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ubrew12 at 19:55 PM on 13 May 2016The things people ask about the scientific consensus on climate change
I tell people that Scientific consensus is important less for Scientists, and more for Policymakers. And in lay discussions, the Policy is actually what is being discussed. The 'Do Nothing' alternative is promoted on the basis that the Science isn't 'proven' or 'complete' (which is an odd thing to promote, since logically an 'incomplete Science' should call us to 'Do twice as much of Something' if we were true conservatives). But if Policymakers admit that they aren't Scientists, then Scientific Consensus is the justification for action. On this topic, Policymakers of the last 30 years have taken the 'Do Nothing' alternative based on a 'whopping' 3-10% consensus of expert opinion. It's hard not to conclude they simply ignored the Scientists and made policy on the basis of intuition. We shall see how that goes.
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ConcernedCitizen at 19:33 PM on 13 May 2016CO2 effect is saturated
@Moderator: Right, so when I point out that I accept that CO2s GH effect isnt saturated but question the proposed explanation I am going to be blocked am I?
Tom Curtis@416
Air at 6,1 km is thinner, I now that, I already said its colder. How does putting an additional CO2 mollecule there cause warming? By changing kinetic into radiative energy and radiating it downwards.
The suggestion that there is a kind of 'CO2 lapse rate' just doesnt fit.
Moderator Response:[JH] Moderation complaint snipped.
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ubrew12 at 19:29 PM on 13 May 2016Coal made its best case against climate change, and lost
For 30 years, Richard Lindzen has been criticizing the Climate Models under apparently no pressure to offer a prediction alternative. Imagine Opthalmologist Lindzen ordering a patch on your one good eye because it wasn't seeing 20/20: "Trust me! You're better off blind!"
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DrivingBy at 12:35 PM on 13 May 2016Coal made its best case against climate change, and lost
@ OPOF
We can easily agree here: "There is an even less popular point regarding population."
I think you'll find that the rest is not a new idea, and is a hard sell. I was a bit off topic in my post, so I'll not pull the it further OT.
Moderator Response:[PS] Thank you. This thread is indeed drifting offtopic.
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One Planet Only Forever at 11:31 AM on 13 May 2016Coal made its best case against climate change, and lost
DrivingBy@4,
There is an even less popular point regarding population.
The highest consuming and highest impacting portion of the population is what needs to be reduced.
My preference would be for the most fortunate among humanity to be expected and required to be leaders of the advancement of humanity to a lasting better future for all. Anyone uninterested in being that kind of person, preferring to live life as a partying spectator, would choose to give up the opportunity for the life of a leader (and find the wealthier life opportunity unavailable to them no matter how tricky or secretive they tried to be).
The current system that excuses (and encourages) known to be unacceptable behaviour if it can be gotten away with, especially if it can be popular and profitable, clearly fails the needs of the future of humanity (as it focuses on meeting the desires of the most callous among us).
Total global wealth and food production has grown more rapidly than the population yet a significant portion of the global population still live short horrible existences. That clearly needs to change.
The elimination of the ability of the already most fortunate to continue to enjoy their undeserved perceptions of prosperity is a step in the right direction. It is a step that will need to be taken affirmatively by humanity in spite of the potential reactions from those who would try to fight against losing their ability to win rewards by behaving unacceptably.
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Digby Scorgie at 10:50 AM on 13 May 2016Skeptical Science wins 2016 NCSE Friend of the Planet award
mancan18 @9
For deniers to say that "correlation does not imply causality" dodges the fact that high levels of carbon dioxide are "associated" with high temperatures, and vice versa. Since CO2 levels are now high, the deniers have to admit that high temperatures are therefore to be expected — in other words, global warming has to be real.
To put it another way, the deniers can't have their cake and eat it. To use the correlation-causation argument they have to admit the reality of global warming. (This treats as a separate issue the adding of more CO2 to the atmosphere from burning fossil fuel.)
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DrivingBy at 23:04 PM on 12 May 2016Coal made its best case against climate change, and lost
Coal was a great step forward, 200 years ago, it brought us out of the era of wiping out forests for fuel, 12 hour workdays and travel by horse for the wealthy or by foot for the rest. Today's problems are mosqito bites compared to the harshness of life then, and fossil fuel provided the physical energy undelying that change.
Coal's time has now passed, we need to move away from carbon fuels (unless some clever soul figures out how to economically capture C02 emissions). We also need to reduce the world population unless we are willing to live with conflicts and poorer lives, but that is not a popular thought and probably never will be.
