How is phosphorus getting into lakes and rivers?

Phosphorus & phosphates are a key component of agricultural and garden fertilizers. Most plants need nitrogen (N), phosphorus (P) and potassium (K). They are generally combined into one product called NPK fertilizers.

Nitrogen is needed for leaf growth. Phosphorus is needed for roots, flowers, seeds and fruit and potassium is needed for stem growth and water movement.

The trouble with the use of fertilizers is they get dumped onto plants periodically and the plants cannot use all of the elements in the fertilizer at that time. What isn't absorbed by plants eventually is leached from soil via rain or irrigation water and it ends up in rivers, streams and sometimes lakes.

In Australia, phosphorus can  be toxic to some native plants because over millennia Australia's, so called, soil, have been depleted of phosphorus and plants evolved to live with either no or very little phosphorus,


Will the Southern Ocean act as a net source or sink for atmospheric $\ce{CO2}$ in the future?

I think you may have misunderstood the abstract of the paper, which says:

  Various human activities, including fossil fuel combustion and forest
  clearing, emit about eight petagrams (or billion tons) of carbon in
  the form of CO2 into the atmosphere annually. The global ocean absorbs
  about two petagrams of CO2, and about a half of that amount is
  absorbed by the Southern Ocean south of 30°S, thus slowing the rapid
  accumulation of CO2 in the atmosphere. Partial pressure of CO2 (pCO2)
  is a measure of the chemical driving force for the CO2 exchange
  between the ocean and the atmosphere. This paper discusses its space
  and time distribution over the Southern Ocean. The major sink zone for
  atmospheric CO2 is located in a latitude belt between 30°S and 50°S,
  where the biological utilization of CO2 and cooling of warm
  subtropical waters flowing southward produce low seawater pCO2.

Note that most of the "half of the global ocean total absorption" occurs in a band between 30°S and 50°S.

  Strong
  winds in this zone also enhance the ocean's uptake. Although the
  source-sink conditions vary over a wide range through the seasons in
  the areas south of 50°S, this zone is a small sink on an annual
  average. Winter observations show that surface water pCO2 values in
  the source region for Antarctic Intermediate Water have increased at a
  rate faster than the atmospheric increase rate, suggesting that the
  ocean CO2 sink intensity has been weakening for several decades and
  has changed from a net sink to a net source since 2005. The results of
  ocean general circulation-biogeochemistry model studies are found to
  be consistent with the observations.*

The "net sink to a net source since 2005" appears to relate to this area south of 50°S, which was only a small sink to begin with.  This suggests that the southern ocean as a whole is still a strong carbon sink.  As the evidence for an increase in the airborne fraction increasing is currently equivocal, this suggests that the natural carbon sinks (including the southern ocean) is still strengthening in response to increasing atmospheric concentrations.

Note the conclusion of the paper talks of the 30°S and 50°S being a sink in the present tense, which would be inappropriate if it had become a net source since 2005.


Does earth's size affect the temperature of the poles?

The primary factor determining the temperature of a planet is the radiation it receives from its sun.  If this were the only factor, it would be possible to estimate its temperature using the black body radiation law, as described e.g. on Wikipedia.  Based on this calculation, the size of the planet has no effect on its temperature.

However, there are other factors contributing to the temperature of the planet, such as its atmosphere (greenhouse effect), internal heating due to radioactive decay, and the surface reflectivity, affected by such things as plant or snow cover, etc.  All these can and have changed in the past.

The black-body approximation gives a temperature of about -18 C, thus the other factors have a smaller but still significant contribution.

So the question is how are the other factors affected by the size of the planet?

Effect of the atmosphere: I cannot comment.
Internal heating: the heat generated by radioactive decay is proportional to the amount of radioactive material, i.e. the volume of the Earth (proportional to its radius $R$ cubed, $\sim R^3$), assuming a fixed density and composition.  The heat loss is proportional to the surface area ($\sim R^2$).  So the larger the planet, the higher the temperature increase coming from internal heating.


Can spraying sulphate particulates in the upper atmosphere to lower Earth's temperature have side effects?

Short Answer yes, there may be side effects.

Long answer. They are looking at more than just sulfates. Initial research has shown an optimistic lack of side effects for sulfates but we won't know until we actually test it and testing over a 1km area, something attempted multiple times, has been blocked for environmental concerns. Concerns exist because we can't test it because it's blocked for environmental concerns.

The thing to keep in mind is that the original idea was

proposed to shock the scientific community into researching multiple avenues by Lowell Wood in 1999 (I could not find the source but it was a Wikipedia article so take it as you will.)
is based off the cooling effects of volcanoes.

The second point is the most important because we have a natural phenomenon to work off of. there was a volcanic eruption in the 90s that lowered global temperatures by ~1.5 degrees (I believe it was C) over 18 months before things returned to normal. This means we can study the effects of volcanoes and predict the effects of the aerosol injection. Side effects of volcanoes include large impacts on vegetation and cooling but little else is cited in the articles I've seen. Fortunately, they believe that aerosolized injection into the upper atmosphere will avoid affecting plants very much if at all as the particles will mostly stay up there. However, there is concern that it might modify our atmosphere in some unknown way.

I have seen some articles saying sulfur emissions in China/asia might actually already be helping lower global temperatures a little but the idea was theoretical and the articles mostly seemed like clickbait.

Really we aren't sure and need to do some testing to find out. However, this will be small scale testing that will ramp up slowly.


Where on Earth has the least changing temperature?

To answer the first question, yes, there are maps showing the seasonal temperature variation, for example here

Unsurprisingly, the equatorial areas have the least variation because the angle of the sun relatively to the earth changes the least with seasons.

Regarding nice weather- I have worked as a geologist in northern South America and the Caribbean. In the lower lying areas (e.g. Aruba) I often thought it was too hot to be pleasant to work, but beachgoers think that was perfect weather. In the mountains it was often more pleasant, subjectively.
One city I visited where the temperature is remarkably stable is Medellin in Colombia - the "city of eternal spring". Situated close to the equator, temperature is always nice there (daily mean at 22 degrees throughout the year), but it can have a lot of rainy days.


What is the steepest surface that can hold snow?

What's the minimum "uprightness" for it to not get obscured by snow and stay readable throughout the year?

The answer to this problem is not in the angle at all. No amount of math will give you an angle at which you can reasonably presume your surface will remain clear. Snow can (and does) accumulate on vertical and even negatively sloped surfaces. Instead of thinking about the angle, you should be thinking about the materials and conditions involved.

There are lots of factors that determine whether snow will stick, but a few that stand out most are:

Temperature differentials between a surface and the atmosphere:

This is particularly noticeable on surfaces of enclosures such as vehicles or buildings where the internal temperature causes the surface to be out of sync with the environment. You might notice snot collecting on the vertical glass surface of car side windows. This will be more pronounced in cars that were parked full of warm air when it started snowing. The warm glass would have melted the initial snow flakes. The wet surface will eventually freeze giving  a textured surface for new snow flakes to sit on instead of sliding off.

The same is true for objects with thermal mass that retain heat or cold after a sudden change in air temperature.
Surface properties such as roughness.

If even a few snow flakes find purchase on a surface, more will  find a way to build on that and obscure your surface. This is far more important than angle.
Atmospheric conditions such as humidity and the nature of the snow fakes formed.

To effectively keep a surface clear it should be ① smooth, ② quickly transfer heat to adapt to the current air temperature, and ③ be sheltered from being in contact with falling snow in the first place. Even highway signs with are smooth, vertical and thin metal are only so effective  at staying clear and in some regions will have eaves protecting them from some snowfall.


Everything you did looks reasonable.  There is one error in the 'net inflow into lake' line where you take the area of the lake to be $100\cdot10^3\ \text{m}^2$ instead of $100\cdot10^6\ \text{m}^2$, but that might just be a typo.

In general, this type of problem is much easier to work (especially when you think you've made an error) by keeping everything symbolic.  For your problem I would define the variables

$i$: inflow into the river in $\frac{\text{m}^3}{\text{s}}$
$o$: outflow from the river in $\frac{\text{m}^3}{\text{s}}$
$r$: inflow from rain in $\text{m}$
$e$: evaporation in $\text{m}^3$
$\Delta h$: change in height of the lake in $\text{m}$
$A$: area of the lake in $\text{m}^2$
$\Delta t$: time period in $\text{s}$

The equilibrium equation is then

$$\text{sum of inflows}-\text{sum of outflows}=\text{change in storage}$$

which is written in terms of the defined variables as

$$i\ \Delta t+r\ A-o\ \Delta t-e=\Delta h\ A.$$

You can check that this equation at least makes sense in terms of units by observing that all of the terms have units of volume, i.e. $\text{m}^3$.  Finally, you can rearrange the equation to solve for the variable of interest;

$$e=(i-o)\Delta t+(r-\Delta h)A.$$

At this point you can plug in the numbers.


Hi:  Your rocks are not geodes but likely concretions.  The wiki article even mentions concretions from Kansas though the concretions described don't to me fit what I see in the images.  Better pictures and more description about the rocks would lead to better identification.  See Better rock ID requests

Wiki's Concretion Page


So will a tangerine sun loom large over red-hot waves softly breaking on abyssal beaches?

Probably not. Interesting question, and one might think that yes - you could melt the evaporite deposits that will be left after all the water is gone.

The problem is that molten salts are extremely reactive materials. They will corrode any rock they get into contact with. As most rocks on the ocean floor are silicates (basalts etc) you will just get chloride-silicate minerals. For example, the reaction between halite and nepheline (a fairly common silicate mineral) will lead to the formation of sodalite (another fairly common mineral):

$\ce{6NaAlSiO4 + 2NaCl = Na8(SiAl)6O24Cl2}$

There's a long list of known chloride-silicate minerals, and for a more realistic salt–basalt reaction the products can be things like scapolite, adrianite, or wadalite.

You will most likely end up with no salt, overlying a somewhat thin (metres?) layer of these silicate-chlorides. It could be that in some points you might have ephemeral pools of liquid salt, or in places where the chloride-silicate layer is thick enough to effectively isolate the liquid salt from the silicate rocks below, but those will probably be negligible features on the scale of the planet.

One final comment:

  quartz melts at 1713C

In isolation. When quartz is mixed with other things (like feldspars in a granite), it melts at a lower, eutectic, temperature.  See related question one and two.


