Is it possible to create an enclosed manmade weather system? There are plenty of experiments, usually geared toward kids, that involve "making a cloud in a bottle" or something similar.  These exercises are neat for what they are, but pale in comparison to the beauty of real clouds.  Really you're just making fog in a bottle.

Using currently available (preferably consumer grade) technology, is it possible to create real clouds?  Or even better, a real weather system?  Imagine you have an enclosed 10 ft wide cube.  If you build a landscape inside, complete with mountains and bodies of water, and you have complete control over the boundary conditions of the cube (temperature, airflow in/out, etc.), can you reproduce the beauty of a towering cumulus cloud inside the cube? One step further... can you create thunderstorms?

I have a very rudimentary understanding of how weather works, but the engineer in me says in theory this should be possible.  But in reality a lot of small details glare out at me as possible show stoppers.  Aerodynamics does not scale, because of the constant size of air molecules at all scales.  I suspect this limitation may affect my weather system puzzle as well.  Also with respect to thunderstorms, I suspect the 10 ft wide cube may not be able to mimic the role of planetary grounding, atmosphere, etc., in the creation of electric discharges.

Real clouds are beautiful because they are huge and you observe them from far away, thereby gaining the ability to see a distinct "boundary" and, therefore, shape. But if you ever travel through a cloud in a plane, thereby seeing one close up, you'll find that they really are "just fog". You'd struggle to recreate a scale cloud in a tiny environment; water molecules have a reasonably consistent size and you can't just downscale the entire system.

Similarly, you could probably create a thunderstorm but at that scale it would be over so fast you'd barely see it. An obvious example is the movement of water droplets as steam leaves your kettle and condenses. You just see a quick whoosh of vapour particles spiralling about and, well, that's about as close to a rainstorm as you'll get.

Some phenomena, such as air vortices, can manifest at smaller scales — I've seen more than a few mini-tornados forming in my garden dragging leaves around in a funnel fashion — but I'm not sure you'd ever be able to contain enough energy to see that happen for more than a fraction of a second in a small tube.

You just need a big enough space,. and you need freezing cold air at the top of it, then warmer air at the bottom, and water vapour, that condenses. Then you might get rain, even snow forming depending on the temperatures. Is the conditions right you even get clouds. Now If you want to create a thunderstorm, you need air movement as well, upward ,downward, sideways and so on. And you defnitely need to produce hail and strong rain. In theory its probably possible, but its very very costly (you need a large scale building/hangar or dome, Nasa has one ;)) and very very expensive equipment to make it work, on the other hand once you have it, you have created something no one else has ever built) and you can control the weather in your closed environment.


Why rely on climate models as opposed to paleoclimate data? Something I hear often from climate scientists, and indeed even politicians, is that we "don't understand climate change very well". And, I'm sure this is true since the climate is a complex adaptive system with thousands of dependent variables, one that we don't yet have the computational sophistication to accurately model. But that doesn't mean we don't know, to a high degree of accuracy, what is going to happen if we make certain changes to the atmospheric composition or take certain actions. We have paleoclimate data ranging extensively far back many hundreds of thousands of years, encompassing global temperature, climate cycling, atmospheric composition, and more.

Sure, the global temperature 100,000 years ago wasn't measured using a thermometer, but we've used various independent proxy methods that all agree with each other to a reasonable degree, right? And so do we not then have a reasonably accurate idea of Earth's climate sensitivity by simply looking at precedent? And paleoclimate will be close to exactly right since it takes all the variables into account exactly in the amount they're needed to be accounted for. Why are we still "uncertain" about the realities of climate change? Why are we not moving on and taking decisive action based on this--what seems to me--reliable, accurate data?

We need both paleodata and models, in fact the relationship between paleodata and the climate at a certain time is typically evaluated through models. Paleodata does not actually measure climate observables directly (tempreture/pressure/salinity/other) but instead is (e.g.) a geochemical quantity related to one of those.

For example, the two most frequently used records are the Antarctica EPICA ice core record and the Lisiecki Raymo benthic stack. The isotopes in these records are affected by temperature at a point on the planet and global ice volume, but how that relates to global temperature and the size of individual ice sheets requires inference from climate models.

Further, climate (or earth systems) models can allow us to probe what could happen in addition to what did happen. Current CO2 levels are reaching a point not seen in the ice core record (our most direct records) and so we need increasingly complex models to get a handle on the range of possibilities.

It is true that we don't understand climate change very well for the reasons you give in your question, namely that there are so many variables involved and some of them are unknowns. Indirect methods of assessing climate composition and temperature are reasonably accurate for the last few tens of thousands of years, but the further you go back, the more scope there is for error to creep in.

