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Comments 23701 to 23750:

23701. Mike Hillis at 21:26 PM on 23 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       I prefer a graph which shows actual flux, not log of intensity, to get a more accurate visual image of what's going on, and one which covers Earth's entire upwelling IR spectrum of 7 microns to 100, not one artificially cut off at 10 and 25 microns. In this case we see a CO2 band of IR emitting at 220 K but that the majority of Earth's IR radiates from near the 300 K Planck curve, which means it's not being absorbed by any greenhouse gases. Yes I do know about the 9.6 micron O3 band which also radiates from higher elevations and lower temperatures.

       graph

       Earth's greenhouse atmosphere is like an actual greenhouse, with one section of glass representing CO2, another section for H2O vaor, and most of the roof wide open.

23702. Tom Curtis at 21:25 PM on 23 June 2016
       Climate's changed before
       

       Glenn Tamblyn @527, here is the relevant paper showing low CO2 levels at the start of the Ordovician glaciation.  It is discussed in passing by Richard Alley in his famous lecture.

23703. Glenn Tamblyn at 20:37 PM on 23 June 2016
       Climate's changed before
       

       Doodad - nice tag by the way :-)
       
       Is this a drive-by or do you have specific points to make.
       
       And by the way, current CO2 is more like 400, not 350 ppm.
       
       Yes there are mechanisms that draw down CO2, just as there are mechanisms that can raise it. The key question is over what timescales. Come back in a million years and our disruption of the carbon cycle will have disappeared from the climate system. However its signature will be visible for 10's to 100's of millions of years in the geology.
       
       How could an Ice Age have happened when CO2 was 5000 ppm (very approximately)? Perhaps if they dropped!
       
       Your figures of 4% lower solar and 5000 ppm suggest you are referring to the End Ordovician Ice Age (and Mass Extinction Event). You might help discussion if you clarify that.
       
       So using the standard definition of the impact of changing CO2 levels - similar impacts for each doubling, 350 ppm (your number) to 5000 ppm, is under 4 doublings - 700, 1400, 2800, 5600. So somewhat under the impact of one doubling. One doubling changes radiative balance by 3.7 w/m^2 so around 14.8 w/m^2 in total. Actually when we look over larger ranges of CO2 concentrations this change is lower, so less than 14.8.
       
       Then solar was 1310.8 rather than 1365.4 watts per square meter today - your figures. The current estimates are more like 1361, the 1365 figure was likely a small calibration error from an earlier satellite. Small detail.

       So on your figures, a difference of -54.6 w/m^2. But we need to divide by the ratio of the Earths frontal area to its total area, so divide by 4. -13.65 w/m^2.
       
       Hmmm... Not much difference. So if CO2 dropped back then, an ice age is entirely plausible. A drop from 280 to 180 ppm today is associated with a swing into an ice age. That is the equivalent of a swing from 5000 to 3200 ppm back then. What might trigger that? The evolution of vascular plants drawing down CO2? Major volcanic events sequestering CO2 due to weathering?
       
       We don't know everything about the past but it sure fits with CO2 being a significant factor.

23704. Glenn Tamblyn at 19:40 PM on 23 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Mike, actually not off-topic, just a more detailed exploration of the topic. You might find this interesting
       
       
       
       This is the data from the HiTran spectroscopic database for the Spectral Intensity of CO2 vs wavelength.
       
       This is the starting point for evaluating absorption/emission strength. As you can see the vertical scale is logarithmic. The roughly triangular shape of the graph either side of 15 on a logarithmic scale is the primary basis of the logarithmic nature of CO2 forcing.
       
       So peaks either side of 10 are also visible, and a peak near 5. However they are 4 orders of magnitude weaker than 15.
       
       However this is only part of the picture. There is also a process called Line Broadening which, particularly in the lower atmosphere, smears out each line substantially. Extend this to Venus or Jupiter like atmospheres and individual lines can actually be smeared across much of this graph. There is more on this here.
       
       As a result the actual spectrum observed by satellites is a product of some complex stuff.
       
       Here is one such satellite measurement, from 1969.
       
       
       That spike at 15 micron, at the centre of the CO2 'notch', doesn't just come from the top of the troposphere. It actually comes from the upper stratosphere where temperatures are actually higher.
       
       So yes, there is lots of wavelength specific detail. Most of the radiation from 9 to 11 is from the surface except near the centre of that where Ozone plays a role - that is just visible on the above graph as a dip starting at the right extreme.
       
       However, at a broader level, dealing with averages across wavelengths, the broad picture I have painted is still valid.

23705. Tom Curtis at 18:28 PM on 23 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       pjcarson2015 @26, a person who assumes scientists are uninformed buffoons as you do deserves no respect.  Especially when you do so on the basis of such transparently inadequate arguments.

