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Comments 77551 to 77600:

  1. Trenberth on Tracking Earth’s energy: A key to climate variability and change
    DC#79: "it won't melt the ice caps" Ignoring all the stuff about photons and timing and 'evening out' for a moment, perhaps you would like to read Perovich et al 2008 or one of many other papers on the subject of melting Arctic ice. Calculations indicate that solar heating of the upper ocean was the primary source of heat for this observed enhanced Beaufort Sea bottom melting. Please find one of many threads on the subject for further comments.
  2. Trenberth on Tracking Earth’s energy: A key to climate variability and change
    Muoncounter #76: My post #77 (written before I read yours) and earth-climate.com makes it clear that I understand "feedback" and I also point out the rapid diminishing of such (by nearly 90%) for each up and down "trip" as well as the rapid timing involved for radiated heat, so that CO2 might, for example, extend the heat of the day by perhaps a few minutes at most, whereas the photons returning from other air molecules (as they physically rise much more slowly) have much more total energy and can extend the heat of the day for a few hours. Yes heat will transfer between molecules, not as much in gases as in solids, but it will "even out" the temperature in the nearby vicinity. So what? That warm air will then rise, cool off and emit more photons, half to space. It will never drift down to the surface against both the temperature gradient and the pressure gradient, so I don't care how long it stays up there: it won't melt the ice caps.
  3. Skeptical Science Helps Students Debunk Climate Myths
    Greetings, I also started using SkepticalScience for a similar activity in my Science & Global Change course: http://www.geol.umd.edu/sgc/docs/ClimateMythsTakeHome.pdf
  4. Trenberth on Tracking Earth’s energy: A key to climate variability and change
    DC#77: "why the heat of the day extends into early evening, but it usually cools by morning to (in calm conditions) the temperature supported by the temperature gradient from the core. " Please support this notion with something more than the Singapore example you've given on a prior thread. Where I live, the air temperature often remains warmer than the ground temperature. This varies by humidity (and GHG gas content), due to something called radiative cooling.
  5. Trenberth on Tracking Earth’s energy: A key to climate variability and change
    Thanks Jonicol. Yes I do realise O2 and N2 don't emit many photons, but as they rise and cool (perhaps eventually near the top of the atmosphere) they must release the energy in the form of photons at least when they get close to absolute zero. And the energy they carry represents about two thirds of the heat that came out of the surface as it cooled in the evening. The other third gets radiated back, about 70% of that being captured and half of that returning to the surface, then a third of that radiated up again etc. But each "return trip" is very fast and the radiated "feedback" is being reduced by nearly 90% each time. Also, since two thirds of the heat energy in the surface/oceans went into other air molecules (outnumbering CO2 by 2,500 : 1) there is still about half of that coming back, eclipsing that from CO2. This is why the heat of the day extends into early evening, but it usually cools by morning to (in calm conditions) the temperature supported by the temperature gradient from the core.
  6. Trenberth on Tracking Earth’s energy: A key to climate variability and change
    CBD#73: "Note on accompanying images: " Do you mean that 'there's no such thing as a greenhouse effect' simply because this particular wikipedia graphic omits it by design? Implying that 'net energy transfer' (wikipedia graphic) is not the same as 'global energy flow' (figure 1 here)? As if the word net means something important in this context? That would suggest that the figures are different because they represent different things. DC#74: "photons from individual molecules" Doesn't the energy of IR photons absorbed by greenhouse gases provide kinetic energy, which may either re-radiate or dissipate in collisions with other molecules? Isn't that molecular kinetic energy the basis (according to wikipedia) for 'temperature'?
  7. Trenberth on Tracking Earth’s energy: A key to climate variability and change
