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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Comments 105051 to 105100:

  1. Climate change from 40 million years ago shows climate sensitivity to CO2
    Very interesting paper! Perhaps you could add a few clarifying words about the CO2 increase. The fact that there was not a strong signal in carbon isotopes is stunning. The source of carbon must be an different as in PETM (probably methanhydrates). PS Does anyone know why reasearch focuses so much on PETM? I havent heard of MECO until a few minutes ,while PETM is discussed for a long time in journals?
  2. Sea level rise is exaggerated
    Re: Karamanski (103) Not accounting for an additional rise due to an unknown level of thermal expansion, if it all goes at some unknown point in the future, Greenland contains enough water to raise sea levels by 7.2 meters while Antarctica (WAIS + EAIS) has enough to raise sea levels by 61.1 meters for a total of 68.3 meters (224 feet). Dunno where you got those figures (not cited in my powerpoint of the same name), but that total amount is approximately the vertical interval between the lowest of the sea levels during glacial max and that if all the ice melted. Perhaps that is what they meant. As far as thermal expansion, my understanding is that per each 1 degree C of ocean temperature rise will be accompanied by 1 meter sea level rise just from thermal expansion. Unless memory is deserting me. The Yooper
  3. Sea level rise is exaggerated
    What is the maximum possible sea level rise if all of the glaciers and ice sheets melted, and how much sea level rise can we get from thermal expansion? I read in "Global Warming FOR DUMMIES" that the maximum possible sea level rise from global warming is 650ft(200m) is this correct?
  4. Climate change from 40 million years ago shows climate sensitivity to CO2
    Miekol: "The fossil fuels that was once living organisms had to get their CO2 from the atmosphere, so early on the atmosphere must have been loaded with CO2." Even at a basic level that is incorrect. You are confusing carbon with CO2. A lot of CO2 would have been sequestrated by life at the time and held as carbon. As a poster pointed out you need to understand the carbon cycle. Apart from that, the faint young Sun and the CO2 thermostat would have taken care of long term CO2 effects and levels over hundreds of thousands of years.
  5. Compendium Maps: a visual summary of the climate debate
    Here are databases of climate research literature in a similar map format. Scroll down to 'Research Front Map'; there are four sub-topics mapped out. Another interesting feature is the Top 20 list. A few years back AAPT published 'famous physicist' and 'famous astronomer' trading cards; maybe someone can do climate scientists based on these lists.
  6. Climate change from 40 million years ago shows climate sensitivity to CO2
    From the article:
    During MECO warming, atmospheric CO2 increased to between 6,400 to 15,000 ppm.
    This statement misled me too. There is a peak in the algae estimates band in the CO2 graph at about 15000ppmv alright, but the red trend line seems to meander between 2000 - 3000ppmv as The Skeptical Chymist points out. It certainly never goes much above 4000ppmv.
  7. Climate change from 40 million years ago shows climate sensitivity to CO2
    #21: "this paper only measures the change in sea temperature at one site" The Eocene climate is quite well-researched. For further reading, here is a database of recent papers.
  8. The Skeptical Chymist at 22:17 PM on 6 November 2010
    Climate change from 40 million years ago shows climate sensitivity to CO2
    Re the increase in C02. Although this isn't my field I take it that C02 changes were found by measuring carbon isotopes in algae. The carbon isotopes showed a clear change demonstrating a large increase in C02, but the difficulty is in trying to convert this into actual C02 concentrations. How much the carbon isotopes change is apparently also dependent on phosphate concentration, so if you know the phosphate concentration you can get a more accurate determination of what the C02 change was. Their attempts to do this are shown in the light and dark grey bands in figure 1 above. By adding in more information they improved their phosphate concentration estimation and were able to get a better estimate of C02 increase (dark grey band which has lower uncertainty). This suggested a "rise in pCO2 by 2000 to 3000 ppmv" which is 2 to 3 times the baseline C02 of 600 and 1600 ppmv. @10 HM. AFAIK polar amplification is at least partially driven by the ice albedo feedback which didn't exist at this time (it was an ice free world). You are correct in noting that this paper only measures the change in sea temperature at one site, however as noted in the paper these results are consistent with previous measurements of the temperature change at this time from other sites
