http://www.dpreview.com/forums/post/57962093

sooner or later. I guarantee it.

http://bigstory.ap.org/article/7006105d422740f0b4b8675c90f9a154/emails-key-security-features-disabled-clintons-server

An IT worker was forced to shut down Clinton’s server because he believed “someone was trying to hack us.” Later that day, he wrote, “We were attacked again so I shut (the server) down for a few min.” It was one of several occasions when email access to Clinton’s BlackBerry smartphone was disrupted because her private server was down, according to the documents.

The AP reported last year that in the early morning hours of Aug. 3, 2011, Clinton received infected emails, disguised as speeding tickets from New York. The emails instructed recipients to print the attached tickets. Opening an attachment would have allowed hackers to take over control of a victim’s computer.

In a blistering audit released last month, the State Department’s inspector general concluded that Clinton and her team ignored clear internal guidance that her email setup broke federal standards and could leave sensitive material vulnerable to hackers. Her aides twice brushed aside concerns, in one case telling technical staff “the matter was not to be discussed further,” the report said.

Shackles for Cankles in 2016

http://www.independent.co.uk/news/uk/home-news/eu-referendum-brexit-how-to-vote-own-pens-polling-station-polls-live-latest-mi5-conspiracy-fears-a7097011.html
In 21st century Britain surely this is unthinkable. But after being told by Dave that we could cause WWIII and Mr.Junker that it could be the end of western civilisation, amongst other lies and insults/ accusations. But no a pencil will do to VOTE OUT.
ReplyShare-2

12 hours ago
Rob32
Something doesn’t seriously add up. I have seen numerous small independent polls that have shown a huge leave landslide e.g. https://mobile.twitter.com/childcare/status/741179870915530752

I myself asked many people of all ages in my area (quite a prosperous Labour stronghold) over the last few weeks and two in three wanted leave.

http://www.dpreview.com/forums/post/57960447
http://www.dpreview.com/forums/post/57962752

Not a real surprise, considering their track record of what they’ve done in the past- which is why what Assange and Snowden did to them was exactly what they deserve and karma at its finest.

Not a real surprise, considering their track record of what they’ve done in the past- which is why what Assange and Snowden did to them was exactly what they deserve and karma at its finest.

http://www.dpreview.com/forums/post/57962556

bums at it again…

http://www.latimes.com/nation/la-na-fbi-nazi-interrogator-20160610-snap-story.html

When the FBI went looking for the best way to pry information from terrorists, they discovered it in the most unlikely of places: an almost-forgotten interrogator for Nazi Germany.

Elephant in the room – Earth entering extinction event study

1
http://www.bbc.com/news/science-environment-33209548
http://www.dpreview.com/forums/post/57893707

To be honest Brian, I don’t find his conclusions that too far fetched. I certainly don’t think we’ll be the last life form on this rock. Our mismanagement has reached unprecedented levels, and if left to continue unabated will have disastrous results. It’s folly to think we can carry on as we are without consequences. I’d rather not see the hypothesis tested.

The ongoing toxification of land, sea, and air is a dead end street. We’ve been warned, but vested interests that profit from destructive practices continue to wield great influence, that put our long term survival in doubt. That is essentially the message I get from the report.

Sadly, I think we’re quite capable of engineering our own extinction.
http://www.dpreview.com/forums/post/57897159

We can only hope. Even if the mites don’t kill the bees, they weaken them, which is causing a long term decline. Toxic crop sprays is probably the main thing affecting bees. Things like roundup (glypho360). I admit to using a bit of roundup around the house garden to keep weeds in check, but I don’t use it in my main orchards of macadamias. I do spray once or twice a year for lace bug which destroys the maccas flowers, without which I’d have no nut. That spray only works for a day though – if a lace bug lands the next day he won’t die. Usually one spray is enough to significantly dent their cycle and ensure some sort of crop.

Other macca farmers who tend to spray a lot for various pests tend to encourage bug resistance. The bug that does survive the spray regime can then run rife as their natural predators have been killed. A large farm recently got 90% of their crop destroyed by nut borer. They spray heavily. I get some nut borer, I usually get a little of all the diseases, but because I don’t spray much, my overall disease levels are low.
Be careful with that stuff, the EPA finally issued new guidelines based on emerging studies concerning toxicity. Also, weeds are becoming resistant to it so now they are trying to switch to something that is even more toxic!
http://www.dpreview.com/forums/post/57897150

TrapperJohn wrote:

Let’s look at that story a bit more in detail.

First, the authors make a completely irrelevant reference to the KT event of 65 million years ago – a comet striking the earth. That is an external event that we may or may not be able to control. We’re already looking for external masses that might strike the earth, and have tenative plans to nudge such a mass off course by detonating nuclear warheads near them. Might work, might not. In any case, that’s an irrelevant alarmist appeal – our current situation isn’t external, it is internally created. By us.

