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Comments 23951 to 24000:

23951. Tom Curtis at 23:33 PM on 20 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       pjcarson2015 @9:

       1)

       "Aren’t Valerie Taylor’s observations large-scale? They were 50 years ago and bleaching was as extensive as today’s."

       That is not what Valerie Taylor said.  She said that "In 1965 we went from one end of the reef to the other, over six months, and we found bleaching then."  The phrase "we went from one end of the reef to the other" refers to the extent of the travel.  It does not indicate the extent of the bleaching, which from what Valerie Taylor said, may only have been at a few locations on the reef.

       More importantly, the 1965 bleaching virtually escapes comment either in scientific publications, or on the web (not to mention from Valerie Taylor's films).  While the 2016 event was comparable to that of 1998 and 2002, 1965 certainly was not.

       2)  In the 1998 and 2002 events, 50% of effected reefs were bleeched, and there was lasting damage to 5% of reefs.  In other words, reefs can, but do not always recover from bleeching events, and the more intense the event the less likely is recovery.

       3)  First, bleaching events are not sporadic.  They were virtually unheard of prior to the 1980s, when they became common.  Undersea volcanic activity did not spike at that time, but sea temperatures did, and high sea temperatures are highly correlated with bleaching events.

23952. pjcarson2015 at 15:19 PM on 20 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       1. Rob P’s quote “We cannot yet be certain, but it is unlikely that mass coral bleaching has, until very recently, occurred for thousands of years.”

       Aren’t Valerie Taylor’s observations large-scale? They were 50 years ago and bleaching was as extensive as today’s.

       2. The corals also self-repaired later - despite CO2 levels being higher. If bleaching is caused by warming due to high CO2 levels, how is it that repair occurred at higher levels than the damage? In spite of this you conclude

       “Of course this doesn't have to be, but humans, collectively, have shown no intention of curbing industrial carbon emissions and so the demise of coral reefs seems inevitable.

       3. [You know where to find more on this topic.] As bleaching/repair occurs sporadically, one would suspect the cause to also be sporadic. Undersea volcanism fits the bill, both in location and in its irregularity, and it produces localised toxicity and heating; witness the Qld, etc floods in 2011 (when bleaching followed) and 2016 which match the preceding large Mag seismicity around Vanuatu. Expect more bleaching soon.

       4. The Eemian was about 2C higher than now (Vostok data). As you note, such temperatures may well recur.

       5. I’m still puzzled by the this article’s title when the Taylors - and you - note that bleaching has preceded the “warnings” by decades.

       Moderator Response:

       [Rob P] - "Aren’t Valerie Taylor’s observations large-scale?"
       
       And yet no film footage. Curious considering the amount of underwater filming that they have captured over the decades.  

23953. Glenn Tamblyn at 14:47 PM on 20 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Michael Sweet
       
       Two points. Your first one about heat transfer from cold to hot is referring to the 2nd Law of Thermodynamics. And this can be a bit confusing. Firstly, the 2nd Law refers to Net heat flow, based on all the energy flows between a hot and cold point. More importantly, the 2nd Law applies to a closed system. It does not apply to an open system. So if we think of the system and ask what the boundaries are, they need to preclude flows from outside the boundary. The atmosphere isn't that, there are flows from the surface, flows in from the Sun, flows out to deep space, and even miniscule flows in from other stars and deep space.
       
       Next, there are huge differences between the ocean and the atmosphere. Firstly, water is essentially imcompressible. So although pressure can increase hugely at depth very little actual compression occurs. So the density of parcels of water in the ocean doesn't vary by much; so much so that even changes in the salinity of sea water is a significant contributor to relativedensity change. And it is density differences that drives vertical convective movement.

       The atmosphere on the other hand has huge density changes with altitude, with pressure. As a consequence, vertical movement is much easier, and any tendency to stratification is easily disrupted. Also the impact of coriolis forces is more profound. Since air velocities are much higher than ocean current velocities, change in location happens much faster, both horizontally and vertically. So more Coriolis force generated turbulence and vorticity effects. Next with its much lower density air is more easily able to move vertically since it takes much less energy to move a parcel of air vertically than the same size parcel of water. Horizontal air movements can more easily trigger vertical air movements , not just horizontal movements that infill the volume previously occupied. So turbulence and mixing can happen more easily.
       
       So vertical movement is much easier. In the case of bottom heating which is how most heat flows into the Earths atmosphere, convection due to heating is easy to understand. However, even with top heating, which is more like what happens on Venus, mixing can still generate vertical movement. And some of the light from the Sun does penetrate to reasonable depth in Venus, enough to create some bottom driven convection.

       Also, wind speeds on Venus are higher than on Earth, up to 700 km/hr in the mid levels. More speed, more turbulence.
       
       So as long as there is anything that can generate reasonable vertical movements, in an optically thick, adiabatic situation, the Lapse Rate engine keeps running.

23954. Bob Loblaw at 11:28 AM on 20 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       One last comment for now. Mike Hillis has stated:

       "Only the sun can change the total heat content of the atmosphere."

       The is simply not true if you are talking direct heating, and you do not include oceans or land as part of the atmosphere. Most of the heating of the atmosphere comes from the surface, where most of the solar radiation is absorbed.

       This post by Keven Trenberth provides details and graphics, such as this image:

       

       The temperature structure of the stratosphere is driven by absorption of solar radiation (mainly UV), but the troposphere is dominated by energy gains from the surface in three forms:

       1. thermal energy gains from the surface
       2. latent heat contained in water vapour (changed from liquid to vapour at the surface - i.e. evaporation - and changed from vapour to liquid in the atmsphere - i.e., cloud formation).
       3. infrared radiation emitted from the surface and absorbed in the atmosphere.

       You can argue that all that energy ultimately came from the sun, but it reaches the atmosphere indirectly. Ignoring that indirect path is not a particularly good idea, especially in a discussion of lapse rates, adiabatic processes, and the greenhouse effect.

       Moderator Response:

       [RH] Resized image.

23955. Bob Loblaw at 11:15 AM on 20 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Since I've jumped in, I'll mention that wikipedia has an article on lapse rates.

       There are three important lapse rates in earth meteorology:

       • The dry adiabatic lapse rate applies when vertical movement of air occurs ("parcels") without any phase change of water (condensation, evapoartion, or sublimation). It is the direct result of the vertical pressure gradient.
       • The wet adiabatic lapse rate is like the dry - but water is changing phase so energy is being released to thermal energy in proportion to the latent heat of vaporization (or sublimation). It is most commonly seen in rising air with condensation (cloud formation), and results in a much smaller decrease in temperature with increasing height. Just how much less depends on temperature, through the saturation humidity vs. temperature realtionship.
       • The environmental lapse rate is simply the current observed relationship between temperature and height. There is a global average, but the local value varies widely depending on meteorological and climatological factors. It will only equal the dry or wet adiabatic lapse rates by pure conincidence. It is a blend of the adiabatic processes plus every other factor that affects vertical temperature and energy transfer.
23956. Bob Loblaw at 11:05 AM on 20 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Michael Sweet:

       Read Glenn's following text, and then let me try to explain it:

       Vertical movement of air downwards transfers heat, energy, downwards since the energy content of the moving parcel of air moves down with it. And a parcel of air moving upwards transfers heat, energy upwards.

