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Sunday, February 21, 2016

Dyson vs 8 Aryan MIT scholars and Lindzen's comments on the exchange

Saturday, December 26, 2015

The unbearably low standards in "basics of science" at MIT


The Boston Globe recently published an exchange between legendary physicist Freeman Dyson and eight of his opponents who are employed by MIT, including a quark expert and a string theorist:

The second, anti-Dyson text was written by the hurricane opportunist Kerry Emanuel and by Robert Jaffe, a veteran of quark theory, and it was signed by 6 more MIT employees. In total, 3 of the people are physicists; the list includes string theorist Wati Taylor.

It is very obvious that to pretend that they have debunked Dyson, they felt that they have needed to collect a larger number of "authorities". The logic based on the "ad hominem fallacy" makes the anti-Dyson reply totally analogous to the 1931 pseudoscientific rant against relativity that was named A Hundred Authors Against Einstein. These 2nd class authors wanted to return physics to the 16th or 17th century and Einstein replied in a simple way: "If relativity were wrong, one author would have been enough to show it."

Richard Lindzen (who happens to be one man) wrote an insightful and amusing third-person analysis of the exchange between Dyson and 8 MIT employees at Anthony Watts' well-known website:
Lindzen: A recent exchange in the Boston Globe clearly illustrated the sophistic nature of the defense of global warming alarm
Dyson and Lindzen are climate skeptics which doesn't mean that they uncritically repeat the words of each other.

On the contrary, most climate skeptics typically avoid the group think and that's true even "inside" the climate skeptic community. Lindzen's report shows an example of that characteristic independence. When Dyson and Lindzen disagree with each other, I mostly agree with Dick although I am not as pure a Lindzen as he is. ;-)

The most obvious point of a disagreement between Dyson and Lindzen is that Dyson says that the IPCC says that the science (of climate change) is settled; and it's the IPCC that is the Urquell of the efforts to reduce CO2 emissions. Lindzen says that the IPCC says that the science is work in progress (because the IPCC members' salaries are derived from the assumption that they keep on doing research so it can't be settled yet); and the IPCC avoids policy recommendations and dramatic interpretations which are only later added by activists and politicians. The IPCC only cooperates passively by not objecting.

I think that Lindzen's description is the more accurate one. The actual IPCC reports are written by people hired as scientists so they simply can't pretend that the science is over because that would make their daily job redundant. And yes, I do think that the actual IPCC reports are mostly filled with regular science, sometimes boring science and often legitimate science, and the dramatic oversimplified alarmist interpretations are added as a bonus by "leaders" and especially "outsiders".

Well, it's more complicated than that. The bulk of the IPCC reports are "conventional, often boring science" but that bulk isn't too important. The summaries are way more important and they're way more policy-oriented, hysterical, and oversimplified. And even the summaries are considered too long and complicated by too many people, including most of the alarmist politicians, so these effectively work with even more concise (and oversimplified, distorted, and dramatic) summaries of the summaries. And with summaries of summaries of summaries – which are equivalent to idiotic hysterical slogans that have almost nothing to do with the science.

Moreover, one shouldn't forget that the IPCC has three working groups – and only the first one (focusing on the physical mechanisms of the "problem") fully agrees with Dick's description. The other two IPCC working groups are increasingly social and political in character. For these other two working groups, Dyson's description is increasingly close to the truth.

There's one additional point where I totally agree with Dick. The main problem with the alarmist interpretation of the climate science isn't the magnitude of the climate sensitivity (although I find Lindzen's own below-1-Celsius-degree values to be more likely than those above 2 degrees); the main problem is that many people love to deduce far-reaching, sensational consequences out of the effect of CO2 even though the effect is almost certainly very minor even according to the IPCC reports themselves.

The "refined" statement about the important role of the humans in global warming is formulated by the IPCC Working Group 1 as:
The IPCC report presents strong evidence that more than half of the climate change seen in recent decades is human-driven.
And many people tend to use the agreement or disagreement with the statement above as a criterion to distinguish alarmists from skeptics. Well, like Lindzen, I consider myself a full-fledged denier but I am totally open-minded about the quote above. In my opinion, people just don't think carefully and rationally about the sentence above.

Imagine that the sentence speaks about the recent 60 years or so. In those 60 years, the global mean temperature could have increased by something like 0.6 °C – that's the end-minus-beginning difference of a linear function interpolating the noisy temperature graphs via linear regression. With these values, the IPCC WG1 "iconic" statement says
The IPCC believes that the mankind has contributed at least 0.3 °C of warming of the globe in the recent 60 years.
Is it true? I honestly don't know. My estimate is that the right figure is probably below 0.3 °C but the degree of my "certainty" about that claim is very limited, not strongly exceeding 50 percent. In other words, as far as I can say, the sentence may be either true or false. But if the sentence is true, does it mean that there is a reason for panic or reductions of CO2 emissions justified by the fear of climate change? The sentence just says that since 1955 when most of the TRF readers weren't born yet, the temperatures have increased by three tenths of a Celsius degree because of CO2 (only the partial CO2 contribution is counted in the temperature figure). This is such a small temperature change that you just can't feel it on your skin even when it occurs abruptly. It's much harder to "feel it" if you have to wait for 60 years; and if you need to deduce the value from careful measurements and statistical analyses (averaging over the places, days+nights, and seasons) of the temperatures on the whole globe.

