Recent Comments

Prev  668  669  670  671  672  673  674  675  676  677  678  679  680  681  682  683  Next

Comments 33751 to 33800:

33751. John Hartz at 02:59 AM on 1 October 2014
       The Wall Street Journal downplays global warming risks once again
       

       Readers of this comment thread will also want to check out:

       The Climate Deniers’ Newest Argument, an Op-ed by Jeffrey Kluger posted by Time magazine yesterday, Sep 29, 2014.

       Like Dana,  Kruger critiques Koonin’s recent piece in the Wall Street Journal:

       The lede of Kluger’s op-ed:

       "It’s a lot easier to attack environmental scientists when you make up something they didn’t say—and then criticize them for saying it"

33752. WRyan at 02:46 AM on 1 October 2014
       How did the UK grid respond to losing a few nuclear reactors?
       

       I'm pretty sure that gas is a fossil fuel. So if wind power is displacing gas-fired power then wind power is "taking the place of fossil fuels."

       Figure 1 shows that the average value of wind-generated power was 2 GW higher from the Sunday night to the Wednesday night when compared with the pre-shutdown value. This is approximately equal to the reduction in nuclear power during this period. This is undoubtedly what the authors of the articles criticised in this piece were referring to when they wrote that an increase in wind power had replaced the lost nuclear generation. Thursday was the only day when the wind power value was lower than its pre-shutdown value.

33753. keithpickering at 02:32 AM on 1 October 2014
       How did the UK grid respond to losing a few nuclear reactors?
       

       The problem with wind (and solar, for that matter) has always been how to back it up when the wind dies. Currently that's almost entirely gas, making wind a crypto-fossil energy source. While it's true that wind-plus-gas is better than gas alone, it's also true that getting to zero fossil fuels on a wind-based system would be hugely expensive.

       The reason for that is that for geographically remote wind to back up local wind, distant regions must overbuild wind to meet their own demands AND potential demand from out-of-region. And each region must do this, to allow for the possibility that exports will be needed on windy days. But if those exports are not needed on windy days, those overbuilt wind turbines must then stand idle as the wind blows: a situation known as curtailment. Since curtailment reduces wind's capacity factor, it drives up the price of wind generated electricity. One recent study (Budischak et al. 2013) estimated that an all-renewable grid would nearly triple the price of electricity because of this issue. 

       We have reached the point where the only way to prevent a looming climate catastrophe is to deploy, deploy, deploy non-fossil energy sources as rapidly as possible. Given limited resources, the way to deploy the most non-fossil the fastest is to deploy the lowest-cost options. Those technologies are (1) shallow geothermal, where available; (2) hydro, where available; and (3) nuclear. Wind is almost as cheap as nuclear, but only as long as grid penetration remains low; once wind reaches the curtailment point (about 25% of total generation) its costs begin to escalate rapidly. 

       Jurisdictions that have already adopted this strategy have already decarbonized their grids: Sweden, Norway, France, Ontario. 

33754. MA Rodger at 23:41 PM on 30 September 2014
       It hasn't warmed since 1998
       

       Richard Hampton @286.

       I usually trot out the following levels of current annual ice loss - Arctic Ocean 300Gt, Greenland 450Gt, Antarctica 150Gt, Other 300Gt. Thise are far bigger numbers than last decade with today a total latent energy gain of 0.4 Zj pa. However that figure is a lot smaller than the extra annual increase in OHC which would be something like an extra 3Zj pa in just the measured bit of the oceans 0-2000m.

       So it is correct that more energy is being used melting ice but a whole lot more of the extra energy is ending up in the oceans. Further, if the atmosphere had been warmed significantly, most of that energy entering the oceans would be required to keep the atmosphere at the higher temperature and thus be radiating back into space.

33755. MA Rodger at 23:24 PM on 30 September 2014
       Your questions on climate sensitivity answered
       

       Tom Curtis @18.

       Thanks for pointing out my use of the wrong Gregory graph. It is as you say figure 1 that was used. I had assumed it was in figure 2 somewhere as I couldn't see how L&C14 obtained such low numbers from figure 1. But I had failed to account for the 60% adjustment used by L&C14.

       For the record repeating the exercise @17 with the figure 1 numbers yields ECS=2.13ºC.

33756. kmalpede at 22:38 PM on 30 September 2014
       People's Climate March NYC photos
       

       It was a great Day in NYC. and now what is next?www.theaterthreecollaborative.org/extreme-whether a play about the battle of Climate Scientists to speak truth to power. Oct. 2-Oct 26, Theater for the New City, NY, NY, with a Festival of Conscience including climate scientists: Jim Hansen, Jennifer Francis, Radley Horton,

33757. mancan18 at 09:08 AM on 30 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       I don't know how relevant this is and, although rhetorical, it is certainly not very scientific.

       However, I have read, with great interest, all the threads in relation to this article, particularly Tom Curtis who is always informative. With some of the threads here questioning the veracity of the 97% of scientists who agree that AGW is real, there is a line from the movie "Ronin" which might be relevant to those who wish to cast doubt. It is "When there is doubt there is no doubt". It seems to me that uncertainty is doubt. So does that mean that the 3% of scientists who are uncertain have doubt which means they have no doubt. But what does this mean about their doubt? Does this mean they have no doubt that increasing greenhouse gases from anthropogenic sources WILL warm the planet OR mean that they have no doubt that increasing greenhouse gases from anthropogenic sources WON'T warm the planet. Now the first proposition is believed by 97% of climate scientists and there is plenty of evidence to support their position. However, if those arguing uncertainty have no doubt about proposition two, i.e. increasing greenhouse gases from anthropogenic sources WON'T warm the planet, then they haven't proven their case, which most certainly, doesn't provide a sufficient reason to delay taking positive action to alleviate anthropogenic greenhouse gas emissions.

       Moderator Response:

       [RH] Please watch it with the all caps.

33758. Richard Hampton at 05:13 AM on 30 September 2014
       It hasn't warmed since 1998
       

        

       COMMENT TO SKEPTICALSCIENCE re PAUSE IN GLOBAL WARMING

        (snip)

       I wonder if the so-called pause in global warming as expressed by surface atmospheric temperature can be quite easily explained as follows? The measured net atmospheric temperature was increasing at an annual rate of about 0.025º C prior to the late 90's. It then leveled off rather abruptly and increased at a much slower pace. Climate change deniers have been celebrating this as evidence that global warming has stopped and there's nothing to worry about. But what really happened? If increased atmospheric CO₂ is trapping more energy, where is it going? What has changed? Andrew Shephard et al. in(Science, 2012, 338: 1183-1189 ), document a new phenomenon which began in the late 90's: significant net melting of arctic and antarctic land based ice. Greenland in particular and West Antarctica are losing about 400 gigatonnes per year (including allowances for increases of ice from increased snowfall in East Antarctica) as net ice melt. Prior to the late 90's there was no significant loss of land based ice mass. Their paper discusses the effect in terms of sea level rise (also measurable). But let's do the energy balance math. It appears that this recently arrived phenomenon of net ice melting coincides well with the abrupt change in the rate of atmospheric temperature increase. So, the energy required to melt 400 Gt of ice (its latent heat of fusion) is quite close to the amount of energy required to warm the earth's atmosphere by 0.025 º C. Wouldn’t such a newly arrived heat sink be taking up the so called missing energy? As has been widely reported, this “missing” energy is going into the oceans in the form of liquid water. So global warming has not paused at all! The earth is continuing to gain energy because of the increased energy absorption caused by the increased level of atmospheric CO₂. Ice melting is accelerating and the atmosphere is still showing signs of warming. Thus we could rightly assume that global warming and its effects on climate are continuing and even accelerating as more and more energy is embedded in our global environment as we burn our way into a high risk future. Short term greed, instant gratification, discounting the future, delusional economics, and denial of reality are the hallmarks of humanity's dis-function and abuse of our only home.

