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Dikran Marsupial at 00:45 AM on 13 July 2011What we know and what we don't know
Eric the Red an exponential with a low rate constant can look "fairly linear", but it is still exponential. If you can show me an anlysis that robustly demonstrates that it is linear (rather than there just isn;'t enough data over shuch a short time span to distinguish between linear and exponential with statistical significance) then I am happy to stand corrected. The rise in CO2 is unaffected by our expectations, it is affected by our actions. As Niels Bhor said "Prediction is very difficult, especially about the future" - in the 70s they though we would all be flying around in our hovercars and would have a domestic robot doing our chores by now, but it hasnt happened. IMHO it is extremely rash to decide the action we should take now on the basis of what technological solutions the future may offer. There is an appreciable probability that such solutions will not be made available, or if they are they will be available too late. The advantage of predictions based on a continuation of what has gone before is that we know it is plausible a-priori. -
Eric the Red at 00:43 AM on 13 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
Ken, Nice post between the two theories. There may be other explanations for where the heat went, or why the heat has not reached the surface, which may be revealed when the data materializes. However, it does come down to two basic interpretations: either the heat is there, and we are just not measuing it (Trenberth), or the heat is not (Hansen). -
KR at 00:36 AM on 13 July 2011A Detailed Look at Renewable Baseload Energy
In my previous comment I am referring to pre-conversion energy available at tropical sites. Equations 1 and 2 yield the same numbers (with LAGI's figures being rather conservative), and hence LAGI is properly doing their math. -
Eric the Red at 00:35 AM on 13 July 2011What we know and what we don't know
Dikran, The CO2 rise was only exponential when you start from preindustrial levels. The rise has been fairly linear since 1975. Change is the only constant in our civilization, and no one could foresee the changes today 90 years ago, and we cannot foresee the changes 90 years from now. I do not think many people expect a contiued rise to 550 ppm by 2100. I do not think the point of this article to claim that we do not know anything at all, but rather what is certain, and what is uncertain. Nor do I think this article advocated not taking any action. -
KR at 00:34 AM on 13 July 2011A Detailed Look at Renewable Baseload Energy
BBD - To be as clear as possible: Power over the course of the year can be calculated in two different ways. (1) Daily average power/m^2 * number of hours per year, or 200 * 24 * 365. (2) Peak power/m^2 * effective number of hours peak power is available, or 1000 * 2000. You keep calculating it as: Daily average power/m^2 * effective number of hours peak power is available This is a fundamental math flaw, mixing the two equations. -
KR at 00:26 AM on 13 July 2011A Detailed Look at Renewable Baseload Energy
BBD - And... you repeat the error, by stating "200W/m2 x 2000 = 400kWh per m2" It's not 200W * 2000 hours, but 200W * 24 hours * 365 days. Or, 1000W * 2000 hours/year of available time for collection. 200W is daily per/hour average, while 1000W on the other hand is peak power that is then scaled by the hours that power is available (2000/year, or 5.5 hours a day, more, actually, tapered for morning/evening). Apples and oranges, BBD - you are taking a 24 hour daily average and then scaling again by a fraction of a day. This is an error. I simply don't know how to put that any more clearly, BBD. 200W daily average is already scaled by hourly availability - yet you scale it again! LAGI then (properly) applies a 20% conversion efficiency. 30% is possible for CSP, minus additional plant footprint - not unreasonable. -
BBD at 00:06 AM on 13 July 2011A Detailed Look at Renewable Baseload Energy
KR Yes! You've got it:LAGI figures of 1 KW/m^2 * 2000 hours = 2000 kWh/m^2/year before conversion efficiency applied. MacKay figures of Honolulu, HI, 248 W/h/m^2 daily average * 24 hours * 365 = 2172 kWh/m^2/year before conversion efficiency applied. No disagreement once scaling factors are accounted for.
