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Comments 42701 to 42750:
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The Skeptical Science temperature trend calculator
Nick Stokes - According to the Trend Calculator ("Show advanced options" dropdown), the default ARMA(1,1) coefficient calculation is derived from 1980-2010 data. Using 1980-2013 the reported trend is 1.56 ±0.42 °C/century, rather closer. I suspect the difference is due to different ARMA(1,1) calibration periods, with the arima function using the entire period by default.
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Tom Curtis at 12:12 PM on 29 August 2013How much will sea levels rise in the 21st Century?
jja @47 & 48, you may be seeking a worst case scenario, but you cannot just manufacture such scenarios from the whole clothe. For instance, using the RCP 8.5 forcings, and a transient climate response pegged to give a 4 C increase in temperature by 2050 as per your specification, and a equilibrium climate response of 4.5 (ie, the upper end of plausible values), the cumulative energy gain from the TOA energy imbalance from now till 2100 is 2110 Zettajoules. Thus my conservative estimate of midrange values is well within error of your "worst case" scenario. An "RCP 10.0 scenario" will only increase that to 3425 Zettajoules. In both cases, your 5 meter sea level rise requires far more than 5% of the energy stored in the system.
Further, thermal expansion of the ocean linearly correlates to increased temperature. The A2 scenario (approximately equivalent to the RPC 8.5 scenario) has an upper estimate for thermal expansion of 0.35 meters. Allowing for your greater temperature increase, that rises to 0.56 meters, well short of the 1.67 meters you assume. Therefore melting of ice must make up 4.44 meters of sea level in you 5 meter scenario. In consequence, your scenarios require the melting of the equivalent of 44% (RCP10) - 50% (RCP 8.5) by ice rafting in excess of that from normal melt and calving of icebergs. In total, you require the melting of the equivalent of 64% of Greenland's ice in just 90 years. Even your worst case scenarios do not make this plausible. You still require a well justified mechanism for such massive ice rafting.
Finally, you simply do not adress the issue of past precedents. The rate of sea level rise durring the transition from the last glacial to the holocene can be (very conservatively) estimated at 0.16 meters per century. With twice the mass of ice melted during that period than is currently available to melt from all ice sheets, and with the ice at lower latitudes and hence having a stronger ice albedo feedback, why did the ice melt so slow if you think a 5 meter sea level rise in less than a century is plausible? You are expecting 30 times the melt rate, and far more than that towards the end of the century. And you are expecting this with a weaker albedo feedback.
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Nick Stokes at 09:13 AM on 29 August 2013The Skeptical Science temperature trend calculator
KR,
Thanks, I should have looked more carefully at the discussion above. I did run the same case using ARMA(1,1)
arima(H,c(1,0,1),xreg=time(H))
and got 1.52+-0.404, which is closer to the SkS value, although still with somewhat narrower CIs.
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jdixon1980 at 08:53 AM on 29 August 2013CO2 limits will hurt the poor
Above I say "there is a very uncomfortable balancing of policy considerations to be done."
By that I don't mean to imply that I think the right course is unclear, necessarily. If it's between slowing (not halting, mind you) the alleviation of the worst poverty in the world by only allowing/helping those regions to industrialize mostly if not exclusively through non-emitting energy sources like wind/solar/hydro/geothermal/yet-to-be-perfected fourth generation nuclear/current riskier nuclear, on the one hand, and on the other hand destroying the stability of the climate to the point where mass extinction is a near certainty and the very survival of humanity is in question, obviously it is a no-brainer - we should choose not to destroy the planet.
It would be even more of a no-brainer if alleviation of poverty can be done just as rapidly and effectively without fossil fuels (using all those other energy sources) as with fossil fuels, though I doubt that is the case.
So I guess my question is, how much agreement is there as to the so-called "tipping points" that would highly likely lead to mass extinction / survival of civilization being in question? To the extent that it is "speculative," does that even matter, considering we should err very much on the side of caution when the planet is at stake?
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jdixon1980 at 08:34 AM on 29 August 2013CO2 limits will hurt the poor
skept.fr @1 I share your objection. The fact that CO2 rise and the resulting global warming impacts will disproportionately harm the poor is clear, but that is not inconsistent with the the notion that emissions reductions/limitations/caps will disproportionately harm/burden the poor. So there is a very uncomfortable balancing of policy considerations to be done.
I understand that carbon budgets proposed for climate mitagation tend to be more generous for developing countries, as they ought to be from both an equity/fairness standpoint (atmospheric CO2 being for all intents and purposes cumulative, rich countries have already heaped on way more than our fair share to keep the total within acceptable limits), and a utilitarian standpoint (people in subsaharan Africa, for example, obviously stand to improve their lives a lot more by emitting a little more CO2 than we stand to be burdened by emitting a lot less CO2).
Obviously it wouldn't benefit the most disadvantaged for richer countries to continue BAU, unless you buy into some kind of global trickle-down benefit that they will get from our marginally greater prosperity and thus greater charity/aid/whatever.
But it seems to me that the question remains to be addressed here whether mitigation of future harms from CO2 outweighs the benefits to today's poor of allowing them to rapidly industrialize by the cheapest means possible.