        

       Moderator Response:

       [RH] Snipped all caps (per policy) and resized font to standard size.

33759. Tom Curtis at 01:36 AM on 30 September 2014
       Your questions on climate sensitivity answered
       

       An ammendment to my post @18.  At ATTP, Paul S has pointed out an error I made in my use of the Ocean Uptake Efficiency.  Correcting for it, and allowing for non-ocean heat storage results in a slightly lower ECS than just making the error corrections already noted.  That would count as concurrence between the L&W estimate and an alternative reasonable approach.

33760. KR at 01:11 AM on 30 September 2014
       2014 SkS Weekly Digest #39
       

       This isn't the first time that a climate-related satirical cartoon has been criticized for not portraying every incidental part of the drawing in a photo-realistic manner. Such complaints are, properly speaking, whinging. IMO they are attempts to dismiss, denigrate, or distract from what said cartoon is actually saying. 

       Perhaps the cartoons are effectively making their points... hmm. 

33761. Tom Curtis at 00:39 AM on 30 September 2014
       2014 SkS Weekly Digest #39
       

       Russ R, perhaps you failed to notice the heavy satire.  Everybody knows that cartoons aren't science, and distort not only faces, profiles, submarine designs, and architecture but even science for humorous impact.  Somebody who thinks that noticing that fact informs others of something new, or is worthy of comment really needs to get a grip.

33762. Tom Curtis at 00:36 AM on 30 September 2014
       CO2 effect is saturated
       

       rational being @286, the increased warmth of the atmosphere from the increased greenhouse effect does in fact raise the tropopause, but it does so by increased convection due to the surface warming.  The change in radiative forcing would occur whether or not that happened.  I have explained the actual method of warming in greater detail and clarity than I can in a comment here.  I recommend you read it and comment further on that thread if you want to explore the issue in detail.

       I agree that averageing across the Earth's surface creates a multitude of problems.  They are not as large as often imagined, however, because at the effective altitude of radiation to space, temperatures are far more similar over a range of latitudes than they are at the surface (in part because of the higher tropopause in the tropics).  However, the alternative to using globally averaged values is (more or less) to develop a full scale AOGCM, which is a bit much for blog comments.  As it is, observations and AOGCM's show that globally averaged values give good back of the envelope estimates, though not accurate enough for detailed prediction (obviously).

33763. Russ R. at 00:35 AM on 30 September 2014
       2014 SkS Weekly Digest #39
       

       Tom Curtis,\

       Sticking to climate change related matters, you failed to notice the implied timeline... "a generation ago" implies < 50 years.

       Even the most dire predictions of sea level rise for the next 50 years are in the order of centimeters.

       Moderator Response:

       [JH] Your concerns have been duely noted.

33764. KR at 00:26 AM on 30 September 2014
       CO2 effect is saturated
       

       rational being - That's correct, increased GHGs (not just CO2) raise the tropopause, the slope of the lapse rate remains constant, and the entire atmosphere and surface are warmer as a result of increased effective radiating altitude. There's a fair bit of literature on that (see Google Scholar here), for example Santer et al 2003 states:

       Observations indicate that the height of the tropopause—the boundary between the stratosphere and troposphere—has increased by several hundred meters since 1979. Comparable increases are evident in climate model experiments. The latter show that human-induced changes in ozone and well-mixed greenhouse gases account for
       80% of the simulated rise in tropopause height over 1979 –1999. (emphasis added)

33765. Tom Curtis at 00:26 AM on 30 September 2014
       Your questions on climate sensitivity answered
       

       MA Rodger @17, my take was that they used the CCSM4 spun up from 850 AD as shown in figure 1 (red line) for pre-1950 ocean heat fluxes.  Certainly, based on a pixel count, it gives the same values over 1859-1882.  VarNVarN in figure 2c (solid blue line) is similar, but smoother and drops much lower around the turn of last century, which would allow much higher climate sensitivity.  I am not sure that woud be the case with the figure 1 values.

       For an alternate approach, I used the Ocean Uptake Efficiency from Gregory and Forster, along with HadCRUT4 to determine Q in the 19th century.  The result is a mean ECS of 1.98 K per doubling of CO2, inline with Otto et al 2012.  I discuss it in detail at ATTP.  I do not claim, of course, that that is the best approach, although I think it is significantly better than L&C's method as applied (ie, using a single run on a single ensemble member and an incorrect downscaling).  But the factor of 23 difference in the resulting estimated Q means L&C need to seriously justify their choice at a minimum, something they have not done.

33766. Tom Curtis at 00:08 AM on 30 September 2014
       2014 SkS Weekly Digest #39
       

       Russ R @2, you're right.  What a travesty.  Even worse:

       1. profiles of human heads look nothing like those shown;
       2. heads are not a third of body length as shown;
       3. the capitol building is shorter than the Washington Monument;
       4. fish don't blow bubbles;
       5. cavitation bubbles are not so persistent; and
       6. water currents do not show up as lines underwater.

       Clearly we need a new community standards board to eliminate all inaccuracies from cartoons.  The exageration of facts or features for humorous delivery is not to be tolerated.

33767. rational being at 00:05 AM on 30 September 2014
       CO2 effect is saturated
       

       Thank you Tom Curtis and KR for taking the time to reply.

       Are we saying that increasing upper atmosphere CO2 raises the altitude of the tropopause? And is the warming argument, then, that the temperature of the tropopause is fixed by the needs of radiative balance, so that a higher tropopause implies a warmer surface?

       The altitude of the tropopause varies over the globe from around 9km at the poles to almost double in the tropics. I suppose it is where convective heat transport gives way to radiation as the dominant mode. The details are complex enough that I am not sure simple averaging arguments work well.

33768. Russ R. at 23:54 PM on 29 September 2014
       2014 SkS Weekly Digest #39
       

       Re the toon:

       1. If all the ice melted, sea level would be 216 feet higher.
       2. The Washington monument is more than 555 feet tall.
33769. MA Rodger at 22:31 PM on 29 September 2014
       Your questions on climate sensitivity answered
       

       Tom Curtis @16.

       You say "their method of determining the Heat Content Flux for 1859-1882  ... is highly dubious." Coincidently for other reasons, I recently extracted the thermosteric SLR data from Gregory et al (2013) by scaling their Fig 2c. This is apparently what L&C2014 did to obtain thermoSLR data which they then used to infer OHC for years prior to the earliest OHC data. I must say, the resulting numbers do have a rather dubious feel. The Base Periods centred on 1870 & 1940 used by L&C2014 turn out to be the best choice possible for reducing Δ(F-Q) and thus for reducing ECS/TCR estimates. But I can now pick my own Base & End Periods and using the first half decade and last half dozen years of the Gregory et al thermoSLR data (this length of period to avoid volcanos) to infer Δ(F-Q), IPCC Appendix 2 for ΔF and HadCRUT(C&W) for temperature I get ECS=2.4ºC.