LAGI has used a reasonable estimate for average raw energy density of 200W/m2. It's properly conservative compared to those we have for SA (220W/m2) and Honolulu (248W/m2). It then takes this estimate, and treats it as 'capacity' - without a plant conversion efficiency factor - and uses it to get its footprint estimate. In LAGI:average raw energy density = plant output
LAGI does this:average raw energy density = average output
200W/m2 x 2000 = 400kWh per m2 Instead of this:average raw energy density x plant conversion efficiency = average output
200 x 15%* = 30W/m2 30W/m2 x 2000 = 60kWh per m2 That's why it is wrong. *This is an example only. Put in your preferred CEF, but remember, anything above 20% is getting fanciful. -
Dikran Marsupial at 00:05 AM on 13 July 2011What we know and what we don't know
Eric the Red We do know something very important about what lies in the future for CO2 emissions, which is that it is almost entirely in or own hands; if we want atmospheric CO2 to fall, we can make it happen; if we want it to stabilise we can make that happen too; if we are stupid enough to continue the exponential rise all we have to do is carry on with "business as usual". As regards climate sensitivity etc., the fact that we don't know anything for certain doesn't mean we don't know anything; not all theories that have yet to be refuted have equal support from the observations. Some theories are more plausible than others, and there is a well understood mechanism for determining the best course of action under uncertainty - namely statistical decision theory. So lack of certainty is not a good reason for not taking any action and waiting to see what will happen. -
Rob Honeycutt at 00:03 AM on 13 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
Ken... "we could not expect Asian aerosols to disappear anytime soon." You might be surprised on that one. The rate of change on almost every level in society in China is very rapid. The clean air act in the US had a pretty rapid affect on air pollution here. There is no reason to believe that China's responses to air pollution will be any slower. -
Eric the Red at 23:49 PM on 12 July 2011What we know and what we don't know
Very good analysis of what we do know, and the contentions that a majority of scientists believe that humans have contributed. The unknowns need to be assessed for what they are. We do not know what lies in the future for CO2 emission, nor do we know how much warming will be caused. Other contributors and feedbakcs are still being assessed. Lastly, we can only speculate on future effects based on observed effects. -
KR at 23:45 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
BBD - Comparisons, converting both 'apples' and 'oranges' into juice: LAGI figures of 1 KW/m^2 * 2000 hours = 2000 kWh/m^2/year before conversion efficiency applied. MacKay figures of Honolulu, HI, 248 W/h/m^2 daily average * 24 hours * 365 = 2172 kWh/m^2/year before conversion efficiency applied. No disagreement once scaling factors are accounted for. -
KR at 23:36 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
BBD - Reposting sometimes occurs when a page is refreshed; that's happened to me a number of times. -
BBD at 23:35 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
Moderator Dikram Marsupial I do not understand why the deleted comment has re-appeared. If I have somehow re-sent it I did so in errorModerator Response: [Dikran Marsupial] No problem, I have deleted it. I suspect KR is right, I've done the same thing myself more than once! -
KR at 23:35 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
BBD - MacKay does not indicate in that chart whether that is raw power or power over the course of the day. Looking at raw insolation for Africa, for example, extracting 400 kWh/m^2 over the course of the year represents about 20% of available power.
MacKay's chart looks like daily average insolation (including night), whereas the LAGI figures are raw insolation times hours that is available - Apples and oranges, BBD.
You state:
"LAGI says:
We can figure a capacity of .2KW per SM of land (an efficiency of 20% of the 1000 watts that strikes the surface in each SM of land). What it means is that average raw energy density at the surface is 200W/m2.
The choice of words is fabulously confusing. One might even suspect deliberately so."
What LAGI actually states in that figure is: "Areas are calculated based on an assumption of 20% operating efficiency of collection devices and a 2000 hour per year natural solar input of 1000 watts per square meter striking the surface."
I found that quite clear - you have (mis)stated the figure, which shows your confusion on the LAGI statement. Raw insolation is on the order of 1000 W/m^2, not 200 W/m^2, and taking (as you have repeatedly) an output value of 200 W/m^2 and then applying conversion efficiency again is an error.
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And now for some math from your South Africa example:
5.25 kWh/m^2 per day * 365 days is 1916 kWh/year available; extracting 20% of that would be 383 kWh/m^2 - both numbers right about what LAGI estimates. An average of 220 W/m^2 over the course of the day looks about right for an insolation peak of 1000 W/m^2.
You keep confusing averages over the course of the day with peak insolation * hours available, BBD, and then claiming calculations based on the latter are incorrect. I don't believe it's worth discussing this matter further with you until we can agree on a common vocabulary.
