Isn't a warmer climate better for energy generation? Nowadays, everyone talks about it: climate change, and more importantly, how to stop it from happening. Although there's a lot of debate around the topic, the conscensus is that by inventing a way of generating clean energy, we can slow down (and maybe even reverse) the effects global warming has on the planet. Using energy that was created without burning millions of years worth of stored carbon, we can not only power our everyday lives, but also capture the carbon we've been blowing into our atmosphere using the energy-intensive process of carbon capture.

But there are still some problems. Currently, photovoltaic cells are pretty much useless during winter when it comes to fueling the homes of millions (at least where I live). We want to warm our homes, but there's not enough clean energy during those months, so we fall back on nuclear.

Wouldn't it therefore be better to have a small rise in global temperature? I mean, a higher temperature means you don't have to warm your home during winter (as much). During summer, you can use the extra energy generated by the photovoltaic cells to power airconditioners in order to cool buildings and (maybe) use some excess energy to stop the snowball effect that those higher temperatures would have on the climate and keep it at a constant level. Even though cooling requires more energy than heating, might it break even?

I don't have the knowledge nor the means to calculate if this is the case.

I know that climate change is a thing and that it's really, really bad. I'm not a guy that doesn't believe the effects it has on our surroundings. I just don't have the means to investigate this idea, that's why I ask you: will the rise in temperature have a positive effect on our energy production and the ability to satisfy energy demand?

The real problem, of course, is that it's not going to be limited to a small rise in temperature.

However, WRT energy generation in particular, most forms of generation become less efficient as temperature increases.  For thermoelectric generation - fossil fuel, nuclear, & geothermal - that's obvious thermodynamics.

Photovoltaic cell efficiency also decreases with increasing temperature (e.g. https://www.sciencedirect.com/science/article/pii/S1876610213000829 ).  The drop in energy production during winter is a product of factors like the shorter day and lower sun angle, not the temperature.

Unless I've missed something, that leaves just hydroelectric & wind generation.  AFAIK, they aren't directly affected by temperature.  Changes in weather patterns might produce more or less precipitation and stronger or weaker winds in any particular location, but I don't think the effects are predictable, or necessarily a net increase.

Finally, increased temperature affects the efficiency of power transmission.  Electrical resistance increases with temperature, so an increase in temperature leads to increased transmission losses, and a decrease in the effective capacity of the lines: https://iopscience.iop.org/article/10.1088/1748-9326/11/11/114008

We are going to get climate change whether we like it or not. Climate change has been happening throughout the last 4 billion years, and it is highly improbable that mankind is suddenly going to stop dead it in its tracks in the 21st century. It can't be denied that human activity is very gradually increasing the amount of CO2 in the atmosphere, but up to a point this process is self regulating. The higher the concentration of CO2, the more vigorously plants will grow and extract it again, but this self regulation could be overwhelmed if the amount of CO2 increases too rapidly. The present warming phase began 12,000 years ago, long before human activities contributed to CO2 levels, so there must have been some other cause. It isn't known for sure whether the sun's radiation is constant and never varies. We are now in an interglacial, which if we go by the geological record is due to end in about 5,000 years time, then it's back to the ice ages again. There was a 450 year Little Ice Age between about AD 1350 and AD 1810.

Higher temperatures don't necessarily mean more sunlight for your solar cells, but the prospect of serious climate warming provides an incentive to develop non-polluting sources of energy, of which fusion power is the most promising (yes, I know fusion produces small amounts of radioactive pollutants, but nothing by comparison with fission). I'm a bit puzzled by your snowball effect of higher temperatures. I would have thought a snowball effect would be more likely with lower temperatures.


Can a Humidity Differential move PM2.5 Pollution? Observations

There is a higher level of PM2.5 pollution outside of the house. Readings are in the 80-150 range due to wildfires. (PM2.5 levels determined by sensors in PurpleAir.com's sensor network)
Using a handheld air monitor that can measure PM2.5 readings were taken indoors.
Most rooms in the house are reading +/- 40, but one room read 450
smokey haze could be seen in the room during the highest readings (what alerted us to the problem)
relative humidity outside is typically low (30-40%)
the room with the high reading (450 PM2.5) has

high humidity (80-90%) to support tropical plants
windows from the 1990s (older, don't seal well)
an attic access panel that allows some air movement
no fans that would draw in air from outside or push air outside
room is long and skinny (40'x15') with windows along the long axis and has a door halfway down the 40' axis
one end has higher humidity (where the humidifier is)

putting 3 small HEPA filters in the room can reduce PM2.5 to 5 in about an hour. After about 10 hours, readings of PM2.5 are much higher 80-400
if we reduce the PM2.5 to under 10 and close the door halfway along the 40' axis of the room, the lower humidity side of the door stays free of PM2.5 whereas the PM2.5 on the higher humidity side of the door continues to increase.
there is no internal source of PM2.5 - this only started this week as smoke has blown into the area

Q: what's the likelihood that the humidity differential between indoors and outdoors is "pumping" air and effectively pulling smoke indoors?
Q. What's the likelihood of the humidity differential being able to concentrate the smoke indoors (there have been no readings outside that come close to the 450 PM2.5 that was seen indoors, could the humidity differential be "pumping" pollution indoors and concentrating it)?
Q. what else might be contributing or causing this?

Humidity or recent rain plays a huge difference in air pollution. Seattle has less air pollution, because the effect of heavy rain and water accumulating on particles 'wash" the air. In hotter, drier Los Angeles the pollution stays in the air longer because there's less moisture to weigh it down. Mold, spores, dust and allergens do thrive in humidity but those aren't Pollutants in the classical industrial sense.


Marine and freshwater geochemistry As rivers flow into the sea, rivers contain a high concentration of calcium and carbonates, and a low concentration of sodium and chlorine, and for marine water it is vice versa. How come?

The oceans are not saturated in sodium or chlorine. In fact, the chemical makeup of the oceans has remained fairly constant for hundreds of millions of years. Yet rivers and other sources continually bring sodium, chlorine, and other dissolved elements and compounds to the oceans. This means some processes must exist that remove constituent elements at more or less the same rate that the world's rivers and other sources supply these constituents.

It is true that the Earth's rivers bring substantially more calcium and carbonate ions to the oceans than they bring sodium and chlorine ions. Dissolved carbon dioxide from the atmosphere provides another source of carbonate ions. Yet the oceans are indeed substantially depleted of calcium and carbonate compared to the supply from rivers. So why is this?

The oceans are substantially saltier than are the rivers that supply the oceans. This is primarily a result of evaporation. Even with that, sodium and chlorine are but a fraction of their saturation levels in the world's oceans. This is not the case for calcium and carbonate. Carbonates in general have a low saturation level, and amongst common cations, calcium carbonate has a very low saturation level. Calcium carbonate is typically at or near the saturation level in the oceans, and oftentimes above it, particularly near the surface. This makes it very easy for calcium carbonate to come out of solution.

Because calcium and carbonate are at or above the saturation level, just about anything can cause calcium carbonate to form. The key "just about anything" process that causes calcium and carbonate to come out of solution is life.

This means that calcium and carbonate have a rather low residence time in the oceans. The processes that remove sodium and chlorine are much, much slower. The slowness by which sodium and chlorine are removed versus the rapidity by which calcium and carbonate are removed are why the oceans are "upside down" compared to rivers with regard to calcium, carbonate, sodium, and chlorine.

Rivers from land that flow into the ocean supply the oceans salts and chlorine from billions of years of weathering, minerals break down and the salts accumulate in the ocean. The oceans don't flow through land. The river water will never taste salty because the salts are released in small amounts over billions of years.


Where are the oldest igneous rocks found? I'm trying to catch up on my homework for earth science, but I'm having a difficult time searching for an answer to my question.

Zircons from Australia at 4.4Ga, and perhaps basalts from a Canadian island at 4.5Ga.

It would interest you to know the quest of Boston University geochemist Matthew Jackson, who is searching for the oldest basalt and mantle rock that exists.

His work isn't entirely agreed upon, as they are using all kinds of difficult isotopes which are a subject of controversy. Probably the most current information on early basalts are the claims and counter claims relating to Matthew Jackson in published articles, which have a lot of chemistry in them.

http://news.nationalgeographic.com/news/2010/08/100812-worlds-oldest-rocks-magma-earth-nature-science/

https://www.bu.edu/today/2012/little-rock-at-center-of-big-controversy/

https://scholar.google.fr/scholar?hl=en&as_sdt=0%2C5&q=tungsten+basalt++oldest&btnG=

"We've been looking for pieces of the mantle that might have survived the chaotic mixing and churning within the deep Earth," said Boston University geochemist Matthew Jackson.

"We found rocks that reached the surface some 62 million years ago—suggest a whole reservoir of the primordial rock could still lie somewhere beneath the Arctic"

There are moon basalts from 3.7 Ga years ago, they are a bit mysterious, and lunar plagioclase feldspar at 4.5, appear to have formed when feldspar crystallized and floated to the top of a global magma ocean that surrounded the Moon soon after it formed.