33770. Tom Curtis at 15:45 PM on 29 September 2014
       Your questions on climate sensitivity answered
       

       MA Rodger @12, even taken as a hypothetical excercise to determine the values of TCR and ECS using IPCC values, Lewis and Curry (hereafter L&C) is seriously flawed.  I explained part of the reasons in a comment at And Then There's Physics.  Further to that comment (quoted below), their method of determining the Heat Content Flux for 1859-1882 is not grounded in the IPCC, is highly dubious and likely further deflates their headline results.  In addition, more recent findings since the IPCC was published suggest a higher effective radiative forcing of aerosols is in order, which would increase the result still further.  So, as an attempt to determine ECS based on IPCC assumptions, the result is flawed - and even more flawed as an attempt to find the actual value of ECS.  (The determination of the value of the TCR is also flawed, but the problems are of little consequence given how close their value is to the IPCC values).

        

       "I downloaded the AR5 forcing data from Annexe 2, HadCRUT4 from the Hadley Center, Domingues et al OHC data from the CSIRO and Levitus et al forcing data from the NODC. I then proceeded to calculate ΔT, ΔF, and ΔQ from that data. Using C&L value for Q over the period 1859-1892(which I also dispute). The result was that L&C incorrectly estimated ΔT by 0.57% (small enough to be a rounding error), ΔF by 2.68%, and ΔQ by 17.03%. The later two are too large to be rounding errors. All errors favour lower values for TCR and ECS. Combined, the errors deflated TCR by 3.16% and ECS by 8.27%.

       The “error” in ΔT is just a rounding error as noted. That in ΔF may be due to an adjustment to the aerosol forcing. If so, it means Lewis and Curry are not, after all, trying to show what is obtained from the IPCC data, and need to independently justify their choices of data. If they were trying to show the results of the IPCC data, and also obtain the difference when the forcing data is modified as Lewis claims it ought, then they should have shown both.

       The difference in ΔQ is the most interesting. I obtained the most recent values by downloading the 0-2000 meter pentadal record, and using the difference between successive values to determine the difference between individual years six years apart. I then used the the 2005-2012 annual data as an anchor point from which annual values were reconstructed back to 1955. Comparison of rolling 5 year averages with the pentadal values showed a constant offset over the reconstructed period, which because constant has no effect on trends. I then deducted the 0-700 meter annual OHC, added in the Domingues 0-700 meter OHC and the Purkey and Johnson trend from 1992 (as per box 3.1) and dividing by 0.93 to account for the heat content of ice loss, into the ground and into the atmosphere.

       Interestingly, my figures and L&C’s figures agree within 1% if I neither add in the Purkey and Johnson trend for OHC below 2000 m, nor apply a modifier for non-ocean heat storage. This looks like a likely source for the error.

       Resolving the errors results in a mean TCR of 1.37 C, and a mean ECS of 1.79 C per doubling of CO2. These are still low values, but well within the IPCC range. Further, at this stage the errors amount to errors in arithmetic rather than errors in assumptions (of which I believe there are plenty)."

       (Bolding added to draw attention to key points.)

33771. Bob Loblaw at 11:57 AM on 29 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       Joe:

       In addition to the material provided by Tom, take a look at Hansen et al (1981) "Climate Impact of Increasing Atmospheric Carbon Dioxide", Science 213, 957-966. A copy is available on this NASA page.

       Figure 4 in that paper provides a result from a 1-d radiative-convective model, showing the first initial (instantaneous) response to doubling CO2, the changes a few months later, and the final changes many years later.

       • In the instantaneous case, increasing CO2 does cause a change in back radiation at the surface (+1.1 W/m²), but that is not what leads to warming. The key element is the change at the top of the atmosphere: a decrease of 2.4 W/m² (a reduction of 0.8 from the surface, and 1.6 from the atmosphere). There are also changes in the surface-->atmosphere convective fluxes. If there was no top-of-atmosphere (TOA) change, then we'd just see shifts within the system, not necessarily an overall warming.
       • After a few months, the atmosphere has had a chance to adjust, but the surface has not - the ocean heat capacity is the key here, At this point, the TOA imbalance is actually greater - a net change from 1xCO2 of -3.8 W/m².
       • Only after many years is the imbalance removed, after the entire system has time to warm. The net changes for the atmosphere, surface, and TOA (whole system) have re-equilibrated at 0.

       Koonin's mistake is to look at initial changes at the top of the atmosphere, and compare them to magnitudes at the surface. It's not the magnitudes that matter: it's the changes, and how the system reacts to counteract those changes (re-equilibrate).

       I know squat about plasma physics, so I can't come up with an analogy there. Perhaps a chemistry example? You have a chemical system that is in equilibrium, but it's highly active - mega reactions in both directions, at matching rates. You toss in a catalyst that slightly alters the reaction rate in one direction only. What happens?

       • It's not the change in reaction rate versus the original reaction rate that matters.
       • concentrations will change until the two rates balance again.
       • the new concentrations can only be predicted if you know how the two rates respond to the changing concentrations. If the rates change slowly with concentration, you need a large change. If the rates change rapidly, equilibrium is reached more quickly.

       [But I"m not a chemist, either, so this may be a crummy analogy.]

33772. chriskoz at 11:40 AM on 29 September 2014
       2014 SkS Weekly Digest #39
       

       Re the toon: a good reminder to anyone that "uniting against existential threat of ISIS" as the western coalition is doing right now is like treating the symptom rather than the cause. The cause is twofold:

       - the increasing impact of climate change related events, like drought in Syria as reportewd by Tom Friedman in Years of Living Dangerously,

       - the constqant military presense of western forces infringing the soveregnity of middle eastern countries (as you can read e.x. in other reports, i.e. "Hot Flat & Crowded" by the same Tom Friedman)

       Obviously the recent strikes on ISIS in Iraq only exacerbated the second cause while nothing is being done on the first cause. So while past & current symptoms (Saddam, Al-Qaeda, ISIS) may be extinguished, new symptoms will soon resurface.

33773. Tom Curtis at 11:12 AM on 29 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       JoeT @37, first, for ease of discussion, here is the IPCC Fig 2.11 (which is discussed in Chapter 2 of IPCC AR5 WG1:

       

       It is an update of previous images by Fasullo and Trenberth, inferior in not showing the size of the atmospheric window (40 W/m^2 in the latest Fasullo and Trenberth image), but superior in showing the 95% confidence interval in brackets.  Not including the data for the atmospheric window means the energy balance cannot be determined for the atmosphere, but only for the surface and the Top Of the Atmosphere (TOA).  The legend of the image informs us that:

       "Numbers state magnitudes of the individual energy fluxes in W m^–2, adjusted within their uncertainty ranges to close the energy budgets. Numbers in parentheses attached to the energy fluxes cover the range of values in line with observational constraints."