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Ken Lambert at 23:34 PM on 12 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
Michael Sweet #11 This is remarkable statement: "Here we see real skepticism at work in science. Hansen has proposed that aerosols reflect more heat into space. Trenberth proposes that the missing heat has been absorbed into the deep ocean. Hansen is skeptical of Trenberth's results and Trenberth is skeptical of Hansen. Both of them will marshall their data to determine which is more correct (it may be a combination of both effects). In the end the data will determine who is correct. This is an example of real climate scientists debating the data." Probably the two most prominent climate scientists on the planet disagree about whether or not the warming imbalance is 0.9W/sq.m or 0.59W/sq.m over the last 5-6 years when the imbalance must in theory be increasing due to increased CO2GHG in the atmosphere. Dr Trenberth says the missing heat 'is there but we just can't yet measure it in the oceans' and Dr Hansen says the heat 'is not there because extra aerosols have reflected it out to space'. This seems to be a fundamental difference in how the trajectory of warming might evolve - as we could not expect Asian aerosols to disappear anytime soon. Dr Trenberth wrote: "While the planetary imbalance at TOA is too small to measure directly from satellite, instruments are far more stable than they are absolutely accurate. Tracking relative changes in Earth’s energy by measuring solar radiation in and infrared radiation out to space, and thus changes in the net radiation, seems to be at hand." The CERES satellite data quoted in the Aug09 paper for 2000-05 were adjusted to an estimated imbalance of 0.9W/sq.m from an absolute value of about +6.4W/sq.m. The latest data shown in Fig 3 above shows an Rt value varying around the 1.0W/sq.m. How is this data 'adjusted' from the absolute value? I would also like to ask Dr Trenberth whether the ENSO-La Nina cycles are 'internal' redistributions of global heat already within the system or are external global forcings which should be added to the RF and climate response terms to determine an imbalance. The final issue I query is how Dr Trenberth's 'missing heat' gets into the deep oceans in a relatively short few years. viz. "The overturning may involve the ocean down to several kilometers and can take many centuries to complete a cycle". -
Humanracesurvival at 23:28 PM on 12 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
Re #28, part of the top soils are "rocks" which too react with thermal energy. Thermal stress weathering (sometimes called insolation weathering)results from expansion or contraction of rock, caused by temperature changes. Thermal stress weathering comprises two main types, thermal shock and thermal fatigue. Thermal stress weathering is an important mechanism in deserts, where there is a large diurnal temperature range, hot in the day and cold at night. The repeated heating and cooling exerts stress on the outer layers of rocks, which can cause their outer layers to peel off in thin sheets. Forest fires and range fires are also known to cause significant weathering of rocks and boulders exposed along the ground surface. Intense, localized heat can rapidly expand a boulder. Although temperature changes are the principal driver, moisture can enhance thermal expansion in rock too. Pedology -
BBD at 23:19 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
Tom [posturing deleted]Moderator Response: [Dikran Marsupial] Skeptical science is for calm rational discussion of scientific issues relating to climate change. Rhetoric is not appropriate; please everybody let's get back to a more moderate, impersonal tone. -
BBD at 23:17 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
Oh, don't mind me. Here's what the Energy Department of the Republic of South Africa says about average raw energy density at the surface:Most areas in South Africa average more than 2 500 hours of sunshine per year, and average solar-radiation levels range between 4.5 and 6.5kWh/m2 in one day. The southern African region, and in fact the whole of Africa, has sunshine all year round. The annual 24-hour global solar radiation average is about 220 W/m2 for South Africa, compared with about 150 W/m2 for parts of the USA, and about 100 W/m2 for Europe and the United Kingdom. This makes South Africa's local resource one of the highest in the world.
