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bookworm at 02:48 AM on 24 April 2010The significance of past climate change
might be useful to look at the reverse situation. If climate had NOT changed significantly in the past, change skeptics would then be arguing that man could not possibly have any effect on world climate - that climate is self correcting in response to various challenges. The only overall conclusion from the fact of past change is that future change is possible. As other posts have pointed out the skeptic argument above is really a non-sequitur. reversing the situation helps people understand that. Only then get into the details - discussions of time scales and the like. -
kdkd at 23:54 PM on 23 April 2010Tracking the energy from global warming
Just to confirm, if I annualise the TOA/OHC data rather than have it in quarters like at the moment (actually over 9 years), neither the regression nor the correlation give statistically significant parameter estimates due to the loss of statisical power. -
Ken Lambert at 23:45 PM on 23 April 2010Tracking the energy from global warming
BP #67 Think I have got it. Excuse my slower engineer's brain. If we can name your charts Graph #60 and Graph #62, then am I right in assuming that your G#60 is the 'right' measure of OHC because the integral of the TOA flux fits the Argo 700m OHC? If so, then the diffence in slopes of the TOA integral between G#60 and G#62 represents the systemic error in the CERESflash flux. Taken over the last 6 years, your G#60 slope is -0.19E22J/yr and the G#62 slope is about +0.92E22J/yr with the difference being about 1.11E22J/yr. This converts to a systemic error of +0.69W/sq.m in the CERESflash flux. Could you then suggest why the 2000 - 2004 part of your G#62 TOA curve has a pretty flat slope of about 0.25E22J/yr, implying a much lower systemic error or if the error is constant at +1.11E22J/yr; a large decline in OHC for 2000-2004? -
James Wight at 23:44 PM on 23 April 2010Skeptical Science Housekeeping: flags, printable versions, icons and links... lots of links
Do the dates refer to the date the article was added to the database, or the date the article was published?Response: Published. It automatically prefills it with the current date but you can manually update it. It's not that big a deal for recent blog posts or mainstream media posts but for peer-reviewed papers published in previous years, good to get the year correct. -
chris at 22:11 PM on 23 April 2010Where is global warming going?
Yes, fine Peter, but it still doesn't address the point. If we want to assess Arctic surface temperatures as mspelto's point related to, then your response that "The "Arctic" has only one active GHCN station in Canada" is a non-sequitur. If we want to assess Arctic temperatures then the full set of Arctic temperature station data and satellite sea suface temperature data for the Arctic should be used (in fact the method by which NASA Giss assesses Arctic temperatures means that the Arctic data has some distance-scaled contributions from non-Arctic sites. I don't know the reason why Eureka was dropped. if you find out I'm sure we'd all be interested to know... -
Berényi Péter at 21:46 PM on 23 April 2010Where is global warming going?
#47 chris at 17:33 PM on 23 April, 2010 Peter, I was addressing your non sequitur I have mentioned Canada because GHCN artic station dropoff is most serious in that country. But we can get more specific if you wish. I have pulled off most recent GHCN v2 data at 2010-04-23 08:00 UTC from the GISSTEMP site. There are 108 stations in the database north of the Arctic Circle (66.5619° N). The distribution according to 1° latitude bands is as follows: 66 8 67 13 68 25 69 15 70 13 71 5 72 6 73 4 74 2 75 1 76 6 77 2 78 3 79 2 80 1 81 1 82 1 According to country: CANADA - 43 RUSSIAN FEDERATION (ASIAN SECTOR) - 25 NORWAY - 15 GREENLAND (DENMARK) - 10 UNITED STATES OF AMERICA - 7 RUSSIAN FEDERATION (EUROPEAN SECTOR) - 3 FINLAND - 3 SWEDEN - 2 Of these 108 stations 38 (35.2%) can be considered "active", ie. having data for January-March 2010. Latitudal bands: 66 2 (25% / 8) 67 5 (38.5% / 13) 68 8 (32% / 25) 69 4 (26.7% / 15) 70 5 (38.5% / 13) 71 2 (40% / 5) 72 1 (16.7% / 6) 73 1 (25% / 4) 74 2 (100% / 2) 75 0 (0% / 1) 76 2 (33.3% / 6) 77 1 (50% / 2) 78 1 (33.3% / 3) 79 2 (100% / 2) 80 1 (100% / 1) 81 1 (100% / 1) 82 0 (0% / 1) Country: CANADA - 6 (14% / 43) RUSSIAN FEDERATION (ASIAN SECTOR) - 17 (68% / 25) NORWAY - 7 (46.7% / 15) GREENLAND (DENMARK) - 3 (30% / 10) UNITED STATES OF AMERICA - 2 (28.6% / 7) RUSSIAN FEDERATION (EUROPEAN SECTOR) - 2 (66.7% / 3) FINLAND - 0 (0% / 3) SWEDEN - 1 (50% / 2) As you can see, station dropout rate in Canada Arctic is 86%, pretty high. I would rather not go into arcane details, just consider a single case, Alert, Nunavut. It is the northernmost permanently inhabited place in the world with not just an operational weather station, but also part of Global Atmosphere Watch. Still, it was dropped from GHCN in September 1991. It is not that data are not available. One can even download them in tabular format from Weather Underground for free. The closest active GHCN station is Eureka, 480 km away. Can you think of any valid reason it was dropped? -