Is Mississippi and parts of Alabama, Tennessee, and Kentucky one giant island?

Rhetorical questions:

Does the Erie Canal, which connects the Hudson River with Lake Erie make northern New York, southern Quebec, all of New England, all of New Brunswick, and the non-island parts of Nova Scotia an island?
Does the Chicago Sanitary and Ship Canal make all of the eastern part of the US an island?
Does Russia's Unified Deep Water System make Finland, Scandinavia, and Estonia an island, and mainland Europe another island?

Humankind has learned to connect waterways with canals, locks, and dams. The sudden appearance of those canals, locks, and dams does not suddenly make those now disconnected lands into islands. The connection between the Tombigbee and the Tennessee rivers involves manmade canyons, manmade canals, and several manmade locks and dams.

What about naturally narrow waterway connections? As an extreme example, consider the Committee's Punch Bowl in Alberta, Canada. This little lake has two little outlets. One of the outlets eventually joins the MacKenzie River, which flows into the Arctic Ocean. The other eventually joins the Columbia River, which flows into the Pacific Ocean.

This leads to one last rhetorical question: Does the natural existence of the Committee's Punch Bowl make most of Washington state, most of British Columbia, almost all of the Yukon, and all of mainland Alaska into a very large "island"? Most geographers would say no.


Are La-Nina and positive Indian Ocean dipole similar?

The Indian Ocean dipole is essentially a measure of the difference in sea surface temperatures between the western and eastern Indian Ocean.

The El Nino and La Nina are the opposite phases of the El Nino Southern Oscillation cycle that occurs in the Pacific Ocean.

The only similarity with the Indian Ocean dipole, is that the difference between the sea surface temperature between the central western Pacific Ocean & central eastern Pacific Ocean are measured.


Is the colour of soil determined by the 'proteins' present in soil?

Soil is a collection of minerals and the color of soil is largely determined by the composition of its minerals.

Protein is derived from biological sources. The only way proteins could affect the color of soil is if the soil also contained large quantities of biological material.


The straight answer is no. The definition of a glacier requires the body to be of ice and snow, to move and deform under its own weight. If the body is pure ice the pressure needed to make ice deform corresponds to about 30-40 m of ice pressure.

The definition makes any body not consisting of ice and snow not a glacier. As an example, so-called "saltiers" are bodies of rock salt that move like glaciers. You find such features in the southern part of Iran. They would not qualify as glaciers from the first part of the definition.

The second part says that they must move. In mountainous terrain snow packs and also thin features of ice can move because they slide downhill. Because these are too thin there is no internal definition so the third part of the definition prevents such features from being glaciers.

Hence what remains are bodies of ice and snow that have sufficient thickness to induce deformation and hence they will be of a  minimum thickness.

As a glaciologist, I do not find this definition very academic. With glaciers reducing in size around the globe many glacier will, in time, pass the limit and cease to be glaciers but knowing when this happens requires physical measurements which for practical reasons (and current technology) can only be made on a  very small subset of the about 160 000 glaciers (not counting the ice sheets) on the earth. It is hence of little practical use when trying to figure out when particular glaciers cease to fit the definition.


I think it is stratocumulus. Sometimes it rolls like that. Nice picture


What wind speeds and gusts can usually damage houses or trees?

This Beaufort Scale of Wind Force image may help answer your question.

source: strleng.blogspot.com


Could glacial melt alter plate tectonic movement?

Yes, it's called glacial rebound. Some areas of the globe are still responding to the disappearance of the ice of the last ice age. A well known example of this are the raised beaches in the northern Baltic, where the crust is rising due the melting of the ice sheet that covered Scandinavia.


What are the band names of the NCEP grib files?

This file is in GRIB-1 format. Each band corresponds to a GRIB message. The band names can be found in an INV file on the same server.

For your example check out the corresponding inv file ftp://nomads.ncdc.noaa.gov/GFS/analysis_only/201501/20150103/gfsanl_3_20150103_0000_000.inv.

Another option is to use wgrib -v with -v  option.

The band names and offsets for all 315 bands can be obtained this way, e.g. for band 2

2:81534:D=2015010300:VGRD:planetary boundary layer (from Richardson no.)
 :kpds=34,220,0:anl:winds are N/S:"v wind [m/s]

That is bands 1 and 2 store u and v components of the wind speed at the boundary layer.

kpds parameters make up the product definition section identifiers. The first kpds number can be mapped to mnemonic GRIB identifiers, i.e. number 34 maps to VGRD.

The unit is m/s and the data representation is 64-bit floating point. The latter piece of metadata can be extracted from the GRIB file itself e.g. using gdalinfo.

Band 2 Block=360x1 Type=Float64, ColorInterp=Undefined
  Description = 0[-] var220 (reserved)
  Metadata:
    GRIB_COMMENT=v-component of wind [m/s]
    GRIB_ELEMENT=VGRD
    GRIB_FORECAST_SECONDS=0 sec
    GRIB_REF_TIME=  1420243200 sec UTC
    GRIB_SHORT_NAME=0-var220
    GRIB_UNIT=[m/s]
    GRIB_VALID_TIME=  1420243200 sec UTC

With the -V option wgrid utility produces a more detailed output:

rec 2:81534:date 2015010300 VGRD kpds5=34 kpds6=220 kpds7=0
    levels=(0,0) grid=3 planetary boundary layer (from Richardson no.) anl:
  VGRD=v wind [m/s]
  timerange 10 P1 0 P2 0 TimeU 1  nx 360 ny 181 GDS grid 0 num_in_ave 0 missing 0
  center 7 subcenter 0 process 81 Table 2 scan: WE:NS winds(N/S)
  latlon: lat  90.000000 to -90.000000 by 1.000000  nxny 65160
          long 0.000000 to -1.000000 by 1.000000,
          (360 x 181) scan 0 mode 128 bdsgrid 1
  min/max data -38.8 45.4  num bits 10  BDS_Ref -388  DecScale 1 BinScale 0


Any historical examples of destructive climate warming?

To answer the question

  Are there any known or suspected historical i.e. Holocene climatic warming associated with negative impacts on human populations?

One recent (actual) example that come to mind is the sea level rising. Here we see that since the early satellite measurements in 1993, sea level rise was about 8 cm. On the same page, less reliable gauges indicated a coastal sea level rise of 20 cm between 1870 and the late 1990.

Some Islands are particularly vulnerable to sea level changes, in regard with fresh water supplies, soils and shore degradation following storms and strong high tides, etc. Marshall Island (~2 m), Maldives (~1 m) are examples of emplacements with very low mean ground level. It is really a question of time before these places become unlivable.

While these are small islands, other populous places are quite vulnerable to similar situations such as Bangladesh.


Why does radioactive dating work on specific rocks?

There are other, mostly chemical processes which alter the isotope ratios. Isotope dating uses a combination of them. This is why it can not be used always, for any radioactive isotopes, only in special circumstances. It also requires very sensitive measurements (below in the second example, close to induvidually count lead atoms in microscopic zircon crystals).
For example, in carbon dating, C14 is continuously generated in the atmosphere due to the cosmic radiation, and builds in the biosphere, where it decays. If a plant stops accumulating carbon ( = it dies), its C14 ratio starts to decay.
Another example, this time about isotopes which were created really with the Solar System. The mineral zircon ($\rm{ZrSiO_4}$) accumulates uranium and thorium atoms in it crystal structure, but strongly rejects lead. This rejection can happen as it freezes. After it is solid, the lead atoms created by U/Th decay do not go away any more. Thus, all the lead in the zircon crystals of the soil of Moon, were created since it frozen. This makes possible to know, when did that zircon solidify ($\approx$ when formed the crust of the Moon).


With respect to latitude and time of year, what geopotential heights are associated with low pressure systems on the North American landmass?

Great question!
First, let's look at typical data: here are the 1981-2010 Reanalysis mean and standard deviation:

So looks like the mean 500 height in September for Wisconsin ranges from about 571-580 Dm, with a standard deviation of 36-42 Dm.  These are mean pressures, not lows or highs, so already, not that far off your low.  If (a big if) meteorological statistics are normally distributed, using this calculator, this would suggest a 560 Dm height would be in about the 29th-40th percentile, depending upon location.  A little lower than usual, but apparently fairly typical.

And just for good measure, looking back at the University of Wyoming, I was able to fairly quickly come upon:

A 554 or 555 Dm low.  If you want to look for more images (perhaps even the event you are reading about), you could also look in the Pix directory for the dates of interest at Iowa State's MTArchive.

But it appears that 560 Dm would be a fairly typical height for a low/trough during early fall.  Some people might still call it deep (30 Dm of contours on that plot from September would be fair), but it's nothing too abnormal.


Difference between isotherms and isotheres

The general term isotherm refers to a line of equal or constant temperature, while isothere refers more specifically to lines of constant average summer temperature.

For what it's worth, coming from a background in forecasting and research centered around active weather rather than longer-term climate, isotherm is an extremely commonly-used term in weather discussions but I can't recall ever seeing isothere used in practice before now.


Implications of recent 36 degrees Fahrenheit (20C) anomaly at North Pole?

The specific 36 F temperature anomaly in the linked article points to a single day event. I am aware that it is associated with unusually high temperatures in general this fall/winter, but a single day event is not that unusual. For example, the average January temperature in Dallas is 46 F, and the average monthly high is 76 F. That means every year (on average) sees a temperature that is 30 F above normal. The record high in January is 88 F, meaning that at least once, the temperatures in Dallas were 42 F above normal. That was all the way back in 1969.

While this doesn't look great for the polar bears, and is further confirmation that AGW is coming along nicely, I would caution against getting too upset about it in the short term. We aren't out of time yet. After all, the world didn't end after that record January heat in 1969.


How to understand the bizarre high level for both PM2.5 and Ozone

I think it is important to keep in mind the mechanisms that form PM$_{2.5}$ are different than the mechanisms that form O$_3$.

From the data your provided you can draw some simple conclusions:

Increasing SO$_2$ increases PM$_{2.5}$
Increasing NO$_2$ increases PM$_{2.5}$
Increasing NO$_2$ doesn't necessarily increase O$_{3}$

The last point is what you seem to be struggling with. I think what you see here is 'the weekend effect' where lowering the NO$_2$ concentration increases O$_3$ concentration. In this effect, the generation of nitric acid and the destruction of O$_3$ by NO ($\ce{O_3 + NO → O_2 + NO_2}$) decreases the ozone, but increases NO$_2$. I think this explains the phenomenon seen.