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MThompson at 07:50 AM on 29 August 2013Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
Phil @78,
Thank you for your answer. I was indeed inquiring about KR@72 statement that "The electron relaxation time for a CO2 molecule is on the order of 10-6 seconds ..."
Furthermore, it seems that 10e-6 seems much too slow for relaxation of electronic states, and rather too fast for IR vibrational states.
Gratitude for furthering my education on this,
-M
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Phil at 07:02 AM on 29 August 2013Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
KR and MThompson,
The excited electronic states of CO2 do not play a particular role in the Greenhouse effect. Any molecules that are in excited electronic states will have slightly different vibrational frequencies and so will add to the breadth of a vibrational band. However the fraction of molecules in excited electonic states will be small (as given by the Boltzmann distribution)I wonder whether MThompson was refering to KR's comment about "electron relaxation time" @72 which I must admit does seem out of place
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Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
MThompson - Those IR active vibrational quantum states are exactly what is involved in the greenhouse effect. [ For those not familar, nothing like the classics as a starter: Martin and Barker 1932, The Infrared Absorption Spectrum of Carbon Dioxide, is a good place to look ]
Those IR active vibrational states (which exclude lengthwise compression/expansion vibrations, as they don't change the electronic moment of the molecule and hence don't absorb/radiate) absorb/emit thermal range EM, with multiple wavelengths in each from different excitation states. These are further expanded by various spectral broadening effects (too many to briefly list).
Beyond that, I'm not certain what you are asking. Any IR active gas can and will act as a greenhouse gas, restricting radiation to space to an altitude where the remaining gases above have something less than a 50% chance (to a first approximation) of absorbing a particular upward photon - and due to the lapse rate, that altitude will be cooler than the surface atmosphere, meaning less energy radiated to space than would be the case in an atmosphere transparent to that wavelength. The overall effect is just a reduction in effective emissivity of the surface to space, and hence a higher temperature required to radiate the incoming energy back out, to maintain conservation of energy.
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jja at 06:30 AM on 29 August 2013How much will sea levels rise in the 21st Century?
(correction to 3. above)
Subsequently, I have a worst case scenario of temperatures 1.5C higher than the RCP 8.5 worst case scenarios for 2050 and 2.5C for 2100. This earlier increase in global surface temperatures causes an exponential increase in OHC deposition (and ice melt!), leading to a tripling of total cumulative OHC energy deposion and resultant thermal expansion by 2100. 3X RCP 8.5 worst case scenario is 1.23M. My RCP worst case scenario is closer to 10.0 (see below).
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jja at 06:26 AM on 29 August 2013How much will sea levels rise in the 21st Century?
Tom Curtis
(first let me thank you for your responses and for challenging my math skills as well as my understanding!)
1. Agreed, intentionally left out as original calculation involved water not ice, this value was assumed negligible and within error estimates.2. This is true, the rate of volume increase of water from 0C to 10C is less than from 10C to 20C. The amount of water volume compared to the total volume capacity of the world's oceans is also negligible so this value is insignificant (thought slightly negative)
3. B2 scenario is not part of the discussion we are looking at worst case (according to the scenarios I posted @ 16) A1F1 in AR4 is maximum of .41M thermal Expansion and AR5 is looking like RCP8.5 maximum of .38M of thermal expansion. AR5 RCP 8.5 expects a worst case scenario 2.5C warming by 2050 above 1880 levels and ~5C warming at 2100 above 1880 levels. In their scenarios they expect arctic sea ice to last to 2080. In my scenario, the arctic sea ice becomes summer-ice free by 2020 (june 21) and may 1 ice free by 2030. In RCP 8.5 this happens in 2080. Subsequently, I have a worst case scenario of temperatures 1.5C higher than the RCP 8.5 for 2050 and 2.5C for 2100. This earlier increase in global surface temperatures causes an exponential increase in OHC deposition (and ice melt!), leading to a tripling of total cumulative OHC energy deposion and resultant thermal expansion by 2100. 3X RCP 8.5 worst case scenario is 1.23M. My RCP worst case scenario is closer to 10.0 (see below).
4. This is the key. What percent of warming will contribute to ice melt and what will contribute to expansion. Fundamentally, the variance in projections of future TOA imbalance and cumulative energy deposition in the ecosphere between now and 2100 are the only key questions for sea level rise. If the cumulative energy deposition is much greater than projections then the energy balance can be 98% ocean and 2% else and still gain 5M of rise. The real issue is how much energy will be placed into the biosphere in the next 86 years.
5. Your estimate of TOA above implied a .44W/m^2, Hansen and Soto says it is probably closer to .63 +/- .15 but recent analysis by Trenberth would indicate an even greater value due to increased rates of OHC gains that were undervalued by Hansen and Soto. So a probable current TOA would be closer to .75 +/- .15 W/m^2.
your calculation stated that current values are .44 TOA and 1.63 RF increased linearly to an RCP 6.5 and 8.5 of 1.76 and 2.3 W/m^2 respectively. You state that a linear assumption is generous on your part. (conservatively assuming worst case).My scenario assumes a significantly decreased global albedo in 2020 and a much cloudier winter arctic than now. It also assumes an exponential decline in SOx emissions beginning in 2050. These two factors alone account for over 2W/m^2 increased RF by 2070. So the linear TOA imbalance is actually a much less conservative estimate. I also expected a significant increase in anthropogenic fraction for CO2 abundance as natural carbon sinks collapse. So my analysis is actually an RCP 10.0
But still, using your linear analysis and only having an RCP 8.5 but having current imbalance as .75 not .44 we get a final imbalance of 3.65 and a similar average energy deposition to my calculation at the bottom of @44.