Computers are helpful, but not the be-all and end-all. Garbage in, garbage out, as the old saying goes. There comes a point in the prehistorical climate record where palaeontology is the best guide to what ancient climates were like. Paleoclimatic data can't be exactly right when you get to this point because it is too far back, and although palaeontology can tell you what sort of climate we had millions of years ago, it can't explain what part CO2 abundance played.

Changing the composition of the atmosphere is more difficult than some people imagine. Oxygen and nitrogen are present in countless trillions of tons, and the oxygen is constantly being replenished by photosynthesis. Most photosynthesis takes place in the oceans. This same photosynthesis is also removing CO2 from the atmosphere. Because CO2 is only present in trace amounts, it is the only atmospheric constituent we can do anything about, with the possible exception of methane.

The fact that plants grow more vigorously in an atmosphere where CO2 content is enhanced adds another complication. There is no serious doubt that atmospheric CO2 has increased since the industrial revolution got well underway, that climate change is real, and that we are currently in a warming phase, but whether CO2 is the sole cause of it is another thing. Action is being taken to reduce CO2 in the atmosphere, but not enough to make a measurable difference. The reason much sterner measures will not be taken is that the major industrial countries which are the main emitters are worried about the damage to their industries and economies if they do everything that environmentalists want.


Does depletion of Planck radiation intensity in the upper atmosphere mean that "CO2 has no impact on climate change"? In his recent book, Rex J. Fleming asserts that "CO2 has no impact on climate change", or, as he summarizes on his website:

  There are now over a dozen books available on Amazon.com that point out the various fallacies of the CO2 climate theory – but none of these have zeroed in on the heart of the issue – the failure of the Schwarzschild radiation integrations to maintain the CO2 longwave radiation intensity achieved in the surface warming by H2O and CO2. The resultant Planck radiation intensity is severely depleted in the upper atmosphere. The result is the CO2 molecules merely pass their remaining small residual heat to space un-impeded. CO2 has no impact on climate change.

This claim seems to contradict some basic physics.

Is Fleming correct that the "failure of the Schwarzschild radiation integrations to maintain the CO2 longwave radiation intensity" means that "CO2 has no impact on climate change"?

Talk of Schwarzschild radiation integrations negating the effect of CO2 in atmospheric warming is just mumbo jumbo on a par with creationism, but there is a danger of going too far in the other direction. Carbon dioxide forms 0.0325 percent of the atmosphere, and although a slight increase has been recorded in the past 100 years and attributed to human activity, this increase is infinitesimally small. Whenever I say that climate warming began 12,000 years ago it is always very unpopular, but it nevertheless happens to be a fact. There is unanimous agreement among scientists that the small amount of CO2 in the atmosphere helps to warm the Earth, but where there is less agreement is on the question of whether the minute increase since the industrial revolution has measurably accelerated the climate warming which had already been underway for 12,000 years. Another unpopular idea which also happens to be a fact is that increased atmospheric CO2 causes plants to grow more vigorously, so to some extent increased CO2 content is self-correcting, but only up to a point. It could easily be overwhelmed if the CO2 increase is too rapid.


How is Doppler radar used in rain prediction? How is Doppler radar used in rain prediction?

The easiest answer is that Safe Haven is a movie, and the writer made a factual error (which is not uncommon). I have not watched that movie, so I am unsure what type of situation they were dealing with. Doppler radars do not predict, but they observe.

What is possible, however, is extrapolation and the creation of inferences. For example, tornadoes are not directly predicted by Doppler Radar, but by making inferences from the data, a meteorologist may detect a tornado. In a similar sense, if the radar-derived 'storm total precipitation' has estimated an average 0.25 inches of rain from a squall line for the past 200 miles, one may extrapolate, or estimate, that the squall line will produce ~0.25 inches of rain. Could the squall line alter its path or intensity and drastically change the amount? Sure, but without additional information, including information not derived from a radar, that would be a difficult task.

Edit: Ok, I think I have a better idea of what the question was and how it can be answered.
Doppler radar can measure wind speed relative to the radar site. So if can sense how fast a storm is approaching. Assuming the storm does not change it's speed, and given it's history, you can infer when it will arrive at the radar site. For example, if a storm is 50 miles away, and it moves at 25 miles per hour it will arrive in $50\text{ mi}\div 25\frac{\text{mi}}{\text{hr}}=2\text{ hr}$, provided the storm does not change.