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CBDunkerson at 23:02 PM on 12 May 2016Coal made its best case against climate change, and lost
I'm surprised the contrarians were even allowed to testify given the rules of evidence. Possibly Minnesota is less strict than the federal court system, but generally only well established science can be presented.
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Tom Curtis at 22:28 PM on 12 May 2016CO2 effect is saturated
Frankly ConcernedCitizen has amply demonstrated his refusal to think clearly about this topic. I am no longer going to waste my time on him. When he is so wrapped up in his own "wisdom" that he does not recognize the air at 6.1 km is thinner than that at 6.0 km, and that consequently his own counterexample proves the claim he is disputing, it is completly pointless to continue any discussion. (Romans 1:22 applies.)
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Eclectic at 22:18 PM on 12 May 2016There's no correlation between CO2 and temperature
Ken @49, your question is answered in the thread "CO2 is not the only driver of climate".
Quickest to go to the comments column there, and see Bozzza's (@20) laconic quote: "aerosols" ~ which is the short story . . . that could be expanded slightly to: "increasing industrialization produced reflective aerosols which counterbalanced the rising CO2, until the ever-higher CO2 levels overpowered the aerosol effect by around 1970 [combined with some clean-up of aerosol emissions].
You will note Tom Curtis's (@21) longer explanation of additional factors which contributed to a "flat" 1940-1970 record.
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ConcernedCitizen at 21:06 PM on 12 May 2016CO2 effect is saturated
Tom Curtis@414
Not wanting to create a long thread, and to keep it trelevant to the theory postulasted here, I focused on heat transfer space, not from the surface and not internally, so it wasnt a refutation of the GH effect at all.
" but you neglect that the lack of greenhouse gases also reduces the introduction of energy into the atmosphere by absorption of thermal radiation from the surface, with the absorbed IR radiation from the surface being much greater than the emitted radiation from the upper atmosphere"
At the top of the atmosphere, where the additional CO2 mollecules are now radiating at higher altitude, you have said that less than 1% of energy is direct radiation from the surface which contradicts this statement.
"if we add more greenhouse gases the air needs to be thinner before heat radiation is able to escape to space"
Why? If it isnt direct radiation from the surface (in which case the energy is maintained regardless of what altitude its radiated at, and is very rare (free path lenght and all that)) then its a kinetic-radiative change of energy.
So, if a colision happens with CO2 at 6km and is radiated to space the photon's energy represents the temperature at 6km.
Add more CO2 and now more of the collisions happen at 6.1km with the photon's energy representing the temperature at that altitude.
This doesnt mean there is more heat in the system.
Better to say that adding more CO2 turns kinetic energy at 6.1 km into photons which have an even chance of being emitted towards the surface. ie, more GH gas = more back radiaiton.
Taking the Feldmanpaper data from the paper above, and using 370 and 390 ppm for CO2 at 2000 and 2010 MODTRAN gives a 0.3 wm^-2 forcing change, which isnt far off fro the Feldman value, so I am not doubting CO2 as a GH gas or CO2 non-saturation just that the mechanism proposed here isnt feasible.
Add CO2 and now we have
Look, I am not saying CO2 is saturated, but the mechanism proposed here doesnt hold water when you pull it apart, and you certainly havent explained it, all you have done is explain the GH effect.
Moderator Response:[RH] Removed excess blank space. Concerned Citizen, the process has been explained to you in a very detailed and accurate manner. You're skating on this ice at the moment.
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.
Link to the commenting policy is just above the comment window.
[PS] The detailed process with the maths is in the Ramanathan and Coakley paper pointed to earlier. Do you dispute that paper?
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mancan18 at 19:50 PM on 12 May 2016Skeptical Science wins 2016 NCSE Friend of the Planet award
Congratulations SkS, well deserved.
As for the greatest threat from AGW, it is quite likely to be, using Donald Rumsfeld terminology, an unknown unknown. Climate Scientists know what they know i.e. known knowns. They are also aware of the known unknowns but are not yet sure as to their likely impact. However, considering that the world is directly on a climate path that existed long before humans first evolved, then the global ecosystem that will exist long after fossil reserves have been burnt, if they are not left in the ground, is an unknown unknown. It may well be that the resulting global ecosystem may not be favourable to humans. Of course humans now have a limited ability to control their own evolution and create their own climate and ecosystems. Whether that will be enough to avert the more adverse impacts of AGW is also an unknown unknown.
