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Glenn Tamblyn at 15:37 PM on 8 October 2015It's a natural cycle
billev
There are other factors to think about when evaluating what the temperature record may or may not mean
- It only represents warming of the atmosphere and this is only around 2% of the total energy being added to the climate. Around 93% of the extra heat is going into the oceans. And at the same time there are energy exchanges between the oceans and the atmosphere. Given the much larger size of the oean sink, even a small change in the size of this exchange could significantly impact atmospheric temperatures while being a trivial change in the oceans heat content. Even modest changes in circulation patterns could significantly alter air temperature trends
- Data from earlier than 1957 doesn't give coverage of the whole world and prior to the 1920's essentially both the polar regions were absent. Other evidencde suggests there may have been a localised warming occuring in the Arctic during the 20's and 30's at exactly the same time that measurement coverage in the northern polar regions was in flux - not an ideal situation.
- There is a recognised bias in the dataset from the period around WWII associated with changes in the nationality of the shipping fleets taking sea surface temperature measurements - the main contributor to the temperature record - due to the war.
- Looking at temperature trends for days vs nights also suggest that there was a stronger daytime cooling during the 40's to 70's period than nighttime which may have continued warming. If different tims of day are responding differently that suggest multiple factors at work when the sun is shining and not - warming due to CO2 over the entire day counteracted by daytime cooling due to increased air pollution is a possible explanation.
The take-away from this is we can't make a judgement about what was going on back then without putting all the pieces of data we have together like a jig-saw puzzle rather than focusing on just one type of data set. And recognising that when we look back to the mid 20th century and earlier many of these datasets are significantly missing/sparse - ocean heat content for example.
What we have now is that all measures of what is happening - ocean heat, sea level, ice sheet melt, land temperatures and atmospheric temperatures are all pointing to warming.To be a natural cycle the data would need to show different masurements indicating opposite trends as energy cycles between different internal parts of the system. If air temperatures were rising as ocean heat was falling (and the size of the changs was comparable) then we might suspect a natural cylical flow between the two.
The basic conservation Laws - Conservation of energy, mass etc. - require that any natural internal cycle between components of the system produce opposite cycles in the different parts. If all parts of the system are moving in the same direction then internal cycles can't explain it.
This doesn't rule out external cycles such as changes in the Sun's heat output - separate evidence mitigate against them - but all factors moving in the same direction does mitigate against internal cycles.
Basic premise, as pointed out by others. Cycles don't just happen, they always have causes. And those causes must satisfy the conservation laws.
To paraphrase 'S#!t doesn't just Happen! It is Caused'. -
Paul.H at 12:23 PM on 8 October 2015Skeptical Science reader survey - thanks for your feedback!
lol at bitter denier comments, because what else is here to do at this point.
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MA Rodger at 09:59 AM on 8 October 2015CO2 lags temperature
Tom Curtis @496.
I think you are asking for more than tatelyle is capable of providing. Consider his track record down this thread & make your own judgement. Below I collate the interchange that led to your comment @496. It is interesting how often tatelyle actually argues against what is his own misunderstanding. Even tatelyle's attack on Hansen & Sato (2012) leads him to his back of a fag-packet calculation @494 which looks to me as though he perhaps also mistakenly multiplied by the number of cigarettes in the packet, because with the model tatelyle tries to use the albedo effect seems to confirm Hansen & Sato. But, of course, that would never do because with tatelyle it is ABC - anything but carbon.
☻ TC@481 "(M)ilankovitch cycles can only significantly effect global temperatures if there are, not just feedbacks, but differences in th feedbacks that depend on location and season."
☻ tl@487 to TC "(You say ) Milankovitch cycles require feedbacks?
I understand all your arguments, that overall insolation cannot change much. However, the critical season and region for Ice Age modulation is the NH summer at northerly latitudes, because of the large NH landmass, as you say. It is this insolation that will decide whether the winter ice sheets melt, and so it is this region that will modulate Ice Ages."
☻ TC@489 to tl "Causing "winter ice sheets" to melt is a feedback. Further, it is a seaonal and regional feedback. If the seasonal and regional feedbacks in all areas and seasons were equally strong, then that feedback would be balanced by other, opposite feedbacks."
☻ tl@490 to TC "(you say) feedback would be balanced by opposite feedbacks because the changes in global annually averaged insolation balance out? But that is not true is it? - because as you said the NH and SH are very different, and so there is no 'balance' or equivalence between them.
So although the Ice Age becomes a global phenomina, it is triggered and forced by northern hemisphere Milankovitch forcing and only by northern hemisphere forcing. That is an indisputable fact."
☻ MAR@492 to tl "Answers on how ice ages happen are not simple. So are you then still happy to assert "So although the Ice Age becomes a global phenomina, it is triggered and forced by northern hemisphere Milankovitch forcing and only by northern hemisphere forcing. That is an indisputable fact."? (My bold)
☻ tl@493 to MAR "I was trying to counter the previous statement by Tom that 'Causing ice sheets to melt is a feedback'. Sorry, that is wrong. There needs to be a trigger, before feedbacks can assist in that process. Tom was trying to undermine the value of NH Milankovitch forcing, and I think I have successfuly countered that argument."
☻ TC@496 to tl "The brazen assertion that "Causing ice sheets to melt is a feedback" is wrong evidently needs some clarification."
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PhilippeChantreau at 09:50 AM on 8 October 2015The Republican Party stands alone in climate denial
"climate is giving the US on average more of a flogging than most other places"
I'm really not so sure about that. Last week-end 20 persons died in Southern France (in the region often referred to as the Riviera or "Cote d'Azur") because of extreme rain and floods. Some were stuck in their garage, a family was trapped in their car in a tunnel that filled with water. Rescue workers logged over 1000 interventions with 23 helicopter retrievals.
It didn't make the news in the US, too busy about their own catastrophic floods in the South-East. Perhaps the good legislature there can also ban the word "flood" from public discourse, like they did with "accelerating sea-level rise".
It is rather ironic, and yet denial is as entrenched as ever in the so-called conservative part of the population. It seems that no amount of evidence and no severity of adverse event can bring them back to reality. Meanwhile, we are splitting hair about the meaning of Hansen's exact words in 1988 or some other piece of nonsense. I am becoming more and more convinced that this experiement will have to run its full course. Maybe that end result will be beneficial after all is said and done.
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scaddenp at 08:43 AM on 8 October 2015The Republican Party stands alone in climate denial
"climate is giving the US on average more of a flogging than most other places"
It is? I dont think ramifications of drought in California quite on same scale as drought in Syria. The same could be said of many other weather events exacerbated by climate change.
