How long would it take for earth's core to cool down and solidify?

At what rate is the earth's core cooling down?

The inner core is cooling at the rate of around $55^{\circ} C$ every billion years.

  Would earth go the same way as Mars by first losing its magnetic field followed by its atmosphere as its core solidifies and cools down ?

Given enough time, yes; But earth is constantly producing heat though multiple processes, the most important being the decay of radioactive elements with long half lives (for e.g., U-238 has a half life of around 4.5 billion years). As the present temperature of the inner core is estimated to be around  $5000^{\circ} C$, this is going to take tens of billions of years.

The magnetic fields are generated by eddy currents in the outer core, which is a liquid layer about 2,300 km thickness. The inner core is growing at the rate of about 1 mm per year, so it is going to 'freeze over' (i.e. solidify) in about 2.3 billion years. Without its liquid outer core, the Earth's magnetic field shuts down, and charged particles emanating from the Sun gradually deplete the atmosphere, like Mars.

  Is it slow enough?

Well, it is not slow enough for the sun to become a red giant and fry earth, which will happen in 4 billion years or so. But is certainly doesn't matter as we won't be around to witness it.


Does clearing snow contribute to climate change?

Urban areas, where most snow clearing is done, are heat islands already, so it would be tough to disentangle the effect of clearing snow off roads.  Whitewashing black asphalt is one of the strategies being tried to reduce the heat effect in the summer, though, and black asphalt is seen as a big factor in heat islands, so it seems reasonable that exposing black pavement in winter would also have some impact, but detailed studies so far have mostly focussed on deadly summer heat, not winter effects.


The Earth's equator is about 0.006% closer to the sun than the Earth's mean spin axis, so the effect of proximity to the sun on daylight hours is so small that my calculator - which has a register of 10 significant figures - can't even discern any difference. A rough back of an envelope hand calculation indicates less than a millionth of a second difference in daylight hours between equator and the Earth's mean spin axis. So the effect on the weather would be indeterminate, and vastly less than caused by orbital variations, solar storms, fluctuations in solar luminosity, seasonal cloud variation, etc.


Given there is no raised rim around the hole, it is not meteorite crater.

It is difficult to be certain given the perspective view in the picture, but it appears to be sink hole, also known as a subsidence hole. More pictures of the area & even an aerial view would help significantly.

If the region has a history of underground mining, the hole may be due to the collapse of underground openings resulting in subsidence on the surface.

If the is no history of mining in the region then an opening may have been created underground, by subterranean water sources and the surface material has subsided or sunk into the hole.

Another possibility is that the hole is a bomb crater produced by the military. This could occur if the site was used as a bombing range by the Turkish air force. Also, given the proximity of the area to Kurdish regions, another possibility is that a bomb could have been dropped during a battle with Kurdish or similar forces.


No water flows out of it, apparently...

https://www.onlyinyourstate.com/wyoming/continental-divide-basin-wy/

In summary, there used to be a big lake there, now its a basin with no flows into either ocean. Water there seems to be self contained, accumulating from rainfall and removed by evaporation.


For sure this is not available.

To create those maps takes several dozens Earth orbits by GOCE (one orbit ~90 minutes) and possibly many more to bring up the signal to noise
Which gravitational features would you expect to vary significantly on any human timescale, so that creating such a scan would make sense?

This does not mean however, that no gravitational changes over time can be detected. ESA produced a video visualising data that showcases how GRACE and GOCE worked to produce ~10 snapshots per year from 2009-2012 to measure Antarctic ice loss. So continuing your search along those lines will surely lead to positive results.


The simple answer: Because it is.

There's a nice theory that explains why the rotation axis of a big gas giant is more or less coaligned with its orbital angular momentum vector. Those big gas giants form somewhat like a snowball rolling downhill becomes bigger and bigger and bigger. This doesn't apply to rocky planets, let alone lesser gas giants and ice giants. Saturn's rotation axis is inclined by 27°, Uranus by 98°, Neptune by 30°. It's a bit random.

With regard to the rocky planets, whatever rotation Mercury had in the distant past is long lost. Tidal interactions with the Sun will necessarily have locked Mercury into a resonance between rotation and orbital rotations. That the resonance is 3:2 rather than 1:1 is a result of the largish eccentricity of Mercury's orbit.

Mars is not tidally locked, but it's obliquity is notoriously chaotic. A number of past and future recreations of Mars' rotation show chaotic behavior. Whatever rotation Mars had when it formed has long been lost thanks to that chaos. The obliquity of Mars has gone through huge changes over the last few billion years, occasionally changing rapidly, occasionally remaining stable. That's the nature of chaos.

Venus also isn't tidally locked per se, but essentially it is. The rotation of Venus is rather bizarre. The solid part of the planet rotates retrograde at a very slow rate. On the other hand, the upper parts of Venus' thick atmosphere rotate prograde. The combined rotation represents one of the four final states in which Venus as a whole can rotate (multiple articles by Laskar, and by others). Venys is in its final rotational state.

The Earth is a marked exception amongst the rocky planets. The key to that marked exception is our exceptionally massive moon. The Earth's moon acts to stabilize the Earth's rotation. Whatever obliquity the proto-Earth had prior to the giant impact is long lost. On the other hand, the obliquity after that giant impact has remained fairly constant thanks to that stabilizing influence.


How do the various types of clouds affect the atmosphere below them in a polluted environment?

I haven't found proper references yet, but this hasn't gotten an answer yet. To speculation!

Long-lived (non-precipitating) clouds can decrease solar insolation at the surface, reducing convection and mixing below the cloud and increasing pollutant concentrations. If clouds are just a symptom of a high-humidity environment, that can promote the condensation of semi-volatile species into particulates (nitrate, ammonia, some organics) if you don't count phase change as a reaction. Convective storms are associated with a lot of mixing, both within the boundary layer and between the boundary layer and the free troposphere, reducing concentrations.

Without the photolysis or rainout processes, I don't know enough about different cloud types and environments to speculate further. I'm hoping this at least sparks more discussion.


Donation Options for Fossil and Mineral Collection

I work for an university collection and wo often deal with donations. If you contact a museum or university collection, be prepared for the following questions:

How many fossils are approximately included in the collection?
How were they acquired? Were they bought on fossil fairs? Were they self collected?
What's the weight of the collection? Sounds weird, but this is important for storage calculation.
Is there a list including all specimen?
Are all objects properly identified and labeled? This includes the following information: Find locality, Genus, if possible species, geological time including finer stratigraphy. Examples: Diplodocus carnegie, Upper Jurassic, Morrison Formation, Wyoming or Kallokibotion bajazidi, Upper Cretaceous, Maastrichtian, Sanpetru, Romania. The more information, the better!

Why are these questions so important? If you want the objects to be "hands-on" for example for students studying these objects, they have to be properly identified. No student or researcher can work with "trilobite of unknown age and source". All collections provide hands-on research for those who request it. We do the same. I have a lot of guests coming to our collection wanting to see Triassic ichtyhosaurs, golden ammonites from Opalinus Clay or anything else. In this cases, I prepare all fossils for hands-on access.

In your case, I would recommend the Paleontological Collection of the Indiana University. The collection is quite famous, often visited, and has a very good recommendation all over the world.

See here for their webpage


How do we know how much Uranium was in any given sample when it was deposited?

The chemistry of lead is very different from that of uranium and thorium. There are key kinds of rock that could not possibly have been formed with even the smallest amount of primordial lead. The lithophilic nature of uranium and thorium means that those same kinds of rock could easily have readily accepted primordial uranium or thorium.

Any lead in those kinds of rocks must necessarily be the result of decay of uranium or thorium after the rock formed.


How is it possible that a Hurricane such as Alex forms in the Atlantic in winter?

Alex was an out of season freak event that bucked the trend and broke all the rules. As hurricanes go, it was somewhat weak, and could never have strengthened beyond category 1. Three conditions made it happen (i) there was an unusually strong vortex over Cuba which kick-started the rotation, (ii) the high level atmospheric shear, which usually kills off fledgling hurricanes, just didn't appear on this occasion, (iii) the storm initially followed the Gulf Stream Drift, and hence gained energy from higher than usual sea surface temperatures - though still a lot cooler than normal. After the hurricane reached central north Atlantic it veered off to the northwest, where it met much colder sea-surface temperatures. It was this cold water that killed it off.


Why does the emission of aircrafts at higher altitudes have a greater effect on the climate?

Initial theories of the atmosphere assumed that it was "well mixed". You will see that term mentioned in many articles, and also the fairly made point that it is an assumption. Historical measurements of CO2 concentration had been pretty sporadic with the exception of Mauna Loa. It's instructive to look at the raw data from that observatory and the adjustments made to produce a smooth curve to view changes year by year. Note also the daily variations due to plants. A NASA satellite was launched in 2014 to measure CO2 high in the atmosphere so there is now evidence CO2 is not well mixed but we do not have enough data to look at long term trends as it has not given us even 3 years worth of data yet.
It seems to be claimed that about 40% of the CO2 produced from burning fossil fuels comes to show itself as CO2 concentration increases. The rest must go somewhere else (or we got the calculation wrong !). It is often assumed 30-40% goes into the oceans. Although I have seen claims that the earth has greened by about 18% in the past 40 years (increased intensive agriculture) I have not seen the increased CO2 from this source taken into account yet in calculating which proportion of the CO2 increase in the atmosphere is due to that. At a first examination this would seem to be quite important. If the 18% greening is responsible for a significant percentage of CO2 increase then clearly fossil fuel CO2 is less important. This looks like an important area that needs to be looked at. Maybe careful study of satellite data over green areas compared to deserts/ice will reveal something.


You are right, you can't get cloudbase height without 3D data. You can do that using radiosondes. However, if your weather station has a ceilometer, then you don't actually need many calculations. However, they are usually quite expensive.

If you want a real rough calculation, you can just use the Lifted Condensation Level, which is more valid estimate during the day than at night.

Note on the grib files: They may not always have all of the variables. For example, the WAVE ocean model (see NCEP NOMADS) won't have cloud base, because it is in fact for oceans. However, what you can do is use models like the GFS, which tell you what model levels have clouds, and then find the height of the lowest level that has cloud cover. It will take some programming though.