If, however we use a more accurate and advanced rate of arctic ice melt, as well as the other assumptions I provided in @16 you will see that the non-linear increases in RF beginning in 2020 and peaking around 2050 will front-load the rates of energy depostion leading to a much higher value than those calculated even in @44. -
MThompson at 05:36 AM on 29 August 2013Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
@72
KR, Please help me understand which excited electronic states are playing a role in the greenhouse effect. I only familar with the IR vibrational quantum states.
Much appreciated.
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John Fasullo at 01:32 AM on 29 August 2013Fasullo (2013) Seeks Some Levelheadedness Regarding Sea Level Variability
Hi Chris,
Thanks for the feedback. Yes, the answer regarding other such drops in the historical record is complicated by the fact that our observations prior to GRACE and ARGO are incomplete, and prior to altimetry, are exceptionally so. We know that no comparable events occurred in the altimetry record. The gauge record of sea level is quite noisy on interannual time scales and so it is of limited use for identifying other events. There are comparable dips to that in 2010-11, but their credibility is highly questionable as they occur often and likely result from noise, not signal. And so what data to use?
If we were to argue that other events would require anomalous rainfall over Australia's interior basins comparable to that in 2010-11, then we could use the rainfall record to infer such sea level drops. In this case 1973-74 appears to be a comparable interval. Nonetheless, the assumption that the dips can only occur when Australian rainfall is high is questionable. Perhaps models will provide some perspective on this, and this is a possibility we are now exploring. Stay tuned!
In terms of 'dominant contributor', yes we did establish a % contribution. It varies somewhat depending on which GRACE product you use and at what time you evaluate the contribution. At the peak of the event, Australia made up about 50% of the storage +anomaly, with South America and North America, contributing about 30% and 20% respectively. But the anomalies in the Americas were relatively short lived whereas Australia's persisted for over a year. So at these longer time scales, Australia's influence was not only dominant, but solitary and unique.
Thanks for the informative/constructive feedback everyone! It is nice to read a blog where facts are the focus.
John
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dana1981 at 00:28 AM on 29 August 2013The Beginners Guide to Representative Concentration Pathways - Part 3
Note that we now have a 'Guide to RCPs' button in the left hand margin.
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The Skeptical Science temperature trend calculator
Nick Stokes - As per Foster and Rahmstorf 2011, the noise process is computed as ARMA(1, 1), not AR(n), as a simple autoregressive model turns out to underestimate autocorrelation in the temperature data. See Appendix 1.
This is discussed in the Trend Calculator overview and discussion.
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Nick Stokes at 23:18 PM on 28 August 2013The Skeptical Science temperature trend calculator
Kevin,
I've been puzzled about the 2σ confidence intervals on your calculator. They seem to have a high spread. I checked, for example, Hadcrut 4 from Jan 1980 to Jul 2013. The SkS calc says 1.56+-0.47 °C/Cen. But if I use the R call
arima(H,c(n,0,0),xreg=time(H))
with n=0,1,2 for AR(n), I get
1.56+-0.131, 1.55+-0.283, 1.53+-0.361
Your se seems higher than even AR(2). -
mitch at 21:31 PM on 28 August 2013The Beginners Guide to Representative Concentration Pathways - Part 3
Excellent summary--I was dreading the task of wading through the primary literature to put together a lecture on the RCP's. I assume that something is also included in the upcoming IPCC AR5 assessment report, but that is not yet available.
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ubrew12 at 19:52 PM on 28 August 20132013 SkS Weekly News Roundup #35A
The link to 'Kevin Trenberth's take on climate change' is not working for me.
I found a valid link at
http://minnesota.publicradio.org/features/npr.php?id=214198814
Moderator Response:[JH] Link fixed. Thanks for bringing this glitch to our attention.
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dvaytw at 18:41 PM on 28 August 2013Levitus et al. Find Global Warming Continues to Heat the Oceans
Got it guys, thanks!
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Andy Skuce at 15:39 PM on 28 August 2013Toward Improved Discussions of Methane & Climate
Michael Tobis rebuts Nafeez Ahmed:
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There's no empirical evidence
dvaytw - Point them to the RealClimate page The CO2 problem in 6 easy steps, which is perhaps the most succinct and numerically supported explanation I have come across.
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Tom Curtis at 14:24 PM on 28 August 2013How much will sea levels rise in the 21st Century?
jja @44 & 45:
1) You have forgotten to allow for the fact that ice is not as dense as water. You need to calculate the volume of water needed to raise sea level, convert that to mass as water, and then determine the volume of ice needed generate that mass of water. Doing so increases the energy needed per meter of sea level gained from ice melt to 120 Zettajoules.
