studiot Posted June 10, 2014 Posted June 10, 2014 You're disappointed that I want to check iNow's numbers and reference(s) for myself? Really? It's one reason using the quote person feature is preferred by many of us rather than the generic quote function, since it links back to the post in question, so we don't have to go searching for it. I can't find a mention of a 200m sea level rise prior to your post in a search of this thread, nor any recent post by iNow that mentions sea level rise at all. So disappoint be damned. I would like a link. I have already referred you to post#281, byiNow, where the figure 200m is writ large. Who do I report these unseemly attacks to, since they now appear to be personal?
iNow Posted June 10, 2014 Posted June 10, 2014 (edited) Here: http://www.explainxkcd.com/wiki/index.php?title=Main_Page The 200 m sea level rise given in the last panel for a "Cretaceous Hothouse" (i.e. if all ice on earth melted, including the Antarctic ice cap) could not be explained by this melt-off alone. If all the ice melted the water level would only increase by about 60-80 m, according to Antarctica, IPCC Third Assessment Report (section 11.2.3 on Greenland and Antarctic Ice Sheets) and Sea Level and Climate: USGS Water-Science School. Additional sea level rise can be expected from thermal expansion of seawater, and indeed the main reason for rising sea level at the moment is actually caused by this expansion of the sea due to increasing temperature. And here are the links referenced within: http://www.grida.no/publications/other/ipcc_tar/?src=/climate/ipcc_tar/ http://water.usgs.gov/edu/sealevel.html Again, though... Is anyone debating whether or not sea level rise is going to be a significant issue if we don't do something to change our emissions? As swansont highlighted, this anal and pedantic focus on 60m versus 200m seems to be little more than an attempt to distract from the core issue... We need to lower CO2, we should have begun to do so already years ago, and we need to act quickly. The title text notes that even with instant and aggressive emissions reduction, the temperature will still rise by roughly half an IAU (2ºC). While it says it's probably no big deal, this is a joke, because even the equivalent of half an Ice Age Unit of warming would cause a huge climate change. There was also this: What is sensationalist about suggesting Cretaceous sea levels were 200m higher than today? Published figures run as high as 250m. Arguably one of the most thorough analyses is this one by Muller that estimates a +170m level, 15% from the quoted number. Edit to Add: http://archives.datapages.com/data/specpubs/seismic1/data/a165/a165/0001/0050/0083.htm Our best estimate is that sea level reached a high point near the end of the Campanian (Late Cretaceous) about 350 m above present sea level http://www.sciencemag.org/content/310/5752/1293.short Long-term sea level peaked at 100 ± 50 meters during the Cretaceous <...> must be due to temperature changes that we attribute to tectonically controlled carbon dioxide variations So, perhaps we move on now? Edited June 10, 2014 by iNow
studiot Posted June 10, 2014 Posted June 10, 2014 (edited) iNow post#302 Again, though... Is anyone debating whether or not sea level rise is going to be a significant issue if we don't do something to change our emissions? As swansont highlighted, this anal and pedantic focus on 60m versus 200m seems to be little more than an attempt to distract from the core issue... We need to lower CO2, we should have begun to do so already years ago, and we need to act quickly. Do you not agree that figures should be accurate or that sources should be checked for veracity before being presented as fact? Edited June 10, 2014 by studiot 1
iNow Posted June 10, 2014 Posted June 10, 2014 Do you not agree that figures should be accurate or that sources should be checked for veracity before being presented as fact?Of course I agree, but also want to remind readers of the context. It was a cartoon, not a scientific journal. I shared it because the conclusions of the scientific journals are continually being ignored or misunderstood. Again... context. It was a cartoon, and it was largely correct... correct enough to get the point across clearly (or, so I thought... see previous reply from me to Tim).
