Miocene

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 Miocene (/ˈmaɪəˌsiːn/;^[1][2] symbol M_I^[3]) is the first geological epoch of the Neogene Period and extends from about 23.03 to 5.332 million years ago (Ma). The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words μείων (meiōn, “less”) and καινός (kainos, “new”)^[4] and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene Epoch and is followed by the Pliocene Epoch.

The earth went from the Oligocene through the Miocene and into the Pliocene as it cooled into a series of ice ages. The Miocene boundaries are not marked by a single distinct global event but consist rather of regional boundaries between the warmer Oligocene and the cooler Pliocene.

The apes arose and diversified during the Miocene, becoming widespread in the Old World. By the end of this epoch, the ancestors of humans had split away from the ancestors of the chimpanzees to follow their own evolutionary path. As in the Oligocene before it, grasslands continued to expand and forests to dwindle in extent. In the Miocene seas, kelp forests made their first appearance and soon became one of Earth's most productive ecosystems. ^[5] The plants and animals of the Miocene were fairly modern. Mammals and birds were well-established. Whales, seals, and kelp spread. The Miocene is of particular interest to geologists and palaeoclimatologists as major phases of the Himalayan orogeny had occurred during the Miocene affecting monsoonal patterns in Asia, which were interlinked with glaciations in the northern hemisphere.^[6]

Subdivisions

The Miocene faunal stages from youngest to oldest are typically named according to the International Commission on Stratigraphy:^[7]

Messinian	(7.246–5.332 Ma)
Tortonian	(11.608–7.246 Ma)
Serravallian	(13.65–11.608 Ma)
Langhian	(15.97–13.65 Ma)
Burdigalian	(20.43–15.97 Ma)
Aquitanian	(23.03–20.43 Ma)

Two subdivisions each form the lower, middle and late Miocene. Regionally, other systems are used.

Paleogeography

Continents continued to drift toward their present positions. Of the modern geologic features, only the land bridge between South America and North America was absent, although South America was approaching the western subduction zone in the Pacific Ocean, causing both the rise of the Andes and a southward extension of the Meso-American peninsula.

Mountain building took place in western North America, Europe, and East Asia. Both continental and marine Miocene deposits are common worldwide with marine outcrops common near modern shorelines. Well studied continental exposures occur in the North American Great Plains and in Argentina.

India continued to collide with Asia, creating dramatic new mountain ranges. The Tethys Seaway continued to shrink and then disappeared as Africa collided with Eurasia in the Turkish–Arabian region between 19 and 12 Ma. The subsequent uplift of mountains in the western Mediterranean region and a global fall in sea levels combined to cause a temporary drying up of the Mediterranean Sea (known as the Messinian salinity crisis) near the end of the Miocene.

The global trend was towards increasing aridity caused primarily by global cooling reducing the ability of the atmosphere to absorb moisture. Uplift of East Africa in the late Miocene was partly responsible for the shrinking of tropical rain forests in that region, and Australia got drier as it entered a zone of low rainfall in the Late Miocene.

Climate

Climates remained moderately warm, although the slow global cooling that eventually led to the Pleistocene glaciations continued.

Although a long-term cooling trend was well underway, there is evidence of a warm period during the Miocene when the global climate rivaled that of the Oligocene. The Miocene warming began 21 million years ago and continued until 14 million years ago, when global temperatures took a sharp drop—the Middle Miocene Climate Transition (MMCT). By 8 million years ago, temperatures dropped sharply once again, and the Antarctic ice sheet was already approaching its present-day size and thickness. Greenland may have begun to have large glaciers as early as 7 to 8 million years ago,^{[citation needed]} although the climate for the most part remained warm enough to support forests there well into the Pliocene.

Life

Life during the Miocene Epoch was mostly supported by the two newly formed biomes, kelp forests and grasslands. This allows for more grazers, such as horses, rhinoceroses,and hippos. Ninety five percent of modern plants existed by the end of this epoch.

Flora

The dragon blood tree is considered a remnant of the Mio-Pliocene Laurasian subtropical forests that are now almost extinct in North Africa.^[8]

The coevolution of gritty, fibrous, fire-tolerant grasses and long-legged gregarious ungulates with high-crowned teeth, led to a major expansion of grass-grazer ecosystems, with roaming herds of large, swift grazers pursued by predators across broad sweeps of open grasslands, displacing desert, woodland, and browsers. The higher organic content and water retention of the deeper and richer grassland soils, with long term burial of carbon in sediments, produced a carbon and water vapor sink. This, combined with higher surface albedo and lower evapotranspiration of grassland, contributed to a cooler, drier climate.^[9] C₄ grasses, which are able to assimilate carbon dioxide and water more efficiently than C₃ grasses, expanded to become ecologically significant near the end of the Miocene between 6 and 7 million years ago.^[10] The expansion of grasslands and radiations among terrestrial herbivores correlates to fluctuations in CO₂.^[11]

Cycads between 11.5 and 5 m.y.a. began to rediversify after previous declines in variety due to climatic changes, and thus modern cycads are not a good model for a "living fossil".^[12]

Fauna

Cameloid footprint (Lamaichnum alfi Sarjeant and Reynolds, 1999; convex hyporelief) from the Barstow Formation (Miocene) of Rainbow Basin, California.

Both marine and continental fauna were fairly modern, although marine mammals were less numerous. Only in isolated South America and Australia did widely divergent fauna exist.