2) You also neglect the fact that the ice, once melted, warms further till it matches the temperature of the surrounding water. That requires additional energy. Further, as the melting of ice results in greater gains of sea level in the tropics than at the poles, the temperature gain is substantial. Using a conservative estimate of 10 C temperature gain increases the energy required to 135 Zettajoules per meter of sea level gain.
3) You are not entitled to assume thermal expansion is a constant 1/3 of the sea level rise due to melting ice. The sea level gain is constant for a given level of OHC gain (assuming similar distributions of the heat). Ergo the sea level gain from thermal expansion for the B2 scenario is 0.12 - 0.28 meters. Allowing the upper limit, you need to find 4.72 meters of sea level gain from ice melt for a 5 meter sea level rise, not 3.33.
4) Currently, OHC accounts for about 95% of energy gains at the Earth's surface, leaving 5% for temperature gains in atmosphere and soil, and the melting of ice. For any 5 meter sea level gain, you need the amount of excess energy absorbed by the melting of ice to increase by a factor of 10 or more. That, however, will reduce the energy gained by OHC, reducing significantly the sea level rise by thermal expansion.
5) Using my estimate of TOA energy balance for RCP 8.5 at 43 above, you have approximately 1.45 W/m^2 TOA energy imbalance averaged over 87 years with which to melt your ice. That estimate assumes that the TOA energy imbalance increases linearly from its current value, which is a generous assumption for you. That gives you 2000 Zettajoules to play with to melt your ice. That means you require over 30% of energy from the TOA energy imbalance to go into melting ice to get your 5 meter sea level rise.
That is not impossible. Ice rafting of sufficient magnitude could channel much of the oceans gain in heat content into melting ice. However, nearly all your ice melt must come from such rafting, and there is no plausible mechanism to launch that much ice (approximatly equivalent to 2/3rds of all the ice in Greenland) onto the ocean in just 100 years.
Energy considerations cannot by themselve disprove the possibility of a 5 meter sea level rise, but they do show that you require a number of very implausible conditions to obtain it.
Regardless of these considerations, however, I remain convinced that the past is the guide to the future. Such massive rates of sea level rise greatly outstrip anything seen in transitions from glacial to interglacial states. That is despite the fact that those transitions involved far more ice available to melt, and at far lower latitudes. Absent detailed mechanisms explaining how a more rapid melt could occur, and specific evidence suggesting those mechanisms will come into play (neither of which exist for rates of increase of sea level greater than 2 meters per century), suggestions of such rapid melts must be considered as implausible, unscientific and needlessly alarmist.
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Levitus et al. Find Global Warming Continues to Heat the Oceans
dvaytw - The ocean skin layer, constrained by surface tension, is thicker than IR can penetrate and again with surface tension not convecting. Only thermal conduction can remove energy from deeper penetrating visible sunlight.
Downward IR warms the top of the skin layer, which decreases the thermal gradient across it, and less energy moves to the atmosphere.
Analogy: Take a metal rod, heat one end relative to the other. If the difference in temperature is, say, 10C, a certain amount of energy (heat) will flow from one end to another, at a rate determined by the thermal conductivity of the rod. If the difference between ends is only 5C (say with IR warming of the cool end), then less energy will be conducted through the rod, as the gradient is lower. That is equivalent to the thermal conduction of the ocean skin layer - a warmer surface means less energy flowing through the skin layer.
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DSL at 13:46 PM on 28 August 2013Andrew Dessler on Why It's Stupid not to Act on Climate Change
Yah, KR, I was hoping that pointing out Kampen's lack off engagement with the actual science would deter further garbage, but then the guy threw Chris Essex at me. My ensuing sigh nearly collapsed my lungs.
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jja at 12:14 PM on 28 August 2013How much will sea levels rise in the 21st Century?
correction to 105 cubic KM above - should be 360,000 cubic KM
with corrected math error the final energy deposition value per meter of sea level rise due to ice melt is ~110 ZJ per meter sea level rise (using above calc) or very close to MA Roger's 5 ZJ per 50mm rise @19.
so total energy deposition in ice to raise sea level by 3.333 is then calculated to be 367.4 ZJ, not the 107.13 quoted @43. -
jja at 11:12 AM on 28 August 2013How much will sea levels rise in the 21st Century?
if 105 cubic kilometers of ice melt has the capability to raise sea levels 1 meter (Lakes Agassiz and Ojibway melts 8,400 y.b.p.) and the enthalpy of fusion of 1 km cubed of ice is derived from the following:
105 km^3 = 1.05 X 10^17 cm^3
.9167 g/cm^3 of ice = 9.63 X 10^16 g of ice = 9.63 X 10^13 Kg of ice
enthalpy of fusion of ice = 334 KJ/Kg
9.63 X 10^13 Kg of ice * 334 Kj/Kg = 32.14 Zj per meter of sea level rise due to ice melt.Assume 1/3 of sea level rise is due to thermal expansion
3.3333 meters of sea level rise due to ice melt = 5 meters of total sea levle riseenergy deposition in landed ice = 32.14 ZJ * 3.3333 = 107.13 ZJ
so how does MA Roger get 100ZJ for only a 1M worth of sea level rise in @19?