    CBD No. 73 The absorption by and radiation from gases other than the Green House Gases is very small indeed at any atmospheric temperature (200 K to 360K) (and this needs to be recognised Doug - O2 and N2 play almost part in absorption or emission of radiation {photons}) The reason is that the first excitable quantum state of these molecules is very much higher than the energy (kT) involved in collisional excitation. But those small numbers which they do radiate are not absorbed by the green house gases as Doug has stated. However, Doug's other point is very imortant and often overlooked. It is that most of the energy entering the atmosphere from the earth (~80% in fact) is from the wind blowing over the land surface (conduction land to air) - about 20% and evaporation over the vast oceans, ~60%, while about 20% is actually radiated and captured in the main by GHGs betwewen the ground and the tropopause. Most of it absorbed within a few hundred metres in the main, strong bands. Heat which is then reradiated (see 333 W m^-2 on K & T 2009 diagram) comes from all sources - direct absorption of radiation and collisional excitation in warm air followed by radiation. So once in the air, there is no distinction - heat is heat, excitation is excitation. This fact though is important when it is claimed that without the high levels of green house gases, the earth would be a whole 33 C cooler is certianly not correct. The air itself acts as a blanket and just as the GHGs absorb the ground radiation, they are almost solely responsible for cooling radiation in the upper troposphere and beyond. At heights where water vapour is negligible, well above the tops of clouds, carbon dioxide is the main radiator which is why its brightness measured by the satellites is roughly equivalent to 220 K. (This is probably not quite correct either, since at higher levels, the spectral lines are very narrow and the resolution of the satellite spectrometers were quite obviously not high enough, as would be expected, to resolve the structure in which the peaks of the lines may well have shown that the radiation is from a higher temperature than is apparent. So without any carbon dioxide, the earth would be expected to be a warmer place. A second important matter is that of the back radiation, shown in diagrams such as K&T above and reported as increasing with increased carbon dioxide or other GHG. This is not correct either since a fairly straight forward calculation, both analytically and numerically, involving the re-radiation from the layers of air, shows that irrespective of the radiation frequency, the increase in absorbed radiation closer to ground arising from increased GHG, provides a lower energy source to be sure, but this is exactly compensated for by increased absorption in the atmosphere before it reaches the ground. The intensity coming back to ground level is always I(0)/4, no matter what the absorption coefficient K might be where I(0) is the initial upwards radiation from the ground. Similar analysis of the transfer of excitation energy follows a similar pattern, even without taking convection into account. This of course is why when upwards measurements of radiation spectra, looking particularly at CO2, the intensity or brightness is consistent with the local ground level air temperature, as is also found by radiosonde measurements all the way up to the tropopause. Similarly you don't walk out in the afternoon from under the eaves and find yourself suddenly hit with 333 Watts/m2. What you experience iss radiation from molecules not very far away, many from only a micron or so in fact, very nearly in thermal equilibrium with the surrounding air, even though all of the radiative interactions are only via GHGs while the O2 and N2 molecules in much larger numbners, maintain collisional thermal equilibrium satisfying the Stefan-Boltzman Law. John Nicol jonicol18@bigpond.com
  8. Trenberth on Tracking Earth’s energy: A key to climate variability and change
    Yes, as explained on my site, about 7% (out of the 15%) come back to Earth, and within seconds about a third of those (2.3%) get radiated up, and 70% of those (1.6%) get captured and 0.8% go to Earth, then a third (0.27%) get radiated back up etc - doesn't explain "5.46 times". And it's all over in a few seconds and off to space or warm air rising. If you read up on Quantum Physics you'll realise photons from individual molecules have very specific frequencies, whereas those from solids have full spectrum IR. So only those from the surface can be captured by CO2 which captures its own unique selection of frequencies, related to spectral lines.
  9. apiratelooksat50 at 21:25 PM on 10 August 2011
    Climate Denial Video #3: Polluters Use Same Tactics As Tobacco Industry
    If even just 0.1% are qualified climate scientists, then 0.001 x 31,487 = 31.487 climate scientists who have signed the petition. We can then compare that to the 75 out of 77 who were deemed worthy of contributing to the oft reported 97% figure of climate scientists who support the AGW theory. 32 vs 77. Maybe, just maybe, things aren't as cut and dry as some would like them to be.
    Response:

