There has been an unusual surge of interest in the climate sensitivity based on the last decade’s worth of temperature measurements, and a lengthy story in the Economist tries to argue that the climate sensitivity may be lower than previously estimated. I think its conclusion is somewhat misguided because it missed some important pieces of information (also see skepticalscience’s take on this story here).
While the Economist referred to some unpublished work, it missed a new paper by Balmaseda et al. (2013) which provides a more in-depth insight. Balmaseda et al suggest that the recent years may not have much effect on the climate sensitivity after all, and according to their analysis, it is the winds blowing over the oceans that may be responsible for the ‘slow-down’ presented in the Economist.
It is well-known that changes in temperature on decadal time scales are strongly influenced by natural and internal variations, and should not be confused with a long-term trend (Easterling and Wehner, 2009;Foster and Rahmstorf, 2011).
An intensification of the trades has affected surface ocean currents called the subtropical gyres, and these changes have resulted in a predominance of the La Nina state. The La Nina phase is associated with a lower global mean temperature than usual.
Balmaseda et al’s results also suggested that a negative phase of the pacific decadal oscillation (PDO) may have made an imprint on the most recent years. In addition, they found that the deep ocean has warmed over the recent years, while the upper 300m of the oceans have ‘stabilised’.
The oceans can be compared to a battery that needs to be recharged after going flat. After the powerful 1997-98 El Nino, heat flowed out of the tropical oceans in order to heat the atmosphere (evaporative cooling) and the higher latitudes. The warming resumed after the ‘deflation’, but something happened after 1998: since then, the warming has involved the deep ocean to a much greater extent. A weakening of the Atlantic meridional overturning circulation (MOC) may have played a role in the deep ocean warming.
The recent changes in these decade-scale variations appear to have masked the real accumulation of heat on Earth.
The new knowledge from this paper, the way I read it, is the revelation of the role of winds for vertical mixing/diffusion of heat in a new analysis of the world oceans. Their results were derived through a set of different experiments testing the sensitivity to various assumptions and choices made for data inclusion and the ocean model assimilation set-up.
The analysis involved a brand new ocean analysis (ORAS4; Balmaseda et al., 2013) based on an optimal use of observations, data assimilation, and an ocean model forced with state-of-the-art description of the atmosphere (reanalyses).
By running a set of different experiments with the ocean model, including different conditions, such as surface winds and different types of data, they explored which influence the different conditions have on their final conclusion.
The finding that the winds play a role for the state of the warming may not be surprising to oceanographers, although it may not necessarily be the first thing a meteorologist may consider.
Other related discussions: OSS
References
- M.A. Balmaseda, K.E. Trenberth, and E. Källén, "Distinctive climate signals in reanalysis of global ocean heat content", Geophysical Research Letters, vol. 40, pp. 1754-1759, 2013. http://dx.doi.org/10.1002/grl.50382
- D.R. Easterling, and M.F. Wehner, "Is the climate warming or cooling?", Geophysical Research Letters, vol. 36, 2009. http://dx.doi.org/10.1029/2009GL037810
- G. Foster, and S. Rahmstorf, "Global temperature evolution 1979–2010", Environmental Research Letters, vol. 6, pp. 044022, 2011. http://dx.doi.org/10.1088/1748-9326/6/4/044022
- M.A. Balmaseda, K. Mogensen, and A.T. Weaver, "Evaluation of the ECMWF ocean reanalysis system ORAS4", Quarterly Journal of the Royal Meteorological Society, vol. 139, pp. 1132-1161, 2012. http://dx.doi.org/10.1002/qj.2063
Titus,
A suggestion–doubt based on ignorance of biology is not a valid basis for judging a scientific theory of life, just as ignorance of how the greenhouse effect works is not a basis for judging climate science.
Evolution is a fact. This has nothing to do with the origin of life. However, the research there also suggests that abiogenesis is the likely origin of life.
Independent confirmation of global land warming without the use of station temperatures
http://onlinelibrary.wiley.com/doi/10.1002/grl.50425/abstract
DOI: 10.1002/grl.50425
Nagel’s latest book was reviewed last winter by H. Allen Orr in New York Review of Books, February 7 issue. Well worth a read (the review). At risk of going beyond the theme of this thread, I offer up excerpts from it because I think Orr’s review speaks indirectly to the larger issue of how we as humans and as a global society are reacting to the findings of the earth sciences regarding anthropogenic global warming, climate disruption, and their ensuing ecological and socio-economic consequences:
With regard to whether the idea of mind “poses some insurmountable barrier to materialism,” Orr makes two points:
1)
“Science has, since the seventeenth century, proved remarkably adept at incorporating initially alien ideas (like electromagnetic fields) into its thinking. Yet most people, apparently including Nagel, find the resulting science sufficiently materialist.”