23706. Tom Curtis at 18:24 PM on 23 June 2016
       Climate's changed before
       

       Doodad @522, the primary effect of warmer weather on cold blooded creatures is that they become faster in their actions.  There is a limit on this, primarilly based on the fact that they must use different enzymes in different temperature ranges, and above 60 C they do not have appropriate enzymes.  But you are correct, for lizards, and cockroaches, and flies and mosquitoes, and other cold blooded creatures, warm conditions are good conditions.

       Likewise, warm conditions tend to be good conditions for small warm blooded creatures.  This is because they have a higher skin area to volume ratio, allowing more efficient cooling; and because they have higher basal temperatures so that wet bulb temperatures need to be more elevated to cause heat protration and death than they do for large warm blooded creatures (such as humans, and human livestock).  So, within limits, warmer climates are good for rats and other rodents.

       In general, warm weather is good for all of hour pests and parasites.

       I'm not sure why you think that is a good thing.

       In contrast, for humans in the tropics, summer temperatures already reach or exceed the range that allows efficient cooling on a regular basis.  This can be ameliorated by drinking large quantities of water, finding shade, and resting - the combined effect of which is to significantly lower work efficiency.  So, already in the tropics warmer climates will have a negative effect on the economy just from the direct effect of heat on humans.  However, with a sufficient warming, the tropics will regularly reach wet bulb temperatures leading to death of humans and large livestock (anything larger than a chook).  Put simply, most of China, all of India and all of South East Asia, the north part of Australia, most of Africa, the mediterrainian and Middle East, Central America and the north part of South America including essentiall all of Brazil will become seasonally uninhabitable.

       This massive catastrophe is very unlikely if we take serious measures to limit climate change, but laregely unavoidable if we insist on burning our conventional fossil fuel reserves to exhaustion.  Currently we are doing something towards mitigating climate change, but branching out to burn unconventional fossil fuels as well.

23707. Tom Curtis at 18:09 PM on 23 June 2016
       Climate's changed before
       

       Doodad @524, using the standard formula, top of atmosphere insolation 400 million years ago was 96.6% of the current value of 1360 W/m².  However, that is the insolation per meter squared prior to the effect of albedo, and for an area perpendicular to the Sun's rays.  The Earth is effectively a sphere so that only a small part of it is perpendicular to the Sun's rays at any time, and half of it is in darkness at any time.  Averaged over the Earth's surface, that means the incoming sunlight is one fourth of the top of atmosphere insolation.  (The difference is just the ratio between the area of a circle perpendicular to the Sun's rays and just large enough to cast the Earth entirely in shadow, and the area of the Earth, ie, the ratio of πR² to 4πR², where R is the radius of the Earth.)  Further, the Earth's albedo of 0.3 means 30% of sunlight is reflected to space and does not contribute to warming the Earth.  Therefore the average sunlight that warms the surface amounts to (Top of atmosphere TSI * (1 - albedo))/4, or 238 W/m².

       Assuming the same albedo, that means the average sunlight warming the Earth's surface 400 million years ago amounted to 229.95 W/m².

       Four hundred million years ago, there was approximately 4000 ppmv of CO2 in the atmosphere:

       

       4000ppmv is 10 times 400 ppmv, or 3.32 doublings (2^3.32) of 400ppmv.  Each doubling of CO2 has a forcing of 3.7 W/m², so 4000 ppmv has a forcing of 12.84 W/m².  Adding the 229.95 insolation gives a warming effect of 242.23 W/m², or 4.23 W/m² relative to the current forcing.

       For whatever it is worth, the forcing difference between 400 ppmv and 5000 ppmv (3.64 doublings) is 13.48 W/m².

       I assume this relates to your claim that there have been ice ages with CO2 levels at 5000 ppmv.  That claim is false.  To understand why, it must be understood that the graph of CO2 concentration shown above has a resolution of 10 million years (top of fourth page).  If there is a five million year period with low CO2 immediately preceded by a period with high CO2, it will be shown as a period of average CO2 because the resolution of the graph is incapable of distinguishing the two periods.  A later publication by the lead author of the previously linked study had a look at CO2 levels during periods of glaciation with data from high resolution strata.  In almost every case, the ice ages came in periods of low CO2 (< 1000 ppmv) that were too short in duration to show up in the 10 million year resolution graph.  The few cases not covered by his paper have since also been shown to have low CO2 by the discovery of new high resolution strata.

       And just a point of vocabulary, geologists call any age with sea level, or near sea level glaciers an ice age.  The periods of massive glacier advance commonly called ice ages by non-scientists are, by geologists, called glacials; while the warm periods between glacials are called interglacials.  Thus, because of the sea level glaciers on Greenland and Antartica, we are currently in an ice age.  Even with projected melt of ice sheets from a 5 C warming, there will still be sea level glaciers in Antarctica, and we will still be in an ice age.  Absent more detailed information, the fact that there was an ice age in the past does not tell us whether it was equivalent to a glacial (as you are probably assuming) or an interglacial (as we are now).

