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Comments 27601 to 27650:
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bozzza at 15:43 PM on 28 August 2015Tracking the 2C Limit - July 2015
Dear OPOF,
Can we please forget the fallacy of the wise mountain-climber always climbing the mountain?
As someone famous once said: "Not all metaphors bear close examination!"
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One Planet Only Forever at 14:08 PM on 28 August 2015Tracking the 2C Limit - July 2015
Digby Scorgie @20,
Let me try to explain why saying "the task is impossible" is not applicable to this issue.
The task is to raise awarness of the change of human activity that is required for humanity to have a good chance of developing a lasting constantly improving future for all humanity (which requires a robust diversity of other life on this planet).
The 2C target is an aspiration and not in the sense of making it to the summit of a mountain. Unlike mountain climbing where the wise climber will 'give up the ascent when conditions clearly are not in favour of success', this is a matter where it is essential to achieve the best possible result (which, by the way, a wise mountain climber will be able to do and the risk takers will not), because the consequences of giving up or taking the risk are truly unacceptable (there will be no 'next chance to reach the summit' and others in the fuure will suffer the consequences of the joy-ride of the thrill seeking risk-taker).
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Digby Scorgie at 13:41 PM on 28 August 2015Tracking the 2C Limit - July 2015
Dear Moderator, I thought the correct way to annotate the graph is relevant, but okay I'll go on to something that is:
I too would like to see some way of indicating the inherent lag in the system. However, I've seen estimates of 0.5 degrees already built in, not just 0.3 degrees. I've also seen comments to the effect that 2 degrees is now unavoidable. Uncertainties like this probably render the task impossible.
And before signing off, I'll quickly interpolate my defence (excuse?) regarding Celsius: I did say "a few decades" ago!
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scaddenp at 10:37 AM on 28 August 2015Here’s what happens when you try to replicate climate contrarian papers
Looking at the "many scientific contemporaries" this conjectures that it would be less than a dozen. However, one of them was Kepler. I dont think any contemporary would-be-Galileo has someone in the same order supporting them.
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Ed Wiebe at 01:25 AM on 28 August 2015Tracking the 2C Limit - July 2015
Digby, The only exception made to the space convention is for degrees, minutes, and seconds, °, ', " the symbols for the unit(s) of plane angle. °C is the the symbol for a specially defined SI derived unit "degree celsius". Yes, it's not an SI base unit but it is a clearly defined "derived unit". I agree that this detail is principally a style convention but it's a good one to follow. Number_space_unit.
It's very clearly laid out in this text from the Bureau International des Poids et Mesures (BIPM). http://www.bipm.org/en/publications/si-brochure/section5-3-3.html
See also http://www.bipm.org/metrology/thermometry/units.html#si-brochure.
It's also explained clearly in documents from NIST (National Institute of Standards and Technology) for those who prefer a USA centric reference.
[And don't get me started on the way people embed C for carbon in units of mass or concentration or what not. That's completely wrong and adds to confusion rather than clarifies.]Moderator Response:[PS] Fixed link. Please use the link button in the editor to create links.
And please, no more. Dont derail this thread with offtopic discussion.
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jja at 01:12 AM on 28 August 2015Tracking the 2C Limit - July 2015
We are waking up to the fact that the 2C limit is untenable for continuity of an integrated global modern society.
http://cleantechnica.com/2015/08/26/world-must-almost-completely-decarbonize-in-next-35-years-to-tackle-climate-change/Moderator Response:[PS] Fixed link. Please use the link button in the editor to create links
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knaugle at 00:43 AM on 28 August 2015New paper shows that renewables can supply 100% of all energy (not just electricity)
@Michael Sweet
My numbers for Nuclear power are accurate and for wind power are reasonable. For nuclear power, average capacity factor (including outage time) has hovered right at 90%.