Doppler radar is not used any differently to predict weather than older forms of radar were, satellite imagery is, or how physical observations that were then called or telegraphed ahead of an advancing system.  The radar detects the presence of clouds with a water load that are likely to produce precipitation, or may already be doing so.  That is compared to the direction the potential precipitation is moving and historical records of when similar conditions have occurred in the past, how likely is it to be repeated for a given location.

An observation is made, hey there is a cloud back forming there that seems to hold a lot of water.  It is moving in this direction at this speed and the barometric pressure is doing this with a temperature like that.  The last 10 times we had conditions that matched this, it rained 7 times, so, let's say there is a 70% chance it is going to rain.

Doppler radar is, in general terms, a more sensitive form of making these observations than older radar was, which was more sensitive and actuate than having physical observers a few hundred miles away calling and saying, hey, it's raining here.  You will probably get rain in a few hours.


Zeolites, odor control, and the witchcraft of sunlight Various companies offer "volcanic crystals" or "volcanic rock" available in small mesh bags for odor control.  The best description I have found is that these are made up largely of Zeolites.  All of these manufacturers suggest that the rocks will trap odors and to just recharge the rocks every 6 months by putting it out in direct sunlight.

This sounds like witchcraft!  Can someone explain why putting the rocks in sunlight (versus other light) recharges them and makes them effective at trapping odors again?  How does the light "release" the odor?  Is it the heat of the sunlight, or could this be used in the winter as well?

Zeolites are very similar to clays, with one key difference. The molecular structure of clays is rather compact. In contrast, the molecular structure of zeolites has tiny molecular-sized holes, and these holes are wont to connect. The result is a porous, tunnel-filled structure at the molecular level.

The resulting tunnels make zeolites very good at absorbing substances that fit very nicely in those tunnels. What those substances are depends on the zeolite. There are a large number of naturally occurring zeolites, and even larger number of manufactured zeolites. Which zeolite absorbs what substance depends very much on the nature of the holes in the zeolite. As an example, the International Space Station uses a particular kind of zeolites ("zeolite 5A") to selectively absorb carbon dioxide from the breathing atmosphere.

Zeolites would need to be discarded after becoming saturated if all they did was absorb stuff. That's not the case. It's rather easy to make zeolites relinquish the stuff they have absorbed because the absorption mechanism is rather weak. All it takes is a smallish amount of energy. Zeolites used in industrial settings are subjected to heat, noxious chemicals,or both to make them relinquish the stuff they have absorbed.

In addition to having a large number of industrial uses, zeolites have apparently become attractive to the "all natural" crowd. (I suspect the larger number of "non-natural" zeolites are verboten amongst this crowd.) Exposing zeolites to sunlight means they absorb heat and ultraviolet light. This is indeed one way to make zeolites reject whatever has been absorbed. That's not very efficient; it would be much more efficient to bake those zeolites and/or expose them to a series of caustic chemical baths. However, that wouldn't play well with the "all natural" crowd.

The way to go is bung them in the microwave or oven. But then your oven will smell like cigarette smoke etc. Best in the sunligh/ patio where the odours can dissipate in open air. Nothing to do with witchcraft. It is simply an absorbent volcanic rock, much like a dense pumice.


Is it feasible to 'harvest' the clathrates from the permafrost before they evaporate? We can see that there are large buildups of methane clathrates in permafrost regions.

Climate scientist James Hansen has predicted that the release of the permafrost methane clathrates could cause runaway climate change.

We know that some have related the Triassic Extinction event to the release of Permafrost Clathrates.

I know that there are various techniques to extract natural gas from shale and rock.

My question is: Is it feasible to 'harvest' the Clathrates from the permafrost before they evaporate?

No, it's not feasible. They are too dispersed, and any operation to harvest them would be too costly and inefficient, and would amount to vandalism on a gigantic scale. We just have to hope that the vast majority of tundra clathrates will remain un-melted, as will probably be the case. The last time they were melted on a massive scale may well have been the Permo-Triassic extinction event of 250 million years ago.The Arctic tundra is a vast natural wilderness full of valuable wildlife. Any ill-judged operation to remove clathrates would not only be grossly expensive and inefficient, but would have both taxpayers and environmentalists up in arms!

Assuming theories of the Permo-Triassic event are correct, it took the long term eruptions of the Siberian Traps super-volcano to release almost unimaginable quantities of CO2 into the air to trigger the melting of clathrates. Eruptions of super-volcanoes like the Siberian Traps 250 million years ago and the Deccan Traps 66 million years ago make modern volcanic eruptions, even Krakatoa (1883) or Tambora (1815), pale into insignificance.