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scaddenp at 06:21 AM on 8 October 2015It's a natural cycle
I would reinforce what Rob said. You will find it very hard to get people to accept the idea of a natural cycle that violates conservation of energy. Temperatures change for a reason.
However, on an unevenly heated planet that is mostly covered in water, there are natural variations in surface temperature from the ocean. You dont need much heat loss from the ocean upper layer to heat the air quite a lot. Rather than look at surface temperature, try looking at ocean heat content. eg see here Changes to incoming solar (eg volcanoes) are reflected in the wobbles. The steady upward trend however is a diagnosis of long term energy imbalance - the increase in GHG.
So to claim "its a natural cycle", then you need to be pointing to either an externality (eg change in volcano screening or change in solar input), or an internal variation - ocean-atmosphere heat exchange. You can see latest OHC here. Externalities cant explain post-1970 heat rise, so must be internal? Nope. Claiming heat is from oceans while ocean heat is rising is voodoo climatology.
That said, if your "skepticism" about AGW is based on political values or group identity, then I doubt anything posted here will change your mind.
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Rob Honeycutt at 03:46 AM on 8 October 2015It's a natural cycle
billev... No one has any obligation to satisfy you with their explanations. The explanations merely need to be correct, which they are. Previous commenters have given you very clear and accurate explations as to each of the various time periods. No one is trying to hide anything.
I believe I stated this before: Warming doesn't just happen for no reason. It is a response to a radiative forcing of one sort or another. Prior to 1940, warming was a combination of increasing human emissions of CO2 and other natural factors. Post 1940 was likely due to increasing aerosol emissions due to rapid industrialization. Post 1970 was when we cleaned up much of those aerosol emissions which unmasked the underlying CO2 forcing.
Just because you can't understand or manage to accept these explanations does not in any way reflect on their accuracy.
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billev at 03:33 AM on 8 October 2015It's a natural cycle
Regardless of all of the mind reading about my intentions, my original post only pointed out what I observed in the NOAA mean temperature record from 1880 until around 2000. I pointed out that I perceived two periods of warming and two periods of pause in warming during that period. The replies to my original post have been an attempt to explain away the pauses using several explanations none of which satisfy me as being realistic. What I do note is a desperate need to hide the pauses or avoid any involvment of nature in the pauses so plainly shown in the NOAA graphs.
Moderator Response:[Rob P] - The warming from 1910-1940, a time of weak anthropogenic (human-caused) forcing, matches the warm (positive) phase of the Interdecadal Pacific Oscillation (IPO) - the largest natural multidecadal oscillation in the climate system. This is the dominant 'natural factor' that other replies in this comment thread have alluded to. The cooling mid 20th century occurred during the cool (negative) phase of the IPO.
So the cooling back then wasn't only down to increased industrial aerosol pollution blocking/scattering some of the incoming sunlight, the IPO also played a part. Perhaps the most notable aspect of the IPO is that its influence on global temperature has diminished over time - it's being overpowered by the greenhouse gas forcing.
Some useful reading here:1. Early twentieth-century warming linked to tropical Pacific wind strength - Thompson et al (2014).
2. Drivers of decadal hiatus periods in the 20th and 21st centuries - Maher et al (2014).
[JH] You are now skating on the thin ice of excessive repetition which is prohibited by the SkS Comments Policy.
Please note that posting comments here at SkS is a privilege, not a right. This privilege can be rescinded if the posting individual treats adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum.
Please take the time to review the policy and ensure future comments are in full compliance with it. Thanks for your understanding and compliance in this matter.
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tatelyle at 03:28 AM on 8 October 2015CO2 lags temperature
>>The trigger is synchronised to the 100ky orbital eccentricity.
No it is not. Count the years. The trigger is synchronised in the later Ice Ages with increasing NH Milankovitch insolation, which is directly linked to the 25,700-year precessionay cycle. So the cycle length is either 102,000 years or 128,000 years, as you can see.
Big difference. Wrong cycle equalls wrong explanation.
>>'which is the primary feedback' is presumptive.
Not sure why. There are always greater and lesser feedbacks. But now we have identified the correct cycle that regulates Interglacials, we are in a better position to identify the primary feedback. And since Interglacials are SOLELY triggered by increased NH insolation events we can be pretty sure that CO2 is not the primary feedback. If Co2 was thenorimary feedback, Interglacials could also be triggered by SH warming. But they are not.
The exclusivity of NH insolation triggers strongly suggests that albedo is the key factor and the key feedback regulating Interglacials. And as we know the actual high latitude insolation and the actual ice sheet insolation increase is an order of magnitude greater that CO2 can manage.
Actual insolation increase 90 wm2 on the ice sheets (over whole Interglacial).
Actual albedo insolation increase 170 wm2 in northern latitudes (over the whole interglacial)
(Assumptions. NH insolation 460 wm2. Cloud albedo -80 wm2. Increase in albedo between ice and vegetation 50% or 170 wm2.)
So which is going to be the primary feedback? CO2's 4 wm2, or albedo's regional 170 wm2?
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bozzza at 19:30 PM on 7 October 2015CO2 lags temperature
If a gun is fired it doesn't mean the target will be hit.
Many things happened to make the gun fire and many things happened after the gun was fired.
This is complexity: now measure it!
("Um, What should we measure first and how?")
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RobH at 14:15 PM on 7 October 2015The Republican Party stands alone in climate denial
... of course, there is schaudenfraude in that the climate is giving the US on average more of a flogging than most other places. Like the gun issue, it is a interesting to see outright NRA supporters ending up gun victims. Sad though for the rest of the population.
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RobH at 14:03 PM on 7 October 2015The Republican Party stands alone in climate denial
Not so for Australia. Until the ousting of denialist prime minister Abbott, the Liberal/National government posted CO2 reduction strategies that are, and still are, nothing more than a fig leaf to cover entrenched denialism. Attempts to dismantle government agencies created by the previous Labor government to foster sustainable development were only stopped in the senate. In other cases, executive orders shut down funding for wind turbines. Statements to the United Nations in regard to Australia's climate change policy were nothing less than obfuscation if not downright lies. Our new prime minister Turnbull is fully up to speed with climate change but was originally replaced by Abbott over his positive stand onclimate change - so now has to play to the extreme right wing if he wants to keep his job. On this basis, Australia needs to get a flogging when it appears with its "fig leaf" policies in Paris in December.
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hankspage at 10:41 AM on 7 October 2015Skeptical Science reader survey - thanks for your feedback!
Didn't see the notice about the survey or would have replied. As someone who lives in Texas I'm really outnumbered when it comes to the deniers. I check this site every day or two to find news and often to find the real truth when the deniers send me some propaganda. They get upset when I reply with documented evidence I've found on this site to some climate change myth they are trying to pass as a fact.