  9. What should we do about climate change?
    Peter Lang, Since you have not responded to my question about subsidies for wind in Texas I presume that you could find no subsidies. These extensive installations have been put in by the free market and reduce CO2 emisions now, not at some future time. The electricity they generate is billed when it is used at market rates. They are primarily limited by a lack of transmission lines. I doubt that Texans are subsidizing wind as you imply, it is the center of the oil industry and Texans are known to be anti-green. You must provide documentation for your extraordinary claim of wind subsidy in Texas. I am still paying monthly for the unapproved nuclear plant. Since you have not responded to my question about reactor safety in third world undeveloped countries, despite me asking it three times, I conclude that you feel that it is unsafe to build reactors in the third world. How do you propose the third world reduce their CO2 emissions, since they can't safely use nuclear? Your claim about R&D for established industries compared to new technology is absurd. On this web site it is expected that claims will be supported by documentation beyond what the nuclear industry puts out to support their position. You have convinced me that the nuclear option is limited in its ability to provide safe electricity to the world for the near term. Perhaps we can have this discussion again in 20 years if thorium reactors actually work and have a safety record we can examine. I have seen many similar proposals from nuclear proponents in the past that did not work and am skeptical about thorium. I would like to see a proposal for waste storage beyond "leave it to our children to take care of". I also don't like to see all the eggs in one basket, but your nuclear proposal looks like a bad idea that should go to the end of the line.
  10. What should we do about climate change?
    kdkd, Since you live in southern NSW you may have heard of Queanbeyan, yes? This should be of interest. Seriously, you should gain a lot of understanding from it.
  11. What should we do about climate change?
    kdkd, I posted before I was complete. Personally given the imperative to decarbonise, I'm wary of any solution that suggests putting more than half of the eggs into one basket :) Fair point. But surely that should lead you to do all you can to remove the blocks and imposts against nuclear. [don't forget wae presently have 80% of our eggs in the coal basket in Australia and 76% of our eggs in the nuclear basket in France. So I don't think this is a vaild point. I believe our requirements are: 1. security/reliability of supply 2. least cost 3. health, safety and environmental
  12. What should we do about climate change?
    kdkd, Well I have a solar thermal plant on my roof in southern New South Wales (an evacuated tube solar hot water system), That is not a solar thermal electricity generating plant. Not the same at all. Try this indicating that not everything has to be about electricity generation in order to reduce demand from the grid. The above link applies here too and also see David Mackay's 'Plan C' (see links on previous page) Next, once we add externalities, which demonstrate that fossil fuel technologies and renewables are of similar costs before we've realised economies of scale and technological advances relating to renewable technologies. Not even close. See my previous comment as to why you cannot directly compare the costs of electricity from intermittent generators with dispatchable generators.
  13. Climate change from 40 million years ago shows climate sensitivity to CO2
    RSVP, As you have been told numerous times before, for the climate to change there has to be a reason. Fireflys don't count. If orbital changes cause temperature changes, as has happened many times in the past, then CO2 rises as a feedback. If temperature goes down CO2 goes down. You appear to be deliberately asking stupid questions that you have been told the answer many times before. Read the basics before you post more questions that everyone knows the answer to.
  14. What should we do about climate change?
    PL #365 Well I have a solar thermal plant on my roof in southern New South Wales (an evacuated tube solar hot water system), and I can assure you that while it's not nearly as effective between the March and September equinoxes as it is for the other 6 months of the year, it's certainly no dud during that time. If it's cloudy for a week in winter we have to put the booster on for a couple of hours once every few days. Its winter effectiveness could be fixed by increasing the number of collectors by about 20%. Once you get to lattitudes more polar than say Tasmania, then winter effectiveness will be a serious problem. I see that CSIRO are currently commercialising domestic air conditioning technology based on solar-thermal and evaporative cooling principles, indicating that not everything has to be about electricity generation in order to reduce demand from the grid. Next, once we add externalities, which demonstrate that fossil fuel technologies and renewables are of similar costs before we've realised economies of scale and technological advances relating to renewable technologies. Nuclear on the face of it appears cheaper than both (including externalities), although the capital costs are very high in this case. The safety issues seem to be being addressed, but "safe non-proliferative nuclear" seems to be a couple of years off yet (although I could be wrong). The posts I've seen from you have generally tended towards you producing arguments aimed at confirming your assumptions. I'd like to see you producing an argument aimed at testing your assumptions, so that you can test the rigour of your point of view. Personally given the imperative to decarbonise, I'm wary of any solution that suggests putting more than half of the eggs into one basket :)