Many people, including those who consider themselves skeptics, just become totally irrational when they're expected to think about these matters. The point is that this change of the temperature by 0.3 °C – and IPCC doesn't really claim to be too convinced about any "faster" warming trend – is indistinguishable from zero for all practical purposes. It's a temperature change smaller than the effect of one large volcano eruption; one El Niño episode.

Or take our very mild winter. We Central Europeans had a nice spring day today; the temperature has reached 11 °C in the afternoon. People living in the Eastern part of the U.S. can say something similar; the western portions of the U.S. enjoy a rather old-fashioned winter, however.

But now, it's natural for many people to think about the mild winter in the context of the man-made climate change. By the constant repetition, people's intuitive thinking – including mine – has been contaminated and we just can't avoid thinking about "global warming" whenever the weather is mild or hot. The problem with that knee-jerk reaction is that the iconic IPCC statement is just "somewhat convinced" that in the last 60 years, the CO2 emissions have contributed at least 0.3 °C. It means that if there had been no CO2 emissions, the today's high temperature in Pilsen would be – according to the IPCC statement – not 11 °C but at most 10.7 °C. Look at these two numbers carefully.

The qualitative point is that according to the scientifically justifiable evidence, the CO2 emissions have had such a small effect on the temperature that if there had been no emissions since the World War II at all, it would make virtually no impact on the fact that the 2015 Christmas had no chance to be a white Christmas in Pilsen! Even if the CO2 sensitivity were 3 times higher than that, we would have over 8 °C in the afternoon and the snow (if any) would have no chance to survive.

Dick's point, one that I totally agree with, is that even according to the IPCC Working Group 1, the CO2 effect is so incredibly weak that it just wouldn't make any detectable difference for the qualitative things that matter – like a sunny Czech Christmas in 2015. We have had winds mostly from the South for a week or two and that makes a difference, especially during a very strong El Niño episode.

But I have spent too much time with the "flavors of skeptics". In various contexts, I feel closest to Richard Lindzen or Bob Carter or other great men. Needless to say, most of the actual confrontation and disagreement isn't in between pairs of skeptics; it's between skeptics and the alarmists.

Lindzen says that the reply by the 8 MIT physicists is "sophistic". I think that the shallow reply by Wati Taylor and his 7 comrades could be written on an MIT place mat – what you, an MIT freshman, should tell your family and uncle about the climate change during the Christmas conversations. I am really baffled that e.g. Wati Taylor isn't ashamed of adding his signature under similarly incredibly misleading and sometimes downright false slogans. This is just so pathetic, Wati. And something is extremely sick about the MIT physics department when you fail to become an instant anti-science pariah with this kind of junk.

For example, take the simple and absolutely uncontroversial statement at the end of Dyson's article that "the main effect of CO2 is to make the planet greener". Taylor and 7 comrades obviously find this statement to be an inconvenient truth so they try to hide it in a bizarre demagogic fog such as
The proposal that the “main effect of carbon dioxide is to make the planet greener” overlooks the constraints imposed by the availability of other nutrients and the disruption of the biosphere caused by the direct effects of climate change.
Wati, can't you see how incredibly demagogic, dumb, and misleading such a comment about "overlooked constraints" is? Dyson has said just something that every fifth grader should or must know before she becomes a sixth grader. Plants eat CO2. In the process of photosynthesis, with the help of the solar energy coming to the leaves, the oxygen and carbon atoms are separated while CO2 is removed from the atmosphere, the chemical energy of the atoms increases by the separation (it's just like when you are recharging a battery; the carbon and oxygen atoms are ready to be usefully "burned" by animals or power plants), the carbon atoms are incorporated to the plants' biomass, and the oxygen is returned to the air.

It's obvious that because CO2 is the main material from which the "solid" part of the plants is ultimately built (no, the big tree hasn't removed the same amount of "solid" material from the soil, it took the "solid" material mostly from the air!), a higher concentration of CO2 makes the life of the plants easier. Some plant species are very sensitive about the shortage of CO2; other species are less sensitive. An "average" plant's growth increases by 0.5% whenever you increase the concentration of CO2 in the air by 1%.

Microscopically, the plants like a higher CO2 concentration because their pores may be smaller or less numerous and it's still enough to get the required amount of CO2 from the air (when and because the CO2 levels are higher). And when the pores are smaller or less numerous, the leaves lose less water vapor – which evaporates through the pores. In this way, the plants become more water-efficient and less sensitive to shortage of water and that's the ultimate reason why they flourish in high-CO2 environments.