Are certain isobar temperatures higher in mountainous regions?

Well, if there were no other factors, the temperature at the same isobar should be the same all over the Earth. But there are other factors, like winds, air mixing, albedo, ocean currents etc.

The temperature in atmosphere is lower at higher altitudes. That's because the air is gas, and it compresses. So the air at ocean level is denser than the air at 10km height. The air heats from the ground, and when it's getting warmer, it goes up. But because there is lower pressure, it expands, and while it's expanding, it cools down. That's why the higher you go - the colder it is. But if the pressure is not changing, the temperature shouldn't change too.


Would a Biorock formed buiding be suitable for ocean floor research?

I suspect the answer is no. The reason is that underwater constructions typically are supposed to be air- and water-tight, and to have strength enough to resist pressure differences. Biorock looks like it is naturally porous, so it would not be particularly good at holding water out. While the compression strength is like concrete, you really want to guarantee the solidity if you have humans in it.

Basically, risk and uncertainty is a cost too. It is often worth paying extra to know what a structure can handle. So hence it might just be easier to use underwater concrete, where there is likely far more standardised quality.

(Still, biorock is cool and will presumably in due time be well understood enough to compete with a lot of materials and methods.)


What has been the influence of the moon on Earth's temperature?

The complications of calculating the moon's contributions to earth's heat budget are touched on in Emergence of a Habitable Planet (2007) by Zahnle, et.al. in Space Science Reviews, a paper trying to determine   when in earth's history the planet's surface would become cool enough to support life. The portion of the paper that relates to tidal heating suggests that the early moon contributed substantially to the interior heat of the earth system for about 1.2 million years, but as the moon's orbit widened, the earth cooled and solidified, and water condensed into oceans, the moon's contributions gradually became minimal.

  Viscous damping of tidal motions generates heat. Therefore tidal
  heating occurs most strongly in materials that are solid but close to
  melting. This introduces the possibility of a governing feedback that
  works through the dependence of viscosity on temperature. If tidal
  dissipation exceeds what the atmosphere can radiate, the excess heat
  raises the temperature, which lowers the viscosity, which in turn
  lowers the rate of tidal dissipation. This looks like a stable
  feedback. It follows that, while tidal dissipation was important, the
  base of the mantle was solid but the rest of it was fluid, and tidal
  heating generated almost all of the thermal energy radiated to space.
  In the limit of an asymptotically thick steam atmosphere, tidal
  dissipation would have been regulated to generating heat at the
  runaway greenhouse limit of ∼140 W/m2.

In a caption for a figure the authors also note:

  Tidal heating plays an important role in prolonging the magma ocean.
  Tidal forcing wanes as the Moon evolves away from the Earth.
  Thereafter heat flow is controlled by convection of the solid mantle.
  By 4.4 Ga the global average heat flow would have been ∼0.5 W/m2.
  Later in the Hadean typical heat flows would have been 0.2–0.3 W/m2,
  not enormously larger than what they are now. For comparison heat flow
  today is 0.065 W/m2 through the continents and 0.1 W/m2 through the
  ocean crust.


There are no plate faults in Arizona (actually "plate boundary" is the term that we use - "fault" already has a different meaning, so it could be confusing), but there is still extension of the continental crust. The southern half of Arizona has part of the Basin & Range province, which stretches from Oregon to the south of Mexico.

If you imagine holding a peice of slightly brittle rubber and having someone push up from beneath it, you get cracks in the rubber where it stretches. This is happening to the North American continent. The 'ranges' in "Basin & Range" are the ridges in the rubber, the 'basins' are the cracks. (Exactly why/how this part of North America was pulled apart/pushed up is a subject of intense debate among geologists.)

You can intuitively see how these ranges would not be as high as the Rockies, which formed from a plate of oceanic crust (denser, heavier, thinner) being pulled/pushed underneath the contnental crust (lighter, fluffier, much thicker), causing continental rock to A) bunch up, and B) melt as water is added to it, leading to magma rising and bulging upward into volcanic chains. (Another factor controlling mountain height is erosion, so the Rockies, which are 80 million years old, are lower than the Andes, which are formed a similar way, but which are still being pushed upwards.)

The Himalayas are different again - instead of oceanic crust meeting contnental crust, this was contnental crust meeting more contnental crust, so instead of one side going underneath another, neither side will sink, they're both too light, so they cram into each other creating much higher mountains than either the Rockies or the Andes.

Just doing some quick googling, it sounds like Arizona also has both volcanic feature and eroded remnants of volcanic features. These kinds of mountains/hills are formed via a different method again, and their heights are controlled by their own method of formation. Volcanoes can vary a lot in height. They can be very small, like the volcanoes in south-east Australia where I live, or very large, like the volcanoes in the Andes mountain range, or they can be large, but broad and flat, like Hawai'i.

Erosion can carve out softer rock and leave behind more resistant stuff, and this is how some smaller hills/mountains are formed (like Uluru in central Australia). I found this online which might lead you in some interesting directions: Geologic History of Arizona By Jan C. Rasmussen


Why is this "independently reproducible proof of non-curvature" wrong?

The biggest flaw I see in a cursory look at this work is failure to compensate for atmospheric refraction.  Density varies in the atmosphere enough that the refractive index varies.  At low angles above the horizon the temperature structure of the atmosphere becomes very important in determining optical refraction and at low angles very close to the ground it becomes extremely important.

When cool air is at the surface and warms with height (e.g. a temperature inversion), which is likely above a cool body of water like a canal (or in winter, or at night and early morning), the resulting density gradient causes light to bend toward the ground.  This means whatever you are observing is actually lower than you perceive it.

http://images.tutorvista.com/content/light-refraction/looming.jpeg

In the situation where it is warm near the surface and cools aloft you get the opposite and light bends up toward the sky.  This gives rise to the water mirages you can see on hot days on roads or sand (where there is a very strong temperature gradient with height).


How will air quality, weather and climate improve because of the containment, social distancing and lockdown during the COVID-19 outbreak?

This is a topic of almost continual discussion in the South China Morning Post, scmp.com , an English language newspaper in Hong Kong. This is both because air quality is a major problem in China (but one to which they are paying a good deal of attention) and because massive economic interruptions are relatively frequent. The Olympics were a big one, national festivals like Spring Festival, 春节, Chūn jié, give readers a chance to mourn or hope, the current trade war modulates the scale of industry, and now we have Covid-19.

Obviously the virus crisis is bringing about great improvement in current air quality almost everywhere. I doubt that any climatic effects are known yet.

Here's an article which introduces the topic in China -- which is, after all, the major live experiment going on: https://www.scmp.com/news/china/society/article/3044747/beijings-air-quality-shows-significant-improvements-war


What would happen to the Earth if there were no seasons?

In a short timescale, let's say one or two years after a permanent equinox state, the temperature would be basically the current mean annual temperature. This is because if we take the premise of keeping heat transport by convection (on the sea and the atmosphere) as it it today, the total energy inputs and outputs would be the same. Therefore, the same mean annual temperature would occur but without seasonal variability.

To simplify things, let's use a simple model of temperature v/s latitude (that will also be useful in the discussion later):

Image originally from The Petroleum System Blog

Using that formula, the temperature at the poles (reduced to sea level) would be -16.8 °C (from the figure actual data points it can be seen that in real life the south pole is much colder than the north pole).

Now, the previous assumptions contradicts the requirement of "equilibrium", because the above scenario is far from steady state.

So now I will go on to try to describe what would happen to Earth's climate in your hypothetical scenario:

One thing that we learned by studying how the Milankovitch cycles trigger and reverse Pleistocene ice ages, is that to initiate an ice age cold winters are not necessary, what is needed are cold or mild summers.
Currently, the inclination of Earth axis (a.k.a. obliquity) varies between 22° and 24.5° , with a mean period of 41,040 years. When the inclination is 22°, mild summers occur and, therefore, the perfect condition to initiate an ice age (specially when combined with other ad-hoc orbital conditions). The permanent equinox situation you propose, is equivalent to an obliquity of 0°, that would lead to the coldest possible summer (this is, no summer at all). Therefore, such condition would set the Earth on track for an intense and never-ending ice age.

Let me explain how this could work: Using the formula above, the temperatures would be permanently below zero between the poles and latitudes 58.3°. Therefore, snow would start to accumulate in those areas, building an ice sheet and once the ice sheet gets thick enough it would start flowing outwards.

Figure from Lumen Learning.

The ice sheet then becomes self-sustaining due to two positive feedbacks:

Due to its high albedo, it would reflect most of the solar radiation back to the space, cooling down the Earth.
As the ice sheet advance, its thickness adds to the elevation of the terrain, therefore the surface is higher and colder, allowing snowfall beyond the 58.3° of latitude. The thicker it grows the more it can advance towards the equator.

Therefore, the polar ice sheets and their floating extensions (ice shelves), would slowly take over the Earth, and bring it to a state like the  Snowball Earth hypothesis that proposes that Earth surface's became entirely or nearly entirely frozen at least once, sometime earlier than 650 Mya (million years ago).

In your scenario, the equator would constantly receive maximum solar irradiation, therefore, perhaps it could be spared by the ice sheets, but you would need to run a model to figure that out.

But if we assume that the ice sheets would engulf the whole planet, it is easy to calculate the Earth's effective radiative temperature, that is equivalent to the mean temperature. To avoid going into the math (that is quite simple anyway), we can use the Indiana University's Planet Temperature Calculator, that shows that if we crank Earth's albedo from the current 29% to a 80% (a reasonable figure for snow), the mean temperature would drop from 15°C to -63°C. So it would be pretty cold. The actual temperature in the poles would depend on how much energy transport is there from the equator to the poles. A model would be needed to figure that out too.

Eventually, it will happen what is usually thought to have allowed Earth to escape from ice ages: As the land is covered in ice, it can't take up CO$^2$ from the atmosphere (normally happening due to the weathering of silicate rocks), but the volcanoes keep putting CO$^2$ into the atmosphere. Therefore, at some point the amount of atmospheric CO$^2$ is so large that the greenhouse effect can rise the temperature enough to melt the ice sheets and go back to what we call "normal".