studiot Posted June 10, 2014 Posted June 10, 2014 (edited) I don't usually award minus points but I did so this time for deleting something offensive after I had answered and referenced it in my post#303. Have you done any calculations on your supporting links to test their veracity, I am currently looking at the expansion aspect. Do you have any data for how deep the expected temperature rise would penetrate in 200 years and does that data discuss where the energy would come from to raise the water temperature nearly 10 degrees centigrade and how long it would take to perform this feat in a kettle the size of the world ocean? Edit : OK so here are some more calculations Taking the figure of 1.33x109 cubic kilometres of water from post#282 and the coefficient of cubical expansion of water, which can be found in any decent book of engineering tables as 0.000214 or here http://www.engineeringtoolbox.com/volumetric-temperature-expansion-d_315.html I calculate as follows For a rise of the whole ocean of 10 degress centrigrade the expansion is 1.33 x 109 x 0.000214 x 10 = 2.85 x 106 cubic kilometers. This figure is about 10% of the volume of ice available (again detailed in post#282) at 24 x 106 cubic kilometers. This does not agree with your statement in post #302 Quote The 200 m sea level rise given in the last panel for a "Cretaceous Hothouse" (i.e. if all ice on earth melted, including the Antarctic ice cap) could not be explained by this melt-off alone. If all the ice melted the water level would only increase by about 60-80 m, according to Antarctica, IPCC Third Assessment Report (section 11.2.3 on Greenland and Antarctic Ice Sheets) and Sea Level and Climate: USGS Water-Science School. Additional sea level rise can be expected from thermal expansion of seawater, and indeed the main reason for rising sea level at the moment is actually caused by this expansion of the sea due to increasing temperature. Edited June 10, 2014 by studiot
swansont Posted June 10, 2014 Posted June 10, 2014 I have already referred you to post#281, byiNow, where the figure 200m is writ large. Who do I report these unseemly attacks to, since they now appear to be personal? The report post function is at the bottom of each post frame, near the center. To the left of the MultiQuote and Quote buttons. The xkcd comic picture in post #281 mentions +200m sea level rise at +9 degrees celsius. Thanks for the pointer and the link. I didn't see that in the cartoon. (also for staff the numbering is off; for me that's post #285, probably because of posts that are not visible to everyone else due to moderation) edit: so to be clear here, we're debating a number claimed by Randall Munroe in a cartoon and not so much a claim by iNow (or myself, since I had also linked to the cartoon) where the emphasis was on the temperature difference between an ice age and 20th century norms. 1
studiot Posted June 10, 2014 Posted June 10, 2014 edit: so to be clear here, we're debating a number claimed by Randall Munroe in a cartoon and not so much a claim by iNow (or myself, since I had also linked to the cartoon) where the emphasis was on the temperature difference between an ice age and 20th century norms. I have no idea who or what Randall Munroe might be. I had understood that posters should not ask others to read links except as further information and that they posters should verify for themselves the worth of any link they offered. I further thought posters should refrain form personalising and adding emotively loaded sarcastic comments to their statements, which might otherwise be truthful. As regards to your comment on the thermal expansion of water I have presented my calculations for all to see.
iNow Posted June 10, 2014 Posted June 10, 2014 (edited) Your calculation assumes today's oceans volume will remain constant and that expansion over these temperature increases can accurately be calculated using this volume figure. That's incorrect. You need to adjust for the increased ocean volume we'll see due to melting ice sheets (which itself will increase with rising temperatures) and how this increased ocean volume will results in further increases in expansion... There will be more water to expand. Summary: You've assumed linearity in your model while trying to represent a nonlinear system. edit: so to be clear here, we're debating a number claimed by Randall Munroe in a cartoon and not so much a claim by iNow (or myself, since I had also linked to the cartoon) where the emphasis was on the temperature difference between an ice age and 20th century norms.Pretty much, yeah. Edited June 10, 2014 by iNow
studiot Posted June 10, 2014 Posted June 10, 2014 Your calculation assumes today's oceans volume will remain constant and that expansion over these temperature increases can accurately be calculated using this volume figure. That's incorrect. You need to adjust for the increased ocean volume we'll see due to melting ice sheets (which itself will increase with rising temperatures) and how this increased ocean volume will results in further increases in expansion... There will be more water to expand. Summary: You've assumed linearity in your model while trying to represent a nonlinear system. How much maths do you know? OK so add 0.024 x 109 cubic kilometers to 1.33 x 109 cubic kilometers and rework the figures. How much difference does that make?
swansont Posted June 10, 2014 Posted June 10, 2014 The issue has come up on the xkcd forum where they discuss the cartoon. There is speculation there, as well as here, that it's a unit mistake (feet instead of meters) and in deference to his snark about how we 'may be able to limit the temperature increase to 2 ºC, so no worries' (paraphrased), I refer back to my earlier comment. OTOH, Randall is usually very careful about detail. Maybe a cite will be forthcoming.