  15. What should we do about climate change?
    We interrupt your regularly scheduled fiction for a brief foray into reality: Solar Energy Generating Systems (SEGS) is the name of the largest solar power facility in the world (though there are more than a dozen larger ones now in development). It first began generating electricity in 1984 and was completed in 1991... without the 'massive' subsidies (for 'massive' read, "vastly smaller than fossil fuel subsidies") currently available. It has an installed capacity of 354 MW and has been providing stable baseload power (despite this supposedly being impossible for solar) at competitive prices (despite THIS supposedly being impossible for solar) while also generating a profit (again, supposedly impossible) since the very beginning. SEGS is 20+ year old technology and thus uses natural gas as backup when sunlight is dim; which results in about 10% of the power generated by the plant coming from natural gas vs 90% from sunlight... contrary to claims that solar power actually requires the installation of MORE fossil fuel power than would be required without the solar power. Which are, of course, so mind-numbingly ridiculous that it is difficult to imagine how anyone can take them seriously. This concludes our brief foray into the real world and things which actually exist. We now return you to your regularly scheduled nonsense about how technology will never improve to the point where such things (that have been around for 20+ years) would ever be possible. Have a nice day.
  16. What should we do about climate change?
    kdkd, There is an enormous amount of background to cover. I'd suggest you start at the beginning of this thread, read the rational posts and also read the links. There is a lot here. I have observed that most people who have commented on this thread have been constrained by their deeply held personal beliefs and have not been prepared to do objective research. So I am a bit jaundiced to start with. I wonder if you will be different. Will you do the objective research to discover about this important subject for cutting the worlds CO2 emissions from fossil fuel use? The current cost of solar thermal - in day time only and mostly in summer (it is next to useless in winter) - is about $225/MWh. USDOE has a goal to try to get solar thermal capable of baseload generation by 2030. NEEDS has a projection to get solar thermal to be able to provide 24 hour power by 2020. That is it is hoped it will be able to supply one day of full power by 2020; but this does not mean baseload capable because baseload would mean it could generate throughout long periods of overcast weather, dust storms, etc). The point to understand is the cost of energy from solar and wind cannot be compared with cost of energy from fossil fuels or nuclear without including the costs of the back up generators. The same applies to the externalities. In short, intermittent renewables have application for remote sites (but very expensive) and can make a small contribution to the grid. Anymore than a small contribution increases the cost of electricity from the grid substantially (I cannot quantify 'substantially' without defining many assumptions and constraints). We all agree it would be ideal to include more of the externalities in the cost of energy. And we have been progressively including more, mostly by regulating the emissions. However there are offsetting costs too, and in reality we have to achieve the best balance. There is a cost to society of raising the cost of electricity. Just look at the people who do not have electricity and look how they live to understand the costs of making electricity more expensive. I argue electricity should be as cheap as we can possible make it. See previous comments to understand why. I also argue that we can have low-cost low-emission electricity. We are blocking that by the polices we impose and we have been imposing for the past 40 years or more. But to understand requires opening one's mind!
  17. Climate change from 40 million years ago shows climate sensitivity to CO2
    Considering the correlation assumed between CO2 and temperature, it would seem that the less CO2 changed as a function of warming, the greater its effect. This of course rests on the initial assumption that climate change is driven by CO2, and not (for instance) the fire fly population.
  18. Climate change from 40 million years ago shows climate sensitivity to CO2
    Just wondering if there a position amongst those who truely believe CO2 drives climate, as to what would happen to CO2 levels if it simply got warmer for some other reason??? Would CO2 levels remain the same, go up, go down, etc.
    Moderator Response: Under modern conditions, which are quite well understood, CO2 is considered to be the biggest control knob of global temperatures, but not the only one. The sum balance of all forcings and feedbacks (of which CO2 acts as both) determines global temperatures. In the situation you briefly posit, rising temps would then drive a methane/CO2 release to some degree, driving a further warming response (a self-limiting mechanism, overall). If you wish something more specific in response, please posit a physics-based mechanism for your thought experiment for the group to discuss.
  19. What should we do about climate change?
    PL #363 There's unnecessary sarcasm in your reply. I may have spelled megawatt hour incorrectly, and I haven't been following the comments here terribly slowly for the past couple of weeks, so I'm afraid I'm not across the detail of what you've been posting. Anyway I don't know much about the topic, but I'm pretty clear that economics is far too anthropocentric a discipline to be taken seriously ;). I'm of the view that we should account for externalities to the maximum extent possible. Particularly where human activities can have long term unintended consequences. Anyway, we've established that the real cost of coal is approximately greater than or equal to the real cost of wind. How does it stack up with solar? Bear in mind that solar probably has quite a lot of distance to go before price and storage capacity is optimised, and it could well be entirely appropriate to subsidise this until it can hold its own.