This is already too long so I'll refrain to address that bonus question. However, I'll say that the orbital configuration to have permanent summer in either hemisphere would be quite difficult to attain. You would need the Precession period of the Earth to be (and remain) exactly one year long.


Where can I get historic hourly precipitation data for Italy?

The US NCDC has this link to surface hourly global data which I was indeed able to find Napoli on.

It appears, based upon this page describing the World Data Center For Meteorology, that there may be restrictions on using the data commercially outside of the United States.


Is there a database of the geologic/stratigraphic units of France?

The best I have been able to turn up is the paid BD-logs service, which provides standardised lithology for borehole data. Open Geospatial Consortium data all appears to be listed on the Geoservices page, and does not appear to include a lithological database/lexicon. The French Geological Reference Platform does not appear to include a standalone database. The BRGM's list of resources also does not appear to provide pointers to any relevant information. Given that the FRGM is in active development, it seems plausible that this is not in fact a dataset that currently exists.


How do mountain springs get their water?

Ultimately, it comes from precipitation.  Ordinarily we think of rain as coming from low-level clouds, but Putkonen[1] has compiled rainfall data in the Himalayas showing significant rains up to several thousand meters altitude, covering the range where practically everyone lives.  It is this precipitation that fills the underground tables mentioned by Jean-Marie Prival in a comment to the question.

Such a source is subject to the effects of climate change, which accordingly has led to significant environmental issues.  See Ref [2].

References:

1.
Jaakko K. Putkonen, "Continuous Snow and Rain Data at 500 to 4400 m Altitude near Annapurna, Nepal, 1999–2001", Arctic, Antarctic, and Alpine Research, 36:2, 244-248 (2004)

2.
Sandeep Tambe, Ghanashyam Kharel, ML Arrawatia, Himanshu Kulkarni, Kaustubh Mahamuni, Anil K Ganeriwala,
"Reviving dying springs: climate change adaptation experiments from the Sikkim Himalaya",
Mountain Research and Development 32 (1), 62-72 (2012)


'Peak water' in the Ogallala Aquifer, USA?

It is definitely possible to completely drain an aquifer.  However, as the potentiometric surface (water level) in the aquifer drops, extraction of water becomes less economical, but the perceived value of the water increases. It is possible to apply "unconventional" drilling techniques like directional drilling and fracking to extract groundwater. You could potentially get philosophical and argue that there is a point where the aquifer no longer meets the definition of an aquifer.

Your question is really a matter of scale.  The USGS Principal aquifer map depicts the Ogallala aquifer as a complete and continuous hydrostratigraphic unit because that map is a national-scale map.  It would be more appropriate to call it the Ogallala aquifer system, to remove implications that it is one continuous, well-connected aquifer system that runs across several states.  It is much more likely that this aquifer is a group of hydrostratigraphic units separated by faults, confining units, and lateral discontinuities.  Because of this horizontal heterogeneity and because pumping influence such as cones of depression is generally localized, you could potentially completely deplete some portion of the aquifer system while leaving other portions with some water.

In terms of the water budget, as you have shown in the above USGS figure, discharge is already outpacing recharge. In their Public Information Circular 18, the Kansas Geological Survey projects that some parts of the aquifer system will be depleted within as soon as 25 years, while other regions have a life expectancy of between 50 and 200 years. In an interview with the Lubbock Avalanche-Journal, the Center for Geospatial Technology at Texas Tech said that some regions of the aquifer in Texas only have 15 years of water left.

As water is removed from an aquifer, the pressure that water exerts to help hold up the aquifer skeleton is reduced.  The reduction in water pressure can cause deformation in the aquifer. Some component of this deformation is recoverable (elastic). However, if the stresses on the aquifer exceed that of what the dewatered material can handle, then the dewatered aquifer/confining layers could undergo permanent compaction, leading to a decreased ability of the aquifer to store water. See USGS Circular 1182 for more information on these concepts.

While the technology exists to implement artificial recharge, either via injection well or infiltration ponds/galleries, this technique requires adequate geochemical conditions and an appropriate recharge source. Once an aquifer system is stressed to the point of compaction, its storage is permanently decreases, reducing its value as a candidate for artificial recharge.  For more information on artificial recharge, see the USGS website.


Has there ever been a case where we have found what appears to be a prehistoric fossil but have no way of dating it?

The short answer is no, because we always have some constraint of how old something is.  Sometimes we have fossils with large date error bars, and often we do not know for how long that species existed. A large date range constraint in some cases, like archeology, might not be useful. If the specimen is taken without noting the location it was taken from, then we have no context to date it, which is a big reason not to plunder paleontological sites.

For dating a fossil, the context of the rock layer, other fossils, cross-cutting units, and location is key.  Geologists must use a combination of absolute and relative age dating techniques.  Geologists examine the rock layer from which the fossil was found and compare that to other rock layers that stratigraphically correlate to it.  They use basic relative dating approaches, including:

Principle of Superposition: older layers on bottom, younger layers on top
Principle of Cross Cutting Relationships: if a feature (like igneous intrusions and faults) cuts through a layer, then that feature is younger than the layer
Principle of Original Horizontality: Layers are deposited in a horizontal fashion
Principle of Lateral Continuity: Layers are general deposited in a laterally continuous manner until they pinch out; if you see a canyon and similar layer on either side, you can assume it was previously continuous and the canyon is younger.
Principle of Faunal Succession: The presence or absence groups of fossils can be used to hone in on the time period

There are a wide variety of absolute dating techniques, each with its own time and medium constraints. Radiometric dating, fission track dating, and paleomagnetic approaches are typically restricted to igneous rocks. For radiometric dating, only a small quantity of isotopes are needed for a measurable date. Igneous rocks contain usable quantities of minerals like zircon that are good at holding atoms of uranium and other elements useful in for the absolute age-dating technique. Geologists use absolute dates of rocks that can be dated in combination with relative dating techniques to constrain the age of a rock layer that cannot be dated with absolute techniques.

Fossil morphology must also be considered to determine if you are really looking at a new species or just a special case of a previously identified species. Sometimes, evolutionary approaches can be applied to help place the specimen into a timeline.

Figuring out the temporal extent of a species takes more time and multiple discoveries of samples of that species to better constrain that extent.

A combination of approaches and techniques can help paleontologists be detectives in determining the age of specimen. Like other sciences, geology is social in the sense that it relies on the culmination of the work of many, with multiple lines of complementary pieces of information, to come to a conclusive age.

Here are some great articles related to your question:

DiMaggio, E. and Tripathy-Lang, A., 2019, How Do Scientists Date Fossils?: Smithsonian Magazine, online: https://www.smithsonianmag.com/smithsonian-institution/how-do-scientists-date-fossils-180972391/
Peppe, D. J. and Deino, A. L., 2013, Dating Rocks and Fossils Using Geologic Methods: Nature Education Knowledge vol. 4, no. 10:1, online: https://www.nature.com/scitable/knowledge/library/dating-rocks-and-fossils-using-geologic-methods-107924044/

Here is an example of an "undatable" fossil, where the age could "only" be constrained by 2 million years:

Yong, E., 2015, Why Don't We Know the Age of the New Ancient Human?: The Atlantic, online: https://www.theatlantic.com/science/archive/2015/09/why-dont-we-know-the-age-of-the-new-human-ancestor-homo-naledi/405148/


Which is worse, plastic or styrofoam cups?

I suppose the answer depends on total lifecycle emissions as well as landfill environmental cost.
For plastic I assume PP or PETE.
For styrofoam production is based on polystyrene so some styrene emissions.

For lifecycle costs, emissions for manufacturing as well as energy (coal or gas power plant) need to be considered. Also are either recycled and in what proportion and does that impact lifestyle costs. Not an easy question, or one I can quantify. For simplicity l would look at two questions- production emissions of the actual cup and or feedstocks and recyclability of each cup.  According to this link styrofoam is not recyclable so I would guess plastic is not as bad.
https://sciencing.com/styrofoam-vs-plastic-cups-12400119.html
Here it says polystyrene is usually not recyclable locally. https://science.howstuffworks.com/environmental/green-science/polystyrene-recycling.htm
Here is a different perspective whose author suggests styrofoam lifecycle cost could be lower compared to some other options:
https://daily.jstor.org/is-the-30-year-long-styrofoam-war-nearing-its-end/

Not exactly an answer but at least a start


First, great question, though answers are likely to be non specific and speculative.

  As far as I understand, we are currently living in the Holocene, an
  interglacial period of the Quaternary glaciation, i.e. the current ice
  age that has so far lasted 2.6 million years. The Holocene began about
  12,000 years ago. While humans emerged about 200,000 years ago, human
  civilization is almost entirely coterminous with the Holocene.

As others have said, defining our current period as the Holocene is iffy.   Human influence is pretty huge, and perhaps, even as many as 6,000-7,000 years ago the growth of the agricultural revolution, some farm animal domestication and early, though much smaller, deforestation may have played a role in climate, at least, I remember reading that, though a quick google didn't provide a good source, but I've read that.   It's probably not consensus though, just some people's opinion.

  (A) Are there any generally accepted estimates for how long the
  Holocene will last?

So, how long?   There's 2 very different answers to this.

First one, if we take out the human effect, or, lets say, in the relatively near future we "fix" our CO2 and other human effects on the planet and return the Earth mostly to how it was.   Then the answer is kind of simple, we just Look at past warm periods and make an estimate from those.

Without human activity the Holocene would very likely be just another inter-glacial warm period between ice ages in the continuation of the Quaternary with a similar length of time.  See chart:, If the average length of inter-glacial warm period is about about 20,000 to 40,000 years we can just subtract 11,000 from that and reach a rough estimate.

Or, if you want more accuracy, you can look closely at the 3 orbital cycles and calculate based on that - but I'm not going to do that as it would get more complicated.  More on that here.

It's also likely that there would be a cooling period within that time-frame.  We can see cooling, like the little ice age, without it being an actual ice age.