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airscottdenning at 05:19 AM on 7 October 2015The Republican Party stands alone in climate denial
Extreme partisan polarization (the team sports analogy described in comment #1 above) combined with the enormous role of monetary contributions have amplified the absurd anti-science rehtoric of the political right in the US compared to that of other countries.
There's also the problem that professional climate communication has settled on a three-part message that fails spectacularly with these audiences: "it's real, it's us, scientists agree." This message works well with some people, but each part is challenged by "Team Red" with some success in public opinion.
People don't warm the climate; heat warms the climate! We see this every day (vs night) and every summer (vs winter). There's zero disagreement about this, even with conservative audiences.
Then we can move on to solutions. The Team Red position is that free market economies are fundamentally weak and must be subsidized by digging free stuff out of the ground. They argue that capitalism is powerless to solve an existential problem and has to roll over in the face of rising temperatures, water shortages, and rising seas. This is not consistent with free-market idelology. It is pathetic defeatism, and real conservatives need to call it out.
The political right must not bet its future on the premise that "heat doesn't cause changes in temperature." Rather, it must engage in a vigorous and full-throated debate that the free-market can offer the BEST solutions to the world's biggest problem. Team Red has been AWOL on advocating for free-market solutions. Not only is this a LOSER position, it also guarantees that actual climate solutions will come from Team Blue.
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ubrew12 at 05:07 AM on 7 October 2015The Republican Party stands alone in climate denial
Cartoonist Mike Luckovich's cartoon take on the probable cause of GOP climate denial.
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Kiwiiano at 04:58 AM on 7 October 2015The Republican Party stands alone in climate denial
Hopefully the record rainfalls in Carolina and the droughts & wildfires in the west will undercut their popularity as folk realise what is happening, assuming of course they actually need voters to turn out for them. The American political system is so disfunctional & corrupt they may not be needed.
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Rob Honeycutt at 23:55 PM on 6 October 2015Tracking the 2C Limit - August 2015
Thms... You know, you're absolutely correct. I forgot to pull down the data in my spreadsheet. When I did that I got the same answer as you. I'm still getting used to my own process. :-)
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Thms at 23:33 PM on 6 October 2015Tracking the 2C Limit - August 2015
Hi Rob!
We have almost exactly the same.
Your "In July we stood at 1.060C ..." is the "problem".
July means IMHO the current 12 month (July and 11 months back). I take July as starting month and additional the last 11 months.
You take for July the data from June and additinal the last 11 months.
I'm afraid my English is a bit rusty. -
Rob Honeycutt at 21:51 PM on 6 October 2015Tracking the 2C Limit - August 2015
Thms... I'm using the exact same data. Not sure why you getting a different answer.
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Tom Curtis at 21:44 PM on 6 October 2015CO2 lags temperature
tatelyle @493:
"I was trying to counter the previous statement by Tom that 'Causing ice sheets to melt is a feedback'. Sorry, that is wrong. There needs to be a trigger, before feedbacks can assist in that process. Tom was trying to undermine the value of NH Milankovitch forcing, and I think I have successfuly countered that argument."
The brazen assertion that "Causing ice sheets to melt is a feedback" is wrong evidently needs some clarification. Specifically, you commented on the origian articles claim that:
"In other words, increasing CO2 levels become both the cause and effect of further warming. This positive feedback is necessary to trigger the shifts between glacials and interglacials as the effect of orbital changes is too weak to cause such variation."
(My emphasis)
The inclusion of the two sentences is necessary to establish context, specifically that the articles claim about feedbacks related not to icesheet melt directly, but to the warming of the climate, ie, the increase in Global Mean Surface Temperature.
With regard to the claim in the article, you asked the question:
"The article states that CO2 is a feedback that assists Milankovitch cycle warming / cooling. Many commentaters here have also stated that Milankovitch influences are weak, and need a feedback to have any effect on climate. Can someone explain why?"
(My emphasis)
Given the clear context of the claim you were discussing, you were asking for an explanation as to why feedbacks must be inferred to explain the "... warming of the climate", ie changes in GMST. At least, if you were not, you were instead indulging in the rhetorically odious, and vacuous tactic of bait and switch. But, just to reinforce it, you yourself clearly reference effects on climate. Once again, ice sheet melt is not a change in climate, still less the more precise change in GMST required by context.
Formally, A is a feedback on B if and only if:
1) A is not B;
2) Changes in B cause changes in A; and
3) Changes in A cause changes in B.
As such, it seems straightforward that melting of icesheets are a feedback on global GMST. Specically, melting of ice sheets are not GMST (clause 1); changes in GMST can cause icesheets to melt (clause 2); and melting of ice sheets changes GMST by changing albedo (clause 3). Ergo, the only way you can deny that the melting of ice sheets is a feedback in the context of this discussion is to deny that we are talking about GMST (ie, genuinely be indulging in the odious tactic of bait and switch), or deny that either the melting of ice sheets can effect GMST, or that changes in GMST can effect the melting of icesheets. Neither of the later two seems at all probable. The first (denying that melting icesheets effects GMST flies in the face of all the ice core evidence), while denying the second amounts to denying that the changes of state of water are controlled by temperature.
I require urgent clarrification of what claim exactly you are basing your denial that melting of ice sheets is a feedback. Are you employing bait and switch tactics (ie, discussing feedbacks on the melting of ice sheets rather than as required by context and your prior statements, feedbacks on changes in GMST) - or are you making extraordinary claims without evidence (ie, denying either of the two relevant cause/effect relationships).
I also request that other commentors not engage with Tate until he has clarified what is the exact basis of his absurd rejection that ice sheet melt is a feedback. Prima facie, and absent clear clarification such, engagement is futile in that he is merely using rhetoric to mask confused thinking rather than honestly engaging in the discussion.
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MA Rodger at 19:34 PM on 6 October 2015CO2 lags temperature
tatelyle @493.
Can we then be clear then - Ice ages are triggered. Following this they are forced by feedbacks.
Concerning the trigger, the evidence suggests the trigger is NH insolation, in the late pleistocene this being synchronised to the 100ky orbital eccentricity cycle while in the early pleistocene this was synchronised to the 41ky orbital obliquity cycle. The trigger mechnanism is thus probably more a question of what primes the trigger than what the trigger happens to be.
Nothing about ice ages is straightforward. Even the events that began the ice age cycles at the end of the pliocene, events bound up with the closing of the Panama isthmus, events which caused both warming and cooling, even those events are not simple and obvious.
So to say "the trigger for Interglacials was NH Milankovitch ..., I think this is a correct statement." is not an end to the 'trigger' story. (Note you yourself @493 are speculating that dust was not present 170kybp preventing an interglacial occurring but was 150kybp for the creation of the Eemian.)