Hypotheses about Silurian carbon isotope excursions?

Even though many researchers now recognise that the Silurian palaeoclimate show signs of large fluctuations - resulting in the carbon excursions, the mechanism behind the climatic shifts is not well understood.

Recent research from Munnecke et al. 2014 (1) suggest that the carbon (and oxygen) isotope excursions that mainly affected low latitude palaeoenvironments, were probably due to climatic shifts between humid (low C) and arid (high C) climatic conditions. The possible consequences of these two climate regimes is shown below:

One of the only certain climatic regimes that occurred was in the early Silurian, where 3 of the 7 'Early Palaeozoic Icehouse' (EPI) events occurred (2).  Munnecke et al. 2010 (3) note that much of the Silurian is 'sandwiched' between the EPI and the greenhouse of the Devonian, possibly suggesting a prolonged transitional period between the 2 climatic regimes.

Some observations suggest that sea levels fluctuated very wildly, Munnecke et al. 2010 (3) states they were up to the order of 140 m.  This is partly related to recent oceanic circulation modelling performed by Servais et al. (4) who state that the palaeogeography of the time (large northern ocean and the Gondwanan land mass at the south pole - see below) would have possible resulted in a halothermal circulation, rather than the modern day thermohaline circulation, essentially due to the restrictions a possible Mediterranean-like production of denser water at the lower latitudes (as indicated in the diagram above).

Image source

So, in summary, the oceanic-atmospheric interaction of the Silurian is considered to be unstable (1)(3), with oxic and anoxic regions uncertain (4), but the effects were clearly seen with variations in the climate from humid to arid and large fluctuations in sea levels.

References

(1) Munnecke et al. 2014, Silurian climate development University of Nuremberg

(2) Page, A., Zalasiewicz, J., Williams, M., Popov, L., 2007. Were transgressive black shales a
negative feedback modulating glacioeustasy in the Early Palaeozoic Icehouse? In:
Williams, M., Haywood, A.M., Gregory, F.J., Schmidt, D.N. (Eds.), Deep-Time
Perspectives on Climate Change: Marrying the Signal from Computer Models and
Biological Proxies: Special Publication of the Geological Society of London. The
Micropalaeontological Society, pp. 123–156

(3) Munnecke et al. 2010, Ordovician and Silurian sea–water chemistry, sea level, and climate: A synopsis Palaeogeography, Palaeoclimatology, Palaeoecology

(4) Servais et al. 2014, Possible oceanic circulation patterns, surface water currents and upwelling zones in the Early Palaeozoic Special Issue:   EPGC - Early Palaeozic Global Change


How to strong winds cause baroclinic intensification in the upper ocean?

Strong upwelling-favorable winds (like the ones described) cause coastal upwelling in the following manner:

Winds in these systems flow parallel to the coast (with the coast to the left in the northern hemisphere or to the right in the southern hemisphere) and generate upwelling dynamics.
Surface Ekman balance is setup (in deep enough waters) with water transport being to the right (left) of the wind in the northern (southern) hemisphere. The result is a deficit along the coast that requires a compensating flow in the deeper part of the water column bringing usually colder waters to the surface.

 Source Commons Wikipedia.

The resulting density (mostly controlled by temperature in these systems, but sometimes affected by salinity in areas with river influences) shows a strong horizontal gradient. A strong horizontal gradient in density is the definition of strong baroclinicity. That strong gradient can even be visible in a temperature front when the thermocline reaches the surface (SST image below).
Additionally, the density gradient can establish a thermal wind balance that results in a coastal upwelling current jet flowing in the same direction of the wind. The horizontal gradient in density is proportional to the vertical gradient in velocity
$\mathrm{{\delta\rho\over\delta x} \propto {\delta v\over\delta z}}$ . As velocity is zero at the bottom, this results in a strong velocity near the surface. This is what we understand as "intensifying the baroclinicity in the upper layer".

 Source: Satellite image of SST showing multiple upwelling centers and cold filaments off central California (Courtesy of E. Armstrong).


What is the distribution of global photosynthesis?

You are perhaps looking for primary production.

That is a measure for the total amount of biomass produced. Primary production is measured in two different ways, gross primary production, that is simply everything produced by the photosynthesis, and net primary production, that is the same, except for that the amount consumed by the plants is subtracted.

The estimates are about 115 gigatons of carbon per year of net production on land, and 55 gigatons of carbon per year for the ocean.

Roughly $\frac{2}{3}$ on land and $\frac{1}{3}$ in the ocean.

Cultivated land contributes to about 9% of the net production on land.
Read more about that here.

Below is the annual average of the net productivity of vegetation on land and in the ocean during 2002 (from http://science.nasa.gov/earth-science/oceanography/living-ocean/remote-sensing/ )


There are many reasons.

First, measuring from sea level is traditional. It started before we had an accurate way of measuring distance from the center of the Earth, and probably before most people knew it was (approximately) a sphere.  But anyone living by the shore could determine sea level to within a few feet.

Another reason is that measuring from sea level tells you useful things like pressure altitude, which are important if you're a pilot or mountain climber.  The polar and equatorial radii differ by about 14 miles (21 km), so depending on your location, a distance of say 6,365 km from the center could be deep underground or halfway to the stratosphere.


When the flow of water in a river accelerates, it can pick up more sediment from the river bed and transport it downstream. Alternatively, when the flow slows down, the transport capacity drops and the sediments suspended are deposited on the river bed.

When a river goes into a lake, it transitions from the fast-flowing regime in the river to a very slow flow in the lake. Therefore, sediments are deposited as a result of the slowdown, forming a delta.
The inverse happen at the outlet of the lake, where the water accelerates. Therefore there sediments tend to be picked up and transported downstream, not allowing to the formation of a delta.

However, this only partially answer your question, because the terrain around lakes is very often flat, one would might expect to see plenty of examples of lakes being drained by multiple rivers. The answer to this is that multiple rivers in parallel are unstable: if one of the rivers becomes slightly larger, it will have more and faster flow. Therefore, it will increase its capacity to transport sediments, digging into its bed and growing even bigger. If it grows bigger, the sediment transport will increase further and the river will grow even more. This positive feedback leads to the grow of the largest outlet at the expense of the smaller ones, until you have only one river outlet.

However, it takes time for one outlet to monopolize the flow. And in very flat and changing terrain you can find lakes drained by a delta. One example of this is the proglacial lake of Kaskawulsh glacier in the Yukon Territory, Canada:

This lake is in a divide. And it is drained not by one, but by two deltas. Interestingly, the Slims river in the top of the picture has reversed its flow direction in historical times.

In this NASA Earth Observatory article, you can find out more about this interesting river and some great images, plus comparisons of how the flow regime has changed in the past.


It doesn't stay frozen.  Ice evaporates (or sublimates is the correct term) under direct sunlight, but that's at a molecular level, it doesn't melt, it goes from solid to gas under sunlight and in the cold, some of this newly formed water vapor goes back being to ice.

In an absolutely dry climate, well below freezing, ice would slowly sublimate and disappear.  In a warm dry climate, ice would melt (much faster), then it would evaporate.   The sun does sublimate ice off the antarctic ice sheet every day, but quite a bit less than is added by snow and condensation from moisture due to temperature change and brought over by wind.   The antarctic ice sheet is also, always moving.   Mostly Antarctica loses ice by pushing it into the ocean - over long periods of time and it gains ice by (see above) snow and condensation.   The ice has been on Antarctica for over 30 million years, but as far as I know, the oldest ice core we've found there is about 1.5 million years old.    Everything moves.


How to perform regridding (1.0d to 0.5d) using bilinear interpolation for an irregular area?

Try something like this:

[x_grid,y_grid] = meshgrid(1:100,1:100);
z_grid=griddata(x_data,y_data,z_data,x_grid(:),y_grid(:),'v4');

You can change the method of interpolation if you prefer something else.

See:
http://www.mathworks.com/help/matlab/ref/griddata.html


Why is there no desert in Southeast China?

This is a very active region for tropical storms.

NASA


Can Venus be considered to be tectonically active?

There has been some considerable modelling about this particular scientific issue, as it is considered important to understand Venusian tectonics to be able to get a better understanding of Earth tectonics (1).

So, in answer to your question, is Venus tectonically active, the answer from current research suggests that it is not - but not at the moment, especially not like Earth. Much of the research refers to Venus as currently possessing a "stagnant-lid" single plate (1),(2), (5).  The tectonic-like features found on Venus have not been observed to 'fit' a global pattern that would suggest a 'mobile-lid' tectonic regime like that of Earth (1). Much of the recent research has not really focused much on the differences between Earth and Venus - including, the Moon, liquid water and differences in rotation, but rather focuses on what observations of orbiting spacecraft, such as Magellan and the Venus Explorer have revealed and what models based on these have deduced.

Recent research has painted a picture that the answer to this question is considerably more complex than would justify a 'yes' or 'no' answer.

Modelling from gravity and topographic anomalies observed by several of the space craft that we have sent to Venus suggest that many of these features are derived from 'hotspot' upwelling mantle plumes where partial melting could occur (2).  This is supported by an example of a recent re-evaluation of earlier observations of tectonic-like features on Venus was performed by McGovern et al. (2014) (3) of Magellan images, using stereo radargrammatic images, of the graben-like structures that extend from the Venusian shield volcanoes reveal that they, alongside the radial dike emplacements, are accounted for by magma reservoir expansion (1).

Models reported by Huang et al. 2014 (2) also suggest that Venus has a very thick lithosphere compared to that of Earth, which would support the high topography noted for Venus (5).  Related to this is that in deformation experiments, Azuma et al. 2014 (4) suggest that is a mechanical decoupling of the Venusian crust and the mantle convection (as shown in the diagram below (4)).  Huang et al. (2) models also have found that Venus cannot have a weak asthenosphere in the way that Earth does.