  When will glaciation resume? Has global warming delayed return to
  global cooling?

  (B) Is anthropogenic global warming delaying the return to glaciation?

First, it's worth pointing out that returning to global cooling and a return to glaciation aren't entirely the same thing.   If, lets say, we continue our CO2 footprint/production and reach 450 PPM before we cut back enough to level off for a few decades, then, cut back enough to see the oceans gradually take in CO2 and reduce the levels in the air, we could see a gradual global cooling within 100 years or so - maybe, provided the higher ocean temperatures and Albedo drop due to loss of ice cover didn't created a new equilibrium.   But in general, the earth can go through cooling periods without glaciation, so those 2 questions are similar but not entirely the same.

But in general, calculating glaciation with the human factor, it's a much harder question, especially since we can't see the future and how high CO2 levels will get.

Modern ice ages are defined as an advancing glaciation across a significant range of the Northern land, which, as pointed out above, coincides well with Milankovich cycles, but to actually have that happen, you need a few things in place.   Milankovich cycles don't cause ice ages all by themselves, cause they were there during non ice ages too.

The modern ice age cycle only started about 2.6 million years ago and it is thought to have been brought about by the formation of Isthmus of Panama about 5 million years ago, which separated a current between the Atlantic and Pacific Oceans which helped the arctic ocean cool and freeze over.  Shortly after that Isthmus formed, the Earth began to cool.   See here (chart from Milankovich link above).

Modern ice ages also coincide with falling CO2 levels, and while the CO2 drop follows the temperature drop, there's a reason for that.  Colder oceans hold more CO2, so the Atmospheric CO2 drops when temperature drops.  This serves as a feedback loop where cooling leads to more cooling and that's part of why ice ages are as big as they are.   Albedo is another feedback loop, so the trigger to get an ice age started is actually pretty small.   The Orbital cycles of the Earth are thought to only contribute about 1 degree of cooling in and of themselves and the other 9 or so degrees of global cooling between peak ice age and average Holocene is thought to be caused by these feedback mechanisms, primarily albedo and drops in atmospheric CO2.

So, there's 2 questions to ask as to whether man made global warming will prevent the next ice age and perhaps future ice ages.   We know that the Milankovich cycles will continue, but will CO2 be low enough for the cycle to lead to glaciation, and, how fast will CO2 levels drop, so, over the next 10,000 - 30,000 years.    Nobody knows the answer to those questions.

Looking at the last 800,000 years or so, based on ice-core samples, warm periods between ice ages you usually have about 260-280 PPM and peak ice age periods, about 180-200 PPM CO2 with the ranges in between, mostly during transitional periods.  When these changes occur, most of the CO2 is believed to be absorbed into or released from the oceans, though I see no reason why a smaller portion of the change couldn't be driven by changes in living bio-mass corresponding to the changes in temperature, ocean size and grow-able land area.

By burning fossil fuels, we've added carbon that was effectively removed from the Carbon cycle. For a rough calculation for how much, every year we add a bit over 30 billion tons of CO2 by burning fossil fuels every year.

The Atmosphere, at 270 PPM with a mass of the Atmosphere, about 5.148 x 1018 KG is about 2,320 billion tons.   Since the industrial revolution, CO2 PPM has increased to about 400 PPM, which is an increase of about 1,030 billion tons (atmosphere only) with roughly about 400 billion tons (rough estimate), having been absorbed into the oceans.

Oceans are estimated to store about 50 times the CO2 than the Atmosphere, Source, so assuming that's accurate, Oceans currently store over 110,000 billion tons of CO2 and since the industrial revolution, we've added (ballpark) 1,400 billion tons from burning fossil fuels - about a 1.2 - 1.3% increase to the total CO2 in the Oceans, Air and Land-biosphere.   That's the crux of the question, what effect will that have.

Over enough time, like, 10,000-30,000 years when the next ice age might be due, the oceans could absorb most of the atmospheric CO2 and the effects could be fairly small.   But as the Earth warms and Oceans warm and warming oceans increases the Atmospheric CO2 cause oceanic absorption drops.  With warmer oceans there will be a new equilibrium and with that in mind, it's entirely possible that the new atmospheric CO2 equilibrium, if left to it's own devices, might already be sufficient to prevent ice ages for a long time, perhaps a few hundred thousand years.

Predicting atmospheric CO2 levels 10,000 to 30,000 years from now, for all practical purposes, impossible, and that's what we'd need to know to estimate if we've stopped the next ice age or not.   What we have done is increased the amount of CO2 in the biosphere of earth by about 1.2–1.3% and since we continue to burn fossil fuels, we're likely to have created an increase of 2% before alternatives are in place, perhaps a bit more than that.

All of this, however, is probably irrelevant, cause we have some ability to trap CO2.   It's not easy, but we can do it and if, as our technology improves and we begin a gradual CO2 trapping program, we could re-start the next ice age in 10,000 years or so, assuming that's what we want to do.   Now, I don't mean to make light of the CO2 problem cause we appear to be facing very big and real issues over the next 20-50-100 years and that's much harder to avoid at this point, but over 10,000 years, we could probably fix our CO2 situation and bring the Earth back into the ice age cycle, or, we could use CO2 to avoid future ice ages if that's preferred.  Collecting and trapping 1–2 trillion tons of fossil fuel generated CO2 isn't easy and we don't have nearly the technology to do that today, but over 10,000 years I feel pretty confident that we could be able to do it, provided we keep progressing technologically.


Future geology professor wants to know quick fixes to get me through unstimulating period

I'd suggest to get out and do some mapping. Get a map, look for local outcrops and mark them on your map. Try to find the same type of rocks or unit in more than one location and try to connect them. Compare it with published maps and see if it makes sense. Then start to think about the reasons why the units are located as they are and read a bit about tectonics. Your chemical interest is useful to define the rocks you find (e.g. use acid to recognize carbonates) and your biological interest is useful if you are fortunate enough to live in an area where you can find fossil bearing rocks to help you with the dating. The experiences you make whiles learning the trade can suggest what the local work market looks like. Learn GIS and mapping.

Geology is a great way to combine theoretical studies with fieldwork and use some excess energy. Let your interests define what branch of geology you would like to focus on.

If you are looking for professional projects, I'd contact local engineering companies that work with infrastructure or similar and check if the need extra crew for fieldwork. There are sometimes casual workers needed for geophysical surveying or sampling.

Depending on where you live, groundwater could be another option, contact local drilling companies, learn how to handle a rig and learn some hydro-geology. With a detailed geological map of an area, groundwater modellers can make better decisions - maybe even paying something for the data.


Does rain itself affect barometric pressure?

Under a hydrostatic assumption the basic equation is p=/rho R T. So under this easy equation the pressure depends to the air density and the air temperature. As you may know diabatic processes during rain yield to a decreasing temperature. but the magnitude in change of pressure against the synoptic scale forcing is low.

Please be aware of mixing stuff together answering this questions. The question was not to answer how precipitation is forming. It was just the question about the rain influencing the pressure.


This is the centroid moment tensor published by the USGS as of 01/10/18 (it will likely be updated in the future). As you can see this was an almost pure strike-slip mechanism on a near vertical plane.

Tsunamis are generated when the ocean floor is displaced upwards by an earthquake, displacing the water above it in the same pattern. This displaced water then spread out laterally to form the tsunami. Thrust faults tend to produce large seafloor uplifts and so most (maybe all?) tsunamis are associated with thrust faulting earthquakes.

There was no tsunami in this case because a strike slip fault like this does not produce a significant uplift of the seafloor. Instead the seafloor slides past each other.

With regard to the second part of the question; yes there have been tsunamis in the Caribbean before. This website provides a good list of known ones.


Should one extract wavelet from seismic or well log for the generation of synthetic traces?

Seismic, but...

There are lots of ways of estimating wavelets. None of them rely on well logs alone, because they don't contain any information about the wavelet. Some methods are purely statistical, some use the seismic data, and some of them use seismic and well logs.

Background

I recommend reading what you can about wavelet extraction. Especially these (see links to many of these here):

Brown, A (2001). Calibrate yourself to your data! A vital first step in interpretation. Geophysical Prospecting 49, p 729–733.
Roden, R and H Sepulveda (1999). The significance of phase to the interpreter: practical guidelines for phase analysis. The Leading Edge 18, July 1999, p 774–777.
Simm, R and R White (2002), Tutorial: Phase, polarity and the interpreter's wavelet. First Break 20 (5), p 277–281.
White R, and R Simm (2003). Tutorial: Good practice in well ties. First Break 21 (10), p 75–83.

Workflow

My approach, for what it's worth, is as follows:

Establish that your seismic data are zero phase. See this wiki article and this tutorial.
Tie your wells with a purely statistical zero-phase wavelet until you know better. A Ricker is fine for most impulsive data. Don't bother with autocorrelation. Don't bother with mixed-phase. Once you've found the best one, don't change it from well to well.
Take your best well ties (maybe the best 10 or 20 percent), and check them.
Try extracting zero-phase wavelets from your best data, preferably near angle stack, and unfiltered (e.g. by fk, which processors love) — you don't want any spectral shaping nonsense. Only use the zone of interest, but at least about 1000 ms of data. Avoid the near surface.
Average all the wavelets you got and tie all your wells with this wavelet. The ties should improve in most cases.

Note: Step 4 usually involves estimating the wavelet from the seismic data, using the reflectivity from the wells. It's basically the reverse of making a synthetic: seismic / reflectivity = wavelet, where / denotes deconvolution.

Caveat interpretor

I would complete the workflow for each seismic survey (e.g. a 3D, or all lines in a 2D). Your goal is to use a single wavelet for each survey. This goal reflects the assumptions in this workflow:

The reflectivity is random.
The wavelet is zero-phase or minimum-phase.
The wavelet is stationary (invariant in space and time).

None of these assumptions hold (Ziolkowski, 1991; Why don’t we measure seismic signatures? Geophysics 56, 190–201; see also this thesis). This is what makes it fun! Your job is to cope with this without breaking the laws of physics or what we know about geology.


are laccolith, lobolith, dikes and sills formed of porphyritic texture?