They do point to an alarming loss of species, a great deal of which, if not most, has to do with the growing human population on earth. Humans are crowding out other species. Has happened before, not just with humans but other organisms.

And it is true that humanity is approaching the limits of what the earth can support.

What can we do? Most of the western democracies already have near zero population growth. Their current population growth is largely immigration by economic refugees, who have no self imposed limit on procreation. Some of that is conditioning: they come from places that have high infant mortality, where they have lots of children so that a few might make it to maturity. Take away the infant mortality, they keep having kids at the same rate, we have a population problem.

So, what can we do? Can we enforce population limits on the third world nations that constitute most of the population growth today?

Sooner or later, it may come down to that. If the population continues to grow, we won’t have the luxury of moral debates on abortion. We may have to choose between feeding a destitute third world, or restoring the earth’s environment.

And what, in our comfortable lives, has prepared us for that eventuality?
There were other extinction events after K-T (K-P is the new name) with even more exotic causes, like gamma ray bursts and supernova explosions.

https://en.wikipedia.org/wiki/Pliocene#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.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).

https://en.wikipedia.org/wiki/Middle_Miocene_disruption

The term Middle Miocene disruption, alternatively the Middle Miocene extinction or Middle Miocene extinction peak, refers to a wave of extinctions of terrestrial and aquatic life forms that occurred around the middle of the Miocene, roughly 14.8 to 14.5 million years ago, during the Langhian stage of the Miocene.

Madelaine Bohme observed the occurrence of Varanidae, Chameleon, Cordylidae, Tomistominae, Alligatoridae, and giant turtles which indicate survival through the Miocene Climatic Optimum (18 to 16 Ma) in Central Europe (45-42°N palaeolatitude). 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. Two crocodilians of the genera Gavialosuchusand Diplocynodon were noted to have been extant in these northern latitudes prior to the permanent cooling step then became extinct 13.5 to 14 Ma.

A Middle Miocene delta18O 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.

https://en.wikipedia.org/wiki/Popigai_crater

The Popigai crater (or astrobleme) in Siberia, Russia is tied with the Manicouagan Crater as the fourth largest verifiedimpact crater on Earth. A large bolide impact created the 100 kilometres (62 mi) diameter crater approximately 35 million years ago during the late Eocene epoch (Priabonian stage). It is conjectured that it may have influenced the Eocene–Oligocene extinction event.

The crater is 300 km east from the outpost of Khatanga and 880 km (550 mi) NE of the city of Norilsk. It is designated byUNESCO as a Geopark, a site of special geological heritage. There is a small possibility that Popigai impact crater formed simultaneous with the approximately 35-million-year-old Chesapeake Bay and Toms Canyon impact craters.

For decades the Popigai crater has fascinated paleontologists and geologists, but the entire area was completely off limits because of the diamonds found there and the mines constructed by gulag prisoners under Stalin. However, a major investigatory expedition was undertaken in 1997, which greatly advanced understanding of the enigmatic structure. The impactor in this event has been identified as either an 8 km (5.0 mi) diameter chondrite asteroid, or a 5 km (3.1 mi) diameter stony asteroid.

The shock pressures from the impact instantaneously transformed graphite in the ground into diamonds within a 13.6 km (8.5 mi) radius of the impact point. These diamonds are usually 0.5 to 2 mm (0.020 to 0.079 in) in diameter, though a few exceptional specimens are 10 mm (0.39 in) in size. The diamonds not only inherited the tabular shape of the original graphite grains but they additionally preserved the original crystals’ delicate striations.

https://en.wikipedia.org/wiki/Eocene%E2%80%93Oligocene_extinction_event

The transition between the end of the Eocene and the beginning of the Oligocene is marked by large-scale extinction and floral and faunal turnover (although minor in comparison to the largest mass extinctions).Most of the affected organisms were marine or aquatic in nature. They included the last of the ancientcetaceans, the Archaeoceti.

This was a time of major climatic change, especially cooling, not obviously linked with any single major impact or any catastrophic volcanic event. One cause of the extinction event is speculated to be extended volcanic activity. Another speculation is that the extinctions are related to several large meteorite impacts that occurred about this time. One such event caused the Chesapeake Bay impact crater (40 km), and another at the Popigai crater (100 km) of central Siberia, scattering debris perhaps as far as Europe. New dating of the Popigai meteor suggests it may be a cause of the mass extinction.