So, coming back to what I meant about not being tectonically active 'at the moment' in the first paragraph.  This comes from the observation that the entire planet seems to have been resurfaced approximately 750 million years ago, evidenced through the amount of craters and other features (1).  This has lead to some researchers, such as Turcotte, 1993 (5) to suggest that tectonic activity on Venus is episodic. The process is hypothesised by Head, 2014 (1) as comprising 3 stages:

A relatively short phase of intense tectonism, as indicated by the tesserae, high plateaus, plains deformation and coronae - Turcotte (5) theorises that the formation of coronae could be an indication of a new episode of tectonism.
A relatively short phase of intense volcanism, with minor subsidence and deformation.
A long period of network rifting (graben formation, modelled to be hotspot induced (3)) and volcanism.

Recent modelling by Gillman and Tackley (2014) (6) provide a possible mechanism to the 3 stage process by Head, 2014 (1).  Gillman and Tackley's models suggest that the thick Venusian atmospheric surface temperature provides a boundary layer for mantle convection models, in particular, the atmospheric water vapor pressure which is sensitive to volcanic activity.  They suggest that cooler surface temperatures result in a 'mobile-lid' type of tectonic regime, that is until the temperature rises again causing a return to the stagnant-lid one plate scenario that we observe today.

References

(1) Head, 2014, The geologic evolution of Venus: Insights into Earth history Geology

(2) Huang et al. 2013, Constraints of the topography, gravity and volcanism on Venusian mantle
dynamics and generation of plate tectonics, Earth and Planetary Science Letters

(3) McGovern et al. 2014, New constraints on volcano-tectonic evolution of large volcanic edifices on Venus from stereo topography–derived strain estimates Geology

(4) Azuma et al. 2014, Rheological decoupling at the Moho and implication to Venusian tectonics, Nature

(5) Turcotte, 1993, An episodic hypothesis for Venusian tectonics, Journal of Geophysical Rsearch

(6) Gillman and Tackley, 2014, Atmosphere/mantle coupling and feedbacks on Venus, Journal of Geophysical Research


Question on the derivation of a prognostic equation for the mean concentration (Assume horizontal homogeneity in X)

In the question, T was not specifically mentioned to be a constant. So by also expanding $T = \overline{T} + t’$, we end up with the following answer. Where, the covariance term containing $\overline{c’t’}$ reflects that turbulence still plays a role in determining the mean quantity of C.


How have global sedimentation rates changed over the last billion years?

Sedimentation rate presently varies many orders of magnitude depending on the place you observe. The rate of sedimentation is also different. Some places have continual sedimentation, others have episodic sedimentation events.

That is why charts that show changes in sedimentation rate are usually done for individual sedimentary basins, to determine the basin evolution. This is available for many basins, especially if they are of interest to the hydrocarbon industry.


Is there a name for a type of algorithm or processing which uses only one source of data as input?

I think you are thinking of an injective function  or mapping.
However this work you are doing sounds sort of suspect.  Usually adding additional data (with appropriate cleaning) reduces uncertainty.  If the additional data is adding to the uncertainty that might indicate that the original data set is noisy or unreliable.


I did a little poking around and came across a few projects that might be interesting.

Based on the work of Peter Bird (2003) there's a github project (fraxen/tectonicplates) that hosts georeferenced data of most major plate boundaries.

Seeing as you're interested more in minor plate dynamics, there's another project called GPlates that is an multi-OS open source visualizer for plate boundary dynamic reconstructions. While I haven't looked at the potential outputs available, I imagine you would be able to export data from this platform into a more traditional GIS data format (.shp, .gml) that could be read in GMT.


Can volcanos really change the climate so relatively (geological timescale speaking) fast, up to the abnormal levels that we are seeing today?

Even more so.

You wrote about the 1815 eruption of Mount Tambora. While that was an extremely large eruption in terms of written human history, it was rather tiny compared to the absolutely colossal volcanic events whose histories have been written in the rocks. Multiply the Tambora eruption by a factor of 10000 or more and you'll get things like the Deccan Traps and Siberian Traps.

A number of geologists think that it was the formation of the Deccan Traps rather than the Chicxulub impact event that killed the dinosaurs. A much larger fraction think the combination of the two dealt a one-two punch that ended the reign of the dinosaurs.

The Siberian Traps are still deemed by many, if not most, geologist as the leading contender for the cause of the Permian–Triassic extinction event. This was by far the most severe extinction event ever, much greater in impact than the Cretaceous–Tertiary extinction event that killed the dinosaurs. The lava released by the Siberian Traps covered an area the size of Europe (or larger, depending on who you read). It may have triggered massive fires in coal deposits, significantly adding to the greenhouse gases.

That said, what's happening to the Earth's atmosphere now is not a result of volcanic activity. It's us. (That of course is assuming that the massive amounts of hot air that comes out of the mouths of politicians is not classified as volcanic.)


Origin of Sulphuric Acid in the Atmosphere

Oxidation states of sulphur vary between -2 and +6. Sulphur compounds are generally
  emitted in reduced form. They are then oxidised in the Earth’s atmosphere, generally to
  SO2
  , a +4 oxidation state. Around 65% (the remainder is removed by dry deposition) of this
  sulphur dioxide is eventually oxidised to the +6 state of H2SO4
  , where SO2 –
  4
  is the sulphate
  ion. Sulphur is stable in the presence of oxygen in this state. The higher-state compounds
  also generally have a greater affinity to water, meaning they are more readily removed from
  the atmosphere by wet deposition.

The natural atmospheric sulphur cycle and its response to anthropogenic perturbations, Angus J. Ferraro


How to read and plot seismic waveform data in Ascii format using Obspy?

If there is no direct function available, you can create a Trace/Stream object yourself.

The solution I use (example for one time series) is:

read the Ascii file into a numpy array
trace = obspy.core.Trace(data=numpy array, header=header dictionnary of your choice)
stream = obspy.core.Stream(traces=[trace])
stream.plot()


Do high pressure systems draw air towards them?

It would be nice to have a synoptic chart relevant for the comment. My guess is that the high pressure cell was not drawing air towards itself. Instead, the location of the high pressure cell was such that it caused cooler air from the ocean to be moved towards Sydney. Fort this to happen, the high pressure cell would have been south of Sydney


Are these igneous Liesegang rings on a popular Oahu, Hawaii hike?

Not knowing the setting and judging from the image alone in this trampled environment, I think we're looking at a form of chemical weathering called "spheroidal weathering".
The gist is this (from the linked wiki page):
Penetrating water alters the bed-rock along cracks or joints, causing volume changes between altered and unaltered parts. These differences result in the formation of spheroidal layers that are removed by erosion (or trampling), leaving a central relatively unaltered boulder/pebble.
Liesegang rings are somewhat enigmatic, not sure if the term is applicable here.


What was the size of the Aral sea in year 1000 CE?

Before the 1960s, the size of the Aral Sea was relatively consistent. However, the Aral Sea went through some "dry spells" during the 1st and 3rd centuries BCE. Going even further back, the Aral Sea dried up during the Early Pleistocene and was "refilled" during the Early Holocene. In other words, the Aral Sea probably looked the same in 1000 as it did in 1950. (Encyclopædia Brittanica)


Hydrology - Depression cone VS transmissivity

Based on the Theis equation, increasing the transmissivity will increase the radius of influence and decrease the total drawdown.  Drawdown is directly proportional to the pumping rate and inversely proportional to aquifer transmissivity and storativity.

$$s = \frac{Q}{4T\pi}\int_u^\infty \frac{e^{-y}}y dy$$
and $$u = \frac{r^{2}s}{4Tt}$$
Where s is drawdown, r is radius from well, t is time, T is transmissivity, Q is pumping rate, and u is the well function.

Applying this equation, you can produce plots like this:

for these plots, I used Q = 500, S = 0.01, and t = 4


Changes in Earth's orbital and rotation speeds

The Earth moves faster around the Sun when it is near its perihelion (the closest point of its orbit to the Sun). And it moves slower when it is further away (aphelion), just as Kepler realized quite a while ago when enunciating his Third Law of Planetary Motion. There are many ways to write a formula to calculate Earth's speed around the Sun. But for your question I think this one is simple and general enough:

$$v= \sqrt{G\,M_S\left(\frac{2}{r}-\frac{1}{a}\right)}$$

Where $v$ is Earth's speed, $G$ is the gravitational constant, $M_s$ is the mass of the Sun (this equation assumes that the mass of Earth is negligible compared to the mass of the Sun, which is a very good approximation), $a$ is Earth's semi-major axis of orbit (which defines how elliptic or how circular the orbit is), and $r$ is the distance from the Earth to the Sun.

And the closest and furthest distances respectively are about 147.1 million kilometers (around January 3) and about 152.1 million kilometers (around July 4). Plugging those numbers into the equation you get a maximum speed of 30.3 km/s and a minimum of 29.3 km/s. In contrast, the speed due to Earth's rotation around its own axis, is at most (i.e. in the equator) about 0.5 km/s.

For any given day, the calculation of the distance to the Sun is complicated, but websites like this one, provide a real time value you can use in the above formula [that site also provides the speed right away!].

These values are basically the same from one year to another. However, they do slowly change as the eccentricity of Earth's orbit gradually varies over a ~400,000 years cycle as described by the Milankovitch cycles.

Now, for Earth's speed of rotation about its own axis the value is pretty much the same each day; variations are of day length are on the order of a fraction of a millisecond.  Part of that variation is periodic and more or less predictable and another part is from other less predictable factors. But for all practical purposes the length of the day is constant through the year. The following figure shows those tiny variations in day length since the early 1960's:

(image from Wikipedia commons, originally here)

But as a consequence of these tiny variations, almost every year one or two (leap seconds) are added to our clocks to keep them aligned with the rotation of the Earth. In the long run (millennia), Earth days are getting longer (~0.017 milliseconds per year).  Some of the factors involved were discussed in this question.

Finally to address whether changes in orbital speed affect rotational speed: I don't think so. For what I understand none of those small changes in the length of the day is a direct consequence of changes in the orbital speed. However, despite there is no changes in the speed of rotation, what we generally understand as a day (i.e. the time between two consecutive sunrises, sunsets or noon), is not only controlled by the rotation of the Earth around its axis. In fact, one out of the ~365 days of the year is consequence of Earth's revolution around the Sun, not its rotation. And that one-day contribution give rise to the difference between a day and a sidereal day, and the variations in the duration of the apparent solar day, variations that are directly controlled by Earth's orbital speed and can change the time between solar noon up to about 30 seconds over a year.


Had the climatologists predicted climate change as the deviations to both extremely cold and hot temperatures before?