       Glenn's statement applies to instantaneous transfer, not time-averaged. Energy content is a property of mass. If you move that mass in any direction, the energy it contains is moved with it. Upward movement of air is always moving energy upward; downward movement of air is always moving energy downwards. The exact vertical thermal energy flux is (heat content)*(vertical velocity). It does not matter - instantaneously - how the temperature of that air relates to air above it, below it, or around it. The simple movement of air moves energy.

       Averaged over time, net mass transfer is zero (otherwise you'd create a vaccuum somewhere and an excess of air somewhere else), but net energy transfer is not. Net energy transfer depends on whether the upward moving air is - on average - warmer or colder than downward moving air.

       This principle is actually used to measure the rate of sensible heat (thermal energy) transfer in the atmosphere, using a method called eddy covariance. The exact same method can be used to measure water vapour flux or CO2 flux (or any other measurable property), by using the commbination of humidity or CO2 concentration and vertical velocity. Water vapour flux is often used to determine surface evaporation, and vertical CO2 flux tells you about surface respiration/phiotosynthesis rates.

       Although you must use very-fast-response instruments, so you can catch every puff, the necessary instrumentation is available off-the-shelf.

23957. michael sweet at 09:27 AM on 20 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Glenn,

       I do not understand how energy can be transferred from a colder upper layer in the atmosphere to a warmer lower atmosphere.  It seems to me a contradiction of the second law of thermodynamics.

       The ocean forms a thermocline where circulation is restricted because the energy enters primarily from the top.  I htought that the energy to circulate the atmosphere (even on Venus) comes from the sunlight absorbed by the surface and then transferred upward.

       I have never an taken atmospheric science class so it may be some basic understanding that I lack.  Can you provide a link that explains better how the lapse rate is maintained?  I read the Wikipedia lapse rate article but I only understood what the lapse rate is and not how it is maintained in the atmosphere.  I did not find much helpful on Google, but I do not know what to look for.

23958. Tom Curtis at 09:15 AM on 20 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Mike Hillis @158:

       "The big question not answered here is Jupiter. How can there be a greenhouse effect on Jupiter when its atmosphere is made of H2? Answer, there isn't."

       Ignoring for a moment the high cloud in the Jupiter atmosphere (which also generates a greenhouse effect), Jupiter's atmosphere contains 3000 ppmv of methane, 260 ppmv of ammonia, 6 ppmv of ethane, and 4 ppmv of water, all of which are greenhouse gases.  The later two may be ignored, but the 3000 ppmv of methane and 260 ppmv of ammonia mean Jupiter's atmosphere is optically thicker for infra red radiation than is the Earth's.  Specifically, at 1 bar atmospheric pressure, the infrared optical depth of the Earth's atmosphere is 1.9, while on Jupiter it is 6.3 (τ₀ on Table 1 here).  That in turn means the effective altitude of radiation to space for Jupiter (ie, the altitude where the optical depth equals 1) is closer to the tropopause for Jupiter (optical depth = 0.064) than it is for Earth (optical depth = 0.050).

23959. Glenn Tamblyn at 08:33 AM on 20 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Mike
       
       You might find this article interesting, discussing the structure of planetary atmospheres and the GH effect. Notice how Jupiter (and Saturn, Uranus & Neptune) all have lapse rates in their tropospheres.
       
       Note also the discussion of likely gases in their atmospheres, including Ammonia and Hydrogen Sulphide, both GH gases.
       
       And consider something else. A GH Effect doen't have to just depend on incoming sunlight. Any heat source that can add significant amounts of energy into an atmosphere which is optically thick in the infra-red and thus capable of being roughly adiabatic will produce a GH effect.
       
       So in the case of the gas giants, they do have an internal GH effect because of clouds and GH gases, changing their inner tempeature due to the fact that they produce large amounts of heat internally. Whereas for the inner planets, internal heat is minimal but solar is significant - the heat source doesn't matter. So of all the planets, Mars has the least GH effect because:

       • Internal heat is insignificant
       • Solar is relatively weak
       • Its atmosphere isn't very optically thick
       • Convection is weak.
23960. Glenn Tamblyn at 07:56 AM on 20 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Mike Hillis
       
       "Put very simply, any vertical movement of air in any atmosphere either takes heat from a higher altitude or adds it to a lower one."

       This statement is untrue Mike. Vertical movement of air downwards transfers heat, energy, downwards since the energy content of the moving parcel of air moves down with it. And a parcel of air moving upwards transfers heat, energy upwards.
       
       So any vertical movement does move heat, but not all in the same direction. So any net movement of heat depends on the difference between thee two flows. And if the net of the two flows is zero, there is no effective flow.

       What determines whether the net heat flow is up or down? Whether the vertical temperature profile matches the Lapse Rate. If the upper air is too warm, net flow of heat is downward, cooling the upper level and warming the lower. If the lower air is too warm it is a net upward heat flow, cooling the lower level and warming the upper level.
       
       In near adiabatic conditions vertical air movement always generates a lapse rate.

       Think about the logic of your idea that movement in either direction produces downward heat flow. If that we true, then heat would just continually build up and up in the lower level. Without radiation to provide an alternative means of loosing heat, the lower level would become impossibly hot, not merely 500 C or so.

       As to your digression to Jupiter, vertical movement again explains the profile. If the depths of Jupiters atmosphere are optically thick, or on the case of Jupiter there are large quantities of clouds, then the adiabatic condition is met and a Lapse Rate can be created. There is no disparity.
       
       And with clouds present, Jupiter will have a greenhouse effect to some extent. On the graph you linked to, note the clouds of different materials in the lower atmosphere, all contributing to a GH effect. Note also that some of the clouds are water, so there will also be water as vapour present - more GH effect.
       
       Additionally, with some nitrogen present, there may be some GH type absorption and emission produced. This is due to what is known as 'collisionally induced absorption'. Molecules that aren't normally absorbers of IR radiation such as Nitrogen (N2) and Hydrogen (H2) can become transient absorbers and emitters during the finite time when they are colliding. This needs high densities and or low temperatures to make this possible, maximising the number and duration of collisions. So collisions between Nitrogen molecules on Titan for example allow N2 to create a GH Effect. And it has been theorised that collisions between N2 and H2 in the early atmosphere of the Earth may have contributed to the GH Effect then.

23961. HK at 04:15 AM on 20 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Mike Hillis @147:
       "Yup. Only the sun can change the total heat content of the atmosphere."