and if the 107.13 X 10^21 Joules is all that is needed in total landed icemelt to raise sea levels by 5M (with 1.67M of rise due to thermal expansion) and the proportion of energy deposion is proportional to forcing and the final 2100 energy imbalance is 3.5 W/m^2.(I am sorry but your calculation does not include increased ice melt due to convective forces in a warmed world as well as albedo-induced localized warming in an ice free summer arctic-dicrectly increasing arctic amplification above current proportional rates -affecting greenland- your calculation also doesn't appreciate the effect of a slowing Thermohaline circulation on the western antactic shelf (localized warming-shelf undercut and the potential for a shelf collapse similar to the late E-Tr rise- but we will neglect that)
Then the average TOA between now and 2100 is about 2.125 W/m^2 which is equal to 1.08375 x 10^15 W (surface of earth = 5.1 X 10^14 m^2)
multiply by seconds
=3600 seconds/hour *8760 hours/year *86 years = 2.71 x 10^9 seconds
1.08375 X 10 ^ 15 W * 2.71 X 10^9 seconds = 2.93923 X 10^24 Joules = 2,939 ZJ total cumulative energy imbalance between now and 2100 assuming current TOA is .75 and 2100 TOA is 3.5 W/m^2any way you look at it, we cannot reasonably assume that sea levels will not rise by 5 meters under the scenarios that I presented in @ 16
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Andy Skuce at 11:10 AM on 28 August 2013Toward Improved Discussions of Methane & Climate
There is a rebuttal of the Whiteman et al paper by Nisbet et al here:
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davidnewell at 09:54 AM on 28 August 2013Andrew Dessler on Why It's Stupid not to Act on Climate Change
And if this URL reference doesn't scare the H--- out of you, then flash back to the early '60's, take two hits of the then legal Sandoz Labs LSD, and go see "A Clockwork Orange", or other thriller.
(No illegal action is hereby advocated.)
We are absolutely living in a horror story.
http://climatestate.com/2013/08/26/methane-release-from-the-east-siberian-arctic-shelf-and-the-potential-for-abrupt-climate-change/
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Rob Honeycutt at 06:38 AM on 28 August 2013Levitus et al. Find Global Warming Continues to Heat the Oceans
Dvawtw... You might also want to challenge your skeptic friends on their eyeball rolls related to models. (Sorry, I know it's off topic here. We can move elsewhere if there is more to discuss.) Your friends use models every day, even though they may not realize it. Models are not wrong. They're "boundary condition" experiments, like the model you use in your head (or planner) for planning your own activities through the day or week. They are not exact depictions of weather, which are "initial condition" experiments. Nor is your mental or planner model expected to exactly depict your activities.
More on that issue here.
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gws at 06:33 AM on 28 August 2013There's no empirical evidence
dvaytv @192
There is a logical argument that you can make:
Since all the physico-chemical properties of CO2 are well-established, and we can measure CO2's greenhouse (i.e. IR absorption) activity in the laboratory, and we have worked out both the math of its action in the atmosphere, and done the actual outgoing IR radiation reduction measurements -- spectrally resolved -- from space, we are very sure that CO2 is he most relevant greenhouse gas at this point in time. As we have, at the same time, overwhelming evidence that the increase in atmospheric CO2 since preindustrial times is entirely man-made, it follows logically (from these two lines of evidence) that man must be -- directly and indirectly -- 100% (with respect to CO2) responsible for the climate crisis that awaits us.
Ask them what contrary evidence they have.
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michael sweet at 05:34 AM on 28 August 2013Levitus et al. Find Global Warming Continues to Heat the Oceans
Dvawtw:
"There is a clear dependence of the skin temperature difference on the net infrared forcing." The Ocean surface emits IR radiation upward and absorbs IR from the atmosphere (backradiation). The temperature of the ocean surface depends on the difference between how much it emits and how much it absorbs (the net forcing).
"The net forcing is negative as the effective temperature of the clear and cloudy sky is less than the ocean skin temperature, and it approaches values closer to zero when the sky is cloudy. " The ocean is usually warmer than the atmosphere so the ocean loses energy to the atmosphere. On clear days the atmosphere is cooler and the ocean radiates energy into the atmosphere. On cloudy days the net forcing is small and the ocean loses little energy.
" This corresponds to increased greenhouse gas emission reaching the sea surface." On cloudy days more IR radiation from the atmosphere hits the ocean surface so the net forcing is small.
Is that any better?
The ocean is warmer than the atmosphere so the ocean emits IR to cool off. They measure a change in the ocean surface temperature that depends on the difference between how much the ocean emits upward and how much it abosrbs from Greenhouse gases emitting downward. When GHG increases, the downward emissions increase and that warms the ocean.
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dvaytw at 03:48 AM on 28 August 2013There's no empirical evidence
Hi fellas sorry for my usual blockhead question in this mostly quite technical discussion, but I'm wondering whether any/all of the empirical evidence outlined tells us about the amount of the warming for which we are responsible as well as simply identifying C02 as one of the culprits.
The reason I'm asking is because I've been arguing quite a bit with some guys who claim that they accept C02 is responsible for some warming, but the extent to which it is responsible can't be or at least hasn't been proven. I had a look at the "human vs. natural contribution" page, but it seems the studies there are mainly using models, which of course gets the inevitable eye-rolls from skeptics. Thanks in advance for any help with this blockhead question!