The Intergovernmental Panel on Climate Change summarizes the state of scientific understanding of climate change every few years and at least as far back as 2002 has projected a range of changes in extreme weather.

In the IPCC report for 2002, the Working Group II: Impacts, Adaptation and Vulnerability summarized the existing scientific understanding in may areas, including "Climate Variability and Extreme Events":
"Most studies of climate change impacts have focused on changes in mean climate conditions. However, global climate change is likely to bring changes in climate variability and extreme events as well. This is relevant here because decisionmakers often consider hedging strategies to be prepared for the possibility of low-probability but high-consequence events -- a risk management framework.  Features of projected changes in extreme weather and climate events in the 21st century include more frequent heat waves, less frequent cold spells (barring so-called singular events), greater intensity of heavy rainfall events, more frequent midcontinental summer drought, greater intensity of tropical cyclones, and more intense El Nino-Southern Oscillation (ENSO) events." -
Climate Variability and Extreme Events

The question is also addressed in section 2.5. "Projected Changes in Climate Extremes could have Major Consequences":

  The vulnerability of human societies and natural systems to climate
  extremes is demonstrated by the damage, hardship, and death caused by
  events such as droughts, floods, heat waves, avalanches, and
  windstorms. While there are uncertainties attached to estimates of
  such changes, some extreme events are projected to increase in
  frequency and/or severity during the 21st century due to changes in
  the mean and/or variability of climate, so it can be expected that the
  severity of their impacts will also increase in concert with global
  warming (see Figure SPM-2). Conversely, the frequency and magnitude of
  extreme low temperature events, such as cold spells, is projected to
  decrease in the future, with both positive and negative impacts.


Continental Crust forms because of continual volcanic magma flow and pressure, erosion takes over a period of hundreds to millions of years to completely weather some object. Along with that, tectonic plates can smash into each other to form a continental crust and do land-building (The Himalayas is an exemple)

As with oceanic crust, continental crust is created by plate tectonics. At convergent plate boundaries, where tectonic plates crash into each other, continental crust is thrust up in the process of orogeny, or mountain-building. For this reason, the thickest parts of continental crust are at the world’s tallest mountain ranges. Like icebergs, the tall peaks of the Himalayas and the Andes are only part of the region’s continental crust—the crust extends unevenly below the Earth as well as soaring into the atmosphere.

“Crust” describes  the outermost shell of a terrestrial planet. Our planet’s thin, 40-kilometer (25-mile) deep crust—just 1% of Earth’s mass—contains all known life in the universe.

Earth has three layers: the crust, the mantle, and the core. The crust is made of solid rocks and minerals. Beneath the crust is the mantle, which is also mostly solid rocks and minerals, but punctuated by malleable areas of semi-solid magma. At the center of the Earth is a hot, dense metal core.

Earth’s layers constantly interact with each other, and the crust and upper portion of the mantle are part of a single geologic unit called the lithosphere. The lithosphere’s depth varies, and the Mohorovicic discontinuity (the Moho)—the boundary between the mantle and crust—does not exist at a uniform depth. Isostasy describes the physical, chemical, and mechanical differences between the mantle and crust that allow the crust to “float” on the more malleable mantle. Not all regions of Earth are balanced in isostatic equilibrium. Isostatic equilibrium depends on the density and thickness of the crust, and the dynamic forces at work in the mantle.

Just as the depth of the crust varies, so does its temperature. The upper crust withstands the ambient temperature of the atmosphere or ocean—hot in arid deserts and freezing in ocean trenches. Near the Moho, the temperature of the crust ranges from 200° Celsius (392° Fahrenheit) to 400° Celsius (752° Fahrenheit).

Crafting the Crust

Billions of years ago, the planetary blob that would become the Earth started out as a hot, viscous ball of rock. The heaviest material, mostly iron and nickel, sank to the center of the new planet and became its core. The molten material that surrounded the core was the early mantle.

Over millions of years, the mantle cooled. Water trapped inside minerals erupted with lava, a process called “outgassing.” As more water was outgassed, the mantle solidified. Materials that initially stayed in their liquid phase during this process, called “incompatible elements,” ultimately became Earth’s brittle crust.


What is the primary cause of the "Norwester" winds that affect parts of India & Bangladesh?

Though you have divided your question up into 6 parts, I am combining the information in the answer, as they all link together.  Also, as can be seen in the reference list (below), the resources come from the same primary author, but from different aspects of his studies of this phenomena (these are all paywalled, so university access would be required - but I'll paraphrase the main points).

Firstly, a bit of terminology, a Nor'wester are storm gusts between 11 ms$^{-1}$ and 42 ms$^{-1}$, above which are referred to locally as being 'tornadoes' (2).  These are collectively known as Severe Low Convective Storms (SLCS) by Yamana et al. (1),(2),(3). The main areas affected are across Bangladesh and north-east India (3).

SLCS generally seasonal, usually occurring during the pre-monsoon months of March to May, peaking in April, usually in the evenings (as you have observed). Although rare, SLCS can actually occur at any time of the day and at any time of the year (2). Records over several years do not show any particular obvious trend in occurrence and frequency of events that occur each year - though they average at around 145 occurring each year (2).

Yamane et al. 2010 (2) note that the most frequent occurrence is in the Dhaka district (north-central Bangladesh) and trends in a northerly direction during the pre-monsoon.  However, the authors caution this observation as being the result of the amount of people recording these occurrences in other districts.

Yamana and Hayashi (2006) (3) explain that the SLCS are a result of regional atmospheric thermal instability, where the convective available potential energy (CAPE) is high (greater than 2000 Jkg$^{-1}$) and the shear is moderate (greater than 10 ms$^{-1}$, and that the phenomena also coincides with severe local storms across the Indian Subcontinent.

Yamana et al. (2012) (1) elaborates further on what causes the atmospheric thermal instability, with a synoptic analysis of a SLCS, describing the phenomena as a confluence of  (note, the authors use AGL = 'above ground level' for the following information):

Moisture inflow (increase in humidity) from the Bay of Bengal, enhanced by a south-west wind intensification at 950 hPa (approx. 500 m AGL). This increases the amount of water vapour available.
A temperature increase, due to westerly winds, across the region at 800 hPa (approx. 2 km AGL), leading to
A trough leading to an enhancement of cold advection at 550 hPa (approx. 5 km AGL) from the north west.

This, in part, gives a reason for its name and confirms your 6th point, that it blows in from the north-west.

References

(1) Yamana Y. et al. 2012, Synoptic situations of severe local convective storms during the pre-monsoon season in Bangladesh, International Journal of Climatology

(2) Yamana Y. et al. 2010, Severe local convective storms in Bangladesh: Part I. Climatology, Atmospheric Research

(3) Yamana Y. and Hayashi, T. 2006, Evaluation of environmental conditions for the formation of severe local storms across the Indian subcontinent, Geophysical Research Letters


Surface temperature in early hadean period

It's a can of worms with no definitive answers, not least because, apart from a few ancient zircons, almost all the evidence has been obliterated by later processes.
Critical factors would have been the rate of crustal recycling, the rate and distribution of heat from radioactive decay, the extent and intensity of the greenhouse effect, the onset of plate tectonics, ratyes of magmatic differentiation, and the role of water in the early crust. Develop a model with your own set of assumptions - it's as likely to be as accurate as any of the multitude of models already existing.
The Hadean in total lasted about as long as the Phanerozoic, and even the early Hadean would have been not less than 100 M.a. in duration, over which time conditions changed massively.
Some temperature estimates for the Hadean include:

Early Primitive mantle, about 1650 to 1850 deg C
Mafic zircons 750 to    850 deg C
Late Hadean zircons from Jack Hills, West Australia, 700 deg C
Crustal rocks with plate tectonic under-thrusting, 600 deg C.

So my best guess for the early Hadean surface: Not far short of 2000 deg C.


Can strong winds significantly lower ocean surface levels, or is it really the static pressure differences?

The explanation for the wind effect on water level at the coast is basically the same as for upwelling circulation. In an upwelling situation, the winds flow parallel to the coast and generate upwelling dynamics: surface Ekman balance is setup (in deep enough waters) with water transport being to the right (left) of the wind in the northern (southern) hemisphere; this causes a deficit along the coast that needs a compensating flow in the deeper part of the water column bringing cold water to the surface. The deficit along the coast and the resulting sloping density levels create a geostrophic balance and that causes the surface water level to drop near the coast (wind set-down).

A good diagram of the processes at play is available from Csanady (1981).
Source: EOS

In reality, the Ekman balance-geostrophic balance combo is a better approximation when the shelf is narrow and there is a stronger connection with the open ocean. In shallower areas, the wind that matter most is not the along-shelf wind, but rather the cross-shelf wind:

Depth of the wind-induced currents and the shoreline

In the case of a hurricane, the winds and atmospheric effects are so strong that it is difficult to separate the two. The article cited in the question mentions the two effects. The fact that the wind lined up with the coastal alignment suggests that wind set-down might have been a factor. It is not that uncommon for wind set-down to be a controlling process (e.g., Red Sea (also)).

Csanady, G. T. (1981). Circulation in the coastal ocean, Part 1. Eos, Transactions American Geophysical Union, 62(2), 9-11.


Was the Earth's sea-level significantly lower in ancient times?

There are several questions here, I'm only focusing on the question regarding sea level in the past as per the title question.

In short, global mean sea level (GMSL) has been both lower and higher than present in the past. As recently as the last glacial maximum around 25,000 years ago GMSL was around 120m below present as much of the water was held on land as ice.

However, GMSL doesn't really exist because sea level is not level, but is a useful way of summarising global trends. What people living in coastal areas experience is relative sea level (RSL), which is defined as the mean level of the sea surface relative to the level of the land. There are two key components affecting RSL: isostasy and eustasy. Put simply, isostasy refers to the vertical position or motion of the land (the Earth's solid crust sits on a molten mantle and is subject to vertical displacement from its equilibrium state governed by the balance of overburden pressures  i.e. a concentration of mass on land causes subsidence of the land beneath it whilst uplifting the land extending beyond the focus of the mass. Eustasy refers to a uniform, global change in sea level caused by fluctuations in the balance between water held on land (usually as ice) and in the oceans, or by a change in the capacity of ocean basin (usually tectonically related). RSL can vary considerably from GMSL (unsurprising since this is a mean measurement). For example (I'll use a British example here since that's where I'm from), at the last glacial maximum ice sheets covered the northern part of the British Isles from Scotland down to around the middle of England  (the exact southern extent is still debated in the scientific literature). The overburden of this ice effectively turned the British Isles into a giant see-saw with the land in northern part subsiding and the southern part uplifting. The effects of this are still felt today long after the ice has melted (and contributed a eustatic sea level component) as the land level readjusts to its equilibrium state( glacio-isostatic adjustment); the land in Scotland is rising and the land in the south of England is subsiding. So, whilst is true that globally sea level is rising  (at a rate of around  3.2 mm/yr), when combined with local land level changes then some places actually currently experience a sea level fall (in Scotland this is up to -1.5mm/yr) whilst in regions of isostaic subsidence the rate of sea level rise can be considerably greater than GMSL.