Any pennies dropped yet? -
Tom Curtis at 23:13 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
BBD @276, do you think it just might be possible that it sounds like they are trying to say something different from how you interpret it because they are trying to say something different from how you interpret it? Or do you hold it as a axiom that you cannot misinterpret what somebody else says? -
Tom Curtis at 23:05 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
Alec Cowan @274, LAGI do not assert that 1000 Watts strikes every square meter of land. You put that claim into their mouths. In other words, you verbaled them. Until you go to their site, and follow up the link in which they justify their claim, and show that they are claiming something ridiculous, you are accusing them of asserting falsehoods solely on the basis of your lazy interpretation. And I don't give a hoot what your views are on global warming or solar power, or anything, that is a nasty habit. My criticism of you has nothing to do with any disagreement I have with BBD. As is quite evident from his posts, he has not yet even caught on that LAGI make the claim that you are mistakenly rejecting. It does have everything to do with rejecting a style of criticism that insists on interpreting the views being discussed, not as they are understood by the author of that view, but by dressing that view up in a straight jacket of the critiques own devising, thus interpreting sensible claims as ridiculous. It is an argument style I strenuously dislike, because it is lazy, because it is dishonest, and because it makes actual debate impossible. -
Eric the Red at 23:03 PM on 12 July 2011The Medieval Warm(ish) Period In Pictures
Using the proxy data referenced by Albatross, Mann (2008) showed temperatures between 1000 and 1100 to be similar to 2000. The Moberg (2005) proxies (NH only) were highest in the 1000 - 1100 years. Loehle (2008) shows the highest global temperatures occurred ~900. Ljungqvist proxies show the highest NH temperatures centered around 1000. All these proxies show a distinct MWP, although the timing varies due to the proxies used. -
Jumper at 22:54 PM on 12 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
I was reading a thing by a denier and he seemed confused about energy in / out. I immediately thought of the quartz or glass tubes around kerosene heaters. The energy outflow is retarded and the catalytic metal sleeve becomes red hot; hotter than it would without the glass tube. Yet energy output is the same. (except for the catalysis itself!) The point is, even with much more retained heat, the net outflow will quickly reach equilibrium. I suppose I should have pointed that out to the denier. -
Jumper at 22:49 PM on 12 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
Interesting, Human. As a soil science person, I wondered about the energy difference between the top 10 meters of soil with, and without, groundwater. By my hypothesis, drought can mask the energy calculations. Unsure. Connolly says this dwarfed by oceans, if I read him correctly. -
BBD at 22:31 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
KRNo. LAGI, Tom, and myself have assumed 1 KW/m^2 raw energy intensity for a near equatorial site, which is then scaled by conversion efficiency and (quite importantly, and not done by LAGI) plant fill factor.
If you look at this set of values for average raw energy density at the surface range from 87W/m2 to 273W/m2. This is where I get my 200W/m2 raw energy average. I've been saying this over and over here. Perhaps now the penny will drop. Once more, for the record: 200W/m2 is a good estimate for average raw energy density at the surface for low latitude desert. So far, so good. But then LAGI causes much confusion by its use of the term 'capacity' (emphasis added):We can figure a capacity of .2KW per SM of land (an efficiency of 20% of the 1000 watts that strikes the surface in each SM of land). So now we know the capacity of each square meter and what our goal is. We have our capacity in KW so in order to figure out how much area we’ll need, we have to multiply it by the number of hours that we can expect each of those square meters of photovoltaic panel to be outputting the .2KW capacity (kilowatts x hours = kW•h).
LAGI does this:average raw energy density = average output
200W/m2 x 2000 = 400kWh per m2 Instead of this:average raw energy density x plant conversion efficiency = average output
200 x 15% = 30W/m2 30W/m2 x 2000 = 60kWh per m2 What I suggested at 271 is that you can see that LAGI is nonsense because it's entire calculation is based on solar plant with an average output of 200W/m2. It doesn't exist. Can you please, finally, just take a few minutes to think about this (eg #270 and #271). It beggars belief that something so obvious can be misunderstood for so long. -
Eric the Red at 22:28 PM on 12 July 20112010 - 2011: Earth's most extreme weather since 1816?