As for wind power, I still think 25% is a reasonable estimate, though there are numbers out there that are all over the board:
http://www.eia.gov/todayinenergy/detail.cfm?id=22452
https://en.wikipedia.org/wiki/Wind_power_in_the_United_States
Also several sources of data from 2008 suggest Europe was struggling to meet even 20%. So as we add wind turbines, there is the liklihood that as less optimal locations are selected the current USA CF declines from the current values.
Moderator Response:[PS] Fixed link. Please use the link button in the editor to create links
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chapeaured at 00:37 AM on 28 August 2015Here’s what happens when you try to replicate climate contrarian papers
When you look closely at the surveys of the most qualified climate scientists — those actively doing research and publishing their results in peer reviewed journals — you find 97 to 97.5% who believe that the climate is warming and that man is a major cause and only 1% who reject this finding. The other 1.5 to 2% are the fence sitters — the undecided.
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One Planet Only Forever at 23:59 PM on 27 August 2015Tracking the 2C Limit - July 2015
I would like to see the 'lagging' likely temperature increase 30 years later due to a rapidly increasing level of CO2. I am referring to he 0.3 degree C value mentioned in "The 1C Milestone" SkS post.
As mentioned in that article it is likely that accumulated human impacts to date have produced a 1.3 degrees C warming from pre-industrial levels, not 1.0.
I am not sure how to best represent it. It is related to the rate of increase of CO2. But it is already in the trend of the temperature history. However, if people are assessing how much more impact can be permitted compared to what has already been created the recognition of the 0.3 C must be included in the evaluation.
Perhaps the best thing to do would be to identify a 1.7 C threshold line with a note explaining why it is on the chart.
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PhilippeChantreau at 23:31 PM on 27 August 2015Water vapor is the most powerful greenhouse gas
Venus is better described as having a bright side and a dark side, because of it slow rotation; talking about "daytime" implies that a location on Venus is going to have diurnal temperature variations as experienced on Earth, while not only it is better described as a "yearly" variation but there is also no significant difference between bright and dark side temperatures on Venus. "Daytime" is not an appropriate qualifier of anything on this planet.
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CBDunkerson at 22:41 PM on 27 August 2015Here’s what happens when you try to replicate climate contrarian papers
It is interesting that the factor making the paper difficult to get published was that it looked at multiple previous studies. Papers showing an inability to replicate the results of just one study get published all the time... almost routinely. Had it been split into 38 separate papers, each showing the inability to replicate a single previous study, it seems unlikely there would have been any controversy.
Thus, rejecting the 'composite' study because it didn't seek to perform a statistical 'meta analysis' of 'skeptic' vs mainstream replication rates or some other 'collective result' seems to be missing the point. They rejected it for failure to be what it wasn't... while overlooking that it was perfectly sound and replicable science for the issue it was actually looking at.
The other objection, that the paper clearly had a 'political' point in looking solely at 'skeptic' papers is true... but should have been irrelevant. Rejecting sound science because it has a political intent is, itself, a political decision.
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Kevin C at 20:31 PM on 27 August 2015Tracking the 2C Limit - July 2015
I'd drop CO2 too.
However there is an intriguing possibility: Plot
TCRCMIP5 x log2(CO2(T)/<CO2>1888-1909)
It then has the same units as temperature and provides an interesting model-obs comparison. Tough to explain though.
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bozzza at 20:12 PM on 27 August 2015Tracking the 2C Limit - July 2015
@6, ..talking about political targets 3 C is exactly what Bjorn Lomborg was hoping to convince the global voters of democracy that fossil fuels should be allowed to warm our kids earth by.
I just feel that this exact point needs to be made as science and politics are inextricably linked.
How much more political can it be to have the good name of a prestigious University used to flog fossil fules all in the name of enriching the elite?!!?