2)
“. . . [T]here might be perfectly good reasons why you can’t imagine a solution to the problem of consciousness. As the philosopher Colin McGinn has emphasized, your very inability to imagine a solution might reflect your cognitive limitations as an evolved creature. The point is that we have no reason to believe that we, as organisms whose brains are evolved and finite, can fathom the answer to every question that we can ask. All other species have cognitive limitations, why not us? So even if matter does give rise to mind, we might not be able to understand how.”
The conclusion of Orr’s review:
“The question, then, is not whether teleology is formally compatible with the practice of science. The question is whether the practice of science leads to taking teleology seriously. Nagel may find this question unfair. He is, he says, engaging in a “philosophical task,” not the “internal pursuit of science.” But it seems clear that he is doing more than this. He’s emphasizing purported “empirical reasons” for finding neo-Darwinism “almost certainly false” and he’s suggesting the existence of new scientific laws. These represent moves, however halting, into science proper. But science, finally, isn’t about defining the space of all formally possible explanations of nature. It’s about inference to the most likely hypothesis. And on these grounds there’s simply no comparison between neo-Darwinism (for which there is overwhelming evidence) and natural teleology (for which there is none). While one might complain that it’s unfair to stack up the empirical successes of neo-Darwinism with those of a new theory, this, again, gets the history wrong. Teleology is the traditional view; neo-Darwinism is the new kid on the block.
“None of this is to suggest that evolutionary biology will not, someday, change radically. Of course it might; any science might. Nor is it to suggest that materialism represents some final unassailable view and that teleology or, for that matter, theism will inevitably be spoken of in the past tense by many scientists. It is to say that the way to any such alternative view will have to acknowledge the full powers of present science. I cannot conclude that [Nagel’s book] does this.”
Finally, regarding neuropsychology’s 100+ year exploration of consciousness and mind: see S. Pinker’s wonderful book, How the Mind Works.
Thanks for answers: Now that I know the right question to ask, yes, fresh water is densest at ~4 deg C (why calm lakes freeze suddenly, etc), but sea water basically always has a positive coefficient of thermal expansion. Bottom line for scientific amateurs: heat energy added to the oceans will give you expansion and higher sea levels, without worrying about various ocean temperatures. (There are details about temperature, salinity, and so forth.) This very fact explains why I hadn’t seen references to the 4-degree threshold in general discussions of global warming and sea level.
Wow. Thanks for the attention.
Peter D – Thanks for those two interesting articles on Nagel. I had not seen them.
Hank R – No apology for the language. I think the imagination is a great tool. Where would we be without out it?
Ray L – Abiogenesis has settled nothing to my knowledge. Lots of folks with ideas and ‘imaginations’.
BTW: I enjoyed reading the artlical on Fourier, especially the historical links. Very interesting.
Turning ice into water sucks up a lot of energy. Therefore, water and ice at near the same temperature have very different energy content. So wouldn’t you expect ice melt to result in lower temperatures? Isn’t that what happens in a glass of scotch?
“It’s not the trolling, it’s the biting.”
— Marion Delgado, June 6, 2008, at Deltoid
Calls for science to incorporate teleology or other non-material causes are up against a core principal of science, namely intersubjective verifiability. Unless an observation can be reliably and accurately reproduced by other disciplined observers, it can’t be distinguished from an illusion, a hallucination, or a misguided interpretation of an ambiguous signal; it has no claim to consideration as a fact.
Assuming a verifiable set of facts, competing hypotheses that attempt to explain them are up against peer review. Nagel may claim that “empirical evidence” shows neo-Darwinism to be “almost certainly false”, but unless he can convince a majority of evolutionary biologists of that, he’s just another guy making unsupported claims. As a non-scientist, I’m not going to waste my time on him. I’ll stick with the expert consensus.
Mal Adapted wrote: “Unless an observation can be reliably and accurately reproduced by other disciplined observers, it can’t be distinguished from an illusion, a hallucination, or a misguided interpretation of an ambiguous signal; it has no claim to consideration as a fact.”