In the Early Miocene, several Oligocene groups were still diverse, including nimravids, entelodonts, and three-toed equids. Like in the previous Oligocene epoch, oreodonts were still diverse, only to disappear in the earliest Pliocene. During the later Miocene mammals were more modern, with easily recognizable canids, bears, procyonids, equids, beavers, deer, camelids, and whales, along with now extinct groups like borophagine canids, certain gomphotheres, three-toed horses, and semiaquatic and hornless rhinos like Teleoceras and Aphelops. Islands began to form between South and North America in the Late Miocene, allowing ground sloths like Thinobadistes to island-hop to North America. The expansion of silica-rich C₄ grasses led to worldwide extinctions of herbivorous species without high-crowned teeth.^[13]

Miocene fauna of North America

Unequivocally recognizable dabbling ducks, plovers, typical owls, cockatoos and crows appear during the Miocene. By the epoch's end, all or almost all modern bird groups are believed to have been present; the few post-Miocene bird fossils which cannot be placed in the evolutionary tree with full confidence are simply too badly preserved, rather than too equivocal in character. Marine birds reached their highest diversity ever in the course of this epoch.

Approximately 100 species of apes lived during this time, ranging throughout Africa, Asia and Europe and varying widely in size, diet, and anatomy. Due to scanty fossil evidence it is unclear which ape or apes contributed to the modern hominid clade, but molecular evidence indicates this ape lived between 7 and 8 million years ago.^[14] The first hominins (bipedal apes of the human lineage) appeared in Africa at the very end of the Miocene, including Sahelanthropus, Orrorin, and an early form of Ardipithecus (A. kadabba).^[15]

In the oceans, brown algae, called kelp, proliferated, supporting new species of sea life, including otters, fish and various invertebrates.

Cetaceans attained their greatest diversity during the Miocene,^[16] with over 20 recognized genera in comparison to only six living genera.^[17] This diversification correlates with emergence of gigantic macro-predators such as megatoothed sharks and raptorial sperm whales.^[18] Prominent examples are C. megalodon and L. melvillei.^[18] Other notable large sharks were C. chubutensis, Isurus hastalis, and Hemipristis serra.

Crocodilians also showed signs of diversification during Miocene. The largest form among them was a gigantic caiman Purussaurus which inhabited South America.^[19] Another gigantic form was a false gharial Rhamphosuchus, which inhabited modern age India. A strange form Mourasuchus also thrived alongside Purussaurus. This species developed a specialized filter-feeding mechanism, and it likely preyed upon small fauna despite its gigantic size.

The pinnipeds, which appeared near the end of the Oligocene, became more aquatic. Prominent genus was Allodesmus.^[20] A ferocious walrus, Pelagiarctos may have preyed upon other species of pinnipeds including Allodesmus.

Furthermore, South American waters witnessed the arrival of Megapiranha paranensis, which were considerably larger than modern age piranhas.

Oceans

A Miocene crab (Tumidocarcinus giganteus) from the collection of the Children's Museum of Indianapolis

There is evidence from oxygen isotopes at Deep Sea Drilling Program sites that ice began to build up in Antarctica about 36 Ma during the Eocene. Further marked decreases in temperature during the Middle Miocene at 15 Ma probably reflect increased ice growth in Antarctica. It can therefore be assumed that East Antarctica had some glaciers during the early to mid Miocene (23–15 Ma). Oceans cooled partly due to the formation of the Antarctic Circumpolar Current, and about 15 million years ago the ice cap in the southern hemisphere started to grow to its present form. The Greenland ice cap developed later, in the Middle Pliocene time, about 3 million years ago.

Middle Miocene disruption

The "Middle Miocene disruption" refers to a wave of extinctions of terrestrial and aquatic life forms that occurred following the Miocene Climatic Optimum (18 to 16 Ma), around 14.8 to 14.5 million years ago, during the Langhian stage of the mid-Miocene. A major and permanent cooling step occurred between 14.8 and 14.1 Ma, associated with increased production of cold Antarctic deep waters and a major growth of the East Antarctic ice sheet. A Middle Miocene δ¹⁸O increase, that is, a relative increase in the heavier isotope of oxygen, has been noted in the Pacific, the Southern Ocean and the South Atlantic.^[21]

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

Saturday, December 26, 2015

Posted by Luboš Motl at 8:18 PM 

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 (/ˈplaɪəˌsiːn/;^[1][2] also Pleiocene) Epoch (symbol P_O^[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:

• Piacenzian (3.600–2.58 Ma)
• Zanclean (5.333–3.600 Ma)

The Piacenzian is sometimes referred to as the Late Pliocene, whereas the Zanclean is referred to as the Early Pliocene.

In the system of

• North American Land Mammal Ages (NALMA) include Hemphillian (9–4.75 Ma), and Blancan (4.75–1.806 Ma). The Blancan extends forward into the Pleistocene.
• South American Land Mammal Ages (SALMA) include Montehermosan (6.8–4.0 Ma), Chapadmalalan (4.0–3.0 Ma) and Uquian (3.0–1.2 Ma).

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.

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  The gastropod Oliva sayana, from the Pliocene of Florida.
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  The coral Cladocora from the Pliocene of Cyprus.
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  A gastropod and attached serpulid wormtube from the Pliocene of Cyprus.
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  The gastropod Turritella carinata from the Pliocene of Cyprus.
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  The thorny oyster Spondylus right and left valve interiors from the Pliocene of Cyprus.
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  Articulated Spondylus from the Pliocene of Cyprus.
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  The limpet Diodora italica from the Pliocene of Cyprus.
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  The scaphopod Dentalium from the Pliocene of Cyprus.
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  The gastropod Aporrhais from the Pliocene of Cyprus.
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  The arcid bivalve Anadara from the Pliocene of Cyprus.
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  The pectenid bivalve Ammusium cristatum from the Pliocene of Cyprus.
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  Vermetid gastropod Petaloconchus intortus attached to a branch of the coral Cladocora from the Pliocene of Cyprus.

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]

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
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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.