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ryland at 19:40 PM on 27 August 2015Here’s what happens when you try to replicate climate contrarian papers
I've read the account by Rasmus Bernestad in RealClimate and am intrigued by the journal shopping that took place in efforts to find a journal that would accept this paper. Perhaps unsurprisingly. the journal that finally accepted the paper had the lowest Impact Facor (1.759) of the five journals approached. The title of the paper "Learnng from mistakes in Climate Science" is, again perhaps, as applicable to the efforts of the authors in getting the paper accepted as it is to the papers they criticise in their paper. Quite honestly the efforts seem typical of academics operating under the threat of "Publish or Perish". That said congratulations to Dr Bernestad for presenting the saga so frankly. I would however ask Dr Bernestad not to use "fairly unique". Something is unique or it is not. There are no qualifiers
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Digby Scorgie at 18:31 PM on 27 August 2015Tracking the 2C Limit - July 2015
ecwiebe @1
As a retired technical writer I appreciate your point (3). I always made sure to keep a non-breaking space between number and unit. However, there is one exception — or at least there was when I investigated the matter a few decades ago — and that concerns degrees Celsius. In this case there is no space; in effect, the degree symbol fills the space between number and unit symbol (C). Interestingly, there is of course no degree symbol when kelvins are used. I think the anomaly with Celsius arises from the fact that it is a non-SI unit.
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shoyemore at 17:37 PM on 27 August 2015Here’s what happens when you try to replicate climate contrarian papers
M Tucker
I think Dana's statement that Galileo's conclusions were based on empirical evidence is defensible. After all, he was actually observing the Moon and planets through a telescope.
However, I too would cast doubt on the statement that Galileo was supported by "many scientific contemporaries". They were just not many scientists around! As far as I know, Jesuit astonomers like Father Clavius, who was respected by Galileo, were willing to compromise on Galileo's theory by treating it as a method of calculation of orbits rather than physically true. However, Galileo was just not the compromising type.
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Tom Curtis at 15:45 PM on 27 August 2015Water vapor is the most powerful greenhouse gas
PhilippeChantreau @215, perhaps, but half the planet remains in night at all times even so. I suspect I have missed your point.
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Ger at 15:03 PM on 27 August 2015Here’s what happens when you try to replicate climate contrarian papers
https://en.wikipedia.org/wiki/Galileo_Galilei; he stept on some very powerfull toes (and his theory was flawed)
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PhilippeChantreau at 14:45 PM on 27 August 2015Water vapor is the most powerful greenhouse gas
Well, personally I think that talking about "daytime" temperature on a planet that takes longer to rotate on its axis than to orbit around the Sun speaks more about one's ignorance than any other enormity he could profer...
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Tom Curtis at 14:37 PM on 27 August 2015Water vapor is the most powerful greenhouse gas
re:AJ Virgo @212, I can well imagine a stunned silence when it was claimed the daytime temperatures of Mecury and Venus being "about the same" disproved the existence of a atmospheric greenhouse effect, but it is the stunned silence that shows complete disbelief that anybody could so flaunt their ignorance of basic science.
Let's start with the basics. Mercury is closer to the Sun than Venus. Therefore, because of the inverse square law, Mercury recieves far more radiation than Venus. Three and a half times as much per meter squared, as it happens, and six and two/thirds times as much as is recieved by the Earth per meter squared. All else being equal, as a result of this we would expect the skin temperature of Mercury to be 120 K greater than that of Venus, and 169 K greater than that of the Earth.
All else is not equal, of course. In particular, the bond albedo of Mercury is just 0.068, compared to 0.9 for Venus and 0.306 for Earth. That is, Mercury reflects away just 6.8% of radiation that falls on it from the Sun, compared to 90% for Venus and 30.6% for the Earth. Once we factor that into the equation, we expect a skin temperature of Mercury of 439 K, compared to just 184 K for Venus, and 254 K for Earth. Ergo, absent any greenhouse effect, we absolutely do not expect the daytime (and night time, winter or summer) surface temperature of Venus to excede the maximum surface temperature on Mercury, but at 737 K, it does indeed exceed the 700 K maximum daytime temperature of Mecury.