Since you mentioned gravity in your question I'll breifly introduce another curious component  (there are others,see reference below) which results in globally  non-uniform sea level changes. We are not experiencing a lower level of gravity  (gravity is a constant).  The amount of gravity that something possesses is proportional to its mass and distance between it and another object. On Earth mass is obviously not evenly distributed, with each location on the planet experiencing a different mass-dependant   perturbation of the gravitational field. So for example, as an ice sheet forms and grows  mass increases which results in a gravitational perturbation which attracts the ocen toawrds the ice sheet but as the ice sheet melts and the gravitational perturbation reduces that water that was previously drawn towards the ice mass is redistributed in distant locations from the ice mass. This (counterintuitively) means that the greatest rates of sea level rise as a consequence of Greenland melt are actually experienced in the Southern Hemisphere.

Hope this serves as a useful introduction. I would usually include more references but I'm writing this on my phone right now whilst travelling on a train. One key reference,which is written in a non-technical style, worth checking out is :
Sea level is not level : The case for a new approach to predicting UK sea-level rise. / Gehrels, Willem Roland; Long, A.J.
In: Geography Compass, Vol. 93, No. 1, 01.03.2008, p. 11-16.


The inner core of the Earth is a large sphere of nickel-iron alloy. Surrounding this is the molten inner core which has a temperature of approximately 5400 ℃.

The source of heat that keeps the Earth's core hot and molten is the decay of radioactive elements, predominantly uranium, thorium and potassium.

The Mantle and Crust act as insulators for the Earth's Core.


Will kerosene reserves deplete long before oil?

No.

At the moment, we use cracking to turn heavy, long-chain hydrocarbons into more valuable short-chain hydrocarbons, such as petrol/gasoline and kerosene; as a general rule, lighter hydrocarbons are more valuable, at least up to butane.

Generally, it might take the form:

C$_{16}$H$_{34}$ $\ce{->}$ 2 C$_8$H$_{18}$  (Octane, a typical petrol component)

Note that this is not balanced; to crack to fully-saturated products we need to add hydrogen, usually made from natural gas and water. This is why you sometimes see that a refinery will take 1 tonne of heavy crude and make 1.1 tonnes of petroleum products. This is called 'refinery gain'.

Essentially, as long as we have hydrocarbon feedstocks, we can make kerosene.


The UK Government already publishes information on this at the national level, which may be a useful guide for how to proceed at the local government level.
The last UK Climate Change Risk Assessment was published in 2017 and the next one is imminent in mid-2021.  They follow risk assessment methods set out in things like the HM Treasury Green Book, which, despite the name, is not about environmental assessment specifically (there are Orange, Aqua and Magenta Books too).  The Green Book
has a shorter, climate-specific supplement that may be a good place to start.  In particular, Annex B of the supplement has lots of links to other resources and tools for doing the assessment.
There’s also a local government website that hosts a slightly random selection of plans that various regions have put together over the last few years.
This all looks like a daunting amount of paperwork to a scientist like me, so good luck!


What causes this arc in the night sky where the background is brighter on one side than the other?

What is happening here? Photoshop!

  The number of visible satellites plummets towards the middle of the night when more satellites fall into the shadow of the Earth, represented by the dark area on the left of the image. (emphasis added)


Which are the biggest methodological differences between the archaeological and geological approaches to stratigraphy?

As I see it there are no clear differences. There are, however, processes that are not compatible with a superposition principle. In geology, it is possible for layers to be folded and result in inverse age relationships. Packs of sediments can also be pushed over other layers during, for example mountain building, so that sequences are out of order or even repeated, almost like shuffling a deck of cards. It is also possible for, for example, magma to penetrate into rocks and generate much younger layers within an older rock mass. A depth, mass is added to the crust by melting and solidification while cooling such that rock units of different age can be found parallel (in a stratigraphic context) to each other. Hence the superposition principle only applies in sedimentary rocks and unconsolidated sediments that has not undergone and significant tectonic activity. But, I can also imagine that archaeological material can (although not extensively) be subject to disruptions in certain environments where active tectonics are at play or for example where glaciers act to push material forward and generate repeat sequences.

To expand on the second part of the post. Geological stratigraphy is established from physical exposures and by measuring structural shapes such as the strike and dip of strata (a branch of geology called Structural geology. Very little is gained from created exposures such as open day mines, mine shafts of other dug pits. It is also possible (as in archaeology) to use geophysical methods to infer layer by ground penetrating radar, seismics etc. It should be mentioned here that methods and possibilities vary between bedrock and unconsolidated sediments, where I would venture to say that archaeology and studies of the unconsolidated sediments are very similar using test pits and coring with the addition of understanding transport mechanisms to understand how and why certain sediment layers exist where they are.

Visualisation pof geological data is usually done in sections or logs of boireholes with attempts to connect between observed sections. In bedrock where there is not only vertical variability but also significant horizontal, such as in igneous rocks, obtaining a precise image is very difficult


Why is the mass of atmosphere of Venus so much greater than that of the Earth?

It is thought that about 4 billion years ago, Venus had an atmosphere and oceans similar to Earth's. Owing to it's proximity to the sun and the fact that most of its primeval atmosphere was carbon dioxide, it heated up and the oceans evaporated away, causing more greenhouse heating as they did so. Water vapour is a potent greenhouse gas.

Earth's primeval atmosphere was also mainly CO2, but being about 30 million miles further away from the sun it did not experience the runaway greenhouse effect which overheated Venus. The seas did not evaporate into the atmosphere, as they did on Venus, where the water mixed with sulphur dioxide/trioxide to create clouds of sulphuric acid droplets.

Another thing which has thinned the Earth's atmosphere is billions of years of sequestration by living things, which have transformed atmospheric CO2 into limestone (CaCO3), other carbonates, and various forms of fossil hydrocarbons (Lange et al., 1983). The photosynthetic organisms which produced the hydrocarbons also produced huge quantities of oxygen, which today makes up 21 percent of our atmosphere.

If you could magically turn all the carbon sequestered away in the rocks back into CO2, and evaporate our oceans so that they went up into the atmosphere, the Earth would be much more like Venus, including the runaway greenhouse effect which has heated Venus's lower atmosphere to 460C. Being much further away from the sun than Venus, Earth would not heat up as much as that, but it would still be too hot for life.

Mars also had an atmosphere similar to Earth's and Venus's, but because of its much weaker gravitational field has been unable to hang onto them. However, the proportions of the gases in the Martian atmosphere are still similar to those on Venus, though far more tenuous.

Lange, M. A. & Ahrens, T. J.(1983):"Shock-Induced CO2-PRODUCTION from Carbonates and a PROTO-CO2-ATMOSPHERE on the Earth", LUNAR AND PLANETARY SCIENCE XIV, P. 419-420.
http://adsabs.harvard.edu/full/1983LPI....14..419L


What is the tectonic explanation for parallel ridges in the Arctic Ocean?

The fact that these three features are parallel may be somewhat coincidental, although we can suspect that tectonic forces have influenced their morphology. The crust under the Arctic Sea is one of the least understood regimes in the world.

This is changing - whichever country can prove that their nation's continental shelf extends along one or more of these ridges can, according to the United Nations, claim subsurface oil and minerals.  Candidate countries include Russia, Canada, Norway, the USA, and Greenland/Denmark. As a result, there has been recent seismic and geological work in the area, though some of the reports are nuanced in an effort to bolster nationalistic claims.

Alpha Ridge is a volcanic ridge extension off the continent from
   Ellesmere Island, Canada.

Lomonosov Ridge seems to be ancient continental crust and is likely an
   extension of Canada's continental shelf.

Gakkel Ridge accompanies a spreading seafloor rift which extends north from the mid-Atlantic ridge. It has the slowest divergence of any mid-ocean ridge in the world (less than a centimeter a year).

Here is how the three ridges appear in cross-section:

   (Source: http://en.wikipedia.org/wiki/File:BrnBld_BeringToFram.svg)

There are two basins in the Arctic. The part closest to Europe, the Eurasian Basin, formed when the mid-Atlantic Ridge grew to the north, becoming the Gakkel Ridge. It divided a long, narrow strip of continental crust from the Barents Shelf, the Lomonosov Ridge. This action resulted in Lomonosov's parallel orientation to the Gakkel. Since the Alpha Ridge is further to the west and within the Amerasian Basin, it might be a stretch to suggest it is related to the Gakkel. It's parallel orientation is more likely an accident and in time it may rotate with respect to the other two ridges.

For an accessible and lucid description of the Arctic's tectonics, this piece by Bernard Coakley in the New York Times is quite good:  http://scientistatwork.blogs.nytimes.com/2011/09/15/northern-lights-on-the-midnight-watch.


How reliable is sea-ice concentration (fraction) data in ERA-Interim?

I would recommend changing from ERA-Interim to ERA-5, since ERA-Interim will be outdated soon. This is the information currently given by the data provider:

  ERA Interim is being phased out. Users are strongly advised to migrate to ERA5. The last date to be made available in ERA Interim will be 31 August 2019, which will be released at the end of October 2019.

It would still be good to solve the issue you are currently having with ERA-Interim.

  [...] some grid cells over land have sea-ice information. Not a big issue so far, because spatial discretization must always lead to some discrepancy in land-sea mask. [...]

As you mention, spatial discretization can lead to discrepancies. Do you use the land-sea mask from the data provider? If the land-sea mask is given in a fraction, you would have the possibility to put a threshold on the land-sea fraction and thereby filtering out "coastal" gridpoints. The best value for this threshold depends on your application.