John Cuthber Posted June 10, 2014 Posted June 10, 2014 The cartoon (and let's remember- it is just a cartoon) refers to sea levels during the cretaceous period. This article says that's 170M higher than today http://news.mongabay.com/2008/0306-sea_levels.html And there are (as already pointed out) other estimates. 200 metres looks like a reasonable estimate to me- especially given the somewhat speculative nature of the issue. But I'd like to ask a few simple questions of those who worried bout the suggestion that it might not be the right figure. What percentage of the human race do you think lives between 0 and 60 metres above sea level and what percentage between 60 and 200 metres? Why are you worried about the future of one of those groups, but not the other? Isn't 60 metres enough of a disaster?
swansont Posted June 10, 2014 Posted June 10, 2014 I have no idea who or what Randall Munroe might be. He's the cartoonist whose number you were attributing to iNow. I had understood that posters should not ask others to read links except as further information and that they posters should verify for themselves the worth of any link they offered. I further thought posters should refrain form personalising and adding emotively loaded sarcastic comments to their statements, which might otherwise be truthful. If this is directed at me, you'll have to walk me through this. I was polite in asking for a cite and in pointing out that you had not yet accounted for thermal expansion. If my later was reply was somewhat curt, I will point out this was after you scolded me for taking you at your word that iNow had presented some number he should defend (as if a number in a linked cartoon should obviously be the poster's own work) and I couldn't find where iNow had done any such thing. Which, of course, never happened, because it was in a cartoon, not relevant to the ongoing discussion. So I'm not seeing the source of your umbrage. You made a mistake in the attribution of a number. We all make mistakes. Being offended looks to me like you're doubling down rather than admitting to it.
studiot Posted June 10, 2014 Posted June 10, 2014 swansont post 312 If this is directed at me No, If I had meant you I would have said so, although some of your remarks do not suggest even handedness to me. swansont post 312 He's the cartoonist whose number you were attributing to iNow. Are you suggesting that iNow did not put up post#281 or that he has no responsibility for its content or if neither, what are you suggesting?
Essay Posted June 10, 2014 Posted June 10, 2014 (edited) Sea level "changes" that speak about 200 meters is for an "ice-free" world, such as the Cretaceous 'hot-house' from 90-120 Mya (Cenomanian-Turonian), pre-Atlantic Ocean; and so the global ocean-basin volume was much smaller. === Today's total volume of ice in Greenland, Antarctica, and Mountain Glaciers, if melted, ...would contribute an additional ~70 meters to sea level, in today's ocean basins. ...iirc, from a recent climate science class. ...but we can run away from rising oceans. Acidification and erosion, and the consequent disruptions to the food chains and the agriculture that supports our societies, will be more difficult to run away from. ~ Edited June 11, 2014 by Essay
Phi for All Posted June 11, 2014 Posted June 11, 2014 ! Moderator Note I'm going to ask the participants here to all take a breath and refocus. There have been some misunderstandings, some defensive displays, some principle championing, some nit-picking, and some really great analysis of a controversial issue. Now let the breath out and decide where you want the rest of the discussion to focus. Thank you. 1
arc Posted June 11, 2014 Posted June 11, 2014 Sea level "changes" that speak about 200 meters is for an "ice-free" world, such as the Cretaceous 'hot-house' from 90-120 Mya (Cenomanian-Turonian), pre-Atlantic Ocean; and so the global ocean-basin volume was much smaller. Hi Essay, do we know that for sure? I have always assumed the ocean basin and continental land mass ratio has been relatively stable due to subduction occurring as some ocean basins reduce in size (as the Pacific Ocean currently is) while somewhere else a different ocean basin is enlarging as is the case of the Atlantic currently.