    [DB] You should seriously rethink your maths here. 

    The phrase not even wrong comes to mind.

  10. Dikran Marsupial at 21:16 PM on 10 August 2011
    It's the sun
    Soons paper sounds to me like the results of a search for statistically significant trends and association with solar forcing region by region - which of course invalidates the test of statistical significance (unless multiple hypothesis testing issues are properly dealt with).
  11. It's the sun
    And besides,the paper was about *China* and about the 20's and 40's for some reason. It's not as if he's discovered something controversial about the *globe now* is it? Cheers.
  12. Trenberth on Tracking Earth’s energy: A key to climate variability and change
    DougCotton wrote: "This 30% simply warms the air molecules which then, as they rise and cool, emit photons which cannot be captured by carbon dioxide." Why can't they be 'captured'? Are they magic photons? :] As to the 'alternative energy budget' you present. You might want to include the disclaimer from the page in question; "Note on accompanying images: These graphics depict only net energy transfer. There is no attempt to depict the role of greenhouse gases and the exchange that occurs between the Earth's surface and the atmosphere or any other exchanges."
  13. It's the sun
    I've read the abstract of the Soon paper you linked to Eclipse. The temperature trends observed in China seem consistent with what is known about the 20th Century temperature trends in general IIRC - as a result of global brightening and dimming. So he may have that part right at least.
  14. actually thoughtful at 17:32 PM on 10 August 2011
    Skeptical Science Helps Students Debunk Climate Myths
    Maybe "A pirate" should take a hint from Professor Mandia and teach critical thinking.
  15. It's the sun
    This next argument seems to be another version of "It's the sun" that good old Willie Soon (and his $million from Exxon) have written. New Willie Soon paper Does anyone know any peer-review work on this yet? Is the journal it is in actually an authentic climate journal? Is it legitimate science about a LOCAL Chinese phenomenon or a hyped up local phenomenon that fraudster Denialists are using to try and confuse people about GLOBAL climate change?
  16. Trenberth on Tracking Earth’s energy: A key to climate variability and change
    Here's a graphic based on NASA information .... http://en.wikipedia.org/wiki/File:Breakdown_of_the_incoming_solar_energy.svg VERY different from the IPCC graphic!
  17. The Last Interglacial Part Three - Melting Ice and Rising Seas
    An interesting post, though the question is perhaps how fast can sea level rise given the vulnerability of WAIS and the prospect of surging Arctic amplification?
  18. Trenberth on Tracking Earth’s energy: A key to climate variability and change
    http://en.wikipedia.org/wiki/Earth's_energy_budget This Wikipedia page explains how, in the real world, about 15% + 6% = 21% of the total incoming solar radiation (that is, 21% of 340 = 71.4 watts per square metre) is actually radiated from the surface but double that (23% from the oceans and 7% from land = 30% in total) is in effect diffused by what is called "latent heat flux" from the oceans and "sensible heat flux" from land. This 30% simply warms the air molecules which then, as they rise and cool, emit photons which cannot be captured by carbon dioxide. The IPCC model shows 390 watts per square metre which is over 5.46 times the above 71.4 watts per square metre! Please explain the huge difference!
  19. Climate Denial Video #2: Failed at Science? Attack the Scientists
    "if radiation is the only source of heat for the atmosphere" Why would anyone think that? Note the other sources shown on the trenberth diagram, important especially very close to the surface. (good reasons for not trying to treat the atmosphere as a single slab).
  20. Skeptical Science Helps Students Debunk Climate Myths
    Phila, Many classical myths have at least some basis in fact. This one seems to come from another time and place altogether. `Twas brillig, and the slithy toves Did gyre and gimble in the wabe: All mimsy were the borogoves, And the mome raths outgrabe.
  21. Skeptical Science Helps Students Debunk Climate Myths
    Here's a brand-new myth for them to debunk: AGW is impossible because "energy can be neither created nor destroyed. So to look for input of energy into the atmosphere, you have to come from a foreign source." I believe I'll go and have a drink now.
  22. The Last Interglacial Part Three - Melting Ice and Rising Seas
    Thanks, Stevo. I'll have a fossick too when I have a few hours to rub together.
  23. The Last Interglacial Part Three - Melting Ice and Rising Seas
    Barry, The extinction of megafauna at the end of the last ice age is thought (by those I read many years ago when I was an anthropology student) to be the main driver of the neolithic revolution. No longer being able to rely on following the herds of huge beasts, man was forced to exploit other food souces. Smaller tools were developed to hunt smaller prey including birds and fish. I cannot recall anything signifigant from the previous interglacial. You raise a good question. I'll look around and see if I can find anything for you.
  24. The Last Interglacial Part Three - Melting Ice and Rising Seas
    Not really on-topic, but a bit related... I was musing on the notion that civilization has flourished in the current, steady interglacial, and wondered about human evolution during the last few ice ages cycles. Modern man evolved during a warm period (a degree or so cooler than present) about 200 000 years ago. Our species has survived two glacial maximums since. Is there any work in the literature linking temperate climate to evolutionary fecundity and/or increased biodiversity? Kind of opposite to the evidence of extinctions associated with 'rapid' climate change.
  25. Climate Denial Video #4: The favourite weapon of deniers, cherry picking
    I take your point, Bern, but am still searching for possible improvments in terminology. These days the net has given blogs the opportunity to mask science from the greater public. (All power to John for starting and running this site, BTW) The scientific side of the argument, rightly, adheres to constraints such as citing peer reviewed work and rules laid out in the comments policy used here. The other side does not. One feels like one is using the Marquis de Queenbury rules while the opposition is free to go open slather. Yes, the term "consensus of evidence" is good but the word "consensus" is too often used against us.
  26. Climate Denial Video #2: Failed at Science? Attack the Scientists
    In regard to the above doubts some seem to have about diffusion, consider what is the probability that, if radiation is the only source of heat for the atmosphere, that (in calm conditions at night) it just happens to raise that part of the atmosphere which is very close to the ground all the way from 0 deg.K (-273.15 deg.C) up to almost exactly the same temperature that it happens to be under the ground. (I hope this comment is short enough not to be snipped like the last few - I'm keeping screen captures as evidence.)
    Moderator Response: [muoncounter] Please note that threads are organized by topic. A more appropriate thread for your unique views on this subject is Tracking earth's energy. You might find Dr. Trenberth's article on radiation an interesting read.