       OK, let’s try to figure out the expected consequences of that:
       As you know, Venus is closer to the sun than the Earth is (108.2 vs. 149.6 million km), but also has a much higher albedo (77% vs. 30.6% according to NASA’s fact sheet). When combining these two facts we find that each m² of Venus (mostly its cloud tops) absorbs less than 2/3 as much solar energy as the Earth does.
       So, if the total heat content in an atmosphere with a certain mass and composition is determined only by the amount of absorbed sunlight, we should expect the average temperature of Venus’ atmosphere as a whole – top to bottom – to be lower than the Earth’s, right?

       Well, I tried to calculate a "mass-weighted" average temperature for both atmospheres based on the temperature and pressure at different altitudes.
       The result for Earth was -22^oC and for Venus.....+354^oC !

       Any adiabatic process can obviously be ruled out as an explanation for this, as the very cold but very thin upper layers of Venus’ atmosphere have way too little heat capacity to "compensate" for the heat in the much hotter and denser lower layers. Actually, when I in my calculation lowered the temperature to absolute zero above 30 km, it only reduced the average for the entire atmosphere to +309^oC !

       And again: The spectrum of outgoing IR measured by the Venera probe reveals very clearly that the high temperature isn’t caused by any kind of internal heat source, but the simple fact that almost all the heat from the surface and lower atmosphere is prevented from escaping directly to space.

23962. RedBaron at 02:57 AM on 20 June 2016
       Timeline: How BECCS became climate change’s ‘saviour’ technology
       

       Sir Charles,

        It is my understanding that the Models used in the above don't specifically represent any single technology of drawdown. As far as technologies not existing, with respect to agricultural technologies (carbon farming) they certainly unequivocally do exist, so your youtube vid is unequivocally wrong on this point. Not only do they exist, there are many different ways to do it. Most of them are well vetted and have been for 20, 30 even 50 years or more. They were developed to improve soil fertility, not climate mitigation, but ultimately both are the same thing. There is more carbon missing from our soils than extra in the atmosphere. So if technologies designed to improve soil health, commonly refered to as "organic", were applied to carbon farm, there are many sources of information in how to do it. Technology is not the problem. Changing the infrastructure that supports agriculture is the only obstical left IMHO.

23963. SirCharles at 22:53 PM on 19 June 2016
       Timeline: How BECCS became climate change’s ‘saviour’ technology
       

       It's a shame that scientists include in their models technologies which don't exist yet.

       
       => Survivable IPCC projections are based on science fiction - the reality is much worse

23964. Glenn Tamblyn at 21:51 PM on 19 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       MA Rodger
       
       The Ideal Gas Law doesn't describe a process. It is a state law, so it describes a fixed state. Other things need to be considered to determine how and why the state changes. But the Ideal Gas Law will then describe the new state after a change.
       
       So better to say that nRT is a constant if mass doesn't change and internal energy doesn't change. T isn't a measure of the total internal energy of a collection of molecules. It is a measure of the translational kinetic energy of those molecules. 

       They also have energy in rotational motion, internal vibrations, and potentially electron energy levels. Also variations in potential energy of the molecules as they move closer or farther apart. Gravity is one source of potential energy change as objects move apart or together.  Electro-magnetic forcs produce similar. So too inter-molecular forces such as Van Der Waals forces. Then Quantum Mechanics also impacts this hugely, constraining possibilities.

       So Specific Heat Capacity, measured at constant Pressure, or constant Volume, is essentially posing/answering the question 'how much added energy manifests as increases in molecular translational kinetic energy - temperature - as opposed to increases in other modes of energy storage."
       
       Read this article at Wiki, looking at Degrees of Freedom etc.

       So what is the basis for your statement that includes Cp/Cv. "As a result an adiabatic process changing p and V does involve a change in temperature."?

       How are you determining that the total change in all internal energy forms - translational, rotational, vibrational, electron energy level, etc.  - will result in a matching changes in only the translational component of energy - temperature.

23965. Mike Hillis at 21:37 PM on 19 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Put very simply, any vertical movement of air in any atmosphere either takes heat from a higher altitude or adds it to a lower one. Is there vertical movement in an atmosphere? Of course. Must work be done to move the air up or down? Oh course, but that doesn't matter. All that matters is there is vertical movement. The fact that there is vertical movement proves that heat is being pumped downward. Even brownian motion does it.

       The big question not answered here is Jupiter. How can there be a greenhouse effect on Jupiter when its atmosphere is made of H2? Answer, there isn't. The same thing happens on Jupiter as happens on Venus.

       Venus' atmosphere is 93 bars. If you descend into Jupiter's atmosphere to a level where the density is 93 bars, the temperature is around 450 K according to

       LINK

       On that diagram, keep in mind there are 100,000 Pa to a bar so 93 bar is 9,300,000 Pa

       Moderator Response:

       [RH] Shortened link that was breaking page format.

23966. MA Rodger at 20:38 PM on 19 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Glenn Tamblyn @153,

       The gas equasion pV=nRT when stated as pV=constant does not define an adiabatic process. Ignoring any gravitational field, the equation is pV^γ=constant  where γ=Cp/Cv which for air =7/5. The reason for this is because the specific heat capacity at constant pressure (Cp) is not equal to the specific heat capacity at constant volume (Cv). As a result an adiabatic process changing p and V does involve a change in temperature.

       Mind, I don't believe this is, as Mike Hillis @146 asserts, something a high school chemistry teacher would be immediately familiar with. And it is certainly far less worthy of criticism than the assertion Mike Hillis continues with @146:-

       "pV = nRT says if you increase PV, the T goes up even though you have not added heat. The work done to change the parcel's elevation and raise or lower the PV is uneven solar heating of the atmosphere."

       Firstly, pV=nRT says nothing about added heat or not adding heat. Secondly, applying work to a parcel of air says there is added heat, so such a process cannot be adiabatic. (While the potential energy change could be construed conceptually as outside the boundary of the system under consideration, raising or lowering p or V cannot.)

       What is so odd about the position presented by Mike Hillis is that he is proposing what he describes as a Katabatic process which is a phenomenon born of the convection process and cooling at altitude. Yet Mike Hillis uses it to explain warming at altitude, the exact opposite to the convection process. Even the mash-up account he appears to be basing his nonsense on (Nikolov and Zeller's 2011 conference poster linked @122 above) and which overplays its use of the convection process still uses it in its usual direction. So I struggle to see where Mike Hillis is coming from.

23967. pjcarson2015 at 18:03 PM on 19 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       To Rob P.

       Thank you.