       Note that a 5 C warming is approximately equivalent to the equilibrium effect of an increase of CO2 from 280 ppmv to 975 ppmv (ie, effectively the 1000 ppmv limit found in the paper from the second link above).   

23708. Doodad at 16:28 PM on 23 June 2016
       Climate's changed before
       

       Is a 4% less solar irradiance than the present enough to level out and invert the effects of a dozen times the amount of carbon dioxide than the present? Please affirm if these are true:

       the carbon ppm back then was over 5000

       the carbon ppm now is around 350

       the solar irradiation now is around 1365.4 watts per square meter, therefore back then it was 1310.8

        Under these conditions:

       over 5000 carbon ppm + 1310.8 w/m³= ice age temperatures 

       350 carbon ppm + 1365.4w/m³=16ish degrees

       Doesn't this reflect the insignificance of carbon levels?

       We can all easily see how much solar irradiance affects the earths temperature. Just compare the temperature at night with the temperature in the day. Thats how much sunlight can change temperatures. 

       According to your articles, if we increase CO2 levels in the air by 3 times now, a sudden 1% decrease in solar irradiance will plunge us into another ice age? That is to say, the temperature difference made by 300% increase of CO2 is dwarfed by the temperature difference made by a 1% increase in solar irradiation? 

23709. pjcarson2015 at 15:23 PM on 23 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       Tom Curtis. I haven’t bothered to answer your #25 #5, etc, because of your lack of respect. (It won’t help your comprehension but try using a spell-checker.)

23710. Doodad at 13:52 PM on 23 June 2016
       Climate's changed before
       

       CO2 levels long long ago have been over 5000 parts per million, while at the present they are a mere 300. And yet when the CO2 levels were 5000 ppm, the earth was in an ice age. Sure, CO2 isn't the only driver of climate change. But that just reflects what little change CO2 can make to temperatures. Can you tell me, why there was an ice age back then? Have you fully investigated the other driver of climate change? How do you know that other driver is not also playing a part in the current warming? Does that mean even if current CO2 levels were to rise to 5000 ppm, it wouldn't have a significant impact on our climate? When CO2 levels were high in the past(there were also plenty of small fluctuations), WHAT caused them to drop back down? Climate scientist have poured all of their research into what CO2 does to the climate, but what about the other driver? 

       Moderator Response:

       [PS] Please see the "CO2 was higher in the past" article and comment there if unclear. I have already pointed you to the article (on weathering) about what caused reduction in CO2 in past. The Search box on the top left or the Arguments, Taxonomy of the menu bar are a good way to find information about these common myths. And before you make assumptions about what climate scientists have and have not studied, I strongly suggest you look at the IPCC WG1 report.

23711. Doodad at 13:29 PM on 23 June 2016
       Climate's changed before
       

       Mammals have the ability to adjust to warmmer weather. We have built in systems to help us reduce body heat. Sweating. Reptiles also will not be harmed by warmer weather. Reptiles cannot adjust their body temperature, they can only use the environment. If it gets warmer, they can easily stay in the water, or under shade, which is what they have been known to do. Colder weather in contrast is the main reptillian killer. There is no simple way like going under a shade or jumping into the water to elevate their body heat. When it's cold, it's cold, and it's cold everywhere. 

       Moderator Response:

       [PS] This is extremely simplistic description but I am not sure what point you are trying to make? In what way is your comment relevant to this topic? Are you contesting the evidence in the fossil record that sudden increases in temperature also correspond with mass extinctions?

23712. Tom Curtis at 13:16 PM on 23 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       John Hartz @23, I was expecting a bullshit answer from pjcarson2015, and you got it.

       We can check his hypothesis independently, however.  Suppose a low level concern for reef health as a background.  Then prior to the massive increase in interest in global warming circa 1990, mentions of "Crown of Thorns Starfish", and "Coral bleaching" should follow similar patterns prior to 1990s, after which interest in coral bleaching should take of.  In contrast, if coral bleaching was virtually unknown before the 1980s, there should be little mention of coral bleaching prior to then, and then mentions should rise with the rise in coral bleaching events.  Looking at an n-gram search of the two terms, however, we find a rise in interest in COTS in the 1970s that was not matched by a similar rise interest in coral bleaching, as would have been the case had bleaching events been a regular occurence and the concern only be with reef health.  Following the global bleaching event in 1983, and especially that of 1998, there is a rapid rise in interest in coral bleaching, which fell significantly a few years after the 2003 bleaching event.

       That is, the documentary evidence strongly favours the rise in bleaching events resulting from a rise in SST as the cause of the interest in bleaching events.

       Of course, if that is not evidence enough, I also am old enough for my observations to be contemporaneous; and my observations are incompatible with pjcarson2015's thesis.  Of course, such anecdotal claims are irrelevant as evidence, in either direction - but Carson cannot count his observations as evidence while excluding mine with out transparent special pleading. 