Then concerning feedbacks, once the ice age is in progress, the idea that feedbacks will drag the climate through the cycle is perhaps simple to grasp. But, while feedbacks can be listed out, the mix of feedbacks cannot be determined accurately enough to be certain of that mix. Thus your question @493 'which is the primary feedback'? is a bit presumptive, even as a genuine question. Why should there be a single primary feedback? All the evidence points to there being no single primary feedback. So the answer you yourself give to a misplaced rhetorical question "And I think the obvious answer is albedo."is not speculative. It is wrong.
Thus the moderator response pointing the need for reference (that you protest about @494) is no great surprise to me.
And the remainder of #494 reminds me so much of why I wrote the first paragraph @492. I would humbly suggest you revisit it.
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tatelyle at 19:00 PM on 6 October 2015CO2 lags temperature
>>Can you please reference your "obvious answer"?
Seriously? Are we not allowed to think for ourselves?
Can you see a flaw in my logic or argument?>> Hansen & Sato 2012 by contrast calculate albedo
>>and GHG forcings to be approximately equal.Yes, but Hansen has made a very basic error in this paper, that should have been picked up in peer review. Why was it not?
Hansen claims an equivalence between albedo feedback and sea level, and this is the basis for his albedo feedback calculation. So Hansen has smeared the albedo feedbacks out across the whole globe, much as Tom tried to do in post 489. But as I demonstrated in posts 490 and 493, the Interglacial initiation or trigger is SOLELY a function of increased northern hemisphere (NH) Milankovitch insolation, and so the feedbacks that assist this initiation are likely to be NH feedbacks as well. The southern hemisphere (SH) has nothing to do with the Interglacial warming process, as the Ice Age record in post 479 clearly demonstrates. Increased insolation in the SH never triggers an Interglacial, only the NH can do that.
So Hansen's smearing of albedo feedbacks across the entire globe is incorrect, and we can therefore double his 'insolation equivalent' calculation from the outset. So Hansen's 4 wm2 figure for albedo feedbacks suddenly becomes 8 wm2. But as I pointed out previously, the albedo trigger effect is mainly a local ice sheet condition in the higher latitudes, rather than a hemispherical response, mainly caused by surface dust and dirt, so there is no point adding the entire NH into this initial calculation. Ambient temperature is not the key to ice-sheet melting, direct insolation onto the ice sheet is, as was patently obvious on the Himalayan glaciers. But if that is so, then we can restrict the albedo feedback to the ice sheets themselves, and therefore multiply the albedo forcing-feedback by 5 (the area above 55º N). And this results in a true albedo feedback-forcing of 40 wm2 (about half the Milankovitch forcing value, over the complete Interglacial warming). Which is exactly what I said in post 491, but we have approached this new calculation from a different direction - Hansen's erroneous paper.
>>Furthermore it is not obvious how albedo
>>can create a NH-SH teleconnectionBecause of the hemispherical heat transport process, as in the following (simplistic) diagram, with tropical heat being exported to the poles. NH ice sheet melting will cause a large net increase in net energy absorption, not only on the NH ice sheet itself but also at the retreating margins. Each annual km of ice retreat at the terminus (that is about the rate of ice retreat), will have its albedo changed from about 60% to about 30% with sandy soils, and then to about 15% as plants reestablish themselves. I make that a 4 x 10(12) watts increase in absorption at 50ºN, each year. That is a large increase in the whole-earth energy radiation budget, that will be transported to the SH pole as easily as to the NH pole.
And once the world has begun to warm, there may then be some minor assistance to the process from CO2 and CH4. Correct me if I am wrong but my back of a fag-packet calculation for a 5,000 year ice retreat gives 4 x 10(12) w increase for albedo changes at 50ºN, annually, while CO2 influences averaged over 5,000 years are only 4 x 10(11) w. So CO2 on its own, without CH4 or H2O, is order of magnitude less in influence.
http://www.goes-r.gov/users/comet/tropical/textbook_2nd_edition/media/graphics/tropics_surplus_heat2.jpg
Moderator Response:[PS] Seriously, yes. Handwaving away a paper that is doing the hard maths is little better than sloganeering. If you can fault Hansen and Sato, then publish it. Other commentators are giving you guidance on your logic. Since I am moderating, I will try to stay out of it.
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Thms at 17:34 PM on 6 October 2015Tracking the 2C Limit - August 2015
I use GISTEMP LOTI: deviation August 2015 (average of the last twelve months: 2014.9 – 2015.8) of the baseline period 1880-1909 (average).
According to my calculation: August (2014.9 – 2015.8) is now 1.073C warmer than 1880-1909.
I did not use a moving average. My results are the same as in the article. Only the respective month has “slipped”. -
tatelyle at 04:44 AM on 6 October 2015CO2 lags temperature
Rodger,
Thank you for your considered reply and the additional datasheet.
When I said the trigger for Interglacials was NH Milankovitch (and an indespitable fact), I think this is a correct statement. The forceing trigger is Milankovitch, but this does not exclude feedback assistance following the initial trigger.
I was trying to counter the previous statement by Tom that 'Causing ice sheets to melt is a feedback'. Sorry, that is wrong. There needs to be a trigger, before feedbacks can assist in that process. Tom was trying to undermine the value of NH Milankovitch forcing, and I think I have successfuly countered that argument.
As to the subsequent feedback enhancement, you name a few possibilities, but the question then becomes 'which is the primary feedback'? And I think the obvious answer is albedo. A reduction of albedo from ice (say 50%) to soil (say 10%) is highly significant, giving a local summer daytime absorption increase of about 180 wm2. That is significant, especially if we now know the primary forcing-driver is a regional NH event (melting ice sheets), which subsequently allows worldwide warming. Remembering that all net warming is tropical, which spreads out over the globe, with the higher latitudes being constant net losers of energy.
And if albedo is the primary feedback for Interglacial warming, then the reason for the lack of response at 170k bp is equally obvious. In this scenario, higher latitude NH Milankovitch warming requires an albedo response to be successful, but the major dust storms did not occur until 150k bp. So the brilliant white 170k bp ice sheets could not melt at any insolation value; while the 140k bp ice sheets were dirty, primed and ready to go.
Tate
Moderator Response:[PS] Can you please reference your "obvious answer"? Hansen & Sato 2012 by contrast calculate albedo and GHG forcings to be approximately equal and match observed temperature well (Fig3). Furthermore it is not obvious how albedo can create a NH-SH teleconnection.
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Rob Painting at 04:26 AM on 6 October 2015The Republican Party stands alone in climate denial
The conservative government of New Zealand (the National Party) is effectively a closet anthropogenic climate change denying group. They generally don't explicitly deny the science or the observations, but they act no differently from those that do explicitly deny the science.