A leading scientific theory on climate cooling at this time is decrease in atmospheric carbon dioxide, which slowly declined in the mid to late Eocene and possibly reached some threshold approximately 34 million years ago. This boundary is closely linked with the Oligocene Oi-1 event, an oxygen isotope excursion that marks the beginning of ice sheet coverage on Antarctica.

http://www.dpreview.com/forums/post/57901864

http://www.dpreview.com/forums/post/57901870

But by far this was the worst one:

https://en.wikipedia.org/wiki/Permian%E2%80%93Triassic_extinction_event#Combination_of_causes

The Permian–Triassic (P–Tr) extinction event, colloquially known as the Great Dying, the End Permian or the Great Permian Extinction, occurred about 252 Ma (million years) ago, forming the boundary between the Permian and Triassic geologic periods, as well as the Paleozoic and Mesozoic eras. It is the Earth’s most severe known extinction event, with up to 96% of all marine species and 70% ofterrestrial vertebrate species becoming extinct. It is the only known mass extinction of insects. Some 57% of all families and 83% of all genera became extinct. Because so much biodiversity was lost, the recovery of life on Earth took significantly longer than after any other extinction event, possibly up to 10 million years.

There is evidence for between one and three distinct pulses, or phases, of extinction. Suggested mechanisms for the latter include one or more large bolide impact events, massive volcanism, coal or gas fires and explosions from the Siberian Traps, and a runaway greenhouse effect triggered by sudden release of methane from the sea floor due to methane clathrate dissociation or methane-producing microbes known as methanogens; possible contributing gradual changes include sea-level change, increasing anoxia, increasing aridity, and a shift in ocean circulation driven by climate change.

Pinpointing the exact cause or causes of the Permian–Triassic extinction event is difficult, mostly because the catastrophe occurred over 250 million years ago, and much of the evidence that would have pointed to the cause has been destroyed by now or is concealed deep within the Earth under many layers of rock. The sea floor is also completely recycled every 200 million years by the ongoing process of plate tectonics and seafloor spreading, leaving no useful indications beneath the ocean. With the fairly significant evidence that scientists have accumulated, several mechanisms have been proposed for the extinction event, including both catastrophic and gradual processes (similar to those theorized for the Cretaceous–Paleogene extinction event). The former group includes one or more large bolideimpact events, increased volcanism, and sudden release of methane from the sea floor, either due to dissociation of methane hydrate deposits or metabolism of organic carbon deposits by methanogenic microbes. The latter group includes sea level change, increasing anoxia, and increasing aridity. Any hypothesis about the cause must explain the selectivity of the event, which affected organisms with calcium carbonate skeletons most severely; the long period (4 to 6 million years) before recovery started, and the minimal extent of biological mineralization (despite inorganic carbonates being deposited) once the recovery began.

Artist’s impression of a major impact event: A collision between Earth and an asteroid a few kilometres in diameter would release as much energy as several million nuclear weapons detonating.

Evidence that an impact event may have caused the Cretaceous–Paleogene extinction event (Cretaceous-Tertiary) has led to speculation that similar impacts may have been the cause of other extinction events, including the P–Tr extinction, and thus to a search for evidence of impacts at the times of other extinctions and for large impact craters of the appropriate age.

Reported evidence for an impact event from the P–Tr boundary level includes rare grains of shocked quartz in Australia and Antarctica; fullerenes trapping extraterrestrial noble gases; meteorite fragments in Antarctica; and grains rich in iron, nickel and silicon, which may have been created by an impact. However, the accuracy of most of these claims has been challenged. Quartz from Graphite Peak in Antarctica, for example, once considered “shocked”, has been re-examined by optical and transmission electron microscopy. The observed features were concluded to be not due to shock, but rather to plastic deformation, consistent with formation in a tectonic environment such as volcanism.

An impact crater on the sea floor would be evidence of a possible cause of the P–Tr extinction, but such a crater would by now have disappeared. As 70% of the Earth’s surface is currently sea, an asteroid or comet fragment is now perhaps more than twice as likely to hit ocean as it is to hit land. However, Earth has no ocean-floor crust more than 200 million years old because the “conveyor belt” process of seafloor spreading and subduction destroys it within that time. Craters produced by very large impacts may be masked by extensive flood basalting from below after the crust is punctured or weakened. Subduction should not, however, be entirely accepted as an explanation of why no firm evidence can be found: as with the K-T event, an ejecta blanket stratum rich in siderophilic elements (such as iridium) would be expected to be seen in formations from the time.

One attraction of large impact theories is that theoretically they could trigger other cause-considered extinction-paralleling phenomena, such as the Siberian Traps eruptions (see below) as being either an impact site or the antipode of an impact site. The abruptness of an impact also explains why more species did not rapidly evolve to survive, as would be expected if the Permian-Triassic event had been slower and less global than a meteorite impact.