23713. pjcarson2015 at 11:59 AM on 23 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       #23 John Hartz. “How do you know this to be true? “

       Because I’m old enough for my observations to be contemporaneous.

       Do you have evidence to the contrary?

23714. Digby Scorgie at 09:59 AM on 23 June 2016
       A brief history of fossil-fuelled climate denial
       

       amhartley @6

       You have a point.  My hypothesis until now has been that deniers can be divided into three groups, but perhaps I should make that four.  My three groups are as follows:

       Firstly, there are the psychopaths.  You'll find them in the fossil-fuel industry.  They know that climate change is a threat but would rather maintain their wealth and power in the short term in expectation that global warming will only become serious in the long term.  They are the people behind the climate-science disinformation campaign.

       Secondly, there are the suckers.  These are the ordinary people who have fallen victim of the disinformation campaign.  My assumption is that such people would accept the fact of climate change if they were exposed both to the evidence of climate change and the evidence of the fossil-fuel industry's deceit.

       Thirdly, there are the psychotics.  These are the flat-earthers whose irrational world-view has no place for the evidence of climate change.  Of course they "sincerely disbelieve a climate-change problem exists".

       However, I now see the possibility of a fourth group.  These are the fanatics who compare the evidence for climate change with the proposed solutions to the problem and conclude that the latter is worse for them than the former.  Or can this group be lumped in with the psychopaths?

23715. Doodad at 06:44 AM on 23 June 2016
       Climate's changed before
       

       If past global warmings have been caused mainly by CO2, and it has caused temperatures higher than the present, then how did temperatures come back down and even into an ice age later? There were no animals trying to reduce CO2 emissions back then? That means CO2 emission came back down for some natural caused reason. Does that mean CO2 would also come back down naturally after a period of time after the present warming?

       Moderator Response:

       [PS] Please read the intermediate version of this article. Climate has changed before for many reasons but in these changes,  GHGs operate as amplifiers. Over very long time periods earth has a crude "thermostat" in rock weathering (releasing Ca). See  here in particular for details and also here and in referenced papers for more. Also, see Mathews and Weaver for how fast temperatures could change under zero emissions etc.

23716. amhartley at 06:31 AM on 23 June 2016
       A brief history of fossil-fuelled climate denial
       

       John Cook, the claim that “People who fear the solutions to climate change, such as increased regulation of industry, are more likely to deny that there is a problem in the first place – what psychologists call “motivated disbelief” ” seems a little uncharitable, if not an invalid argument. Some, at least, of those people might actually sincerely disbelieve a climate change problem exists, leading them to assert that no ‘solutions to climate change’ are needed.

       As much as I disagree with Karl Popper on some things, I applaud him for giving others the benefit of the doubt, & trying to strengthen their arguments (before tearing them down, when needed). Would it be possible to adjust the claim about “motivated disbelief” to follow Popper’s example to us all?

23717. Mike Hillis at 04:11 AM on 23 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Glenn, this is slightly off-topic but when speaking of emission elevations and temperatures, and optical thickness, you must specify wavelength. On Earth, emission of 15 micron IR occurs at the top of the troposphere at cold temperatures, but 9, 10, or 11 micron IR for examples, are emitted to space from Earth's surface (if not blocked by cloud) at very warm temperatures.

23718. Glenn Tamblyn at 03:15 AM on 23 June 2016
       A brief history of fossil-fuelled climate denial
       

       I agree with Tom. In terms of the history of the science, this question was not understood till the 50's and the piece was reporting the scientific view of the time.
       
       However it is still an example of some PR from the petroleum industry. At that time perhaps not unreasonable, it is how an industry responds as the science develops that is the key issue.

23719. Tom Curtis at 03:02 AM on 23 June 2016
       A brief history of fossil-fuelled climate denial
       

       rocketeer @1, in 1937 scientists did not know the rate at which CO2 dissolved into the ocean, and more importantly, how rapidly it mixed with the deep ocean.  They did not know this until nuclear testing increased the production of C14, giving them a marker with which to trace this in the 1950s.  Nor did they know the rate at which CO2 was released by volcanoes (which I believe was not estimated until the 1990s) and hence did not know the rate of natural weathering.  Most importantly, they had no clear data showing an increase in the atmospheric CO2 levels (not obtained until Keeling set up the Mauna Loa observatory until the late 1950s).  In short, until the late 1950s, they did not have evidence that refuted that hypothesis.

        It follows that that is not an example of climate change denial, but only of a scientist being wrong in the absence of relevant data.  Scientists do that all the time.  It is what drives them to find the relevant data to test alternate theories.  Of course, presented today when we do have all that data, or indeed, anytime after the mid 1960s, that theory is denial because it flies in the face of some conclusive evidence.

23720. BBHY at 02:53 AM on 23 June 2016
       A brief history of fossil-fuelled climate denial
       

       Another factor is that climate denial has effectively been turned into a "shibboleth".