Laccoliths, lopoliths, dikes and sills are all characteristic modes of occurrence of hypabyssal rocks, generally small in scale compared to most magma chambers. They are magmas which have cooled in a near-surface environment. None of these terms necessarily implies a particular petrologic texture. So, for example a dike or sill may be aphanitic, porphyritic, aplitic, pegmatitic or even glassy obsidian - and other less common textures. Nevertheless, many hypabyssal rocks are porphyritic. All this means is that the magma crystallized in two stages. The first stage was deeper and slower cooling, allowing some crystals to grow, sometimes to much larger size than the rest of the crystalline matrix. The second stage is when the magma is intruded at shallow depth, resulting in much more rapid crystallization of the remaining melt. Hence the porphyritic texture of large crystalls within a fine-grained matrix.


What is this geographical feature? (as seen in maps)

The dark color of the water masses make me think they are peatlands in tundra.

Peatland is a terrestrial wetland ecosystem in which the production of
organic matter exceeds its decomposition and a net accumulation of
peat results.
The largest known concentrations of peatland are found in Canada and
Alaska, Northern Europe and Western Siberia, Southeast Asia, and parts
of the Amazon basin, where more than 10% of the land area is covered
with peatlands.

Source: peatlands.org


Why does Australia have extensive uranium ore deposits?

An aptly named webpage from GeoScience Australia: Why Australia has so much uranium provides some insight as to some of the reasons behind the Australian continental relative enrichment in uranium.

Consider the following map from the GeoScience webpage:

One link that is stated on the website is that in regards to major uranium deposits"

  observations support the conclusion that the large number of uranium deposits and prospects across Australia reflects the extensive emplacement of uranium-enriched felsic rocks in three main periods of igneous activity. While some uranium deposits appear to have formed during these widespread thermal events, most formed from uranium-enriched source rocks by subsequent low-temperature processes.

These 3 main periods occur:

Late Archaean (2.69-2.65 Ga)
the Palaeo-Mesoproterozoic. (~1.9-1.5 Ga)
and a bit younger in eastern deposits, the Silurian to the Permian (0.43-0.25 Ga)

The last point in bold above is elaborated further by the website, that uranium mineralisation being younger than the related intrusive igneous rocks.  Particularly evidenced by deposits found in calcrete, sandstone and unconformities:

  appear to have formed as a result of uranium mobilisation from older uranium-enriched source rocks under low-temperature oxidising conditions, and precipitation by redox reactions. The high-grade deposits are likely to reflect relatively more efficient oxidation-reduction systems.


Where on Earth is the highest none polar magnetic fields?

In other words where might be a natural place on Earth that would over power a compass and then some

Just about anywhere where the rocks are rich in iron. This would occur near iron ore, basalt, gabbro, and similar iron-rich rocks. You really don't need a lot of magnetite in the rock for this to move the compass needle. You don't even need magnetite - chromite or pyrrhotite rich rocks may be enough to move the compass needle off.

This is a common problem when navigating only using a compass in basalt rich areas. A good historical example is that of Tasmania. You can read about it the following article:

Magnetic rocks—their effect on compass use and navigation in Tasmania

As for a map, you're probably looking for a magnetic anomaly map.

Here's an attempt to make a global , or this one from USGS, or this one being offered for sale.


What is the physical meaning of second moment of wind velocity?

The (statistical) variation is not the same as the gradient. The gradient is a measure how things change from here to a nearby point, or from now to a point in the near future. The variation, on the other hand, just says how often wind speeds of different magnitude happen.

For example: If the wind were to blow at exactly 30 km/h all the time, then the average wind velocity is going to be 30 km/h and the variation is zero. Conversely, if the average is 30 km/h and the variation is large, then the wind will blow at different speeds, typically quite different than 30 km/h, but so that the average is 30 km/h.

What's the importance in the context you're considering? If the variation were small, it would be fairly easy to design wind generators because they would only have to accommodate exactly one wind speed, which happens to be blowing all the time. On the other hand, if the variation is large, then you have to design wind generators so that they can produce electricity when there is little wind, when there is the average wind speed, and also when there is a storm. It's a bit like designing aircraft for (slow) take-off and (fast) cruise speeds -- it's complicated, as you can see with all of the flaps and levers moving on the wings of planes between start and cruise phase.


Digitalizing precipitation data from the image of weather map

You can convert the image to NetCDF data using gdal_translate. The command line looks something like:

gdal_translate -ot Int16 -of netCDF jpeg_filename nc_filename

You can use ncl example: click here


Why does part of the P-wave convert into a S-wave with an increase of incidence angle?

The way I imagine this phenomenon is illustrated in the picture below. I have to warn you that it lacks scientific accuracy and is just a simple way to imagine the effects we observe on a reflective boundary. However, it can be useful as a simple model you can easily imagine.
In the upper picture you can see an illustration of a reflection event at a horizontal boundary.
The lower picture illustrates how the vector of particle motion in a down-going P-wave is 'decomposed' into two vectors. First component is a vector of particle motion in an up-going S-wave, the second corresponds to particle motion in an up-going P-wave.

Once again, this is not how the rays exactly behave in a reflection event. Here we do not take into account transmitted waves and lots of other factors. Nevertheless, sometimes you can use this 'approximation' because it satisfies two conditions:

At normal incidence, there is no mode conversion (shear wave does not appear)
As the incident angle increases, the amount of shear-wave energy increases too.

These effects are also observed in real life.
Exact description of a reflection event on a plane boundary, as kwinkunks has  mentioned above, is given by Zoeppritz equations. They take into account all details and are widely-used. No doubt, they are much more difficult (but physically correct!) than a simple sketch I suggest.

.


Why do rainbows appear to have a fixed structure?

In short, this is because the location of a rainbow is not dependent on water droplets. The location is only dependent on the location of the Sun and of your eyes. The visibility of the rainbow is what depends on the presence of condensed water.

As each drop passes through a location that corresponds to that of the rainbow your eye will see the reflected photons originating at the Sun. Before and after the rainbow, that individual drop is not in a location that allows you to see these reflected photons. The rainbow appears stationary because it is (as long as you aren't moving) and droplets are falling through it often enough that it always appears visible.


Why aren't there ultra acid igneous rocks?

Warning: not an igneous petrologist here, I'm more interested at what happens to magmas once they reach the surface than all the processes they might have encountered along the way...
That being said, I think it has to do with the source of magmas, that is the mantle, which is itself mafic. Hence partial melting of the mantle generates mafic magmas. These magmas can then differentiate into more "evolved" (i.e. intermediate or felsic) ones. But there are limitations to these differentiation processes. With fractional crystallization you make mafic minerals, pumping Mg and Fe from the melt and leaving it silica-enriched, but you will never reach a 100 % silica melt (after all mafic minerals are still silicates, they need some Si in their structure). Same with crustal assimilation: the continental crust is only andesitic (intermediate) on average (Rudnick 1995), and even with assimilation of more felsic (i.e. granitic) portions you would never reach a 100 % silica melt. The starting material is too mafic.

On a more "philosophical" note, I would add that despite the absence of the term "ultrafelsic" in the literature, one could still consider some rocks as being ultrafelsic. If you look at the chemical classification of volcanic rocks (Le Maître et al. 2002), the four fields are separated like this (silica content in wt%):

Ultramafic: SiO$_2$ < 45
Mafic: 45 < SiO$_2$ < 52
Intermediate: 52 < SiO$_2$ < 63
Felsic: SiO$_2$ > 63

So everything above 63 wt% SiO$_2$ is just "felsic". But there are some rhyolites with more than 76 wt% SiO$_2$ (some of Mono Domes for instance, see Table 2 in Bray et al. 2017)! So there is no distinction between a low-silica dacite and a high-silica rhyolite: they all are just "felsic". That doesn't mean they are not different, just that we never bothered making a fifth filed. But those fields are just arbitrary, we could have split the silica spectrum into twelve fields, or just two.


How do I estimate the mass of a deciduous tree's leaves?

David LeBauer is correct in saying that there are 'allometric equations' to estimate the leaf biomass, but they only refer to small experimental plots in such places as Hawaii, Japan, Singapore and Malaysia. The number of species involved is a few dozen at most. As 'N9ZN' points out, trying to develop generalizations would be a titanic task, and essentially impossible without a vast amount of experimental work. There are about 50,000 tree species in the tropics alone, each with its own calibration curve, not to mention ecologic, microclimatic and nutrient constraints upon leaf development.

I would suggest that, instead of trying to develop a deterministic result, since leaf biomass is approximately related to potential evapotranspiration and water availability/constraints, it would be easier to estimate average water usage by stem dendrometry, crunch the numbers for ET0 based upon climatic data, and then develop a biomass conversion efficiency. As far as I know, this hasn't yet been done, at least on anything other than a very small scale - but theoretically it should be doable.


Last ice age: did glaciers move South or move downhill?

Did glaciers move South or move downhill?

You are posing this as an either-or question. The answer is "Yes."
The highest points above sea level in Manitoba, Minnesota, Ontario, Michigan, Wisconsin, Iowa, and Illinois are respectively 832 meters, 701 meters, 693 meters, 603 meters, 595 meters, 509 meters, and 376 meters. Central Canada and the United State's upper midwest are very flat.
Even the eastern parts of the US and Canada are relatively flat compared to the huge ~4000 meter thick ice dome centered roughly on Hudson Bay. Every direction was downhill from the peak of this ice dome. The ice flowed to the west to meet ice streams from the Rocky Mountains (and then turn north or south), to the north toward the Arctic Ocean, to the east toward the Atlantic Ocean, and to the south to meet warmer temperatures. The ice at the southern edges was much thinner, but it still was a downhill flow.


Were Carboniferous plants more efficient sequestering $\ce{CO2}$ than present plants?

Probably not.
The biological pathways to make lignin is the same in all plants so there is no reasons to believe they would be better. If anything modern trees as a whole may be better since they survive in  larger range of environments and very dense wooded trees exist. In addition without defenses against modern wood decomposers Carboniferous plants may have a hard time surviving in the modern world.