Several possible impact craters have been proposed as the site of an impact causing the P–Tr extinction, including the Bedout structure off the northwest coast of Australia and the hypothesized Wilkes Land crater of East Antarctica. In each case, the idea that an impact was responsible has not been proven and has been widely criticized. In the case of Wilkes Land, the age of this sub-ice geophysical feature is very uncertain – it may be later than the Permian–Triassic extinction.

The 40 km Araguainha crater in Brazil has been most recently dated to 254.7 ± 2.5 million years ago, overlapping with estimates for the Permo-Triassic boundary. Much of the local rock was oil shale. The estimated energy released by the Araguainha impact is insufficient to be a direct cause of the global mass extinction, but the colossal local earth tremors would have released huge amounts of oil and gas from the shattered rock. The resulting sudden global warming might have precipitated the Permian–Triassic extinction event.

The final stages of the Permian had two flood basalt events. A small one, the Emeishan Traps in China, occurred at the same time as the end-Guadalupian extinction pulse, in an area close to the equator at the time. The flood basalt eruptions that produced the Siberian Traps constituted one of the largest known volcanic events on Earth and covered over 2,000,000 square kilometres (770,000 sq mi) with lava. The date of the Siberian Traps eruptions and the extinction event are in good agreement.

The Emeishan and Siberian Traps eruptions may have caused dust clouds and acid aerosols, which would have blocked out sunlight and thus disrupted photosynthesis both on land and in the photic zone of the ocean, causing food chains to collapse. The eruptions may also have caused acid rain when the aerosols washed out of the atmosphere. That may have killed land plants and molluscs and planktonic organisms which had calcium carbonate shells. The eruptions would also have emitted carbon dioxide, causing global warming. When all of the dust clouds and aerosols washed out of the atmosphere, the excess carbon dioxide would have remained and the warming would have proceeded without any mitigating effects.

The Siberian Traps had unusual features that made them even more dangerous. Pure flood basalts produce fluid, low-viscosity lava and do not hurl debris into the atmosphere. It appears, however, that 20% of the output of the Siberian Traps eruptions was pyroclastic (consisted of ash and other debris thrown high into the atmosphere), increasing the short-term cooling effect. The basalt lava erupted or intruded into carbonate rocks and into sediments that were in the process of forming large coal beds, both of which would have emitted large amounts of carbon dioxide, leading to stronger global warming after the dust and aerosols settled.

In January 2011, a team, led by Stephen Grasby of the Geological Survey of Canada—Calgary, reported evidence that volcanism caused massive coal beds to ignite, possibly releasing more than 3 trillion tons of carbon. The team found ash deposits in deep rock layers near what is now Buchanan Lake. According to their article, “coal ash dispersed by the explosive Siberian Trap eruption would be expected to have an associated release of toxic elements in impacted water bodies where fly ash slurries developed…. Mafic megascale eruptions are long-lived events that would allow significant build-up of global ash clouds.” In a statement, Grasby said, “In addition to these volcanoes causing fires through coal, the ash it spewed was highly toxic and was released in the land and water, potentially contributing to the worst extinction event in earth history.” In 2013, QY Tang reported the total amounts of important volatiles emitted from the Siberian Traps are 8.5 × 10 Tg CO2, 4.4 × 10 Tg CO, 7.0 × 10 Tg H2S and 6.8 × 10 Tg SO2, the data support a popular notion that the end-Permian mass extinction on the Earth was caused by the emission of enormous amounts of volatiles from the Siberian Traps into the atmosphere.

In 2015, evidence and a timeline indicated the extinction was caused by events in the Large Igneous Province of the Siberian Traps.

Main article: Clathrate gun hypothesisFurther information: Arctic methane release

Scientists have found worldwide evidence of a swift decrease of about 1% in the 13C/12C isotope ratio in carbonate rocks from the end-Permian. This is the first, largest, and most rapid of a series of negative and positive excursions (decreases and increases in C/C ratio) that continues until the isotope ratio abruptly stabilised in the middle Triassic, followed soon afterwards by the recovery of calcifying life forms (organisms that use calcium carbonate to build hard parts such as shells).