       People like belonging to a group, whether religous, political, idiological, or otherwise, and for many people people the group the feel affinity for is conservatism. A shiboleth something that people use to identify themselves as part of a particular group, and climate denial has been turned (intentionally, IMHO) into a way for people to identify themselves as a member of the conservative group.

       The big difficulty with this is that trying to argue with those folks by presenting evidence and facts about climate change simply reinforces to them that you are "not one of them", an outsider, and therefore possibly not to be trusted. Studies have shown this is often the case, presenting more evidence about climate change to people can actually make them even more certain that their original view is the valid one.

23721. Dcrickett at 01:18 AM on 23 June 2016
       A brief history of fossil-fuelled climate denial
       

       A few weeks ago I finished reading "This Changes Everything" by Naomi Klein. I have not been able to fault the book on accuracy; I do wish it were to show less political bias (altho Ms Klein tried valiantly to minimize this). Nonetheless, the book did make me think. Particularly about how and why intelligent, rational, well-meaning folks don't "get it" on the need for massive and immediate action (the less immediate the action, the more massive it must be).

            Political people tend to ignore the "hair-on-fire" urgency of climate action because (a) they can ignore it and get away with it; and (b) their action paradigm does not see the utter nonnegotiability of Nature. Negotiation and compromise are core to a proper political action paradigm, but are immiscible with the science paradigm.

            Unfortunately, this has consequences every bit as bad as the misunderstanding spawned by denialism.

23722. rocketeer at 00:06 AM on 23 June 2016
       A brief history of fossil-fuelled climate denial
       

       This is the earliest example of climate change denial I am aware of.  i suppose at this early date it could qualify as genuine skepticism rather than denial, but it does come from the petroleum industry so...  Also, the arguments may sound familiar as they are still in use 80 years later.  Enjoy.

       Science - Supplement July 30, 1937

       THE CARBON DIOXIDE CONTENT
       OF THE AIR
       Even though man has released into the atmosphere
       some 180,000,000,000 tons of carbon dioxide gas by the
       burning of mined fuel during the last half century, the
       plants of the world each year return this carbon dioxide
       a thousand fold through their decay or combustion.
       Dr. Robert E. Wilson, president of the Pan American
       Petroleum and Transport Company, who reports this result
       in Industrial and Engineering Chemistry, also notes
       that the fears of those people who shudder at the
       " greatly " increased carbon dioxide content of the air
       which is produced by modern industrial activity, are unfounded.
       If all the carbon dioxide dumped into the
       atmosphere in the last 50 years had not been removed by
       returning the elements involved to the earth in some form
       or other, the carbon dioxide content of the atmosphere
       would have increased only two-thousandths of one per
       cent. in that time; from 0.03 to 0.032 per cent.

       The controlling factor which determines how much carbon
       dioxide there is in the air is the water of the earth 's
       oceans. Available data indicate there is some 30 to 40
       times as much carbon dioxide dissolved in the ocean as is
       present in the atmosphere. The average partial vapor
       pressure of this carbon dioxide is probably largely what
       determines the average carbon dioxide content of the air,
       so that well over 90 per cent. of any excess carbon dioxide
       introduced into the atmosphere eventually finds its way
       into the ocean, leaving the composition of the former
       virtually unaffected.
       The combined result of all our mining and chemical
       activity to date has made but an infinitesimal alteration
       in the composition of the earth 's crust or sea water.
       And this, despite the fact that in the past half century
       some 50,000,000,000 tons of carbon have been obtained as
       either coal, lignite, crude petroleum or natural gas

23723. John Hartz at 23:49 PM on 22 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       pjcarson2015 @20:

       You assert:

       6. Until AGW raised its head ca 1985, not much concern was raised about bleaching, and was reflected in when or if it was reported.

       How do you know this to be true? 

23724. Tom Curtis at 21:55 PM on 22 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       scaddenp @20:

       "Was there a coral bleaching event in 1965? yes. Is it comparable to events today in severity and coverage?- you need the larger scale evidence. Valerie says no but you appear to not to like that statement, but project heaps from the other one. Drawing a long bow from one observation instead of decades of study is highly unconvincing to me."

       As previously noted, Valerie Taylor only state the extent of her, and her husbands travels in 1965, not the extent of the bleaching.  However, she does not state that the bleaching was limited.  From the information she gives alone, it could have been one or two small patches of bleaching, or a bleaching event comparable to that in 1998 and 2016.  Of course, we know on other grounds that the later is not the case.  Further, she does not even state when the bleaching occurred, or its cause.  The bleached areas they saw could have been remnants of a bleaching event in the previous two years.  The bleaching could also have been caused by large inflows of fresh water (as happens on inshore reefs during floods).  It may have even be a Crown of Thorns Starfish outbreak, whose initial impact of the reef is superficially similar.