Hundreds of experiments have been performed and hundreds of papers have been written about these most direct effects of CO2. There exist greenhouses where the higher CO2 is actively exploited. And I think that there may exist schoolkids who actually know much more than the basic wisdom I have sketched above. Now, Wati, are you smarter than a fifth grader? Do you want to avoid the discussion of all the details by denying the very basic point by Dyson that the increased plant growth is the most direct effect of higher CO2 concentrations? Can you appreciate how incredibly stupid this denial is? Are there any people left at MIT who are smarter than a fifth grader and who will point out to you that you may be a string theorist but when it comes to basics of biology, you are just a complete, 100% imbecile?

And it's not just your straight denial of photosynthesis as the main life process that depends on CO2 levels in the air. There are tons of other, incredibly stupid slogans in your rant – some of them are written down explicitly and some of them are written down implicitly. In the sentence in which you denied photosynthesis (and claimed that Dyson has "overlooked" something – be sure that he hasn't overlooked anything when his point was just to make the spectacularly obviously correct claim about photosynthesis), you also wrote about "the disruption of biosphere caused by the direct effects of the climate change".

What? Have you lost your mind?

There is absolutely nothing "direct" about the hypothetical effects of CO2 on the plant's life through meteorological phenomena. According to the IPCC, the elevated CO2 levels only increase the global mean temperature by more than 0.3 °C in 60 years with a probability just barely exceeding 50%, according to their estimate. It is spectacularly clear that a change of the temperature by 0.3 °C in either direction has a negligible effect on a plant relatively to the change of the amount of the available "food" by 40%.

Just think about it from a human perspective. Imagine that you solve similar problems as a plant. You ate something last week. Next week, you may either have the same amount of food and the temperatures higher or lower than 0.3 °C; or you may enjoy the same temperature but the amount of available food (I mean sugars, fats, and proteins) you may eat will drop by 30 or 40 percent. Which change is more important or more directly consequential for your well-being, (a) a temperature change by 0.3 °C or (b) the decrease of food supply by 30 or 40 percent? Do you realize that by your unhinged anti-Dyson rant, you have picked the answer (a)? Are you serious?

Now, there are other nutrients beyond sugars, fats, and proteins that humans need. Does it change anything about the fact that the change of the amount of sugars, fats, and proteins available to you by 30-40 percent is the most consequential change among those we have considered? If you realize that the answer is a resounding "no, it changes nothing", why the hell do you mention other nutrients at all? You're just trying to make people look at some distractions instead of the key thing and you must know that, mustn't you? Or are you really a complete idiot?

And be sure about it, the greenhouse effect of CO2 causes a pretty much uniform warming across the Earth's surface. It's because by the diffusion, the CO2 concentration gets quickly homogeneous; and the greenhouse effect controls the absorption of Earth's thermal radiation which is always comparable at relatively nearby places of the Earth – because the thermal radiation is proportional to the fourth power of the absolute temperature.

The greenhouse effect doesn't change much about pressure and temperature differences, vortices, storms, precipitation etc. If there is any influence of the mostly uniform change on the more visible weather phenomena, it's a spectacularly small 2nd or 3rd order effect. Even the 1st order effect, a change of the temperature by "at least 0.3 °C", was almost certainly negligible. Now try to calculate the non-uniformities of the greenhouse effect and its impact on pressure differences or the ability to increase torrential rains or hurricanes that can influence a plant. Can these effects be stronger than a 40% increase of the main "food"? Is your brain enough to see that those influences of CO2 through the weather patterns are absolutely negligible relatively to the change of the food by 40%? If you're not, I won't really believe that it is you who wrote the papers about string theory. In that case, you are dumb as a doorknob and you must have someone else who was writing them and you are declared as the author because author lists with unhinged climate alarmists in them look more politically correct.

And the problems with the rant that you signed go on and on and on. The rant is very short but literally every sentence contains several explosive stupidities and easy-to-spot demagogy. You are basically working hard to deny all basic facts about Earth and life sciences, along with tons of basics of physics – the importance of photosynthesis, the importance of the Sun for the climate, the fact that ice ages bring a much more substantial cooling than the warming caused by CO2, the fact that some known episodes of climate change in the past have occurred within decades so it's simply not true that it always takes thousands of years. You also try to deny the self-evident point that every individual human and animal is capable of instantaneous adaptation to the temperature change by a degree or two. Your pretty much explicit claim that one needs thousands of years to adapt to 1 °C of warming is absolutely idiotic so that the intelligent third graders will see it, too.

Moreover, your vague suggestion that the humans and other species are significantly evolving in the time frame of thousands of years (during the glaciation cycles) – when the temperature changes by several degrees – is mostly rubbish, too. Real revolution occurs much more slowly than the glaciation cycles. Glaciation cycles take tens or at most hundreds of years; evolution normally needs millions of years. No significant biological evolution has been taking place in between the phases of the glaciation cycles; at most, one race of subspecies etc. became more widespread than others.

