Arguments
Recent Comments
Prev 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 Next
Comments 79601 to 79650:
-
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.
-
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.
-
Camburn at 13:53 PM on 12 July 2011The Medieval Warm(ish) Period In Pictures
muoncounter: I dn't have access to the full paper, Kirkbride and Dugmore. Note tho, that the glaciers did not peak at the same approx time. With that in mind, remember how small Iceland is. I will also point out that the proxy data from the Sargosa Sea presented in my link does not match the reanalysis from the Mann paper ref fig 1. -
muoncounter at 13:53 PM on 12 July 2011The Medieval Warm(ish) Period In Pictures
Camburn#28: "a paper that has been cited 70 times about temperatures during the MWP" Good one. From 1999, the primary evidence presented for MWP temperatures dates from 1966: Graph is modified from Keigwin, L. D., 1966, The Little Ice Age and Medieval Warming Period in the Sargasso Sea: Science, v. 274, p. 1504 - 1508. Nothing much has changed in dating technology since the '60s. Or at least what little I remember of the '60s.Moderator Response: [muoncounter] Correction: Keigwin's Sargasso Sea paper was published in 1996. The referenced source (Bluemle, Global warming: a geological perspective, which appears in NDGS Newsletter, vol. 26 no. 2) misprints the date of Keigwin as 1966 in their Figure 4 caption. -
RW1 at 13:44 PM on 12 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
scaddenp (RE: 18), "Um, I think "back radiation" is radiation emitted from the atmosphere that strikes the surface. I cant see how "last originated from surface emitted" can make any kind of sense. It's a key distinction because the amount that last originated from the surface is what is actually determining the net surface energy flux, which is what ultimately is determining the surface temperature. A lot of the downward emitted LW is 'forward radiation' that last originated from the Sun, yet to reach the surface. Also, the kinetic energy (latent heat and thermals) moved from the surface into the atmosphere is in addition to the radiative flux at the surface, so any amount from it radiated back to the surface also did not last originate from surface emitted of 396 W/M^2, which is the just net energy flux at the surface (in the steady-state at least). -
muoncounter at 13:41 PM on 12 July 2011The Medieval Warm(ish) Period In Pictures
Camburn#27: "during the MWP the precip was extensively higher than present. That would cause the advancement of glaceriers even if the temperature was warmer." High precipitation plus warm temperatures = glacial advance? Not what Kirkbride and Dugmore 2008 found in Iceland: medieval glacier advances between the 9th and 13th centuries are firmly identified for the first time in Iceland. This challenges the view of a prolonged Medieval Warm Period and supports fragmentary historical data that indicate significant medieval episodes of cooler and wetter conditions in Iceland. -- emphasis added Koch 2008 is also a good short summary on this question: an advance of Llewellyn Glacier, which drains the northeast sector of the Juneau Icefield, at the time of the Medieval Warm Period, cannot be reconciled with temperatures similar to those of today. This evidence suggests that temperatures were significantly lower than at present during the Medieval Warm Period, calling into question the existence of prolonged warmth at that time. We conclude that the Medieval Warm Period is at best an ill-defined term that encompasses a number of possibly unrelated climate anomalies. -- emphasis added -
Camburn at 13:41 PM on 12 July 2011The Medieval Warm(ish) Period In Pictures
DB: Koch etal talks about the increased precipitation in the Western Conus. Here is a paper that has been cited 70 times about temperatures during the MWP: Global Warming: A Geological Perspective -
Camburn at 13:16 PM on 12 July 2011The Medieval Warm(ish) Period In Pictures
DB: The reason for the advancement of the glaciers is not certain. There are proxies from NA that show during the MWP the precip was extensively higher than present. That would cause the advancement of glaceriers even if the temperature was warmer.Response:[DB] Citations please. Unsupported claims carry little weight.
Precipitation increases do not necessarily translate into glacier advances. The mass balance between increased depositions in the accumulation zone have to outweigh losses in the ablation zone for glaciers to advance. Warming typically increases the size of the ablation zone and decreases that of the accumulation zone resulting in glaciers pulling back from their terminal moraines.