Having ignored elephants like the effect of Sun-planet distance on radiation recieved, and the effect of albedo, it is no surpise that AJ Virgo also ignores subleties such as heat distribution, comparing daytime maximum temperatures with Venus mean annnual temperature (which coincidentally is also its daytime maximum temperature due to its thick atmosphere and strong greenhouse effect). For what it is worth, the skin temperature, on a planet with no atmosphere, equals the surface temperature. As it happens the observed mean surface temperature of Mercury is 440 K, near identical to the calculated vaue.
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Rob Honeycutt at 12:23 PM on 27 August 2015Water vapor is the most powerful greenhouse gas
AJ Virgo @212... "We have been led to believe that the warming effect of CO2 is linear but it's logarithmic..."
Nope. The entire premise of climate sensitivity is a function of a change in temperature per doubling of CO2. That is, in itself, is a logarithmic function.
And that very premise dates back to Svante Arrhenius in the late 1800's through the early 1900's.
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AJ Virgo at 12:02 PM on 27 August 2015Water vapor is the most powerful greenhouse gas
We have been led to believe that the warming effect of CO2 is linear but it's logarithmic, decreasing in proportion to saturation. This means that after about 200ppm adding more will do near nothing.
Obviously if this were not true there would be no life on Earth.
This can be seen with Venus and Mercury which have about the same daytime temps yet Venus has an atmosphere %96 CO2 and Mercury near none.
This fact was brought up a few years ago and there was stunned silence then and stunned silence since, it killed the debate stone dead.
Laughably the politicians soon started saying "The debate is over" but they didn't know why !Moderator Response:[TD] See the post "Is the CO2 Effect Saturated?" Read the Basic tabbed pane there, then watch the video lower on that page. Then read the Intermediate tabbed pane, then the Advanced tabbed pane. Then read the article linked in the "Further Reading" box below the video. Then if you still are unconvinced, say so in a comment on that post's thread, not this one, and I will point you to two articles on RealClimate.org and some on ScienceOfDoom.com. Before commenting again, gain some knowledge and lose some attitude.
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Tom Curtis at 11:00 AM on 27 August 2015Ice age predicted in the 70s
LizR @58, Scientific American republished that article in 2008 "to offer an historical perspective on some of the issues being discussed at the United Nations Framework Climate Change Conference". The full original version including charts and illustrations has also been reproduced as a PDF here.
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Rob Honeycutt at 10:59 AM on 27 August 2015Tracking the 2C Limit - July 2015
Tom @11... That one is going to take a little more processing on my part. Let me work on it.
Tom @12... You know, I had thought of the same thing, but I'm having some trouble with Apple Numbers (not using Excel) where there seems to be a bug when I select log scale. When I select that the y-axis defaults to a min of 100 and a max of 1000, which totally messes up the chart.
That one is going to take some work too.
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scaddenp at 10:26 AM on 27 August 2015Ice age predicted in the 70s
This looks to be the G Plaas paper. You can find references and links to these early papers here including this one. See also the wonderful Weart book "The discovery of global warming".
For the sciam reference, see here. A republish of july 1959 article.
Note that this is offtopic. Please do not continue discussion in this thread.
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LizR at 10:07 AM on 27 August 2015Ice age predicted in the 70s
Does anyone have a link to the Scientific American article from the 1950s (or 60s?) called "Carbon Dioxide and Climate". So far I have seen only the attached rather blurred scan. I would like to read it (and find out the date!)
Moderator Response:[PS] Fixed image size
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Tom Curtis at 09:05 AM on 27 August 2015Tracking the 2C Limit - July 2015
Rob, with regard to CO2, it would be better to plot the log of CO2 against temperature rather than just CO2. If you want to use a linear measure, cumulative emissions has at least some scientific support as having an approximate linear relationship with temperature. As it relates to the chart, I can understand your reasons for not including a second set of values on the y-axis, but if you do not you need to be more explicit about how CO2 concentration values are related to the temperature values.