They have tampered with New Zealand's (carbon) emission trading scheme, so as to render it utterly useless, spend massive amounts of taxpayer dollars trying to entice oil drilling companies here, and do everything they can to exploit fossil fuels, whilst at the same time effectively discouraging the uptake of renewables. Fortunately, a legacy of the forward-thinking nature of previous generations and governments is that around 80% of our electricity comes from renewable sources.The climate system doesn't care whether governments explicitly or implicity deny science. All that matters is the amount of carbon dioxide we emit into the atmosphere. By that standard we are all failing and the consequences are likely to be devastating.
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Stephen Baines at 04:12 AM on 6 October 2015The Republican Party stands alone in climate denial
I think it is worth keeping the terms "idelogically driven" and "partisan" separate. Once is presumably a difference based on a philosophical position - and ideology such as democratic socialism or economic libertarianism. As mentioned, modes of regulation of GHG's exist that appeal to those idelogical positions, although we can argue about their effectiveness.
Pure partisanism is simple identity politics. I think of it as sports politics — my team is good, your team is bad, no matter why you or I chose a team in the first place. It has a simple tribal appeal, but in it's pure form eventually leads one to take positions that don't make much sense — like supporting a favorite player engaged in spousal abuse, or thinking that market based approaches to controlling fossil fuels or health care are good as long as the other party doesn't promote them. Generally, people are more likely to double down when faced with such threats to their identity, taking ever more extreme positions to maintain some semblance of consistency.
I think it's important to discriminate. People on opposite sides of an ideological divide can still communicate, because there is a basic logic underpinning their positions. People on opposite sides of a sporting conflict cannot compomise, because the very purpose of such a divide is to have a "self" and an "other." It is an emotional ego-based appeal that has immense power to motivate individuals to action because they feel personally threatened.
I think republican strategists in the US have been very effective at using identity politics to their electoral advantage - via the Southern strategy, the urban vs rural divide, the migrant/native divide. They are not the first party in history to do so, not by a long shot. You can argue that is the trick of politics, to marry policy to such identity based motivation. But they are also slowly being backed into narrower and narrower corners on a range of topics where they look to be on the wrong side of history — GHG and climate change being just one very imoprtant example. I don't think it's a strategy that can work for ever.
How (or if) they will transition out of it is a really good question. I have a feeling that they rode the bull out of the chute, fell off and are now being dragged behind it. At times I am disheartened, but at others I think that this strategy may have reached a natural end, and maybe we will soon get to a proper discussion of what we want to do about a real problem.
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MA Rodger at 02:08 AM on 6 October 2015CO2 lags temperature
tatelyle.
You ask difficult questions but that is because you appear to seek answers that are simpler than the situation merits. Do also bear in mind that the full mix of forcings that result in ice age cycles is not yet fully determined which makes an informed answer a tad harder still.
Examine that graphic @479. At first glance, the last ice age shows a reasonable match between Antarctic temperature and July insolation for 65ºN. But look again. There is a good wobble-for-wobble match but there is also a ramping down of temperature over the ice age. This ramping shows there is something else at work other than NH insolation. And look at the graph for the ice age previous to the last one. The wobbles are a far poorer match but the ramping down remains a strong feature. Further, if the ice age cycles were solely about NH insolation, why didn't the insolation maximum 170ky bp, a maximum larger than that which saw the last ice age replaced by the holocene, why did it not have the power to create an inter-glacial warming?
Things get more interesting when we look at the Greenland temperature record. The graphic below is Figure 1 from EPICA (2006) which compares Antarctic temperatures with NGRIP from Greenland.
There are things afoot in the NH that are certainly zip to do with insolation.As well as insolation, we have ice albedo, CO2, CH4 and dust and added to that climatic effects. A quick back-of-the-fag-packet calculation suggests the annual energy flux arriving at 65ºN from insolation, something like 100Wm-2 ±7Wm-2, is about the same size as the net energy from the South warming latutides at 65ºN, mainly through the atmosphere.
Answers on how ice ages happen are not simple. So are you then still happy to assert "So although the Ice Age becomes a global phenomina, it is triggered and forced by northern hemisphere Milankovitch forcing and only by northern hemisphere forcing. That is an indisputable fact."? (My bold)
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Thms at 01:20 AM on 6 October 2015Tracking the 2C Limit - August 2015
In July we stood at 1.060C and August is now 1.074C.
In my humble opinion in June (2014.7 – 2015.6) we stood at 1,060 and in July (2014.8 – 2015.7) at 1,074.
August (2014.9 – 2015.8) is now at 1,073.
Please correct me if I am wrong!
Moderator Response:[JH] Please tell us what the numbers you cite are and document their source.
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tatelyle at 00:28 AM on 6 October 2015CO2 lags temperature
Actually, I would like to take back that 6.5 wm2 that I calculated above.
Spreading the summer Milankovitch forcing all over the winter period makes no sense whatsoever. The ice-sheets are in perpetual lock-down for the winter, and nothing happens, so the ambient temperature is irrellevant. It is only the summer melt that is meaningful. And when I was doing research on the Himalayan glaciers, melting only occurred during sunny days, while during cloudy days and nights the glacier remained frozen.
And if we erase the winter dilution that was suggested, the Milankovitch forcing on Ice Ages is more like 16 wm2. And it may well be more than that, for I see no reason for spreading this forcing around the whole northern hemisphere. It is sunny days that cause most melting on a glacier, rather than raised ambient temperatures. We were in shorts and singlets during sunny days, even at 18,000 ft. So I think that this 16 wm2 should be doubled to something more like 32 wm2, to take into account the local or regional aspect of this melting process. That is the true increase in forcing of Milankovitch cycles on northern ice-sheets over the whole Interglacial warming cycle - 30 to 40 wm2.
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CBDunkerson at 21:43 PM on 5 October 20152015 SkS Weekly News Roundup #40
I was going to point out that 'rejectors' would inevitably be shortened to 'rejects', but... already there.
The problem I have with 'doubters' is that it is inaccurate for some of them. The people at Exxon who examined the problem, confirmed that global warming is real, and then spent decades telling the public that it wasn't are not 'doubters'. They know full well that global warming is real. 'Doubters and deceivers' would be accurate, but 'deniers' covers that in one word.
Still, 'doubters' is better than 'skeptics' in that it is only an inaccurate description of some, while 'skeptics' was inaccurate for nearly all.
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tatelyle at 19:46 PM on 5 October 2015CO2 lags temperature
Thank you again for your replies, but they are still not making complete sense. You said:
>> feedback would be balanced by opposite feedbacks because the
>>changes in global annually averaged insolation balance out.But that is not true is it? - because as you said the NH and SH are very different, and so there is no 'balance' or equivalence between them.