23968. RedBaron at 17:39 PM on 19 June 2016
       Timeline: How BECCS became climate change’s ‘saviour’ technology
       

       Trevor,

        Based on what? If I understand it correctly Kevin Anderson based his rebuttal mostly on using BECCS as a replacement for energy. Clearly not up to the task. Nor as I pointed out above, can true BECCS that is sequestering CO2 into geological formations work. But the quantity of carbon that can be sequestered by current agricultural soils is more than adequate in scale simply by changing the agricultural production models.  All you need is roughly 8Gt CO2e/ha/yr +/- to offset all AGW emissions worldwide. That's trivially easy from a technical POV. Getting the world to change agriculture and do what we know how to do a bit harder. So waste materials could be converted to biochar, but it wouldn't even come close to our energy needs. However, changing the production models can actually increase total food for humans on the same acreage. So that is no limitation. 

23969. Reason_4 at 17:31 PM on 19 June 2016
       Timeline: How BECCS became climate change’s ‘saviour’ technology
       

       Strikes me that while these high tech solutions are worth pursuing, the lowest, easiest, cheapest is being overlooked.

       In my experiments making biochar the easiest and best bang for buck is the pit method that anyone, anywhere can do with the highest tech required being a shovel and some means of putting out the fire - water if you have lots of it or some old roofing iron to smother the flames.

       https://www.youtube.com/watch?v=I1jAo7qd_Q8

       A 3rd world farmer could easily do this on site (no transport emissions) by coppicing fast growing (hopefully nitrogen fixing) trees - and either sell the biochar or enrich his/her own soil.

       Millions doing small things, year in year out could have an ongoing significant impact

       Great school project too. 

23970. Glenn Tamblyn at 16:44 PM on 19 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       So to a basic point, and the link you gave to the hockeyschtick site is an example of this.
       
       There are a number of climate denier sites that make this sort of argument, with dubious thermodynamics, that the existence of the Lapse Rate in some way invalidates the Greenhouse Effect. The 'Venus isn't hot because of the GH Effect, it is hot because of the Lapse Rate' type arguments. What they all uniformly don't get is something simple.
       
       The Lapse Rate is a part of the Greenhouse Effect!
       
       There are 3 processes that work together to create the GH Effect.

       1.  Radiative Balance. The Earth has to radiate enough energy to space to balance the energy arriving from the Sun. If it doesn't radiate enough, heat builds up and everything fries, radiate too much and everything freezes. So 'the Earth' needs to be warm enough to generate the right amount of radiation to space. Too little and it warms until its right. Too much and it cools until it is right. Radiative Balance is always adjusting the temperature of 'the Earth' to keep it where it needs to be to match the flows.

       Notice I have said 'the Earth'. Because actually it isn't the Earth, it is that part of the Earth where the radiation to space originates from. Radiation doesn't originate from 1000 meters down in the ocean for example. So Radiation originates from 'somewhere'. And Radiative Balance acts to manage the temperature of the 'somewhere'. Balance defines what that emission temperature is, but not where it comes from.

       2.   The presence or absence of GH gases in the atmosphere determines what altitude radiation to space originates from. More GH gases means it originates from hgher in the atmosphere. And if there were no GH gases present, then it would originate from the surface. GH Gases determine where the emission temperature is set by Radiative Balance.
       
       For the Earth that is around 5 km up and the temperature is around -18 C. For Venus that is over 50 km up and -80 - -90 C. And if the amount of GH gases is changed, then the altitude changes. So if we added enough GH gases to raise the average emission altitude for the Earth from 5 km to 6 km, then the 6km level would then be driven to an average of -18 C by Radiative Balance.

       3.   Then the presence of the Lapse Rate pump re-balances the vertical temperature profile around the temperature at the average emission level. Because importantly, the Lapse Rate defines relative temperatures vs altitude, not absolute temperatures. It is Radiative Balance that sets that and the GH gases determine where. The Lapse Rate then drives the average temperature of the rest of the atmosphere column to fall into line with that.

       
       So in my example, if GH gases increased the emissions altitude by 1 km, then that level would warm to an average of -18 C, and the Lapse Rate pump would then drive matching temperature changes through the rest of the air column. Including the surface. If the actual value of the Lapse Rate remained constant* (at -6.5 C/km), then adding enough GH gases to raise the emission altitude by 1 km would result in all parts of the air column warming by 6.5 C right up to the limits where the Lapse Rate pump works.

       So the surface gets warmed because the upper atmosphere has to warm and atmospheric mixing propagates that up and down.

       The Lapse Rate doesn't disprove the GH Effect. It is a part of it.

       Sites like hockeyschtick, with their dodgy understanding, don't get this and end up spreading mis-information.
       
       * Actually the Lapse Rate will change. In a warmer would there will be more evaporation and condensation. So the contribution from evaporation and condensation in determining the actual value of the Lapse Rate will be more important and the Lapse Rate will fall a little. This is called the Lapse Rate Feedback, it is a negative feedback, and offsets a little of the warming from more GH gases.

23971. Glenn Tamblyn at 16:12 PM on 19 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Next Mike, your comment to me and this comment &147.
       
       "Yup. Only the sun can change the total heat content of the atmosphere.".
       
       Of course thats true, but it isn't what we are discussing, or the point of my previous comment. We are discussing what can change the heat content of individual parcels of air, not the entire atmosphere. It isn't what changes the total heat content of the atmoisphere thar is at issue, it is the heat content at a smaller scale.
       
       And at that scale there are processes that can change heat content of air parcels, I have described them in my previous comments.
       
       There is a vertical movement of energy whan air rises and falls. Because the energy in an air parcel gets carried with it. So rising air carries haet to a higher altitude. Descending air carries heat to a lower altitude. Then pressure equalisation brings about a redistribution of that heat between the vertically moving air parcel and its surrpindings. And as a concequence, a vertical temperature distribution is created. This article about the Lapse Rate is worth reading. That is what it is all about.
       
       So there is an engine that transports heat up and down until an equilibrium is established where the atmosphere has a vertical temperature profile based on the Lapse Rate for that planet and atmosphere. And if the atmosphere weren't in equalibrium, with one layer too warm or cold compared to other layers, this active pumping engine works to re-establish the profile.
       
       So in the case of Venus, with most incoming solar energy being absorbed in the upper atmosphere, atmospheric mixing generates a substantial vertical temperature difference. And in the case of the Earth, where more incoming solar energy is absorbed at the surface, the same mixing generates a vertical difference as well.
       
       Importantly, this only works when there is enough vertical movement and when the process is adiabatic. On Earth, this applies in the Troposphere but as we get up to the Stratosphere, these conditions breakdown. As the air thins, convection driving vertical movment drops right off, and as the atmosphere thins, radiation to space becomes a powerful factor, so things are no longer adiabatic. With substantial radiation loss to space, this trumps the weak Lapse Rate driver of circulation. So the temperature profile of the Troposphere is dominated by the Lapse Rate, but the temperature profile of the Stratosphere is dominated by radiative effects.
       