Of course, that is the basis upon which hard-core behaviorists deny the existence of subjective experience.
I think Sloop’s excerpts & summary of Orr’s review of Nagel’s book exemplifies why such discussions are usually so unfruitful — participants bring to them a jumble of ill-defined notions, sloppily conflated ideas, and dogmatic views.
So often I see these kind of discussions bring out the worst in both “sides” (and people almost always wind up “taking sides”).
Based on the “arguments” typically presented, one would think that on the “science side” science has not progressed beyond naive 19th century mechanistic materialism, and on the “philosophy side” that the be-all and end-all of thinking about the nature, arising and role of mind in the universe is 1st century Middle Eastern monotheism.
The “debate” over whether the world is a dead machine set in motion by random accidents or a dead machine remote-controlled by the God of Abraham is about as barren as it gets.
“Abiogenesis has settled nothing to my knowledge. Lots of folks with ideas and ‘imaginations’.”
And some folks with interesting experimental evidence. You may wish to consider same while partaking of the amino acids from your grocery store that your body turns into ‘Titus”.
[CAPTCHA says they’re ‘gyvingli bars’, maybe organic]
#101 Ray Ladbury “Evolution is a fact. This has nothing to do with the origin of life. However, the research there also suggests that abiogenesis is the likely origin of life.”
Ray, the emergence of life appears to be less than widespread in the knowable universe (at least as it has so far been observed). So “Abiogenesis is the likely origin of life” is an unwarranted presumption.
Religions have sought an explanation for the emergence of life and they have failed ludicrously and abysmally. Most thinking people now realise that science is probably the only discipline which could possibly enable us to understand how to explain such a deep and so-far unknowable truth.
So is it not high time for science to start thinking outside the box of its much lauded and justly revered enlightenment?
Hank @100
Chris Smither sings about “evolution is not something you believe in. It’s just something you know about”.
We should also remember the sage advice “knowledge is not understanding”.
MA @#107:
Read all of Orr’s essay. It is far from uniformly condemning Nagel’s latest treatise. And Nagel is certainly not “just another guy making unsupported claims.”
Titus @#105:
I suggest that you too quickly dismiss the work underway along this fascinating scientific frontier. Progress has definitely been made via numerous hypotheses and much intriguing evidence. The search is far from over, but I’ll grant that you appreciate how that is not itself evidence for the existence of a cosmic diety.
Meta: Please can we have a “Unforced Variations That Have Nothing To Do With Climate” thread.
I was under the (apparently mistaken) impression that this was a climate site, and this thread was about ocean heat content.
sidd
simon abingdon wrote: “Ray, the emergence of life appears to be less than widespread in the knowable universe (at least as it has so far been observed).”
Really? When did we develop the ability to detect the presence or absence of bacteria on extra-solar planets? I must have missed that.
simon abingdon wrote: “Religions have sought an explanation for the emergence of life and they have failed ludicrously and abysmally.”
It’s interesting to note that when the Buddha was asked about the origin of life, his response was that the world of living beings had “no discernable beginning”. Which was an accurate characterization of the available empirical evidence 2500 years ago.
“Ray, the emergence of life appears to be less than widespread in the knowable universe (at least as it has so far been observed). So “Abiogenesis is the likely origin of life” is an unwarranted presumption.”
For all practical purposes, none of the universe has been observed with instruments that can detect the presence or absence of life. In fact, from this point of view, not even our own solar system has been thorougly observed.
You’re arguing, essentially, from personal incredulity.
Titus @#112
With all due respect, your aphorism strikes me as facile and a bit muddled.
To compensate partially for my participation in the hijacking of this thread, I point to how Rhode Island’s coastal zone management (CZM) agency, the RI Coastal Resources Management Council (CRMC) is addressing current and future sea-level rise (SLR). It is about to incorporate an expanded SLR policy into its federally-approved CZM Plan and has begun a special area management planning process (SAMP) that will entail in-depth research on shoreline erosion rates, coastal sediment flows and regimes, modeled shoreline inundations, and then engagement with towns and Rhode Islanders to help them digest (knowledge is definitely essential to understanding) the consequences of those findings for coastal development, erosion management, and natural hazard response and recovery.