chris at 19:59 PM on 23 April 2010The significance of past climate change
Chemware at 09:53 AM on 23 April, 2010 I'm not sure how seriously you're taking your graphs, but they're not teriibly helpful in relation to the expected/anticipated response of the climate system (temperatures; sea levels) to raised CO2 levels. The first graph tells us something about the response of the carbon cycle to raised earth temperature, and more specifically the temperature-induced redistribution of CO2 from ocean and terrestrial stores into the atmosphere. Your data indicates that if Earth temperatures rise by 1 oC, then the equilibrium atmospheric [CO2] levels rise by around 20 ppm. Since the glacial to interglacial earth temperature rise is 5-6 oC globally averaged and the glacial to interglacial [CO2] increase is around 90 ppm (from 180 ppm glacial to around 270 ppm interglacial), we get 15-18 ppm of increased [CO2] from a 1 oC temperature rise through glacial cycles; pretty much in line with your plot. (It's not quite so simple, since one must also factor in the feedback warming from the raised [CO2]. A similar problem arises with your sea level plot. Sea levels respond to temperatures. One can relate these causally to [CO2] levels only under the circumstance that the dominant influence on temperature is [CO2] changes (as is largely the case now). That wasn't the case during glacial-interglacial cycles, so the second plot has the same flaw as the first... -
Riccardo at 17:58 PM on 23 April 2010Models are unreliable
cloneof, you might be interested in this paper in press which specifically addresses Spencer and Braswell 2009 and to this discussion. Thanks to Ari Jokimäki at AGWObserver for informing us on this not yet published paper. -
chris at 17:33 PM on 23 April 2010Where is global warming going?
gallopingcamel at 13:53 PM on 23 April, 2010 No the NASA link is current right through to the present. Click on the Arctic region of the map on the NASA page I linked to. You will get lists of all the stations within 1500 km, and can select those that are Arctic ( >66 o N), and can discover which ones have data through 2010. There are quite a lot of these. The NASA Giss temperature for the Arctic is based on the full set (not just Eureka and Resolute). Berényi Péter at 15:41 PM on 22 April, 2010 Peter, I was addressing your non sequitur. If we want to address Arctic temperature station coverage, we should addres Arctic station coverage, not just Canadian Arctic station coverage.. -
Mikko at 17:05 PM on 23 April 2010The significance of past climate change
The argument: "Rising CO2 levels are an external forcing" would be easier to understand if you emphasize that the extra carbon is coming from sources of stocks of fossil carbon i.e. the carbon is coming in to the system (biospehere) from external sources (“carbon is coming into the system from under ground”). That is what is different in burning trees than burning fossils. In the first case you burn carbon that is already in the system (internal carbon). In the second case you burn carbon that is not in the system (external carbon). -
Ari Jokimäki at 14:54 PM on 23 April 2010Skeptical Science Housekeeping: flags, printable versions, icons and links... lots of links
Also, the "Latest climate articles & papers" could use an "all" option to all search parameters. -
Ari Jokimäki at 14:51 PM on 23 April 2010Skeptical Science Housekeeping: flags, printable versions, icons and links... lots of links
There was one thing I was missing. You used to have a good set of links to useful websites and such in the "Links" page but now it just contains the argument links. I just noticed that in the bottom of the Links-page there is a link that says "Links" which leads you to the old Links-content. That should be more visible somehow, I think.Response: I'll add it to the navigation drop down. Am going to have to come up with better names for everything - I can't call all these different pages "Links". -
gallopingcamel at 13:58 PM on 23 April 2010Where is global warming going?