Incidently, one of the best temperature graphics I have seen in recent times that shows the rise in global temperature since 1850, has been produced by Ed Hawkins, an academic from the University of Reading. It is worth a look. It might also be worthwhile for someone to create a similar graphic showing the rise in CO2, and run them side by side, even though the denialists will use the argument that correlation does not imply causality.
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Tom Curtis at 18:10 PM on 12 May 2016CO2 is not the only driver of climate
Ken Kimura @19, if you sum all forcings (ie, not just that from CO2) using the values estimated by Meinhausen et al (2011), the trend in the forcings from 1940 to 1970 is 0.0003 +/- 0.0007 W/m^2 per annum. That is, it is essentially zero, and may well have been negative. On top of that, there was a substantial El Nino early in the sequence and a La Nina following the volcanic eruption in 1965 which together with the very low trend in forcings may have tipped the temperature record negative.
Having said that, if you look at this model of the ENSO adjusted temperature responce to forcings, you will see to large temperature spikes around 1939 and 1945 that are not accounted for by the model and which also contribute to the negative slope. It is difficult to know that to attribute those spikes to. They may be due to unusually large forcing by Black Carbon during World War 2. They may also be due to an artifact in the temperature record due to the sudden, very large reductions in temperature coverage along with the simultaneious large changes in methods of measuring Sea Surface Temperature brought about by WW2.
What they are not due to is the Pacific Multidecadal Oscillation (which is captured by the ENSO signal) or the Atlantic Multidecadal Oscillation (which does not have a suitable pattern to explain the phenomenon). Nor are they due to a fundamental misunderstanding of the forcings, or the relative effects of natural and anthropogenic forcings. The model I linked to allows you to weight the various forcings, making natural forcings much stronger in effect than anthropogenic forcings if you desire. Any such attempt, however, greatly increases the number of temperature discrepancies. That fact shows conclusively that theories that attempt to explain the twentieth century temperature record without anthropogenic factors being the dominant factor post 1940 (and a significant factor prior to 1940) are doomed to failure.
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bozzza at 17:27 PM on 12 May 2016Skeptical Science wins 2016 NCSE Friend of the Planet award
You are saying desertification could get a guernsey for biggest threat?
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bozzza at 17:25 PM on 12 May 2016Arctic Ice Volume is diminishing even more rapidly than Area
Figure 2 only has a downward trend of less than ten years.
How does the trend look now in 2016?
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Tom Curtis at 17:19 PM on 12 May 2016Skeptical Science wins 2016 NCSE Friend of the Planet award
bozza @6, I don't think anybody knows what the biggest threat is, and certainly I do not. We know there are several very large threats but exactly which is largest depends on time scale and how much we push global warming; but in addition to that the error margins on how bad the threats are are such that a clear worst effect cannot be picked on a global basis. Even if we push global warming to the extreme, in which case the seasonal rendering of tropical regions of the Earth uninhabitable to humans due to heat stress may be pipped by the effect of deoxydisation of the oceans (the probable cause of the worst mass extinction todate). The later also has a less clear cut off so that it may occur at lower temperatures. These are likely the worst possible impacts from purely anthropogenic global warming. Ocean acidification and changes in the hydrological cycle (which involves both more intensive flooding, droughts and storms) are likely the worst impacts at more moderate levels by my inexpert estimate.
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bozzza at 17:16 PM on 12 May 2016CO2 is not the only driver of climate
..aerosols !
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brendan1 at 16:06 PM on 12 May 2016Coal made its best case against climate change, and lost
Thanks for the article and the graphics, I enjoyed the description of the law suit as well. We have been discussing the direct impacts of coal burning in my climate change course, which makes this article very relevant for me. Not only that, but we have also discussed the idea of social costs (by looking at K. William Kapp's writings on the subject), and I enjoyed the fact that you touched on that. It seems like if the true social costs inflicted by fossil fuel burning were made to be answered for by the companies who do it, no one would want to use this method for energy because of the massive costs. In a perfect world, the giant subsidies could go toward sustainable forms of energy instead. I don't know if this can ever happen in the United States in time.
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bozzza at 15:48 PM on 12 May 2016Skeptical Science wins 2016 NCSE Friend of the Planet award
Thus, Tom, this begs the question of what Climate Change has as it's biggest threat if not sea level rise?