       (My emphasis)

       The important thing about figure 2.11 is that it only shows the energy balances.  It in no way shows the change in radiative forcing, and is in no way intended to show the greenhouse effect.  You can determine what is called the "total greenhouse effect" from it, that being the difference between the upward IR radiation at the surface and the upward IR radiation at the TOA.  That total effect, however, includes the effect of feedbacks that effect IR radiation (including WV, lapse rate, and cloud thermal feedbacks) as well as the direct effect of the total concentration of Well Mixed Greenhouse Gases, stratospheric water vapour, and ozone.

       To properly understand Koonin's error, it is helpfull to look at Fig 8.1 (from Chapter 8 of the WG1 report):

       

       "Figure 8.1 | Cartoon comparing (a) instantaneous RF, (b) RF, which allows stratospheric temperature to adjust, (c) flux change when the surface temperature is fixed over the whole Earth (a method of calculating ERF), (d) the ERF calculated allowing atmospheric and land temperature to adjust while ocean conditions are fixed and (e) the equilibrium response to the climate forcing agent. The methodology for calculation of each type of forcing is also outlined. DTo represents the land temperature response, while DTs is the full surface temperature response. (Updated from Hansen et al., 2005.)"

       The important thing here is to understand what is meant by radiative forcing, which is illustrated in Fig 8.1b.  It is the change in net upward radiation at the tropopause following a change in atmospheric composition or incoming radiation etc, after allowing the stratosphere to adjust temperature.  With a doubling of CO2 (approximately the situation Koonin considers), that change is 3.7 W/m^2.  To determine the percentage of that effect, you need to compare it to the net radiative forcing of relative to the situation with no greenhouse effect.  

       The total greenhouse effect is given by the difference between surface and TOA upward IR radiation, or 159 W/m^2.  However, 75% of that is due to clouds and water vapour, ie, due to feedbacks, and are not a "forcing".  The reason for that is that a change in those values will simply revert to equilibrium values in a short time.  So, the change in greenhouse forcing due to doubling CO2 is 3.7/(0.25*159), or 9.3%.  If the response of temperature to changes in forcing were linear (which they are not), that would result in an increase of temperature of 3.55 K before feedbacks (9.3% of 33K).

       Alternatively, we can see that increase is 1.6% of the TOA energy budget, leading to an linear 'expected' increase of 4.08 K; or a 0.9% of the net solar plus total greenhouse effect, leading to an linear 'expected' increase of  2.59 K.  

       Importantly, these are all TOA comparisons.  Because the radiative forcing is a TOA value (technically top of stratosphere, but the numerical difference with TOA is sufficiently small that it can be neglected), it can only meaningfully be compared to TOA values.  Koonin tries to compare a TOA value with a surface value, he is comparing apples to oranges, and demonstrating his complete failure to understand even basic theory of the science he criticizes.

       If Koonin wanted to make legitimate comparisons, he should really be making comparisons of temperature response.  The expected temperature response of doubling CO2 ignoring feedbacks is only 1.2C (+/-0.12 C).  That is only 0.4% of Global Mean Surface Temperature (GMST), but 3% of the temperature range consistent with the existence of human civilization.  Annual average temperatures below 0 C or above 40 C don't really concern us, because they are inconsistent with human flourishing.  It is the percentage change within that range that matters.  With feedbacks, that doubling pushes the response up to 6-12% of that temperature range.  With a GMST we currently have a small part of the Earth below that range (the poles), and no part of the Earth above it but nearly a third of the Earth is within 25% of the upper limit.  One doubling could push sizable portions of the Earth to the limit or beyond; while two doublings may make as much as a third of the Earth unsuitable for human civilization.  These are the percentages that matter.

       Moderator Response:

       [TD] The second figure in Tom's comment has gone missing (only the caption shows).  Will somebody please fix it?

33774. Tom Curtis at 08:55 AM on 29 September 2014
       Your questions on climate sensitivity answered
       

       For additional information, the often mentioned trillion tonnes of carbon limit on human emissions to avoid dangerous impacts of global warming amounts to a 540 ppmv limit.  That view, above all others, represents the scientific consensus on safe levels of emissions.  There are scientists who believe that even it overstates the necessary level of concern, but at least equally many who thinks it overstates the safe limits, including Hansen.  

       The later takes the view expressed by 350.org, ie, that 350 ppmv is the upper limit on safe greenhouse concentrations.  I have a problem with 350.org that they appear to over-egg the data.  Hansen, for example (and no doubt sincerely), considers the possibility of runaway global warming real, even though the science is very firmly against him on that point.

       My biggest problem with the 350.org point of view is a failure to take into account the fact that, given zero net human emissions, CO2 levels will fall substantially if slowly; and that the full impacts of ECS will occur slowly and on approximately the same timescale as the initial natural draw down of CO2.  These are very important facts, and make an otherwise impossible task plausible.  That is, there is an economic cost in reducing CO2 emissions at least in the short term, and reducing emissions to net negative values in the very short term as advocated by 350.org makes that economic cost sufficient that it could plausible cause as much damage as 550 or even 650 ppmv of CO2.  In constrast, limiting net emissions to 0.75 to 1 trillion tonnes (475-540 ppmv) in the short term will have an initial short term economic cost substantially less than (for example) the cold war.  That is, it is achievable while retaining the economic ability to achieve other major ends.  

       Developing the technology to limit CO2 emissions by that amount will also develop the technology to go the further and necessary step to achieve net zero anthropogenic emissions.  In particular, zero gross anthropogenic emissions will be impossible to achieve for a variety of reasons, and gross emissions above 5% of current emissions may result in either no natural draw down, or a long term slow build up of CO2 concentration.  Therefore, as with 350.org, I agree that we will need to develop a cost effective technology for carbon sequestration.  I disagree about the scale to which that is necessary, and the time period in which it is necessary.  

       (Apologies to the moderators for the extensive off topic post.)

33775. sidd at 08:54 AM on 29 September 2014
       The Wall Street Journal downplays global warming risks once again
       Koonin is doing exactly what he has been commissioned to do, influence the APS/AIP climate change statement. I urge those of you who are APS or AIP members to write (paper/snailmail is much better than email) to pointing out his underhanded elisions and demanding a strong statement on climate change. The op ed is directed toward that smallish fraction of physicists who yet engage in denial. As for the rest, he is at a disadvantage, they are scientifically literate, can calculate and look up citations ...

       Note though, there is actually mention of a revenue neutral tax on fossil carbon. That, coupled with the Goldman Sachs downgrade of Peabody Coal indicates to me that the oligarchs are looking for an exit.

33776. Tom Curtis at 08:29 AM on 29 September 2014
       Your questions on climate sensitivity answered
       

       ranyl @13, it would be helpfull to myself, and presumably other readers if you distinguish quotation from your own words.  At a minimum, you should use quotation marks (on your keyboard next to the enter key).  It would also be helpful if you used the indent function from the wysiwyg panel in the comments screen, indicated by the quotation mark signal.