Source of Dresser Formation 3.5 Ga dating

From Australian Government- Geoscience AustraliaAustralian Stratigraphic Units Database:

Panorama Formation:  Paleoarchean min age: 3427 MA Age method: isotopic, U/Pb-Pb/Pb ion probe

Dresser Formation: Min Age: Ma: 3477 Age method: inferred, overlying unit

McPhee Formation:  Min Age: 3477 Age method: isotopic, U/Pb-Pb/Pb ion probe


How do the swirls and veins in marble form in detail?

What you see in marble are not veins (for example in the picture of yours). By the term vein in geology we mean a magmatic intrusion in the rock in the form of vein. Can a marble have magma real veins? Yes. The process is explained here: https://en.wikipedia.org/wiki/Intrusive_rock
The 'veins' you are referring to are coming from the different beds of the rock formation. Beds form by the deposition of layers of sediment on top of each other and they might have variations in mineral composition.
As BillOer mentioned already, marble is a metamorphic rock formed from limestone. Can I have different type of 'veins' and swirls in the metamorphosed limestone in comparison with the initial limestone? YES. Why? Because during the metamorphic phase, pressure and heat is applied to the rock. So, we might have a partial melt and re - crystallization, a pressure slide forming swirls and new 'veins'.


How much silicon is in the Earth's core, and how did it get there?

The only way presently is to simulate the conditions in the core, as has been performed in the article Oxygen and silicon contents of Earth's core from high pressure metal–silicate
partitioning experiments (Ricolleau et al. 2011), whose results indicate that

that the oxygen metal–silicate partition coefficient increases
with increasing oxygen fugacity, temperature and pressure, whereas the silicon metal-silicate partition coefficient increases with decreasing oxygen fugacity, increasing temperature and pressure.

The model also revealing that the approximate concentration of silicon in the core (outer core) is up to 11 wt%, depending on what model of core formation was used in the simulation.  These results

in the core could satisfies the seismologically observed range of outer core
density deficits.

In terms of how long the silicon is believed to have been in the core, in the article Silicon in the Earth’s core (Georg et al. 2007), similarities with the silicon content with the Moon led to their conclusion that

$Si$ was already incorporated as a light element in the Earth’s core before the Moon formed.


How do you determine the age of >60 year old water?

According to this pdf: Physikalische Grundlagen der Klimaarchive Eis und Grundwasser (mostly German - some English) all methods to determine the age of groundwater bodies older than ~60 years are radiometric:

39Ar: 30 yr - 2000 yr
14C: 1,000 yr - 30,000 yr
36Cl: 100,000 yr - 1,000,000 yr
81Kr: 100,000 yr - 1,000,000 yr
40Ar: 100,000 yr - >10,000,000 yr
4He: 10 yr - >10,000,000 yr

Another source (german only) also mentions 32Si with a similar range as 39Ar.


Which method is used to calculate tonnes carbon from tonnes CO$_2$ equivalents of GHGs?

OK it depends a lot on what exactly you mean. There is a known problem with people talking about "carbon" / "atmospheric carbon" / "Carbon Dioxide" and using the terms imprecisely - so there is often a confusion about which exact chemical species is being discussed.

Tonnes of C to CO2 is (as you correctly stated) a conversion based on molecular mass, but this doesn't really help us if we're talking about something like methane which contains carbon, but has a dramatically different effect in terms of global warming. It is even more complicated when you take into account the change in lifespan of these different species (methane degrades in the atmosphere much more quickly than CO2 for example)

The usual method to deal with this is to calculate Global Warming Potential (GWP). This compares the actual radiative forcing over time (the change in the earth's energy balance) to a fixed time horizon (usually 100 years) when compared with CO2. We can therefore compare the actual equivalent effects of releasing a number of different gasses in units of CO2 equivalent.

The details of how it's calculated and why the time horizons are where they are is in the IPCC AR5 WG1 CH8 technical supplement (8.SM.11.1 Equations for the Global Warming Potential)

Hope this helps


Your first question, regarding salt pollution requires a back-of-an-envelope calculation. At present, about 4% of the global population relies, either wholly or in part, on desalinated water. Because this is energy intensive, it is also expensive, so such water users are parsimonious, using about 1% of the global domestic water supply. But let us, for the sake of argument, assume that the desalinated option really takes off at some time in the future, perhaps by means of less energy intensive 'forward osmosis'. We will assume that 10% of the current population (7.4 billion people) may eventually use desalinated water, yielding a daily delivery of bitterns with 2.45 x 10^^9 tonnes of salt. Compare this to the 1,5 x 10^^17 tonnes of salt already in the ocean - the salt return would be 0.0000016% of what is already in the sea. Moreover, even this trivial amount would be diluted by the hydrological cycle, because the water that is drunk, used for washing, etc, ultimately returns to the sea.

But you ask whether the local concentrated saline return would be harmful to the environment? Consider Adelaide, in South Australia, which boasts the largest desalination plant in the southern hemisphere. Very detailed studies, by both computer modelling and direct observation, show that the dispersion of the saline plume reaches concentrations undetectable against the background salinity, within a few hundred metres of the outflow. It certainly hasn't impacted the local marine ecology at all - and the South Australians are very particular about environmental issues!

Again, consider the greatest concentration of desalination plants in the world, in the Arabian Gulf. This shallow-water (<50 metres) Gulf has high natural rates of evaporation, which raises the salinity from the normal 3.6% to about 4.1%. This change is orders of magnitude more than can be attributed to the salinity change from all the desalination plants combined. The ecology and biodiversity of the Gulf is still rich, and not at all affected by local bitterns effluent. Climate change will intensify evaporation, which is much more of a worry than 'desal' plants.

As to your second question about changing the climate and increasing rainfall by pumping bitterns into the desert, there is a massive problem with that. As the salinity increases by evaporation, the vapour pressure at the lake surface decreases, which suppresses further evaporation. Since we would be dealing with hyper-saline brines to start with, we would rapidly approach an equilibrium in which the massively decreased evaporation would equal the natural deliquescence of the salt. In fact, evaporation would win, but only slightly. The loss of moisture to the atmosphere would be barely noticeable, and not sufficient to terra-form the down-wind area.

I suggest that the impacts of global warming will massively eclipse any trivial changes brought about by evaporation basins. If you don't believe me, I suggest you get some hydrologic and geochemical textbooks, and do some mass-balance calculations of your own.


Available Matlab code to design Seismic Colored Inversion Operator?

Here is a link to a colored inversion operator design code written and provided by Peter Zahuczki.

This code requires that you provide a P-impedance log amplitude spectrum; he uses the open-source interpretation software OpendTect to compute this spectrum.

Peter has a easy to follow tutorial on how to use his code with OpendTect. Good luck!


What are the basic rules of how light and seasons affect landscape and objects lighting?

I suspect that the answers you seek lie as much in computer graphics and human perception as they do in physics or earth science - for example, colours on a cloudy day won't actually be significantly less saturated than on a sunny one - it's still white light to most intents and purposes - but we may perceive them that way due to the differences in contrast, illuminance, and colour.

There are three components to natural light :

You can calculate the angle of the sun according to time of year, time of day, and latitude. From this angle, and the altitude of your viewpoint, you can estimate the colour of the direct sunlight. The more air it has to travel through, the lower the colour temperature and the intensity.

Then you need to consider the blue sky. This will be lighter at low altitude and darker at high. You'll need to do something about the sunwards sky not being blue at low sun angles. The blue sky casts light on things, but this is mostly only evident by shadows appearing a bit bluer than their surrounds.

Then you need to consider cloud cover. For a flight sim this is complicated by the fact that it may be above or below the camera, or you might be in it. One approach might be to treat clouds as large diffusers that act on the light from the sun and from the blue sky. Whether this is feasible is beyond my ken, and definitely lies in the realm of computer graphics, not earth science.


How was the Marinoan Glaciation triggered?

Several articles suggest that the mechanisms involved with the weathering and/or the breakup of supercontinents as being a mechanism for this kind of glaciation, in the timeframe pertinent to your question, Rodinia.

According to the article Precambrian supercontinents, glaciations, atmospheric oxygenation, metazoan evolution and an impact that may have changed the second half of Earth history (Young, 2013), a suggested mechanism of the onset of glaciation is the formation of the supercontinent, specifically, the author postulates:

  Enhanced weathering on the orogenically and thermally buoyed supercontinents would have stripped $CO_2$ from the atmosphere, initiating a cooling trend that resulted in continental glaciation.

The Polarisbreen Formation is touted in the article The Marinoan glaciation (Neoproterozoic) in
northeast Svalbard (Halverson et al. 2004) suggests that weathering as being one of the main factors for the sustained glaciation.

An alternative hypothesis is proposed in the article From Volcanic Winter to Snowball Earth: An Alternative Explanation for Neoproterozoic Biosphere Stress (Stern et al. 2008), where the authors suggest that increased global volcanism from the breakup of the supercontinent.


Does the feel of temperature change, when you're in two different places

Opinions are often very subjective and can't make accurate assessments, especially in matters like this where the two things being compared are vey much alike. The only objective way of doing it is to have accurate temperature and humidity readings over a period of several years for both places. Someone has probably already done that, but I don't know where the best place would be to see their results. Being a relatively small island, Guam should have a marine climate, which is less extreme than continental climates. We have a marine climate here in Britain, and though we often complain about the weather it is less extreme than weather in Europe. A marine climate gives us cooler summers and milder winters, as the temperature is moderated by the sea, which also gives us a damp climate. Guam is nearer the equator than Maryland and is rainforest country, so I would expect it to be fairly humid but not so extreme and variable as Maryland.


What is the mass of our planet's atmosphere, hydrosphere, and cryosphere combined?