I presume desertification...
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Ken Kimura at 15:01 PM on 12 May 2016CO2 is not the only driver of climate
If the unremitting rise of CO2 from industriail activities is the dominant factor, why did the global temperature decrease from 1940 to 1970?
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Ken Kimura at 14:43 PM on 12 May 2016There's no correlation between CO2 and temperature
I had read the article and still I did not understand why the global temperature did not increase
from 1940 to 1970. Could you tell me what is the main cause of it?Moderator Response:[PS] From the article, "If CO2 causes warming, why isn't global temperature rising over this period? To answer this, one needs to recognise that CO2 is not the only driver of climate. There are a number of factors which affect the net energy flow into our climate. Stratospheric aerosols (eg - from volcanic eruptions) reflect sunlight back into space, causing cooling. When solar activity increases, the amount of energy flowing into our climate increases. Figure 5 shows a composite of the various radiative forcings that affect climate."
Figure 5 shows all the factors other than CO2 affecting climate of the period and Fig 6 sums all them, positive and negative, to show little net forcing till 1970. Please take some time to study actually study and understand the figures.
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Ken Kimura at 13:02 PM on 12 May 2016There's no correlation between CO2 and temperature
The global temperature did not increase from 1940 to 1970.
How do you explain this?Moderator Response:[PS] Read the article. (Net forcings, see figures 5 and 6 on the intermediate version of the article). Warning: Asking questions without any interest in the answers is simply sloganeering and forbidden by the comments policy.
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Ken Kimura at 10:06 AM on 12 May 2016Ivar Giaever - Nobel Winning Physicist and Climate Pseudoscientist
From 1940 to 1970, the world industrialized nations produced far larger amount of CO2 than before due to the rapid economic growth.
However, the global temperature did not increase during the period(Figure 1).
How do you explain this?Moderator Response:[PS] This is offtopic here. Please see co2 temperature correlation. Climate responds to net forcings not just CO2. See the graph of net forcings versus temperature at bottom of article and make any comment on that topic, not here.
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Tom Curtis at 09:55 AM on 12 May 2016Skeptical Science wins 2016 NCSE Friend of the Planet award
John A. Broussard @4, the total land lost to date is to small to even show on the scale of a global map. Even a six meter sea level rise (not expected for several centuries) appears more as a highlighting of the coast rather than a significant land loss:
This does not mean sea level rise is insignificant. People living on river deltas (Bangladesh, much of the Egyptian population) or what are in effect extended sand bars (Florida) along with will lose almost all their territory from such a sea level rise. Further, 40% of the world's population lives in coastal areas and will experience some negative impact from sea level rise, either through increased storm damage and flood risk (due to slower drainage of rivers due to the elevated sea level); or through the necessity to move cities or major infrastructure several kilometers inland (or build massive sea walls to obviate that necessity, with the risk of a Katrina like catastrophe as a result).
Consequently, while the idea of an updated index of sea level rise impacts is a good one; using a global map to provide that index is unsuitable. On the other hand, in some areas local maps might be very useful.
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Tom Curtis at 09:44 AM on 12 May 2016CO2 effect is saturated
ConcernedCitizen @413:
"The quesiton isnt whether the GH effect exists, it is wether CO2 is saturated as GH gas."
You say that, but immediately mount an argument that, if valid, would mean there is no greenhouse effect, not that it was saturated.
"The suggesiton is this: A CO2 mollucule at 6 km radiates a photon upwards. This photon was either radiated out from the surface and stayed as a photon at 15 microns all the way up, and finally, this CO2 molecule was the last one in the chain, and the photon made it out to space."
In fact, both of these are true for very small parts (<1% at a guess) of the energy radiated to space by CO2 from the middle to upper troposphere. For most energy, it will have been radiated from the surface (68%), or transferred by latent heat or conduction (18%), or absorbed in the atmosphere from solar radiation (14%). From there, most energy transfers will have been by collisions with other molecules, with transfer to molecules travelling downwards as likely as those to molecules travelling upwards, and with lateral motion of molecules receiving energy as great as either upwards or downwards motion. Most upwards motion will be from emissions from molecules, but (firstly), radiation will be as likely to take energy downwards as up, equally likely to take it laterally as either; and the molecules radiating the energy are more likely to be H2O molecules in the lower troposphere than CO2 molecules (and hence have a different, but lower energy content per photon than that eventually radiated to space by CO2). Of course, some of the radiation will have been by radiated by other greenhouse gases (CH4, NO2, O3, etc) which typically have a higher energy content per photon than that radiated by CO2. Of course, energy radiated by a greenhouse gas other than CO2 will have to be absorbed by that same greenhouse gas (except for a small amount radiated by H2O) and then transferred to CO2 by collisions (probably mediated by collisions with N2 and O2). Even energy transferred by radition from CO2 and absorbed by CO2 will have different energies to that finally radiated to space because of doppler energy shifts, and pressure broadening (and a couple of other effects).