       Not only is her account vague, but it is also that of a non-expert.  She is a very experienced diver, but so also is Ove Hoegh-Guldberg, who was collecting for an Oceanarium before he left high school, and has been diving for at least 39 years.  What Ove Hoegh-Guldberg adds to that is a lifetime of intensive research which makes him an expert, something pjcarson would immediately acknowledg, if only Ove Hoegh-Guldberg agreed with him.  Unfortunately he does not, so he has to talk up a non-expert who does not explicitly disagree rather than acknowledge genuine expertise.

23725. Tom Curtis at 21:24 PM on 22 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       scaddenp @20, I think you will find that Ove is Australian Research Concil Laureate Fellow, Professor Ove Hoegh-Guldberg.  His also John Cook's boss, and author of a very relevant series of posts on SkS (Part 1, Part 2, Part 3).  I am unsure on what basis PJ Carson claims to be on a first name basis with him (his only described interaction certainly does not cut it).

23726. scaddenp at 20:06 PM on 22 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       1/ it is your framing i am objecting to. Your inference doesnt go with the other quote does it? Tom here pointed out that you were inferring more from her statement than it allowed.

       2/ I have no idea who Ove is apart from fact that he is professional scientist studying coral. Comments about him or his age sound like rhetori to me.

       5/ Sorry, on one TV show you cannot show pictures that give any framework to how widespread an event is, nor its context in larger time frame. 

       Was there a coral bleaching event in 1965?  yes. Is it comparable to events today in severity and coverage?- you need the larger scale evidence. Valerie says no but you appear to not to like that statement, but project heaps from the other one. Drawing a long bow from one observation instead of decades of study is highly unconvincing to me. 

23727. Glenn Tamblyn at 19:58 PM on 22 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       Mike Hillis
       
       Here is whats on that page.
       
       

       • Vertical air movements produce a relative temperature gradient in an optically thick atmosphere with locally adiabatic conditions.
       • These movements move heat up and down to establish and maintain that gradient, even in the presence of heat additions into the atmosphere from incoming sunlight, internal heat emissions from the planet etc. at any altitude.
       • Since emissions to space are dependent on optical thickness, emission to space will originate from that altitude where the atmosphere, of whatever planet, is transitioning to being optically thin.
       • For reasons of radiative balance the temperature at that level will tend towards the emission temperature needed to maintain radiative balance.
       • Vertical air movements will balance atmospheric temperatures around that balance level, producing the GH effect.
       • This occurs on Venus, Earth, modestly on Mars, on Jupiter, Saturn, Uranus, Neptune, Titan as a starting list.
23728. Glenn Tamblyn at 19:36 PM on 22 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       pjcarson2015
       
       If it is H2S from volcanoes, presumably you can point to evidence along the current pathways from them to the GBR where we can see elemental Sulphur deposited on the sea floor as a result of H2S reacting with dissolved Oxygen and precipitating out. Whereas in contrast, when major H2S events have occurred in the geological record they come about at times of depleted oxygen in the oceans and large scale anaerobic bacteria population explosions

23729. pjcarson2015 at 16:59 PM on 22 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       #17 scaddenp.

       1. I quoted Valerie in #3. What have I misunderstood?

       2. Ove was about 7 years old in 1965, and completed his PhD in 1982; how could he compare relative bleaching if he hadn’t seen past bleaching? (See 5 below).

       3. Wasn’t Ove the one appearing on Sir David Attenborough’s program “Death of the Oceans” the effects of higher CO2 levels on pH by blowing his own breath (ca 5% CO2) into seawater? A tad unrealistic - deceptive even?

       4. I actually had a “conversation” with Ove (after one of his radio presentation) via a Bulletin Board concerning reef problems – it was dial-up then! - about 20 years ago. I asked him if they tested for H2S. Nope. They’re unlikely to find something if they don’t test for it!

       5. One person’s observations are on TV for all to see. I’ve seen it.

       So, either Ove has seen it – proving Taylors’ vision exists/existed- or he hasn’t - and his statement is false.

       You choose which.

       6. Until AGW raised its head ca 1985, not much concern was raised about bleaching, and was reflected in when or if it was reported.

23730. scaddenp at 15:22 PM on 22 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       What is doubted, it not what Valerie said, but your understanding of what she observed. I havent found the data sources of her observations for evaluation but I did find this   from Ove Hoegh-Guldberg in which her observations are put in context:

       "Underwater film makers like Valerie Taylor (personal communication) who extensively filmed on the Great of Barrier Reef during the 1960s and 1970s never saw coral bleaching on the scale seen since 1979. "

       Comparisons with times of past high temperature have to be considered against the rate of warming which is far faster then any previous occurance except maybe PETM when nearly lost corals altogether.

       And frankly, I have far more faith in systematic surveys than in one persons observations.