I remember watching a documentary years ago about diamonds and the places they are found in southern Africa. Apparently they are inclusions in the oldest rocks in that continent, which you could say fill up some sort of very large chimneys in younger rock, going vertically straight down.

So there you would have at least some of the oldest rocks on the planet.


Understanding the Mercator Projection To illustrate my problem, let's say I have lattitude and longitude coordinates, such as 38.871105, -77.056042.
I want to be able to calculate the new lattitude and longitude if, say, I moved 300m eastwords, or 400m northwards, in a way that google maps will like.
Now, from what I can understand, this would mean converting it from lat/long to mercator pixel coordinates, getting new mercator pixel coordinates then converting back to lat/long...

Here's what Wikipedia has to say on Google's Mercator projection:

Why do the above equations not actually take into account the longitude? And what is a? If I could understand these equations then theoretically the rest should be easy...
Thanks!
-B

The Mercator Projection has been used and it is used since the XVI century due to it maintain the course, rhumb or route. So it is useful for navigation.

As the Earth is approached by a ellipsoid, then you get the formulas that you saw on Mercator Projection. This transformation it is complicated for a ellipsoid, as the Earth curvature it is not a constant, so in the example you gave (moving 300m eastwords, or 400m northwards), you need to transform the first point from geographical coordinates to rectangular coordinates, then shift the point 300 meters east, check the correction on distance due to the different curvature on each point, apply the correction, then shift the point 400 meters northwards, check the correction, apply the correction and bring the coordinates back to geographical coordinate.

That is to much computing time and there are a lost of precision loss on the different shiftings and transformation geographical <-> rectangular coordinates. Web Mercator is just a Mercator that considers the Earth approach by an sphere, not a ellipsoid. That is much easier, needs less computation as, the curvature in a sphere is constant it is not required to consider.

Mercator projection is ok for navigation (that is what you are doing with Google Earth or Google Maps). Check this link.

Regarding the constants... a is the semi-major axis of an ellipsoid, amap is the semi-major axis on the map (as the Mercator Projection is distorting the distances, you should make a distance correction, that it is become bigger as far as you are from the Equator) e is the eccentricity of the ellipsoid.

Regarding the latitude issue... Thing a little bit on this question: In the Mercator Projection it is consider, as Earth approach a sphere and a revolution ellipsoid. Both surfaces are revolution surfaces so, there is no variation along the longitude way. That is why the longitude is not required for Y calculation.

Anyhow, is something is not clear, just let me know. Hope it helps!

The theory or purpose behind the Web Mercator projection is to project the globe into a rectangle made up of equally sized tiles at any zoom level. It's accuracy is highly suspect for calculating area's and distance; it is used because it makes it fast and easy to cache tiles to serve imagery and other basemaps. Rather than use the formula on Wikipedia i would look up EPSG:3857 (Mercator). As for using Google maps, it lets you toggle the reference system in the viewer from decimal to lat/long.


How do tropopause folds form and do they have any impact on synoptic scale weather? What is the process that creates a tropopause fold?  Do these features have any significant impact(s) on weather patterns or the atmosphere?

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

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

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

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

Cross tropopause transport seems to be the main driver : Take a look at this.


Any historical examples of destructive climate warming? Summation: Local cooling climate changes, since the last ice age seem relatively common and all seem to cause significant harm to human population. But I can't find instances of the reverse, warming climate changes that caused harm. If anything, the correlation seems reversed, warming climate change brings benefits. (Note: Droughts to not indicate warming.)

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

Details:

This one caught me by surprise. I had assumed episodes of destructive warming would be common and well documented.

I am reading
The Great Famine: Northern Europe in the Early Fourteenth Century by Medieval scholar William Chester Jordan. The book regards a massive famine that hit Western/Northern Europe 1315-1322. Until recently, the Great Famine was overshadowed by the "Great Mortality" pandemic episode of the Black Death which struck 1346–53. Computerization of period sources in the last 20 years has allowed researchers to correlate much wider patterns than in the past and the event is now know to have been much wider in area and of longer duration than realized.

Besides the scale, what makes the Great Famine possibly unique is that it was caused by three or more years of continuous rain i.e. it rained roughly 9 out of every 10 days, Spring, Summer and Fall.

The rain essentially drowned the seedlings in spring, the roots in summer, then rotted crops in the fields towards fall. In addition, the extraordinary wet conditions caused a "murine" an outbreak of diseases in almost all domestic animals but particularly cattle e.g. Hoofed animals often had their hooves (which are just giant toenails) so constantly immersed that eventually they just sloughed off. Other's died of water born illnesses.

I was intrigued by the event because I assumed before reading the book that the catastrophe must have been a localized example of the "The Big Sog" outcome predicted by some climate models in which the increase in world temperatures leads to significantly higher humidity world wide which causes incessant rain. I knew that the effected years fell into the Medieval Climate Anomaly which definitely represented a sustained warming in Europe and likely most of the Northern Hemisphere.

However, the chronicles, various accounting records and climate proxies all show a dramatic cooling, with brutal winters of intense cold, deep snows and ice packs forming on the Northern shores Europe. The overall climate/weather-patterns had shown a general but widely oscillating cooling pattern since the late-1200s. After the 1320s, Europe (at least) slipped into "The Little Ice Age".

It was this cooling that allowed the Black Death to spread by altering the way in which the Y. Pestis bacteria clump inside the fleas that carry it. The same dynamic of cooling, rain, harsh winters and plague outbreak, occurred in 542 in the Mediterranean world during when several years of cooling probably caused by a volcanic eruption, reduced harvest, drove nomads southward and nearly destroyed the Byzantine and Sasanian empires.

During the Medieval Anomaly it appears that the climate of MesoAmerica, North America west of the Sierras grew dryer with years and possibly decades of drought conditions. However, the overall temperatures seemed to have cooled.

Drought conditions can cause higher peak daytime temperatures because of the loss of cloud cover, but these peaks are offset by nighttime lows by the same mechanism, just as occurs in deserts. The actual heat content of the atmosphere, its enthalpy, which drives weather and climate, actually decreases because most of the heat is held in the atmospheric humidity and the biomass. It's easy to see how cooling can cause droughts.

I'm looking for the kind of increase in enthalpy predicted for world wide by current climate models.

If such events are unknown, that would be a separate question.

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.

I like this question as it makes you think about lots of things. Answering the question specifically gives me, based on my own somewhat incomplete knowledge of human history, the answer: Not really, no specific examples of human catastrophe from warming.

So now we wonder why.Clearly the concept of an average global temperature (as used in discussing climate change) is a mathematical construct and does not represent a temperature where all people live , to be crude about it. The earth has poles (very cold) and equator (very hot). Humans tend to live in the bits in between. If climate changed gradually we would expect humans to move gradually further north or further south if it started to become uncomfortable or difficult. However we know from personal experience that we go on holiday where it is hotter, often much hotter, and cope very well for a fortnight even for a temperature increase of 20 degrees C. When it get really cold however, say in a harsh winter in England, and the temperature is sub zero, maybe -15 degress C, for a few days we find it much harder to cope.

Maybe if we plot a graph of "human copeability"  v local environment temperature change it will be nowhere near linear. The other factor that comes to  mind is that cooling produces ice and snow which are physical things you need to deal with, e.g. effect on transport and also can be a tipping point for certain crops e.g. frost damage. So just a few unusually cold days/nights could destroy a crop wheras it takes a more prolonged excess of heat to damage crops, again probably a non linear graph.

Overall I expect we may find human populations that live in the colder parts of the planet are living much nearer to the "edge" of survivabilty compared to those living in the hottest parts of the planet. I seem to remember reading somewhere that humans originated in Africa (a hot bit) so our "design" is for near equator temperatures +- (some range).


High albedo vs low albedo Albedo is a measure of the amount of light reflected back by an object that is incident on it.

So, high albedo means that a greater portion of light falling on something is reflected back. This also means a that greater amount of light goes back towards outer space which is then absorbed by the greenhouse gases present in the atmosphere. Thus high albedo contributes to global warming.

Now, if we consider low albedo, then that means a greater portion of light is absorbed thus raising the temperature or otherwise the heat content of the body. Less light is reflected back for greenhouse gases to capture. But then absorbed heat itself contributes towards global warming.

So as I understand, both low and high albedo contribute towards global warming. Is this understanding of mine correct?

When we do climate change engineering, what do we try to do in terms of albedo? Do we try to achieve high albedo or low albedo?

Additionally I want to know about the effect of 'concrete jungles' in urban areas on global warming?

tl,dr: low albedo = warming (more energy absorbed); high albedo = cooling (more energy reflected).

In principle, and grossly simplifying, energy from the sun warms the ground and less the air. The overlying air is then warmed by the ground, leading to convection, pressure differences, and all that.