CRMC’s SLR Policy projects 3-5′ of SLR along the RI coast by 2100. It is thoroughly justified by and built from references and analysis of recent climatological and oceanographic findings, including the weakening of the Atlantic MOC apparently noted in the Balmaseda et al paper discussed in this post. It mandates that all future CZM decisions in RI account for this level of overall inundation. Furthermore, the CRMC possesses nationally unique authorities to regulate development along RI’s shoreline and within the state’s marine waters.
The CRMC Shoreline Erosion SAMP was launched this spring and will continue for three years. It is a compelling, still unfolding model and case study for study by students of US CZM.
The work of this agency (and state) is a welcome, alternative model to policies recently legislated by North Carolina regarding the relevance and applicability of scientifically based SLR projections to coastal development planning and management. Rhode Island is not an island (as many Americans assume); but it is a city state wrapped around an estuary. Its entire geography is a coastal watershed. Hence, it takes the promise, abundance, and risks posed by the ocean very seriously.
> “knowledge is not understanding”
Exactly. That’s your petard.
Knowledge enables us to make policy decisions.
We know what happens, without (yet) understanding all the mechanisms, without understanding all of the details.
And that’s enough. The “must be a hidden cause somewhere we haven’t looked yet” gaps get narrower and narrower. We never understand everything.
Nevertheless, we know.
Recall the tobacco companies’ argument against regulation:
“… while statistics overwhelmingly convicted tobacco as a cancer causing substance, there was no known mechanism by which it caused cancer….”
“Observed warming is inconsistent with climate models that do not incorporate human greenhouse gas emissions, but consistent with those that do.”
And we’re back on topic!
We know (some of) the deep ocean is warming.
We understand (some of) what changed, and how, and when, in the past.
Revisiting the Meteor
1925–27 hydrographic dataset reveals centennial full-depth changes in the Atlantic Ocean
DOI: 10.1002/grl.50503
Plenty more where that came from.
Aphorism and Petard aye? Well, this is a blog after all and I’m conscious of taking it off topic. I never intend this.
Sloop: I counld’t agree more with the work that you are engaged in. I followed the building of the Thames Barrier in London which was an incredible feat of engineering based on the then latest knowledge and understanding. IMO this needs to be done all the way down the US East Coast, the Outer Banks NC especially look at great risk. Not to mention consequences of NY.
Hank: As with my reply to Sloop I’m all for scientific knowledge having input into political decisions.
And thanks for getting us back on topic!!! I’ve actual learnt a lot. Including my new word ‘advection’
Thanks……..
Titus,
They find many of the building blocks of life even in cosmic dust. Laboratory experiments have produced more complex building blocks under conditions thought to persist on early Earth. Each new experiment continues to add to understanding.
So to you and Simon, I would ask, why “think outside the box” when the scientific method is producing steady progress, as it should?
Well there’s been talk of evolution and origin of life (OOL). Life clearly did and does evolve. It also started early in earth’s history, although the details still elude us. Conveniently, the current issue of Nature Chemistry is on it. How long does it take? We know it didn’t take too long, and no one in science supposes it happens immediately. For all we know though, when a young planet freshly coated with cometary organics reaches the right temperature it may take just a thousand years. So why hasn’t it all been worked out? Because no university allows you that long to finish your dissertation.
I don’t mean to be rude, though I likely accomplished it above.
Sorry, been grouchy for days about nothing related to the conversation. I see I leaked crankiness there.
sidd, back on topic for you. You have heard that once heat is dissipated into deep water, it can’t come back to bite us. But it may still change the surface environment as follows: Large currents depart the poles. The global current maps make it look as though the same water keeps circulating. But of course the currents lose water to general mixing along the way. That’s what keeps the deep oxygenated. So new water must enter the currents, primarily at the polar descent points. So the Southern Ocean around Antarctica advects in Pacific water to replace what goes out the bottom. And this water is hotter than it used to be, and melts ice, pushing the Pine Island glacier back thirty kilometers IIRC.
I opine that abiogenesis is not entirely off-topic for Real CLimate. After all the paleoclimatology of pre-biotic Terra was probably rather different and, at least, the time of abiogenesis is of importance to paleoclimatology.
I will recommend the (rather difficult) book, “The Logic of Chance” by Eugene Koonin. Here is a sample two part review
http://ofbacteriaandmen.blogspot.com/2012/09/the-logic-of-chance-by-eugene-koonin.html
http://ofbacteriaandmen.blogspot.com/2012/09/the-logic-of-chance-by-eugene-koonin_22.html
which fails to consider the appendix. In the appendix Dr. Koonin estimates the probability of abiogenesis. In his estimation it is indeed a tiny number. His solution is to then posit a multiverse. I suppose dicussion of that is indeed off-topic here at Real Climate.