       Trivial points aside, it is very easy to get a long list of papers which indicate models may (there is disagreement on the point among relevant scientists) overestimate CO2 drawdown (or climate sensitivity).  It is equally easy to get long lists of papers which indicate models may overestimate the same.  Climate change deniers continually refer to the later and ignore the former, in a process that is called pseudoscience.  It is no more scientific to continually refer to the former and ignore the later.  The climate scientists who actually device the models, such as David Archer, keep track of both; and revise the models on the basis of the balance of evidence.

       So:

       • While you can list a series of reasons to think the models underestimate draw down, it has recently been shown that volcanic emissions are significantly larger than previously thought, which implies a larger draw down rate, and hence that models underestimate the draw down.
       • The models in question have with reasonable accuracy retrodicted the Earth's carbon budget over the last 600,000 years.  While they are likely to be wrong in detail (as with all models), they are therefore unlikely to be wrong about the basic picture.
       • The higher temperatures and sea levels in the pliocene where in a near full equilbrium condition.  That is, they were achieved as the Earth achieved its Earth System Climate Sensitivity, which is noticably higher than the Equilibrium Climate Sensitivity or the more relevant (over the coming two centuries) Transient Climate Response.
       • Finally, anybody who knows me knows I am not sanguine about about even 500 ppmv, let along 650.  As a matter of urgency we need to stop net anthropogenic emissions before atmospheric CO2 tops 450 ppmv.  Not, however, due to some panicked forecasts about the effect of a current 400 ppmv 500 plus years down the track.
33777. ranyl at 07:23 AM on 29 September 2014
       Your questions on climate sensitivity answered
       

       ranyl & Rob P @8, with a slug of CO2 of a trillion tonnes or more, approximately 25% remains in the atmosphere in the long term. About 50% has human emissions have already been drawn down, so another 50% remains to be drawn down. That means to get a long term 400 ppmv CO2 concentration, in the short term CO2 concentrations need to rise to 620 ppmv. For 460 ppmv CO2e, you need 640 ppmv of CO2 (as other WMGHG decay in the short term). The upshot is that long term concentrations of 400 ppmv plus, along with the effects of such concentrations evident from the paleo record, are likely long term consequences of BAU (RCP 8.5 or even RCP 6) scenarios. They are still very avoidable, however, if we get serious attempts to mitigate climate change.

       Sorry Tom that is using models with many CO2 feedbacks not included, presuming a strogner fertilization effect than being seen, not including forest fire feedbacks, and several others despite the complexity of the models. And don't forget the widespread fertilization effect of nitrogen fertilisers, that has been more than enough to offset all the NO2 emissions from them, stop using the industrial fertilizers as is necesary for biodiversities sake and well that fertilizer effects goes. And si has been shown that ecosystem disrupton releases carbon (not included in those optimistic carbon withdrawal nodels),  adn extrem weather event sand increased erosion is releasign soil carbon, and then there si the frozen sea bed stoes of permafrost of siberia that are releases stuff also not included.

       We are already committed to be above 400ppm (and think 470ppn CO2e) for at the very best least another 200 years or so, so that is at least 80% of the warming of full equilibrium.

       Stiff the roses.

       350-400ppm it was 3-5C hotter and that was not including the extra heat recetnyl found in the western pacific recently reported, the WPAC was 3C hotter than thought and that is a reasonable chunk of ocean to increase, and thus 5C is the much more likely.

       There is no more room for any more carbon emissions, yet we are going to have lots more for nothing stops overnight.

       Now I get all the papers and many more to prove these points.

       Including several recent papers that match climate models to reality in temr so fo wate vapour and cloud fomrations when only the models with a climate sensitivity of 3C or above do the trick,  and it is more likel yto be 4C as many are now realising.

       We have a huge carbon debt not a budget.

       But anyway apparently WWW3 has kicked off in papal terms so that wil a whole load carbon emssions and habitat destruction with millions of people sufferign on top, so let su be sure 400ppm will soon be a distant target everyone wishes we could back to, but gettign any CO2 out the atmosphere any time soon will a transformation of everything to acheive.

       And how much carbon extra is it going to take to actual make all the new power generation, electric cars, etc, and just how toxic are batteries and the like?

       Oh I know lets pretend we put another 1/3 again of CO2 into the atmosphere because some computer models (that have underestimated lots so far (e.g. sea ice arctic), give a 2/3 chance of avoiding 2C by 2100, or to put it another way lets play russian roulette with 2 bullets in the 6 carousel with the future of humanity?

       Now what is the carbon budget that gives a 95% chance of avoiding 2C when the CS is 4C?

33778. JoeT at 05:06 AM on 29 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       Tom or Bob,

       I think it's important for physicists such as myself (I'm a plasma physicist), who are essentially ignorant of climate science (but I'm trying to learn!) understand clearly what Koonin is saying. One more question if I may, just to make sure I have it right. The shocking thing to me from Figure 2.11 of the IPCC report is how huge the back radiation is, 342 w/m2 compared to the solar absorbed at the surface, 161 w/m2.  So if I look at a rough energy balance, then there is 159 w/m2 difference between the radiation output at the surface and that at the TOA. Now to get to 342, I need to add 84 for evaporation, 20 for sensible heat and 79 for solar that is absorbed in the atmosphere. That comes to 342 exactly. So, just to be pedantic about all this, the mistake Koonin is making is that he is including evaporation, sensible heat and solar as contributions to the greenhouse effect, rather than just the 159 w/m2. Am I saying that correctly? TIA.

33779. MA Rodger at 19:06 PM on 28 September 2014
       Your questions on climate sensitivity answered
       

       Lewis & Curry (2014) is pretty much what you'd expect from the title 'The implications for climate sensitivity of AR5 forcing and heat uptake estimates' and from its authors - a bean-counter meets a quasi-holistic climatologist. The thrust of the study is to take the numbers from AR5 WG1 Appendix2 and shove the implications of them back at the IPCC. This is easily done but there is quite a bit of cheese-paring required to get the desired result. For instance, note how the 'headline' 1859-2011 result when compared with Otto et al inc. Lewis (2013) loses 5% of the ∆T and gains 25% of the ∆(F-Q).

       And choosing a different temperature record than HadCRUT4 would gain 5-10% more ∆T. The comparing of peak temperatures from late-1800s & mid-1900s is potentially questionable unless you are signed up to a big constant-amplitude multi-decadal oscillation. There is certainly room for significantly higher sensitivity by taking different time periods if the Appendix 2 forcings are taken at face value (which is what the study is about). And as most of the warming has occurred recently, slow feedbacks will not have had time to act for 'most of the warming'. And the one natural wobbler of temperature that is beyond doubt, ENSO, is an unknown for the post-1850 period. ENSO could have elevated the 'headline' base temperatures just as it has mainly depressed the 'headline' end period. That could easily have clipped 10% off the ∆T used bt Lewis & Curry. (I note the MacDonald & Case (2005) PDO reconstruction (wiki-graph) looks a bit positive for 1859-82 suggesting ENSO will indeed have been warming.)

       So the headline low ECS provided by Lewis & Curry (2014) is at best controversial.

       And do note, if it is as Lewis & Curry suggest, it only works if we are now about to experience a repeat of the cooling cycle seen twice before over the last 160 years. So hold onto your hats. The Kara Sea will melt away (or is it 'ice over'?) plunging the whole Northern Hemisphere into two decades of cooling and priming a negative AMO ready for another round of Wyatt's Stadium Wave. This I will enjoy seeing.