  20. What should we do about climate change?
    kdkd, Your sacrism is noted. I am just wondering why you didn't look it up yourself given that I've postred the link about a dozen times so far? Since you clearly know a lot about this subject, could you explain which externalities should be internalised and which should not, and how you suggest we should internalise them? Why haven't we managed to yet given that we've been working on this for the past30 years? You forgot to mention what is the cost to society of higher cost electricity? Also, for my benefit, could you please explain what is a MwH?
  21. What should we do about climate change?
    PL #359 (the funniest three digit number according to Douglas Adams fwiw). You need to quantify your statement, not just throw out assertions. Actually in this case I don't. I just needed to point out the hole in your argument. Which leads to #361 and thank you for doing some research. According to my calculations, from the main table on page 13, firstly the external costs of fossil fuel power is aproximately an order of magnitude greater than for the non-fossil technologies. The average external cost for coal is somewhere between €40 and €75 per MwH ($USD 55-105 per MwH). The average externalities for the other technologies (including nuclear) are going to be around 5-10% of this value, and gas is around 25% of the coal externality for reference. I have no particular nuclear axe to grind, but I'm quite keen on the idea of efficiency through distributed power generation, and not putting all of our eggs in one basket (with the proviso that we should decarbonise as quickly as possible). Again, thanks for doing some research :)
  22. What should we do about climate change?
    kdkd, Here is European data on the externalities for the different electricity generation technologies (see the two tables on page 13)
  23. What should we do about climate change?
    KR, I agree nuclear was heavily subsidised in the past. So were hydro and fossil fuels and renewables (and still are). But this doesn't change the fact that you have to make comparisons on a properly comparable basis. The link provided the annual subsidies by governments. Therefore, to obtain a proper comparison you need to divide the subsidies by the amount generated in that year. If you want to life time subsidies you need to get the life time subsidies and divide by the life time energy generated by the technology. A couple of other points. Much of the subsidies for nuclear were for military purposes not civil. The total subsidies would need to be split in the appropriate proportions if you want to compare lifetime subsidies. The other point is the figures in the link to not contain the major component of the renewables subsidies (see my previous comments on this, e.g. #353).
  24. What should we do about climate change?
    kdkd, You need to quantify your statement, not just throw out assertions. How much higher? You also need to factor in what is the cost to society of higher cost electricity.
  25. It's cooling
    Found this poking around on Kelly O'Day's site. Data through 10-26-2010. The chart can be found here. The Yooper
  26. It's cooling
    Re: erikbays (71, 73) Your claim was that:
    "According to the NAS even surface temperatures from proxies like tree rings are not that reliable earlier than about 500 years ago. But there is no way at all to get total ice volume or temps from specific layers of the ocean from the medieval warm period or earlier."
    This claim is addressed both in the linked post you were given as well as linked from there directly to this 161-page NAS document, 'Surface Temperature Reconstructions for the Last 2,000 Years'. I would direct your attention to FIGURE S-1 on p 17 and then these quotes from the summary on p 18:
    "It can be said with a high level of confidence that global mean surface temperature was higher during the last few decades of the 20th century than during any comparable period during the preceding four centuries."
     and
    "Less confidence can be placed in large-scale surface temperature reconstructions for the period from A.D. 900 to 1600."
     Less confidence does not mean unreliable or no confidence. Compare the confidence expressed in those two quotes to that in this (also from the summary on p 18):
    "Very little confidence can be assigned to statements concerning the hemispheric mean or global mean surface temperature prior to about A.D. 900 because of sparse data coverage and because the uncertainties associated with proxy data and the methods used to analyze and combine them are larger than during more recent time periods."
     So, the NAS has little confidence in surface temps prior to A.D. 900, and high confidence in temps post-1600 A.D., with temps 900 - 1600 A.D. falling somewhere in-between, confidence-wise. This, based on multiple, converging lines of evidence. Thus, the post you were directed to did indeed refute your claim. I believe that is why the Moderator directed you to the prior post. I'd recommend reading the entire NAS report. There's some good stuff in there. If your point was otherwise, I'd recommend re-phrasing it more narrowly & resubmitting it. Hope that helps. The Yooper
  27. What should we do about climate change?
    I will point out that nuclear power plants were heavily subsidized when first developed. It's a bit hard to compare the situation of a relatively mature technology (at least for once-through light water reactors) to wind farms that are still somewhat in development as major grid sources.
  28. What should we do about climate change?
    Peter Lang #353. "The LCOE for New coal plants is around $50/MWh and much lower for existing plants." This is with the externalities being given a value of $0/MWh. Once you price the externalities properly, this figure should be much higher. Not only CO2 emissions, but other forms of damage caused by mining itself.