Even though the anti-Dyson rant is so short, this essay could continue for hours.

It just drives me up the wall how incredibly lousy intellectual standards are routinely tolerated e.g. in the MIT physics department when some politically correct "causes" are being defended. You know, communism has been crippling our society and the nation's morality in many ways but I honestly don't remember a single example of Czechoslovak communists' distorting influence of the natural sciences that could be at least remotely compared to the climate alarmists' distortions of photosynthesis, ice ages, solar output, sensitivity of plants on the temperature, CO2, nutrients, water, whatever. The only good enough analogy I can think of is the ban of genetics in the Soviet Union. I am sure that you love to suggest that you're better than the Lysenkoists but you are not.

The authors of the anti-Dyson rant in the Boston Globe should be deeply ashamed and I encourage their students to spit into the authors' faces and to demand a significant discount if they pay a tuition.

Pliocene


From Wikipedia, the free encyclopedia

System/
Period
Series/
Epoch
Stage/
Age
Age (Ma)
Quaternary Pleistocene Gelasian younger
Neogene Pliocene Piacenzian 3.600–2.58
Zanclean 5.333–3.600
Miocene Messinian 7.246–5.333
Tortonian 11.62–7.246
Serravallian 13.82–11.62
Langhian 15.97–13.82
Burdigalian 20.44–15.97
Aquitanian 23.03–20.44
Paleogene Oligocene Chattian older
Subdivision of the Neogene Period
according to the IUGS, [v2014/02].
The Pliocene (/ˈpləˌsn/;[1][2] also Pleiocene) Epoch (symbol PO[3]) is the epoch in the geologic timescale that extends from 5.333 million to 2.58[4] million years BP. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch. Prior to the 2009 revision of the geologic time scale, which placed the four most recent major glaciations entirely within the Pleistocene, the Pliocene also included the Gelasian stage, which lasted from 2.588 to 1.806 million years ago, and is now included in the Pleistocene.[5]
As with other older geologic periods, the geological strata that define the start and end are well identified but the exact dates of the start and end of the epoch are slightly uncertain. The boundaries defining the Pliocene are not set at an easily identified worldwide event but rather at regional boundaries between the warmer Miocene and the relatively cooler Pliocene. The upper boundary was set at the start of the Pleistocene glaciations.

Etymology

The Pliocene was named by Sir Charles Lyell. The name comes from the Greek words πλεῖον (pleion, "more") and καινός (kainos, "new")[6] and means roughly "continuation of the recent", referring to the essentially modern marine mollusc faunas. H.W. Fowler called the term (along with other examples such as pleistocene and miocene) a "regrettable barbarism" and an indication that even "a good classical scholar" such as Lyell should have requested a philologist's help when coining words.[7]

Subdivisions

In the official timescale of the ICS, the Pliocene is subdivided into two stages. From youngest to oldest they are:
The Piacenzian is sometimes referred to as the Late Pliocene, whereas the Zanclean is referred to as the Early Pliocene.

In the system of
In the Paratethys area (central Europe and parts of western Asia) the Pliocene contains the Dacian (roughly equal to the Zanclean) and Romanian (roughly equal to the Piacenzian and Gelasian together) stages. As usual in stratigraphy, there are many other regional and local subdivisions in use.
In Britain the Pliocene is divided into the following stages (old to young): Gedgravian, Waltonian, Pre-Ludhamian, Ludhamian, Thurnian, Bramertonian or Antian, Pre-Pastonian or Baventian, Pastonian and Beestonian. In the Netherlands the Pliocene is divided into these stages (old to young): Brunssumian C, Reuverian A, Reuverian B, Reuverian C, Praetiglian, Tiglian A, Tiglian B, Tiglian C1-4b, Tiglian C4c, Tiglian C5, Tiglian C6 and Eburonian. The exact correlations between these local stages and the ICS stages is still a matter of detail.[8]

Climate

Mid-Pliocene reconstructed annual sea surface temperature anomaly

The global average temperature in the mid-Pliocene (3.3–3 mya) was 2–3 °C higher than today,[9] global sea level 25 m higher[10] and the Northern hemisphere ice sheet was ephemeral before the onset of extensive glaciation over Greenland that occurred in the late Pliocene around 3 Ma.[11] The formation of an Arctic ice cap is signaled by an abrupt shift in oxygen isotope ratios and ice-rafted cobbles in the North Atlantic and North Pacific ocean beds.[12] Mid-latitude glaciation was probably underway before the end of the epoch. The global cooling that occurred during the Pliocene may have spurred on the disappearance of forests and the spread of grasslands and savannas.[13]

Paleogeography


Examples of migrant species in the Americas after the formation of the Isthmus of Panama. Olive green silhouettes denote North American species with South American ancestors; blue silhouettes denote South American species of North American origin.