A variety of factors may have contributed to this drop in the 13C/12C ratio, but most turn out to be insufficient to account fully for the observed amount:

Gases from volcanic eruptions have a C/C ratio about 0.5 to 0.8% below standard (δC about −0.5 to −0.8%), but an assessment made in 1995 concluded that the amount required to produce a reduction of about 1.0% worldwide requires eruptions greater by orders of magnitude than any for which evidence has been found. (However, this analysis addressed only CO produced by the magma itself, not from interactions with carbon bearing sediments, as later proposed.)
A reduction in organic activity would extract C more slowly from the environment and leave more of it to be incorporated into sediments, thus reducing theC/C ratio. Biochemical processes preferentially use the lighter isotopes since chemical reactions are ultimately driven by electromagnetic forces between atoms and lighter isotopes respond more quickly to these forces, but a study of a smaller drop of 0.3 to 0.4% in C/C (δC −3 to −4 ‰) at the Paleocene-Eocene Thermal Maximum (PETM) concluded that even transferring all the organic carbon (in organisms, soils, and dissolved in the ocean) into sediments would be insufficient: even such a large burial of material rich in C would not have produced the ‘smaller’ drop in the C/C ratio of the rocks around the PETM.
Buried sedimentary organic matter has a C/C ratio 2.0 to 2.5% below normal (δC −2.0 to −2.5%). Theoretically, if the sea level fell sharply, shallow marine sediments would be exposed to oxidization. But 6500–8400 gigatons (1 gigaton = 10 metric tons) of organic carbon would have to be oxidized and returned to the ocean-atmosphere system within less than a few hundred thousand years to reduce the C/C ratio by 1.0%, which is not thought to be a realistic possibility. Moreover, sea levels were rising rather than falling at the time of the extinction.
Rather than a sudden decline in sea level, intermittent periods of ocean-bottom hyperoxia and anoxia (high-oxygen and low- or zero-oxygen conditions) may have caused the C/C ratio fluctuations in the Early Triassic; and global anoxia may have been responsible for the end-Permian blip. The continents of the end-Permian and early Triassic were more clustered in the tropics than they are now, and large tropical rivers would have dumped sediment into smaller, partially enclosed ocean basins at low latitudes. Such conditions favor oxic and anoxic episodes; oxic/anoxic conditions would result in a rapid release/burial, respectively, of large amounts of organic carbon, which has a low C/C ratio because biochemical processes use the lighter isotopes more. That or another organic-based reason may have been responsible for both that and a late Proterozoic/Cambrian pattern of fluctuating C/C ratios.
Other hypotheses include mass oceanic poisoning releasing vast amounts of CO and a long-term reorganisation of the global carbon cycle.

Prior to consideration of the inclusion of roasting carbonate sediments by volcanism, the only proposed mechanism sufficient to cause a global 1% reduction in theC/C ratio was the release of methane from methane clathrates,. Carbon-cycle models confirm that it would have had enough effect to produce the observed reduction. Methane clathrates, also known as methane hydrates, consist of methane molecules trapped in cages of water molecules. The methane, produced by methanogens (microscopic single-celled organisms), has a C/C ratio about 6.0% below normal (δC −6.0%). At the right combination of pressure and temperature, it gets trapped in clathrates fairly close to the surface of permafrost and in much larger quantities at continental margins (continental shelves and the deeper seabed close to them). Oceanic methane hydrates are usually found buried in sediments where the seawater is at least 300 m (980 ft) deep. They can be found up to about 2,000 m (6,600 ft) below the sea floor, but usually only about 1,100 m (3,600 ft) below the sea floor.

The area covered by lava from the Siberian Traps eruptions is about twice as large as was originally thought, and most of the additional area was shallow sea at the time. The seabed probably contained methane hydrate deposits, and the lava caused the deposits to dissociate, releasing vast quantities of methane. A vast release of methane might cause significant global warming since methane is a very powerful greenhouse gas. Strong evidence suggests the global temperatures increased by about 6 °C (10.8 °F) near the equator and therefore by more at higher latitudes: a sharp decrease in oxygen isotope ratios (O/O); the extinction of Glossopteris flora (Glossopteris and plants that grew in the same areas), which needed a cold climate, with its replacement by floras typical of lower paleolatitudes.

However, the pattern of isotope shifts expected to result from a massive release of methane does not match the patterns seen throughout the early Triassic. Not only would such a cause require the release of five times as much methane as postulated for the PETM, but would it also have to be reburied at an unrealistically high rate to account for the rapid increases in the C/C ratio (episodes of high positive δC) throughout the early Triassic before it was released again several times.

See also: Anoxic event

Evidence for widespread ocean anoxia (severe deficiency of oxygen) and euxinia (presence of hydrogen sulfide) is found from the Late Permian to the Early Triassic. Throughout most of the Tethys and Panthalassic Oceans, evidence for anoxia, including fine laminations in sediments, small pyrite framboids, high uranium/thorium ratios, and biomarkers for green sulfur bacteria, appear at the extinction event. However, in some sites, including Meishan, China, and eastern Greenland, evidence for anoxia precedes the extinction. Biomarkers for green sulfur bacteria, such as isorenieratane, the diagenetic product of isorenieratene, are widely used as indicators of photic zone euxinia because green sulfur bacteria require both sunlight and hydrogen sulfide to survive. Their abundance in sediments from the P-T boundary indicates hydrogen sulfide was present even in shallow waters.