       So in summary. You are right about there being a strong vertical heat pumping system but you are incorrect about the mechanism that drives it. Importantly, this mechanism is a heat distribution system. It is always working to balance amounts of energy at different altitudes to maintain a vertical temperature profile. So if energy is being added to the system at different altitudes from the Sun or tiny amounts from geotherml heat (or on Earth human energy usage) and at the same time being lost to space at other altitudes as infrared radiation, the Lapse Rate pump is continually moving this incoming heat around, trying to establish the temperature profile. And the net effect, after lots of moving around, is that the incoming energy is transported to the location that it needs to be at to get out to space. But the temperature profile of the entire optically thick, convective region of the atmosphere will be maintained by the pump, not just some parts of it.
       
       So for Venus, where absorption and emission of radiation both largely happen at higher altitude, none the less the Lapse Rate pump will still ensure that lower levels in the atmosphere are hot enough to maintain the temperature profile.
       
       

23972. Glenn Tamblyn at 15:40 PM on 19 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Mike

       Lets consider a piston and cylinder with some air inside it. The air and the piston/cylinder are at a constant temperature.

       Now I push the piston in, reducing the volume to half. If I do it quickly enough so there is no time for heat transfer between the air and the cylinder/piston then the process is essentially adiabatic.

       So what should happen. No heat transfer, no mass transfer, so nRT is constant. So V is halved and P is doubled, and T doen't change surely.

       But that isn't what happens. The work needed to compress the piston has to be added in. So the total internal energy of the air increases, T increases so nRT goes up. V is halved, and P increases by more than double! And we now notice that T has increased.

       This often confuses people. They see the temperature increase and assume that the act of being more compressed is why T is higher.

       It isn't.

       T goes up because energy has been added due to the work needed to compress the piston.

       There is a reverse case. If we allow the volume to double, P would be cut in half. Now if this expansion had to do work, then internal energy would be expended to do it, P would drop by more than half, and temperature would fall.

       However, it is possible to contrive a situation where we can achieve this volume increase essentially without any work being done.

       The setup looks like this.
       
       A chamber is divided in two by a sliding door. On one side there is air at pressure P and temperature T. On the other side there is a vacuum. Everything is in thermal equilibrium, air and chambers.

       Then we very rapidly slide the door away and allow the air to expand into the other chamber. No work needed to be done on the air to allow it to expand.

       What happens?

       Volume doubles, n is unchanged, P is cut in half, and T remains unchanged!

       This is called Joule Expansion and was first demonstrated by James Prescott Joule in 1845 although others had known about it before hand.

       There is actually a cooling of the gas that occurs but this is due to a secondary process, not related to the simple picture of PV = nRT we are discussing here. This secondary process is discussed at the end of the Joule Expansion article and also a related one on the Joule-Thompson Effect which is essentially about throttling processes.

       Again the cooling seen in a real gas due to the JT Effect isn't intuitive so people can be misled and think that the act of being less compressed is the cause of the cooling. It isn't.

23973. Glenn Tamblyn at 15:35 PM on 19 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Mike Hillis
       
       "Heat stays the same but T goes up".
       
       This statement is a nonsense. If heat in the gas (actually it is more accurate to talk about the 'internal energy' of the gas) doesn't change, temperature cannot change. Because temperature is the direct measurement of some of that internal energy.

       The following article on Wiki has a good discussion of the Thermodynamic (or Kinetic) definition of Temperature.
       
       The eqution relating the internal energy of a gas, actually the kinetic energy of translation of the molecules in the gas, is as follows:

       E = 3/2 k_BT_k

       where:

       E is the mean kinetic energy of a molecule in the gas, in Joules

       k_B = 1.3806504(24)×10−23 J/K is the Boltzmann constant

       T_k is the kinetic temperature in kelvins (K)

       Temperature is directly proportional to the internal energy of the molecules.
       
       Temperature is the measurement of their internal energy.
       
       So saying heat doesn't change but temperature does is nonsensical. Temperature is the measurement of 'heat'.
       
       So if the amount of heat doesn't change, temperature cannot change, by definition.
       If the amount of heat does change, temperature must change, by definition.

       Next, this comment.
       
       "The equation states that product of pressure and volume is a constant for a given mass of confined gas as long as the temperature is constant.

       So, as long as T is constant and the gas is confined (V is constant), then, yeah.

       For the rest of us, PV = nRT"
       
       Mike if the temperature is constant (T is unchanged), then the internal energy hasn't changed. If the mass is constant (n is unchanged) then nRT is constant. So PV is constant, whether confined or not.
       
       What can happen when gas parcels are unconfined is that internal energy might change - T changes. Or mass might change - n changes. Without one of those changes PV is still constant.
       
       But when we are talking about bulk parcels of air in the atmosphere, there is very little mixing and it occurs relatively slowly. So any change in n is minimal. And similarly, without mixing into a parcel, convection cannot transfer much heat quickly into a parcel. Coinduction is a very very weak heat transfer mechanism in gases. And in the Troposphere where the air is 'optically thick', radiation is a poor energy transferer. So the assumption of Adiabatic processes is actually quite good. Heat transfer into a parcel is minimal.
       
       So vertically moving parcels of air essentially can't change n, essentially can't change internal energy through heat transfer since things are adiabatic. So nRT is constant so PV is constant.

       However, as they move to different altitudes they need to equalise pressure with the surrounding air. And this happens fairly quickly.
       
       So P must change to equilibrate with the surroundings. OK, thats fine, V changes to match so that PV remains constant. But there is a problem. And your first item in your list highlights this:
       
       "1. Parcel moves down and compresses".
       
       The parcel can't compress itself! It has to be compressed by something outside it.

       And that something is the surrounding air. Pressure equalisation means that the surrounding air compresses the parcel. PV would remain constant because everything is Adiabatic (see here for a definition of an Adiabatic Process) except that it is not an Isenthalpic Process.
       
       There is energy transfer into the parcel!
       
       This is not as a Heat Transfer - that satisfies the Adiabatic condition - but is an energy transfer into the parcel as work done on it. (See the definition of Work here)

       The surrounding air has to perform mechanical work on the parcel to compress it. And this adds energy to the parcel. This then means the internal energy of the parcel has increased. T has increased! So PV can increase.
       
       This is why descending air masses warm up. They are compressed by the surrounding air and this adds energy to them, increasing their temperature.
       
       And the reverse applies to ascending air masses. Pressure equalisation means they have to do work on the surrounding air to expand and match pressures. Sp energy needs to be expended by the parcel to do that work. Since the process is Adiabatic, the only energy source available to supply the energy for this work is the parcels internal energy. So the parcels internal energy drops - it cools.

23974. pjcarson2015 at 15:24 PM on 19 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       [Firstly to John Abraham; I should have said this earlier - I wish you well with your adoption.]

       To Moderator Rob P.

       The title of this article is “Climate scientists have warned us of coral bleaching for years. It’s here”

       My #4, to which you seem to object, simply states

       1. That it has been observed since at least 1965. (By Ron & Valerie Taylor of whom you should be well aware as you say you scuba.