33780. Rob Painting at 15:06 PM on 28 September 2014
       Your questions on climate sensitivity answered
       

       Tom @ 9 -  True, it depends how things pan out in the real world. If, for instance, carbon fertilisation of the atmosphere does indeed cause the stupendous growth of land-based plants, as the carbon cycle models predict, much of the excess carbon dioxide will be drawn down. The evidence for this is pretty equivocal so far.

       Also, once the ice sheets are committed to collapse, there's no turning back. If we haven't passed that point, and humanity were to get its act together, the collapse of the ice sheets may be averted. Trouble is that empty assurances are all we have so far. Fossil fuel emissions keep climbing, and will continue to do so for the foreseeable future.

       As you may have figured out, averting dramatic future sea level rise is not something I'm very optimistic about. 

33781. denisaf at 13:35 PM on 28 September 2014
       Your questions on climate sensitivity answered
       

       Sunlight is energy input that is absorbed in heating up the atmosphere and the oceans as well driving operations on the land. Energy is output by radiating out into space. The energy input and output had been roughly in balance for eons, so enabling the biological operations that organisms were dependent on. Then the emissions from fossil fuel usage rapidly upset that balance so heat has accumulated in the atmosphere, oceans and land. The emissions have effectively placed a blanket around the globe, so causing the warming. Cutting back the rate of emissions will do no more that slow down the heating. The energy input and output balance has been irrevocably degraded by the operations of industry. Natural forces will very slowly restore this balance after the demise of industrialed civilization.

33782. Tom Curtis at 12:45 PM on 28 September 2014
       Your questions on climate sensitivity answered
       

       ranyl & Rob P @8, with a slug of CO2 of a trillion tonnes or more, approximately 25% remains in the atmosphere in the long term.  About 50% has human emissions have already been drawn down, so another 50% remains to be drawn down.  That means to get a long term 400 ppmv CO2 concentration, in the short term CO2 concentrations need to rise to 620 ppmv.  For 460 ppmv CO2e, you need 640 ppmv of CO2 (as other WMGHG decay in the short term).  The upshot is that long term concentrations of 400 ppmv plus, along with the effects of such concentrations evident from the paleo record, are likely long term consequences of BAU (RCP 8.5 or even RCP 6) scenarios.  They are still very avoidable, however, if we get serious attempts to mitigate climate change.

33783. ranyl at 08:39 AM on 28 September 2014
       Your questions on climate sensitivity answered
       

       How hot was the earth the last CO2 was 400ppm?

       Or should we say 460ppm Co2e?

       And how high were sea levels?

       Moderator Response:

       [Rob P] - Based on the relationship between atmospheric CO₂ and sea level over the last 40 million years, we are likely committed to 24 metres (+7/-15 metres at 68% confidence) of future sea level rise.

       That seems to be supported by recent observations from the Antarctic showing that the West Antarctic ice sheet, and perhaps coastal sectors of the East Antarctic ice sheet, are beyond the point of no return. It will likely play out over millennia, but over a metre of sea level rise this century will cause widespread disruption and be extraordinarily expensive to deal with.

33784. Bob Loblaw at 07:40 AM on 28 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       Tom:

       I agree that doing it right has been around a lot longer than 1979, and misunderstandings also go back further. The reason I picked Newell and Dopplick as an example was two-fold:

       • I knew of the study (and the comment/reply), having been exposed to it (and why it was wrong) as part of my graduate studies in the mid-1980s (i.e.. 30 years ago);
       • it was an example of the sort of mis-understanding that Koonin is making - but an example that appears in the proper scientific literature, underwent peer review, was properly critiqued in the same journal ("hey, you made some mistakes"), and where it received a proper reaction from the original authors ("oops"). Journal-published comments on bad papers are so rare these days that it is useful to have examples where they exist.

       The second point is germain to the fact that Koonin:

       • is making his points in non-peer-reviewed slop-eds and opinion papers;
       • is making mistakes that were somewhat permissible in the scientific literature 35 years ago (J Applied Meteo is a generally excellent journal);
       • is making mistakes that he has no excuse (other than willful ignorance) for making in 2014.

       If Newell and Dopplick tried to publish a similar paper today, in a respectable journal (not something like E&E or one of the off-topic or vanity press labels the denial indistry is fond of), it would likely not get published at all. Knowledgable reviewers would notice the mistakes immediately.

        

       Joe:

       As I knew it was Robert Watts (respected scientist), having read the comment decades before Anthony's blog was a gleam in a denialist's eye, it didn't even occur to me that someone might wonder if it involved Anthony. Thanks for a good laugh!

33785. John Hartz at 03:05 AM on 28 September 2014
       Your questions on climate sensitivity answered
       

       Speaking of ATTP (And Then There's Physics)...

       In his article, Study lowers range for future global warming, but does it matter? (Capital Weather Gang, Washington Post, Sep 26, 2014), Jason Samenow references and links to  ATTP's post, Lewis and Curry. 

       Here's what Samenow has to say:

       "The blog And Then There’s Physics lists several reasons why Lewis and Curry’s estimate could be too low, including not fully accounting for the transfer of heat between the ocean and atmosphere.

       "It further cautions one must use be careful in leaping to conclusions from the results of a single study. Computer modeling studies generally estimate higher values for ECS, as do some studies based on paleoclimate data."

33786. Tom Curtis at 03:02 AM on 28 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       Bob Loblaw @33, Koonin is even more out of date than that.  Arrhenius appears to have calculated the greenhouse effect based on back radiation, and the idea of a saturated CO2 effect due to Angstrom (1901) can almost make sense on that basis.  Callander in the 1940s, however, showed the greenhouse effect to have not been saturated using more detailed data on absorption at different wavelengths.  However, the model of the greenhouse effect used might still be considered a back radiation model.  That changes with Manabe and Wetherald (1967) which explicitly incorporates convection into the model, and explicitly models radation balance at the TOA.  Therefore, by 1967 at the latest, Koonin's theory was falsified and out of date.   He is ignoring 46 years of science he finds inconvenient, including, as you point out, a direct refutation of his theory.   

33787. JoeT at 01:35 AM on 28 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       Thanks Bob for the additional comments. I have to admit that I went to the Watts reference first, but was reassured that it was a Robert from Tulane, not an Anthony from nowhere. The articles were actually very informative, so thanks for pointing them out. As a member of the American Physical Society myself, it concerns me greatly that Koonin is (or was?) the chair of the APS committee tasked with rewriting the orgranization's position on climate change. It's the reason I was particularly interested in understanding his article.

33788. Bob Loblaw at 01:06 AM on 28 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       JoeT's comment @38 quotes Koonin, and provides a link to the source. As soon as I read JoeT's comment and followed it to the original, I realized that Koonin was making a rookie mistake. Tom and Joe have provided good discussion; I'd just like to point out the following, which agrres with Tom and Joe:

       • Koonin compares radiative changes due to CO2 increases with surface energy balances. This is wrong.
       • What happens at the surface is highly complex, involved convective as well as radiative energy exchanges.
       • The role that increasing CO2 plays in climate is best represented by the changes in the top-of-atmosphere radiative exchange.