It just struck me July 13 is the eve of Bastille Day. Given that we are talking about Canada, could there have been some celebrating going on? -
gallopingcamel at 13:53 PM on 23 April 2010Where is global warming going?
Chris (#39), The NASA link you provided cuts off at the year 2000 so you should look at more recent information: http://diggingintheclay.blogspot.com/2010/01/station-drop-out-problem.htm Ned has challenged me to find the reasons behind the station drop offs. With this in mind I am planning a trip to North Carolina during May. My correspondence with staff members at NOAA, Asheville and Environment Canada is going well but I still don't understand why so many stations have "dropped off". With regard to the Canadian Arctic, by 2004 only Eureka was left in the GHCN v2. Resolute appears to be back but I overlooked it as the station number changed. One of the problems with having so few stations is that METAR data errors can cause huge changes in NASA's anomaly maps of the polar regions. Berenyi Peter has already pointed to the "huge anomaly" of about 4 degrees Celsius for polar regions in March 2010. This anomaly may result from some strange readings at Eureka on March 29. This issue popped up on WUWT today. They found something similar on July 13, 2009: http://wattsupwiththat.com/ -
kdkd at 11:38 AM on 23 April 2010Tracking the energy from global warming
I'm still not sure that I understand this TOA/OHC stuff properly. So here's what I've done to BP's spreadsheet though: First to get OHC and TOA in the same units, I standardise them so that the mean is 1 and the standard deviation is 1. Now I run a linear regression model which comes out as: std(OHC) = 0.5 X std(TOA) + 1.4 E10-16 So for every unit that OHC increases, TOA decreases by 0.5. The adjusted R squared for this regression model is 0.22 indicating that TOA predicts 22% of the variance of OHC. The F statistic for the regression is 11.8 (df=1,37) indicating that the regression predicts better than chance. Next I move over to correlation because for a single variable correlation, it's equivalent, and slightly easier to understand. So the correlation between the two variables is -0.49 (p < 0.01) which is strong enough to convince me that autocorrelation isn't an especially big problem, although I lack the knowledge to examine that formally. The 95% confidence interval of the corelation is between -0.70 and -0.21. So what I want to do next is compare the performance of this regression against the UAH satellite data for tropospheric temperature anomaly. Again using standardised data for the 29 years data I have for the satellite record, the formula for predicting standardised temp anomaly from standardised atmospheric co2 is: std(temp) = 0.62 * co2 + 0.3E16 F(df=1,27) = 16.79, p < 0.001 Adjusted R squared is 0.36 The correlations are: 0.62 (95%CI = 0.32 - 0.80) So with 30 data points we're getting a similarly good prediction of some measures of the response to some climate variables to the OHC/TOA data. Now I don't have quarterly data easily to hand for the sattelite data or co2 levels, but I can just look at the final 10 years in the series to see how good that is. However for the data that I have to hand, with only 10 observations, the statistical power is so poor that the regression and correlation is not statistically significant. My conclusion is that the TOA/OHC data that BP presented is what we would expect for a moderately sensitive system with only a small number of data points - and thus limited statistical power. I don't think there's enough data to be able to draw conclusions about the relationship between OHC and TOA to global warming until quite a lot more data comes in. Meanwhile we need to rely on the temperature data, and the associated measures (e.g. ecosystem sensitivity etc) in order to use scientific data to formulate policy. -
HumanityRules at 10:45 AM on 23 April 2010Tracking the energy from global warming
67.Berényi Péter The OHC variablity looks seasonal. Have you tried averaging over a year? "On the other hand, net TOA flux should be very close to proportional to the time derivative of OHC, because there is no other heat reservoir in the climate system with comparable storage capacity." I started to think about the ability of the ocean to release energy. It's easy to imagine that at different times the rate at which energy is lost from the ocean varies allowing build up or loss of energy on a short time period which doesn't always match the incoming energy. -
Chemware at 09:53 AM on 23 April 2010The significance of past climate change
#55 Barry: very nice analysis and data, but it only covers the last 150 years. So the temperature is not in equilibrium as [CO2] is rapidly changing, and the whole climate system is far from equilibrium. That is, if we stopped emitting CO2 right now, the temperature would continue to climb for several decades-centuries. I was after the long-term, equilibrium temperatures, which I think are best obtained from paleo data, because the [CO2] is changing very slowly, and the climate is close to equilibrium. #57 Barry: Yes, this is the Vostok data, which I simply re-graphed to plot Temperature as a function of [CO2], over the last 100 kYears. #67 Chris: Yes, the same old Vostock data, combined (in Fig 1A) with Red Sea sea level data. But simple-minded experimentalist me has just taken the next step and said that if Temperature and Sea Level correlate with [CO2] (as Hansen's graphs clearly show), then let's just plot them against [CO2]. This is shown below. Re-plot of Vostok Ice Core data
Plot of Bard's sea level data against Vostock CO2 data
These are the sort of graphs that Engineers love: if [CO2] is X ppm, then I need to design for a Temperature of Y C, and a Sea Level of Z m.