This spread of toxic, oxygen-depleted water would have been devastating for marine life, producing widespread die-offs. Models of ocean chemistry show that anoxia and euxinia would have been closely associated with hypercapnia (high levels of carbon dioxide). This suggests that poisoning from hydrogen sulfide, anoxia, and hypercapnia acted together as a killing mechanism. Hypercapnia best explains the selectivity of the extinction, but anoxia and euxinia probably contributed to the high mortality of the event. The persistence of anoxia through the Early Triassic may explain the slow recovery of marine life after the extinction. Models also show that anoxic events can cause catastrophic hydrogen sulfide emissions into the atmosphere (see below).

The sequence of events leading to anoxic oceans may have been triggered by carbon dioxide emissions from the eruption of the Siberian Traps. In that scenario, warming from the enhanced greenhouse effect would reduce the solubility of oxygen in seawater, causing the concentration of oxygen to decline. Increased weathering of the continents due to warming and the acceleration of the water cycle would increase the riverine flux of phosphate to the ocean. The phosphate would have supported greater primary productivity in the surface oceans. The increase in organic matter production would have caused more organic matter to sink into the deep ocean, where its respiration would further decrease oxygen concentrations. Once anoxia became established, it would have been sustained by a positive feedback loop because deep water anoxia tends to increase the recycling efficiency of phosphate, leading to even higher productivity.

A severe anoxic event at the end of the Permian would have allowed sulfate-reducing bacteria to thrive, causing the production of large amounts of hydrogen sulfide in the anoxic ocean. Upwelling of this water may have released massive hydrogen sulfide emissions into the atmosphere and would poison terrestrial plants and animals and severely weaken the ozone layer, exposing much of the life that remained to fatal levels of UV radiation. Indeed, biomarker evidence for anaerobic photosynthesis by Chlorobiaceae (green sulfur bacteria) from the Late-Permian into the Early Triassic indicates that hydrogen sulfide did upwell into shallow waters because these bacteria are restricted to the photic zone and use sulfide as an electron donor.

The hypothesis has the advantage of explaining the mass extinction of plants, which would have added to the methane levels and should otherwise have thrived in an atmosphere with a high level of carbon dioxide. Fossil spores from the end-Permian further support the theory: many show deformities that could have been caused by ultraviolet radiation, which would have been more intense after hydrogen sulfide emissions weakened the ozone layer.

Map of Pangaea showing where today’s continents were at the Permian–Triassic boundary

About halfway through the Permian (in the Kungurian age of the Permian’s Cisuralian epoch), all the continents joined to form the supercontinent Pangaea, surrounded by the superocean Panthalassa, although blocks that are now parts of Asia did not join the supercontinent until very late in the Permian. The configuration severely decreased the extent of shallow aquatic environments, the most productive part of the seas, and it exposed formerly isolated organisms of the rich continental shelves to competition from invaders. Pangaea’s formation would also have altered both oceanic circulation and atmospheric weather patterns, creating seasonal monsoons near the coasts and an arid climate in the vast continental interior.

Marine life suffered very high but not catastrophic rates of extinction after the formation of Pangaea (see the diagram “Marine genus biodiversity” at the top of this article), almost as high as in some of the “Big Five” mass extinctions. The formation of Pangaea seems not to have caused a significant rise in extinction levels on land, and, in fact, most of the advance of thetherapsids and increase in their diversity seems to have occurred in the late Permian, after Pangaea was almost complete. Thus, it seems likely that Pangaea initiated a long period of increased marine extinctions but was not directly responsible for the “Great Dying” and the end of the Permian.

A hypothesis published in 2014 posits that a genus of anaerobic methanogenic archaea known as Methanosarcina was responsible for the event. Three lines of evidence suggest that these microbes acquired a new metabolic pathway via gene transfer at about that time, enabling them to efficiently metabolize acetate into methane. That would have led to their exponential reproduction, allowing them to rapidly consume vast deposits of organic carbon that had accumulated in the marine sediment. The result would have been a sharp buildup of methane and carbon dioxide in the Earth’s oceans and atmosphere, in a manner that may be consistent with the C/C isotopic record. Massive volcanism facilitated this process by releasing large amounts of nickel, a scarce metal which is a cofactor for an enzymes involved in producing methane. On the other hand, in the canonical Meishan sections, the Nickel concentration increases somewhat after the δC concentrations have begun to fall.