OT alert:
Simon wrote: “Ray, the emergence of life appears to be less than widespread in the knowable universe (at least as it has so far been observed). So “Abiogenesis is the likely origin of life” is an unwarranted presumption.”
If there is any logical connection between the two sentences quoted above, it escapes me. The statistical frequency of life in the universe says nothing about abiogenesis versus divine creation or any other alternative ‘myth’ you may construct–at least until the actual pathway[s] by which abiogenesis takes place can be traced in sufficient detail to calculate probabilities.
People have taken some generalized stabs at this, I know, but I doubt that anyone can claim anything like rigor in such calculations.
Thank you Mr. Roberts for the reference to Gouretski(2013), I always look forward to deep ocean measurements. I am intrigued by their finding that since the 1920s the deep Atlantic below 2000m exhibited slight cooling and freshening. I have a suspicion that the trend has changed to warming lately (Purkey,Kouketsu,Johnson…) although the freshening (a la von Shuckman) might yet persist.
http://www.pmel.noaa.gov/people/gjohnson/gcj_3w.pdf
sidd
i wonder what the thermodynamic properties of large amounts of suspended solids would be on vertical circulation and heat retention . it would seem reasonablre that there should be a discernable effect.
T. Kukulka, G. Proskurowski, S. Morét-Ferguson, D. W. Meyer, K. L. Law. The effect of wind mixing on the vertical distribution of buoyant plastic debris. Geophysical Research Letters, 2012; 39 (7) DOI: 10.1029/2012GL051116
Here’s the correct link for what we know is (and isn’t) consisten with the observed warming so far
#126 Kevin McKinney
The logical connection between the paucity of the data and “abiogenesis is the likely origin of life” being an “unwarranted presumption” is manifest. Note (for example) #125 David B. Benson “Dr. Koonin estimates the probability of abiogenesis. In his estimation it is indeed a tiny number”. To prevent such escapes in future do not relax your grasp.
Kevin (#127),
Abiogenesis is usually put in opposition to exogenesis, a less grand panspermia-type theory. The advantage of panspermia (which a pared down version largely loses) is that it vastly opens up the time and volume over which abiogenesis can occur. It is a sort of infinite monkeie with infinite time and infinite typewriters approach to writing the works of Shakespeare-type solution to the problem of getting life to come into existence as quickly as it did on Earth. Both theories exclude divine intervention. http://en.wikipedia.org/wiki/Abiogenesis#.22Primitive.22_extraterrestrial_life
Simon,
I think your assertion that there is a paucity of life in the Universe is unfounded. I’m curious what evidence you are relying on for that conclusion. Or put another way, what evidence would you expect to see if the Universe were teeming with life?
Interstellar distances are sufficiently large to explain the lack of “visitors”. And if aliens were trying to contact other life forms (which they might not be, given the possibility that there might be predatory aliens out there), they would probably not be broadcasting broadband, but rather directionally due to the huge power demands of interstellar transmission. And why would they send signals toward us out in the exurbs of the galaxy rather than toward the galactic center?
What is more, our own experience indicates that any civilization capable of sufficiently advanced technology to make its presence known would capable if not likely to destroy itself. The Fermi Paradox is a paradox only if you don’t believe in relativity or if you ignore human experience.
sidd wrote: “I was under the (apparently mistaken) impression that this was a climate site, and this thread was about ocean heat content.”
Well, given the title of this thread, it’s not surprising to find commenters blowing wind and going off the deep end.
David Benson 2 125, “Koonin … tiny number”
Yes, there is a general way to get such numbers.
Start with a thimble full of air. The exact arrangement of molecules in that thimble is wildly improbable. But generically, the thimble being full of air is extremely probable. That’s hint 1: to get beyond “Everything’s improbable, in the usual way” you need to look at general types of outcomes.
Next, the air in the room. Will it all move to one corner? No, even though that is a general type of event, not a specific molecular arrangement in the corner. Will just all the oxygen go to one corner? No. How about just all the water vapor? No again. But go outside and look up. OMG clouds! that’s almost impossible! How could it happen? Well, there is a cloud-forming process in nature. No multiverse needed. When you learn the cloud forming process, you can make a reasonable estimate of their probability, even though the exact details of any particular cloud will still seem extremely unlikely. Just about everything in nature is the result of some process, and to estimate the probability you need to look a both a type of outcome and the process.