While one must always be extremely careful with extrapolation, the goodness of fit and the slope of both graphs is very worrying.
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johnd at 08:26 AM on 23 April 2010Flowers blooming earlier now than any time in last 250 years
Given the First Flowering graph was based on UK data I wanted to relate the days of the year to how the seasons progress here in south eastern Australia. Here the autumn equinox happens on day 80, winter solstice on day 172, spring equinox on day 266, and summer solstice on day 356. In the northern hemisphere it follows that spring equinox happens on day 80, summer solstice on day 172, autumn equinox on day 266, and winter solstice on day 356. That means that day 140 on the first flowering index falls a full 60 days after AFTER the spring equinox and just 32 days before the summer solstice. That is certainly different to what we are used to on this opposite side of the world with the first flowering expected weeks BEFORE the Spring equinox. It would seem then that conditions that are global such as the solstices and equinoxes are less relevant than perhaps local conditions. Perhaps it comes down to the plants themselves, or the composition of the species, more spring flowering plants and less summer flowering. I realise it is the relative change that the article focuses on, but given the obvious differences between different parts of the world, it seems to be stretching credibility quite a bit to assume it represents what is occurring globally. -
scaddenp at 07:04 AM on 23 April 2010Skeptical Science Housekeeping: flags, printable versions, icons and links... lots of links
John, I might be missing the obvious but how do you find these links from the main page? Its not obvious to me. I would have expected this under Links (Resources) page, but no go. Is this just failing eyesight?Response: The navigation system needs a serious overhaul - hopefully the next housekeeping effort will include a bunch of navigation dropdowns drilling directly to all these hidden nooks and crannies. -
scaddenp at 06:45 AM on 23 April 2010Greenland's ice mass loss has spread to the northwest
Acushla - I think you are being suckered by misinformation. There are good historical documents for the Greenland colony - confined to 2 southern fiords and plenty of archeological evidence about the settlement too. The ice sheet was firmly in place then, as now. There is no possible doubt about this. -
Jim Eager at 03:39 AM on 23 April 2010Skeptical Science Housekeeping: flags, printable versions, icons and links... lots of links
VoxRat, you have to set the three search parameters at the top your self. -
tobyjoyce at 03:32 AM on 23 April 2010Skeptical Science Housekeeping: flags, printable versions, icons and links... lots of links
I notice that of the 18 "skeptic" articles or media stories from the last month, over half (10) are from Fox News(3), Daily Telegraph(3), Daily Mail(2) and the Washington Times(2). These organisations have a well-known political tilt. Two other organisations share that tilt, the Wall Street Journal and the Australian, which published 1 "sceptic" story each. Now, can anyone tell me if these were balanced with "positive" stories about climate science? I thought so. -
CBDunkerson at 02:36 AM on 23 April 2010Skeptical Science Housekeeping: flags, printable versions, icons and links... lots of links
Looking forward to the Android app. The peer reviewed feature is great, though I notice that the classification isn't 100%. For instance, one of the 'peer reviewed pro-AGW' items is a BBC blogger sounding off about how the 'evils of Climategate' are being whitewashed. On the flags, I'd suggest translating the tooltips into the relevant languages. "View skeptic arguments in Portugese" isn't much help to someone who doesn't speak English and might not recognize the flag of Portugal, but speaks the language... like say, most of Brazil. -
cloneof at 01:44 AM on 23 April 2010Models are unreliable
Riccardo Alright, thank you Riccardo. That totally cleared the things for me. -
Philippe Chantreau at 01:29 AM on 23 April 2010The significance of past climate change
Ther has not been a D.O. event for over 20000 years. Of all the known Bond events, only a small fraction had the potential to affect climate. They seem to lead to an opposite change in the other hemisphere, a phenomenon that has been dubbed the "bipolar see-saw." All in all, the resemblance with what's happening now is so poor as to be irrelevant. All that has already been discussed and referenced on this site before. -
barry1487 at 00:33 AM on 23 April 2010The significance of past climate change