The net consequence of this is that:
1) Of the energy finally radiated to space by a single CO2 molecule, not all will have come by the same pathway except in very rare cases;
2) The energy finally radiated by CO2 to space will typical have followed a very convoluted pathway through the atmosphere, spending almost as much time travelling downwards as upwards, and twice as much time travelling laterally as either downwards or upwards (with different parts of the energy travelling different paths as per (1));
and (most importantly)
3) Because the lower layers of the atmosphere are warmer, and hence radiate more energy, and downward radiation is as probable as upward radiation at all levels of the atmosphere, the majority of energy entering the atmosphere (59%) will follow a convoluted path that returns it to the Earth's surface.
The upshot is that the convoluted pathway of energy from the surface introduced by the presence of greenhouse gases in the atmosphere serves as a filter limiting the escape of energy to space. There is a bias in that filter caused by the lower temperatures at higher altitudes which means that less than 50% of the energy escapes to space.
Unfortunately for your theory, none of this fits your simplistic analysis. In your analysis, either all radiation is upward only, in which case all energy emitted from the surface escapes to space without impediment. And indeed, if all radiation was upwards only, there could be no greenhouse effect - but such a situation is unphysical.
Alternatively, on your second scenario, energy is transfered upwards by collisions and IR radiation from the upper troposphere reduces the thermal energy relative to the case with no greenhouse gases: but you neglect that the lack of greenhouse gases also reduces the introduction of energy into the atmosphere by absorption of thermal radiation from the surface, with the absorbed IR radiation from the surface being much greater than the emitted radiation from the upper atmosphere. So, while the IR radiation to space cools the atmosphere, the IR absorption from the surface warms it at a much faster rate.
In both scenarios, you ignore essential features of the system in order to draw obtuse conclusions.Moderator Response:[PS] Thanks Tom. ConcernedCitizen, note that the effects of increased CO2 has been directly measured (see "Observational determination of surface radiative forcing by CO2 from 2000 to 2010") so it real despite your difficulties in understanding why.
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mitch at 01:50 AM on 12 May 2016Coal made its best case against climate change, and lost
Thanks for giving the background on the Minnesota lawsuit. I have been wondering why the case was in court. My expectation is that if other GHG lawsuits get to court they will have a similar outcome. The 'fossil fuel' scientists are too few and too old.
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John A. Broussard at 00:46 AM on 12 May 2016Skeptical Science wins 2016 NCSE Friend of the Planet award
It's time for a world map, posted on this site, showing the daily, monthly, yearly loss of land to the rising seas (e.g. recent disappearance of several islands in the Solomons)
An up-to-date depiction of lost land and threatened losses would be very effective in demonstrating the actual and approaching effects of global warming.
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dana1981 at 00:29 AM on 12 May 2016Skeptical Science wins 2016 NCSE Friend of the Planet award
Thanks!
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ConcernedCitizen at 22:59 PM on 11 May 2016CO2 effect is saturated
M A Roger @411
Tom Curtis @412
The quesiton isnt whether the GH effect exists, it is wether CO2 is saturated as GH gas.
The suggesiton is this: A CO2 mollucule at 6 km radiates a photon upwards. This photon was either radiated out from the surface and stayed as a photon at 15 microns all the way up, and finally, this CO2 molecule was the last one in the chain, and the photon made it out to space.
Or the CO2 mollecule was impacted by an O2, or N2 molecule and thus kinetic to radiative change happened, with the energy of the photon representing the energy at that altitude, ie, temperature.
The proposal here is that an additional CO2 mollucule at 6.1 km causes cooling. HOw so? Lets look at the wto cases. Either the photon was passed up from the surface, and this is the last CO2 mollecule in the chain, in which case it is pased out to space with exactly the same energy as before. Ie, no loss of energy, no warming.
