves, are sufficient to alleviate widespread poverty (especially when one considers the climate-related disasters that, say, Russia & Pakistan recently had to contend with). -
Helena at 22:09 PM on 18 May 2012CO2 limits will harm the economy
Muon, my point was that the 557 bn $ figure is money from countries that are free to do whatever they want, buying social peace through energy subsidies and allowing the development of the poorest being two examples. I guess scaddenp's point would be that it's always easier to take risks ("subsidies for risk-taking new ventures and startups") with other people's money. -
JMurphy at 22:00 PM on 18 May 2012Polar bear numbers are increasing
matzdj wrote : In the 1950's the population was about 5000. Anyone who brings up that number has obviously got it from somewhere dodgy, to be polite ! Either that or it has been taken without any checking or any real sceptical questioning. Have a look here for an investigation into that very suspect number. Actually, there isn't really any basis in fact for it. -
les at 18:45 PM on 18 May 2012Galactic cosmic rays: Backing the wrong horse
122 - ibir The 'shock waves' of relativistic particles is called Cherenkov radiation. It's quite easy, given the momentum of the particles, the refractive indecies etc. to work out the radiation spectrum... normally it's towards the ultraviolet and higher - you can then look at the absorption spectrum of CO2 etc. to calculate it's impact. Using e-m radiation to 'shake out' heat sounds interesting but I've no idea what that means. Stimulated emission? Something a bit fancier? Is this a totally wild idea? you'd have to do the maths to find out. -
ibir at 17:29 PM on 18 May 2012Galactic cosmic rays: Backing the wrong horse
Everyone use cloud formation as proof of connection between GCR and climate, whatever direction it is, as it is the one and only possible cause. What if there is another? In the lower region of the GCR energy spectrum, 10MeV-1GeV, where the flux is high, it is still able to create air showers of relativistic speed. In this region solar activity modulate the flux of a factor 10 between minimum and maximum. What if the shock waves of the secondary particles (muons mostly), even if not strong enough to create air ions, but to "shake the extra heat" out of water and CO2 molecules, in order to increase the loss of stored greenhouse energy. That is, making the night radiation into space to vary between solar minimum and maximum. Or put another way, solar activity modulate the degree of greenhouse effect. Is this a totally wild idea?
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