Would the climate still rise when we reduce our carbon footprint down to zero? Every electrical device consumes electric energy and almost every one of them I can think of produces heat as a byproduct. This also applies on every kind of machine powered vehicle. Even our bodies produce a small amount of heat. Almost everything produces a small or high amount of heat. This only gets more and more with more people on this planet and continuing industrialization. Just think of all the giant production around the world and all the means of transportation - they all produce a massive amount of heat.
If you put hundred cups of hot tea into one room the room temperature rises as the tea cools, right? This is heat transfer.
I asked myself wether we would still have a negative effect on the climate even when we (could) reduce our carbon footprint down to zero today or not. We would still produce a lot of heat with almost everything we do.
To what extent has heat production a negative effect on the climate compared to co2 emission?
And why is heat production never payed attention to?

While I can't comment on whether the global temperature would still rise if humanity's carbon footprint were reduced to zero, I do know that the heat our machines produce would not contribute any net warming effect. The issue is not the amount of heat which is entering the atmosphere -- it's where and when that heat came from.
Assuming that we are successful in reaching 100% wind, water, and solar energy, the energy consumed at the end use would be from only seconds to at most a year ago:

Seconds: Solar power from photovoltaic panels is collected, converted to electricity, transmitted to the grid, and used almost instantaneously
Hours to days: Wind is primarily generated by daily fluctuations in surface temperature caused by the sun
Months: The water in rivers which power hydroelectric dams is generated by seasonal patterns in precipitation, which is a function of changes in solar intensity over the course of the year

In contrast, the energy we're using today from fossil fuels is tens to hundreds of millions of years old, containing energy harvested from the sun over a period of over a hundred million years (source).
The energy from wind, water, and solar sources is being added to our atmosphere anyway -- we just convert it into different forms to use it for other purposes in between its transit from the sun to the planet.
By contrast, the energy from fossil fuels had been locked away, safely stored for 100 million years or more. Until we started drilling and mining, it was no longer having any significant impact on the planet.
This also applies to the food we consume -- the energy that fruits and vegetables store is at most a year old -- for animal products, it's at most two to three years old.

Uh yeah, slightly because a cessation of co2 emissions isn't removing the centuries worth of prior emissions, however that's a while from now. The temps been rising since 1750's before the industrial revolution. But CO2 on Earth has been steadily declining, we're in the midst of a coldhouse period and a carbon drought which is perpetual. When humanity unleashed fossil fuels they put Co2 back in the atmosphere, we've been regenerating the biosphere with carbon, the building block for life. More co2 means more bioproductivity. Greenhouse growers understood this decades ago

Even ocean life, contrary to popular claim the oceans get more acidic, in co2 enrichment, more carbon means more building blocks for shelled creatures. Experiments show bubbling more co2 means they creatures get Bigger.


Why do clouds have areas of darkness instead of scattering light to produce a rainbow? I suspect it has to do with the difference in size of a rain drop and that of the water particles in the cloud.

It really depends on the cloud. Actually, it depends on its density and thickness which is related to concentrations and type of hydro-meteors in it, the size distribution of water droplets and ice crystals, and shape of ice crystals.

Rainbows are formed by the refraction and internal reflection of light in water drops (usually rain).

But cirrostratus clouds can form a halo by refraction on ice crystals in shape of hexagonal prisms. These halos have angular radius of about 22 degrees.

Another optical phenomena that you might find interesting is a corona around the Sun or the Moon which is caused by diffraction of light on water droplets and tiny ice crystals. Angular size of a corona depends on the size of water droplets.

'Areas of darkness' are due to the density and optical thickness of a cloud. More ice crystals and water droplets cause more scattering which results in less light reaching your eyes making a cloud appear darker.

Not an expert but I believe it has something to do with water vapor vs water droplets.

When you were in elementary school and used a prism to produce a color spectrum the prism was a clear solid, somewhat like a water drop is a clear liquid. Reflectivity occurred with that mass and produced a color spectrum. When this occurs within rain it is called a RAINBOW!

Next question?


When was it ever considered that the desert might be "man-made", or otherwise anthropocenically-induced? This answer pointed me to the Wikipedia page for Farouk El-Baz in which the desert research and theories subsection says:

During the past 20 years in his research at Boston University, El-Baz has utilized satellite images to better understand the origin and evolution of desert landforms. He is credited with providing evidence that the desert is not man-made, but the result of major climatic variations. His research uncovered numerous sand-buried rivers and streams in the Sahara based on the interpretation of radar images.
These former water courses lead into depressions in the terrain, which he theorized must contain groundwater. His analysis of these data resulted in the location of groundwater in the arid terrains of Egypt, Oman, and the United Arab Emirates (U.A.E.), and perhaps Darfur in Sudan (unless it dried up).