Back to Koonin. I don’t have that book but I think he sees this problem: To get a basic life form working (including natural selection) you need very good (but not perfect) replication. But, he says, you needed replication and selection to arrive at that point in the first place. He does not see a process that solves this “chicken and egg” problem. And without the process, surprise! he gets that tiny number. A number arrived at by this method is the probability that you used the right process.
Koonin has certainly done a lot of good research in moloecual biology. It would not be unique though if that turns out not to guarantee “big idea” argumentative papers. Note that researches have not decided to quit, and steady step by step progress continues. Note that in addition to various pre-RNA World possibilities, there are also non-RNA possibilities (Wachterhauser, Kaufman (those two should get together)).
Without the process, the best estimate of the probability is to note that it didn’t take too long on earth.
#132 Ray Ladbury “what evidence would you expect to see if the Universe were teeming with life?”
Ray, depending on how you define “life” I’m pretty sure that the solar system is pretty well devoid of life apart from here.
I dismiss the possibility of intelligent life elsewhere in the universe on the simple grounds of improbability. There are just not enough stars to combat the formidable odds against.
I believe 1000^8 is a generous estimate for the number of stars in the visible universe, so if we find that we can identify more than 8 independent 1/1000 conditions needed for the evolution of intelligent (technical) life then it looks like we’ll have run out of candidate stars other than the sun and may count ourselves very fortunate to have beaten the staggering odds against being here at all.
For starters here’s an outline menu for a candidate planet: (1) Orbit nearly circular and stable for billions of years, (2) Surface mainly water with corresponding temperatures, (3) A large moon keeping our tilted axis stable, (4) A large defensive outer planet such as Jupiter.
And as far as intelligent life (as we know it) is concerned: (5) A timely extinction paving the way for mammalian life forms, (6) Eventual evolution of bipedalism and the opposable thumb, (7) Discovery of fossil fuels and the control of fire, (8) Development of agriculture and civilisation, (9) An industrial revolution leading to the mastery of technology.
One could easily refine these lists and think of dozens of other unlikely fortuities.
If we give each of the nine occurrences above a less than 1 in 1000 chance of happening for a given planetary system, it looks like we just ran out of stars.
And the answer to Fermi’s “where are they?” turns out to be “they just ain’t anywhere”.
“Dr. Koonin estimates the probability of abiogenesis. In his estimation it is indeed a tiny number”
The probability of the single planet Earth, among the unimaginable number of bodies in the universe, evolving to what it currently is . . . is at most an even tinier number. The probability that a single [conscious? intelligent? aware?] species on the planet Earth will be the cause of it’s demise is a very much larger number. We should be attending to that. ;)
simon abingdon wrote: “I dismiss the possibility of intelligent life elsewhere in the universe on the simple grounds of improbability. There are just not enough stars to combat the formidable odds against … if we find that we can identify more than 8 independent 1/1000 conditions needed for the evolution of intelligent (technical) life …”
In short, you are dismissing the possibility of intelligent life elsewhere in the universe on the grounds of “formidable odds” that you just made up.
You claim that “Discovery of fossil fuels” (#7 in your list) is a requisite for the evolution of intelligent life? Are you kidding?
What you’ve got here is more like a list of requirements for the existence of a Duplicate Earth out of a Star Trek episode where the extraterrestrials making First Contact with humans all speak perfect English, rather than requirements for the evolution of intelligent life.
Frankly, I’m not sure we humans would even recognize extraterrestrial intelligence if we encountered it, given that we seem to have difficulty even acknowledging (let alone understanding) the intelligence of the other species with whom we share this planet.
Simon, in their famously pessimistic book Rare Earth: Why Complex Life Is Uncommon in the Universe Ward and Brownlee give their meaning of “uncommon” away in two places. Right at the beginning they say that the book will disappoint anyone who believes in a Star Trek universe with alien space ships everywhere you roam. Then at page 250 or so, when explaining why they think SETI won’t succeed, they say that there are probably several civilizations with radio telescopes in our galaxy, but the galaxy is so big that we are quite unlikely to ever detect them, or they us.