So, a high albedo atmosphere would prevent sunlight from reaching the ground, having a cooling effect. Equally, a high albedo ground would reflect more sunlight, less warming the air. That's why glaciers or pole caps of ice have a feedback effect on cooling.

Furthermore, wavelengths reflected by clouds can help cooling an area by day, but also trap warmth radiating from the ground when they move over it. That depends on the situation.

A low albedo atmosphere would let more sunlight pass. In conjunction with a low albedo ground it has a warming effect. Again a potential feedback when ice starts to melt and exposes more ground, leading to more warming, etc.

An open sky will allow warming of the ground by day, but also partly cools back to space by night (continental or desert climate). Greenhouse gases are those that reflect this emitted radiation back instead of letting it escape into space.

Highly populated areas can have a "heat island effect", because of the low albedo of asphalt and concrete and the lack of plants and foliage to absorb sunlight for photosynthesis and evaporate ground water and thus cool.

That (highly controversial and IMO only driven by economic interest) geoengineering thing is about raising the albedo of the stratosphere in order to reflect more sunlight before it reaches the ground. Its adverse effects on ocean acidification and damage to marine life and terrestrial plants and animals ("acid rain") and unresolved side effects could outweigh the potential benefits. But that is a discussion on its own, IMO.

Hope that helps.

No, it is low albedo which contributes to global warming because ground with low albedo absorbs more of the sun's rays. High albedo reflects them back into space, and therefore has a cooling effect. When the polar caps increase in size, this can lead to an ice age if the caps reflect enough heat into space. There can be a feedback effect whereby the more the caps reflect the heat away, the more cold it gets and the more the caps increase in size, reflecting even more heat back into space.

To change the earth's albedo artificially by a significant amount is an impossible task, and any attempt to do so would be prohibitively expensive as well as having the environmentalists up in arms. Whatever the solution to global warming, it isn't geo-engineering of the kind you suggest.

The concrete canyons that you mention would be much the same as natural canyons except for one thing: they consume an enormous amount of energy, much of it derived from fossil fuels, so make a contribution to global warming.


What is the connection (if any) between jarosite and subsoil biological activity near Spain's Río Tinto? In the short BBC video Spain's otherworldly red river, Ricardo Amils, a researcher in Spain's Astrobiology Center says the following (amateur transcription):

Río Tinto is a peculiar place in our planet that has many similarities with Mars. The most important one is iron. Mars is red because of its iron, and Río Tinto is the red river.
The river’s singular red colour comes from ferric ion, iron oxidised due to the river’s acidity...
Considering the similar geochemistry and minerology, this place is a good analogue to Mars. Life on Mars would probably look like life here.
During his trips to South America, Charles Darwin found life in extreme saline conditions. He then predicted that we would find life in the subsoil. It took us 200 years to prove him right.  If there is life on Mars, as some of us believe, it has to be in the subsoil.
What definitely equialised Río Tinto and Mars was the discovery of jarosite in Mars. This iron and potassium sulphate is produced in great quantities in Río Tinto.
Upon drilling the river’s subsoil, scientists found a great variety of bacteria and microorganisms. These could thrive in extreme conditions, and need no oxygen.

Question: Is it possible to better explain the connection (if any) between jarosite and subsoil biological activity that's hinted at by the video?

The BBC's news videos don't always remain viewable indefinitely, so here are some screen shots for background and context. click for full size

From what I've read so far, it appears jarosite may not be a prerequisite for the formation of certain life forms, instead that it is produced by certain organisms.

  Río Tinto (Huelva, southwestern Spain) is an extreme environment with a remarkably constant acidic pH and a high concentration of heavy metals, conditions generated by the metabolic activity of chemolithotrophic microorganisms thriving in the rich complex sulfides of the Iberian Pyrite Belt (IPB). Fungal strains isolated from the Tinto basin were characterized morphologically and phylogenetically. The strain identified as Purpureocillium lilacinum specifically induced the formation of a yellow-ocher precipitate, identified as hydronium-jarosite, an iron sulfate mineral which appears in abundance on the banks of Río Tinto. The biomineral was characterized by X-ray diffraction (XRD) and its formation was observed with high-resolution transmission electron microscopy (TEM) and scanning electron microscopy (SEM) coupled to energy-dispersive X-ray spectroscopy (EDX) microanalysis. Jarosite began to nucleate on the fungal cell wall, associated to the EPS, due to a local increase in the Fe(3+) /Fe(2+) ratio which generated supersaturation. Its formation has been also observed in non-viable cells, although with much less efficiency. The occurrence of P. lilacinum in an ecosystem with high concentrations of ferric iron and sulfates such as Río Tinto suggests that it could participate in the process of jarosite precipitation, helping to shape and control the geochemical properties of this environment.

Another reference, states that

  But there is something else about jarosite that makes it interesting. One of the steps in its formation involves combining pyrite (ferrous sulfide) with oxygen. This oxidation reaction can be performed by certain "rock-eating" microorganisms.

  ... And yet, there remains the tantalizing possibility that martian jarosite owes its existence to the martian version of rock-eating microbes. If so, remnants of these organisms may be locked in the mineral.

  ... This is because jarosite on Earth is known to let all sorts of foreign elements incorporate into its crystal structure.

including,

  amino acids, the basic components of proteins

Fate of Lipid Biosignatures in a Mars-Analogue Sulfur Stream

Formation of Rubidium Jarosite During the Microbiological Oxidation of Ferrous Iron at Room Temperature

Jarosite is formed from iron ore deposits by the oxidation of iron sulphides. It has nothing to do with the presence of life, but it forms an extreme environment that can only be tolerated by extremophiles. That is the only connection jarosite has with biological activity. The discovery of jarosite on Mars does not mean that there are likely to be microbes of any kind associated with it.

Extremophiles are microbes which enjoy extreme environments: extremely cold, extremely hot, extremely acid, extremely salty, extremely radioactive and so on. Most of them don't need oxygen and many metabolise sulphur to make a living. Some like the dark ocean depths and pressures in the vicinity of black smokers (deep sea fumaroles).

Some extremophiles are methanogens, that is to say their metabolism generates methane, which is why the detection of short-lived methane emissions on Mars attracted a lot of interest. A common methanogen on Earth lives in anoxic marshes, usually in woodland, where it generates marsh gas (methane). Microbes are ubiquitous on Earth, you can't get away from them. They are even found in rocks hundreds of metres below the surface.

Today you can't really find Mars-like conditions on Earth. The two atmospheres are very different in composition, the pressure is very different, average temperatures on Mars are far colder, but four billion years ago Earth and Mars were very similar. Both had seas, a dense atmosphere composed mainly of CO2, and Mars was a lot warmer, but we don't know for sure whether life was spontaneously generated there as it was here on Earth. Probably it wasn't.

These Earth-like conditions on Mars vanished within a billion years or so, and any possibility of spontaneous generation of life from inert materials vanished with them. Meanwhile Earth's atmosphere has been greatly modified by biological activity, while that of Mars has stayed much the same except for a reduction in pressure caused by losses into space and the freezing out of some CO2 at the poles, mainly the south pole.


Does volcanic activity fluctuate? According to this person's surmises, volcanic activity appers to be increasing.
However, according to this report, volcanic activity is probably not increasing.
My question is:
Does Volcanic activity fluctuate?
If it does, what would cause this fluctuation in volcanic activity?

Image cited by both:

Image: Smithsonian National Museum of Natural History, Global Volcanism Program

Is this fluctuation or recording increase?

This is probably an observational effect that is quite common in the Earth Sciences. In scientifically progressing societies there is a higher proportion of observations due to a number of effects:

awareness of science (not interpreting it as a wonder)
ability to record events
ability to observe (think 12 hour day in the factory vs. free weekend)
technology to do remote observations
...

This is also why more and more meteorites are observed falling. In the middle ages you were either too busy to care, took it as a wonder, or found a meteorite, but had no ability to write it down. Similar scenario for volcanic eruptions. I could imagine that actually all those ships, airplanes, and oudoor-activities (no offense) lead to more observations of eruptions, but that people were to busy recording and writing them down. The geologists of their time were probably busy finding war-necessary resources.

Sources:

http://www.volcanodiscovery.com/de/volcanoes/faq/is-volcanic-activity-increasing.html

An interesting observation:

When I look at the series of craters which mark the procession of various hotspots, such as yellowstone, their size and output does appear to be increasing.  Same with hawaii and madagascar (if you ignore the deccan traps.).  Although that might just be because of erosion, i donno.


How would an icicle "grow" upwards? The other day a friend of my dad's showed him a picture of an icicle that appeared to be "growing" upwards out of a crack in a sidewalk. There were no roofs, overhangs or vehicles parked near by... It looked like a stalagmite you would see in a cave. It looked something like this*:

.

How could this happen?

* Note that this is not the actual icicle, I used this picture for an example.