23731. chriskoz at 13:55 PM on 22 June 2016
       2016 SkS Weekly Digest #25
       

       With 2016 being federal election year in both US (rather trivial entertainment) and AUS (serious head to head contention), election polls are on the menu. E.g. in AUS:
       Federal election 2016: Polls point to rising support for climate change action

       Most interesting fact is that climate mitigation action demand grew mostly among NLP (party denying AGW problem, similarly to GOP in US although not to a ridiculous extent) supporters. The AGW awareness in general electorate in OZ is now largest since 2006-2008, when Inconvenient Truth came out.

23732. denisaf at 11:24 AM on 22 June 2016
       Development banks threaten to unleash an infrastructure tsunami on the environment
       

       This discussion focusses on the flow of money in providing infrastructure to provide society with services at ecological costs. However, it does not take into account the fact that the proposed infrastructure construction irreversibly uses up many forms of irreplaceable natural resources. It is an unsustainable process that is bound to decline in the near future. Money flow will become impotent as nature bats last!

23733. pjcarson2015 at 11:13 AM on 22 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       oderator’s response to KR.

       “So we'd expect largescale coral bleaching in 2016 but not 1965. “

       Just as I wrote and explained for 2016 in #9 point 3.

       How do YOU explain the warm peaks in your presented graph?

       Are you still not accepting pre 1965 bleaching? (It was observed in 1965, therefore it happened pre-1965 – which matches your graph’s temperature peak.)

       Yet you do accept it in the 1920s!?

       [BTW. The Taylors were among the first “environmental warriors”, fighting to protect sharks, etc and the GBR. Yet you doubt her observations!]

       Moderator Response:

       [Rob P] - The March sea surface temperature (SST) anomaly on the GBR in 1965 was 0.61°C below the 1961-1990 mean, whereas the March 2016 SST anomaly was 1.33°C above the mean. March 1965 ranks as the 20th coolest year in the entire record. Coral would not have been bleaching in 1965 because SST's were too warm.

       And the large year-to-year fluctuations in sea surface temperature on the GBR, despite a long-term warming trend, are largely due to ENSO. In the 2nd year of an El Nino event, anomalously warm surface water entrained in the surface circulation is transported to the Coral Sea via the South Equatorial Current - the westward flowing current which is the northern arm of the anti-clockwise rotating South Pacific subtropical gyre. The anomalous warmth raises the summertime SST above normal - which is why the peaks in the graph tend to occur in El Nino years.     

23734. Tom Curtis at 08:01 AM on 22 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       It now turns out that pjcarson2015 @11 (third point) now wants us to believe that:

       i)  Undersea volcanoes change ocean chemistry in their region so little as to be undetectable except over the last ten odd years;

       ii)  But that they change the ocean chemistry so much thousands of miles downstream that they cause mass bleachings; and that

       iii) Undersea volcanoes have been undetectable except in the last ten years;

       iv) But that he has been able to establish a clear correlation between such eruptions and bleaching events going back over decades; 

       v)  And the established connection between bleaching events and high SST going back over four five decades swhould be ignored based on his evidence, which by his own claim cannot cover more than a decade or so.

       He also wants us to believe that mass coral mortalities have been detectable going back to the 1870s (see graph @5 reproduced below), and major Crown of Thorns Starfish (Acanthaster) outbreaks have been detectable since the 1900s, while mass coral bleachings cannot possibly have been detected prior to the 1960s.  Indeed, given the rapid ramp up of mass coral bleachings in the 1980s, he really requires us to believe they were not significantly detectable until the 1980s, for if he does not he must accept that they have recently become more frequent with the rise in SST.

       

       In my opinion, he has already qualified to dine at Milliways, and should give it a rest.

23735. william5331 at 07:01 AM on 22 June 2016
       New methods are improving ocean and climate measurements
       

       That was a great article on how one goes about comparing older with newer technologies but at the end of the article, I was expecting a comment on what difference this correction in fall rate of the XBT has made in our understanding of how much the ocean has warmed since measurements began.  Does it increase or decrease the actual amount of heat we think the ocean has stored.

23736. Mike Hillis at 23:07 PM on 21 June 2016
       Venus doesn't have a runaway greenhouse effect
       

       @ 168 Glenn Tamblyn

       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.

       Thanks Glenn, looks like we're on the same page now.

23737. pjcarson2015 at 16:02 PM on 21 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       KR #12: Comprehensive numbers and trends for pre and post 1960s, please show them!

       Do you also doubt Taylors' observations? Eyesight and film is better than model numbers.

       Do you have ANY data to show that current changes are different? Absence of data arising because no-one was looking does not count.

       #13: How does examining AIRborne CO2 give you evidence of UNDERsea volcanoes!! They don’t produce airborne CO2 – unless from shallow seeps, they are generally kms below surface and CO2 dissolves. I mentioned an example in #3 and #9, and the large storms on the eastern coast over the past weeks are further examples. (Large Mag around Vanuatu again.)

23738. KR at 12:41 PM on 21 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       Incidentally, although difficult to localize, undersea volcanoes are well accounted for in total volume, by examining airborne CO2 isotopic fractions. Your imagined volcanic influences simply don't exist, not in any proportion or time sequence that would support your arguments.