Or, if the photon came from kinetic energy and was radiated out to space, then yes, the energy of the photon would be less, because it represents the temperature at 6.1 km, but if the CO2 mollecule werent there then this radiation wouldnt happen at all and the kinetic energy would have just stayed in the system.
So I dont see how the suggesiotn that 'A CO2 mollecule radiates from higer and colder' means additional energy in the system and hence warming.
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Rob Honeycutt at 21:57 PM on 11 May 2016Comparing models to the satellite datasets
Christy actually is comparing TMT with a similar comparison of the atmosphere from CIMP5 model. So, it's now what he's comparing that's misleading, it's how he's doing it.
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shoyemore at 17:55 PM on 11 May 2016Skeptical Science wins 2016 NCSE Friend of the Planet award
Congratulations!
Totally merited.
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Finnjävel at 15:57 PM on 11 May 2016Comparing models to the satellite datasets
Good article.
Though there is one point that needs more effort; comparing model based surface trend with satellite TMT channel trend. Of course the mid troposphere trend is lower than surface trend and TLT trend.
Satellite data nicely proves the greenhouse warming.
Important question is are the model runs direct surface temperature runs, or somehow tweaked to 10km. My guess is that it is just surface data.
So Christy is comparing apples and oranges.
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Tom Curtis at 07:54 AM on 11 May 2016Skeptical Science wins 2016 NCSE Friend of the Planet award
Congratulations to Skeptical Science, and individually to Dana and the two Johns (Abraham and Cook). A very well deserved award.
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scaddenp at 07:15 AM on 11 May 2016CO2 was higher in the past
MA Rodgers. Whoops! I did indeed miss the CO2(e). Good point. On that basis, we would indeed be heading for Miocene-type climate (eventually).
Bozza - based on past climate with assumed similar net forcings. It takes a very long time for icecaps for melt and change in albedo would be very slow till nearly gone.
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Rob Honeycutt at 04:57 AM on 11 May 2016Scientists are figuring out the keys to convincing people about global warming
MA Rogers... And, of course, at that point contrarians will flip completely the other way and say, "Oh yeah? That just means the GHE is saturated." ;-)
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MA Rodger at 23:02 PM on 10 May 2016Scientists are figuring out the keys to convincing people about global warming
Tackling the 400ppm CO2 is so small a quantity, I feel there is another argument that may have traction in the minds of doubters. In normal circumstances it would be true to say "0.04% is so tiny!" but is it really when we talk the atmosphere? That is not a normal circumstance as we are talking tiny tiny molecules and a troposphere 12km thick. (Hopefully I haven't suffered decimal point drift in this below.)
CO2 molecules are today above 400ppm by volume or 607ppm by weight within the atmosphere. As the atmosphere weighs 5.15 million billion tonnes, that means (with an atomic weight of 44), there are 42,800 trillion trillion trillion CO2 molecules up there.
Now, consider the physical size of each CO2 molecule, imagine each molecule presents an area towards the Earth's surface equal to just the size of one of its carbon atoms which are ~70 picometres in diameter (imagine the molecules all stood on their ends with the other two atoms hidden behind the first carbon atom). Given this, and with the globe having an area of 510 million sq km, a photon if considered to be a point object leaving planet Earth by the shortest route (straight up) through an average bit of atmosphere; that photon would have to pass unabsorbed through over 320,000 CO2 molecules to escape into space unhindered.
That suggests the atmosphere contains rather a lot of CO2, not rather a little.
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billhurley at 22:57 PM on 10 May 2016White House: Climate Change Poses Urgent Health Risk
I have heard to that hurricane intensity will increase but the number of hurricanes themselves will not. However, this confuses me. Aren't stronger tropical storms going to result too? Doesn't this mean they become hurricanes and thus increase the number of these storms?
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MA Rodger at 22:47 PM on 10 May 2016CO2 was higher in the past
Ravenken @64.
I feel scaddenp @65/66 is a little quick converting your measure ppm CO2(e) into ppm CO2.
The use of CO2(e) as a measure of climate forcing also has to take on board the anthroprogenic negative forcings which are less well defined but which will (indeed, can only) reduce the CO2(e) figure.
The net forcing equivalent to that during time past when CO2=500ppm is a good start point for considering when the globe would lose the southern ice cap. The northern one is more suseptable to increases in temperature. The IPCC suggest in this SLR graphic that a temperature rise above pre-industrial of ≈1.5ºC would see Greenland melt down. (Mind, the ≈ is a worry.) And as the summit drops to warmer altitudes, it would become a tipping point and irreversable outside a renewed ice age. So if Antarctica is 500ppm, Greenland would be 400ppm.