If there is enough water underground, in a sealed reservoir (like under the concrete in the picture), as that water freezes, it will expand, putting pressure on what ever water is left unfrozen. That water will be squeezed out through what ever cracks it can find - in this case, upwards. Because the water is already near-freezing (perhaps even slightly below, if it's super cooled), it will freeze very quickly when it hits the air (which will be much colder than the ground, late at night). But if there is still water being pushed up from below, that ice will have to move out of the way (it's weaker than concrete). The friction of the flow of cool upwards might warm it just enough to keep it liquid, and the "stalagmite" will end up with a hollow core that the water is being pumped through, and that structure can just keep building on itself, until it is toppled by wind or gravity.

The picture is a bit grainy, but it looks like that's what's happened there. It also looks like the side of the hollow "stalagmite" has fallen off up the top, and released a bit of the remaining water (or maybe it just melted in the sun).

Edit: Hah, I knew I'd seen this somewhere before - in my freezer! This page describes how Ice spikes form - I basically got it right. It seems that they're more likely to form with de-mineralised water, and the temperature has to be within certain narrow limits.

It's called an ice spike. Not fully understood, can form on any surface of frozen water. my curiosity was peaked when one formed in a cup of water in my car. Scientists can't really say why it happens yet.


Is it possible to determine where gold might be found based on a map, and if so, how? Is it possible to locate potential gold deposits using maps that describe dominant rock type, altitude, vegetation, or geological formations?

(I realize that the location would probably still have to be verified by traveling to the actual site. I am only looking for information that serves as an indicator of potential gold reserves.)

For the sake of this question I am assuming of course that these maps would not directly list gold deposits or existing or past gold mining operations.

What kind of information would a map need to contain in order to derive an indication of gold deposits from it?

On of the issues with geological maps is they have all required humans to walk over the ground and mark on a piece of paper the surface expressions of different types of rock and geological structures, such as faults and folds.

Because of this process and the time constraints placed on people when they mapped the land there will always be some level of detail missing.

Geological maps will show the different rock types and geological structures on the surface but they may not necessarily show what is at depth.

Geology has advanced to a state where most well trained geologist will know the potential for certain rock types to host certain type of mineral deposits, including gold. However, pinpointing where a gold deposit, or any other mineral deposit is located will always require a human to walk the ground and inspect it in more detail and to take samples and have them analyzed in a laboratory.

Initially those samples may be geochemical samples, others will be rock samples and chips taken from the surface or trenches dug into the surface, culminating in drill samples being taken.

To further assist where to look, geophysical testing methods may be used, such a magnetic anomaly testing or ground electrical resistivity testing.

It is very unlikely that anyone will be able to look at a geological map, and with any degree of certainty say "there is a gold deposit" or "there is a gold deposit that is economic to mine". More likely, a person will look at a geological map and say something like, "there is a greenstone belt, this may have potential to host a gold deposit, further investigation is needed".

There is an adage amongst some geologists that states "gold is where you find it". There is no altitude preferable for finding gold deposits. It's found in mountains, in deserts, in forests, under salt lakes, even dissolved in the oceans. The oceans contain the largest quantities of gold, but it is uneconomic to extract it from sea water because the concentration are so low.

Biological indicators, such a vegetation may work for some base metals, such as copper, but not necessarily for gold.

Also, gold can occur as a deposit of just gold, but it can also occur in association with other metals in the form of polymetallic deposits which contain gold, silver, copper, lead or zinc, even uranium.

Finally, not all deposits of minerals, gold included, are reserves. To be classified as a reserve and an orebody, a deposit of mineralization must be economic to mine.

Most of the most productive gold mines are in locations where the mineral was brought up from deeper in the earth in extinct volcanic shafts and magma plumes.  Gold is a heavy metal so when the earth was first formed and was much hotter and many of the elements and compounds that are now solid were in hot molten form.

At this early stage, it makes sense that the heavier and denser elements and compounds would have sunk deeper into the earth and lighter ones to float to the surface. If you pour oil into the water, the oil is less dense and floats to the surface.  The same principle applies.  Gravity pulls the denser material down closer to the center of the earth.

And that is what we see when we do seismic sonograms, and other analysis methods to reveal the earth's composition.  Silicon has an atomic weight of 28 and is thus a lighter element so it is found in abundance in almost all surface rocks and sands in the earth's crust.

As we go deeper the composition shifts to heavier and heavier elements.  The earth's core is mainly iron.  Since gold is even denser and heavier than iron it should be found in much more abundance relatively speaking at earth's core than at the surface.

We must emphasize that gold is a rare element in the earth and the universe in general for the following reasons.

All elements other than Hydrogen and Helium and counting up in atomic number to iron are formed from the nuclear fusion in stars.  All elements heavier the iron, gold among them, can only be formed in the supernova explosion that occurs at the end of a massive star's life.
Gold is not at any end of any radioactive decay chain from heavier unstable element radioactive isotopes. Uranium 238 will decay over billions of years into lead and some other elements but never into gold.

So gold, platinum, and other similar elements are rare because they are only formed in supernova explosions and no other process.

Getting back to answer your question, the only way to bring up the heavier and denser elements like gold back up to the earth's crust is through volcanic eruptions and magma plumes rising up from the interior.

Therefore, your best bet would be to investigate the igneous rocks in volcanic shafts, former eruptions, magma plumes, etc.  The other surface characteristics you mentioned like surface vegetation are irrelevant.


Would there still be wind if Earth had no water? If there was no water on the earth would there still be wind? If the planet was basically a desert from pole to pole, east to west, would the wind still blow? I understand that wind is a result of a difference in pressure, but is it true that water being naturally cooler is what creates that pressure difference?

I don't find any answers that clearly state whether or not wind would still exist without water and whether or not water is the originating source of wind. I see that most of the answers that talk about the source of wind say that cooler air moves in as warmer air rises, but wouldn't all the air in the world be warm/hot without water to cool it?  The pressure difference seems to be cool versus warm.

I wouldn't say water is naturally cooler than air.  What I would say is that water has a higher heat capacity than air.  This means it takes more energy to affect the same increase in temperature and conversely it takes water longer to cool down than air.  You can see this at night near bodies of water when the sea breeze changes to a land breeze as the land becomes cooler than the water - water temperatures tend to be stable across diurnal cycles.

I would also contest the statement that water cools the air.  Water does both heating and cooling.  When water evaporates into air, the air cools.  However take a look at any thunderstorm you see -- that is water causing heating as it condenses and freezes.  Water on the surface can also contribute to both heating and cooling.  During the day the cool water surface will have a heat flux that cools the air while at night the opposite may be true.  This depends on the air temperature and the SST.

Now on to your question, yes, there would still be wind if there were no water.  The energy that drives the wind is differential solar heating at the earths surface.  Variations in the surface topography and the shape of the earth mean that the solar flux isn't constant across the earth.  As long as we have a sun we will have surface pressure differences and wind.  Without water we would also see a stronger equator-to-pole temperature gradient (look at temperature variations right now on continents versus open ocean).  This would result in stronger winds that we see today.

If the world was uniform but still spinning, the difference between night and day would be enough to create a wind. Add mountains etc, plenty of temperature differences to create wind.


Why is this "independently reproducible proof of non-curvature" wrong? I'm currently having a (possibly useless) argument with somebody over the internet who is adamantly claiming that the Earth is flat. I know that this person could just be pulling my leg or trying to get a rise out of me but I'm still taking the challenge.

They are using this image in response to almost any argument.

What is this document even 'proving' and why is it wrong (or misleading)?

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

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

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

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

Alternative earth models and their origins are awesome to review.
The ignorant adherence to the flat earth model in the 21st century is sad. Looking at the material cited for the 'Bedford Level experiment' it's clear to me that those still using Rowbotham's formula have another fundamental problem aside from refraction distortion.

You cannot site 8 inches per mile squared if the observer and target(ways off in water) have a positive y-axis value relative to sea level. Somebody using this formula without getting their eye wet is wasting their time! Learn to solve for the height of a curve, anything inside the peak height of an arc equal to the height of the observer will be visible provided conditions are clear and one looks down about .025 degrees from their 0• level visual field.


What does "glacier collapse" mean? CNN's Mont Blanc glacier could collapse at any moment, Italy warns says:

A staggering 250,000 cubic meters (8.8 million cubic feet) of ice could break away from the Planpincieux glacier on the Grandes Jorasses mountain in the Mont Blanc massif, experts at the Valle d'Aosta regional government and the Fondazione Montagna Sicura (Safe Mountain Foundation) reported in an analysis published this week.
While it's impossible to predict the exact timing of the collapse, observations in August and September showed that the glacier was shifting at a speed of 50 to 60 centimeters (20 to 24 inches) a day, experts said.
"These phenomena once again show that the mountain is going through a phase of strong change due to climatic factors, therefore it is particularly vulnerable," Stefano Miserocchi, mayor of nearby Courmayeur, said in a statement. "In this case, it's a temperate glacier particularly sensitive to high temperatures."As a precautionary measure, Miserocchi ordered the closure of roads in the Val Ferret valley and the evacuation of mountain huts in the Rochefort area.