Moderator Response:[DB] In addition to the fine advice already rendered to you, this post is a treasure-trove of information:
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Tristan at 03:41 AM on 28 August 20132013 SkS Weekly Digest #33
There may be no debate under some definitions of the term, but Qld's Premier and its Minister for Environment seem to be getting their information from some source, and I wouldn't be surprised to learn that said source had some connection with Ms Codling and hubby. Not that I'm in any way insinuating that Campbell Newman would take scientific advice from billionaire mining magnates. Oh wait, yes I am!
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dvaytw at 03:15 AM on 28 August 2013Levitus et al. Find Global Warming Continues to Heat the Oceans
Hey guys I'm sorry to keep pushing here, but I'm trying to communicate these issues to people who don't understand the science well - which is difficult, when I don't either! I read the "Real Climate" article on GHG ocean heating, but this paragraph in particular I found hard (and obviously it is key):
"The figure below shows just the signal we are seeking. There is a clear dependence of the skin temperature difference on the net infrared forcing. The net forcing is negative as the effective temperature of the clear and cloudy sky is less than the ocean skin temperature, and it approaches values closer to zero when the sky is cloudy. This corresponds to increased greenhouse gas emission reaching the sea surface."
Can someone translate this into plainer English?
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hank at 02:41 AM on 28 August 2013A Looming Climate Shift: Will Ocean Heat Come Back to Haunt us?
Rob, I'm puzzled to find you've published exactly the same article in two places; this site and at
http://climatestate.com/2013/06/24/a-looming-climate-shift-will-ocean-heat-come-back-to-haunt-us/
Doesn't that divide the comments and keep people from seeing updates and related information? Or is there a reason for doing it this way?
Moderator Response:[JH] Rob Painting's article was posted on the website Climate State by Because all materials posted on Skeptical Science are published under a Creative Commons license, they may be reposted by others. Reposting allows more people to access an article than otherwise would be the case.
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MA Rodger at 22:43 PM on 27 August 2013Andrew Dessler on Why It's Stupid not to Act on Climate Change
Mark Bahner. You insist that your questioning requires answering on terms that you yourself set, yet your questioning revolves around a single statement made in the first 30 seconds of the Dessler video clip. If you find the answers provided in this thread less than what you wish for (I note you even list your own comments in this regard), do bear in mind that this questioning of yours is entirely off topic.
So here is a question for you to answer. Why don't you watch the video clip to the end? I ask that because I cannot see how somebody could have done so and then go on to assert that the statement "97% of scientists agree that global warming may be severe." is "unactionable;" Or indeed be so intent on demanding that a possibility ("may be severe" ) be converted into a quantified probability for a specific prediction of global climate, economy and society in the year 2100.
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Glenn Tamblyn at 22:26 PM on 27 August 2013Andrew Dessler on Why It's Stupid not to Act on Climate Change
Mark Bahner #23
You said 'the statement that AGW could cause "devastation on a similar scale to the impact of an asteroid (1-2 km in size) in the next 100 years" is patently ridiculous. ....
....And the effects are much more devastating for a 2-km asteroid. Estimates for that size asteroid are that more than 1 billion people would be killed.'
Estimates of yeild declines with temperature for a range of major grain crops report drops of 10% or so per degree C of temperature rise. Rice in many parts of the world is currently grown near the upper limits of its temperature range. Extreme weather events have a similar effect. 50% of the worlds food supply comes directly or indirectly from cereal crops.
Warmer water can hold less oxygen and reduces the carrying capacity of a patch of ocean, so warming of the ocean might reduce available fish stocks in the ocean. Ocean Acidification is already starting to impact the shell formation abilities of some small marine creatures at the base of the ocean food chain. The ocean supplies the primary source of protein for 1 Billion people.
As temperatures rise, growing season times are changing. This potentially changes the relationship between plants and their pollinators and predators.
For every 1 DegC of temperature rise it is estimated that wet bulb temperature, which governs how much an animal can cool itself through evaporation, rises by 66-75% of that. That animal might be a human being, who might be able to retreat into an air-conditioned space if they live in the western world. But it could also be a sheep, goat, cow, chicken etc that can't. With excessive heating heat stress sets in. Even if the animal doesn't die (some will) yields of essential food products (meat, milk, eggs, even blood) drop off.
If temperatures warm by several deg C latter this century, yield declines of all food production of 20% aren't unreasonable. Might be higher, might be lower. 20% seems rather middle of the road.
The world's population is currently around 7 Billion, trending towards 9-10 billion by mid century. And roughly speaking, current food supply is just managing to feed 7 billion. Yes, there are inefficiencies etc, but the food system we have now just manages to feed 7 billion. A 20% decline in food production, retaining current efficiencies would mean that we would only feed 5.6 billion.
And if our population has risen to 10 billion, that is a shortfall of 4.4 billion.
A middle-of-the-road estimate of how much all the effects of AGW might impact says tnat 4.4 billion people would starve. Not guaranteed. Might be less than that. Might be more.
But it doesn't look so patently ridiculous to me. Just because devastation happens in decades not days doesn't make it any less devastating.
