Unforced Variations: May 2013

This month’s open thread.

551 comments on this post.
  1. sidd:

    Thank de lord.

    Attention: OT (On topic, as in climate science, feel free to ignore)

    1) DOI: 10.1002/grl.50456 McGrath et al.

    All of Greenland gets wet by 2025

    “Extrapolation of this observed trend now suggests, with 95 % confidence, that the dry snow facies of the Greenland Ice Sheet will inevitably transition to percolation facies. There is a 50 % probability of this transition occurring by 2025.”

    “There is a 50 % probability of the mean annual dry snow line migrating above Summit by 2025, at which time Summit will experience routine melt on an annual basis. The surface mass balance observations similarly indicate that the ELA has migrated upwards at a rate of 44 m/a over the 1997–2011 period in West Greenland, resulting in a more than doubling of the ablation zone width during this period…”

    Looking at a glacier, we got saturated snow low down where all of it melts every yr (saturated facies), partially wet snow (some melts every year, percolation facies) and dry snow hi up, never melts. They think that Summit will melt pretty much evry year

    0 C isotherm and ELA (equilibrium line altitude, above which glacier is in mass gain, and in mass waste below) rising by 35m/yr, 44m/yr. I think I have mentioned b4 that ELA went above the saddle at 67 N last year.

    They note that only half the runoff makes it outta there, rest refreezes, efficiently moving heat at 80 cal/g into the snowpack.

    Summit, apparently is warming faster than most other places on earth:

    “The observed 0.09 °C/a trend at Summit, six times the global average trend, ranks in the 99th percentile of all globally observed temperature trends over the climatology period (Figure 2 inset). We note, however, that the polar regions, where recent warming has been greatest, are overrepresented in the 9 % of the Earth’s surface for which observed temperature trends are not available. Thus, the observed global mean temperature trend, and the percentile rank of Summit, are likely biased towards lower and higher values, respectively.”

    2)Prof. Box updates Greenland albedo at meltfactor.org, notes lack of snowpack paving the way for more melt

    3) Park et al (doi:10.1002/grl.50379) point out that the lo end for Pine Island Glacier melt is too conservative, seeing that PIG hinge line retreats apace, tho the bedrock shoals and surface slope steepens. Apparently, the ocean eateth it from below faster than was thought.

    “Even though the Pine Island Glacier hinge-line has now migrated into the bedrock trough within which the main trunk of the glacier is seated, where basal slopes shoal and impede retreat, it is now retreating at a faster mean rate (1.8 ± 0.9 km yr-1) than at any time since it was first located … Our observations of accelerated thinning and ongoing rapid hinge-line retreat, coupled with the observed strengthening of ocean melting within the sub-ice-shelf cavity [Jacobs et al., 2011], suggest that the lower limit may be founded on a conservative forcing scenario…”

    Jacobs is a nice paper, showing how hot water worms under PIG.

    Any new news from Thwaites ? that one scares me more than PIG


  2. Bouke:

    I have a question regarding the mechanism behind the Hadley cell and thought I’d ask a real climate scientist.

    On the web Hadley cell air flow is explained as follows: “This flow of air occurs because the Sun heats air at the Earth’s surface near the equator. The warm air rises”. However, when I look at the average monthly surface temperatures for March, when the Hadley cell is directly above the equator, I see very little temperature difference between 30° and 0°. Therefore temperature difference can’t explain the effect. I can think of two alternative explanations:

    1: Surface temperatures may be almost the same, but higher up the tropical air is much warmer than the subtropical air. It is the average temperature of the entire troposphere air column that drives the Hadley cell.

    2: Tropical air is much more humid than subtropical air. Water vapor is much lighter than nitrogen (atomic mass of 18 vs 28), so it is this difference in density which drives the Hadley cell.

    Are these explanations correct?

  3. Chuck Hughes:

    I posted this link earlier and didn’t get a response so I’ll try it again on this open thread. So the question is…. if we make it to 450ppm CO2 in a couple of decades what then? I realize it’s an open ended question with no real answers but at what level of CO2 does the scientific community say, THAT’S IT! It seems to me that there’s no end in sight. What if we hit 500ppm? It looks to me like we’ll make it to that point without any trouble. What are you guys thinking about all of this? I would really love to hear Gavin’s opinion on what happens if we get to this point? I don’t know. I’m looking for an educated opinion. My daughter wants to know.