Albatross, Trapp has concluded that CAPE is the dominant factor in determing supercell formation. That theory is not shared by all. Others maintain that vertical shear is most important. What is agreed upon is that when both are high, severe thunderstorm formation, and possible tornadic activity are most likely. We disagree on the same point. Currently, I am leaning towards wind shear being most important, but have not ruled out CAPE being most important. I am basing this on current studies which show available moisture increasing throughout the summer months, but wind shear decreasing, and consequently, severe storms decreasing as the summer progresses. -
Alec Cowan at 22:25 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
It looks for me now that all three of you are here because you enjoy the swamp. Tom, you chose to voluntarily ignore BBD in a recently deleted comment. Don't use me to continue your feud with that person. I told you that I don't need to be sold "solar". I'm telling you I don't need to be lectured about solar either. The notion of 1000 Watts striking every square meter of land on a regular basis is dead wrong. Don't build up a list of "buts" to excuse the author. That he or she may have been carried away by legitimate enthusiasm and a sales pitch mood, I agree, but that doesn't change how the world works. BBD, now part of your mind has realized your gruesome arithmetical mistakes after a spree of sterile debate caused by that mistake. The chosen strategy is asking others a written admission of the straw in their eyes. You are moving now to efficiency in a effort to keep your preformatted conclusions and simultaneously avoid the apologies about the rafter that any level-headed grown-up would give. I'm telling you: Tell yourself whatever you want, but it shows! It shows, and it's written! -
KR at 22:09 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
In my previous comment I may have underestimated the fill factor at Waldpolenz Solar Park and the CSP plants; to the extent that I have done so more energy per land area is available. I've found it rather difficult to get the numbers for these. Conversion efficiency of 15 to perhaps 20% of collected raw energy is possible with current technology photovoltaics, while CSP is rated at 30%+ for high temperature arrangements. But it's easier to densely fill the land with collectors for PV, so this CSP advantage may cancel out. -
Humanracesurvival at 21:56 PM on 12 July 2011Irregular Climate Episode 21
Video: More than 8 billion cubic metres of natural gas are lost in the US each year -
Alec Cowan at 21:46 PM on 12 July 2011The Medieval Warm(ish) Period In Pictures
@35 Wow, wow! It looked a bad copy of [- snip unnecessary disease references; some people around here actually have those problems -] Do I need to recite a creed to get clearance? It's difficult to me; I'm Postheist. But called to do it, and as my only objection is using the verb "believe", I say: I believe in an ongoing AGW that is endangering the biosphere in such a degree that an obstinate keeping of those trends in the eighties during a couple of centuries will provoke events of dire consequences in a global scale. That said, if you can avoid spotting a denier in disguise in every criticism you'll hear from me, you may explain for me what is the "it" in your "I think if you're wanting someone to rail against it should be Hubert Lamb?". I found that in English people tend to get cocky before talking clear. Additionally, as you should have realised from the start, I'm not saying that the so-called MWP wasn't just a regional development. I'm saying that Figure 1 can be misinterpreted as showing a cooling average because it's contrasted against a warm period. That is not bona fide, the same way that is not bonafide your innuendos of me being a climatard just because I don't agree automatically with what is shown here. Your belligerent summoning for me to have all the backing information of Mann, Zhang, Rutherford et al read and analyzed together with a search for alternative renders for that period, in less of 24 hours, in a working day, is not bonafide too.Moderator Response: [muoncounter] The only thing you need do to get 'clearance' (whatever that means), is keep your comments rational, on topic and supported by evidence. No one really cares about your 'creed' or your interpretation of English speech patterns. -
Humanracesurvival at 21:29 PM on 12 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
I meant to write Pedosphere -
Humanracesurvival at 21:15 PM on 12 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