I'm not clever enough to spot that kind of game unless I know the participants well enough. It occurred to me that Tom was being facetious. But it's better to assume straightforwardness if you're not sure when chatting amongst unfamiliars. Wasn't going to comment about that, but seeing as you mentioned it Chris... On another note, I find the reactiveness to skeptics a bit disappointing at times. Don't get me wrong, I've been as frustrated as hell quite often and been pretty abrupt, but I've lately seen well-meaning questioners mobbed with vitriol. I also hope that erstwhile obstinate interlocutors in these climate debates might eventually modify their approach, if not their doubts, if the door remains open. I ask myself "what's my purpose here" and try to operate as if the answer is meaningful. And I'm basically sick to death of the Punch and Judy. Seems to me it achieves the opposite of what is wanted (unless slap-downs are a turn-on for you). That's Nana's lecture for the year. Now back to our feature presentation. -
Riccardo at 00:17 AM on 23 April 2010Models are unreliable
cloneof, the video is a sort of short version of the paper. He calculated a possible cause of error in empirical sensitivity estimates based on random variability of some internal forcing factor. Tuning the variability with just satellite tropical data he found a lower climate sensitivity than the global sensitivities obtained by various GCMs. This is all it has to do with models, Spencer compares his sort of "tropical sensitivity" with GCMs. While the effect of random variability on short term empirical estimates of the sensitivity might in principle make sense, it does not make any sense when he compares his tropical sensitivity with GCMs. This paper is on the very same track of the more recent (and wrong) Lindzen and Choi 2009 paper, similar wrong reasoning that they sell as the definitive proof. -
Chris G at 00:00 AM on 23 April 2010The significance of past climate change
Tom, I meant no disrespect to BC, and I firmly believe that he gives an honest opinion. Above, I had presented the argument that there is a tendency in engineers, when you present information that only makes sense if something they have been assuming is a constant, is in fact a variable, they don't believe what you are telling them. BC, describing himself as an engineer, reported that he balked upon reading something that only made sense if the solar output was not constant, and then came to the incorrect conclusion that John was talking about changes related to earth's attitude or position. That follows very closely with the example I gave above. -
barry1487 at 23:59 PM on 22 April 2010The significance of past climate change
@Berényi Péter at 22:56 PM on 22 April, 2010Abrupt changes have been especially large when atmospheric carbon-dioxide concentration, insolation, and other important climatic variables were changing rapidly, with possible implications for general behavior of the climate system.
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VoxRat at 23:58 PM on 22 April 2010Skeptical Science Housekeeping: flags, printable versions, icons and links... lots of links
"So this allows you to check out all the skeptic peer-reviewed papers published in the last month. Or if you want to keep up with current views, check out the skeptic articles published in mainstream media over the last week." Both the links are to the same (mainstream media) list.Response: Oops, fixed, thanks! -
shdwsnlite at 23:42 PM on 22 April 2010Skeptical Science Housekeeping: flags, printable versions, icons and links... lots of links
Wow! I thought this site was pretty good when I first came across it. Now I am pretty much blown away by how much detail and depth of resources are here. Thank you again John for putting this all together, and thanks to those who help with the features of the site and to all those who contribute to the discussions. It has given me a much better understanding of just what is happening. Though some of the discussions are way out of my league I appreciate the effort to make this site comprehensible to all knowledge levels. -
Berényi Péter at 23:42 PM on 22 April 2010Tracking the energy from global warming
#65 Ken Lambert at 23:04 PM on 22 April, 2010 Can you explain Of course I can. However, I think I have already explained it, just give it some thought on top of reading sentences. The two TOA curves are essentially the same. The difference is a linear trend with a slope. The reason behind it is that TOA fluxes as measured by satellites (recently CERES mission) have large sytematic errors but reasonable interannual precision. At least as long as instrumentation does not change much and intercalibration issues are resolved. On the other hand, net TOA flux should be very close to proportional to the time derivative of OHC, because there is no other heat reservoir in the climate system with comparable storage capacity. Rapid large