    Here are a few paragraphs from the article:

    “I wish it weren’t true but it looks like the world is going to blow through the 400ppm level without losing a beat. At this pace we’ll hit 450ppm within a few decades,” said Ralph Keeling, a geologist with the Scripps Institution of Oceanography which operates the Hawaiian observatory.

    The last time CO2 levels were so high was probably in the Pliocene epoch, between 3.2m and 5m years ago, when Earth’s climate was much warmer than today.

  4. prokaryotes:

    Get a sneak preview of the new ClimateState website, http://climatestate.com Focus is on embedded video streaming, users can submit content. Possibly the biggest climate science video platform to date.

  5. Pete Dunkelberg:

    Three items:
    Is your future wet or dry?
    Will the boiling cauldron bubble?
    Serendipitous musical interlude.

  6. Ray Ladbury:

    Gavin, sorry to extend the OT, but to correct some of Simon’s misimpressions, I thought I’d try one last time. Feel free to Simon, you evidently didn’t read what I wrote. I don’t think the evolution of life is a particularly rare phenomenon–the criteria you impose arbitrarily are just that–arbitrary.

    The thing is that distances (along with the theory of relativity) and radiation preclude interstellar travel, and it is unlikely that we will be able to pick up the ET version of Gilligan’s Island due to the weakness of the signal. As to a concerted effort to contact ET (or them to contact us), 1)it would still require a huge investment of energy that would be impractical for any civilization no matter how advanced, and 2)it might not be wise, given the possibility of intergalactic predatory species?

    The Universe could be teeming with life, but the distances preclude contact, especially out here on the exurbs of the galaxy.

  7. Ray Ladbury:

    Chuck Hughes,
    Saying “That’s it,” simply represents a failure of both imagination and determination to do the math. No matter how badly we screw things up, we will still have the ability to screw things up further–or to ameliorate them.

    A lot depends on climate sensitivity–on a variety of timescales. Arbitrary limits are arbitrary. All we can do is keep pushing in the right direction. You need to push so that your daughter still has the hope of making things better. She must push to preserve hope for her progeny. How is this different than the human condition we have always faced?

  8. JCH:

    Chuck Hughes says @ 3

    The anthropogenic component of atmospheric CO2 has been doubling in around 30 years. If that rate continues, which is a function of human behavior, we will hit 520 around 2043.

    400 – 280 = 120
    120 x 2 = 240
    240 + 280 = 520

    According to ExxonMobil, growing world demand can be met through 2040, at which time they report that only 1/2 of the world’s liquid fuels will have been burned. If energy companies can meet growing world demand, the 30-year doubling period shrinks.

  9. Lou Grinzo:

    Ray(7): I strongly agree, but I find this is a non-trivial challenge in climate communication, namely getting newcomers to understand that the current situation is quite urgent (current and locked-in emissions, long CO2 atmospheric lifetime, feedbacks, etc.) but that there’s still a huge range of possible future outcomes. I’ve run into this many times in my presentations: Show people the REALLY inconvenient truths, and then you have to pull them back from the edge and tell them, “No, that doesn’t mean we can just throw in the towel. It’s a rallying point, not an excuse for inaction.”

    I think of it in terms of the wedges mitigation analysis we all know, but in terms of impacts. Going into the future the range of impacts fans out until it becomes quite large, and the sooner we get serious about limiting our emissions, the better the outcomes we can still preserve.

  10. Russell:

    With the arrival of May, a new crop of science censors has sprung up at WUWT.

    [Response: Thanks for the link Russell. Tweeted (@MichaelEMann) :-) -mike]

  11. Ray Ladbury:

    Lou, The thing is that there are a broad range of outcomes that are predicated not just on the science, but also on our actions in light of that science. I think that the figure in the SPM showing impacts as a function of sensitivity and CO2 concentration (lots of pretty orange and red) is a good intro. Basically the outcomes could range from mild inconvenience to catastrophic collapse of human civilization and mass extinction. I think those are distinguishable in terms of preference.

  12. Ray Ladbury:

    Michael and Russell,
    Why do we care what the idiots think?

  13. Edward Greisch:

    1 Sidd: Thank you for the terrible news.

    3 Chuck Hughes: Read “Six Degrees” by Mark Lynas and “Under a Green Sky” by Professor Peter D Ward.

    8 Lou Grinzo: Communication? When is it pitchforks and torches time? WE are very serious. The problem is that the psychopaths in charge don’t care about anything at all. The psychopaths in charge are and have been a real threat to the community/civilization/human race for several decades already.