  29. It's cooling
    So after my post @ 71 it says my statement is addressed on the hockey stick page. Yet the hockey stick page does not talk about total ice volume or total heat content. I think someone was missing the point of my comment.
  30. What should we do about climate change?
    Regarding the cost of electricity from nuclear and renewables http://www.iea.org/Textbase/npsum/ElecCost2010SUM.pdf IEA, “Projected Costs of Generating Electricity – 2010 Edition; Executive Summary” compares the Levelised Cost of Electricity (LCOE) in North America, Europe and Asia Pacific by generator technology. Note this comment: Neither does the study include other systemic effects such as the costs incurred for providing back-up for variable or intermittent (nondispatchable) renewable energies. For the calculation of the costs of coal‑fired power generation with carbon capture, only the costs of capture net of transmission and storage have been taken into account. In other words, the costs for wind (and other renewables) do not include the cost of back-up and the cost of Carbon Capture and storage is meaningless because it is for the capture part only and does not include the transmission and storage.
  31. Climate change from 40 million years ago shows climate sensitivity to CO2
    #14: Sorry if you found my replies harsh. Your earlier comment So what? So what nothing! didn't give me the impression you were 'still collating'. "ALL of the history of the planet must be factored into the discussion" Yes, that's called geology. Please check the prior articles 'CO2 was higher in the late Ordovician' and 'CO2 was higher in the past' for some context for your thinking. Be sure to recall that paleogeography is a controling factor in both oceanic circulation and the degree to which the planet can sustain glaciation; plate tectonic activity (or the relative lack thereof) produces both CO2 and aerosols; carbonate deposition in warm shallow water has the capacity to suck huge volumes of CO2 out of the atmosphere. Oh, and did I mention there weren't any flowering plants in the Ordovician?
  32. What should we do about climate change?
    Moderator, you might like to take a look at #343 and #346 for example, and perhaps reinstate my responses. My responses were to a succession of such comments - from people who think they are objective and dispassionate, but are far from it.
    Moderator Response: Given the overall nature and tone of this thread, emotions have been running a little high. Comment 343 is more egregious than 346, but is in that gray area in the Comments Policy, toeing the line but not openly violating it. As such, the Moderator at that time allowed it. By focusing on the content of your own comments and being mindful of tone when replying to others comments, despite any perceived provocations, we all will benefit from what you have to offer here. If you see another's comment that is in open violation of the Comments Policy, do not reply to its content, but bring that comment to the attention of the Moderator instead. Thanks in advance for your content contributions to SkS and compliance in this matter. Both are appreciated.
  33. What should we do about climate change?
    Moderator, I notice you are deleting some of my replies, yet comments like this remain from the anti-nuclear, pro renewable advocates. "Your shrill claims with little documentation are unconvincing."
    Moderator Response: Your comments that were deleted were in violation of the Comments Policy, containing insults, ad hominems, politics and being off-topic. Keep it clean and on-topic for that particular post and comments stay. You are not being singled out; others, too, experience this and learn in time to communicate their positions in their statements more effectively. To everyone's benefit.
  34. What should we do about climate change?
    Michael sweet Your claim of deviding R&D money by watts currently generated is obviously crank To not do so is obviously "crank". The subsides listed (a small part of the total subsidies) are annual. So they need to be divided by the energy produced. If you don't mormalsie the figures it is totally misleading. Its like sayoing SA produces more CO2 than Australia. So waht? It's meaningless. Just like trying to compare the annual subsides for wind and nuclear when wind generates about 1% of energy and nuclear about 20% (or what ever it is). It is pure spin. Not objective. Not reliable. Clearly "crank". Wind farm owners need to earn around $110/MWh to be profitable in Australia. It obviously varies from site to site. On top of this wind requires enhancement to the grid (not just more transmission lines) that cost around $15/MWh. Also, there additional costs for the fossil fuel plants that have to back up for wind power. The LCOE for New coal plants is around $50/MWh and much lower for existing plants. Put it all together and the cost of wind power is in the order of 2 to 2.5 times the cost of new coal power and much more than existing coal power. The gap is closed by mandating that wind power muct be bought by the distributors when it is available. That forces the electricity retailers to buy expensive, hard to manage, wind energy instead of cheaper coal or gas energy. The regulations caus eth cost to be about 100% to 150% higher. That is the subsidy I am talking about. Similar schemes exist in UK, Europe, Canada and I understand in Texas too.