  [...] But these specific grid cells, those closest to the coast (or even on land) show very weird values sometimes.

Is the dataset conforming to the CF conventions? If so, the variable considered most likely has a valid_range attribute. There are specific rules specified how software should treat the data. You should check that your software adheres to these rules. Inspecting the data with another software package can be helpful. If this does not solve the problem, I suggest contacting the data provider, since there might be a real issue with the data that they should be aware of.


Certainly there are such places. They are simply spots where the nearby rocks have a high concentration of magnetic minerals with a strong remanent magnetization. They're not necessarily literal hills: any kind of topography can be magnetized in this way. I'm not sure what exactly you mean by "drives your compass crazy" -- its direction will be affected, but it won't spin around madly since there's still a field for it to align to.

These phenomena are called magnetic anomalies, and their effect on a compass is called magnetic deviation. You can get an idea of anomalies at a large scale by looking at the World Digital Magnetic Anomaly Map -- however, this map shows anomalies as measured or inferred at 5km above sea level, so small-scale surface features won't show up well. You'll see that, in Europe, there are a lot of anomalies in north-eastern regions (corresponding to iron ore deposits, I suspect) and in Iceland (corresponding to lava flows). At the surface level, there is a fairly recent magnetic declination chart of Europe, but the spatial resolution is too low for the small, intense features which you seem to be interested in.

I think these small-scale magnetic anomalies are mainly of interest to navigators (marine ones might be marked on nautical charts -- I'm not sure) and possibly to exploration geophysicists (who might use them to infer the presence of ore bodies). Unfortunately, data collected for mineral exploration purposes tends to be kept private for commercial reasons. However, geological maps can give you some clues: volcanic rocks tend to be relatively magnetic so if they're near the surface they're good candidates. I found this paper about magnetic anomalies on Mount Etna which shows magnetic declination varying by about five degrees across different sites on the volcano.


Yes, earthshine is completely normal. It is simply illumination of that part of the moon that is facing away from the sun. This illumination is sunlight that is reflected towards the moon by the Earth. Strictly speaking, it is that reflected light from the Earth that is itself reflected back to Earth so that we can see it. The intensity of Earthshine is highly variable. If the moon was almost in line between Earth and sun then an observer on the dark side of the moon would see the the whole of Earth's disk brighly illuminated by the sun, and hence the earthshine would be about at its maximum. Conversely, when the Earth is nearly between Moon and Sun, an observer on the moon would only see a crescent Earth (apart from man-made city lights), so the Earthshine would be at a minimum.


Is Cape Canaveral really the lightning capital of the US?

It's pretty likely. Florida has the highest lightning strikes of anywhere in the US, as can by seen by this map from lightningsafety.com This is the area near Florida, with the highest levels.

It's hard to see, but the highest density is actually just to the west of the Cape, but it's not too far of a stretch to say it's the lightning capital of the US.


What is the geothermal potential of a volcano?

Volcanoes erupt due to increase in pressure, within the magma chamber (often 3-10 km deep), due to exolusion of volatiles. The magma chamber is usually heated from below. Geothermal plants in volcanic regions exploit heat from hot water in the "shallow subsurface", few hundreds of meters deep (and rarely exceeding 1-2 km). So as far as your second last question is concerned the impact on the volcano will be little as deep hydrothermal circulation can only transport so much heat.

There are many such plants around the world, e.g., Iceland, Philippines, Indonesia, New Zealand etc. However drilling in hot rocks has its own set of problems. It is also not easy to build large plants near volcanic areas due to lack of accessibility, infrastructure, market etc.


Is there a defined reference period for the COP21 agreement?

It's relative to the immediately pre-industrial years.

As per the press-release from the UNFCCC on COP21:

  The universal agreement’s main aim is to keep a global temperature rise this century well below 2 degrees Celsius and to drive efforts to limit the temperature increase even further to 1.5 degrees Celsius above pre-industrial levels.


How to remove 'silk braid' noise in satellite data?

You ask, How to remove these abnormal value for more precise data?

The short answer is that you might be able to make your data look more representative of the natural 'truth', but you will probably have to pay for this with some precision. The problem is that the measurement itself is imperfect: this looks like an artifact of the data collection method. The general name for unwanted energy that interferes with a signal you are interested in is noise.

In your case, there is some random noise, and there is this coherent (i.e. spatially organized) noise. It is likely impossible to substantially attack either type of noise without touching the signal. In other words, you will probably have to pay for the noise reduction with some loss of precision. This may be a trade-off you are willing to make.

Reducing noise

There are many, many ways to reduce noise in data. A very common way to reduce random noise is to apply a smoothing filter such as a simple mean in some small, moving window (often expressed as a convolution operation). The problem with this is that it just mixes the noise into the image.

You can also think of a smoothing high-cut filter in the spatial frequency (aka wavenumber) domain. A common approach to removing the sort of spatially organized noise you have is to use a 'notch' (narrow) cut filter in this domain, which has the effect of removing noise with that spatial frequency. In other words, you can remove stripes.

Filters that remove stripes can be found in various image processing software, or could be implemented with various scientific computing languages (e.g. MATLAB's Image Processing Toolbox or scikit-image for Python). Here are some options:

FFT in ImageJ/FIJI — I would start here, unless you're already into MATLAB or Python.
Destripe in GIMP — another good option.
Destriping in ISIS — an image processing package from USGS.


Measuring stations are used, but to fill in the gaps that are inherently there. Satellite observations of surface level temperatures are used to smooth out the data (and gather information about the oceans) to create a full look at the global temperature.
Then the observed temperatures are compared to averages from recorded history and hot and cold spots are determined. Then finally the temperature deviations are added and subtracted respectively from each other until all deviations have been accounted for and a determination of above or below average is determined.
ECMWF uses their Copernicus satellites for this type of research which is documented in this presentation. The data is available through their ERA5 database.


Is there any explanation for the large amount of sea ice around Antarctica in 2014?

Antarctic sea ice extent for April 2014 reached 9.00 million square kilometers (3.47 million square miles), the largest ice extent on record by a significant margin.

  Is there any explanation for such an extreme excess of sea ice around Antarctica recently?

I'll give four separate answers:

It's not as significant an increase as you think.
The Interdecadal Pacific Oscillation is strongly in its negative phase.
The Southern Annular Mode is at a 1000 year high.
Natural and man-made variations have collectively caused increased melting of the Antarctica ice sheet.

It's not as significant an increase as you think.

It's important to remember what that "largest ice extent on record" means. That "on record" means in the satellite era. Data from before the satellite era (pre-1981) are rather spotty. Except they aren't.

There's a nice proxy for sea ice extent, at least during Antarctic summer, in the locations at which whalers made their catches and established their factory ships (Williams 1997). In the first half of the 20th century, whalers sought species that concentrated near the edge of the Antarctic sea ice. By the early 1930s whalers had developed a practice of anchoring factory ships within 20 km of the ice edge and followed the ice southward as summer progressed. This practice continued throughout the 1930s and resumed after WWII through to the mid 1950s. The practice was later restarted in the mid to late 1970s. Every whale caught by Norwegian whalers was tagged with date, latitude, and longitude. The practice of setting up shop near the ice edge gave Williams a nice way of estimating the pre-satellite era ice extent.

What Williams found was that summer Antarctic sea ice suffered a massive decline that continued throughout the 1950s and 1960s. The ice levels we are seeing now, at least during Antarctic summer, are on par with the levels seen eighty years ago.

The Interdecadal Pacific Oscillation is strongly in its negative phase.

The Interdecadal Pacific Oscillation (IPO) is highly correlated with a hiatus in perceived global warming and also with increased precipitation in the Antarctic (Meehl 2013). An increase in precipitation means that surface waters are less salty (increasing the freezing point) and cooler. The combination of reduced sea surface temperatures and reduced salinity makes for increased ice formation during the Antarctic winter during periods when the IPO is in its negative phase.

The Southern Annular Mode is at a 1000 year high.

It has long been suspect that stronger winds are one of the causes of the increase in the Antarctic sea ice levels (Zhang 2007, Zhang 2014). Winds help create polynyas, open areas of water surrounded by ice. That open water is subject to freezing during the Antarctic winter. Not only are the winds strong now, they are stronger than they have been for at least 1000 years (Abram 2014).

Natural and man-made variations have collectively caused increased melting of the Antarctica ice sheet.

Just as increased precipitation leads to increased ice formation, so does increased melting of the continental Antarctic ice sheet. And the ice sheet is melting (Shepherd 2012, Rignot 2013). Gravity measurements from the GRACE satellites, combined with ice height measurements from ICESat collectively show that Western Antarctica and the Antarctica Peninsula are decreasing in mass, and at a significantly greater rate than the slight increase in the mass of the Eastern Antarctica ice sheet. This influx of cold, fresh water during the Antarctic summer makes for increased sea ice production during the Antarctic winter.

References

Abram, N. et al., "Evolution of the Southern Annular Mode during the past millennium," Nature Clim. Change, (2014)

Meehl, G. et al., "Externally forced and internally generated decadal climate variability associated with the interdecadal pacific oscillation,"J. Climate 26 (2013), 7298–7310.

Shepherd, A. et al., "A Reconciled Estimate of Ice-Sheet Mass Balance," Science 338.6111 (2012): 1183-1189.

Rignot, E. et al., "Ice-Shelf Melting Around Antarctica," Science 341.6143 (2013): 266-270.

William, K. "Abrupt mid-twentieth-century decline in Antarctic sea-ice extent from whaling records," Nature 389.6646 (1997): 57-60.

Zhang, J., "Increasing Antarctic sea ice under warming atmospheric and oceanic conditions," J. Climate, 20 (2007), 2515-2529.

Zhang, J., "Modeling the Impact of Wind Intensification on Antarctic Sea Ice Volume," J. Climate, 27 (2014), 202–214.


'Topography' implies variation in altitude. A flat rain forest, such as most of the Amazon basin has very little variation in altitude, and therefore doesn't constitute a topographic barrier. By contrast, the topography of the Andean mountain chain, further west, has a huge altitude variation, and hence constitutes one of the classic topographic barriers in respect of air flow, rainfall, salt balance, etc.
So any mountain range or plateau may be a topographic barrier. Forests may or may not be topographic barriers, according to whether or not they have significant topographic variation. Hence the forests of Papua New Guinea constitute a t.b., but most lowland forests do not.