And I can prove this to you because in the graph in post 479, the Interglacial temperature rise closely follows northern hemisphere Milankovitch forcing, and not the southern hemisphere forcing (which would happen 12,800 years later). So although the Ice Age becomes a global phenomina, it is triggered and forced by northern hemisphere Milankovitch forcing and only by northern hemisphere forcing. That is an indisputable fact. So Interglacial forcing and warming is asymmetric and regional, not global.
So there is no 'balance' as you call it. Ice Ages are caused by NH conditions, and so your spreading out the NH forcing across the globe, and thereby reducing it to just 2 wm2 is completely erroneous. Firstly, the NH summer melt is 40% of the year, as you know. And secondly, the SH is completely irrelevant, as we has just been demonstrated. So the Milankovitch forcing is actually 6.5 wm2, before any feedbacks have been added.
So why would CO2 be important in this process?
Your assertion that CO2's influence is significant is based upon a doubling of CO2, or 3.7 wm2. But that assertion is completely erroneous and misleading. The initial CO2 increase at the beginning of the Interglacial warming is about 20 ppm, and this equates to less than 1 wm2. And why would less than 1 wm2 have any influence on world temperature? So what will be the primary driver - 6.5 wm2 of Milankovitch warming, or less than 1 wm2 of CO2? And since a warmer NH summer during an Ice Age is going to produce melt, exposing dirty old ice, the primary feedback is more likely to be reducing albedo than increasing CO2.
>>Citing denier blogs lends the opposite of credibility.
What a silly comment. Why are comments like this tolerated on a serious blog? I did not cite anything, I borrowed a standard graph that is present on hundreds of web pages. So do you have an issue with that graph? Do you consider it incorrect or misleading in any way? And if not, then why the silly comment?
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uncletimrob at 18:59 PM on 5 October 20152015 SkS Weekly News Roundup #40
@ubrew12, Sadly while I agreee with you, it is probably a loaded description rather than one that refleects their grasp of the science.
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ranyl at 18:48 PM on 5 October 2015Emphasizing co-benefits motivates people to take action on climate change
"even for those unconvinced climate change is real."
There are also those those who HAARP on and others who behold the creator's hand as the reality of things.
Wonder what would convince the oil producing countries, companies and ISIL to stop selling fossil fuels?
What army would or could war or protect without fossil fuels?
Holy war with promised salvation versus eating local produce, using as little power as possible and sharing for those around you etc......?
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ubrew12 at 15:35 PM on 5 October 20152015 SkS Weekly News Roundup #40
Jonas@1. Great idea. However, in the interest of brevity, how about just call them 'rejects'?
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Nate12674 at 09:37 AM on 5 October 2015Was Broecker really the first to use the term Global Warming?
There is a book published in 1971 called 'Energy' by John Holdren (yeah that guy) and Phillip Herrera, which is sort of a textbbook. In it I was quite amazed to see a couple of pages discussing future global warming due to the CO2 greenhouse effect. It gives a suprisingly accurate estimate of the warming expected by the year 2000, of 0.8C. And it accounts for the trends of the previous 70 years in a way more or less similarl with today's explanation. It further explains that this small warming could cause sea level rise and changes in the global circulation patterns that would impact agriculture, etc.
The book cites a 1970 workshopat Williams college on "Man's Impact on the Global Environment" as a source (MIT press).
Whether or not they had coined the term by then, it is impressive how much the experts knew was coming by 1970.
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Tom Curtis at 08:52 AM on 5 October 2015CO2 lags temperature
tatelyle @487:
"I understand all your arguments, that overall insolation cannot change much. However, the critical season and region for Ice Age modulation is the NH summer at northerly latitudes, because of the large NH landmass, as you say. It is this insolation that will decide whether the winter ice sheets melt, and so it is this region that will modulate Ice Ages."
Causing "winter ice sheets" to melt is a feedback. Further, it is a seaonal and regional feedback. If the seasonal and regional feedbacks in all areas and seasons were equally strong, then that feedback would be balanced by other, opposite feedbacks because the changes in global annually averaged insolation balance out (for all intents and purposes). It would follow that there would be no net change in GMST. That is the point of the arguments above. Ergo, when you say "I understand all your arguments" but "feedback", which is essentially what you have said, you clearly do not understand the arguments at all.
"And as that Milkanovitch graph shows, the critical summer NH insolation can change by up to 25% during the Milankovitch cycle. Not a few wm2 here or there, but a whopping 90 wm2. So why would the 4 wm2 provided by CO2 be significant, in comparison to the 90 wm2 of the Milankovitch cycle?"
The Earth has 46 million kilometers squared of area North of 55 North, out of a total of 510 million kilometers squared. That represents 9% of the Earth's total surface area. Further, Summer constitutes just 25% of the year. Ergo, your 90 W/m^2 at 65 North in Summer is equivalent to 2 W/m^2, globally averaged. So why would the 3.7 W/m^2 globally averaged forcing from a doubling of CO2 by more significant than the 2 W/m^2 globally averaged milankovitch forcing when we ignore everything but the milankovitch forcing in Summer in the high NH? Or the less than 0.4 W/m^2 globally averaged forcing if we include the full milankovitch forcing?
Your original question was why do we need to infer strong feedbacks given that the seasonal/regional milankovitch forcing was strong. Even only considering that forcing (ie, ignoring the opposite milankovitch forcings in other regions or seasons), the globally averaged mean annual temperature would only change by 0.65 C without feedbacks. In practise it changed by about 5 C. Further, the SH temperature changes have the same sign, and approximately match the size of the NH temperature changes. That would be impossible unless at least one of the feedbacks was necessarilly global in nature, and quite strong (to counteract the opposite signed local milankovitch forcings in the SH).
Moderator Response:[PS] rate matters too. The change of forcing at 65N only per century is about 2 orders of a magnitude smaller than rate of change of in CO2 forcing globally.
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Daniel Bailey at 07:45 AM on 5 October 2015CO2 lags temperature
Citing denier blogs lends the opposite of credibility.
Moderator Response:[PS] debunking such nonsense however is however largely what this site is about.
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tatelyle at 01:57 AM on 5 October 2015CO2 lags temperature
Thank you for your explanations. However:
>>Milankovitch cycles require feedbacks.
I understand all your arguments, that overall insolation cannot change much. However, the critical season and region for Ice Age modulation is the NH summer at northerly latitudes, because of the large NH landmass, as you say. It is this insolation that will decide whether the winter ice sheets melt, and so it is this region that will modulate Ice Ages.