       Koonin is not the first to make this mistake. For example, in 1979, Newell and Dopplick published a paper reporting a much lower CO2 sensitivity than other papers had been suggesting. In 1980, Watts published a comment, pointing out the errors (including the mistake of looking at surface energy balances). Knewell and Dopplick responded, acknowledging errors. At one point, they even say "These criticisms are accepted. The situation appears to be much more complicated that [sic] we realized two years ago." This is how science works: publish, review, accept errors and move on.

       Koonin is at leat 35 years behind the times in the mistakes that he is making. I wonder how long it will take for him to be scientific and learn from his mistakes? He can clearly be scientific on other topics, but on climate change he's a pseudo-skeptic or dismissive.

33789. Doug Bostrom at 16:58 PM on 27 September 2014
       97 Hours of Consensus reaches millions
       

       Re Wol's offering, it's sad for all of us how a bag of hammers always sees nails, always drops the same way, doesn't seem capable of learning anything useful to itself or the world at large.

       Critiques of the Cook et al paper generally produce a familiar, dull clank and thud ending their fall, following as they do a limited selection of  trajectories with which we're all dismally familiar after witnessing decades of the same behavior regarding climate science itself.

       Failing to actually read the research in question before blurting an opinion is basic bag of hammers instinct. 

33790. Ken Rice at 16:05 PM on 27 September 2014
       Your questions on climate sensitivity answered
       

       Although Tom has already pointed this out, since it was attributed to me, I will add that I didn't ever say that the method doesn't take the role of the oceans into account.  In determining the ECS it does indeed include the change in system heat uptake rate, which is dominated by energy going into the oceans.  As others have mentioned there are issues with how they've determined their system heat uptakes rates, but it isn't corret that the method doesn't consider the oceans at all.

33791. Wol at 09:38 AM on 27 September 2014
       97 Hours of Consensus reaches millions
       

       I'm sure you have read this: 

       http://data.parliament.uk/writtenevidence/WrittenEvidence.svc/EvidenceHtml/4191

       Comments?

       Moderator Response:

       [Rob P] - Yup, he doesn't even appear to have read our peer-reviewed paper Cook et al (2013). I find reading generally helps to clear up misunderstandings. Cook (2013) states:

       "In a second phase of this study, we invited authors to rate their own papers. Compared to abstract ratings, a smaller percentage of self-rated papers expressed no position on AGW (35.5%). Among self-rated papers expressing a position on AGW, 97.2% endorsed the consensus."

       Guenier claims:"......a subjective interpretation, as authors were not asked about their view"

       Probably lawyer-speak, but it insinuates that our rating process was simply our opinion. The authors of the respective papers are more likely than anyone else to know what their research had to say about global warming. Our abstract rating process had the scientific consensus at 97.1% whereas the author self-ratings were slightly higher at 97.2%.

       The simple fact is that the world is warming and changing pretty much as expected. The scientific literature just reflects the overwhelming nature of the evidence. That some people reject science is hardly a novel revelation. 

       Oh, and please note that link only comments are against SkS policy and will be deleted in future. You need to provide some discussion to demonstrate you're not just link-spamming a thread.

33792. Tom Curtis at 08:25 AM on 27 September 2014
       Your questions on climate sensitivity answered
       

       Christian, hi.

       My original version of my comment mentioned, and linked to your comment at ATTP.  Unfortunately it was lost and the repeat was much shortened.

33793. Christian11155 at 08:12 AM on 27 September 2014
       Your questions on climate sensitivity answered
       

       Hi Tom,

       You rigth, that was what figured out in "And Then There's Physics" Blog. In Fact, L&C used heat-uptake but their value is unable to explain real sea level rise in their final periode and this would imply, that heat uptake from other sources as ocean heat uptake.

       Because they ignored other sources, their dQ (Heat-Uptake) ins biased to low.

       And that is what ive written in "And Then There's Physics" at September 26, 2014 at 2:37 pm

33794. Tom Curtis at 07:47 AM on 27 September 2014
       Your questions on climate sensitivity answered
       

       Roz Pidcock in the OP writes:

       "One criticism of the energy budget model approach that lies behind these kind of studies is that it doesn't take into account the role of the oceans in taking up excess heat."

       In fact the formula used by Lewis and Curry is ECS = change in temperature divided by (change in forcing minus change of heat flux into the oceans).  Therefore they very explicitly take into account the role of oceans in taking up excess heat.  And Then There's Physics never said otherwise.  There are very valid criticisms (IMO) of their methods of taking OHC flux into account, but not that they ignored it all together.

33795. Tom Curtis at 07:21 AM on 27 September 2014
       Your questions on climate sensitivity answered
       

       Russ R @1:

       1) You say "all estimates derived from recent temperature observations, which are consistently lower than those derived from paleo proxy data or computer models" as if it were actually true.  In fact, many estimates based on the instrumental record are as high as or higher than those from the paleo record and computer models.  On average, those from the instrumental record are slightly lower.  Perhaps more germain, the estimates from the instrumental record that you read are biased low due to your sources of information.  But neither of these facts make your assertion true.

       

       2)  You are correct that climate sensitivity is "not a thing" (though neither is g).  Major changes in continental positions, changes in dominant ocean currents, changes in vegetation and rainfall patterns, and changes in GMST will all effect the the value of the climate sensitivity.  Therefore Paleo Climate estimates primarilly provide a sanity range.

       However, you do not think the consequences of that through.

       What it means is that the purportedly low climate sensitivity over the twentieth century is no gauranttee of a continuing low sensitivity into the future.  As global temperatures rise it becomes likely that the low climate sensitivity of recent times (if it is a fact) will revert to the higher non-glacial climate sensitivity from paleodata (ie, regress towards the mean) so that the final impact of anthropogenic forcings will be determined by that higher climate sensitivity than our purported valley.

       You argue against that based on an expected reduction in ice albedo feedback as the planet warms.  That expectation is correct, but there is also an expected increase in the strength of the water vapour feedback as the planet warms due to the Clasius-clapeyron relationship.  The ice albedo feedback is currently near a minimum and is very low compared to that during glacials (for example).  Any major warming, therefore, is likely to result in the increase in strength of the water vapour feedback dominating over the decrease in strength of the ice albedo feedback.

       You also appeal to uncertainty.  In decision making under risk, uncertainty is not your friend.  If your playing Russian Roulette, the game is not made safer if before each go, the gun is loaded with the result of the roll of a six sided die minus 2 cartridges.  On the contrary, the uncertainty makes the game even more foolhardy.  In this case, uncertainty may mean that nailing down the current ECS at a nice midrange 2.5 C does not gauranttee us that it will not have pushed out to 4 C by the end of this century.

       3)  Despite the increase in sea ice in the Antarctic, the decrease in sea ice in the Arctic is larger in magnitude, and the decrease in winter snowfall in the northern hemisphere is larger still.  The net effect is that most models underestimate the ice/snow albedo feedback rather than the reverse.

33796. JoeT at 07:00 AM on 27 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       Tom, I was working on my own post and didn't see yours until I submitted it. I'm glad to see we both have the same conclusion.