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Tom Curtis at 08:57 AM on 27 August 2015Tracking the 2C Limit - July 2015
Rob, using the Mann 2008 Global EIV reconstruction, the 1736-1765 average is -0.11 C using the same baseline as you do above. If we renormalize the reconstruction against the GISS LOTI, that becomes -0.12 C. That renormalization is appropriate given that the reconstruction is normalized against HadCRUT3, which distorts its values very slightly due to the reduced twentieth century trend shown by that (now obsolete) temperature index. In either event the difference from your assumed preindustrial temperature as reflected by your baseline is small, but your baseline will consistently underestimate the how near we are to the 2 C 'target'.
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Rob Honeycutt at 08:03 AM on 27 August 2015Tracking the 2C Limit - July 2015
jphsd... Yes, I'm aware of Victor & Kennel. But Stefan Rahmstorf did an excellent response to their paper on Real Climate titled, Limiting global warming to 2 °C – why Victor and Kennel are wrong.
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M Tucker at 07:41 AM on 27 August 2015Here’s what happens when you try to replicate climate contrarian papers
Dana,
I love this piece. I love this web site. You and your comrades do excellent and necessary work but please be careful with history.
"...Galileo, whose conclusions were based on empirical scientific evidence, supported by many scientific contemporaries..."
I’m sorry Dana but that is just not true but it is a widely held belief of those who are not aware of the actual history. Please don’t be one of those.
Sci Am had a great article last year, in the January issue I think, called “The Case Against Copernicus” that discusses the lack of empirical evidence during the time of Copernicus and Galileo. The many scientific contemporaries you mention did not exist. You could also visit a wonderful site called Renaissance Mathematicus. Thony Christie is a superlative historian of science of the Early Modern Period and he has a special section called The Transition To Heliocentricity: The Rough Guides because so many folks keep getting the actual history wrong.
If you get the history wrong when trying to correct the mistakes others are making with the history your argument loses its justified force. This is a friendly suggestion to check your history before publishing.
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jphsd at 07:36 AM on 27 August 2015Tracking the 2C Limit - July 2015
Here's the link to the Nature article: Victor and Kennel (2014)
Moderator Response:[PS] Fixed link. Please use the link button in the editor in future.
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Ed Wiebe at 07:35 AM on 27 August 2015Tracking the 2C Limit - July 2015
It ocurred to me later that my point 5 about being above or below the 2 °C limit can be resolved by saying "above" or "below". No need then for a negative sign.
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Rob Nicholls at 06:56 AM on 27 August 2015Tracking the 2C Limit - July 2015
I think this is a great way to focus people's minds on the looming danger of over 2 degrees C of global warming unless humanity acts very quickly and decisively to build a low carbon energy infrastructure and massively cut its greenhouse gas emissions.
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Rob Honeycutt at 05:16 AM on 27 August 2015Tracking the 2C Limit - July 2015
jphsd... I wouldn't agree that 2C can be defined as "purely" political. If it were purely political then any number could be chosen, and it certainly would be far easier to politically agree on 3C or 4C. And I also don't think anyone defines it as a specific "threshold that we shouldn't cross."
There is a lot of scientific basis that revolve around the figure. We clearly increase our risk of crossing tipping points the higher we go. We also know that the Eemian was somewhere around 2C over Holocene preindustrial.
I think one could define 1C over preindustrial as "dangerous." 1.5C is clearly more dangerous than 1C... 2C more dangerous than 1.5C, and so on. Each point requires different levels of mitigation and adaptation, with a point somewhere along that continuum where mitigation would become ineffectual.
What I would agree with is that the exact selection of 2C is relatively aribitrary. But ultimately, it is important to draw a line in the sand somewhere and stick to that line as a defined measure.
As for the "threshold", no one is saying that this side of 2C is safe and that side is dangerous. Again, it is a continuum of escalating danger. I see the 2C limit as being a sign post continuously warning us that we have a critical global crisis ongoing.
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jphsd at 03:37 AM on 27 August 2015Tracking the 2C Limit - July 2015
Per David Victor, it's always worth pointing out that the 2C target is purely political and has no basis in science as some threshold we shouldn't cross.