iNow Posted June 11, 2014 Posted June 11, 2014 How much maths do you know?Relevance? Your logic and underlying approach remains flawed and that's true whether I have 7 PhDs in mathematics or no training at all. The issue has come up on the xkcd forum where they discuss the cartoon. There is speculation there, as well as here, that it's a unit mistake (feet instead of meters) and in deference to his snark about how we 'may be able to limit the temperature increase to 2 ºC, so no worries' (paraphrased), I refer back to my earlier comment. OTOH, Randall is usually very careful about detail. Maybe a cite will be forthcoming.I have been looking for one and haven't seen one yet, but did see another suggestion by 2 posters that is parsimonious (in addition to the possibility it's a unit mistake): I would think 200 m is supposed to have been how much higher the sea level was during the Cretaceous period. It's listed right under the words "Cretaceous hothouse", a time when for instance North America was split by an interior seaway, and there were polar forests. For that, it seems to be accurate within rounding. Palms at the poles and +200m sea levels are not predictions, they're descriptions of the Cretaceous. Either way, this whole exchange shows just how ridiculous climate change discussions have become. They're the new creationism versus evolution. No matter how much data you share and no matter how many time falsehoods are addressed or rebutted and no matter how many questions get answered with rock solid evidence, the gish gallop continues and we waste energies that would be better spent looking for solutions and ways to minimize the hardship before us. We've seriously spent 2 pages going back and forth on a cartoon. I'd laugh if it weren't so sad.
studiot Posted June 11, 2014 Posted June 11, 2014 Thank you phi for all, I was hoping a moderator would intervene. +1 (post315) 1
Arete Posted June 11, 2014 Posted June 11, 2014 I was not attacked like this when, earlier in this thread I corrected a statement by Tim, although I did not join in the hounds baying at his heels in what seems to me to be a witchhunt. I don't necessarily think that it's a "witch-hunt". When one makes arguments as spurious as "Additional deaths will not occur due to increased frequency and severity of heatwaves, because people will take off their jumpers" and repeats it with no evidential support, one should expect some heavy handed criticism. Furthermore, if Tim had actually read the article, it would have spoon fed him a sensible rebuttal - "One study of US cities reported that an assumption of future adaptation, based on using analogue cities, reduced temperature-related deaths by 20–25% compared with no future adaptation." http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1469832/ http://jech.bmj.com/content/early/2014/01/08/jech-2013-202449.full#ref-29 So if he had of given that citation, and argued that with a projected 25% reduction in mortality due to adaptation, the real figure was closer to 3,750 deaths per annum and that the figure from the original article may have been inflated - he would have had a valid point. Instead, he chose to make take a stance that the paper was "bollocks" and that no one would die because of his own assertion that people would "take their jumpers off" for which he was rightly criticized. 2
iNow Posted June 11, 2014 Posted June 11, 2014 Additionally, none of us post here in a vacuum. Tim has a history at this site and has (with me, at least) long ago lost claim to the benefit of the doubt and any assumption of goodwill or intellectual integrity.