Pretty darn accurate. To first order, the atmosphere's mass is the average atmospheric pressure at the Earth's surface times the total surface area divided by the acceleration due to Earth's gravity. Or if you prefer, $$ M_{\mathrm{atm}_\bigoplus} = \frac1{g_{_\bigoplus}}\int_{{\textstyle\!A}_\bigoplus} \!\!\!\!\! P_{\mathrm{surf}} = \frac1{g_{_\bigoplus}}\int_{\theta} \! \int_{\phi} \sin (\phi) R^2_{\scriptscriptstyle \bigoplus} P_{\mathrm{surf}}(\theta,\phi) $$ This is very slightly wrong because some of the atmosphere is further away where gravity is less, leading to a ~0.25% underestimate of the mass of $ M_{\mathrm{atm}_\bigoplus} $. The quick estimate would be pressure at sea level times total area of the Earth divided by gravitational acceleration, $$ M_{\mathrm{atm}_\bigoplus} \approx \frac{4\pi R^2_{\scriptscriptstyle \bigoplus} P_{\mathrm{sea\,level}}}{g_{_\bigoplus}} $$ Plugging in actual numbers, $$ M_{\mathrm{atm}_\bigoplus} \approx \frac{(12.6) \,\,(6.4 \times10^6\mathrm{m})^{\textstyle 2} \,(1.01\times10^5 \mathrm{kg}\,\,\mathrm{m}^{-1}\mathrm{s}^{-2})}{(9.8\,\mathrm{ms}^{-2})} \approx \underline{\mathbf{5.3 \times 10^{18}\,kg}} $$ or about 58 quadrillion American tons.

Water is rather incompressible, so integrating the density of water (1 g/cm$^2$) times ocean depth over the surface of the oceans will get you close. This is a data intensive calculation, but all the data is well known. Then, there is the liquid water outside the oceans, about 1.75% of total water, most of which is subsurface groundwater (fresh and saline). Free surface water, like lakes, is negligible. See Where is the Earth's Water.

Another 1.75% of water is frozen in glaciers and ice caps. This is the hardest to calculate because the depths of the ice caps over land and sea is not precisely known.

Using the table at the bottom of Where is the Earth's Water we find that there is about 1.34 billion cubic kilometers $(1.34\times10^9\,\mathrm{km}^3)$ of ocean and sea water. Add groundwater, and it becomes $1.36\times10^9\,\mathrm{km}^3$. Each cubic kilometer weighs a trillion kilograms $(10^{12}\,\mathrm{kg})$ so $M_{\mathrm{hydro}_\bigoplus}$ is about $\,$ $\underline{\mathbf{1.36\times10^{21}\,kg}}\,$, or 250 times the mass of the atmosphere.

Using the same source, the $M_{\mathrm{cryo}_\bigoplus}$ is about $\,\,\underline{\mathbf{2.4\times10^{19}\,kg}}$ .


Why is the north considered as up, and south as down?

There is no good reason. It's simply a convention that someone started a long time ago and that stuck. Like the question whether an hour is divided into 60 minutes and a minute into 60 seconds.

If you go to Australia, you will find plenty of maps for tourists that show Australia at the top and Europe at the bottom.


Identifying sedimentary rocks in hand specimen

When learning to distinguish between siliceous and calcareous samples you should use a handlens.  Look for quartz, feldspars or micas.  Quartz clasts may be frosted, or you may be able to see conchoidal fracture.  Calcite will be very soft compared to both feldspar and quartz, and should fail to scratch copper (or at least not scratch it very well, while a quartz rich sedimentary hand sample will scratch glass.

For really fine grained stuff, there are times when you may need to use the context of site where the sample is from if you don't have HCL.  There can be sedimentary rocks that are made up of siliceous clasts that react with HCL due to calcite in the matrix, so HCL can be misleading.  I've even found that some mudstones and limestones can have an organic odor.

Lastly, there are structures that can suggest if a sample is siliceous or calcareous.  Styolites would suggest non-siliceous while thermal alterations like liesegang banding would suggest siliceous.

The more samples you tackle, the easier it gets.


Method to determine Tmax 95th percentile in a climate data

You're heading along the right lines, but there are a few things you might want to make sure you've thought about when deciding on your method.

1. Notation

A long time ago there was an Expert Team on Climate Change Detection, Monitoring and Indices (ETCCDMI) that came up with some naming conventions for various climate indices, because it gets a bit cumbersome to talk about things like "the annual minimum of daily maxima" all the time.  They were first described in this paper:

Alexander et al. (2006), Global observed changes in daily climate extremes of temperature and precipitation, J. Geophys. Res., 111, D05109, doi:10.1029/2005JD006290

In your case, the 95th percentile of daily maximum temperature (TX) would be called TX95p.

2. Think about your science question

Most temperature time series for the last few decades will contain a warming trend, which has the effect that hot days will occur more frequently in the later part of the data than the earlier part.  You need to think about what aspect of temperature causes the impact in the system you're studying to decide if you need to detrend the data or not.  If the problem occurs when the absolute temperature exceeds some limit, then you probably don't want to detrend.  If the the system can adapt to the mean change but the problem occurs if the hot days occur in clusters, then you may want to detrend the data.

You need to make similar decisions about de-seasonalising the data, which you're currently doing by considering each calendar month separately when estimating TX95p.  In most cases it does make sense to de-seasonalise the data, particularly in places with a large annual cycle.  While you're at it, think about whether you need to analyse the whole year.  If the impact you're worried about only occurs in a particular season, then target your analysis to that season: e.g., a warm extreme in summer typically has a greater impact than a warm extreme in winter.

3. Estimating TX95p

Unless you have some specific hypothesis or protocol that needs to separate the periods, I'd use all years of data (1980-2015) to estimate TX95p.  If you're assuming that TX95p is stationary between the periods, then using more years will give you a more accurate estimate of the threshold.

  Recently, I have come across a method to calculate daywise percentiles, high daily temperature for a specific day in a year with the high temperature for that same day across all years. Days with above 95th percentile are selected as events.

What you've found here it that there's no standard way of estimating TX95p, the climatological threshold for a hot day.  A quick glance through my notes throws up various methods:

Daily climatology using 15-day window centred on day-of-year (Della-Marta et al, 2007; Fischer and Schaer, 2010; Perkins et al, 2012; Teng et al, 2013)
Daily climatology using 10-day window centred on day-of-year after detrending the data (Kreuger et al, 2015)
Daily climatology using 5-day window centred on day-of-year (Lorenz et al, 2010; Mueller and Seneviratne, 2012)
Daily climatology using 1-day window and then smoothed with a Fast Fourier Transform (Eade et al, 2012).
Single threshold value using all daily TX in summers (Vautard et al, 2013).

  I have tried to compare both the methods for a farm location. I found that previous method (monthwise percentiles) identify less number of events in comparison to the recent method.

I suspect that trying to estimate daily TX95p from just 31 values for each day of year gives very inaccurate results, whereas estimating monthly TX95p from about 930 (31*30) values is more realistic.  The daily estimates probably jump around from one day of year to the next, which would clearly be a sampling artefact, and yield values that are quite close to TX100p, so you diagnose fewer hot days.  This is why the papers listed above use various smoothing methods.


How can I get historical weather data for the United States?

This the portal for the NOAA historical records

https://www.ncdc.noaa.gov/cdo-web/search

You can specify what you are looking for (Summaries, or other), the time range, the area.

They have records starting in the 1800`s to today.


Is the area burnt in Amazonas quite smaller than the 2018 California wildfires?

It is very likely true. Most of the fires shown on TV and in maps are not in Amazonia and not in true rainforest. Quite a lot of them are not even in Brazil. The amount of Amazonian rainforest burning is therefore relatively small, and is due to land clearance and illegal logging where the trees have been cut down and what is left allowed to dry out in the sun and then burned. Out-of-control wildfires are possible in California, but not in true rainforest, which is too damp.  A few very small fires may be due to forest-dwelling natives clearing a small patch and setting fire to it for slash and burn, short-term cultivation. They will abandon it in about 5 years time when the soil is exhausted and the rainforest will gradually take over again.


Climate change is a complicated subject which is difficult to predict with accuracy.   The IPCC's predictions at least since their 3rd report (TAR) appear to be quite good, but good over the first few years or decade and a half vs good for predictions up to 2100 remains inexact and perhaps unclear.

Governments (many not all) do rely in the scientific research of the IPCC both to anticipate coming changes and determine action, but these are difficult questions, as a global effort is required to reduce the greenhouse gas footprint, and individual nations can only control their own policies.   Even if we know, 100%, the future effects of climate change, it would still be a difficult transition away from fossil fuels towards a more climate neutral approach because (If I may borrow the word from Al Gore), fossil fuels are convenient.   They're relatively easy, especially for nations that don't need to import them and they're economically viable.

That's a general outline.   The scientific predictions are important because without them, government leaders would be making policy decisions blind (as opposed to making them based on imperfect projections), and imperfect is better than blind.

There are similar predictions/estimates made across the gamut in political policy decisions.  Estimates are made on future costs of government programs and on tax policies and national debt, or trade.   We're always trying to make mathematical or scientific estimates which, in theory, help leaders make predictions for the future.

Ofcourse, sometimes, you get leaders who don't care, who don't listen to the forecasts, climate change or economic indicators.  Politics is a messy game.

  Are there any statistics which help to visualise the effectiveness of
  new scientific findings or new technology innovation inducing a change
  in government policy to help kerb climate change?

I don't know where you'd find such statistics and I've never seen any.    Statistics can be a tricky business with a long game approach like this one.   There's a lot of factors.


If water is a renewable resource, why is there water scarcity?

What I miss in the other answers is water quality.

Even is there is sufficient water available it is often of insufficient quality  for the purpose you want it for:

We often don't drink straight out of rivers
We don't irrigate with salt water

etc.

So you need to spend effort to prepare it for use. This adds to the experience of shortage.


Has recent drop in airline flights over the US had a measurable warming effect as was found after 9/11?

It's not clear yet; this is an area of active research which it itself hampered by COVID-19 social distancing requirements, according to this report on Climate Change News:

  Scientists with Nasa and European research groups hope to use clear
  skies to narrow down massive uncertainties about the warming effect of
  condensation trails – the wispy white lines that criss-cross the skies
  in the wake of jets engines.

  “The air traffic system has not been diminished to the current levels
  since the days following 9/11,” said Patrick Minnis of Nasa Langley
  Research Center, who is joining a research effort to study
  high-altitude clouds.