"the exchange of energy between the atmosphere and ocean is ubiquitous, so that heat once sequestered can resurface at a later time to affect weather and climate on a global scale" I'm missing a more in depth part about the atmosphere/hydrosphere interconnection - how the changing weathering process affects land mass and flux of heat content therein. "although some heat has gone into the record breaking loss of Arctic sea ice, and some has undoubtedly contributed to unprecedented melting of Greenland and Antarctica, these anomalies are unable to account for much of the measured TOA energy (Fig. 4). This gives rise to the concept of “missing energy” " Could this indicate an uptake of permafrost melt and other such processes, increase of weathering-erosion of the pedoshere? In the sense that decomposition of organic materials, the soil permafrost environment transition into a more fluid "unstable" state, could account for the missing heat? -
KR at 21:09 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
BBD - Aha, a light dawns (so to speak). "Here's what LAGI does: - reasonably assumes 200W/m2 raw energy density - multiplies 200W/m2 by the estimate of 2000 hours p/a of direct sunlight: 200W/m2 x 2000 = 400kWh per m2 - and on this assumption estimates: - 500,000 km2 = 23TW Plant conversion efficiency is not calculated." (emphasis added) No. LAGI, Tom, and myself have assumed 1 KW/m^2 raw energy intensity for a near equatorial site, which is then scaled by conversion efficiency and (quite importantly, and not done by LAGI) plant fill factor. 1KW * 0.2 efficiency * 2000 p/a = 400kWh/m^2 including plant efficiency. You appear to have applied the LAGI 20% efficiency twice, BBD, and are starting from a raw power a factor of five too low. Did you read Tom's post here? Showing insolation for New Mexico, with irradiance of ~1 KW/m^2? Where are you getting 200 W/m^2 for tropic raw power? You are incorrect. [Waldpolenz Solar Park in Germany, incidentally, has a fill factor (collection to plant areas) of ~30%, a conversion efficiency of ~12%, so 30% is quite achievable with current tech for PV - scaling up LAGI's land estimates by 3.3 at most for PV. Most current CSP plants have lower fill factors, ~15%, although some have hit 30% (Solar Millennium, Ridgecrest CA, parabolic trough, appears to be at 30%). So scaling up LAGI's estimates by 3.3 is reasonable for a physically achievable power station. Downscaling raw power by 5, on the other hand, is not.] -
Eric (skeptic) at 21:07 PM on 12 July 2011Over the tipping point
#13, Artful Dodger, I answered that question in another thread /argument.php?p=2&t=113&&a=80#54888 and a link to a simple spreadsheet. There was general agreement that if we stopped now, the current level would fall half way back to preindustrial within 50 years.Moderator Response:(DB) Umm, no, there was not "general agreement"; please re-read the responses and look for mine and Sphaerica's comments (the guest post by Dr Franszen has discussion supporting Dodger's position on oceanic outgassing of CO2).
Edit:
[DB] The post I referenced is the Seawater Equilibria thread. The relevant discussion I alluded to starts at comment 30. Specific relevant comments are numbers 33, 41, 43, 45, 67, 78 and 81.
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Eric (skeptic) at 20:45 PM on 12 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
One thing I don't understand is short term variability in GAT, for example, in the first column here: http://vortex.nsstc.uah.edu/data/msu/t2lt/uahncdc.lt Looking at that first column, there is a clear AGW and clear ENSO response. But there is also a month-to-month variability that can be as much as 0.1 or 0.2 This variability even tracks down to the day timeframe although that is more unusual. My question is, is there an energy transfer with the ocean over such short time intervals, or is it just lost to space and regained later? -
BBD at 20:22 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
Since there seems to be something of a mental log-jam going on here, how about a different framing of the problem with LAGI: LAGI calculates: 200W/m2 x 2000 = 400kWh per m2 Average output capacity per square metre is given as: 200W/m2 What kind of solar plant delivers an average output capacity of 200W/m2? See it now? -
Rob Painting at 19:28 PM on 12 July 2011The Medieval Warm(ish) Period In Pictures
Camburn @ 32 - The Sargasso sea was warm in the MWP. See figure 2 above. Mike Mann is well aware I'm sure. -
BBD at 19:11 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
Tom You are not addressing #264. At #252, you said (and not for the first time - it is your entire argument):LAGI do not use a 200 Watt insolation value (which they give as 1000 W/m^2), and they do not omitting the panel conversion efficiency (which they give as 20%).