scale (back & forth) heat exchange between the upper 700 m of oceans and the abyss has no know mechanism, turnover time being several millenia. If climate system heat content is calculated from net TOA fluxes, only the second derivative is measured by CERES with reasonable accuracy, therefore heat content history has a free additive linear term. With OHC, on the other hand, the temporal inegral itself is measured. What I did was to choose the free term for best fit. It can be done for the last six years, but not before first half of 2003. This is the same period when ARGO float deployment was still at an early stage with poor global coverage and rather few floats compared to the target of 3000. At the same time older systems were already phased out almost completely. -
cloneof at 23:29 PM on 22 April 2010Models are unreliable
Riccardo I was going to write about the paper, but I actually found a good video where Spencer explains hi's paper. And at least he gives the impression that it is supposed to do something about climate models. http://www.youtube.com/watch?v=LpFk0zTW-ik -
Ken Lambert at 23:22 PM on 22 April 2010Tracking the energy from global warming
BP #60, #62, #64 I forgot to add - the NODC OHC data in your charts is only the top 700m of the oceans, Yes? If so, the hot topic is what is happening in Dr Trenberth's deeper oceans down to 2000m and beyond. With an average ocean depth of 3700m - there seems plenty of un-explored depth for more 'hidden heat' or is it 'hidden cold'. -
thpritch at 23:20 PM on 22 April 2010Skeptical Science Housekeeping: flags, printable versions, icons and links... lots of links
I am assuming that the paper you are referring to was listed as a "skeptics paper" because it is one that could be used by the deniers given their tendency to re-interpret peer reviewed research to fit their preconceived notions. In the case of the above referenced paper, the deniers could reinterpret the findings along the lines - "because this paper shows that CO2 warming can not account for a significant amount of the observed warming, the models must be wrong and none of the warming is caused by increased CO2 levels." -
Tom Dayton at 23:17 PM on 22 April 2010The significance of past climate change
Chris G and barry, I believe you misunderstood BC's intent. He was helping John by giving his knee-jerk reactions, to simulate an audience's immediate reactions upon seeing the slide presentation, to help John revise his slides to keep that audience engaged and on track. -
Chris G at 23:14 PM on 22 April 2010The significance of past climate change
Chemware, Barry, I believe Hansen et al cover this topic to some extent in "Target Atmospheric CO2: Where Should Humanity Aim?" http://arxiv.org/ftp/arxiv/papers/0804/0804.1126.pdf -
barry1487 at 23:13 PM on 22 April 2010The significance of past climate change
When the sun gets brighter - I baulked at this as my immediate reaction was that you are saying that the sun is emitting more energy. (With thought, I accept that your statement is correct because the sun gets brighter from our perspective because it's closer or the earth is differently tilted due to the Milankovic cycles) As I understand it, our sun has been getting hotter over the aeons. It's not a cyclical process.Even during its current life in the main sequence, the Sun is gradually becoming more luminous (about 10% every 1 billion years), and its surface temperature is slowly rising.
http://en.wikipedia.org/wiki/SunIn the long term, the greatest changes in the Solar System will come from changes in the Sun itself as it ages. As the Sun burns through its supply of hydrogen fuel, it gets hotter and burns the remaining fuel even faster. As a result, the Sun is growing brighter at a rate of ten percent every 1.1 billion years.
http://en.wikipedia.org/wiki/Formation_and_evolution_of_the_Solar_SystemThe continuous fusion of hydrogen into helium will cause a build-up of helium in the core. The rate at which this process occurs depends on the initial mass of the star and ranges from millions to billions of years. Larger, hotter stars produce helium more rapidly than smaller, cooler ones. The accumulation of helium in the core causes a gradual increase in the rate of fusion and gravitational self-compression, as helium is denser than hydrogen. Higher temperatures must be attained to resist this increase in gravitational compression and to maintain a steady state. Eventually, the core exhausts its supply of hydrogen, and without the outward pressure generated by the fusion of hydrogen to counteract the force of gravity, it contracts until either electron degeneracy becomes sufficient to oppose gravity or the core becomes hot enough (around 100 megakelvins) for helium fusion to begin. Which of these happens first depends upon the star's mass.