  “Flight groundings at the scales initiated in response to the
  coronavirus pandemic are a significant opportunity to better quantify
  the impact of air traffic on cloud cover via contrail formation.”

As to the post-9/11 effect:

  The new research builds on studies after the 9/11 suicide hijackings
  in the US grounded flights for a few days. One study, for instance,
  found that the plane-free skies had an impact on temperature
  variations in the United States, but some researchers say the findings
  might have been caused by natural variations.


Are there any techniques for imaging the deep Earth besides seismic waves?

Gravity can be used to investigate the lower crust and upper mantle (see for example Fullea et al, 2014). Satellite measurements of gravity could even be to investigate deeper structures in the mantle, like subducting slaps (Panet, 2014). However, I couldn't find any use of gravity data to probe deeper, into the core for example.

The magnetotelluric method is sometimes used for deep crustal structure. And features of the geomagnetic field, like secular variation, can be inverted to investigate as far down as the outer core (Gubbins, 1996).

However, the most common and well developed method to image the lower mantle and core is still through seismic waves.


Laboratory simulation of the Earth's magnetic field

Magnetohydrodynamic experiments intended to create laboratory analogues for the Earth's magnetic field generally use molten sodium rather than nickel. You can read about the details of one such project, DRESDYN, in this arXiv preprint.

The central part of the envisioned precession dynamo experiment… will be a cylindrical vessel of approximately 2 m diameter and length, rotating with up to 10 Hz around its symmetry axis, and with up to 1 Hz around another axis whose angle to the first axis can be varied between 90° and 45°. The inner cylindrical shell (made of copper) is immersed into a larger cylindrical stainless container with conical end parts that can later also be used to house alternative inner shells, e.g. in the form of ellipsoids.
The mechanical and safety demands for such a large scale sodium experiment
are tremendous. With a total mass of approximately 20 tons (including the sodium
in the conical end parts and the stainless steel walls) the sodium filled cylinder will have a moment of inertia of around 104 kg m2. With a rotation rate of 10 Hz and a precession rate of 1 Hz, this amounts to a gyroscopic moment of 5 × 106 Nm which requires an extremely massive basement and a careful avoidance of resonances. Further, the experiment must be fenced by a containment which can be quickly flooded with Argon in case of a sodium accident.

Exciting stuff! Here's the project website. According to a presentation at EGU this year, the building is currently under construction.
A group at the University of Maryland is conducting similar research, and has already constructed some experimental sodium dynamos.
I'm not aware of any such experiments involving nickel. Despite its high reactivity, sodium is easier to use for such experiments because of its much lower melting point and density. Nickel's melting point (1455°C) is only 83° below that of iron, so liquid nickel in an iron shell would be a tricky proposition.


What was the percentage of land mass in prehistoric times when temperatures were high enough that we had no ice caps?

The real cause rising temperatures is not frozen ocean turning back into water but the volume of the ocean itself expanding (water expands just like everything else when you heat it), and ice on land melting and flowing into the ocean (adding more water).

Ice sheets can be tricky to predict but it has been included in this report . Although for the most part ic just say whether it exists or not reconstructing total volume of ice is currently not something we can determine accurately.

This chart from that report show how ocean temperature and sea level correlate.

This paper shows how the two factors compare, they are are mostly comparable but ice melt (mostly glacier) is starting to overtake expansion. Great chart on page 1157.

As for historical rise, earth used to have two ice sheets, one at each pole (this was responsible for the Asia-North America land bridge), but the northern one has almost completely melted, except for greenland, that is why we had historical sea level rise. There used to be thousands of feet of ice over boston. Land locked ice sheets are very sensitive to temprature, easy to melt, island ones like greenland and antarctica on the other hand create their own sort of insulation by altering circulation. These latter ones are much harder to melt, you need a much greater rise in temprature, which we have created. The last big melt turned england into an island.


Impacts of high-altitude emission of greenhouse gases (GHG) compared to sea level GHG emissions

I think you may be confusing two separate, but related, issues.  Aircraft emissions at high altitudes are a concern for the ozone layer, because the NOx that is emitted by aircraft can catalytically destroy ozone.  Supersonic aircraft fly higher up in the stratosphere than a typical jet, and thus can harm the ozone layer more effectively.  The ozone layer is related to climate change, which is perhaps why you are mixing two issues.  For the most part, aircraft greenhouse gas emissions are not a concern simply due to the altitude they are emitted.  Instead, aircraft GHGs are a concern because they are long-lived in the atmosphere and well-mixed, causing "global" warming.  Furthermore, aircraft emissions are expected to continue increasing for decades.


Can miniature shells be seen in Earth's sand at this resolution?

Firstly I would disagree with your premise that 'most of Earth's sand contains tiny shells resembling sea shells'. Such biogenic sand is certainly true of some biologically productive sedimentary environments, but certainly far from all. For example, try finding shells in most of the sand in the Sahara desert, or any other desert for that matter. You will only succeed if the sand is reworked from previous biogenic sandstone.

As to the resolution of shells at the apparent scale of your photograph, it depends upon the biota involved. The bioclasts vary from several millimetres to true microfossils - far below any visible resolution, and maybe even below resolution of small microscopes.

I assume that any close up photo of Mars sand would have been magnified, contrast stretched, and computer image enhanced. Had there been any bioclastic grains, I am sure it would have been front page news around the world.


How much methane clathrates are buried in continental deposits?

According to Role of methane clathrates in past and future climates,

  Methane occurrences and the organic carbon content of sediments are
  the bases used to estimate the amount of carbon currently stored as
  clathrates. The estimate of about 11,000 Gt of carbon for ocean
  sediments, and about 400 Gt for sediments under permafrost
  regions...

So 400 billion tons.


How do tropopause folds form and do they have any impact on synoptic scale weather?

I am not not an expert in meteorology, but do study the chemistry involved in these types of events.  My understanding is that the folds in the tropopause generally occur below the front of the jet stream, when the potential vorticity is strong enough to transport stratospheric air down through the tropopause/inversion.

Please see the relevant quote from Q. J. R. Meteorol. Soc. (2004), 130, pp. 1195–1212 doi: 10.1256/qj.03.21
Convective mixing in a tropopause fold
By H. J. REID and G. VAUGHAN∗
Institute of Mathematical and Physical Sciences, University of Wales, Aberystwyth, UK

"Mixing between stratospheric and tropospheric air can occur most readily in deep
intrusions of stratospheric air into the troposphere, such as tropopause folds (Danielsen
1968). They occur because of the ageostrophic circulation at the jet entrance (Hoskins
1982) and coincide with the frontal zone beneath the jet. Deep folds can extend down to
the top of the boundary layer (Browell et al. 1987; Vaughan et al. 1994), while smaller
folds, extending only into the upper troposphere, are ubiquitous around the polar jet
stream (e.g. Vaughan et al. 2001). They also occur beneath the subtropical jet stream
(Gouget et al. 1996), where it has been suggested that mixing between the subtropical
fold and tropospheric air promotes the generation of new aerosol particles (Zahn et al.
2000). Turbulence within folds can result from shear instability beneath the jet (Pepler
et al. 1998; Hartjenstein 2000) or from convection extending up from the boundary
layer (Browning and Reynolds 1994)."

As for synoptic scale weather, I don't think a tropopause fold affects the synoptic scale weather events much, but are rather a part of the weather events.  The downward mixing of stratospheric air will introduce drier air, leading to lower humidity in the general vicinity.  Of course, ozone will be entrained into the tropopause as well, which has air quality implications.  And there are certainly feedbacks in the fold phenomena that will affect heat, radiation, and kinetic patterns... but the synoptic weather in the region is going to be more driven by the jet stream itself rather than a fold that may occur.  A meteorologist, though, might have better information on that.


Difference between NCEP's 20th Century daily Forecast and Analysis variables

Some variables in reanalyses have to be forecast and cannot be assimilated to allow the model to converse mass, momentum and energy. Precipitation is a good example. The model will assimilate observations which give information about moisture (someone who knows more about assimilation may want to chirp in here). This will be used in the analysis (e.g. 00z) and is forecast forward. Daily precipitation is therefore given as the accumulation of precipitation from 00z analysis -> 12z forecast and the 12z analysis -> 24z forecast.

There is a hierarchy of precipitation datasets each with pros and cons:

Gauge data is often considered the best but it very patchy (not to mentions instrument issues). You can use kriging to make spatial maps. This paper may be of interest.
Satellite datasets such as GPCP and TRMM give better spatial information but subject to issues over land, for example (I think). The are also subject to trackiness (only get data underneath/near the satellite).
Reanalyses can provide spatial and temporal homogeneity but it is a model and 'all models are wrong, but some are useful'.
Datasets are emerging combining both gauge, satellite and reanalyses such as in this paper.


Wouldn't a more beneficial method of disposing of such waste be to find a method of isolating them from the effects of weathering and keeping the carbon they contain locked up as long as possible?

You are ignoring a number of factors here.

A good deal of energy, much of it non-renewable, is needed to turn trees into paper. The trees need to be cut down (requires petroleum), transported to the saw mill (more petroleum), sawed and chipped (requires electricity), transported again (more petroleum). Once it gets to the paper mill, it needs to be pulped (requires petrochemicals, which need to be transported (requires petroleum)). The pulping process also consumes a good deal of electricity, as does the process of turning pulp into paper.

Bottom line: Paper has a positive carbon footprint.

If you send that paper to a landfill after using it, the carbon in that paper will be released to the environment, and in fairly short order. On the other hand, recycling paper bypasses a number of the steps involved in turning trees into paper. Turning paper into pulp is easy. Recycling paper reduces paper's positive carbon footprint by a significant amount.

The question specifically asks about finding a method of isolating wastes from the effects of weathering. That's not easy. Anaerobic bacteria find paper to be quite yummy. A deep ocean trench might work, but it would be better to not make paper in the first place. Growing and harvesting trash trees and then sending them into the deep would be more effective. A number of early geoengineering proposals suggested doing just that. There are big problems here, mostly unintended consequences. Deep sixing trees in deep ocean trenches is no longer viewed as a viable carbon sequestration scheme.