But that is exactly what LAGI does. It multiplies 200W/m2 by the estimate of 2000 hours p/a of direct sunlight: 200W/m2 x 2000 = 400kWh per m2 And on this assumption estimates: 500,000 km2 = 23TW Plant conversion efficiency is not calculated Instead of this:average raw energy density x plant conversion efficiency = average output
LAGI does this:average raw energy density = average output
200W/m2 x 2000 = 400kWh per m2 I show this, again, at #264. Please respond to this. Do not introduce any extraneous argument. Respond to this alone. Politely. You must: - show that it is incorrect or - admit that LAGI is in error # 264. -
Rob Painting at 19:04 PM on 12 July 2011The Medieval Warm(ish) Period In Pictures
Alec Cowan @ 13 & 19 - Okay so nothing constructive, I thought this might lead to some rational discussion - my bad. I think if you're wanting someone to rail against it should be Hubert Lamb? He's the one who started the MWP nonsense in the first place. -
Magnus W at 17:46 PM on 12 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
It would be very interesting to hear what Kevin have to say about the sulfur situation and possibilities of tracking the heat in the ocean with todays measurement systems... i.e. articles linked in comment 23 and 7. And I guess this also comes in to play: http://www.springerlink.com/content/akh241460p342708/ we estimate that up to one third of the late twentieth century warming could have been a consequence of natural variability. -
Dikran Marsupial at 17:25 PM on 12 July 2011CO2 has a short residence time
The adjustment time depends on the net difference between total uptake and total emissions. It is true that the uncertainty in the estimates of the magnitude of the individual environmental fluxes is large compared with anthropogenic emissions, we don't need to know the magnitudes of the individual fluxes to obtain a much more certain estimate of their differences. Assuming conservation of mass, then dC = E_a + E_n – U_n where dC is the change in atmospheric CO2, E_a is anthropogenic emissions, E_n is total environmental emissions and U_n is total environmental uptake. Rearranging we get dC - E_a = E_n - U_n We can measure dC accurately via the e.g. the Mauna Loa data and anthropogenic emissions are estimated accurately (as energy use is generally regulated and/or taxed so governments keep good records). As we have an equality, the uncertainty on the right hand side is the same as the uncertainty on the left hand side. So while we don't know the magnitudes of E_n or U_n with any great accuracy, we have a method of constraining the uncertainty on their difference using the uncertainty in the difference of dC and E_a. If you build a one box model of the carbon cycle (i.e. a first order linear differential equation) and calibrate it using the observations of dC and estimates of E_a over the course of the Mauna Loa record, you end up with a residenc time of about three/four years and an adjustment time of about 74 years, which is in good accord with the figures given by the IPCC. I'll post a more detailed explanation in the (hopefuuly) not too distant future. As to C14, this approach gives an estimate of residence time, not adjustment time. The adjustment time is a measure of how quickly CO2 is permanently removed from the atmosphere; residence time is a measure of how rapidly carbon is exchanged between the atmospheric and oceanic/terrestrial biosphere reservoirs. The vast majority of the C14 from nuclear tests has not been permanently taken out of the atmosphere, just replaced by carbon dioxide containing lighter isotopes of carbon due to the vast exchange fluxes. The C14 data thus is a measure of residence time. Essentially the IPCC figures are entirely in accord with the piblished litterature on tracer measuement. -
Tom Curtis at 16:21 PM on 12 July 2011Over the tipping point
Artful Dodger @13, currently the annual increase in atmospheric CO2 is still less than annual human CO2 emissions. Therefore natural sources are still a net sink of CO2, and where we to stop all CO2 emissions tomorrow, the CO2 concentration in the atmosphere would start to slowly decrease. It is true that evidence is showing the natural carbon cycle is becoming less efficient as a sink for anthropogenic CO2. Further, it is true that we may be approaching one of several potential tipping points that would turn natural sources into a net source of CO2. Indeed, warming currently in the pipeline due to thermal lag may even take us over such a tipping point. Consequently it is possible that natural processes could take us to 1200 ppm CO2 by 2200, but it is not likely. In the event that we stopped all emissions in the next 10 or even 20 years, it is more likely than not that CO2 concentrations would decrease. But the longer we delay, the more likely that natural mechanisms will double or even triple CO2 concentrations. -
Artful Dodger at 15:19 PM on 12 July 2011Over the tipping point
Adelady #5: A CO2-balancing scheme may have worked in a pre-350 ppm world. However, our present situation is far worse because there are now more sources of CO2 (soil aeration, deforestation, permafrost, methane clathrates, etc...) than those caused by human burning of fossil fuels. In other words, EVEN if human emissions when to zero NOW, the Earth is still probably headed to 1200 ppm CO2 within 200 years. Maybe 800 ppm by 2100. We are in a deep hole, but still digging. Have you seen the video where a cruise ship Captain tries to avoid crashing into a dock, but can't stop the momentum of the ship? Well, imagine you are a passenger on that ship, and the only means you have to avert the crash is to move the Ocean! Because that is the equivalent task for the Public in averting Climate Change... As we capture CO2, the world Ocean simply gives up its sink of dissolved CO2 to maintain gas pressure equilibrium between the ocean and atmosphere. This is why Climate Change is unstoppable for millennia. The only reasonable solution is restoring the biosphere, and letting time take it's course. Do we have the wisdom and courage to take this action? Or will the Captains of Industry pilot Human Civilization onto the rocks? Remember who took the lifeboat seats on the Titanic... -