    Make all the screen captures you like. Comments are not snipped for length, although few really long posts are worth wading through. Comments are snipped for violations of the Comment Policy, which you have already been advised to read and abide by.
  27. Climate Denial Video #2: Failed at Science? Attack the Scientists
    Scaddenp. Regarding predictions, the 900 to 1000 year cycles (correlating with eccentricity of Jupiter) and the superimposed 59.6 year cycles (correlating with the Jupiter/Saturn resonance cycle) and the further superimposed 11 to 13 year sunspot cycles all had maxima around 1998-2002 and thus predicted very well the warming period at the end of last century. They now predict the current trend since 2003, with a slight increase by the next sunspot maximum (June 2013) which will be the lowest since 1907 according to NASA. Then, as archived on my site, there are predictions of cooling from 2014 to 2027 then 30 years of warming and, eventually, significant cooling for another 450 years. etc. - read it there if you wish.
    Response:

    [DB] Off-topic portion struck-out.  This thread is about when climate "skeptics" can't win the scientific argument, they change tactics, smearing climate scientists and inventing conspiracy theories.  Please make a note that comments need to be focused on the topic of the thread on which they are placed.

    If the thread topic you are reading is not that of your comment, thousands of more relevant posts (some of which are likely to be about the topic of your prospective comment) can be located via the Search function in the Upper Left corner of every SkS page.