Essay Posted June 12, 2014 Posted June 12, 2014 (edited) Sea level "changes" that speak about 200 meters is for an "ice-free" world, such as the Cretaceous 'hot-house' from 90-120 Mya (Cenomanian-Turonian), pre-Atlantic Ocean; and so the global ocean-basin volume was much smaller. === Today's total volume of ice in Greenland, Antarctica, and Mountain Glaciers, if melted, ...would contribute an additional ~70 meters to sea level, in today's ocean basins. ...but we can run away from rising oceans. Acidification and erosion, and the consequent disruptions to the food chains and the agriculture that supports our societies, will be more difficult to run away from. Hi Essay, do we know that for sure? I have always assumed the ocean basin and continental land mass ratio has been relatively stable due to subduction occurring as some ocean basins reduce in size (as the Pacific Ocean currently is) while somewhere else a different ocean basin is enlarging as is the case of the Atlantic currently. At the risk of moving off-topic, or confusing a possible sea-level rise of about 200 feet (~70 meters) today, with a rise of 200 meters from 100My ago.... === Oceans back then were saltier (unrelated aside), as well as being more uniformly warm across their depth profile, so “expansion” may have been a bit more significant; however, oceans aren’t really very “deep” relative to their breadth, so the boundaries don’t affect the volume nearly as significantly as do changes in the depth. The average depth is about 4 kilometers, compared with an area of 361 million (square) kilometers; so the depth is ~0.002% of the breadth. Consider the changes associated with examples such as the Thulean Plateau, and similar buoyancy and subsidence events occurring over 70% of the planet’s surface; similar to mountain building or plateau uplift/subsidence on land, except on a larger scale. And of course the actual mountains of the spreading centers, along with the subduction and abyssal trenches also contribute to major changes in the volume of the basins; especially within the vertical scale of a few kilometers, so the effects are magnified when compared with changes in perimeter measured on the horizontal scale of millions-of-square kilometers. But I don’t know “for sure,” this is mostly based on university lectures and various associated books I’ve enjoyed; more or less mainstream views and traditional dogma. I agree that simply splitting the continents wouldn’t change the area of the ocean basins much, but it will add many new “deep” trenches. Add a few more trenches and a spreading center, as when a new ocean basin is created, and you can add or subtract a lot of volume without changing the total area very much. I did recently hear that the total area of the world’s deep ocean trenches was similar to the area of Australia! “These trenches are thought to equal an area the size of Australia….” “…and evidence of a new lost continent under the Indian Ocean are just some of the phenomena available in our oceans. It is also home to the longest and highest mountain range on Earth, with a combined surface area many more times vast than all the continents of the Earth put together.” ~ Edited June 12, 2014 by Essay
Tim the plumber Posted June 24, 2014 Posted June 24, 2014 Well, that's not true. You had a heat wave just last summer that claimed hundreds of lives. At the time of the article, the heat wave had lasted nine days. http://www.telegraph.co.uk/topics/weather/10187140/Heatwave-deaths-760-lives-claimed-by-hot-weather-as-high-temperatures-continue.html "Data has shown real risk of increased deaths when temperature goes above 26C." I await your next false and easily-refuted claim. The article is from June 2014. By yesterday, the country had seen five consecutive days of 30C-plus temperatures, making it the first prolonged heat wave since 2006. I accept that there are some deaths of people who are very vulnerable when it gets unusually hot but not many at all. In the UK we don't have domestic air-con. It's generally not something that is a significant risk. I'm quite sure 200 feet rather than meters is what was intended. The 1.5C to 4.5C temperature range represents the estimate for equilibrium climate sensitivity to a DOUBLING of CO2 or it's equivilant in radiative forcing. Since we will likely pass a doubling of CO2 over pre-industrial levels by mid century and other greenhouse gases such as methane and nitrous oxide continue to increase the radiative forcing produced by human factors will exceed that from a simple doubling of CO2. Are you suggesting that a further doubling is at all possible within any foreseeable time frame? If you are going to start talking about many hundreds of years or even thousands please have a think about how successful any forcast about human civilization would have been 200 years ago. 1814. How much do you think they would have predicted as the impact of air travel? At the level of denial we're seeing in places in this thread, quibbling over a factor of three is IMO silly, since it's not as if 60m is below some threshold we could deal with and 200m is over that limit. However, what about the thermal expansion of the water? You also need to account for that. (also, it'd be nice to know what post you were referencing, for context of the argument) Or we could not talk about all the ice in the world melting as it is not going to and use the predicted numbers that have