http://en.wikipedia.org/wiki/Stellar_evolution -
Chris G at 23:07 PM on 22 April 2010The significance of past climate change
BC #63, The energy emitted by the sun is not constant. There are, and have been over the ages, real differences in its energy output that have nothing to do with any orientation or orbital phase of the earth. Sorry, but I'm going to use you as a case in point that engineers often expect things to be constant that are not. -
Ken Lambert at 23:04 PM on 22 April 2010Tracking the energy from global warming
BP #60, #62, #64 Can you explain why the 2003-2009 TOA line from your Post #60 chart does not match the TOA line for the same period from the Post #62 Chart. The values on the energy axes (E22 Joules)are vastly different and so is the shape of the TOA curve, The OHC curve seem roughly the same for both charts. -
Berényi Péter at 22:56 PM on 22 April 2010The significance of past climate change
#21 chris at 00:05 AM on 22 April, 2010 they [Dansgaard-Oeschger events] are not representative of global warming/cooling events Think again. PNAS online Ice-core evidence of abrupt climate changes Richard B. Alley "Ice-core records show that climate changes in the past have been large, rapid, and synchronous over broad areas extending into low latitudes, with less variability over historical times." It is not "global warming" anyway, it is "climate change". And D-O events brought hell of an abrupt climate change for sure. With such an instability, current agriculture would be impossible, billions would perish of mass starvation. Even if such events can not happen in the present warm regime, it is well known at least 7 years worth of food storage is needed. Still, world economy is run on a "just on time" philosophy with less than a year food backup. Grim. -
The significance of past climate change
As an engineer I thought it behoved me to read and comment, so here goes. . When the sun gets brighter - I baulked at this as my immediate reaction was that you are saying that the sun is emitting more energy. (With thought, I accept that your statement is correct because the sun gets brighter from our perspective because it's closer or the earth is differently tilted due to the Milankovic cycles). When volcanoes erupt - my immediate reaction was we've had recent cases (Pinatubo, Krakatoa) where volcanoes have erupted and only caused very short term climate change. (I'm just giving you my first reaction here) So I was in a doubtful mood when I came to the second last paragraph. . the second last paragraph seems to be the key and I didn't find it convincing (Ie on a quick read. Similar to hearing it as part of a talk). It gave me the impression that there are a jumble of variables here and how would you know what's causing what and which variables are feedback. (Again with contemplation I start to realise what you are saying and how it does make sense. By the way, how can ice cores tell us temperature change and solar activity?) PS. I am not a skeptic on climate science. I live in a hot bed of activism on climate change and my daughter tells me you are giving a talk at UQ next month. I'll try and make it. PPS. I read a great comment in an IPCC article or related document about the greenhouse effect and saturation and the build up of pressure due to extra CO2 and the temperature of Venus being 400+ due to it being 98% CO2. I can't find it right now but I'd be really interested in your take on this topic as I didn't understand the build up of pressure bit and how it affects termperature. -
chris at 22:38 PM on 22 April 2010The significance of past climate change
Arkadiusz Semczyszak at 21:50 PM on 22 April, 2010 1. You are misrepresenting Lonnie Thompson's PNAS article, which shows that current warming is likely unprecedented in the areas studied for 5000 year. Since this is an open access article, anyone wishing to know understand this can read it here Note that this work is about mountain glaciers in S. America (Peru); the analyses presented are interpreted in line with similar data from mountain glacier cores elsewhere in the world. 2. You're misrepresenting the science on the LIA. It certainly wasn't "a rapid and permanent change of temperature in about a few years of at least circa 0.8 deg C". One can assess this by inspection of published data also in open access articles. See here, for example (Fig 3). On can only get "at least circa 0.8 deg C" if one goes from the "height" of the MWP to the "depths" of the LIA, and that took around 500 years (not "in about a few years"!). If one takes the more generally accepted temperature decrease to LIA (from around 1200-1600 AD), the temperature decrease was in the range 0.3-0.5 deg C. However one looks at this your interpretation is grossly incorrect. 3. Bond events. There's not much evidence that these are truly manifest within the Holocene. In any case since the last N. hemisphere warmish period was around 1000-1100 AD and the Bond events have a supposed 1500 year periodicity, we shouldn't actually be having a Bond event now at all. In any case you'll need to provide us with some evidence for Holocene Bond events. It's simply not possible to "explain the very existence of the current changes in temperature", without massiverly enhanced anthropogenic greenhouse gas levels. Making stuff up isn't going to aid our understanding! -
Marcus at 22:35 PM on 22 April 2010The significance of past climate change