23739. KR at 12:28 PM on 21 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       pjcarson2015 - It's all about numbers and trends, and singleton videos are in effect only anecdotal evidence without the numbers. The comprehensive numbers and trends from both periods indicate that current changes are, indeed, unlike those of the 1960's.

       Moderator Response:

       [Rob P] - Indeed. In March 2016, sea surface temperatures on the Great Barrier Reef were much warmer than March 1965. So we'd expect largescale coral bleaching in 2016, but not 1965. 

       

23740. ghagilaris at 12:15 PM on 21 June 2016
       There is no consensus
       

       A point about messaging to the public. In the "Consensus of Scientists" video, John Cook makes the well-reasoned point about relying on expertise. But I think the general public could reasonably still be confused by the fact that non-expert scientists aren't showing nearly as strong of a consensus based on the current surveys. Is this because the wrong question is being asked of them, at least in terms of the type of question that is relevant to the public? Should there be a different survey that asks whether they trust the findings of the climate scientists in regard to climate change? In other words, should the quesiton be posed so that non-experts are not being asked about their personal confidence based on their expertise but rather of their trust in the findings of climate scientists, who are the experts? If the question was posed in such a way, would it show a much broader support in the science community for the acceptance of climate change and the need to act? Would this clarify the messaging to the public by separating a scientist's personal expertise from their support for the relevant experts? I guess one could just point to all the scientific societies that give the same supporting message on climate change, but maybe that could still be miscontrued by the public as a "top-down" opinion being pushed by representatives rather than an accurate reflection of the opinions of individual scientists.

23741. pjcarson2015 at 11:50 AM on 21 June 2016
       Climate scientists have warned us of coral bleaching for years. It's here
       

       1. Rob P: Are you doubting Valerie’s honesty? (Be careful in a public forum.) Are you sure there’s no footage? There are probably some around still. I remember seeing bleaching on film from about that time – probably the Taylors’, perhaps Cousteau’s – but such events were then seen as another unexplained natural phenomenon about which people weren’t jumping up and down. (Note Tom Curtis re 1965.)

       2. #10 Tom Curtis.

       As I quoted in #3, “I’ve seen reefs in PNG that were as white as snow …”

       indicates large scale – yet they recovered. Don’t be so selective in what you read.

       If high CO2 and temperatures caused these in 1965 (or even back to the 1920s according to Rob P), then how did they recover in higher CO2 (and therefore higher temperatures according to AGW)? Why do reefs bleach sporadically then recover?

       [“Sporadic” = occurring at irregular intervals or only in a few places.]

       Underwater observations of any sort were scarce before Cousteau’s innovations in the 1940s. The Taylors were among the pioneers of underwater documentaries, starting ca 1965. One can’t see bleaching if one’s not there, but the Taylors certainly saw extensive bleaching before the 1980s.

       3. Your statement “Undersea volcanic activity did not spike at that time, but sea temperatures did, and high sea temperatures are highly correlated with bleaching events.”

       You’ve no idea if that’s correct. Undersea volcanic activity has simply not even been observed let alone recorded until the past 10 (or less?) years. Even Black Smokers were first observed in the mid 1970s. They were a surprise that helped substantiate Wegener’s theory.

       4. Which high sea temperatures are you referring to, general or localised? It’s difficult to assign CO2 as the cause unless it’s general. The thermal stress graph in Rob P’s response to my #3 shows it is localised, albeit carried on ocean currents. Undersea volcanic activity produces toxins plus heat from magma, satisfying those criteria easily. Chapters 2 & 4 show it also matches the timing criteria.

       Moderator Response:

       [Rob P] If you have links to Taylor's film footage of GBR coral bleaching in 1965 then please share. If no footage exists, and given the lack of scientific evidence, such claims can be summarily dismissed.   

23742. william5331 at 06:31 AM on 21 June 2016
       2016 SkS Weekly Digest #25
       

       The solutions to the changing climate are pretty obvious.  A bunch of reasonably bright year 12 students could set out a game plan that would pretty well cover what we need to do.  The underlying critical probem that makes the whole thing like pushing the brown stuff up hill is the effect of money from vested interests on politicians.  It's not so much that they have been bribed and therefore do the bidding of their bribers.  It is that they know with certainty, if they don't do what they are told, they won't get the bribes next time.  It is not only support for their next election campaign that motivates them, but a cushy job when they leave office - often as a lobyist, continuing to corrupt politics.  It looks like we have just missed our last chance with Bernie.  This was his core  message.  Get big money out of politics.  It might just be too late.  Have you noticed what has happened to Carbon dioxide readings over the last few months - especially April to April.  4.16ppm.  I hope this is a laboratory error but not likely.

23743. 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.

23744. 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.  

23745. 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.

23746. 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.

23747. 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.
23748. 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.

23749. 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.

23750. 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).

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