come out of the IPCC or other bodies. The predictions are of a maximum of a 1m sea level rise by 2100. I find that number unaccountable high because I want to understand how it is arrived at and the mechanism which is expected to cause it. The IPCC uses the method of looking at the graph of the last centuries sea level rise (18cm) and saying that since this was due to the warming of the planet then since the next century will warm by more it will rise by more. Even when they do this they then add some more multiples which they need to get to the 1m level. I would like to see the degree of thermal expansion used as a start point ( it's about 7cm per degree rise by 2100) then look at exactly what ice is vulnerable to melting if there is a rise of "x" degrees. That's relatively easy to do if you only need a number with an accuracy of a factor of 2. By my limited reckoning, which is very basic and back of an envelope stuff, granted, the result will be a lot less than 2cm per degree. As I have said I would like to see an more detailed explanation of the mechanisms involved. How many million years ago was the cretaceous? So you have an accurate topographical/barymetric map of that time? You are a scientist so how can you compare data from millions of years ago with an event predicted to happen within 200 years? How can you be so certain that the topography will change so that such a rise is possible? If the topography does not change where will water equivalent to double the total ice come from, to bring this rise about? Thank you. When the child said "The king has no clothes on." It needed the some of the other people to start to laugh. If the kid was a lone voice then the consensus would have prevailed. Your calculation assumes today's oceans volume will remain constant and that expansion over these temperature increases can accurately be calculated using this volume figure. That's incorrect. You need to adjust for the increased ocean volume we'll see due to melting ice sheets (which itself will increase with rising temperatures) and how this increased ocean volume will results in further increases in expansion... There will be more water to expand. Summary: You've assumed linearity in your model while trying to represent a nonlinear system. The Atlantic is 4km deep. The Pacific is 6km deep. The expected rise by 2100 is at most 1m. I think we can ignore the mass change in calculations which are never going to need to be more accurate than 1mm. Is thinking about sea level to the mm at all sensible???? When ever I've been to the sea side the water has been bouncing up and down much more than that and trying to define the sea level to a mm of the sea right in front of me would be nonsensical.
swansont Posted June 24, 2014 Posted June 24, 2014 The article is from June 2014. I accept that there are some deaths of people who are very vulnerable when it gets unusually hot but not many at all. In the UK we don't have domestic air-con. It's generally not something that is a significant risk. The article is from July 2013. You need to look at date on the byline, not the "today's date" displayed in the upper right of the web page. "By Rosa Silverman 7:09AM BST 18 Jul 2013" False and easily-refuted, just as I expected. — "Some deaths". OK, now all we need to do is get you to take that tiny step to "more deaths if the heat wave is worse". The entire problem here is that that is not something that has been a significant risk in the past. If you do no mitigation, the number of deaths will increase. It's really not a hard concept, but you do have to throw out the inconvenience of ignoring facts or the idea that personal incredulity has any real validity.
Tim the plumber Posted June 24, 2014 Posted June 24, 2014 (edited) The article is from July 2013. You need to look at date on the byline, not the "today's date" displayed in the upper right of the web page. "By Rosa Silverman 7:09AM BST 18 Jul 2013" False and easily-refuted, just as I expected. — "Some deaths". OK, now all we need to do is get you to take that tiny step to "more deaths if the heat wave is worse". The entire problem here is that that is not something that has been a significant risk in the past. If you do no mitigation, the number of deaths will increase. It's really not a hard concept, but you do have to throw out the inconvenience of ignoring facts or the idea that personal incredulity has any real validity. And we have not had a heat wave since the article either. There are a lot more deaths in the UK from cold than heat. Old people like to retire to France or hotter places. We don't have domestic air-con. If it gets to be significant issue we will. Problem sorted. I get attacked for stating things in a normal English way where "heat is not a killer in the UK". Which is generally understood to be in a 99.9% way. Yes there are some exceptions. Those who post about 200m or 60m sea level rises or 9 degree temperature rises do not. THERE IS NO SCIENCE TO SUGGEST THAT SUCH THINGS ARE AT ALL ON THE CARDS. Why are my statements which are 99% OK attacked when such clearly grossly exaggerated numbers are left to float happily about? At what point does an exaggeration become a lie? I am wrong by a factor of 1% or so, maybe. When people put out claims that are misleading by a factor of 200 (1m becomes 200m) why no response? Edited June 24, 2014 by Tim the plumber
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