    “Moral Origins: The Evolution of Virtue, Altruism, and Shame” by Christopher Boehm
    “One of the biggest risks of group living is the possibility of being punished for our misdeeds by those around us. Bullies, thieves, free-riders, and especially psychopaths are the most likely to suffer this fate. Getting by requires getting along, and this social type of selection, Boehm shows, singles out altruists for survival.” Hunter-gatherer tribes use the death penalty in the case of really bad actors.

    6 Ray Ladbury: IF we can protect ourselves from radiation while living in space: “Radiation and Reason, The impact of Science on a culture of fear” by Wade Allison.
    Professor Allison says we can take up to 10 rems per month, a little more than 1000 times the present “legal” limit.
    If we manage to live in the Oort Cloud, we can move to the Centauri Cluster by moving a short distance in the year 35000 because Proxima Centauri will be inside of our Oort cloud at that time. We should be able to populate our whole galaxy within 64 million years by this method.

  14. Russell:


    Their antics are as edifying to observe today as when the Warden of Bedlam charged sixpence for the privilege.

  15. Andy Lee Robinson:

    6 @Ray
    “Why do we care what the idiots think?”

    genognosticide – peeing in the global knowledge pool to influence more idiots (voters) and hasten the destruction of civilization… not reason enough? :-)

  16. Andy Lee Robinson:

    correction, @12 !

  17. simon abingdon:

    #6 Ray Ladbury (ref #146 previous thread)

    Here I am. Sincere apologies for the unwitting possible misrepresentation. (A regrettable misuse due to a lacuna in my knowledge now remedied).

    You say “The Universe could be teeming with life”. But equally it might not be. There is no cast-iron evidence either way. Your argument is no more than an optimistic appeal to the mediocrity principle.

    In biological terms I am certain that intelligence is nothing more than a successful but random evolutionary survival trait, in principle no different from the spider’s ability to spin webs or the zebra’s cunning stripes.

    So as well as searching for extraterrestrial intelligence, a relevant academic exercise might also be to look for extraterrestrial giraffes or similar long-necked creatures, would it not? Well why not? Because you wouldn’t really expect to find any, would you? (But what fun if elephants were discovered on planet Zog).

    Ray please do not misunderstand me. If incontrovertible evidence for intelligent technological extraterrestrial life were found, that would be the most exciting thing that had ever happened in my life: but I’m not holding my breath.

  18. SecularAnimist:

    Chuck Hughes wrote: “… at what level of CO2 does the scientific community say, THAT’S IT!”

    That’s what?

    At any given level of CO2 there is a range of scenarios of what might happen, with varying probabilities, all depending on assumptions, unknowns and unknowables.

    What matters is that it is self-evident that the warming that has already occurred due to the current anthropogenic excess of CO2 is already having destructive, costly, and worsening impacts, and there is certain to be additional warming from that level of CO2, and adding more CO2 year is only going to make things much, much worse.

    What is needed is to phase out ALL anthropogenic CO2 emissions as rapidly as possible, with the steepest reductions occurring up front. There is plenty of low-hanging fruit — for example, eliminating the outright waste of more than half the USA’s primary energy production; using energy much more efficiently; and de-carbonizing electricity generation by replacing coal and gas with wind and solar. Other solutions, like electrifying most ground transport, and drastically reducing the GHG footprint of agriculture, will take longer, but that’s all the more reason to get started on them NOW.

    We also need to draw down the already dangerous anthropogenic excess of CO2, which can be done by sequestering carbon in soil and biomass with organic agriculture, reforestation, etc.

    We already know how to do this stuff (and we are learning more all the time). We already have the necessary tools and technologies at hand to make very large emission reductions very quickly.

    There are plenty of opportunities for individual action, and plenty more opportunities for engaging with political processes, and pressuring both governments and corporations, to bring about the policy changes needed to implement these solutions.

  19. SecularAnimist:

    Ray Ladbury wrote: “… distances (along with the theory of relativity) and radiation preclude interstellar travel … As to a concerted effort to contact ET (or them to contact us) … it might not be wise, given the possibility of intergalactic predatory species …”

    Um, if “interstellar travel” is “precluded”, then how can there be any possibility of “intergalactic predatory species”?

  20. Andy Lee Robinson:

    @17 Simon, it is still far too early to tell if intelligence is a successful survival trait.

    It may have helped to get where we are in a relatively limitless environment rich in resources and low in competition – but it’s collectively hopeless at avoiding what’s coming.

    As for other life in the universe, I can’t see how it isn’t evitable that it is teeming or has teemed with the stuff.