The vast majority of magma never even makes it out to the surface - most is simply crystallised at depth in magma chambers which dead-end several kilometres below the surface, or are injected as dykes or sills within the host strata.

By OrbitalPete, posted on reddit.com

If magma rose up below that mound it probably got closer than several kilometres to the surface; and the theory could be tested with one drill hole. I'm assuming the mound itself is not lava as such but bedrock that's been forced up.


How would our weather change in the event of a magnetic pole shift?

Magnetic reversals are very random and unpredictable,but average about one every 260,000 years. We could have the next at any time,but as I say, they are unpredictable. So faras is known,they don't affect the weather,but they are very useful to geologists because they make tiny magnetic crystals in solidifying volcanic rock line up with the Earth's magnetic field. Thus,millions of years later, geologists can tell how the rock was lined up with the field when it was formed and can see for themselves how the alignment has changed in the intervening timespan. That gives them an insight into continental drift and other crustal movements. It is particularly useful in the study of sea floor spreading.


The Ural mountains are one of the oldest mountain ranges on Earth. They started forming about 300 Ma ago by the subduction of the oceanic crust once attached to the Kazakhstania plate under the ancient Laurussia continent. A subduction process that finished about 240 Ma ago.

The tectonic plates are far from fixed, some of them disappear over time other new ones can form, they can move, merge and split. The ones involved in the formation of the Ural mountains are not currently considered tectonic plates by themselves, they are part of the Eurasian plate now.

To understand the scale and magnitud of the changes in the tectonic configuration I strongly recommend you to carefully look at the wonderful animation produced by Christopher Scotese, as part of the PALEOMAP Project.
To find the answer to your question, I would recommend you to pay special attention starting on minute 3:10, by following the area that I've highlighted with red lines in the following screenshot of that video:

You will see that 416 Ma ago and before there was an active subduction boundary there inside the red polygon. So mountains were getting formed, the ocean in front of that boundary closed-up and disappear about ~240 Ma ago, giving the final push for the formation of a mountain range, that, if you follow it carefully, corresponds to the Ural mountains we know today.


Limitations on mineral precipitation from solution

This is really a wide open question on which books could be written. First let's stipulate that we are considering aqueous solutions rather than say magma.

In aqueous solution the solubility of a particular mineral depends on the temperature, pressure and chemical composition of the liquid. Generally as a solution would rise towards the surface of the earth the pressure and temperature drop which tends to decrease the solubility. Once the solution becomes saturated with respect to a certain mineral then it becomes thermodynamically favorable for the mineral to deposit. However it is possible for a solution to become supersaturated.

Also you have to remember that homogeneous conditions wouldn't really exist. There would be temperature and pressure differences in water flowing through a crevice. The water wouldn't flow at a constant rate over long periods of time. So the whole aspect of deposition and dissolution would be very dynamic.

It is also possible to dissolve minerals A and B, yet deposit some mineral C.

Also for minerals there are often many different crystal formations. Calcite deposits in hundreds of different types of crystals.


Why are minerals found in "large" quantities and not scattered throughout the earth as individual atoms?

First of all, Earth is not a random assortment of atoms. While it probably formed along like that in the beginning, somewhere along the way it differentiated into distinct core, mantle and crust, which are not chemically the same. That's a story for another question though, and there is an excellent answer to it on this site.

Back to your question, Why are there ore deposits?

So in addition to the Wikipedia quote given by farrenthorpe, here are some more (hopefully easily digestible) points:

Chemical elements posses differing properties. Even if you take a random mix of all elements in the periodic table, each and every one of them will have different properties.

Imagine a homogenous pile of gold and salt. Now, start pouring water over it, let it flow to a specific place and wait until the water dries and evaporates. Exploiting the different chemical properties of Au and NaCl, you've created two "ore deposits", one of gold and the other of salt. In the Earth, there are a multitude of processes resulting from all kinds of combinations of temperature, pressure, fluid chemistry, magma processes and more, that facilitate selective concentration of certain elements over other elements.

If you are interested, here are some answers regarding the deposit formation of gold and rare earth elements.


Short answer: it depends.

The usual workflow is, very roughly, something like this:

Condition all your data. Compute any 'missing' data you need or want (e.g. porosity $\phi$, lithofacies, saturation $S_\mathrm{W}$, S-wave velocity $V_\mathrm{S}$).
Inspect crossplots of relevant properties like velocity vs porosity, acoustic impedance vs elastic impedance (or maybe Poisson's ratio or ${V_\mathrm{P}}/{V_\mathrm{S}}$), and so on, colouring points by depth, $S_\mathrm{W}$ or lithofacies, say. Look for helpful discrimination.
Use judgment, research, advice, or inspiration to decide on how to use the relationships you find... perhaps you are aiming for seismic inversion, or facies prediction, or log modeling, or something else.

Before doing much else, I recommend picking up Avseth et al. (Cambridge, 2005) (and/or perhaps  Dvorkin et al., Cambridge, 2014) and reading it from cover to cover. Here are some short reviews and more details on these books. Alessandro Amato's two recent tutorials in SEG's Leading Edge will help too, especially if you're using Python. If you're in MATLAB, a lot of the code for those books, which are both by the rock physics team at Stanford, is available online.

Here are some nice $V_\mathrm{P}/V_\mathrm{S}$ vs acoustic impedance $I_\mathrm{P}$ crossplots from Amato's second tutorial to inspire you:


Why don't forest fires in Western Australia get as much attention as forest fires in the southeast of the country (including SA)?

Forest fires, and natural disasters in general, get attention when they affect people.

Bush fires outside of metropolitan Perth or far away from populated areas do not affect many people. Therefore, media attention is diverted elsewhere. This is not unique to WA: you have the same in NT, northern SA, and the west of eastern states.

This is also not unique to bush fires. Volcanoes only get media attention when they affect people: recent examples are Fuego in Guatemala or Kilauea in Hawaii. The other 50 or so active volcanoes in 2018 get close to zero media attention, because they do not affect anyone (or at least, they do not affect people that the Western media cares about).


Why does the loss of water from a felsic magma encourage crystallisation?

This answer is based on Winter's presentation for his textbook. Look up chapter 7 on his website, and start at slide 39.

First let's go through some of your statements:

  Felsic magmas crystallise in the crust, unlike mafic magmas which tend to make it to the Earth's surface

Not necessarily. It is true the upper continental crust is composed mostly of felsic intrusive magmas, everything else is not. The lower continental crust, the oceanic crust, arcs, etc., those are all mostly mafic.

  They are more viscous than mafic magmas and therefore it is mechanically harder to ascend

This only means they ascend slower than mafic magmas. Eventually it all depends on buoyancy. If they're liquid and less dense than the surrounding rocks, they go up.

  They are colder, so crystallise earlier, so travel less distance

Not necessarily. Their final crystallisation temperatures (aka "solidus") are also lower than mafic magmas. That's why they are liquid at temperatures that mafic melts would already be solid. This has little implication to the distance they travel (to a first order approximation).

  They are more hydrous than mafic magmas...

True! The reasons for why felsic magmas are (generally) more hydrous than mafic magmas are not important now.

  why does losing water encourage felsic magma to crystallise in the crust? Is it something to do with water being a network modifier?

Yes. Water, or more precisely, H2O acts as a flux: it is a chemical component that strongly lowers the melting temperatures of various materials, including rocks. It follows the basic chemical reaction of $\ce{rock + H2O = melt-with-H2O-dissolved-in-it}$.

The important part is that to allow H2O to be dissolved in the melt, you need to have some pressure. Otherwise the H2O just exsolves out and leaves the magma, similar to opening a bottle of carbonated drink (think coke). While there is pressure, the CO2 is in the drink. When you open the cap and depressurise it, the CO2 comes out of the drink.

Something similar happens in magmas. You have a felsic magma with H2O dissolved in it (otherwise it wouldn't be liquid, it would be solid) rising upwards through the crust. Because it goes up, the pressure around it goes down, causing H2O to leave the magma as bubbles of water vapour (or a supercritical fluid, depending on depth). Then, as the magma loses the flux, it solidifies before it can even reach the surface. Here's a diagram to explain this, in the albite-H2O simplified system, which is a good model for granites and felsic magmas:

At surface pressure (bottom of the diagram) albite melts at slightly above 1100 °C. In a dry system, the higher the pressure, the higher the temperature. For example, at 5 kbar (0.5 GPa) the melting point of albite goes up to 1200 °C. If you add H2O at surface pressures, it doesn't change anything because there is not enough pressure to put the H2O in the (non-existing) melt. But at higher pressure it is possible for H2O to dissolve in the melt, thus allowing the existence of melt. For example at 5 kbar the melting point of albite with more than enough (aka saturated) H2O goes down to 800 °C. That's 400 °C below the dry melting point!

So what would happen if a melt containing some H2O starts rising upwards at constant temperature? For example at point a to d in the diagram. It will lose H2O as it rises, increasing the solidus temperature. Because the magma is not hot enough to be liquid at the surface, it will freeze before that, while still at depth.


The launch was scheduled for 2017 using a DNPER launch vehicle. It seems that the contract contract between Kosmotras and Hisdesat was canceled and that resulted in an uncertain launch date. The satellite has been finished since 2013 and it has been waiting for over 3 years to be launched.

Source

The dispute between Russia and Ukraine resulted in EU imposing sanctions on Moscow. As a result, Russian President Vladimir Putin supposedly signed a secret decree halting launches of the Dnepr rocket (based on the Soviet-era R-36M missile that was made in Ukraine). It also affected the launch of several satellites of the Iridium constellation. With the Russian government withholding approval for the launch, everything felt apart and now the parent company (hisdeSAT) has to find another launch platform. The two main candidates are the Soyuz rocket from Roscosmos and the Falcon rocket from Space-X, but the cost of either alternative is much higher.


How much oil was consumed worldwide since it was started to use massively in the mid 19th century?

Cumulative world oil production at the end of 2017 was approximately 1.36 trillion barrels.


How many mines are there on Earth, and what is their output in tonnes?

You can get estimates from the USGS mineral yearbooks. For example, the entry on Australia has a data table with the amounts of mined resources. Or, the entry on copper lists both US production and international production, including numbers of people employed.

More number are available from government statistics websites, regarding employment. For example Australia and USA.

Digging through those websites will give you an order of magnitude of what to expect.