  35. What should we do about climate change?
    Peter Lang, you claim that wind is subsidized 100%. The only "subsidy" that I have heard of for the Texas wind farms was they wanted the transmission lines built. Can you provide a reference for your claim of 100% subsidy for these installations? I currently pay $8/month for a nuclear reactor that has not been approved for construction and, IF approved, will not provide electricity for 10 years. Wind is installed by investors with their own money. Who is getting the bigger subsidy? Your shrill claims with little documentation are unconvincing. The more of your posts I read the less I am inclined to listen to what you say. I am starting to lean against nuclear if this is the best argument that can be put forth. Your claim of deviding R&D money by watts currently generated is obviously crank-- an established technology like nuclear should have much less R&D by the government than a new technology just getting started. Nuclear and coal profits should support 100% of their R&D. Where are the thorium reactors you support operating so that I can check the costs? Comparing nuclear waste safety to wind is laughable. You have still ignored my question about nuclear power stations in Afganistan, Zimbabwe and Nigeria. Do you think those countries can operate reactors safely? How can we use nuclear to power the whole world if many countries cannot operate reactors safely? What fraction of countries can currently operate reactors safely? If you cannot answer these questions you do not have a valid proposal.
  36. Climate change from 40 million years ago shows climate sensitivity to CO2
    #11 Thank you for your reply and your patience. No, I do not believe "that we can keep doing that without it having *any* negative impacts on our climate? " I have not said it would not have negative impacts on our climate.I have not said anything yet. "I'm still … collating, actually" :-)
  37. Climate change from 40 million years ago shows climate sensitivity to CO2
    #9 You said, "You are not listening." Yes I am :-) You said, " Fossil fuels accumulated over millions of years." I know this. You said, "fossil fuel burning during the past 150 years (and half of that within the past 60)." I know this. My point is ALL of the history of the planet must be factored into the discussion otherwise we just might be missing an important element. Its called lateral thinking. :-) You must think outside the square, otherwise you might miss something :-)
  38. Climate change from 40 million years ago shows climate sensitivity to CO2
    Just a side note. This paper is associated with a perspectives article written in the same issue by Paul N. Pearson from the School of Earth and Ocean Sciences, Cardiff University. In it he writes "Maximum levels in the MECO reached 4000 ppmv or higher—similar, perhaps, to a future anthropogenic greenhouse maximum." I've never seen any suggestion that CO2 levels are heading towards this level. Presently were creeping towards 400ppmv. Is this pure alarmism? If so what's it doing in the pages of Science magazine?
  39. Climate change from 40 million years ago shows climate sensitivity to CO2
    Sorry, I meant around 7 million years, not 70 million!
  40. Climate change from 40 million years ago shows climate sensitivity to CO2
    miekol, during much of the pre-Quaternary Era, the planet was subjected to massive levels of long-term (hundreds of millions of years) volcanism-as Pangaea slowly broke up & the continents moved into the positions we recognize today. This volcanism led to a *very* slow build up of CO2-to levels that were about 10 times higher than they are today-& this gave the planet *average* global temperatures of around 22 to 24 degrees Celsius (or around 6 to 8 degrees warmer than at any point in the Holocene). The CO2 was locked up again, over *tens of millions of years*, by the extensive plant-life that existed during the Carboniferous Era (during this time, most complex forms of animal life still spent the bulk of their time in the water). During the Carboniferous Era, temperatures also fell to levels more closely approximating our own. For at least the last 70 million years, though, levels of CO2 have remained locked between around 200ppm & 280ppm, which is testament to how slowly CO2 levels build up in the atmosphere due to volcanic influences. In the last 200 years or so, though, humans have been digging up these ancient reservoirs of prehistoric carbon & burning them-releasing their stored CO2 back into the atmosphere. Do you *really* believe, Miekol, that we can keep doing that without it having *any* negative impacts on our climate?
  41. Climate change from 40 million years ago shows climate sensitivity to CO2
    Having read the paper I've got the usual questions. 1)Where do they get the 2-3 times increase in CO2? In my mind going from 600-1600 to 6400-15000 is an increase by a factor of ~10? Just to clarify #1 and #2 in case they haven't been able to read the paper John has quoted the paper accurately. The authors say a factor of 2-3 but like Mike and KR I'm confused. This seems like such simple maths there must be an easy explanation. 2) I see no accounting for polar amplification in this work. There presently exists a theory that says temp will increase greater at the poles. I think ATM the arctic is believed to be warming at twice the rate as the global average. The paper actually says a "high latitude climate sensitivity". John are you assuming a global climate sensitivity in your write up here? I imagine if you were to take this papers estimate of "high latitude climate sensitivity" as accurate you would probably have to reduce the number if you were to try to estimate a global climate sensitivity from this work.