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Chris8616 at 22:21 PM on 27 August 20132013 SkS Weekly Digest #34
Well, i was wondering since you write weakend considerably in light of the 1998 El Nino, but guessing otherwise it would have been even more pronounced is kind of dramatic thought. Thanks for your fast reply.
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grindupBaker at 19:27 PM on 27 August 2013Andrew Dessler on Why It's Stupid not to Act on Climate Change
@StealthAircraftSoftwareModeler #26 I was going to suggest you read SKS post 18 October 2011 by Rob Painting "How Increasing Carbon Dioxide Heats The Ocean" which includes "This heat cannot penetrate into the ocean itself, but it does warm the cool skin layer..." and refute it with science to make your point that LWR cannot heat the ocean and get some creds, but your comment is gone or I imagined it.
Moderator Response:[DB] Hot-linked referenced post.
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Rob Painting at 18:52 PM on 27 August 20132013 SkS Weekly Digest #34
Chris - Not sure what you mean, but I'll have a stab at it.
The 1997/1998 monster El Nino happened at a time when the wind-driven ocean circulation was spinning up - having spun down to a low point at around 1993. This spin up - a strengthening of the transport of warm surface water out of the tropics, and enhanced downward (Ekman) pumping in the subtropical ocean gyres - may have prevented the El Nino from being even more severe.
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grindupBaker at 18:41 PM on 27 August 20132013 SkS Weekly News Roundup #34B
@Shizel #1 chriskoz #6 My suggested recent opinion piece on the methane (above) was SkS Weekly News Roundup #32B 10 August 2013 by John Hartz "How Much Should You Worry About an Arctic Methane Bomb?" at "mother jones" site Thu Aug. 8, 2013.
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Chris8616 at 16:42 PM on 27 August 20132013 SkS Weekly Digest #34
Methane release from the East Siberian Arctic Shelf and the Potential for Abrupt Climate Change
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Chris8616 at 16:37 PM on 27 August 20132013 SkS Weekly Digest #34
Rob Painting, please clarify, explain: 1997-1998 El Niño the most recent event (exceptional warm year on record) when you write "the positive IPO phase weakened considerably and has been in the negative phase since the year 2000. In other words, La Niña been the dominant pattern of late."
Thanks.
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Tom Curtis at 16:27 PM on 27 August 2013Human CO2 is a tiny % of CO2 emissions
YubeDude @250, there is not one isotope, but two.
First, C14 is a radioactive isotope with a short half life (5730 years) as a result of which C14 is effectively undetectable in carbon sources more than 50 thousand years old (at which stage it has fallen to 0.2% of its original value. Because of that, fossil fuels are almost completely devoid of C14, as are volcanic emissions. The very rapid decline in C14 in the atmosphere since the onset of large scale combustion of fossil fuels shows that the source of the rapid rise in atmospheric CO2 is devoid of C14, and therefore does not come from recent vegetation, or the ocean.
Second is C13. C13 is a stable isotope of carbon, that does not increase or decrease in quantity with age. It is heavier than C12, however, as a result of which many plants will take up proportionally more CO2 with a C12 isotope than with a C13 isotope. The result is that carbon from organic matter, including fossilized organic matter in the form of fossil fuels, is deficient in C13. The decline in the C13/C12 ratio in the atmosphere since the large scale combustion of fossil fuels shows the resulting increase in atmospheric CO2 to come primarilly from an (originally) organic source, ie, from vegetation or from fossil fuels.
Taking the information from both isotopes, we see that the increased CO2 cannot come from modern vegetation because of the decreasing C14 concentration, and that it also cannot have come from volcanoes because the decreasing C13/C12 ratio. The only possible source that explains both trends is fossil fuels. Ergo, the increased CO2 concentration is a result of the combustion of fossil fuels.
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barry1487 at 16:10 PM on 27 August 2013The Beginners Guide to Representative Concentration Pathways - Part 2
Perhaps it will be covered in part 3 ("we will describe key metrics of the RCPs"), but is it possible to use the publicly available RCP model tools to model the tropical troposphere projections? I ask because Roy Spencer in his "Epic Fail" blogs posts is comparing tropical tropospheric temp observations to 73 RCP 8.5 models, and despite a few requests for him to spell out the parameters for the model runs he presents, he has not specified whether or not they are displaying surface temps or the hot spot zone.
Is it even possible for him to compare apples with apples in this case?
(I realize there are other issues with his posts, but that's the specific question I'm interested in)
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Andrew Dessler on Why It's Stupid not to Act on Climate Change
DSL - A fascinating article, if only because the 2011 publication has zero citations to date according to Google Scholar.
Background - Kampen claims all of the IPCC work, all of AGW, is based on correlational studies. That claim completely ignores satellite observations, spectroscopy in general, downwelling IR, isotope ratios, stratospheric cooling, faster nighttime warming, etc.. It is therefore utter nonsense.
This does raise an issue that I've seen from time to time on 'skeptic' discussions - that without control cases there is no way to tell what the single 'experiment' we are conducting on climate might be caused by. Absurd - we face the same issues in evolution, yet that is well accepted, and in gravity, in that there is no situation without gravitational influence.