  28. Where have all the people gone?
    Eric @ 14 Two things suggest a speeding-up of SLR this century 1. Hansen et al 2011 note that we are already within “a few tenths of a degree” of the Eemian maximum when sea level was ~5m above current levels. Should we aim to limit atmospheric CO2 to 450 ppm, this would take average global temperature to well above Eemian by 2100 and so expose us to SLR similar to that pertaining at the Eemian maximum. 2. SLR is primarily caused by melting of land based ice. At current rates of loss, it is unlikely that SLR would exceed 1m by 2100. But why should we assume that current polar land based ice loss will remain constant for the next 90 years. If warming continues (few dispute it will) the rate of land based ice mass loss will increase causing accelerated SLR. Hansen asserts that the effects of slow feedbacks initiated by anthropogenic CO2 emissions are such as to produce decadal doubling of ice mass loss from the GIS. This would result in ice mass loss rising from ~120 gigatonnes in 2000 to ~130,000 gigatonnes per annum by 2100. Were this to occur and be accompanied by similar rate of WAIS ice loss, the result could be SLR of 5m by 2100. It is useful to remember that neither ice mass loss or its effect on SLR are linear and because of this non-linearity very rapid acceleration in SLR over the next 40-50 years would not be expected. During this period it is possible that SLR per annum will increase from mm/annum to cm/annum. However, during the latter part of this century a much larger SLR should be expected from on-going decadal doubling of ice mass loss from the GIS. I accept that most climate scientists at present regard a 1m. rise in sea level by 2100 as a maximum expectation and I remain quite ambivalent about a 5m SLR occurring by 2100. On the other hand, I see no reason to challenge the views expressed by Dr Hansen. Even taking into account uncertainties associated with slow feedbacks on Arctic amplification, it is not unreasonable to believe that SLR of no more than 1m. by 2100 is a very conservative estimate.
  29. A Detailed Look at Renewable Baseload Energy
    Peter Sinclair has a new item: Heat waves spotlight nuclear achilles heel On Wednesday, the utility had to bring a third reactor at Browns Ferry Nuclear Plant down to 50 percent power to avoid environmental sanctions because the water in the Tennessee River — where the plant’s cooling water is discharged — already was at 90 degrees. “When the river’s ambient temperature reaches 90 degrees, we can’t add any heat to it,” said TVA’s nuclear spokesman Ray Golden. ... All existing nuclear plants use vast amounts of water as a coolant. But in recent years — often far from the public eye — hot river and lake temperatures have forced power plants worldwide to decrease generating capacity. Experts say the problem is only getting worse as climate change triggers prolonged heat waves, prompting calls for changes in siting processes. Anyone see a feedback here? Long hot summer -> river temperatures over 90 degrees F -> nuclear plants reduce generation -> more gas and coal burned in FF plants -> more CO2 emissions -> increased temperatures. Add in drought -> reduced river flow and depth -> more rapid heating of water. Stir. Repeat.
  30. Climate Denial Video #2: Failed at Science? Attack the Scientists
    Firstly, let's just start with a quote from Wikipedia where yuo will learn what diffusion is between solid surfaces and gases - like the Earth surface and the first 1mm of the atmosphere. Or like my light shade experiment at http://earth-climate.com which no one here bothers to read. The following is linked a couple of times in my site: ( -Snip- )
    Response:

    [DB] Long, Off-topic perambulation snipped.

    Please note that posting comments here at SkS is a privilege, not a right.  This privilege can be rescinded if the posting individual treats adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum.

    Please take the time to review the policy and ensure future comments are in full compliance with it and also adhere to the topic of the thread that they are posted on.  Thanks for your understanding and compliance in this matter.

  31. Where have all the people gone?
    Yooper (response to #24): "meant as a retrospective look at the changes that could took place at some future point in time," Here's an aptly titled movie along the same vein. Why didn’t we stop climate change when we had the chance?
    Response:

    [DB] Thanks for the link.  Didn't know it was wholly available on the 'net yet (I caught an open-window preview back in the spring).  Highly reccommended.

    Postlethwaite was a treasure.  He will be missed.

    Edit:

    Ok, didn't realize that was just a preview (saw the 1:40 and thought that was the hour/minute runtime).  Oopsy.  Very much worth buying, though.