Continents continued to drift, moving from positions possibly as far as 250 km from their present locations to positions only 70 km from their current locations. South America became linked to North America through the Isthmus of Panama during the Pliocene, making possible the Great American Interchange and bringing a nearly complete end to South America's distinctive large marsupial predator and native ungulate faunas. The formation of the Isthmus had major consequences on global temperatures, since warm equatorial ocean currents were cut off and an Atlantic cooling cycle began, with cold Arctic and Antarctic waters dropping temperatures in the now-isolated Atlantic Ocean.

Africa's collision with Europe formed the Mediterranean Sea, cutting off the remnants of the Tethys Ocean. The border between the Miocene and the Pliocene is also the time of the Messinian salinity crisis.

Sea level changes exposed the land-bridge between Alaska and Asia.

Pliocene marine rocks are well exposed in the Mediterranean, India, and China. Elsewhere, they are exposed largely near shores.

Flora

The change to a cooler, dry, seasonal climate had considerable impacts on Pliocene vegetation, reducing tropical species worldwide. Deciduous forests proliferated, coniferous forests and tundra covered much of the north, and grasslands spread on all continents (except Antarctica). Tropical forests were limited to a tight band around the equator, and in addition to dry savannahs, deserts appeared in Asia and Africa.

Fauna

Both marine and continental faunas were essentially modern, although continental faunas were a bit more primitive than today. The first recognizable hominins, the australopithecines, appeared in the Pliocene.

The land mass collisions meant great migration and mixing of previously isolated species, such as in the Great American Interchange. Herbivores got bigger, as did specialized predators.

Mammals

In North America, rodents, large mastodons and gomphotheres, and opossums continued successfully, while hoofed animals (ungulates) declined, with camel, deer and horse all seeing populations recede. Rhinos, three toed horses (Nannippus), oreodonts, protoceratids, and chalicotheres went extinct. Borophagine dogs and Agriotherium went extinct, but other carnivores including the weasel family diversified, and dogs and fast-running hunting bears did well. Ground sloths, huge glyptodonts, and armadillos came north with the formation of the Isthmus of Panama.
In Eurasia rodents did well, while primate distribution declined. Elephants, gomphotheres and stegodonts were successful in Asia, and hyraxes migrated north from Africa. Horse diversity declined, while tapirs and rhinos did fairly well. Cows and antelopes were successful, and some camel species crossed into Asia from North America. Hyenas and early saber-toothed cats appeared, joining other predators including dogs, bears and weasels.

Human evolution during the Pliocene

Pliocene mammals of North America

Africa was dominated by hoofed animals, and primates continued their evolution, with australopithecines (some of the first hominins) appearing in the late Pliocene. Rodents were successful, and elephant populations increased. Cows and antelopes continued diversification and overtaking pigs in numbers of species. Early giraffes appeared, and camels migrated via Asia from North America. Horses and modern rhinos came onto the scene. Bears, dogs and weasels (originally from North America) joined cats, hyenas and civets as the African predators, forcing hyenas to adapt as specialized scavengers.

South America was invaded by North American species for the first time since the Cretaceous, with North American rodents and primates mixing with southern forms. Litopterns and the notoungulates, South American natives, were mostly wiped out, except for the macrauchenids and toxodonts, which managed to survive. Small weasel-like carnivorous mustelids, coatis and short faced bears migrated from the north. Grazing glyptodonts, browsing giant ground sloths and smaller caviomorph rodents, pampatheres, and armadillos did the opposite, migrating to the north and thriving there.

The marsupials remained the dominant Australian mammals, with herbivore forms including wombats and kangaroos, and the huge diprotodon. Carnivorous marsupials continued hunting in the Pliocene, including dasyurids, the dog-like thylacine and cat-like Thylacoleo. The first rodents arrived in Australia. The modern platypus, a monotreme, appeared.

Birds


Titanis

The predatory South American phorusrhacids were rare in this time; among the last was Titanis, a large phorusrhacid that migrated to North America and rivaled mammals as top predator. Other birds probably evolved at this time, some modern, some now extinct.

Reptiles and amphibians

Alligators and crocodiles died out in Europe as the climate cooled. Venomous snake genera continued to increase as more rodents and birds evolved. Rattlesnakes first appeared in the Pliocene. The modern species Alligator mississippiensis, having evolved in the Miocene, continued into the Pliocene, except with a more northern range; specimens have been found in very late Miocene deposits of Tennessee. Giant tortoises still thrived in North America, with genera like Hesperotestudo. Madtsoid snakes were still present in Australia. The amphibian order Allocaudata went extinct.

Oceans

Oceans continued to be relatively warm during the Pliocene, though they continued cooling. The Arctic ice cap formed, drying the climate and increasing cool shallow currents in the North Atlantic. Deep cold currents flowed from the Antarctic.