2C was chosen by UNFCCC because it was believed (back then) to be an achievable target both technically and politically in the timeframe being discussed.
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bwilson4web at 03:30 AM on 27 August 2015Tracking the 2C Limit - July 2015
Sorry, I see the "12 month" label on the purple line.
Bob Wilson
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bwilson4web at 03:26 AM on 27 August 2015Tracking the 2C Limit - July 2015
The 'purple' line does not look like a 30 year, straight-line average but some smaller interval. I recommend making it 365.25 days or one year so seasonal changes disappear.
Also, a straight-line average is easy to compute, it has the bad habit of suppressing local minimums and maximums in the data. More work, I prefer a Gaussian weight average so random forcing functions like El Nino/La Nina and volcanic erruptions are seen in the data.
The other problem of a time-range, trend is the data lags by 1/2 the interval. You can include today's data in a one year average but the mid-point of the average is six months earlier. There are techniques that can allow showing 'current data' but it leads to subsequent versions 'moving the dot.'
Last, if using excel, use a calculated trend line and compare it to the excel generated trend line. I've been disappointed by the excel trend line function in the past.
Bob Wilson, Huntsville AL
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Rob Honeycutt at 03:26 AM on 27 August 2015Tracking the 2C Limit - July 2015
Thanks for the feedback, ecwiebe. This is definitely going to be an ongoing project with many updates along the way. A few responses, though.
1) We discussed this internally. My own take was that I really wanted to add the CO2 curve in there as a reminder of what's causing this. But adding the second data axis ended up visually confusing. The exact same data is presented as a second chart below with the y-axis data included.
2) Let me think about that one. I've always used the "C" without the degree symbol primarily because in the general course of typed communication, it's impossibly slow to add. But in a static chart like this it's less problematic.
3) That's easy to fix.
4) I'll see if I can squeeze the axis labels in there for next time.
5) Very good point as well about "degrees until 2C." I hadn't thought of what that number becomes when we reach 2C.
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Ed Wiebe at 02:06 AM on 27 August 2015Tracking the 2C Limit - July 2015
This is a good idea. However, I have a few of concerns about the first figure you've shown and since this appears to be the beginning of a long process I'm going put them here for you to consider.
1) You are showing two different quantities on a chart with one axis that has no units defined. That axis seems to be indicating °C at present. Also, these are temperature anomalies. Yes, that is hinted in the figure caption with the words "baseline period ..." but it probably should be stated in the axis label as well.
You need two axes and sets of axis labels for this plot unless somehow the variables have been normalized against the same dimensionless scale. I doubt that's the case but if it is it needs to be explained.
2) The unit for temperature is °C. Think of that as a single character that should be used in place of C. As far as I'm concered not using °C is just wrong regardless of how commonly it's done. °C should be a single character in the character sets of the world as far as I'm concerned. Is it?
3) units should always be preceded by a (non-breaking) space. You've done this inconsistantly in the same figure. e.g. '12m', '1.060 C'
4) though it may seem obvious, the time axis needs to be labelled with years or those units must be explained somewhere.
5) I don't care for the term, "2C Limit" but I recognize it's a name for "2 °C Limit". I don't think I can persuade the world to change that. On the chart you have "Degrees until 2C". This one I can't abide. Try, "Difference from 2 °C". At present you have "0.940 C" which is 2 °C - 1.060 °C = +0.940 °C. When we (inevitably) get above the 2 °C temperature anomaly this number will become negative. Is that really the way you want to think about it? I think it's backwards.
On the whole I think this is a good idea and obviously you can take my comments or leave them, it's your project. -
Here’s what happens when you try to replicate climate contrarian papers
bvangerven - As I see it, the 97% consensus is pretty clear on anthropogenic GHgs, increased radiative effect, attributions, etc. While the remaining 3% couldn't agree that the sky is blue....