       2. I observe where such previous and current coral bleaching has occurred.

       In other words, you don’t seem to notice I agree with you that bleaching occurs. I also agree that it will happen in future – but that it has also been observed to occur further back in time than suggested by the article.

       Is it necessary for “dude” “spam” and “cockamanie”?

       Moderator Response:

       [Rob P] - Heat-related coral bleaching on the GBR, IIRC, goes back at least as far as the 1920's (anecdotally at least). But those were small localized events, and nothing like the large-scale bleaching events occurring today which can be many thousands of square kilometers in extent.

       We cannot yet be certain, but it is unlikely that mass coral bleaching has, until very recently, occurred for thousands of years. The last major event believed to about 4000 years ago in the eastern Pacific due to, the authors claim, a more extreme ENSO cycle - see Toth et al (2012). And the last Interglacial, the Eemian, saw a global retreat of coral reefs away from the equator too (Kiessling et al [2012]).

       So past and present 'observations' in the peer-reviewed scientific literature paint a consistent picture: when summer sea surface temperatures become too hot, coral bleach and often die. With a warming ocean we expect the frequency and intensity of bleaching to increase - as we are witnessing. In the not-too-distant future the tropical oceans will become too warm and coral reefs will be destroyed - as has happened in the past many times when things got too hot for them.

       Of course this doesn't have to be, but humans, collectively, have shown no intention of curbing industrial carbon emissions and so the demise of coral reefs seems inevitable.

23975. Trevor_S at 14:25 PM on 19 June 2016
       Timeline: How BECCS became climate change’s ‘saviour’ technology
       

       I think it was either Kevin Anderson or Jason Box who pointed out we'd need arabale land one to two times the size of India to make this work.  Not sure where we will find that, then clear it all... Seems like it's nothing more than justification to put off until tomorrow (making the problem worse by chewing into the ever decreasing emisisons budget) what we need to do today.  Lower emissions... significantly.

23976. Mike Hillis at 13:05 PM on 19 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       @149

       PV = nRT is given here:

       https://en.wikipedia.org/wiki/Ideal_gas_law

23977. Mike Hillis at 12:48 PM on 19 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       @ 149

       From your link to Wikipedia:

       "P V = k where P is the pressure of the gas, V is the volume of the gas, and k is a constant.

       The equation states that product of pressure and volume is a constant for a given mass of confined gas as long as the temperature is constant."

       So, as long as T is constant and the gas is confined (V is constant), then, yeah.

       For the rest of us, PV = nRT

       Moderator Response:

       [RH] Edited out post @150 rather than delete (per request) in order to preserve the numbered comment reference used in this thread.

23978. Mike Hillis at 12:45 PM on 19 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       @ 149

       From your link to Wikipedia:

       
       "P V = k where P is the pressure of the gas, V is the volume of the gas, and k is a constant.

       The equation states that product of pressure and volume is a constant for a given mass of confined gas as long as the temperature is constant.

       So, as long as T is constant and the gas is confined (V is constant), then, yeah.

       
       For the rest of us, PV = nRT

        

       Moderator Response:

       [RH] Corrected comment @151.

23979. pjcarson2015 at 11:18 AM on 19 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       To repeat,

       You replied as Moderator. Which facts and observations in my post are an issue?

       Moderator Response:

       [Rob P] This blog is based upon the findings of the peer-reviewed scientific literature and data gathered by reputable scientific organizations. Whilst it provides rebuttals to many of the common climate myths, we don't debunk every single myth some dude on the internet just came up with. If you don't accept the findings of decades of scientifc research, that's up to you, however it's not encumbent on SkS to debunk every cockamamie idea that comes along. Nor do we provide a service for spam to sites to promote the absurd. So no more links unless they are to legitimate sources (see the Comments Policy).
       
       Casual readers, however, might be interested to see the anomalous sea surface temperatures on the Northern GBR in 2016 that caused so much coral mortality. Note the extraordinary anomalous bleaching stress (thick black line) in the bottom left-hand side of the image, as compared to the three previous (non-bleaching) years.

23980. michael sweet at 09:57 AM on 19 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Mike Hills,

       Any  chemistry text will say that Boyles law is PV=Constant (Wikipedia) or page 297 Corwin Introductory Chemistry (textbook for the local Community College). Your claim that PV can somehow increase on their own without the addition of energy from an outside source is simply false. You must provide a scientific reference (blog science is not good enough) to support your absurd claim that PV can increase on their own.  Since PV = constant, the only way to change the temperature is to add energy.  Read Glen's comment for the correct explaination of how the work done by the atmosphere changes the heat content of the parcel.  (Heat and work are both forms of energy so work done = heat increase).

       The thread at WUWT where Goddard claimed that CO2 would fall as snow at the south pole was deleted after even Watts realized that it made him look stupid to have such junk on his site.  Goddard was then banned from WUWT for being so unscientific.  (Imagine what it takes to get banned from WUWT for being unscientific!!)

       It is clear that this thread is a waste of time and others have been doing a good job countering your blog "science".  I will no longer comment.

23981. Digby Scorgie at 09:56 AM on 19 June 2016
       Timeline: How BECCS became climate change’s ‘saviour’ technology
       

       Chriskoz @2

       Andy Skuce concludes as follows:

       "At best, CCS and BECCS would be able to provide a stopgap to a more sustainable future."

23982. Mike Hillis at 09:21 AM on 19 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Michael sweet @144

       Keep in mind that Steve Goddard thinks CO2 can fall as snow at the south pole and be sequestered there forever.

       That is an error. This is what Steve Goddard actually says:

       https://stevengoddard.wordpress.com/2012/06/12/antarctic-temperature-drops-below-the-freezing-point-of-co2/#comments

23983. Mike Hillis at 09:01 AM on 19 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       @ 145

       Are you saying that adiabatic processes can’t change the total heat content in the atmosphere of Venus (or any other planet) and that the high temperature near the surface is only caused by a redistribution of heat?

       Yup. Only the sun can change the total heat content of the atmosphere.

23984. Mike Hillis at 08:51 AM on 19 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       @144

       Heat and temperature are directly proportional in a given parcel of air.

       Yes, as long as you don't change the pressure or volume, which can change the T without changing heat content. High school chemistry teachers should know this.

       pV = nRT says if you increase PV, the T goes up even though you have not added heat. The work done to change the parcel's elevation and raise or lower the PV is uneven solar heating of the atmosphere.

       I will not state my argument again because repeating oneself is against comments policy.

23985. RedBaron at 08:33 AM on 19 June 2016
       Human CO2 is a tiny % of CO2 emissions
       

       William, 

        Most likely the soil causing it. That's good news and bad news. The good news is that it is reversable. The bad news is that we are fairly unlikely to do so. As although it really is easily reversable, there is a huge institutional resistance to even trying, and actually the trends are to accelorate it rather than mitigate it.