Thus obliquity, precession and eccentricity must ALL effect ice sheet extent. Obliquity will obviously increase summer warming at high latitudes. Precession will also increase summer warming at high latitudes, when synchronised with obliquity. And it is the NH summer melt that is important, rather than the global energy budget. And therefore it is high latitude NH insolation and albedo that are important.
And as that Milkanovitch graph shows, the critical summer NH insolation can change by up to 25% during the Milankovitch cycle. Not a few wm2 here or there, but a whopping 90 wm2. So why would the 4 wm2 provided by CO2 be significant, in comparison to the 90 wm2 of the Milankovitch cycle?
>>Once that ocean carbon store is exhausted, no
>>more extra CO2 is reaching the atmosphere.
Thank you, but I do not follow that argument. CO2 solubility can proceed all the way up to 60oc, so why would the 'CO2 store' be exhausted at say 20oc? If the average southern ocean temperature in an Ice Age is 10oc, then the reducing solubility of CO2 in the ocean should continue at almost the same rate all the way to 20oc or more. So why would the outgassing of CO2 stop during an Interglacial, just because the southern ocean has reached its current 15oc temperature?
http://www.rocketscientistsjournal.com/2006/10/_res/CO2-06.jpg
Thank you,
Moderator Response:[Rob P] - "Thank you, but I do not follow that argument."
Read the links I provided to you earlier, particularly the recent Watson et al (2015) paper. Here's the abstract:
"Atmospheric CO2 concentrations over glacial–interglacial cycles closely correspond to Antarctic temperature patterns. These are distinct from temperature variations in the mid to northern latitudes, so this suggests that the Southern Ocean is pivotal in controlling natural CO2 concentrations. Here we assess the sensitivity of atmospheric CO2 concentrations to glacial–interglacial changes in the ocean’s meridional overturning circulation using a circulation model for upwelling and eddy transport in the Southern Ocean coupled with a simple biogeochemical description. Under glacial conditions, a broader region of surface buoyancy loss results in upwelling farther to the north, relative to interglacials. The northern location of upwelling results in reduced CO2 outgassing and stronger carbon sequestration in the deep ocean: we calculate that the shift to this glacial-style circulation can draw down 30 to 60 ppm of atmospheric CO2. We therefore suggest that the direct effect of temperatures on Southern Ocean buoyancy forcing, and hence the residual overturning circulation, explains much of the strong correlation between Antarctic temperature variations and atmospheric CO2 concentrations over glacial–interglacial cycles."
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Jonas at 23:09 PM on 4 October 20152015 SkS Weekly News Roundup #40
Referring to the AP article on "deniers" -> "doubters".Why not call them "rejectors" in the headline and at first occasion in the text define as "those who reject the mainstream scientific consensus" ?
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denisaf at 14:47 PM on 4 October 2015Emphasizing co-benefits motivates people to take action on climate change
The simple fact is that irreversible rapid climate disruption and ocean acidification and warming is under way because of the the contribution of emissions from past fossil fuel usage to operate the vast industrial infrastructure. The most poeple can possibly do is make sound decisions about the use of the infrastructure as that will contribute to slightly slowing down this misuse of natural forces.
Saying that measures can be adopted to cure climate change is grossly misleading as it can encourage the adoption of ineffective amelioration measures when the rational approach is to adopt measures to cope with the inevitable consequences of climate change, such as sea level rise.
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grindupBaker at 12:55 PM on 4 October 2015Satellites show no warming in the troposphere
David Arthur @ 17 "Water molecules absorb sensible energy at the surface when they evaporate, and re-release that energy at whatever tropospheric height when they re-condense. That is, intensification of the water cycle results in energy "bypassing" tropospheric greenhouse gases as it departs earth." is incorrect per the following table. Note that the *current* increasing greenhouse gas effect is mostly above the point at which 90% of water vapour resides (<~4km altitude) so there's lots of that +CO2 at 4km-~16km altitude to send some radiation back down. (the tabs didn't work out, figure it out yourself):
alti- air air
tude tempe- density --— atmospheric ppmv --
km rature g/m3 CO2 water vapour
0 16 1,290 400 14,000
0.5 12 1,235 399 11,000 **84% already caught and shimmering around**
1 9 1,180 398 8,500
1.5 5 1,130 398 6,400
2 2 1,075 397 4,900
3 -6 965 395 2,900
4 -13 860 394 1,700
5 -20 750 392 1,000
6 -27 680 390 600
** zone above approx. this height has more CO2 than H2O **
** zone above approx. this height is not "saturated" with GHGs **
** zone above approx. this height produces most +CO2 & +CH4 warming **
7 -34 610 389 350
8 -42 540 387 200
9 -49 470 386 120
10 -56 420 384 70
11 -56 370 384 40
12 -56 320 381 25
15 -56 200 376 10 ** 37.6x as much CO2 as H2O **
** not much +CO2 & +CH4 warming above approx. this height, air too thin **
20 -56 90 368 8
25 -52 40 360 8
30 -47 20 352 8
40 -25 5 344 8
50 -3 1 336 7
60 -18 0.39 328 7
70 -50 0.125 320 5.5 to 6.5
80 -83 0.027 312 2.5 avge (2 to 4.5) -
Tom Dayton at 09:25 AM on 4 October 2015Examining Hansen's prediction about the West Side Highway
Willis Eschenbach on WTF just repeated this myth about James Hansen's "prediction" of the West Side Highway being covered by now.
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grindupBaker at 08:57 AM on 4 October 2015Was Broecker really the first to use the term Global Warming?
It would have been gooder if a few scientists had gotten together some decades ago and provided a definition of "global warming". The present eclectic mix of alleged definitions that I've seen are poor quality with a few having some hilarity aspect, and a waste of time in debate. Anthropogenic global warming is surface warming caused by humans that's mostly caused by humans as I understand it.
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r.pauli at 01:45 AM on 4 October 2015Emphasizing co-benefits motivates people to take action on climate change
Gosh golly, sounds like a call for people to band together and form, um, gulp, "governments".... better yet, a global government!
Thanks for calling attention to this study. I read the summary as academic language expressing a common rule of business "Nothing will change unless there is money to be made or money to be lost" It is almost as if the Ideology of capitalism is blackmailing the future by saying to the world "We refuse to act until we see a balance sheet reason that can dictate an action"
Preferable is a modicom of prudent foresight based on science. Understand science or not. Better put: "Change or die" -
Neither Benevolence nor Development can exist in an over-heated world. Shouldn't we be past these two approaches? It is more like the choice to avoid chaos and suffering or accept it. The convincing will come from the real world - either from now risk or from future risk.