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bvangerven at 19:36 PM on 26 August 2015Here’s what happens when you try to replicate climate contrarian papers
The fact that the 3% "skeptics" don't agree with each other is a very strong point. I would like to see some statistics on that : what % of skeptic papers claim "there is no warming", "climate sensitivity is low", "everything is uncertain" etc ? And how many climate skeptics contradict themselves ?
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denisaf at 09:50 AM on 26 August 2015Adapting to air pollution with clean air stands in China
The article deals with only one of the problems created by the operation of industrialized civilization. The holistic problem is that the vast, irrevocably aging infrastructure is irreversibly using up limited natural material resources and producing immutable material waste. Air pollution is one consequnce of the latter. Climate disruption and ocean waming and acidification are others.
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PhilippeChantreau at 07:16 AM on 26 August 2015New paper shows that renewables can supply 100% of all energy (not just electricity)
MA Rodger, correct. The extra drag is still there and I would be interested to see how airplanes whose mission traditionally requires cruise just below the transsonic range will fare (airliners and business jets). Few people realize when they fly that the safe airspeed window for an airliner at cruise altitude may be only 20 or 30 knots wide. Beyond that lie the risks of strucutral damage or controllability problems, below that a stall waits for you; high altitude stalls are no fun and recovery will likely put you in overspeed, with the issues I just mentioned.
In any case, we would be looking at an entirely new generation of airplanes, built from scratch, with an equally new infrastructure to support them, and a blank slate on safety. Such a transition would take a lot of time and be a little dificult to bridge. Currently existing airplanes can be relatively easily converted to use carbon neutral fuels, already have their infrastrucure, and their development includes all the improvements made every time there was an accident. These are important considerations. Airplanes are always compromises, the best possible for the type of mission to be flown. How we will power them will likely be that way too. I'm all for the best possible solution.
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scaddenp at 06:50 AM on 26 August 2015New paper shows that renewables can supply 100% of all energy (not just electricity)
ianw01 - using petroleum to create plastics by and large is binding the carbon rather than releasing it into the atmosphere. The problem is petroleum is using it for energy. I dont see 100% renewable energy as being incompatiable with continuing to use oil for plastics.
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shoyemore at 03:46 AM on 26 August 2015Here’s what happens when you try to replicate climate contrarian papers
There is a thorough discussion on this paper at Real Climate, moderated by Rasmus Benestad. It includes contributes to the discussion from Ross McKittick and Richard Tol, who both had opportunities to review the paper in an earlier form and who both advised against publication at that time.
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MA Rodger at 03:19 AM on 26 August 2015New paper shows that renewables can supply 100% of all energy (not just electricity)
PhilippeChantreau @67,
You get me re-visiting the Cryoplane Report because what you say is familiar but not complete. The summary of the report states:-
Following features resulted from comprehensive calculations and parametric studies for the above listed rage of aircraft categories.
① Due to the bigger wetted surface of the aircraft due to H2 storage in pressure vessels the energy consumption would increase by 9% to 14%.
② The OWE (Operating Weight Empty) may increase by roughly 23% by having additional tank structure,
③ while the difference of the MTOW (Maximum Take-Off Weight) will vary between plus 4,4% to minus 14,8% depending on the aircraft configuration and mission.
All this will result into an increase of the operating costs by 4% to 5% caused by fuel only.
The numbers for ΔMTOW were given as:-
Business jet -5.2%
Small Regional a/c +0.3%
Regional prop a/c +4.4%
Regional jet a/c -2.4%
Medium range a/c -2.7%
Long range a/c -14.8%
Very long range a/c -1.6%Thus the reducted weight of fuel load equals or exceeds the extra weight of the unloaded a/c in all bar one circumstance. Thus, I was mainly correct but perhaps overly optimistic with my all-encompassing "far greater than the structural weight" comment @65.
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Dcrickett at 02:38 AM on 26 August 2015Here’s what happens when you try to replicate climate contrarian papers
Not cherry picking, just nit picking:
"The one thing they seem to have in common is methodological flaws like cherry picking, curve fitting, ignoring inconvenient data, and disregarding known physics."