The formation of the Isthmus of Panama about 3.5 million years ago cut off the final remnant of what was once essentially a circum-equatorial current that had existed since the Cretaceous and the early Cenozoic. This may have contributed to further cooling of the oceans worldwide.

The Pliocene seas were alive with sea cows, seals and sea lions.

Supernovae

In 2002, Narciso Benítez et al. calculated that roughly 2 million years ago, around the end of the Pliocene epoch, a group of bright O and B stars called the Scorpius-Centaurus OB association passed within 130 light-years of Earth and that one or more supernova explosions gave rise to a feature known as the Local Bubble.[14] Such a close explosion could have damaged the Earth's ozone layer and caused the extinction of some ocean life (at its peak, a supernova of this size could have the same absolute magnitude as an entire galaxy of 200 billion stars).[15][16]

Thursday, February 11, 2016

Molecular Radiation and Collisional Lifetime

Posted by Jeff Id on August 17, 2010

DeWitt Payne has kindly completed a nice post explaining how re-absorption of photons emitted by CO2 or other molecules doesn’t appreciably affect the ratio of energy transfer in the atmosphere due to IR emission vs absorption (or molecular collision).  It’s another commonly debated topic often improperly cited by critics of the warming effects of CO2. When it’s not expressed correctly, it’s a clue that the individual is less knowledgeable on the science than they may appear.  I’m sure everyone will agree that whatever your position on global warming, the basics are critical to making a sound, science based argument.

I’ve done a bit of reformatting for clarity–Jeff
——————–
Have you ever seen or heard the statement that CO2 can’t emit radiation in the atmosphere because the decay time for spontaneous emission is long compared to the collisional life?  Guess what, that’s completely wrong.  A molecule or atom in an excited state has no knowledge of its age.  The probability of decay is the same whether the excited state has existed for centuries or picoseconds.  The rate of decay of a collection of things in an excited state depends only on the number of things in the excited state, Ni, and the decay constant Kd. The decay constant has units of reciprocal seconds (s-1).

So
dNi/dt=-Kd*Ni
and
Ni(t)=Ni(0)exp(-t*Kd)

The decay constant is often expressed as the half-life or the amount of time it takes for half the initial number of things to decay.  The half-life is equal to ln(2)/Kd.

The difference between radioactive decay and molecular decay in an atmosphere is that for molecular decay, the number of molecules in the excited state is constant at constant temperature and pressure.  CO2 molecules are continually being raised to the excited state and the excited states are lowered back to the ground state by inelastic collisions with other molecules.  In inelastic collisions, kinetic energy is converted to vibrational energy and back.  Most molecular collisions are elastic and total kinetic energy is preserved.  Only about 1 in 10,000 collisions is inelastic at Earth surface temperature and pressure.  Since the mean time between collisions is about 1 ns under those conditions, that means the expected lifetime of a CO2 molecule excited to the 15 micrometer vibrational excited state is on the order of 1-10 microseconds.  This also means that only about 1 in 10,000 excited molecules decays by emission of radiation rather than collision.  For a system to be in local thermal equilibrium it is necessary for this ratio to be very small.

The decay constant for a molecular line is the Einstein A21 coefficient.  The value of A21 for any ghg molecular transition can be found in the HITRAN database.  The database can be searched using the extract data tab in the line browser feature of SpectralCalc ( http://www.spectralcalc.com/spectral_browser/db_data.php ).  For the most intense CO2 line at 667.6612 cm-1, the A21 coefficient is 1.542 s-1 or a half life of 0.45 s.

The number of molecules in the excited state depends only on the energy of the excited state and the temperature through the Maxwell-Boltzmann distribution.   For the 667.6612 cm-1 CO2 line at 296 K:
Ni/N = exp(-Ei/kT) = exp (-hν/kT) =0.039

What does that actually mean in terms of radiance?

No significant absorption model:

Let’s take a very thin layer of gas so that self absorption can be neglected.  If we use surface atmospheric conditions with a CO2 volume mixing ratio (VMR) of 0.00038, the transmittance at the line peak according to SpectralCalc is 0.992 for a layer 2 mm thick.  The absorptance is 1-0.992 or 0.008.  For a surface area of 1 m2, that’s a volume of 0.002 m3.  At STP (1013 mbar and 273.2 K) there are 0.0224 m3/mole and 6.022E23 molecules/mole.  Correcting for the temperature difference between 296 and 273.2 and the VMR, there are (6.022E23*0.002*0.00038*273.2)/(0.0224*296)=1.89E19 CO2 molecules /m2 and 1.89E19*0.039=7.35E17 molecules in the excited state.  That gives 1.542*7.35E17=7.13E18 photons/sec.  The photon energy is hν=1.33E-20 and a radiance (ignoring layer thickness) of 7.13E18*1.33E-20/4π= 1.20E-03 W m-2 sr-1.