How much energy do we put into convincing Ideologues? Promising economic development is a tough sale. Adaptation sells itself and there will be plenty of business opportunity in building walls against rising sea levels and selling water and food. Oh and security and military.
Mitigation, however should be our only goal - yet even with full devotion of resources - results will be invisible for at least 40 years - then must continue for a thousand. Isn't it important to see the harsh reality?
"Prepare to join the Mitgation world government army!, Resistence is futile" - we are the Borg - er, make that the GORB (Government of Realistic Beings)
thanx for all you do
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kar at 18:25 PM on 3 October 2015OA not OK part 3: Wherever I lay my shell, that's my home
There seams to be several minor errors with wrong loading carbonate ions as well?
CO3- and not CO3--
Moderator Response:[Rob P] - Thanks for pointing out those typos. Hopefully someone who has access will correct them in due course.
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kar at 17:58 PM on 3 October 2015OA not OK part 3: Wherever I lay my shell, that's my home
A small typo to correct on this page - search for: will dissolve will dissolve
... and remove two words ...
;-)
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Tom Curtis at 11:43 AM on 3 October 2015CO2 lags temperature
It is usual, when discussing Milankovitch cycles, to dismiss any effect of obliquity on global, annual mean insolation based on the fact that the Earth is a sphere. I did it myself @481. As the Earth is an oblate spheroid, however, it is not strictly accurate. In particular, on the equinoxes, the Earth presents its minimum aspect to the Sun, showing an eclipsed area of 1.2737 x 1014 m2 to the Sun. As the Earth moves to the solstice (either winter or summer) it presents its maximum aspect, showing an eclipsed area of 1.2744 x 1014 m2. That represents a difference of 0.05% in recieved sunlight, or approximately 0.12 W/m2. That seasonal variation is much less than the 6.8% (16.2 W/m2) seasonal variation due to the eccentricity of the Earth's orbit.
As obliquity changes, the maximum eclipsed area (ie the insolation at the solstice) also changes, although the minimum eclipsed area (ie, insolation at the equinoxes) does not. Just as the variation due to the Milankovitch cycle for eccentricity (~0.175%) is much smaller than the seasonal variation, so also is the variation due to the Milankovitch cycle in obliquity much smaller than the seasonal variation. Specifically, it represents only a 0.01% variation in the solstice insolation. As the equinoctial insolation does not change, the variation in global, annually averaged insolation due to changes in obliquity will be much less than 0.01%.
For perspective, these factors are also less than the difference of treating the Earth as a perfect oblate spheroid, or allowing for the additional interception of sunlight due to continents, mountains and, of course, the atmosphere.
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billev at 01:09 AM on 3 October 2015It's a natural cycle
Tom, I want to thank you for your responses to my comments. We apparently do not agree but at least you showed enough interest to reply. I made the same comments on the site Watts Up With That and got no response. I was the man who wasn't there. My purpose in making the comments was to see if there was any acknowledgement of what I see as a possible pattern of stepped warming caused by more or less regular pauses in the overall warming trend. I think the current emphasis on man- made warming may be akin to the worry over an impending ice age that was propounded during the period of the Time magazine article I quoted. And there were more of that type of article at the time. I get the feeling we are getting a politically based bums rush about man-made climate change and too many scientists are being carried along. If there is, in fact, a pattern to the warming then I think it will be obvious by the end of the current century. Maybe we will then begin wondering why such a pattern should occur. I shudder to think of the money that will have been wasted before then on uneeded or ineffective measures to control the climate. I am 83 years old so it won't be my worry.
Moderator Response:[TD] billev, I'm going to take a chance by assuming you are sincere. You are blind to how rude you have been to everyone who has taken the (sometimes considerable) time to respond to you. "Rude" because you have ignored the content of every single response. The most recent example is your failure to even acknowledge any of the content of the "Ice Age was Predicted in the 70s" post that you have been pointed to multiple times. Instead, in your most recent comment you merely repeated your initial, incorrect, assertion. If you want to continue commenting on the Skeptical Science site, you'll need to respond substantively to the original posts and to other commenters' responses to you. In other words, you must engage in conversation. Otherwise you are merely sloganeering, which is prohibited by this site's comments policy.
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PhilippeChantreau at 23:24 PM on 2 October 2015It's a natural cycle
We've been down that road countless times before. The claim that "scientists predicted an ice age" has no basis in the scientific litterature. Billev tried to exploit the miserably inaccurate Time article to show that "scientists" showed a decrease in temperature and increase in sea ice in the 70's and such conclusions were completely absent from the scientific litterature, once again. Mass media wildly speculative and sensationalistic pieces pass as "scientists said" for the convenience of scoring rethorical points. Yawn.
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MA Rodger at 21:53 PM on 2 October 2015Ice age predicted in the 70s
The "most cited" 1970's article heading this SkS post does contain a grown-up bit of referencing that I don't see discussed in the comment thread here. The 1975 Newsweek article "The Cooling World" quotes from "a recent report by the National Acadamy of Sciences" which is the 1975 report by the Panel on Climatic Variation "Understanding Climatic Change: A Program for Action". This long report (a transcript of sorts here) is certainly not about global cooling but about the threat from any form of climate change.
Beyond that basic conclusion, the report does strangely pull its punches when it comes to CO2 emissions, even though CO2 is the first man-made impact to be listed and its impacts are then enumerated.
The corresponding changes of mean atmospheric temperature due to C0 2 [as calculated by Manabe (1971) on the assumption of constant relative humidity and fixed cloudiness] are about 0.3 °C per 10 percent change of C0 2 and appear capable of accounting for only a fraction of the observed warming of the earth between 1880 and 1940. They could, however, conceivably aggregate to a further warming of about 0.5 °C between now and the end of the century.
Yet the message that CO2 presents a threat is somehow lost, with the 'Program for Action' calling for research into climate rather than a reduction of CO2 emissions. Somehow the stark message of the Charney Report just four years later is absent, such conclusions overwhelmed by talk of other human impacts. The report gets bogged down with the likes of the theoretical potential of aerosol cooling (that "cannot be reliably determined from present information") becoming more important in future:-
Of the two forms of pollution, the carbon dioxide increase is probably the more influential at the present time in changing temperatures near the earth's surface (Mitchell, 1973a). If both the C0 2 and particulate inputs to the atmosphere grow at equal rates in the future, the widely differing atmospheric residence times of the two pollutants means that the particulate effect will grow in importance relative to that of C0 2 .
And the impact of waste heat (which logically could be a big problem if fossil fuels were replaced by thermally inefficient nuclear power) is considered along with other various albedo effects, all competing with the CO2 message.
Yet, there are certainly no predictions of a "cooling world", no ice age being predicted here. Rather, the message is that climate change is dangerous.
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