    Unfortunately we may never know. The chances of catching a glimpse are orders of magnitude more improbable than two spectators at a football match accidentally photographing each other’s camera flash from opposite sides of the arena, given that they only have enough juice for one flash each.

  21. Hank Roberts:

    > intergalactic predatory

    Interstellar, maybe; it’s possible to imagine targeting a relativistic rock at any detected signal that pops up within a few light years’ distance, as a paranoid way of keeping one’s stellar neighborhood quiet.

    Intergalactic, well, if them’s out thar, we’d probably see big signs and wonders in the heavens …

  22. simon abingdon:

    #20 Andy Lee Robinson “it is still far too early to tell if intelligence is a successful survival trait”

    Quite so. I meant “so far successful in homo sapiens”. I expect the natural world to continue flourishing long after we’re gone.

  23. SecularAnimist:

    Hank Roberts wrote: “if them’s out thar, we’d probably see big signs and wonders in the heavens”

    In Carl Sagan’s novel Contact, an ET from a multi-billion-year-old civilization tells SETI researcher Ellie Arroway that the Crab Nebula is the remnants of a failed engineering project.

  24. Chris Colose:

    #2 Bouke

    Actually, it can be shown pretty easily that an overturning circulation will develop given Earth’s radiative equilibrium temperature gradient (as a function of latitude). The Hadley cell is precisely what is so effective at homogenizing horizontal temperature gradients in the free troposphere. You can google “Weak Temperature Gradient approximation” for some literature on this.

    I don’t agree that water vapor is required to drive this cell. Latent heat release is certainly a critical part of tropical dynamics, but Hadley cell dynamics have been studied in the context of Mars, Venus, Snowball Earth, etc, which largely operate in the dry dynamical limit.

    The horizontal extent of the Hadley cell is determined to a large extent by planetary rotation rates. If the Earth rotated much slower, the Hadley cell would extend to the poles and free tropospheric temperature gradients would be much harder to sustain everywhere. As it is, a Hadley cell that conserves angular momentum develops large wind shears and the flow becomes baroclinically unstable (it can be shown through the so-called thermal wind equation that the vertical gradient of the horizontal wind velocity is proportional to the horizontal temperature gradient). On Earth this happens close to 30 degrees latitude, and poleward of this the heat transport is dominated by mid-latitude eddies rather than being under the wings of a giant overturning circulation (you can still find references to a mid-latitude “Ferrell cell” in textbooks, but this is not a good description of what happens).

  25. simon abingdon:

    #20 Andy Lee Robinson

    “I can’t see how it isn’t [?in]evitable that it is teeming or has teemed with the stuff”.

    Come on Andy, look closer to home. Not much evidence yet of teeming going on in Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune or poor old Pluto.

  26. Jim Galasyn:

    Re extraterrestrial life, it seems likely that bacterial slime is ubiquitous, anywhere there’s liquid water and rock.

    Complex multicellular life may be much more rare. I asked Peter Ward if the various Earth-like exoplanets we’re discovering will be predominantly “purple Earths” (anoxic, microbial) or “blue Earths” (oxic, multicellular), and he said we’ll find mostly purple Earths.

  27. Shelama:

    We know that Homo sapiens will eventually go extinct in great misery. It won’t be due to AGW and it doesn’t particularly matter what it will be due to instead.

    And it doesn’t really matter whether it happens in 4K, 4M or to some poor schmuck and his family 4B years from now.

    The way I see it, this is a terrific once-in-an-Earthtime experiment and we should burn fossil fuels as fast, furious and completely as we can. Just to see what happens.

    We’re pretty much going to do just that anyway.

    At least some of us will get to say, “I told you so,” and enjoy the schadenfreude of hearing Watts admit he was not only wrong but stupid.

    In the end, it all turns out the same.

  28. Chris Korda:

    I just waded through Hansen et al.’s latest (unreleased) Climate Sensitivity, Sea Level, and Atmospheric CO2, and it seems clear enough but I just want to be sure I’m not missing something. My takeaway: Fast feedback sensitivity is at least 3ºC per 2 x CO2 and likely closer to 4º. And, current ice sheet models exhibit implausible hysteresis (they’re too lethargic), i.e. SLR is likely to happen much sooner than expected. Ouch. Guess I should update my RCP temperature graphs for 4º; will do so in a future post.