Are not "cherry picking" and "ignoring inconvenient data" pretty much the same thing?
I am grateful for this research.
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PhilippeChantreau at 01:56 AM on 26 August 2015New paper shows that renewables can supply 100% of all energy (not just electricity)
MA Rodger, as a long time pilot and flight instructor (although on light airplanes). I do appreciate the fuel load of modern airplanes. As someone familiar with the basic aerodynamics of flight, I also understand the relationship between weight and lift requirements.
The problem of all alternate ways to power aircrafts is energy density, which is very high with hydrocarbons. Hydrogen has a greater energy density per mass, but a much lower energy density per volume, and carrying it at the kind of pressures that would alleviate this problem requires heavy steel tanks. Liquefying it is the best option but carries its share of problems. Here is a excerpt from the source you cited:
"A key issue was to model the liquid hydrogen fuel system architecture - per unit of energy, liquid hydrogen has four times the volume of kerosene - so fuel tanks four times as large needed to be fitted in, or on to, each aircraft category. Modelling showed that, owing to the larger exterior surface area needed to accommodate the fuel tanks; energy consumption would increase by 9% - 14%, as would the maximum take-off weight. Overall operating costs would increase by 4% to 5% due to the fuel alone."
I did not misread this at all. Vast reservoirs containing a much lighter fuel but way more total volume of it. Bulkier and heavier airplane because of the additional storage volume.
Everything in an airplane has a cost. Any item is weight for which lift has to be generated. Large areas to accomodate large volumes of fuel imply more sheet metal, hence more weight, even if the total fuel weight is the same. Large areas also mean more drag, so more energy required for taek-off, climb and cruise. More weight means sturdier landing gear, which itself will have to be heavier as a result. Etc, etc.
Then of course, there is the issue of having fuel in the structure in the event of a crash. Engineers also have to assess the survavibility of a forced landing. Powering an large transport airplane is not a benign problem. I have no particular attachment with any solution.
From purely technical considerations, I remain of the opinion that synthetic hydrocarbon fuels capturing atmospheric carbon are a better option in the short and medium term than hydrogen. And that's not even considering all the infrastuscure associated with commercial transport airplane operations, another non benign consideration.
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One Planet Only Forever at 00:08 AM on 26 August 2015Adapting to air pollution with clean air stands in China
Instead of choosing between adaptation and mitigation, I prefer to think of the required action as an adaptation that will mitigate the impacts of human economic development.
The required adaptation is the open admission that much of the currently developed perceptions of prosperity, wealth and power are illusions that are not justified and need to be shattered.
There is a belief that the current measures of wealth and prosperity must be maintained and that the perceptions of the most prosperous must be maintained and continue to increase.
The required adaptation is a change of the way that wealth and prosperity are evaluated. And that change is required even if it means that many of the people currently considered to be very prosperous and wealthy are realised to not deserve the level of wealth or prosperity they have gotten away with developing.
That adaptation will clearly lead to the required mitigation. And it is also clear that without that adaptation, progress of humanity toward developing a lasting better future and lasting growth of the economy will continue to repeatedly fail as the undeserved perceptions of prosperity and wealth continue to be allowed to develop to the point of being impossible to gather popular support for.
It is also clear why that required adaptation and change by humanity will not be easy to achieve. But the difficulty in achieving it does not change the importance of it being successfully developed, the sooner the better.
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ianw01 at 00:01 AM on 26 August 2015New paper shows that renewables can supply 100% of all energy (not just electricity)
Plastics are made from certain fractions of petroleum. I have not seen any mention of how our demand for them would be met or replaced. The challenge goes way beyond using a cotton shopping bag - just look at all the surfaces and objects in your car, on your desk, at home and at your workplace.
I'm not objecting to the direction we have to move. Just trying to get my head around what for me is an astonishing premise in the original article.
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