The caption of the image in the link (shown below) is labeled Figure 22, so presumably it's from some much larger report.
I'm curious about the choice of the word "collapse". What is it exactly that the glacier might do? Will it collapse in the same way that a Soufflé collapses, or is this more like an avalanche, or does the whole glacier just start sliding much faster, like several meters per day instead of several tens of centimeters currently?

The word collapse is not appropriate in the case of a hanging glacier such as the one you mention in your question. A hanging glacier is a glacier that terminates at a cliff edge. Since glacier ice is constantly moving towards the cliff, the terminus will occasionally lose sufficient support and detach from the glacier causing an ice avalanche. As long as the glacier feeds ice to the cliff edge ice avalanches will continue to occur. How often will largely depend on the ice velocity moving ice towards the cliff edge. This is thus a natural behaviour and not a collapse, or at least not named collapse in glaciology.
The word collapse is not a scientific term and does not have a unique definition in glaciology. In the case of an ice shelf that suddenly breaks apart such as the Larsen B (Rott et al. 1996) the term collapse has been used in articles. In this case the event was sudden and the entire ice shelf broke up and was lost during a few months. At the same time collapse is commonly used to describe other phenomena such as the loss of an ice sheet or part of an ice sheet (for example, Brendryen et al., 2020). Such a process is much slower than the ice shelf collapse, perhaps lasting many hundreds or thousands of years. But the word is used because it describes an irreversible event or development.
So coming back to the hanging glacier, its avalanches is an ongoing process and the word collapse gives the wrong impression. The glacier is not collapsing. Given climate warming the glacier will likely decrease in size and the avalanching change, possibly stop depending on the bedrock morphology on which the glacier sits. If the climate warming causes the glacier to completely melt away, then that could be considered a collapse of that glacier. But when you read different scientific articles on glaciers you will see the word used in many different ways so a tricky word to use in a good and consistent way.
References
Helmut Rott, Pedro Skvarca, Thomas Nagler, 1996 Rapid Collapse of Northern Larsen Ice Shelf, Antarctica. Science, 271 (5250) 788-792
Brendryen, J., Haflidason, H., Yokoyama, Y. et al. 2020 Eurasian Ice Sheet collapse was a major source of Meltwater Pulse 1A 14,600 years ago. Nat. Geosci. 13, 363–368.

It means that large parts might break off and cause an ice avalanche or series of avalanches which would go crashing down the valley, killing or destroying anything which got in its way.


Will the Mini Ice Age solve our Global Warming Heat problem There is news on the web saying that there will be Mini Ice Age in couple of decades.
The question is: Will this Mini Ice Age take away all the excessive heat and prevent Global Warming?

I'm going to try to answer this, though it's actually a very hard question depending on how close you look at it.

Lets start with the American Physical Society's statement on climate change - which, they've made an effort to balance out following their 2007 statement of "evidence is incontrovertible" that got some members upset and lead to a handful of high profile resignations.    More on that here

This is their more balanced statement.

http://www.aps.org/policy/reports/popa-reports/energy/climate.cfm

  The relationships between the atmospheric concentration of greenhouse
  gases and their radiative effects are well quantified. Forcing from
  the long-lived greenhouse gases: carbon dioxide, methane, and nitrous
  oxide, is presently about 2.5 Watts per meter squared (W/m2). Of this
  total, 1.6 W/m2 is from carbon dioxide alone. The total anthropogenic
  forcing is uncertain, particularly because the magnitude of the
  negative forcing associated with sulfate aerosols is unclear. While
  changes in solar irradiance may have affected global climate in the
  last century, a 0.15% change irradiance, the order of estimated
  changes, results in only a 0.36 W/m2 forcing.

and, numbers vary, but this seemed a pretty fair article on Solar Irradiance:   http://earthobservatory.nasa.gov/Features/SORCE/sorce_03.php

It says:

  The number of sunspots visible from the Earth not only changes from
  day to day, but also in cycles that can last from decades to centuries
  to millennia. The most well-known and well-analyzed of these cycles is
  the 11-year sunspot cycle. Over the course of 11 years, the yearly
  average number of sunspots and faculae slowly increases and then
  return to normal levels before rising again for the subsequent cycle.
  The change in the Sun’s yearly average total irradiance during an
  11-year cycle is on the order of 0.1 percent or 1.4 watts per square
  meter.

So, 1.6 watts per square meter from Co2 (2.5 watts total) and (up to) 1.4 watts per square meter low to peak solar irradiance, but there's a problem with that 1.4 number.    It's low to high, meaning low to average is 0.7 watts per square meter and that's how we should measure assuming the sun enters a grand minimum, we should measure against the average, so the real number is 0.7 watts per square meter drop - assuming the study is right and the sun does enter a new Maunder Minimum.

Skeptical Science posts a similar number:

Source:  https://www.skepticalscience.com/solar-activity-sunspots-global-warming.htm

The variation in their chart appears to be similar to the 0.7 variation we should expect from the NASA article, average to low range.

There's also the, all but guarantee that CO2 will continue to rise, at least, for several more years, so the APS estimate is likely to go up.   Also, the APS number doesn't include feedback mechanisms - and they say as much in the article linked above:

  The largest source of uncertainty lies in determining the magnitude of
  climate feedbacks. For example, an increase in trapped radiation and
  the associated warming is expected to increase the level of water
  vapor in the atmosphere, which would tend to further enhance the
  greenhouse effect ó a positive feedback. An example of a negative
  feedback would be an increase in clouds that reflected more sunlight
  back into space. The actual feedback from changes in clouds is
  uncertain since they also act to trap outgoing infrared radiation.

Now, the positive feedback from water vapor is a given and the negative feedback from clouds is more uncertain, so I think the APS article is a little bit more friendly to the skeptics than the actual science (IMHO).  Clouds reflect sunlight, but clouds also trap heat at night.  The total cloud effect is, well, a little more cloudy than APS' one line suggests.

Skeptical Science has an article on cloud feedback here:  http://www.skepticalscience.com/clouds-negative-feedback.htm

So, where does that leave us:

Well, first, the study that the sun is going to enter a grand minimum in the next few decades needs to be verified, lets start there.   A whole bunch of bad science has been published by those trying to disprove, discredit or cast doubt on climate change - so skeptisism of new studies first, especially on this topic, but, lets say they're right - which was the original question.   Would that be sufficient to stop man made global warming?

No.   I think it's pretty likely it would be insufficient.   0.7 is less than 2.5.   But, if they're right, it's still kind of good news, cause it would soften the blow - and that's a good thing.   I hope they are right.   But the sun's maximums and minimums have a pretty small effect on climate change.  Maybe a degree here or there.   Man made climate change should be 2 degrees by the end of the century, and perhaps more if left unaddressed in centuries that follow.

As Steve Emmerson points out, the effect of the Maunder Minimum isn't 100% accepted as the sole cause of the Mini ice age.   There's still some unknowns, but I feel, with pretty high confidence, that the sun entering a new grand minimum would be insufficient to stop the warming, but it might slow it down, a little.

Too long?   I can try to clean it up a bit later.

It may solve the heat problem but unlikely to solve the flood problem, and might create the cold problem in the North Atlantic.


At least by theoretical biology - could there be, or should there have been, or was a "southern Taiga" on earth? All data I have ever encountered about the Taiga "pole surrounding", vast, cold forests comprised mainly of Pinophyta trees, was about the northern pole surrounding forests ranging from northern Scandinavia and northern European Russia to northern Siberia and northern Canada.

Considering woodland of areas a little bit close to the southern pole, south Patagonia (extreme south of south america) reminds me a bit of the northern forests; the vegetation at and New Zealand and in Norfolk island (which might be mostly artificial in that island) a bit too, and perhaps paleoentological findings about trees in Antarctica in the past will even more resemble a "Taiga".

At least by theoretical biology - could there be, or should there have been, or was a "southern Taiga" on earth?

I'll define a boreal forest as a place that

Has trees, i.e., long-lived woody plants that are capable of growing at least ten meters tall and that grow both upward by extending new branches and outward by widening of the trunk. Amongst other things, this rules out times before ~380 million years ago, which was when the first trees formed.
Has sufficient trees so as to constitute a forest, which I'll define as a largish area where trees grow sufficiently dense so as to form a more or less closed canopy. This distinguishes forests from areas with only  a few trees such as savannas and krummholz.
Has very harsh winters, with at least one month where the average temperature is well below freezing, and temperatures of -40° C are not rare. This distinguishes boreal forests from cold oceanic forests such as the Magellanic subpolar forests in southern Chile and Argentina.
Has mild summers, with only a few months where the average temperature exceeds 10° C. This distinguishes boreal forests from hemiboreal and temperate forests. Note that some scientists do not make this distinction, classifying Köppen climate zone Dfb as boreal.
Is extensive. This distinguishes large boreal forests from high altitude subalpine forests that would locally pass the above tests. Subalpine forests can occur at any latitude, including Australia's Snow Mountains, New Zealand's Southern Alps, and parts of the Andes.  This is not a clear-cut boundary. As a climate cools, subalpine forests may spread to the valleys between mountains and then spread out beyond the mountains. At some point, such montane forests becomes boreal forests.