23986. RedBaron at 08:17 AM on 19 June 2016
       Timeline: How BECCS became climate change’s ‘saviour’ technology
       

       Getting closer, not quite there yet. Next step is forget putting CO2 in geological formations. The carbon needs to be in the soils. But it is doable.

       Technical Brief: The Liquid Carbon Pathway

        

       Now the Liquid pathway alone gets you between 5-20 Gt CO2/ha/year. (the 32 Gt CO2 mentioned in the source is a bit of an outlier. Yes people are getting those results and even better in some cases, but 5-20 is more common) That alone if used on enough agricultural land would sequester long term in the soil between 62% to 250% world wide yearly fossil fuel emissions. But since biochar is carbon too, and in a stable form, there is even more. Since making biochar can produce energy too...... This would be the next step...if things like solar and nuclear couldn't keep up.

23987. HK at 08:07 AM on 19 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Mike Hillis @143:
       "Adiabatic changes in temperature don't add or lose total heat...."

       Are you saying that adiabatic processes can’t change the total heat content in the atmosphere of Venus (or any other planet) and that the high temperature near the surface is only caused by a redistribution of heat?

       (A short yes or no is sufficient)

23988. michael sweet at 07:31 AM on 19 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Mike Hills,

       Your arguments started out interesting but have gone way down.  I suggest you review basic chemistry and physics before you post again.  You need to stop reading from the blog source you are getting your information from.  Keep in mind that Steve Goddard thinks CO2 can fall as snow at the south pole and be sequestered there forever.  If you want to convince readers here you have to get the High School Chemistry (which I teach) correct.

       Heat and temperature are directly proportional in a given parcel of air.  If the temperature increases as the parcel as it sinks, the heat increases. The heat has to come from somewhere.  It cannot come from the parcel itself as that would violate the first law of thermodynamics.  Glenn's explaination that the energy comes from the work the surroundings does (or that a rising parcel does on the surroundings) is the correct one.    Read his post again if you are unclear about where the heat comes from.

       Venus is the classic example of a runaway greenhouse effect.  Arguing that Venus is not a greenhouse planet will not get you any converts at a scientific site.  

       Can you find a scientific reference (paper or textbook) that caims Venus is not a greenhouse (I note that you have not referred to any scientific papers in your arguments, only blog science)?  If you cannot perhaps you should consider that it is because Venus really is a greenhouse and your blog science is incorrect.

       Your claim that heat can be transferred from the cold upper atmosphere to the warmer lower atmosphere is also a violation of the laws of thermodynamics.

       I will try not to comment again since dogpiling is against the comments policy.

23989. Ger at 01:32 AM on 19 June 2016
       Timeline: How BECCS became climate change’s ‘saviour’ technology
       

       chriskoz @2: most CO2 plants do take in is from rotting materials in the ground/on the ground. Most agricultural residues represent for the larger part the fast amount needed: for England alone there is a 14 million tons a year, relative easy, to obtain mass representing a 140 million GJ in primairy energy. And most agricultural is still for food (arable lands for food are still available). 

       Hungry world is struggeling not that they don't have arable lands but that modern high productive crops do need far more water and fertilizers per ha for which the farmers lack investments. Furthermore they lack the means to create the risk mitigation measurements for a planet heating up, especially in regions where it is already hot and with less water. 

       Greenhouses in hot & dry areas near sea's can turn a dessert in a food production area. Any CO2 can be used to enhance growth of plants in hydrocultures. You don't need much more, except for a ship load of investments. 

23990. chriskoz at 00:45 AM on 19 June 2016
       Timeline: How BECCS became climate change’s ‘saviour’ technology
       

       Digby@1,

       We made a little bit of progress with our ideas about CO2 capture. I think CCS (old term) and BECCS are diferent concepts. CCS, also refered to as "clean coal", was an excuse by mining moguls to promote burming more FF, becaue we can, in theory, burn it "clean" i.e. do not emit CO2 into atmosphere. The idea is best debunked and ridiculed by aSkS post Sequestering carbon nature's way: in coal beds, esp. its graphic.

       Now, BECCS is something totally different: shows that it's possible to net remove CO2 from atmosphere - employing fast growing biomas - burn the biomass and store captured CO2. And the beauty of the concept is: you obtain energy from the process, unlike in "clean coal" where you assume to input energy into the process, presumably coming from the coal itself, reducing its thermal efficiency, so making it even more "dirty" than it was in the first place. However, I'm still skeptical how realistic is the deployment of  BECCS on the scale needed. The amount of biomass cycling must be enormous, because the its energy density is smaller than that of quality coal (we sgopped burning wood to charcoal in favour of mining coal in 19th century precisely for that reason), and if there is enough land to grow said biomass, then an efficient way to gather it and bring to BECCS facilities and enough power is left to compress and store CO2 underground. That requires big infrastructure. Just raising such infrastructure requires lots of money and energy. How many years does it need to operate to break even on CO2 emissions?

       The existing PV technology, although it's not negative emmsions, offsets its production emissions after ca. 1 year of its life. I'm not so sure about BECCS. In practice, BECCS may turn out to be utopia, because simply there is no enough land to start with B, while hungry world is struggling to turn every arable land for food production. Needless to say cobtinue with ECCS...

23991. Mike Hillis at 23:49 PM on 18 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Adiabatic changes in temperature don't add or lose total heat, because when the volume goes down the T goes up so total heat in parcel remains the same. Just the temperature changes. The amount of heat in the parcel of air remains the same, all that changes in the temperature and volume according to

       PV = nRT

       So if PV goes up, T goes up, but when the temperature goes up the total heat contained stays the same because the volume goes down. That's how it works. Heat stays the same and volume goes down, the temperature goes up. Follow with me closely:

       1. Parcel moves down and compresses

       2. Heat stays the same but T goes up

       3. Parcel equilibiates T with lower elevation surrounding air by adding heat to it

       4. Parcel moves up and expands

       5. Heat in parcel stays the same but T goes down

       6. Surrounding air adds heat to parcel to equilibriate T

       All heat added to parcel from surrounding air is at higher elevation, all heat lost from parcel is at lower, so heat is moved from high elevation towards low until it reaches the surface.

       This is for ALL vertical motion of air, whether is be large air masses, small parcels, or brownian motion, and at any and all elevations.

       And since horizontal motion of air is many times faster than vertical, the air parcels are quickly moving around the planet, which is why the poles on Venus are the same temperature as the equator, and the night side is at warm as the daylit side.

       Glenn @ 142 says

       this energy has to come from somewhere. And the only energy source available is the internal energy of the rising air parcel

       No, the source of energy is the Sun

       Moderator Response:

       [RH] Please avoid using all caps, per comments policy. 

23992. Glenn Tamblyn at 18:05 PM on 18 June 2016
       Human CO2 is a tiny % of CO2 emissions
       

       william
       
       I would think its most likely an effect of El Nino. Even if carbon sinks start to shut down, they wont be that precipitous.