Of course these are very slow multi-millenia processes. The forcing from methane etc and also the negative forcings are short-lived compared with CO2. And even CO2 will drop over such long time periods. But then melting the very last snow flake on the planet (or just in the NH) is not some target we should be taking as something to avoid. We will be in deep deep do-do far far earlier than the arrival of an ice-free hemisphere or two.
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bozzza at 17:55 PM on 10 May 2016CO2 was higher in the past
@ 54,
What happens to the sensitivity predictions if we include the slow feedback of melting ice sheets?
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bozzza at 17:52 PM on 10 May 2016CO2 was higher in the past
ooh, also how does comment 66 alter things?
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bozzza at 17:50 PM on 10 May 2016CO2 was higher in the past
@ 65
I'm interested in this comment:
500ppm for sufficiently long period of time (1000s of years) is postulated to be enough for it to be more or less ice free at poles, (though Antarctica would likely retain some ice as much higher in altitude than north pole).
How did you come across that idea may i ask?
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bozzza at 17:48 PM on 10 May 2016Consensus on consensus
To further your basic point, Glenn:
Edward DeBono wrote a book called mechanism of mind saying that the mistakes of the system were what made it work. (It's an old book so it might be wrong...!!??!)
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scaddenp at 11:53 AM on 10 May 2016CO2 was higher in the past
Should have checked before commenting. There is evidence of Milankovich cycles operating in Pliocene and moderating the size of the West Antarctica ice sheet. See here. The milankovich forcing seems to have been operating since at least Oligocene (see here) but in the without low CO2, they did not precipatate ice ages. At 500ppm, our climate would likely be similar to the warmer Miocene.
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scaddenp at 11:41 AM on 10 May 2016CO2 was higher in the past
Current CO2 is 400ppm, not 490ppm. 500ppm for sufficiently long period of time (1000s of years) is postulated to be enough for it to be more or less ice free at poles, (though Antarctica would likely retain some ice as much higher in altitude than north pole). Note that in Pleistocene we have ice age cycle driven by Milankovich cycles. In Pliocene, there was no such ice age cycle although the Milankovich cycle was almost certainly present (driven by earth orbital mechanics) and CO2 was around 400ppm and solar input roughly the same.
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Ravenken at 10:12 AM on 10 May 2016CO2 was higher in the past
"Periods of low CO2 coincide with periods of geographically widespread ice ... This leads to the concept of the CO2-ice threshold - the CO2 level required to initiate a glaciation."
Sorry for my ignorance, CO2-ice threshold... my understanding is we are around 490 CO2 equivalent right now... Is the converse of deglaciation the same 'number'? Am I also correct that the current 'number' is 500?
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Rob Honeycutt at 05:23 AM on 10 May 2016Climate Bet for Charity, 2016 Update
Gotcha. Now I get what you're saying.
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pattimer at 03:01 AM on 10 May 2016Climate Bet for Charity, 2016 Update
I am sure you are on a safe bet though :-) -
pattimer at 03:00 AM on 10 May 2016Climate Bet for Charity, 2016 Update
What I mean by that comment is that you would end up with 0.209 after 120 months if the average continued as it has done for the these past years. ( I am not implying that this is what you expect) but it would end up at 0.109 if the remaining years had an anomaly of 0 ( and I am not implying that this is what Kiwi expects) -
Rob Honeycutt at 01:13 AM on 10 May 2016Climate Bet for Charity, 2016 Update
Yes. That's effectively what I've said, that KT's methods are going to end up with the same result in the end. Although, I'm not clear on what you mean when you say, "Your running average is effectively assuming that the remaining months will continue with the same average anomaly and Kiwi's is assuming that the remaining months will have an anomaly of zero."
That's not registering for me somehow.
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pattimer at 00:46 AM on 10 May 2016Climate Bet for Charity, 2016 Update
Rob. It seems to me that both these methods will come to the same when the 120 months are up.....Or am i missing something?Your running average is effectively assuming that the remaining months will continue with the same average anomaly and Kiwi's is assuming that the remaining months will have an anomaly of zero. It is no surprise then when an average of 0.209 over 5 years and 3 months will return a running average of 0.109 if remaining months are assumed zero. When the time is up these assumptions have no bearing on your final answer.
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