33797. JoeT at 06:57 AM on 27 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       Now that I went over Koonin's references, I think Tom's #8 is appropriate — the one he withdrew -— with bits of #9 thrown in as well. Post #8 is correct because Koonin really is looking at the downward radiation as the greenhouse effect, not the difference between the upward surface radiation and that at the top of the atmosphere. That's the difference between 342 w/m2from IPCC figure 2.11 and (398 - 239) = 159 w/m2. Then from SPM.5 (summary for policymakers) he takes the total anthropogenic forcing since 1750 of 2.29 w/m2. Then he does a net trick — he divides the 2.3 by 503 to get 0.0046, which indeed is less than 0.5% !!! That is he adds the incorrect 342 to the incoming solar radiation of 161 w/m2. Otherwise that number should really be 2.3/159 = 1.5%.

       
       Then he says assume by 2050 CO2 rises to 550 ppm. Then the increase in the forcing is 5.35 ln(550/400) = 1.7 w/m2. Add that to 2.3 and you get 4.0 w/m2 (Koonin says 3.9). Now 4/503 = 0.8%, so to get the 1-2% that he says in the WSJ, he must have taken 4/342 = 1.2%.

       
       Nowhere does he talk about sensitivity however and actual temperature change.

33798. Tom Curtis at 06:46 AM on 27 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       JoeT @28, thankyou for the sleuthing.  Given the footnote it becomes sadly apparent that I was right the first time.  I need to reinstate my comment @8, which discusses this misunderstanding, and withdraw my comment @9 (which while technically accurate, does not discuss Koonin's opinion).

       So specifically:

       1)  Koonin misrepresents the greenhouse effect as simply a function of backradiation.  That interpretation of the greenhouse is false, and has been known to be false for well over three quarters of a century.  In scientific terms, it is like criticizing the planning of the apollo missions because they will not work based on Aristotelian physics.  It is flat earth society material.

       As I said @8, "at base Koonan's claim is based on a simple misunderstanding that shows he completely misunderstands the nature of the greenhouse effect, or that he is completely dishonest, or that he is simply parroting memes provided by others without understanding what the mean and what they are related to. The science really is settled on this one, so there is no fourth option."

       2)  Although Koonin mentions the solar radiation, he appears to be caclulating his percentage from the 390 W/m^2 of thermal radiation (back radiation).  If he wanted to calculate the actual difference in backradiation, however, he ought to include the increase from feedbacks (WV and clouds) as well.  The total effect is an increase of approximately 20 W/m^2 (at equilibrium), or approximately 5% of the total back radiation at the surface.

       3)  Koonin does not even calculate the direct effect of the increase in CO2 accurately.  He appears to add the difference in radiative forcing for the change in CO2 (approx from the current 400 to the future 550 ppmv) to the current total anthropogenic forcing.  By excluding any changes in anthropogenic forcing other than that from CO2 he understates the change in anthropogenic forcing by mid century.  However, he does not state that he is discussing the change in anthropogenic forcing, but in the contribution of CO2 to the greenhouse effect, which makes it peculiar that he should us total anthropogenic up to 2011.  This does not, however, make any difference to his 1-2% value.

       Further, Keenan uses the TOA radiative forcing, not the change in CO2 contribution to the back radiation.  The two are distinct values both because of the higher temperatures and because overlaps with H2O are more significant for back radiation.  Again, this may not make a difference to the 1-2% estimate (due to the overlaps) - but Koonan does not know that.  The values he uses are not relevant to the percentage he estimates (which is  in turn irrelevant to the strength of the greenhouse effect).

33799. Russ R. at 06:21 AM on 27 September 2014
       Your questions on climate sensitivity answered
       

       There are a couple of points I'd make about Lewis & Curry's 1.64 degree C estimate of ECS (and by extension, all estimates derived from recent temperature observations, which are consistently lower than those derived from paleo proxy data or computer models).

       First, and most importantly, climate sensitivity is not really "a thing", in that it's not some fundamental, unchanging constant of the planet (like g= 9.8m/s²). Climate sensitivity is the sum total of a whole array of forcing and feedback mechanisms, which are themselves not constants. So, ECS isn't always going to equal 3.0, or 1.64 or some other fixed value. It can (and very likely will) vary under differing climactic conditions as those underlying forcing and feedback mechanisms vary. Treating ECS like a constant is a useful shorthand for back-of-the-envelope estimates, but it's nowhere close to a law of physics.

       As a simple example, consider Ice Albedo feedback. It only applies at the transition zone of polar ice extent (it has no effect in places that are permanetly frozen nor permanently ice-free), and as that ice extent retreats to higher latitudes with less surface area and insolation, the magnitude of IA feedback weakens, ultimately to zero. So, all else equal, you'd expect net feedback (and ultimately ECS) to be higher at the peak of an ice age vs. during an interglacial period. But all else won't be equal... other feedback mechanisms will each have their own dynamics, the sum total of which is unlikely to remain a constant. As such, different methods of estimation (paleo proxy measures vs current observations) might yield markedly different findings, and both can be entirely correct about the conditions that they measured. So evidence that ECS was 4 degrees Celsius in the distant geological past does not contradict evidence that ECS was 1.6 degrees Celsius in the very recent past. Furthermore, if ECS is not a linear constant, then extrapolations about the future become increasingly uncertain the further out you project.

       Second, models all very sensibly assume ice albedo feedback is positive (i.e. warming causes polar ice to retreat, which causes more sunlight to be absorbed, which causes more warming.) To just about everyone's surprise, for the last couple of decades, the southern hemisphere has experienced the exact oppposite... ice extent has increased in the face of warming, acting as a damper rather than amplifier (i.e. a source of negative feedback rather than positive) which would lower . Nobody can say for certain why this has occurred (there are several good theories), or for how much longer it will continue to happen, but in the long term, the anomaly should reverse and warming should lead to less ice and positive feedback. Looking at the recent temperature record, this anomaly will "contaminate" observations, and likely lead to discrepancies between observation based estimates of ECS and model based estimates. So evidence that ECS was 1.64 degrees C in the recent past does not contradict models that estimate ECS at 3.0 degrees C for the near future.

       Moderator Response:

       [Rob P] - There are no 'recent observations' for ocean heat content back in the 19th century. All these energy budget approaches have to use modelled estimates for that time period. 

        

33800. KR at 03:45 AM on 27 September 2014
       The Wall Street Journal downplays global warming risks once again
       

       JoeT - Thank you, that explains much about Koonin's statements. 

       Koonin expressing anthropogenic forcings as "1 to 2%" of insolation is akin to graphing the 0.9C warming over the last 150-200 years as Kelvin degrees with a baseline of oK - which has been done by denialists multiple times, appallingly enough. See Denial Depot for a rather amusing explanation of how this is done. He might as well have characterized the height difference between basketball player Yao Ming and a lawn gnome using a percentage of the height of the Empire State building. 

       In doing so Koomin is rather deceptively minimizing the extent of the changes, which at this time have increased temperatures to or beyond the peak value at any time in the Holocene, at any time during human civilization (Marcott et al 2013) - with more unrealized warming to come. That's a more realistic scale, one that more clearly describes how these changes will affect us. 

Prev  668  669  670  671  672  673  674  675  676  677  678  679  680  681  682  683  Next