The need for very harsh winters coupled with the need for extensiveness means that boreal forests did not exist between the start of the Triassic ~252 million years ago to the end of the Eocene ~34 million years ago. The Earth was in its greenhouse phase during that long stretch of time, with balmy temperatures year round even at the poles. A boreal forest can only exist when the Earth is in its icehouse phase. This includes the last 34 million years, and also the period between 340 to 250, the late Paleozoic glaciation. Unlike the current ice age, the Earth in the late Paleozoic had land (Gondwana) surrounding the South Pole.

The question then is whether either of those intervals (the last ~34 million years, and the late Paleozoic glaciation) have supported a southern boreal forest. Per Rees-Owens et al., the answer is a possible yes to the more recent interval. Forests existed on Antarctica until as recently as 2.5 million years ago. Whether these were Köppen climate zone Cfc (subpolar) or Dfc (continental boreal) is very hard to say. If one relaxes the requirement for cold winters a bit, then those recent forests almost certainly were boreal.

Per Horton, et al., and also per the authors of several related papers, the answer is an unequivocal yes to the more ancient interval. Moreover, the boreal forest of that ancient time would have been very much like the boreal forest of present time: One of the largest ecozones on the planet.

References:

Horton, D.E., Poulsen, C.J. and Pollard, D., 2010. Influence of high-latitude vegetation feedbacks on late Palaeozoic glacial cycles. Nature Geoscience, 3(8), p.572.

Pross, J., Contreras, L., Bijl, P.K., Greenwood, D.R., Bohaty, S.M., Schouten, S., Bendle, J.A., Röhl, U., Tauxe, L., Raine, J.I. and Huck, C.E., 2012. Persistent near-tropical warmth on the Antarctic continent during the early Eocene epoch. Nature, 488(7409), p.73.

Rees-Owen, R.L., Gill, F.L., Newton, R.J., Ivanović, R.F., Francis, J.E., Riding, J.B., Vane, C.H. and dos Santos, R.A.L., 2018. The last forests on Antarctica: Reconstructing flora and temperature from the Neogene Sirius Group, Transantarctic Mountains. Organic Geochemistry, 118, pp.4-14.

There was a sort of southern taiga on the northern fringes of Antarctica about 40 million years ago in the early tertiary, but this was probably killed off by the increasingly cold weather some ten million years later. The taiga as we know it today is in the northern hemisphere and is composed mainly of conifers (taiga is a Russian word), but you wouldn't expect a taiga in the antipodes to be of the same species as in the northern hemisphere, or for there to be a Russian word for it. There were no contemporary Russians.

The southern taiga was composed of nothofagus trees, a hardy broadleaf also known as southern beech, and there is a relict population remaining in a ring extending from extreme S.America, S.Australia, and New Zealand. In the late cretaceous these continents were linked to Antarctica, but continental drift has since separated them. Fossil nothofagus wood, seeds and pollen have been found in Antarctica.  There is also a relict population of nothofagus in montane New Guinea, but it is not known when it arrived there. As Fred suggests, the southern taiga may also have included Wollemia pine, but this has yet to be proved.


What caused peak CO2 to rise, starting about 400,000 years ago? This question assumes the accuracy of this (and similar) charts.

Source of image.

From the image, CO2 peaked at about 260, perhaps 265 ppm during the interglacial periods between 800,000 years ago to the interglacial which ended about 480,000 years ago.    Beginning around 400,000 years ago, CO2 ppm reached about 280 ppm and repeated or exceeded that peak during the next 4 inter-glacial periods.

I understand that CO2 can play a feedback role, where as the oceans warm, less CO2 is absorbed and that can lead to higher CO2 ppm in the atmosphere, but whether the question is focused on the CO2 ppm or ocean temperatures, it's basically the same.   What was the cause for lower peak temperature and/or lower ocean temperature leading to lower peak CO2 in the atmosphere during that time period.

Northern Hemisphere insolation doesn't explain it.   That underwent even wilder swings during the lower peak CO2 period.

First things first: There's nothing per se wrong in science with answering "We don't know" to a vexing problem. This might well be one of those cases.

The question you are asking was asked by Imbrie and Imbrie in 1980. The problem you have noticed (a very strong interglacial despite low Milankovitch forcing) is now known as the "stage 11 problem", and this appears to be closely associated with the transition from a ~41000 year glacial cycle to the ~100000 year cycle we have seen for the last 900000 years.

Why "stage 11"? This is a reference to the concept of Marine Isotope Stages, depicted below. The Marine Isotope Stages refer to the abundance of oxygen 18 relative to oxygen 16. Water made of two protons (hydrogen) and one oxygen 16 atom evaporate more readily than does the slightly heavier water centered on an oxygen 18 atom. This makes the oxygen 18 levels in oceanic deposits a very nice proxy for climate.

Source: https://skepticalscience.com/print.php?n=1703

Three key transitions can be seen in the above graph. The glacial cycle started to change from a ~41000 year period to a ~100000 year period a bit less than one million years ago. The second transition occurred after MIS 17 when glacials shifted to being more extreme. The third transition, the one that you noticed, occurred after MIS 12 when interglacials shifted to being more extreme. This latter shift is the core of the "stage 11 problem".

The key issue with explaining the observed ~100000 year cycle is that the Milankovitch forcings for a 100000 cycle are rather low while the Milankovitch forcings for a ~41000 year cycle are very strong. The stage 11 problem gets at the very heart of the 100000 problem because stages 12 and 11, which mark an extremely large swing in climate, occurred when Milankovitch forcings were very low. One non-solution of this stage 11 problem is that the onset of stage 11 (or possibly the onset of the preceding stage 12) represents when the 100000 year cycle finally took full control. This is essentially the argument made by Berger and Wefer.

So, rhetorically, what did cause this shift from a glacial cycle of ~41000 years to ~100000 years, and why did it take half a million years for this transition to become complete? A partial explanation by Abe-Ouchi et al. is that something happened between 0.4 and 1.0 million years ago that enabled hysteresis loops. Instead of disappearing on a 41000 cycle, ice instead built up to such thick levels that all of the ice didn't melt at what would have ended a 41000 year glaciation. Once that happened, it wasn't much of a jump to survive two 41000 year cycles. But by then the ice had become so very thick that all that was needed was a mild forcing from warming to make the ice melt catastrophically.

This still falls in the "and then magic happens" category. One very plausible hypothesis that has gainied a lot of traction (e.g., Bintanja and Van de Wal) is that those massive ice sheets eventually pushed the built-up regolith from the 200+ million years since the previous ice age (the Karoo) either out to sea in the north or in huge piles of glacial drift to the south.

The initial glaciation events of the current ice age that started about 2.6 million years ago were rather weak in part because regolith makes for a rather nice ice lubricant. Those comparatively weak glaciation events continued for the next 1.6 million years, at a 41000 year interval. Much of the regolith had been pushed out of the way by a million years ago. While regolith is slippery (to ice), bare rock is anything but. This stickiness enabled ice to build up to the extent that those hysteresis loops could start to form, sporadically. It took another half a million years for the transition from a purely Milankovitch-driven 41000 year cycle to a Milankovitch+hysteresis 100000 year cycle.

References:

Imbrie, John, and John Z. Imbrie. "Modeling the climatic response to orbital variations." Science 207, no. 4434 (1980): 943-953.

Berger, W. H., and G. Wefer. "On the dynamics of the ice ages: stage-11 paradox, mid-Brunhes climate shift, and 100-ky cycle." GEOPHYSICAL MONOGRAPH-AMERICAN GEOPHYSICAL UNION 137 (2003): 41-60.

Abe-Ouchi, Ayako, Fuyuki Saito, Kenji Kawamura, Maureen E. Raymo, Jun’ichi Okuno, Kunio Takahashi, and Heinz Blatter. "Insolation-driven 100,000-year glacial cycles and hysteresis of ice-sheet volume." Nature 500, no. 7461 (2013): 190.

Bintanja, R., and R. S. W. Van de Wal. "North American ice-sheet dynamics and the onset of 100,000-year glacial cycles." Nature 454, no. 7206 (2008): 869.

Prof Malte Jansen and his team at Chicago University have found that when the sea ice surrounding Antarctica increases, it cuts off the supply of CO2 from sea to air, which would explain the lows. When the sea ice retreats, that might explain the highs.