Arkadiusz, another point. The little ice age didn't occur quickly. Reconstructions show a 0.8 degree fall in temperature over a period of around 600 years-a rate of -0.013 degrees per decade! By contrast, global warming since the 1970's has been at a rate of +0.16 degrees per decade-ten times faster! Also, the LIA is directly connected to both the Maunder & Dalton minimums-coupled with some volcanic activity, wheras recent warming has no solar connection. -
Marcus at 22:30 PM on 22 April 2010The significance of past climate change
Arkadiusz Semczyszak-1st Bond events really would only explain climate change in the Northern Hemisphere. 2nd, almost *every* Bond Event in the Holocene has resulted in *cooling* of the Northern Hemisphere, not warming (like the Iron Age Cold Epoch of 900BC-300BC or the 4.2 KYr event thought responsible for the collapse of the Egyptian Old Kingdom). 3rd, these cooling events have been relatively slow compared to recent warming. So one wonders how you think GLOBAL WARMING is in anyway consistent with Bond Events, when past Bond events-like the 30-year decline in solar activity-suggest that we should be moving into a modest global *cooling* event, if anything-not warming. The fact remains that the only thing consistent with the rapid rise in temperature the last 30-50 years is the equally large rise in CO2 & methane during that same time period. -
Marcus at 22:21 PM on 22 April 2010The significance of past climate change
John, according to my reading, pre-Quaternary global temperatures were frequently around 22 degrees C, around 6-8 degrees warmer than at any other point since. The only exception was a very brief period at the end of the Ordovician Era and again at the end of the Carboniferous Era-where temperatures fell to those closer to modern averages. Both climate change events were preceded by significant drops in atmospheric CO2 (from 7,000ppm to 4,000ppm between the Cambrian & Ordovician Eras & from 4,000 down to less than 1,000 over the course of the Devonian & Carboniferous Eras). What's important, though, is that even though the sun was around 10% cooler than the modern era, the planet's temperature was significantly warmer than today-& the only real explanation is the very high levels of CO2 in the atmosphere-CO2 that we're now re-releasing back into our atmosphere. Yet still some people would have us believe that this massive release can have *no* impact on our global climate. -
MarkR at 22:18 PM on 22 April 2010Skeptical Science Housekeeping: flags, printable versions, icons and links... lots of links
The 'skeptical papers' bit is a little weird. 'Is the basin-wide warming in the North Atlantic Ocean related to atmospheric carbon dioxide and global warming?' is hardly 'skeptical', unless you think that 'skeptical' means 'doesn't think EVERYTHING is CO2 related'! They conclude that CO2 warming contributes ~half of Atlantic warming - I don't see how this makes them a 'skeptical' paper, they're simply adding to a body of evidence on AMO & climate... -
Arkadiusz Semczyszak at 21:50 PM on 22 April 2010The significance of past climate change
"The past geological record indicates that changes on a global scale are invariably very slow. We're talking tens of thousands, to hundreds of thousands and even millions of years in the vast majority of cases." "The fact that virtually *every* natural climate change event in the past (with the exception of those caused by extremely massive natural disasters) has occurred at a rate of between 1/2 to 1/10th [???] of the rate of recent change is simply further proof that nature is not the cause of the most recent climate change event." ... This is a representation of knowledge - science, with a few years. At least. Repeatedly (here) I proposed-presented, a graph: http://www.pnas.org/content/103/28/10536/F4.large.jpg. Why? 1st L. G. Thompson is a definitely not a skeptic. 2nd Certainly his work only for Africa but (as one of the few) dates back to 2003. Please look at the changes in the eighteenth century. It is difficult to explain only the increase in volcanic activity in the LIA. LIA began, moreover, a rapid and permanent change of temperature in about a few years of at least circa 0.8 deg C. Chris - why? After all, there were no significant changes in ice surface ... Certainly the current change is unprecedented, but certainly no more violent than the old change! For example, according to v. Storch once looked like this: http://www.korthweb.de/PhZT/Temperatur_Intcal2.gif Moreover, the current temperature change fits neatly into the sequence of Bond Events (not to be confused with D-O). CO2 is not needed to explain the very existence of the current changes in temperature ... -
Berényi Péter at 20:54 PM on 22 April 2010Tracking the energy from global warming
#63 kdkd at 19:43 PM on 22 April, 2010 Is a csv file of the raw data available anywhere? I could not collect proper data files, so re-digitized both NODC OHC & CERES FLASHFlux (pp. 21) graphs. You can find the csv here. The dimension is 1022 J for both columns, offsets arbitrary, slope of TOA radiation imbalance as well (being the temporal integral of a function with offset unknown). Time resolution is three months. -
kdkd at 19:43 PM on 22 April 2010Tracking the energy from global warming
BP #62 Thanks. What's the cause of the difference between the TOA line in the first graph compared to the second graph? Is a csv file of the raw data available anywhere? I wouldn't mind doing some crude resampling stats on the time series.
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