    “we conclude that this relatively clean empirical assessment yields a fast feedback climate sensitivity in the upper part of the range suggested by the LGM Holocene climate change, i.e., a sensitivity 3 – 4°C for 2×CO2” (p. 23)

    “Altogether, the empirical data support a high sensitivity of sea level to global temperature change, and they provide strong evidence against the seeming lethargy and large hysteresis effects that occur in at least some ice sheet models.” (p. 22)

  29. prokaryotes:

    Two videos which caught my attention recently…

    Jennifer Francis: Wacky Weather and disappearing Arctic Sea Ice are they connected? http://galaxymachine.de/2013/05/04/jennifer-francis-wacky-weather-and-disappearing-arctic-sea-ice-are-they-connected/

    Kevin Trenberth: How To Relate Climate Extremes to Climate Change http://galaxymachine.de/2013/05/04/kevin-trenberth-how-to-relate-climate-extremes-to-climate-change/

  30. Pete Dunkelberg:

    Jeeze Simon, teeming is relative in this business. One planet out of eight is pretty good, and there lots of planets, moons and comets in the solar system that either have hardly been explored or won’t be warm enough until later when the sun starts expanding into red giant-hood.

  31. Chris Korda:

    The way I see it, this is a terrific once-in-an-Earthtime experiment and we should burn fossil fuels as fast, furious and completely as we can. Just to see what happens.

    An experiment usually implies that the result is unknown, or at least sufficiently in doubt to be worth verifying. In this case it’s not much of an experiment since the outcome has already been determined in excruciating detail for anyone who cares to read. Also your claim that human extinction “won’t be due to AGW” seems to require justification. In fact evidence for the opposite conclusion is abundant; see e.g. the Hansen et al. paper referenced above @28, or in more casual language, Hansen’s recent missive in which he states: “But it is not an exaggeration to suggest, based on best available scientific evidence, that burning all fossil fuels could result in the planet being not only ice-free but human-free.” (p. 6)

  32. Patrick:

    @13.6 Welcome to the science fiction convention. This lip-stick-on-the-radiation effort is all too similar to the recent one on CO2. I’ll take the consensus numbers or lower and the retired prof you cite will not say what I can take. Sufficient unto the day is the radiation thereof (sorry).

  33. Patrick:

    @9 Thank you for your service in the communication of climate science.

  34. Titus:

    Jim @26 Re bactirial slim.

    This stuff is mind bogglingly complex. Did a very quick search and came up with following:

    I’m sure knowledgable souls could elaborate. Not the sort of stuff of spontaneous generation me thinks and would make multicellular stuff a breeze in comparison.

  35. Jim Galasyn:

    tTitus says: Not the sort of stuff of spontaneous generation me thinks and would make multicellular stuff a breeze in comparison.

    I don’t want to trivialize the problem of abiogenesis, but it’s my suspicion that because matter self-organizes in the presence of energy, the phase of matter we call “life” will appear everywhere it’s possible, not as a singular event, but continuously across the galaxies. One might see it as the “continuous creation” hypothesis versus the “Big Bang”.

    I’m eagerly waiting for the first spectra from some of the newly discovered exoplanets, so maybe we can infer biochemical signatures and test theories of abiogenesis.

  36. Ray Ladbury:

    It is probably the galactic cosmic rays that preclude interstellar travel for our own species. High atomic number (Z), high energy (E)–so-called HZE ions can take out large amounts of genetic information, zapping both strands of our redundant code. In part, that could be the result of our having evolved in a fairly low radiation environment. Other life forms evolving in higher-radiation environments might be expected to have greater and more robust redundancy, and so would be more suited to interstellar travel.

    Simon, I agree that there is no evidence either way, but I would contend that is precisely what would be expected–there’s no paradox to the Fermi Paradox.

  37. Susan Anderson:

    Nice useful shorter (16 minutes) Jennifer Francis, very clear and accessible, fwiw:

    “Does Arctic Amplification Fuel Extreme Weather in Mid-Latitudes?”

  38. Kevin McKinney:

    “In the end, it all turns out the same.”

    Sure. That’s why the middle is so much more interesting, and why we should strive to conserve it.

  39. Edward Greisch:

    32 Patrick & 36 Ray Ladbury: Look up “Natural Background Radiation.” After that see:

    The background where you are sitting is higher than the background + the reactor leak in Fukushima if you are in most places.


    And check out how much uranium and arsenic there is in coal:

    Remember that this planet was made from the debris of a supernova and billions of years ago, the background was much higher than it is now. Check out Ramsar, Iran.

  40. Russell:

    23, 32

    Thank you for reminding us that Carl recycled more science fiction than many realize.