  42. Climate change from 40 million years ago shows climate sensitivity to CO2
    #9: "The fossil fuels that was once living organisms had to get their CO2 from the atmosphere," You are not listening. Fossil fuels accumulated over millions of years; fossil fuel burning during the past 150 years (and half of that within the past 60). "What about the other 4,520,000,000 years?" We live here, now. Comparing the distant past doesn't add to the discussion. Use the SkS Search if you're curious.
  43. Climate change from 40 million years ago shows climate sensitivity to CO2
    "Vast amounts of carbon were injected into the atmosphere during the Middle Eocene - where did it all come from?" The Eocene was intensely volcanic, including: The most powerful single eruption of this series took place 54.0 million years ago (Ma) and ejected ca. 1,200 km3 of ash material which makes it one of the largest eruptions in geological history. --Egger and Bruckl 2006 Zachos et al 2008 did a nice job of summarizing the climatic impacts.
  44. Climate change from 40 million years ago shows climate sensitivity to CO2
    #7: My point exactly. The fossil fuels that was once living organisms had to get their CO2 from the atmosphere, so early on the atmosphere must have been loaded with CO2. Like I said, its a closed system. Re:How do human CO2 emissions compare to natural CO2 emissions?....quote "atmospheric CO2 is at its highest level in 15 to 20 million years." What about the other 4,520,000,000 years?
  45. What should we do about climate change?
    JMurphy @347 From David Mackay, Plan C, page 2: Total electricity generation = 125 GW Nuclear generation = 70 GW "The electricity comes from the following sources. (The numbers given here are average outputs, not capacities.) Wind: 30GW; tide: 8GW; waste-to-energy: 2.5GW; “clean coal” and biomass co-firing: 3.2GW; nuclear: 70GW; concentrating solar power in deserts: 10GW. (That’s a total of about 125GW of electricity.)" 70 GW / 125 GW = 56%
  46. Climate change from 40 million years ago shows climate sensitivity to CO2
    Re 5 & 6 The correct thread might be here Some comments (incurring the wrath of the moderator) though, 1. Climate change may result in loss of biodiversity and the extent of loss is likely related to the rate of change 2. Wouldn't a warming world preferentially favour non-homeostatic organisms (e.g. bacteria and viruses over humans) ? 3. I was under the impression that for the marine ecosystems cold water played a vital role due to its increased O2 content.
  47. Climate change from 40 million years ago shows climate sensitivity to CO2
    #4: "all the CO2 that's here has always been here. Its just moved around a bit" Over-generalizing a wee bit? You would do well to read up on what is called the Carbon Cycle and how the climate changed in the past in the past. The quick answer? It is clear that all that CO2 has not always been in the atmosphere. A lot that spent millions of years as fossil fuels was dumped into the atmosphere in a very short period of time.
  48. What should we do about climate change?
    CB Dunkerson @346 "The simple reality is that countries all over the world are going forward with major wind and solar developments." They are being massively subsidised. 100% to 150% for wind power and in the order of 1000% for solar. Don't you read anything I post, or do you simply ignore what doesn't fit with your ideological beliefs? Why don't you advocate the same treatment for nuclear if you are genuinely more concerned about cutting CO2 emissions than about your ideological beliefs? "This inherently belies all arguments that they have no significant contribution to make." What do you mean by "significant"? Put some figures on it and put it in context as to how much CO2 emissions they can avoid compared with what we need to avoid, and the cost of avoidance compared with the cost of avoidance using nuclear. If you simply use adjectives and don't quantify any of your statements, then we cannot hold an intelligent discussion. - Did you mention that previously? a few times? :) There are many places where they are already making a significant contribution and that is set to become a worldwide reality in the next couple of decades." What do you mean by "significant"? Do you believe that renewables can/will cut emissions more than nuclear and at less cost? If so why. Layout your arguments, your figures, and authoritative sources. If Greenpeace and the like is your source, we can't have an intelligent conversation!!! The point is that you are the extremist. You want to block nuclear. I don't want to block renewables, I just want the least cost solution. Not a solution where one technology is blocked because of ideological beliefs. I say let's have a level playing field. If we do then I expect nuclear will be the dominant supplier of electricity and non-hydro renewables will have a small role. I presented the case as to why. Here is one of them (built on others that are cited in the document). Emissions cuts realities This shows just how impossiblly costly it would be for renewables to provide a predominant proportion of our electricity supply: Zero carbon Australia – Stationary energy plan - Critique