23993. Tom Curtis at 17:15 PM on 18 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       pjcarson2015 @4:

       "Incidentally, in my previous post I referred to chapters in my site, “Planet Earth Climate Topics” at ..."

       Yes.  As always you spammed an add for your site which contains, as usual, a great paucity of facts, a significant number of inventions, and a curious refusal to correct errors.  On this topic it contains no information in addition to the text of your post @3 and therefore is not an independent source of evidence, or indeed a source of evidence at all.

       As to your post @3, yes coral recovers from bleaching.  Recovery, however, takes time.  If there are repeated impacts during that time, recovery will be slow, or not occur at all.  As can be seen below, events causing damage to reefs have accellerated in recent times, and for the Great Barrier Reef, that has lead to a long term decline in coral cover (second figure):

       

       (Source)

       

       (Source)

       As you can see, that decline has been precipitous for the southern most (and most disturbed) portion of the reef.

       What is worse, as can be seen from calcification studies, that decline comes at the tail of a reversal of a century long increase in reef health in the mid 20th century (figure d):

       

       Granted that bleaching events currently account for only 10% of reef damage.  However, the GMST during the last bleaching event was less than the 2 C limitation on global warming aimed at by international agreements.  If global warming is restricted that limit (currently very unlikely on present policies), that means we will be getting multiple equivalent bleaching events every decade within fifty years.  That is far to rapid a pace to recover from, so that bleaching events alone would be sufficient to destroy most of the Great Barrier Reef.

23994. Digby Scorgie at 15:14 PM on 18 June 2016
       Timeline: How BECCS became climate change’s ‘saviour’ technology
       

       Professor Kevin Anderson has some scathing things to say about BECCS.  I'm also reminded of the article by Andy Skuce on 13 January 2016: "The quest for CCS".  At best it is just a stopgap measure.

23995. Glenn Tamblyn at 12:52 PM on 18 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Mike Hillis at @135

       "as I already said, as the air moves down it adds heat to the air it decends to. As it ascends, it takes heat from the air it ascends to. In BOTH directions, it transfers heat from higher to lower"
       
       Actually Mike, you have this back-to-front. As air moves down heat is added to it from the surrouning air. And as air rises heat is removed from it by the surrounding air. You are leaving important aspects of the problem out - potential energy changes and work.
       
       A parcel of air that is rising in the atmosphere is being lifted by some force, air pressure, buoyancy, whatever. So work is being done on it. However, because it is rising, the air parcel is also gaining potential energy. When we work out the math, the work done on the parcel exactly matchs the potential energy gain. So conservation of energy says no net change in the energy of the parcel. At the scale of air movements in the atmosphere there is little mixing between parcels, so no scope for significant heat transfer between them And in a dense atmosphere radiative transfer is very poor. So the movement of the air parcel is essentially adiabatic - no net heat flow in or out.
       
       So the parcel would rise to a higher altitude essentially unchanged same volume, same pressure, same temperature. However, pressure can't stay the same. At higher altitude air pressure is lower, and air pressure must equalise. So the parcel has to expand to equalise pressure with the surrounding air. But in order to expand the parcel has to push the other parcels around it aside to make room for its expansion. It has to do work on them. So there is an energy transfer from the rising parcel to the surrounding air as work. But conservation of energy says this energy has to come from somewhere. And the only energy source available is the internal energy of the rising air parcel. In order to supply the energy needed to push other air parcels aside, the rising parcel loses internal energy. Its temperature drops as it transfers energy to its surroundings.
       
       For descending air parcel it is the reverse. as it descends, pressure equalisation means that the surrounding air compresses the parcel, doing work on it, adding to its total energy which since the situation is adiabatic can only manifest as an increase in the temperature of the parcel.
       
       Rising air heats its surroundings and is thus cooled by them, falling air is heated by its surroundings and cools them.

23996. pjcarson2015 at 11:14 AM on 18 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       You replied as Moderator. Which facts and observations in my post are an issue?

       [Incidentally, in my previous post I referred to chapters in my site, “Planet Earth Climate Topics” at pjcarson2015.wordpress.com]

23997. HK at 08:13 AM on 18 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Mike Hillis @136:
       My point is that Venera’s measurements clearly show that the IR radiation escaping from Venus can’t come from near its surface, but from much colder and therefore much less radiating layers in its upper atmosphere.
       If the high temperature was caused by any physical process that adds heat rather than slows down the heat loss to space (as the GHE does), the spectrum of the outgoing IR from Venus would look completely different. Using the wavenumber scale (as done in the graph), the peak radiation would be more than 20 times higher (thus the need to enlarge the y-axis!), and shifted to about 1440 cm^-1.

       BTW, the 15 µm band (667 cm^-1) is important for the Venusian greenhouse effect exactly because almost all the heat loss to space happens from the very cold, upper layers of the atmosphere and not from near the surface.

23998. william5331 at 07:40 AM on 18 June 2016
       Development banks threaten to unleash an infrastructure tsunami on the environment
       

       To understand what is happening you can read the updated version of Confessions of An Economic Hit Man by John Perkins and The creature from Jekyll Island by Edward Griffin.  The Secret History of the United States by Stone is also very revealing.  In a sentence, The world Bank has little to do with the world except  that it is a mechanism for America to exploit the world and increase its hegemony over it.  Huge loans are made to countries that can't possibly repay them and when they default, America gets her pound (more like a ton) of flesh.  Countries are forced to privatize their services which American corporations snap up.  Favorable votes in the UN are also sometimes the currency of repayment.  Right at the base of it is that banks hate when countries, businesses and individuals finance their advancement from their own profits.  They want to give loans because that is how they make their money.  They will put pressure on wherever they can to achieve this aim.  Griffins book, in a very readable and clear fashion, shows what a scam the Federal Reserve (and other reserve banks) are.

23999. scaddenp at 07:39 AM on 18 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Mike Hillis, just to be clear here - do you believe that if you put venus atmosphere into an ordinary GCM using only known physics, then the temperature and isothermal structure of surface is not reproduced?

       ie it is "unexplained" by known physics?

24000. Tom Curtis at 07:29 AM on 18 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Mike Hillis @135, you also said:

       "Tidal forces and the friction it gererates will eventually stop the rotation of Venus, but until then, the motion, all motion, within its atmosphere, will continue to generate heat katabatically."

       What you should have said is that, "until then, the motion, all motion, within its atmosphere, will continue to generate and remove heat in equal proportions katabatically" unless you take the delussory view that all atmospheric motion on Venus is downward.

       What this mechanism does, and the only thing it does, is to generate the lapse rate in the troposphere.  That is, it establishes a linear relationship between the temperature difference and distance along the vertical axis within the troposphere.  It cannot, by itself, determine the exact value of the temperature at any point in the troposphere.

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