Bulk atmosphere model:

Now let’s take the same layer of gas and calculate the radiance using the Planck equation.  For an emissivity of 0.008, a frequency in cm-1 and radiance in W m-2 sr-1:
I(υ,T)= ε*(1.191427E-08*υ3)/(exp(1.438775*ν/T)-1)= 1.15E-03 W m-2 sr-1.
1.20E-03 W m-2 sr-1 approximately equates to 1.15E-03 W m-2 sr-1.
It’s distinctly possible I’ve made multiple errors here, but if I did, they appear to cancel out.

Tuesday, February 9, 2016

Holocene


From Wikipedia, the free encyclopedia

Subdivisions of the Quaternary System
System/
Period
Series/
Epoch
Stage/
Age
Age (Ma)
Quaternary Holocene 0.0117–0
Pleistocene Tarantian 0.126–0.0117
Ionian 0.781–0.126
Calabrian 1.80–0.781
Gelasian 2.58–1.80
Neogene Pliocene Piacenzian older
In Europe and North America, the Holocene is subdivided into Preboreal, Boreal, Atlantic, Subboreal, and Subatlantic stages of the Blytt–Sernander time scale. There are many regional subdivisions for the Upper or Late Pleistocene; usually these represent locally recognized cold (glacial) and warm (interglacial) periods. The last glacial period ends with the cold Younger Dryas substage.

The Holocene /ˈhɒləˌsn, ˈh-/[1][2] is the geological epoch that began after the Pleistocene[3] at approximately 11,700 years before the year 2000AD [4]:3 and continues to the present. The term "Recent" (usually capitalised) has often been used as an exact synonym of "Holocene", although this usage is discouraged in 21st-century work.[5] The Holocene is part of the Quaternary period. Its name comes from the Greek words ὅλος (holos, whole or entire) and καινός (kainos, new), meaning "entirely recent".[6] It has been identified with the current warm period, known as MIS 1, and can be considered an interglacial in the current ice age based on that evidence.

The Holocene also encompasses the growth and impacts of the human species worldwide, including all its written history, development of major civilizations, and overall significant transition toward urban living in the present. Human impacts on modern-era Earth and its ecosystems may be considered of global significance for future evolution of living species, including approximately synchronous lithospheric evidence, or more recently atmospheric evidence of human impacts. Given these, a new term, Anthropocene, is specifically proposed and used informally only for the very latest part of modern history and of significant human impact since the epoch of the Neolithic Revolution (around 12,000 years BP).

Overview

It is accepted by the International Commission on Stratigraphy that the Holocene started approximately 11,701 years BP (before present).[4] The epoch follows the Pleistocene and the last glacial period (local names for the last glacial period include the Wisconsinan in North America,[7] the Weichselian in Europe,[8] the Devensian in the United Kingdom,[9] the Llanquihue in Chile[10] and the Otiran in New Zealand[11]). The Holocene can be subdivided into five time intervals, or chronozones, based on climatic fluctuations:[12]
Note: "ka" means "thousand years" (non-calibrated C14 dates)
The Blytt–Sernander classification of climatic periods defined, initially, by plant remains in peat mosses, is now being explored currently by geologists working in different regions studying sea levels, peat bogs and ice core samples by a variety of methods, with a view toward further verifying and refining the Blytt–Sernander sequence. They find a general correspondence across Eurasia and North America, though the method was once thought to be of no interest. The scheme was defined for Northern Europe, but the climate changes were claimed to occur more widely. The periods of the scheme include a few of the final pre-Holocene oscillations of the last glacial period and then classify climates of more recent prehistory.[citation needed]

Paleontologists have defined no faunal stages for the Holocene. If subdivision is necessary, periods of human technological development, such as the Mesolithic, Neolithic, and Bronze Age, are usually used. However, the time periods referenced by these terms vary with the emergence of those technologies in different parts of the world.[citation needed]

Climatically, the Holocene may be divided evenly into the Hypsithermal and Neoglacial periods; the boundary coincides with the start of the Bronze Age in European civilization. According to some scholars, a third division, the Anthropocene, began in the 18th century.[13]

Geology


Holocene cinder cone volcano on State Highway 18 near Veyo, Utah

Continental motions due to plate tectonics are less than a kilometre over a span of only 10,000 years. However, ice melt caused world sea levels to rise about 35 m (115 ft) in the early part of the Holocene. In addition, many areas above about 40 degrees north latitude had been depressed by the weight of the Pleistocene glaciers and rose as much as 180 m (590 ft) due to post-glacial rebound over the late Pleistocene and Holocene, and are still rising today.[14]

The sea level rise and temporary land depression allowed temporary marine incursions into areas that are now far from the sea. Holocene marine fossils are known from Vermont, Quebec, Ontario, Maine, New Hampshire, and Michigan. Other than higher-latitude temporary marine incursions associated with glacial depression, Holocene fossils are found primarily in lakebed, floodplain, and cave deposits. Holocene marine deposits along low-latitude coastlines are rare because the rise in sea levels during the period exceeds any likely tectonic uplift of non-glacial origin.[citation needed]

Post-glacial rebound in the Scandinavia region resulted in the formation of the Baltic Sea. The region continues to rise, still causing weak earthquakes across Northern Europe. The equivalent event in North America was the rebound of Hudson Bay, as it shrank from its larger, immediate post-glacial Tyrrell Sea phase, to near its present boundaries.[citation needed]

Climate


Temperature variations during the Holocene

Paleogeographic reconstruction of the North Sea approximately 9,000 years ago during the early Holocene and after the end of the last ice age.