  49. What should we do about climate change?
    HI scaddenp, @5 (or perhaps #346 of numbers are fixed) We do? We ban nuclear weapons but as far as I know, no banning nuclear power. Last time I heard a government minister on the subject, nuclear was off table on economic grounds. So far we generate 70%+ electricity from renewables with plenty of remaining capacity for wind (no subsidies for power generation here) and some for geothermal. Replacing our transport fuels are another story however. I would guess NZ to be reasonably unique though (perhaps like Iceland) with small population and abundant renewables including lots of wind. About 50% of our CO2e is farm-related, mostly methane. I agree with all you say here - for New Zealand. But does that apply for your West Island (i.e. Australia for foreigners)? We have very little additional, viable hydro capacity (we could develop some pumped hydro and I gave a link to an example in a previous post) We have some limited wind resource mainly along the southern coast of Australia. However, this is unreliable and can go for days at a time without generating power (across all the NEM's wind farms spread over 1200km east-west by 800km north-south). The National Electricity Market draws about 600 GWh per day, so the amount of energy storage that would be required to make wind power dispatchable would be enormous. We do not have any volcanic areas like New Zealand, Iceland and other places located on the ring of fire and mid Atlantc ridge. Hot Dry Rock and Hot Fractured Rock geothermal is another unproven technology that suffers from similar limitations to solar - i.e a diffuse source of energy. Carbon Capture and Storage (CCS) is a pipe dream propogated by the coal mining industry to delay action for as long as possible. It will sequester some CO2 but the contribution will be insignificant and at huge cost. Wind power, when backed up by fossil fuels as would be the case in Australia, displaces negligible amounts of CO2 emissions (so I understand, I can be corrected on this if someone has access to studies based on measurement data). Much less than the wind industry claims. Wind power has not closed down fossil fuel power stations anywhere. So why would it in Australia? Solar thermal. The technology does not exist to enable it to provide baseload power. The costs for what it can provide are huge. See "Zero Carbon Australia - Stationary Energy Plan - Critique" Therefore, I suggest: 1. Australia's only realistic option for cutting emissions massively, over the long term, with a sustainable trend of reducing emissions by 50% or more by 2050, is to go nuclear in a big way. I agree there will be some renewables and so there should. But we need to unblock the log jam that is prohibiting nuclear and has been for the past 40 years. 2. Allow whatever technology is best able to meet the requirement at the time. Do not prohibit any. Do not stack the cards for or against any technology. Do not provide massive subsidies for renewables, coal, gas, CCS while providing none for nuclear (as we do in Australia). Do not mandate renewables. If we want to mandate anything it should be "clean energy" no "renewable energy". Mandating "Renewable energy" as we do now is a demonstration of policy based on ideology. 3. New Zealand doesn't need nuclear. You mentioned it was not economically viable. That is the case in Australia too, at the moment and based on the assumption of a regulatory regime as applied in the other western democracies. We, and I expect NZ, are looking at the cost of nculear under a regulatory regime which makes them uneconomic. I argue we have the option of high cost nuclear or low cost nuclear. High cost nuclear is nuclear in the USA, Canada, UK, EU. Low cost nuclear is in Russia, China, India, Korea. The plants all meet the IAEA requirements. We do not need high cost nuclear. There is little difference in the safety (if any) and all are far safer than what we have now, and accept nbow as sufficient. So any move to nuclear of any type will have a major improvement in health and safety and cut CO2 emissions. So we should go for least cost nuclear. 4. There are many advantages of going least cost, as I've said in previous posts. Low cost electricity will displace fossil fuels for heat and transport faster then if the cost is higher. I gave the comparison of France and Germany to demonstrate this. Also we need to develop low cost clean low emissions electricity in the west so it will be chosen in preference to fossil fuel generators in the developing nations. That is where the really big emissions cuts (or avoidance) will have to be achieved. I provided a post with much more detail a few pages back. 5. Stop the blkocks. Stop the ideologically based policies. Stop the extremesism (only renewables).
  50. Climate change from 40 million years ago shows climate sensitivity to CO2
    Earth's climate will have changed many times over its 4.54 billion years http://en.wikipedia.org/wiki/Age_of_the_Earth Since the Earth and its atmosphere is a closed system all the CO2 that's here has always been here. Its just moved around a bit :-) So what? So what nothing! Its simply my layman observation. Perhaps someone else can add to it.

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