-
Rob Honeycutt at 12:58 PM on 12 July 2011The Medieval Warm(ish) Period In Pictures
Eric... You might check out the first diagram in the article here. It seems that, for one, almost the entire central Eurasia region was actually cooler. I believe this is the point. There are clearly areas around the planet that show a MWP but the warming is heterogeneous in both time and place, and many areas of the planet were actually cooler during the MWP. This is completely different than today where we have extremely accurate measurements of the homogeneous warming. Call it a braided hockey stick with a very straight blade.Response:[DB] Interested parties may see also Koch and Clague 2011 wherein they show that that several glaciers in western North America and elsewhere in the world advanced during Medieval time and that some of these glaciers achieved extents similar to those at the peak of the Little Ice Age, a very cold period many hundreds of years later.
More discussion on this here.
-
Alec Cowan at 12:48 PM on 12 July 2011A Detailed Look at Renewable Baseload Energy
@267 Tom, I only have read what I supposed a faithful quotation in #264. In the sentence "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)." the phrase between parenthesis is factually wrong unless that land is a small spot that changes location by the minute -though I don't understand why third person singular if 20% and 80% are striking the same SM so 20% is not the subject- In the best case, it is a sloppy way to say it. I have at least the excuse of hardly speaking English -in spite of me using my real name here what seems to suppose some kind of linguistic obligation-. The term capacity is not really a problem, though it suggest a technological limit. I don't need to be "sold" solar energy. But I wasn't born yesterday. Free energy like solar or petroleum has the cost of knowing where to find it -solar is easy about that- and later the cost of making it available where and when you need it. I think that many people is needing lessons of economy, not ecology or physics, so they can land safely at last. If the topic was feasibility of solar energy, of course it is. What surface is needed? Just within the same order of magnitude of paved roads and urban sprawl in the United States. -
heystoopid at 12:30 PM on 12 July 2011SkS Weekly Digest #6
To whom it may concern, there appears to be a mixed up link in News bites thus:- "Millions of African Climate Refugees Desperate for Food, Water" currently links to Science Daily story ;'Fire to Become Increasingly Important Driver of Atmospheric Change in Warming World' I believe the correct link to be:- http://www.ens-newswire.com/ens/jul2011/2011-07-06-01.html -
Eric the Red at 12:26 PM on 12 July 2011The Medieval Warm(ish) Period In Pictures
Do you have any references showing otherwise? -
Eric the Red at 12:24 PM on 12 July 2011The Medieval Warm(ish) Period In Pictures
Especially the global temps from Lohle. -
Eric the Red at 12:22 PM on 12 July 2011The Medieval Warm(ish) Period In Pictures
Yes, Notive how all the proxies show the MWP as being warmer than today?Response:[DB] Factually incorrect. See Martín-Chivelet et al.
-
scaddenp at 11:51 AM on 12 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
Um, I think "back radiation" is radiation emitted from the atmosphere that strikes the surface. I cant see how "last originated from surface emitted" can make any kind of sense. -
scaddenp at 11:40 AM on 12 July 2011The 2nd law of thermodynamics and the greenhouse effect
Rosco - this is basic version. This argument has been done to death at in here. I note some confusion on Trenberth. I suggest you might like to get your head around some basics at Science of Doom (and the many other articles there). In short, the physics is more subtle than you think it is. -
RW1 at 11:30 AM on 12 July 2011Trenberth on Tracking Earth’s energy: A key to climate variability and change
Rosco (RE: 16), "I know they provide 333 W/sq metre "back radiation" but where do these joules come from to heat the atmosphere to the level where it radiates more than the incoming solar radiation?" If you read the tables in the paper, it's not really 'back radiation' but downward LW radiation received at the surface. Why he refers to this as 'back radiation' I don't know. The fundamental problem is downward LW at the surface has three potential sources: Some of it last originated from surface emitted LW, some of it last originated from the Sun absorbed by the atmosphere yet to reach the surface, and some of it last originated from the kinetic energy moved from the surface into the atmosphere while also radiates in the LW infrared. The term 'back radiation' generally implies downward emitted LW that last originated from surface emitted. The diagram makes it look like of the 396 W/m^2 emitted at the surface, 333 W/m^2 are coming back from the atmosphere, which is why it's confusing.
Prev 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 Next