I was surprised to read that the "origin and evolution of desert landforms" was ever considered to have an anthropocenic component.
Question: When was it ever considered that the desert might be "man-made", or otherwise anthropocenically-induced? Is it possible to know which desert was thought to be man-made that El-Baz proved wasn't? Or does the passage refer to all deserts?

El-Baz has utilized satellite images to better understand the origin
  and evolution of desert landforms. He is credited with providing
  evidence that the desert is not man-made, but the result of major
  climatic variations.

  Does the passage refer to all deserts?

Geolmorphologists classify deserts as zones that take place in climatic arid regions where rainfall is relatively low, there are extreme daily temperature variations and the vegetable cover is reduced or non-existent. The climatic conditions result in desert typical forms as hamadas, caliches, or dunes. (Gutiérrez Elorza, M., 2008).

It is important to note not every arid region is a desert, but every desert, with particular forms, is an arid (or hyperarid) zone.

Source: research.net

The question is: can Climate Change and deforestation create deserts?

Answer is Climate Change and deforestation can create new arid zones. It can create the conditions to expand existant deserts, but the typical desert forms take some time to form, so deserts as El-Baz have not (yet) grow because of our actions on the planet.

However, other deserts as Sahara have expanded his area in the last century (Thomas, N. et al., 2017). The article of this asseveration quotes (anthropological) Climate Change as the main factor of this expansion.

So answering your question the passage you quote does not refer to all deserts if you consider man-made something that result from our emissions of greenhouse gases to the atmosphere.

Gutiérrez Elorza, Mateo (2008): "Geomorfología", Ed. Prentice Hall.

Thomas, Natalie and Nigam, Sumant (2017): "Twentieth-Century Climate Change over Africa: Seasonal Hydroclimate Trends and Sahara Desert Expansion". Journal of Climate, vol 31.

All the major deserts are naturally formed by climate change in ancient times. Much of the Sahara, as recently as six or seven thousand years ago, was savannah of a sort now found in East Africa, and with a similar flora and fauna (acacia, crocodiles, giraffes, gazelle, lions, ostriches etc). However, deserts can be man made, and a good example of that is the dust bowl of mid-west USA in the 1930s. The dust bowl was caused by bad farming methods which made the land unable to withstand a few years of drought. Wind created enormous dust storms of a kind which sometimes occur in the Sahara or Australia, and this blew the topsoil away, so farmers had to leaved their land and find work in the cities.

Special farming techniques managed to restore most of this man made desert in the forties and fifties, so I think I'm right in saying that most of it is now productive farmland again, but not so productive as it would have been if the dust bowl had never happened. Another example can be found in the Sahel, where overgrazing by livestock has transformed some areas into desert over the last 50 years.


Colder winters along the North American Atlantic northeast Why are winters along the North American Atlantic northeast coast colder than winters along the North American Pacific Northwest coast?

As air moves over the surface of the earth, the properties of the surface (such as temperature) can alter the air. Since at those particular latitudes, the predominant wind direction is from the west and partially the north, it is important to note what is north and west of both locations.

West of the northeast Atlantic is land, and northwest is Canada. This means that the air is drier, and prone to have characteristics of mimicking continental- polar (cP) air. Continental polar air tends to be dry (since it is over land) and cold (since it is coming from an area that receives less sunlight).

West of the northwest pacific is the Pacific Ocean, and northwest is still the Pacific Ocean. This means that the air is more moist and prone to have characteristics mimicking the air over the ocean, called Maritime polar (mP). Since the water tends to warm slower than the land and also slower than the land, the air over the water is usually warmer during the winter and cooler over the summer than the air over the land.

To summarize:

At those latitudes, the wind usually blows from the north and west.
During the winter, air over the ocean is warmer than air over land.
North and West of the Northwest coast is the Pacific ocean, while land is west of the Atlantic coast.
Therefore, the winter in the northwest coast is usually warmer than the winter along the northeast coast.

Winters are colder on the Atlantic northeast coast partly due to a slight difference in longitude/latitude of Newfoundland is 53.1355’N - 57.6604’W as opposed to say Vancouver British Columbia on The Pacific NorthWest. 49.2827’N - 123.1207’W. the distance from the equator is greater.