Possible causes supported by strong evidence appear to describe a sequence of catastrophes, each worse than the last: the Siberian Traps eruptions were bad enough alone, but because they occurred near coal beds and the continental shelf, they also triggered very large releases of carbon dioxide and methane. The resultant global warming may have caused perhaps the most severe anoxic event in the oceans’ history: according to this theory, the oceans became so anoxic, anaerobic sulfur-reducing organisms dominated the chemistry of the oceans and caused massive emissions of toxic hydrogen sulfide.

However, there may be some weak links in this chain of events: the changes in the C/C ratio expected to result from a massive release of methane do not match the patterns seen throughout the early Triassic; and the types of oceanic thermohaline circulation that may have existed at the end of the Permian are not likely to have supported deep-sea anoxia.

http://www.dpreview.com/forums/post/57901876

this is fascinating stuff

https://en.wikipedia.org/wiki/Wilkes_Land_crater

A giant impact crater beneath the Wilkes Land ice sheet was first proposed by R. A. Schmidt in 1962 on the basis of the seismic and gravity discovery of the feature made by the U.S. Victoria Land Traverse in 1959–60 (VLT), and the data provided to Schmidt by J. G. Weihaupt, geophysicist of the VLT (Geophysical Studies in Victoria Land, Antarctica, Report No. 1, Geophysical and Polar Research Center, University of Wisconsin, 1–123). Schmidt further considered the possibility that it might be the elusive source of tektites from the Australasian strewnfield.

EGM2008 gravity anomaly map

The hypothesis was detailed in a paper by J. G. Weihaupt in 1976. Evidence cited included a large negative gravity anomaly coincident with a subglacial topographic depression 243 kilometres (151 mi) across and having a minimum depth of 848 metres (2,782 ft).

The claims were challenged by C. R. Bentley in 1979. On the basis of a 2010 paper by J. G. Weihaupt et al., Bentley’s challenge was proven to be incorrect, and the Earth Impact Database (Rajmon 2011) has now reclassified the Wilkes Land Anomaly from a “possible impact crater” to a “probable impact crater” on the basis of Weihaupt et al.’s paper. Several other potential impact crater sites have now been proposed by other investigators in the Ross Sea, West Antarctica, and the Weddell Sea.

Map of Antarctica showing Wilkes Land, with the crater conjectured by von Frese and team marked in red

The Wilkes Land mass concentration (or mascon) is centered at 70°S 120°ECoordinates

70°S 120°E and was first reported at a conference in May 2006 by a team of researchers led by Ralph von Frese and Laramie Potts of Ohio State University.

The team used gravity measurements by NASA’s GRACE satellites to identify a 300 km (190 mi) wide mass concentration and noted that this mass anomaly is centered within a larger ring-like structure visible in radar images of the land surface beneath the Antarctic ice cap. This combination suggested to them that the feature may mark the site of a 480 km (300 mi) wide impact crater buried beneath the ice and more than 2.5 times larger than the 180 km (110 mi) Chicxulub crater.

Due to the site’s location beneath the Antarctic ice sheet there are no direct samples to test for evidence of impact. There are alternative explanations for this mass concentration, such as formation by a mantle plume or other large-scale volcanic activity. If this feature really is an impact crater then, based on the size of the ring structure, it has been suggested by von Frese’s team that the impactor could have been four or five times wider than the one that created the Chicxulub, believed to have caused the Cretaceous–Paleogene extinction event.

Because mass concentrations on Earth are expected to dissipate over time, von Frese and coworkers believe the structure must be less than 500 million years old, and also note that it appears to have been disturbed by therift valley that formed 100 million years ago during the separation of Australia from the Gondwanasupercontinent.

These researchers therefore speculate that the putative impact and associated crater may have contributed to this separation by weakening the crust at this location. These bracketing dates also make it possible that the site could be associated with the Permian–Triassic extinction event. The Permian–Triassic extinction occurred 250 million years ago, and is believed to be the largest extinction event since the origin of complex multicellular life.

Plate reconstructions for the Permian–Triassic boundary place the putative crater directly antipodal to the Siberian Traps, and von Frese et al. (2009) use the controversial theory that impacts can trigger massive volcanism at their antipodes to bolster their impact crater theory.

However, there are already other suggested candidates for giant impacts at the Permian–Triassic boundary, for example Bedout off the northern coast of Western Australia, although all are equally contentious, and it is currently under debate whether or not an impact played any role in this extinction.

The complete absence of a well-defined impact ejecta layer associated with the Permian–Triassic boundary at its outcrops within Victoria Land and the centralTransantarctic Mountains argues against there having been any impact capable of creating a crater the size of the hypothesized Wilkes Land impact crater within Antarctica at the Permian–Triassic boundary.
http://www.dpreview.com/forums/post/57897180

Funny no one commented on my post that I made in a different thread about this, this is an issue I’ve been talking about for several years.

http://www.dpreview.com/forums/post/57895060

greed, desire for power, fear, violence, and other instant gratification foibles are indeed a part of the human persona- one might say they are a part of nature itself- and it’s why dominant species eventually go extinct when they use up their natural resources.