You will immediately be thinking that the normal course of events is that CO2 moves from air to sea, so why should things be different in Antarctica? The Southern Ocean is extremely deep and cold. Deep, cold water holds more CO2 than shallow warmer waters. In the area surrounding Antarctica there are rising currents from vast depths, laden with CO2. Normally when these currents reach the surface, they deliver some of their excess CO2 to the atmosphere, then dive back down into the abyss where hydrothermal vents replace the CO2. When the surface is covered with ice, this gas delivery is halted, so atmospheric CO2 is reduced. Conversely, when the sea ice recedes the delivery of CO2 resumes, perhaps at an accelerated pace because of the build up of CO2 when deliveries were halted.

This mechanism could explain or partly explain the highs and lows on your chart, but does not exclude the possibility there may be other mechanisms at work as well. Prof Jansen is convinced that the scenario set out above explains ice ages and why they do not always fit comfortably with the Milankovitch Cycles. Obviously the increased albedo of advancing ice cover is another factor which helps to bring on an ice age.


What is the deepest we have ever gone into the Earth? I remember Journey to the Center of Earth and wonder: What is the deepest in the Earth surface or below sea level we have traveled either by foot, sub, drill or camera?

Probably a bit over 4 km, in this South African mine: https://en.wikipedia.org/wiki/Mponeng_Gold_Mine  But as the link mentions, the mine operators go to considerable lengths to reduce the mine temperature to endurable levels from the  66°C/151°F of the surrounding rock.

Note: This answer is for the original question, where the OP asked for the deepest depth below the surface.  It's since been changed to ask for depth below sea level.

http://cracked.tumblr.com/post/162183647834/the-mponeng-gold-mine-in-south-africa-is-the

The book "Blind Descent" by James M. Tabor details this answer and I found it a terrific read.
I can't recall the exact depth, but what stuck in my mind was one particular explanation where the author said that we (humans) have gone as far below sea-level as above it. That is, roughly equivalent to the height of Everest - well over 8km.


How probable is is that earth magnetic field will change 180 degrees at once? Today the Earth's magnetic field is moving a little bit. But is there going to be a point where the field suddenly radically changes direction? If so what is the cause of that? If not, then is the field changing all the time gradually?

The magnetic north pole (and presumably the south pole) currently moves around 40km/year, although within a year it loops around, may travel much further than that forwards and backwards. Here is a map of the movement from the past century and a half (source)
:

However, during a magnetic reversal, the pole may move up to 10 times faster than that, over a period of less than 100 years. Here's a map showing the relative movements (the numbers are thousands of years ago (kya)) (source)

]

The reason for reversals aren't very well understood (according to the previous link), and I'm in no way an expert in the field, but just for some fun speculation, I would wonder whether reversals might be related to this phenomenon. Obviously a liquid outer core is going to operate differently from a screwdriver, but the two systems both appear to be exhibiting a bistable rotation while floating in space.

Magnetic field exist because of the hot liquid in the external core of Earth moves, that movement of charged particles produces the magnetism.
Therefore, the magnetic field can't change at once, it only can change slowly with variations of these inner flows.

I "suppose" that earthquakes might produce small changes in the magnetic field, because seismic waves travel through the Earth core and mantle.


Is the term "fertile ash" a misnomer? I understand that volcanic ash contains minerals and can make soil more fertile.

But I've also heard the term "fertile ash" in some documentary (I have forgotten in what context). Is that a scientific term, or a  misnomer?

The Oxford online dictionary contains the following definition of "fertile":

http://www.oxforddictionaries.com/definition/english/fertile

  1 (Of soil or land) producing or capable of producing abundant
  vegetation or crops: the fertile coastal plain

  1.1 Producing many new and inventive ideas: her fertile imagination

  1.2 (Of a situation) encouraging a particular activity or feeling: conditions at the time provided fertile ground for revolutionary
  movements

  2 (Of a person, animal, or plant) able to conceive young or produce
  seed.

  2.1 (Of a seed or egg) capable of becoming a new individual.

  2.2 Physics (Of nuclear material) able to become fissile by the capture of neutrons.

By that definition, ash alone cannot be described as fertile.

Perhaps a philosophical point, but if it's not valid according to this dictionary, and it's not a scientific term either, then I suppose it's more a question of correct English, so maybe I should reword my title to ask if it's a scientific term.

'Fertile ash' is not a scientific term, but neither is it a misnomer. Unless the ash is deposited really hot - hot enough for the particles to weld together as 'ignimbrite', then the ash deposit has high porosity and permeability. As soon as water infiltrates, the anhydrous minerals start weathering to clay - generally smectite, or mixed layer clays. This released aqueous magnesium, silica, and low concentrations of other elements crucuial to plants. Thus, both the texture and chemistry of volcanic ash is conducive to plant growth.

When the volcanic island of Surtsey emerged from the Atlantic, just south of Iceland, in the 1970s, plants started to establish themselves in the volcanic ash within a matter of months.

The ash(which contains minerals), is, by virtue of its containing minerals, fertile in the sense of 1.2 from the oxford online dictionary quoted in the question, "encouraging a particular activity or feeling"  Sure that line does say  'fertile ground' as it says "encouraging a particular activity or feeling: conditions at the time provided fertile ground for revolutionary movements"     But that usage of fertile could be applied to ash that contains minerals.

Not fertile in the sense of producing, but fertile in the sense of encouraging. Which is also a sense mentioned in the OED/Oxford English Dictionary quoted by Point "causing or tending to promote fertility"


Is everything affecting everything on Earth? If a single butterfly can alter the future, then can't every single action keep the future in chaos? According to the question about butterfly effects, this must be so, is it not?  If this is an accurate description of the physical world, if so many things act continuously on other things, is there a way to predict anything or action at all?  If so, why are we worrying about it?

Do you know what the weather will be in four hours time? You can probably make a very confident guess. How about this time tomorrow? You can probably make a reasonably confident guess. How about this time, in fourteen days exactly? Now, you're much less confident.

That's because weather is a chaotic system, and it's very sensitive to boundary conditions.  In such a system, very small disturbances can make very big changes, far enough out.

Now, for Wisconsin (as that's what the OP's profile gives as their location), let's think about the external air temperature at 05.00 on 1 February 2017, and at 14.00 on 1 July 2017. Which do you think will be higher? Will it be a difference of a few Kelvin, or more than ten Kelvin (18°F) difference? How confident are you in your answer? You're probably very very confident that the July temperature will be higher, by more than ten Kelvin. The climate is still reasonably predictable months or years ahead, even though it gets very hard to predict the weather reliably more than ten days ahead. Climate is a long-term system, and is not sensitive to boundary conditions in the same way that weather is.

If you roll a fair six-sided dice once, you can't be very confident about whether a one will come up, however much you know about the air movements in the room when you throw the dice (you can be reasonably sure that the probability is 1/6, however much you know about the air). However, if you roll that dice 6000 times, you can be reasonably confident that one will come up a thousand times, give or take a hundred times, and you don't need to know anything about the air movements in the room.

That's the difference between weather and climate; even though weather is just a manifestation of climate, it's just a sample from the climate distribution.

We've built the global economy, patterns of habitation and movement, food supplies, energy systems, around the climate that we've had for the last few hundred years. And that should be ok, because climate, sea levels and sea pH levels normally take between thousands and millions of years to change radically. But our releases of greenhouse gases are now causing big changes to happen within years to decades: and it will be enormously expensive, disruptive, and cause huge suffering to billions of people, to reorient the global economy, patterns of habitation and movement, food supplies, and energy systems, to newer, unknown, unfamiliar climates, coupled with rising sea levels and ocean acidification.

From experience as a cross continent truck owner-operator, the effect of an insect's beating wings on the earth is minimized or even neutralized by the mass of the truck when it hits the radiator. Logical thinking and close observation reveals this minimizing effect.  Just like when we hauled 285,000,000 honey bees, their combined flying power was too minimal to offset the mass of 35,000 pounds accelerating down the open road at 60 mph.
By inference therefore, the added weight of one bug plastered to our radiator does not alter the weight or speed of the vehicle.  If this logic bears out, then the beating of one set of wings of a lovely butterfly, will not be a deal breaker.


How would plate tectonics differ if Earth had no water? Water plays a crucial role in plate tectonics by easing the brittle and ductile deformation of the Earth's lithosphere. Water lowers the Mohr-Coulomb for brittle fractures. During ductile deformation, it lubricates different deformational regimes. This is also important for the deformation in the asthenosphere.

In addition, water plays an important role in the formation of water-bearing minerals and the fluxing of melts, thereby substantially changing the rheology of the lithosphere and asthenosphere.

So, what would plate tectonics look like on a waterless Earth? Would it even work? Would there be different rates, or totally different processes taking over, similar to what is seen on adjacent solar system bodies?