The second and more profound part of this answer; has to do with weather patterns, Wind directions, high/low pressure systems, warm/cold fronts. Jet streams.
Prevailing winds produced by ocean temps and currents.

To be more specific the North East coast of Canada expirences low pressure systems barring down from the Canadian north as you can see in the “wind speed model I have provided. Commonly reffered to as an “ nor-easter” fisher men slang for trouble.

The west coast experiences a tropical jet stream called the Pineapple Express. This bring with it warm moist air and lots of precipitation
Please find attached a currents wind direction graph.

Kind Reguards
Jeff B.

Pacific NorthWest

Atlantic northeast coast

enter link description here


Trees: What does "highly tapering stem" mean? Trees: What does "highly tapering stem" mean?

Taper is a function measuring steepness of change in crown diameter when height increases upwards.

But "highly tapering" (sometimes also "high-degree of taper")? Is it "a large change in taper" (large steepness) or a "fine change in taper over a long height" (low steepness, but high fineness of change)?

A "highly tapering stem" is simply that the trunk of the tree is less cylindrical and more conical in profile. It's a problem because while you may have a lot of timber volume you don't have as much timber that is usable because you'll end up with a higher proportion of sawmill waste.

I'm English and have a degree in forestry. Regardless of comments elsewhere, a "highly tapering stem" is perfectly good terminology, although I agree that it could be clearer. I would tend to say "a high degree of tapering" or a "more tapered stem" for clarity's sake.

A full description of this can be found in Forest Mensuration: a handbook for practitioners by Matthews and Mackie on page 114. (They refer to a tapering log, because they are discussing felled timber).

It means that the tree is thick at the base, but rapidly becomes thinner as it ascends. The use of "stem" is anomalous. An Englishman would speak of 'a highly tapering trunk'. Stem is used when referring to much smaller plants.


Southern Hemisphere climate Does oceanic and land mass positioning affect tropical storm evolution in the southern hemisphere? And, do cold fronts migrate latitudinally " upwards " the way they drift "downwards" in the northern?

The fact that there is much less land mass in the southern hemisphere affects the climate and sea currents, but the situation is otherwise much the same as the northern hemisphere. Cold fronts tend to move north, whereas in the northern hemisphere they tend to move south. Hurricanes and typhoons are less common in the southern hemisphere, especially in the south Atlantic, and drift south, where there is less land to get in their way.

Cyclonic tropical storms form where ocean waters are heated by tropical or subtropical sun, and this heat is the source of their power. In the north, the Caribbean and Gulf of Mexico are a prime source of hurricanes because the ocean is hemmed in by land and heats up more easily than the south Atlantic. Hurricanes here do more damage and attract more attention than they would in the less populated vastness of southern hemisphere oceans. Just as hurricanes from the Caribbean tend to move north, those forming below the equator in the Indian ocean, where they are called typhoons, tend to drift south toward the vast emptiness of the Southern Ocean.


Recreating the rock cycle I want to recreate the rock cycle using some item that can behave as a rock. The purpose of this is to get a point across to my students about how really there is a reason why the rock cycle is called rock cycle.

Most of them find rocks dull and uninteresting, so I was thinking about proving the rock cycle some other way. In a couple of hours researching I came across some surprising ideas, such as crayons, chocolates, wax, etc.

I wanted some feedback on how well you think I can get the point across of the rock cycle being a cycle. To them, thinking that something liquid, turn into solid, then gets destroyed, and mixed into something else, then melted again, is really hard to understand. Using something that does not take millions of years to form might be a better strategy I think.

Here's an idea:

You can use dark chocolate and white chocolate. Use a grater to create "sediments": layers of alternating grated dark and white chocolate.

Now heat them up just before melting so you can stick them together with pressure, preserving the layered structure. Now fold them. There's your "metamorphic" rock.

Then, just melt the entire thing to create some chocolate-lava flows. Grate them again and eat!

If you want to stick to actual geological products rather that kitchen substitutes, you could demonstrate the properties of an extraordinary natural evaporite mineral, Mirabilite, Na2.SO4.10H2O. This is found in some of the East African salt lakes, amongst other places. Under dry conditions it dehydrates to a white powdery mineral, Thenardite. Under warm conditions it dissolves in its own water of crystallization.  In some East African lakes, Mirabilite saturated water splashes on the beach by wave action, where it dries out as crystals. Then when it warms in the sun, it turns back to a liquid and drains back into the Lake. It's a phase change rather than a chemical change, but it gets across the message of cyclicity.