It got me thinking that this might be a built in kill-switch in the planetary biome. Nature, the planet, whatever you want to call it, likes diversity and dominance is at direct odds with that. So, at some moment, a tipping point is reached, and when the planet has had enough all those things that helped a species become dominant, eventually leads to its destruction. And diversity once again wins out and nature moves on.

As I’ve mentioned several times before, the only way I feel to get out of this vicious cycle is to eventually leave the planet itself.

Oh and I don’t think racism or bigotry amongst humans will be wiped out until we find another sentient species and then we will focus our intolerance on them instead.

http://www.dpreview.com/forums/post/57901790

The odd thing is that, like many things individually discussed as having worldwide consequences, overpopulation is an issue which could be discussed with possible ways to address the very real issue. But, it seems that it is a verboten topic to be taken seriously either by agencies in the worldwide governing bodies in the U.N. or even at a more nationally local way. But the overall consequences are very clear and are the obvious driving factor in all other issues.
Population growth will eventually flatten out, the only question is when- I think that’s what will determine what happens to us. I’ve seen different UN projections, the average of them seems to indicate it might happen by the year 2200.

The odd thing is that, like many things individually discussed as having worldwide consequences, overpopulation is an issue which could be discussed with possible ways to address the very real issue. But, it seems that it is a verboten topic to be taken seriously either by agencies in the worldwide governing bodies in the U.N. or even at a more nationally local way. But the overall consequences are very clear and are the obvious driving factor in all other issues.
Population growth will eventually flatten out, the only question is when- I think that’s what will determine what happens to us. I’ve seen different UN projections, the average of them seems to indicate it might happen by the year 2200.

As I’ve mentioned several times before, the only way I feel to get out of this vicious cycle is to eventually leave the planet itself.

http://www.dpreview.com/forums/post/57962403

The thing is, human beings have a lack of a proper framework for how fragile their existence truly is. Sure, we get all in a panic after the latest “terrorist” attack, but viewing humanity from the proper “larger picture” perspective, you realize that humanity is just one more cog in the wheel and very small changes to our biosphere can have very large consequences. And technology won’t be able to save us either (at least not at its current stage of development)- if we have one of these ELE- if we don’t go extinct, we’ll go right back to the primal stage.

PS colonizing space is going to be our last best option before we let things get that far.

http://www.dpreview.com/forums/post/57962385

William Carson wrote:

http://www.bbc.com/news/science-environment-33209548

Not really much to discuss – Three Universities released results of study.
https://en.wikipedia.org/wiki/South_Polar_dinosaur

During the Cretaceous, Earth on average was warmer than it is now, making the polar regions more habitable.

Several techniques have been used to deduce the ancient climate of Gondwana in the Early Cretaceous. One technique involves looking at the levels of oxygenisotopes in the rocks from the time. These have suggested estimated mean annual temperatures of between 0 and 8 °C (32 and 46 °F). The rocks with associatedmammal and dinosaur fossils show evidence of permafrost, features such as ice wedging, patterning and hummocked ground. Permafrost today occurs in temperature ranges of between −2 and 3 °C (28 and 37 °F).

Another method used to deduce the climate of the time is to use the types of plants found in the fossil record. The fossil record shows a floral community dominated by conifers, ginkgoes, ferns, cycads, bryophytes, horsetails and a few flowering plants. The plants indicated, through structural adaptations, a seasonal cold period and a mean annual temperature around 10 °C (50 °F) (higher than found by the oxygen isotope data) and the presence of ferns and bryophytes indicates rainy conditions. A large inland sea that extended into central Australia modified its continental climate.

The very lopsided distribution of land and ocean around the South Pole would have forced the ocean currents and seasonal winds (monsoons) to flow across the polar area, stopping a cold pool from forming around the pole.

These studies show that during the Cretaceous there were no polar ice caps, and forests would have extended all the way to the South Pole, and life could have flourished there during the summer. However, the Earth’s axial tilt means that the regions inside the Antarctic circle would still have experienced a polar night: a period of sunless darkness and cold of up to six months, during which only the hardiest life forms could survive. This combination of a habitable terrain with a long polar night is an ecological circumstance that has no present day analogue.

They also talk about the possibilities of small dinosaurs surviving there up to half a million years after the K-T event because they were already adapted to the colder climate.

And on the colonizing space front, looks like the first human mission to mars is scheduled for 2020.

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