Sources:
V.S. Solomatov. The role of liquid water in maintaining plate tectonics and the regulation of surface temperature

See also:
Plate tectonics and water

One way of looking at this question is to determine if Earth would possess an active-lid (multiple plate), stagnant-lid (single plate) or an intermediary state (e.g. episodic or sluggish) tectonic regime.  This is one of the reasons comparisons are often made with Venus, especially in regards to the main difference been that Venus has a stagnant-lid with possible episodic active tectonic regime (see question and answer to Can Venus be considered to be tectonically active?, compared to Earth's active-lid tectonic regime.

However, there are other differences between Venus and Earth that also may account for the differences in tectonic regimes, asides from the relative absence of water on Venus. Some modelling by Bouffard, (2013) indicated that different plastic yield strengths of lithospheric rheology could account for the different tectonic regimes.

How water interacts oceanic lithosphere is a vital consideration for this kind of question, considering that most spreading ridges and all subduction zones are based on the oceanic lithosphere.

This answer is based on how the absence of water may have prevented a key theorised tectonic mechanism from even starting.

A crucial role for water is modelled by Regenauer et al. (2001) for the initiation of subduction and as they assert the beginning of plate tectonics, based on the theory that long term build up of sediment at a passive continental-oceanic boundary (e.g North American east coast) may have caused the strain to build up to a point where the oceanic crust 'breaks' and starts subducting, as shown in the diagram below:

Image source

In the absence of water, this process of subduction initiation (should it be true) could not have started; as the authors believe could be the case for Venus where volcanism is evident, but the mechanism appears to be hotspot activity through the current stagnant-lid tectonic regime observed there - if this theory were true, then the absence of water would mean that Earth would potentially have had a stagnant-lid, punctured by hotspot activity.

References

Bouffard, 2013, Role of water in the tectonics of Earth and Venus, University of Lyon

Regenaeur et al. 2001, The Initiation of Subduction: Criticality by Addition of Water? Science

The short answer is that we don't really know for sure.

In the larger scheme of things, a plate is simply a thin (and cool) boundary layer at the top of a convecting cell. Plates are a result of mantle convection and their composition will have little effect on convection itself.

At the same time water tends to lower melting point of mantle rocks which can have many important consequences, e.g., back arc volcanism (as water gets transported to great depths during subduction), onset of instabilities etc.


After days of smoky air, why is it healthier to stay inside? A large wildfire has been burning for four days some distance from my town. The air is smoky, but not smokier than yesterday or the day before. General wisdom holds that we should all stay indoors.

As I enjoy my relative safety and indoor accommodations, I wonder why the indoor air is safer than the outdoor air. Even buildings that had 12-foot-wide (4-metre-wide) cargo doors open yesterday contain air less smoky than the outdoor air, or at least it smells that way.

Are still there fewer smoke particles per unit volume indoors? Do indoor environments trap the particles better? Why is the air safer indoors?

If you're in the open air you will be exposed to the full concentration of the pollutants in the air. By being inside, there's a reasonable assumption that the rate of interchange of air between inside a house and outside will be low and that inside there will be a lower concentration of pollutants.

Houses and buildings are not hermetically sealed. The gaps around windows and doors are small which results in low rate of airflow between the outside and inside of the houses and buildings. The less windy the weather the lower the flow rates.

The other way to consider it is when a room has been closed for a lengthy period while someone has been in the room, the air in the room becomes stuffy. This is because the air in the room is not being replaced by fresh air quickly enough to remove stuffy air. To remove to stuffy air the windows and doors need to be left open for a period of time for fresh air to replace the stuffy air.

The same thing happens when the air outside is heavily polluted. The air inside is cleaner and remains cleaner for a longer period if the doors and windows remain shut because the rate of transfer between air inside the building and outside is small.

Unless your house has a comprehensive HVAC system with air filtration the air inside the house will be just a polluted as the air outside of it.
Breathing rarified smoke is not dangerous. Remember that before ovens and stoves people heated their houses with fireplaces and breathed smoke all day long, every day--way more smoke than you would ever be exposed to by a distant forest fire.
The air inside your house is probably way more polluted than the air outside of it because of all the toxic shit you bring into the house and release, such as: bathroom cleaners, window cleaners, "air fresheners", toilet cleaners, waxes, polishes, nail polish, perfume, deodorants, the car, hair spray, etc. Also, there are lots of things in your house that outgas highly toxic, carcinogenic substances including: computers, phones, audio equipment, anything rubber, anything with volatile oils and lubricants like motors, anything made out of fabric treated with fire retardent (upholstery, clothing, rugs, curtains, etc). Then, of course, if you have a modern house it is made of drywall, so you are constantly breathing gypsum dust (calcium sulfate), and if the house is insulated, then you are also  breathing particles of fiberglass. Get the picture?
The government tells you to stay inside because they want to control you.


Is it physically possible to see mountains from 500 km away? Quoting from lecture notes of Andrew young at San Diego State University:

  For less extreme, but very reliable, observations, consider some listed by Commander C. L. Garner of the Coast and Geodetic Survey in 1933 [...] He also credits the 1911 sighting of the Fairweather Mountains in Alaska [highest point is Mt. Fairweather 15 325 ft or 4670 m] from the ship Explorer from the Gulf of Alaska, 330 miles [531 km] away."

Earth’s mean average radius is 3959 miles by a right angled tangent of 330 miles gives a hypotenuse extending well above the surface of the earth of sqrt(39592 + 3302) = 3973 miles. Subtracting the radius 3959 miles gives the drop in the curvature of the earth from the beginning point where the Explorer made the sighting: 13.7 miles, or 72 492 ft.

72 492 ft minus Mt. Fairweather’s height 15 325 ft gives 57 167 ft to spare for a whole mountain range to disappear beneath the curvature of the earth.

What could account for this sighting 'through' the curve of the earth?

I think what was observed is a superior mirage. A superior mirage occurs when warm air overlies a very cold layer of air, aka an inversion. You don't often see a superior mirage in lower latitudes, but they seem to be somewhat common in and near the Arctic regions.With normal atmospheric conditions and taking into consideration refraction, about the furthest one could see a 15,325 foot mountain from, say, a 100 foot high deck is roughly 177 miles, depending on the tide. The only possible explanation is a very strong superior mirage.There are a couple of good articles here and here that describe the conditions necessary:

The question I'm answering is:  Is it physically possible to see mountains from 500 km away?

It is very likely possible to see the top of Mt. Everest from the top of some mountain that is 500+ km distant. The other mountain would have to be at least 10000 feet high and be located 500 - 550 km from Mt Everest, and there has to be no other mountains blocking the view.  Much better would be a 20000 ft high mountain because then you could see over 10000 ft high mountains in between


Forest fuel biochar burial Record fires are blazing in the west coast, huge even compared to California's notorious summers.
Dead plants and debris are crucial to get a fire started. This debris could be collected, carbonized, and buried, say as terra preta.  Biochar burial has been considered as a way to mitigate climate change.
Cleaning up thousands of square miles of brush would be a massive undertaking. But we would avoid the pervasive and persistent loss of air quality on top of an already high health cost as well as tens to hundreds of billions of dollars from property damage, economic disruption i.e. evacuations, and other costs such as fighting fires. Would the combined benefit to cost ratio be competitive compared to the "typical" climate, health, or economic program?

The effects of biochar burial in California would be so minuscule they might be a net negative once you include the CO2 production of the labor involved. Biochar is a very labor intensive process. Consider carbon in fossil fuels was accumulated of millions of years of what is essentially the same process, even industrializing the process will still take comparable amounts of time to resequester that carbon using what is basically the same method. keep in mind fire is a normal part of many of these environmental cycles they are bad because humans kept preventing the normal fire cycles allowing fuels to build up for decades. Normally that fuel would be cleared by the natural fire cycles. Drought is a trigger not the cause.
Large impact estimates assume we would have to be converting land to biochar production, which has many many downsides and still would not be very effective.
It can be particularly confusing since "Bio-char" can mean two different things, the most touted use of biochar (fertilizer) will have no real carbon sequestration effect but can be a way to offset industrial fertilizers. Burial would sequester some carbon, but would also deplete soils and biodiversity. You have to check and see which use of biochar a source is referring to.
A better idea would be to burn the material as fuel, instead of fossil fuels, which would at least be carbon neutral.
source

There's No real evidence Biochar helps to sequester co2. Turning bioenergy crops into buried charcoal to sequester carbon does not work.
The biofuels ‘scam’ has already proven to be a dud. From corn to ethanol, algae experiments, etc and tropical crop related fuels. All they do is speed up deforestation and peatland destruction, deplete water and soil for agricultural sustained fuel production, and increased the use of farm-chemicals to meet quotas. Above all, it has generated  land grab, land conflicts, human rights abuses, labour abuses, starvation and food insecurity.
Worse Biochar according to research is a notorious oxygen sink.
https://www.permaculturenews.org/2010/11/18/beware-the-biochar-initiative/