Climate change research and policy How impactful is climate change scientific research on climate change policy?
Are there any statistics which help to visualise the effectiveness of new scientific findings or new technology innovation inducing a change in government policy to help kerb climate change?
Even any papers regarding this will be appreciated.

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

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

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

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

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

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

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

Climate change research has a big impact on government policy with some governments, but not all. Governments are in a tricky position, on the one hand they would like to appease climate change hysteria and play it safe, on the other hand they don't want to handicap their industries, lower national prosperity and raise unemployment by fulfilling the demands of the greens and taking drastic steps to reduce CO2 emissions. There is no doubt at all that climate change is happening, because it has always been happening. At present we are on a warming trend which began about 12,000 years ago. At present, atmospheric CO2 levels are about 400 parts per million and rising, but they have been a lot higher within historical times, and far higher within the last half-a- billion years. An added complication is that it is impossible to distinguish between anthropogenic CO2 and CO2 from natural sources, and there are many other factors which complicate the issue.

Take glacial retreat for example. There is scientific consensus that most glaciers are melting and on the retreat, but a surprising number, hundreds rather than dozens, are advancing. This is not to say there is no global warming, scientific opinion is that global warming is a reality and that rising CO2 levels will exacerbate it, but by how much is uncertain. A further complication is that increased CO2 levels promote increased plant growth (by plant growth I mean everything from rainforest, peat bogs and agricultural crops to marine cyanobacteria, algae and phytoplankton),so to some extent rising CO2 levels are self-correcting. There is a danger, however, that this self-correction mechanism could be swamped if CO2 levels rise too quickly.

One thing you can be sure of is that the reductions in CO2 emissions which environmentalists tell us are necessary will not be met or even almost met by the major emitters. Regardless of whether countries like UK meet their targets or not, major industrial countries like USA, China, Russia and India won't. That is a fact that people will just have to get used to, and if the consequences are catastrophic (lets hope they won't be) we will just have to live with them. Perhaps the start of the next ice age will rescue us; despite Milankovitch cycles they are not entirely predictable. There was a 450-year Little Ice Age, beginning about AD 1350 and ending about AD 1800, which no one can explain. Scientific advances like electric vehicles will help, but it will take a major breakthrough like the perfection of fusion reactor power stations to make a really important difference.


What is the fastest ocean deep current? The Gulf Stream is the fastest ocean current in the world with peak
velocities near 2m/s.
Source: marine.coastal.edu

What about deep currents, North Atlantic Deep Water, Antarctic Bottom Water, etc?
What is the fastest ocean deep current?
My guess is Antarctic Bottom Water must be the fastest because Antarctic Circumpolar Current receives not salty water from ice melt, and salinity gradient moves deep currents.
Is Antarctica Bottom Water the fastest?

This article in Fox News points to this paper and asserts that the fastest deep current measured is the Antarctic.

Rintoul, of the Antarctic Climate and Ecosystems Cooperative Research
Center in Hobart, said it proved to be the fastest deep ocean current
yet found, with an average speed of 7.9 inches a second (0.20 m/s).

I have no access to the paper, I can only read the abstract. I guess Fox News didn't lie this time as they are sourcing a scientifical paper of Nature Geoscience.
Fukamachi, Y., Rintoul, S., Church, J. et al. Strong export of Antarctic Bottom Water east of the Kerguelen plateau. Nature Geosci 3, 327–331 (2010). https://doi.org/10.1038/ngeo842

The gulf stream is the fastest under water ocean current inthe world ,with peak velocities 2 meters per second ,the gulf stream, at the straits of Florida and cape hatteras.enter image description here


Gases that are nearly transparent to solar AND thermal radiation? I've been curious about if there are any gases in the atmosphere that are nearly transparent to both solar and thermal radiation. $CO_2$ for instance is nearly transparent to solar radiation but is partially opaque to thermal.

I've tried to find information on internet, but the large amount of information about global warming is effectively hijacking my google searches.

Edit: When I say solar radiation, I am not just referring to that which is visible. Please consider at least infrared, visible, and UV in your answer.

Any help or insight will be greatly appreciated.

Google Radiative (or radiation) absorbtion coefficients for gases (or enter specific gas of interest). Most of this data relates to applications in combustion and refrigeration so that is the area to look at. To avoid "contamination" from all the global warming stuff try looking at older things like papers from the 1950's. I have some detailed refrigeration books from the 50's which I think had this data but not to hand right now. Or see if you can get hold of some books like that from your library or a bookstore.