Climate has been fairly stable over the Holocene. Ice core records show that before the Holocene there was global warming after the end of the last ice age and cooling periods, but climate changes became more regional at the start of the Younger Dryas. During the transition from the last glacial to the Holocene, the Huelmo–Mascardi Cold Reversal in the Southern Hemisphere began before the Younger Dryas, and the maximum warmth flowed south to north from 11,000 to 7,000 years ago. It appears that this was influenced by the residual glacial ice remaining in the Northern Hemisphere until the later date.[citation needed]

The hypsithermal was a period of warming in which the global climate became warmer. However, the warming was probably not uniform across the world. This period of warmth ended about 5,500 years ago with the descent into the Neoglacial. At that time, the climate was not unlike today's, but there was a slightly warmer period from the 10th–14th centuries known as the Medieval Warm Period. This was followed by the Little Ice Age, from the 13th or 14th century to the mid 19th century, which was a period of significant cooling, though not everywhere as severe as previous times during neoglaciation.[citation needed]

The Holocene warming is an interglacial period and there is no reason to believe that it represents a permanent end to the current ice age.[citation needed]

Compared to glacial conditions, habitable zones have expanded northwards, reaching their northernmost point during the hypsithermal. Greater moisture in the polar regions has caused the disappearance of steppe-tundra.[citation needed]

The temporal and spatial extent of Holocene climate change is an area of considerable uncertainty, with solar forcing recently proposed to be the origin of cycles identified in the North Atlantic region. Climate cyclicity through the Holocene (Bond events) has been observed in or near marine settings and is strongly controlled by glacial input to the North Atlantic.[15][16] Periodicities of ~2500, ~1500, and ~1000 years are generally observed in the North Atlantic.[17][18][19] At the same time spectral analyses of the continental record, which is remote from oceanic influence, reveal persistent periodicities of 1000 and 500 years that may correspond to solar activity variations during the Holocene epoch.[20] A 1500-year cycle corresponding to the North Atlantic oceanic circulation may have widespread global distribution in the Late Holocene.[20]

Ecological developments

Animal and plant life have not evolved much during the relatively short Holocene, but there have been major shifts in the distributions of plants and animals. A number of large animals including mammoths and mastodons, saber-toothed cats like Smilodon and Homotherium, and giant sloths disappeared in the late Pleistocene and early Holocene—especially in North America, where animals that survived elsewhere (including horses and camels) became extinct. This extinction of American megafauna has been explained as caused by the arrival of the ancestors of Amerindians; though most scientists assert that climatic change also contributed. In addition, a controversial bolide impact over North America has been hypothesized to have triggered the Younger Dryas.[21]

Throughout the world, ecosystems in cooler climates that were previously regional have been isolated in higher altitude ecological "islands".[citation needed]

The 8.2 ka event, an abrupt cold spell recorded as a negative excursion in the δ18O record lasting 400 years, is the most prominent climatic event occurring in the Holocene epoch, and may have marked a resurgence of ice cover. It is thought that this event was caused by the final drainage of Lake Agassiz, which had been confined by the glaciers, disrupting the thermohaline circulation of the Atlantic.[22]

Human developments

Bronze bead necklace, Muséum de Toulouse

The beginning of the Holocene corresponds with the beginning of the Mesolithic age in most of Europe; but in regions such as the Middle East and Anatolia with a very early neolithisation, Epipaleolithic is preferred in place of Mesolithic. Cultures in this period include: Hamburgian, Federmesser, and the Natufian culture, during which the oldest inhabited places still existing on Earth were first settled, such as Jericho in the Middle East,[23] as well as evolving archeological evidence of proto-religion at locations such as Göbekli Tepe, as long ago as the 9th millennium BCE.[24]

Both are followed by the aceramic Neolithic (Pre-Pottery Neolithic A and Pre-Pottery Neolithic B) and the pottery Neolithic. The Late Holocene brought advancements such as the bow and arrow and saw new methods of warfare in North America. Spear throwers and their large points were replaced by the bow and arrow with its small narrow points beginning in Oregon and Washington. Villages built on defensive bluffs indicate increased warfare, leading to food gathering in communal groups for protection rather than individual hunting.[25]

Inquiry-based learning

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