  32. Where have all the people gone?
    Tom Curtis - "On the other hand, I do want to firmly reject Agnostic's claim @11 that we might see a 1 meter rise in sea level by 2050" True, it seems very unlikely given the present state of knowledge, but 'suspected' rapid jumps in SLR during the height of the last interglacial, suggest that it is still possible, in principle at least. See: Rapid sea-level rise and reef back-stepping at the close of the last interglacial highstand - Blanchon (2009) If the timing/dating by Blanchon can be confirmed by other techniques, it's strong evidence of ice sheet collapse. Sure it's likely that collapse will take place further into the future, not in the next 39 years, but when you read what the bulk of scientific literature was saying 7-8 years ago, they've certainly made a habit of underestimating the speed of ice loss.
  33. Where have all the people gone?
    Tom Curtis: It seems we're mostly agreed that long-term (i.e. over 500-1000 years or so) sea level rises of 5-15 metres are not only plausible, but likely. Where I disagree with you, though, is your perception of rate. As Sphaerica stated at 17, it might be more appropriate to think in terms of ice melt per warming, rather than ice melt per century. After all, the end of the last glacial maximum saw a 5ºC temperature rise over 10,000 years. We're looking at matching that in 100 years. With rate of warming two orders of magnitude higher, it's not such a stretch to imagine that rate of sea level rise might be only half an order of magnitude higher. On that basis - I'd say that past performance is absolutely not a good indicator for what will happen over the next century, because the projected rate of warming does not appear anywhere in the paleoclimatic record, no matter how far back you go. This is the importance of models - they can give you an idea of what will happen when you venture into new territory. Models of ice sheet dynamics seem to be fairly rough & ready at the moment, but the more research done on it, the more worrying the results seem to get... (recent work on the PIG being but one example)
  34. It's not bad
    In a spirit of refinement: Under "Polar Melting" the last sentence (as I write) is "Melting of the Antarctic ice shelves is predicted to add further to sea-level rise with no benefits accruing." If ice shelves are floating ice (rather than land based ice), why would their melting per se particularly add to sea-level rise? What scientist has predicted that? Suggest removing that sentence. Sea level rise is covered under another bullet point anyway. (Yes, there could some side effect of speeding the adjacent land based ice's speed of travel to the sea - but that's more indirect and less solidly demonstrated and generally not what the sentence says or needs to say).
    Response:

    [DB] Thanks for taking the time to add to the discussion. 

    "If ice shelves are floating ice (rather than land based ice), why would their melting per se particularly add to sea-level rise?"

    Excellent, thoughtful question.  Obviously, floating ice itself cannot add to SLR as it melts.  A general answer is that the floating ice sheets of Antarctica act as buttresses, inhibiting/slowing the downstream flow of the ice sheet proper in response to gravity.

    A loss of the floating ice sheets will lead to the oceanic edges of the ice sheet to exposure to the much warmer waters of the Southern Circumpolar Current.  This will then lead to greater rates of calving at the leading edges, which then leads to an increase in icestream flow downhill.  This vector change in icestream speed eventually propagates upstream along the entire channel of ice.  The result is dramatically increased rates of calving of ice leading to the demise of first the WAIS (West Antarctic Ice Sheet).  Given enough warming and enough time, the EAIS (East Antarctic Ice Sheet) will also be vulnerable.

    Remember, the base of the WAIS and most of the EAIS are well below sea level.  The body blows the ocean can land without the blocking arms of the ice shelves can wreak terrible impact.