Daniel Bailey at 14:41 PM on 12 July 2011The Medieval Warm(ish) Period In Pictures
But of course, since the dissemblers would have us believe the MWP was as warm or warmer than today, the Arctic must've been mostly melted then, too, right? But actual evidence shows that the waters now entering the Arctic Ocean from the Atlantic Ocean are the warmest they've been in the last 2,000 years. Yet another MWP "Silver Bullet" (an underwater hockey stick, no less). Time for another Coors Lite... -
scaddenp at 14:36 PM on 12 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
RW1 - Sorry, this is weird. It sounds like you are thinking of this as photons being little balls bouncing around with a "history" of where that have been. Instead, this is a series of energy balances reflecting all energy transfer processes. Its unphysical to try and track a photon "history". Perhaps it would be clearer if looked how each flow was determined. -
scaddenp at 14:29 PM on 12 July 2011The Medieval Warm(ish) Period In Pictures
muoncounter - this is however the dynamic for glaciers on west coast of NZ. In deep shaded valleys (and with high rockfall load, the increased precipitation from warmer Tasman sea overrides the warmer terminus. I think the same dynamics affect glaciers in southern South America. I'd say you need data from past behaviour of the glaciers concerned to interpret the changes. That said, I think Eric is onto a rich vein of denial memes (eg Loehle is good construction; proxies are show cooler than MWP even if instrument doesnt; I guess Mann 2009 is wrong because its by Mann? -
intrepid_wanders at 14:28 PM on 12 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
I am unsure where the question of the missing heat is, R. S. Knox, David H. Douglass 2010; (Recent energy balance of Earth International Journal of Geosciences, 2010) is quite sufficient for explanation of the complexity. -
Tom Curtis at 14:06 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
Alec Cowan @268, there is a difference between being abbreviated (or simplified) and being wrong. In the former case there are relevant qualifications or conditions which are omitted for simplicity or brevity of exposition, but which are reasonably evident from context, or explained in more detailed work elsewhere (which is preferably cited or linked, but often not). In the latter case, the statement is simply false or misleading in the context regardless of any unmentioned qualifications. The unstated qualifications in this case are that the irradiance figure is the clear sky, daylight direct normal irradiance. Here are clear sky irradiance figures for Albaquerque, New Mexico (35.11 degrees North) for June 22:
Note that with 2-axis tracking, solar irradiance of 1000 W/m^is achieved for 8 hours of the day, with the sun having an altitude of approximately 78 degrees at noon. Between the tropics this would be a reasonable annual average.
On December 22, with a solar altitude of 32 degrees at noon, the 2-axis tracking clear sky, daylight direct normal irradiance still averages 800 W/m^2 for eight hours of the day:
As it happens, LAGI do link to a source for their 1000 W/m^2 figure, but google docs won't open it for me so I cannot comment on it.
-
Camburn at 14:04 PM on 12 July 2011The Medieval Warm(ish) Period In Pictures
muoncounter: Woods hole was pretty excited about this, and to my knowledge, this temp study of the Sarasota Sea has never been disputed till now. I don't understand how Dr. Mann missed this. Woods Hole discussion of Sarasota Sea proxy data -
dhogaza at 13:58 PM on 12 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
A lot of the downward emitted LW is 'forward radiation' that last originated from the Sun, yet to reach the surface.
You need to quantify this, or, if you're too lazy, just point us to whatever denialist screed has raised the issue. Because hopefully they'll have quantified "a lot", and, of course (!), thereby prove that it's not coming from the GHG mechanism, proving some modern physics false, etc, etc ... -
RW1 at 13:54 PM on 12 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
I also dispute the way the diagram depicts 78 W/m^2 of the post albedo as being 'absorbed by the atmosphere' without ultimately getting the surface somehow. I certainly don't dispute that some of the post albedo is absorbed by the atmosphere (mostly clouds), but if any of this energy finds it's way radiated out to space without ever reaching the surface, it's trading off energy from the surface absorbed by clouds that would otherwise have be leaving the system at the TOA. Indirectly one way or another, the full post albedo has to get to the surface if COE is to be satisfied. The numbers don't work unless it does. Also, where is the return path of latent heat in the form of precipitation in the diagram? Surely, not all of it returns to the surface in the form of downward LW.Response:[DB] Please do not rehash the entirety of the 2nd Law thread. You were painstakingly corrected there, many times, by patient commentators.
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