Wikipedia mentions 170 billion galaxies in the observable galaxies in the observable universe. For every planet with advance life, there must be many with some sort of microbial life. You had better check the Jovian moons again.
Perhaps the question is, “Which is easier to create from nothing, a universe (which Stephen Hawkins says is mathematically possible), or an all-powerful deity?”
As to how rare life is, I think we need a bigger sample. I visualize prions when I think of the beginning of life. Not alive, but they duplicate.
On topic, I think we had a discussion earlier where it was revealed that much of the mixing and heat exchange occurs on human time scales. Am I remembering that wrong?
Simon, the criteria you apply are not essential. Kepler has identified thousands of planets with stable orbits, and some within the range to support liquid water. It is not clear that a moon is essential, and while it is not clear that a giant guardian planet is essential (it may even be harmful to chances since it led to bombardment by comets and asteroids early in Earth’s history), large planets do not seem to be rare.
As to the rest of your criteria, they are nothing more than anthropocentrism–there is absolutely no reason why other planets should have a history of life similar to that of Earth.
As to your formulation of the problem, it is fallacious. I can prove by a similar argument that I don’t exist or that you don’t exist or that pretty much whatever proposition you choose to falsify is impossible. One problem is that you are assuming the probabilities are independent–many of them are correlated. Another is that your estimates of the probabilities are all rectally extracted–and they are about what you’d expect given that origin.
To lessen off-topic subthreads, move this comment to Unforced Variations, May 2013.
> much of the mixing and heat exchange occurs on human time scales.
Scholar, glancing, finds lots of papers with a variety of numbers. Fortunately Some persistent new chemicals are useful tracers of the mixing over the decades-to-centuries spans.
Simon, #130.
You might reflect that Mr. Benson’s comment was as yet unmoderated as I wrote…
But I still disagree with you, however disagreeable a tone you may choose to take: the ‘odds’ of abiogenesis really can’t be estimated reliably, the odds of potential alternate theories still less. Therefore, conclusions one may choose to draw really aren’t meaningful.
And worse, we’re a priori–a much *too* informative prior, perhaps one could say. That we are here can’t prove that we aren’t highly improbable.
#140 Ray Ladbury
Ray, you say “As to your formulation of the problem, it is fallacious… your estimates of the probabilities are all rectally extracted”. Maybe so, but you yourself can’t even produce the merest scintilla of real evidence that the universe actually is “teeming with life” let alone harbouring intelligent extraterrestrials.
You and your fellow-travellers seem to think that despite their overweening hubris SETI and the astrobiologists (don’t make me laugh) are going to come up trumps any day now.
Dream on.
[Response: Even a discussion about life in the universe has to be politicised? ‘Fellow-travellers’? Really? This is both stupid and off-topic even in an open thread. Enough thanks. – gavin]
#144 [Response gavin] You’re too touchy. It should have been obvious that I was referring to contributors who shared Ray’s view of the likelihood of extraterrestrial life. I have no interest in Ray’s political views nor could they possibly be any of my business.
Simon, Why not move to the new open thread?
If more of the heat from global warming is going into the ocean, does that reduce the amount of surface warming (both transiently and long-term) that we should expect from doubling CO2?
[Response: It reduces the transient response (or more accurately, it slows it), but it doesn’t affect the final destination which is dominated by atmospheric and land surface responses. – gavin]
I find it curious that nobody references the changes in sea surface height in the Navy models of the Barents and Newfoundland seas over the last year . It seems to me that a meter change in sea height would have provoked some comment. The changes in sea height strike me as evidence of ongoing changes in circulation.
See http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticsshnowcast.gif and
http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticssh_nowcast_anim365d.gif
“… Arctic Ocean sea-level rise is an important indicator of the rapid environmental and ecological changes in the Arctic region, but it is not well observed ….” (six slides with some info and sources, from an “Ocean Surface Topography Science Team Meeting” September 2012 )
http://www.aviso.oceanobs.com/fileadmin/documents/OSTST/2012/oral/01_thursday_27/02_regional_and_global_calval_I/06_CV1_Shum2.pdf
Obviously climate models have been way too conservative and are far off the actual warming trend. Conclusively they are wrong as they are enable to foresee the collapse of summer arctic ice. This will have probably significant consequences as positive feedback or may be climate switch in the coming years.
Are there any serious modeling of the effect of arctic ice loss on thermohaline temperature, methane degasing and run away effect on temperature ?
Thanks for answering.