  35. There is no consensus
    Tom, Try here. http://www.eoearth.org/article/Energy_balance_of_Earth
  36. Where have all the people gone?
    DB @26, I'm certainly happy to concede that the WAIS will melt faster than Greenland. However, I return to my point about the past being the guide to the future. Similar situations undoubtedly occurred during the last deglaciation, and may have been responsible for some of the intervals of 4 meters per century sea level rise. Consequently multimeter sea level rises by 2100 cannot be excluded. But the average rate was still 1 meter per century, which I consider a better predictor. With regard to the mechanics of WAIS breakup, I think the sea is going to have to melt its way in. The weight of the ice will prevent it from simply running in under the ice and floating it away. Consequently the break up of the WAIS will certainly take decades, and will probably take a more than a century. Of course, all estimates come with large implied error bars ;)
    Response:

    [DB] I believe we are in broad agreement that:

    1. Past history is a general predictor of future performance
    2. That our current understanding of about 1 meter SLR is at about the upper limit we can expect by 2100 due to melt alone
    3. That the weight of the WAIS will prevent the warming oceanic waters from running underneath it as it does ices shelves/tongues.

    That being said, the constraining factor limiting the mass-wasting of the GIS, the coastal fringe of mountains, is entirely absent from the WAIS.  What this (warming plus geomorphology) entails for the WAIS is an enhanced Zwally Effect (surface melt running through moulins lubricating the bedrock promoting ice-sheet slip), creating an unstable ice sheet sliding at increasing speed down a slope that terminates in the ocean...(we need to drag Mauri in off the glacier he's on right now to provide some proessional insights).

    Basically, gravity (like physics) is a bee-otch and wins all ties.

  37. Where have all the people gone?
    DB @24, I certainly did not want to imply that you where suggesting Miami would be under the keel by 2100. Indeed, given the linguistic developments evidenced your story, I suspect you are placing it several hundred years in the future (without a specific number in mind). On the other hand, I do want to firmly reject Agnostic's claim @11 that we might see a 1 meter rise in sea level by 2050.
  38. Where have all the people gone?
    Michael Sweet @21, I am not particularly concerned about Miami's water supply, as it can be supplied by desalinization at need. As such it represents a low order problem for the future, and one which Miami has plenty of time to deal with. Bangladesh, and to a lesser extent the Nile delta (and no doubt others I am less familiar with) represent serious problems, which I do not wish to down play. They are resolvable problems. Bangladesh may well be able to defeat rising sea levels by building (with international aid) large sea walls now, along with other concrete baffles through out the delta. The idea is not to hold the sea back, but to retain more silt from flooding, thus raising the delta level. Alternatively the problems could be solved by either mass migration, or by urbanization coupled with enhanced agricultural productivity. The point is that if sea level rise were the only problem, the problem would be resolvable, and adaption would be a more economic response than mitigation. Of course, even for Bangladesh, sea level rise will be one of the least of their problems from global warming. Indeed, for Bangladesh some of their problems (loss of reliable irrigation due to glacier melt in the Himalayas, for example, or reduced primary productivity of crops due to excess heat) will make solving the problem of sea level rise more difficult if not impossible. So adaption only is not a viable response to climate change.
  39. Where have all the people gone?
    Sphaerica @17, the problem with indicating a sea level rise per degree celsius is that the paleo evidence clearly shows that it can take centuries, and even millenia to melt large ice sheets. The Laurentide ice sheet (over North America) for example, did not fully retreat until about 6,500 years ago, even thought the last glacial ended 10,000 years ago. Therefore the expectation that the Greenland Icesheet or the West Antarctic Ice Sheet should fully melt in 90 years is unrealistic. Should they melt completely, which seems likely with business as usual, that would result in a sea level rise of around 15 meters, (approx 7 from the GIS, 5 from the WAIS and 3 from other ice caps and glaciers), but it will not do so for several centuries. That means the sea level rise will be an ongoing problem for the foreseeable future, but not a catastrophic one for most people.
    Response:

    [DB] Tom, my understanding for the WAIS is that ice sheet collapse is the postulated mechanism of loss.  And that this is thought possible due to the WAIS being almost entirely accessible to the ocean, as the majority of its bed is well-below current sea levels.  With the PIG & Thwaites being the linchpin/keystone for the entire works.

    Thus, rates of in situ melt for the WAIS are completely moot.