  41. Johnno:

    Watching a farming show on Australian TV it seemed to me that words were getting new meanings, something George Orwell warned us about. Specifically
    drought = not La Nina
    Grain growers on the edge of areas flooded in recent years did OK. Now they want that every year too bad about the floods. In other words rainfall in normal years is now below expectations.

  42. Dave Peters:

    Re: Prokaryotes 4 May, 4:51 PM, reference to “wacky weather” talk;

    I once attempted to explain the potential, that decades into the future it might not be possible to reliably predict regional implications of gross climate alteration, by drawing the analogy to the difficulty of comprehending the precise path of a smoke particle, as a plume broke from laminar to turbulent flow. I am uncertain of the propriety of reference to non-reviewed articles here, but perhaps an exception could be made for Randal Simpson’s rare, knee bone connected to the thigh bone assault upon the mechanical causality of sudden stratospheric warmings, and associated teleconnections. Such as the snow on my deck here in south Colorado, yesterday. As pure who done it entertainment, his post is a hoot.


  43. prokaryotes:

    How many civilization are out there which caused a warm climate shift or runaway state? From the amount of advanced species, many might initiate a climate shift. Maybe the reason why we have made no contact with ET yet is because they see what is going on with our climate. “A failed planet…”

  44. Kevin McKinney:

    “Why do we care what the idiots think?”

    Perhaps we don’t, so much, but we are forced to some degree to care what they say–perceptions of idiocy (or its reverse) being somewhat variable among independent ‘raters.’

  45. Kevin McKinney:

    “…it is still far too early to tell if intelligence is a successful survival trait.

    “It may have helped to get where we are in a relatively limitless environment rich in resources and low in competition – but it’s collectively hopeless at avoiding what’s coming.”

    Prejudging the outcome a bit, aren’t we?

    Anyway, many more parameters determine human behavior than the undefined (and almost certainly not unitary) quality termed ‘intelligence’. Notionally, we are no more intelligent than, say, the ancient Sumerians, yet our behavior is quite different in many ways. Maybe not enough to pass the test we are collectively facing, but it’s far too early to quit trying.

  46. James Cross:


    Ray, the Fermi Paradox really doesn’t require that organisms travel in interstellar space. Advanced civilizations could send machines.

    A better explanation would be that intelligent life is only now appearing in the universe so there hasn’t been enough time for it to reach us.



  47. Thomas Lee Elifritz:

    Re : Fermi Paradox, most modern thinkers now think in terms of ‘directed panspermia’. You don’t even have to send a machine, that comes later, all you have to do is send a seed for the oceans. In that case they are already here and they is us. Regardless, once they show up they’re just going to clone us and then they will be us as well, just more advanced versions of us.

    Believe it or not there is evidence to support this hypothesis as well as ‘directed abiogenesis’, because presumably the laws of our local physics evolved into being as well, and apparently does not prohibit non-local physics either.

  48. SecularAnimist:

    There just isn’t any real “paradox” in the Fermi Paradox.

    If you assume that civilizations at least as technologically advanced as our own are abundant in the galaxy, and then start making a list of the pretty obvious reasons why we might not be able to detect their existence by any of the means presently available to SETI research, it very quickly becomes a long list. No paradox. And certainly no “moral of the story” that implies any particular fate for the human species.

  49. SecularAnimist:

    Also regarding the Fermi “Paradox”, consider that “technologically advanced” doesn’t necessarily mean what most people assume it means.

    I recall a story by Heinlein (I think) in which human explorers arrived on Venus to discover a VERY technologically advanced civilization whose existence had been unsuspected from Earth.

    It turned out that the Venusians were highly advanced in bioscience (as one of the explorers put it, “they have forgotten more about organic chemistry and genetics than we’ll ever know”) and had biotechnology “indistinguishable from magic” — all of their “technology” consisted of living organisms, or materials produced by living organisms. But they had never developed metallurgy, or the use of electromagnetic radiation, so their civilization was “silent” since it emitted no signals into space.

  50. Ray Ladbury:

    The interstellar galactic cosmic radiation environment is roughly 3 times worse than that within the solar system. Travel times to the nearest star that might harbor life would likely be measured in millennia, and it is difficult to envision a technology that would be sufficiently lightweight, capable and reliable to survive such a mission. And again, if you were to send a robot, would you send it toward the exurbs of the galaxy or toward the center, where stellar densities are much higher. The paradox in the Fermi paradox is why anyone would expect such an insignificant, isolated planetary to have been high on the list for contact.