Every day is another experiment, another relationship of forcings, temperatures, ice mass, etc. Time provides multiple replicates, with a huge amount of data available to discern between solar, GHG, aerosol, natural cycle, and even leprechaun influences on the climate.
Kampen also makes the unsupported claim that AGW is not falsifiable - again, untrue, as even just simple fingerprint tests such as the vertical atmospheric profile of warming or carbon isotope ratios could, if they gave certain results, falsify anthropogenic causes. But they don't - and in fact they reject other hypotheses such as solar variation.
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Kampen's paper is in essence a strawman argument - incorrectly describing anthropogenic global warming as correlative, as unfalsifiable, untestable, and arguing against that false depiction; when none of that is even remotely the case.
Promoting this kind of argument is (IMO) one of the identifying hallmarks of denial - when faced with an inability to raise solid disagreements with the science, create a strawman to argue against. It's simply a sign that the skeptic shouldn't be taken at all seriously.
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DSL at 13:58 PM on 27 August 2013Andrew Dessler on Why It's Stupid not to Act on Climate Change
Along these lines, someone just threw Jarl Kampen at me in a news comment stream.
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YubeDude at 13:48 PM on 27 August 2013Human CO2 is a tiny % of CO2 emissions
I am in search of an answer that I have not found in the comments tread or searching other references...relating to the isotope ratio signature that identifies ACO2 emissions. Is there also the signature of O18? The isotope signature that identifies Oxygen combustion either from natural events such as wild-fires or or anthropogenic events such as fuel combustion.
What I want to know is if there is any signature that has O18 along with a C13-C12 ratio that would show combustion of older Carbon sources. It would appear to this layman that a signature directly related to the combustion of older Carbon would surely be the smoking gun of anthropogenic activity; not that any logical suspision really exist but another brick in the wall surely would be welcome.
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Tom Curtis at 13:40 PM on 27 August 2013Andrew Dessler on Why It's Stupid not to Act on Climate Change
Mark Bahner @46, at the very start of the video, Andrew Dessler says:
"Should we listen to the 97% of scientists representing the mainstream view of climate science ..."
The view of the 97% is, therefore, clearly indicated as being the "mainstream view", which is the position represented by the IPCC. This has previously been indicated to you, and ignored by you. You may have formed the opinion that the IPCC AR4 is neither "incisive" nor "complete" enough to answer your questions, but that view must be considered ideosyncratic, and IMO is purely tactical. You may be prepared to say it, but it is for effect rather than to represent your beliefs.
What the IPCC AR4 doesn't to is suit your rhetorical ploy. It is not so stupid as to reduce "may" to a simple probability, because the probability of a particular severity of climate change depends essentially on the ongoing actions of humans as a result of explicit or implicit policies. It does indicate probabilities given an approximate implicit policy (ie, emissions following particular scenarios). That is, apparently, not incisive enough for you - which only shows that by incisive you mean "simplistic to the point of absurdity". Nor, obviously, does the AR4 quantify likely deaths because these again depend on actions taken, nor not taken to avoid those deaths. Again, to answer your questions in the framework you have chosen is to be simplistic to the point of stupidity.
You have not wanted a complex, and nuanced response to your questions because such a response does not give you a rhetorical hostage. That does not, however, mean that such a response has not been given. It has! You have simply chosen to ignore it.
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Mark Bahner at 13:05 PM on 27 August 2013Andrew Dessler on Why It's Stupid not to Act on Climate Change
Please demonstrate where "on this forum" (not just in the video) you have not been given your "incisive and complete answers".
My questions were:
1) What percentage probability did Andrew Dessler mean by the word "may" (e.g., <50%, <10%, <1%)?, and
2) What measurable parameters did he mean by the word "severe" (e.g., “global surface temperature change greater than ‘x’,” “sea level rise greater than ‘y’, ”reduction in life expectancy greater than ‘z’, etc.)?
Since not one comment has been from Andrew Dessler, or has quoted Andrew Dessler in responding to my questions, or has referred to any document from which Andrew Dessler was obviously getting his information, it's obvious that nowhere on this forum have I been given "incisive and complete answers" to my questions, since my questions were about what *Andrew Dessler meant* by the statement that 97% of scientists think that "climate change may be severe." If you'd like me to list each comment wherein I did *not* get "incisive and complete answers" to my questions, they are: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, and now 46.
P.S. Just FYI, it's much more common in science for people who make a claim like "you have received incisive and complete answers to your questions" to point to the specific place where those alleged "incisive and complete answers" exist, rather than to ask the questioner to point to all of the places where the alleged “incisive and complete answers” do *not* exist.
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michael sweet at 10:44 AM on 27 August 2013Climate sensitivity is low
Paul and MA,
This discussion seems to me to come down to how useful the IPCC terms are in a scientific paper. These terms have been discussed a lot beore and some people do not like them. On the other hand, people also did not like using numbers before the IPCC adopted the current terms. It seems to me extremely likely that the scientists reading the review paper are familiar with these terms, the paper is not intended for a lay audience. Most of the users here at SkS are also familiar with these terms. They are not perfect, but they are what we currently have. I imagine that if we switched to new terms someone else would complain. It is difficult to please everyone.
Perhaps you could write a new post that explains things better? Good explainations are always welcome.
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