  40. There is no consensus
    Eric the Red @374, I am going to need a citation for that claim. I have googled several articles articles written by Pidwirny, and none of them have the figures you show. Further, as Sphaerica points out, your quoted figure was for net thermal radiation (Surface Radiation minus Back Radiation), whereas Cotton and I where clearly discussing the Surface Radiation alone.
  41. The Last Interglacial Part Three - Melting Ice and Rising Seas
    SteveB#4: "once you factor in waves and tides. " True enough. But even the tides are quoted as so many meters above mean sea level. Your 2nd paragraph gives me the impression that you are talking about this 'static' topography; essentially the shape of the geoid, to which we then add the transient wave and tidal ups and downs. Don't mind me; I took a GIS course this summer, so I'm all awash with datums and geoids.
  42. Where have all the people gone?
    "I find it interesting that George R.R. Martin's Song of Ice and Fire fantasy series features background tension stemming from the idea that "winter is coming." " I wonder if this is favourite book for our sometime visitor - The Inconvenient "skeptic" who somehow believes a milankovich forcing can override all other forcings no matter how big.
  43. The Last Interglacial Part Three - Melting Ice and Rising Seas
    Paul - The Kopp et al paper I link to estimates a rate of 5-9 mm per year. muoncounter - you are totally correct if considering just stationary ocean surface topography. Local sea-level can temporarily be much greater than 2 m on a regional basis once you factor in waves and tides.
  44. Where have all the people gone?
    I would have to say that I also share Tom's skepticism over extreme rates of sea level rise. While this is attention-grabbing, I dont think it is supported well by science so far. Even with much higher temperatures, its hard to put much credence on projected sea level rise rates that are higher than peak rate for ice sheet collapse at the last glacial termination. On that basis, I doubt that sea level would be higher than 1m by 2100. While this doesnt have dramatic impact, it should be noted that 0.5m sealevel rise by 2100 is no laughing matter either (see the Stern report), especially for those places already having problems with coastal erosion and salt incursion. The great deltas in particular have a very delicate balance between sediment load and sealevel rise controlling dynamics.
    Response:

    [DB] Please note that I at no point (AFAIK) constructed any sort of time frame or amounts of SLR into this post.  Or at least into the intro piece.

    The intro was meant as a retrospective look at the changes that could took place at some future point in time, looking backwards from that time.  It serves(d) as an attention-getting device intended to spur dialogue.

    And yes, I was strongly influenced in this by The Road Warrior, The LOTR:FOTR and Earth Abides (by George R.R. Martin George R. Stewart).  Stories that will always live in my memories.

    Smiley

  45. Climate Denial Video #2: Failed at Science? Attack the Scientists
    I think we need a post on Postma. Chris? Doug, any new theory needs to perform at least as well as what it replaces. To start with, it needs to be able make testable predictions. I would like to see how your new theory goes in predicting the lapse rate for Earth, Mars and Venus for a start...
  46. There is no consensus
    374, Eric the Red, If you are getting your numbers from Pidwirny's article on energy balance of the earth where this diagram is just a revision of Trenberth's, substituting percentages for W/m2, then I'm afraid you are reading it incorrectly. In any event your numbers are incomplete. You are only accounting for incoming radiation (340) and not the greenhouse effect (which adds additional energy to the surface that must be accounted for). Either way, how does this in any way support your original contention that "scientists are placing too much emphasis on outgoing radiation effects in the atmosphere as opposed to convection"? Or are you openly withdrawing that comment?
  47. The Last Interglacial Part Three - Melting Ice and Rising Seas
    Minor point: "global sea-level is not the same everywhere and can vary by many metres from region to region" I thought measured ocean surface topography was on the order of 2 meters; most would say that 2 < many. Do the more recent data show more topography than this older satellite?
  48. The Last Interglacial Part Three - Melting Ice and Rising Seas
    How rapid was that SL fall? How rapid can the SL fall?
  49. Climate Denial Video #1: The Difference between Skepticism and Denial
    Bern @62: I actually like hearing Aussies speak in their native tongue. The background music on all of the TH videos was way too loud though.
  50. The Last Interglacial Part Three - Melting Ice and Rising Seas
    Excellent posting! Expected rate of SLR?

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