Many gases were studied in great detail with proper experimental measurements to verify well before global warming was a thing. You can find graphs of lots of useful things which can help you with an understanding of how the various gases might work in the atmosphere. For example using the emissivity of CO2 to calculate radiative heat transfer in the atmosphere with the standard Stefan-Boltzmann equation when you know the concentration of CO2 is, say, 400ppmV. Emissivity of CO2 can be surprisingly low at atmospheric concentrations, temperatures and pressures, less than 0.002 typically.

All radiation is thermal. I really can´t understand why anyone makes a difference between different parts of the spectrum. The "visual" part of radiation is entirely relative to human eye-sight. The definition of visual is exactly that, the radiation which the receptors in our eyes respond to. The concept "albedo" is also something entirely relative to human eye-sight, and it should be questioned if it is correct to use it for a planet in regards to temperature at all. For example, snow is like a perfect blackbody absorber outside the visual spectrum, but in the visual it is reflective. And solar radiation is 51% IR(thermal), so what use do we have of "albedo" when we calculate temperature?
 "Thermal" radiation is entirely based on the fact that human eyes doesn´t respond to those wavelengths, and the rest of the longwave radiation parts of the spectrum is called non-thermal mostly because humans can´t sense it at all.

"Solar radiation" cover the spectral parts where we say that the gases in question is opaque, although wavelengths are mostly in the higher frequency part. So the "transparent" parts apply to both solar and thermal, with your definitions.

The fact is, all radiation is thermal, intensity and wavelengths depends on the temperature of the emitter, only. Any part of the spectrum has an intensity according to the temperature of the emitter, spectral resolution and peak intensity of emission is also caused by the temperature of the emitter. The entire concept of radiation in the universe is an exclusive relationship where emission depends on temperature alone. If we know this, which we do, then all radiation is thermal. And nothing on earth, no matter what gases are involved, should interfere with that relationship, because it would be a violation of 100% consensus physics. Emission is dependent on temperature alone, absorption is due to temperature only. Spectral resolution is quantum physics, and we don´t use that for temperature. Now, if you want to discuss spectral character of something, that is fine. But if we are talking about temperature, of the atmosphere or earth surface, transparency should not be involved.


Does clearing snow contribute to climate change? I've been reflecting on climate change and pondering how much of it is truly man-made. Anyone who's shoveled a walkway know that the snow melts faster beside the walkway than it does in the middle of your yard. This is because you've exposed the ground which can absorb the sun's heat. Whereas the snow in the yard reflects it.

The same is true of glaciers: They melt away from rock faces (ie, terminal morrains, bergschrunds, etc.), and as more of the Earth's surface is exposed, the more heat the surface of the Earth can absorb, and the faster the rest of the Earth's ice can melt.

Consider the combined surface area of all the roads and parking lots that are cleared of snow each winter (as well as the increased number of roads and parking lots which capture a lot of heat each year). Snow clearing to the scale as is seen in recent decades far exceeds what has been accomplished in the past. Even as recently as the early 20th century people still made their way around on top of the snow in sleighs.

How much of a contributor to climate change can be attributed simply to roads and the relatively modern practice of snow removal?

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

Although snow clearance makes a theoretical difference to climate change by reducing the amount of solar radiation reflected, the difference to average temperatures is negligible, so small as to be unmeasurable. In most cases the snow would melt within a few weeks anyway, so clearance makes no practical difference to global warming.


Why does Earth have abundant oxygen in the atmosphere? Because of photosynthesis, obviously.  But then it's not actually that obvious after all, because photosynthesis is mostly balanced by respiration.

We can summarise the processes of photosynthesis and respiration like this:
$$\begin{align}
\ce{CO2 + H2O + h\nu} & \rightarrow \ce{O2 + CH2O(biomass)} \\
\ce{O2 + CH2O(biomass)} & \rightarrow \ce{CO2 + H2O}
\end{align}
$$
If these two reactions were always balanced then the concentration of $\ce{O2}$ would never have changed. If I understand correctly, there are abiotic processes that deplete $\ce{O2}$ to form iron oxides, and so in order for there to be persistent $\ce{O2}$ in the Earth's atmosphere, the biosphere as a whole must continually produce an excess of it. In order for this to happen, there must be some processes that consume biomass at a non-neglible rate without removing a corresponding amount of $\ce{O2}$ from the atmosphere.

My question is, what are the processes primarily responsible for this? Is it just due to the burial of unoxidised organic matter (to form coal, oil, etc.), or is there more to it than that?

If they are different processes, I'm interested both in what caused the excess of oxygen during the "great oxidation" event, and what maintains the excess of oxygen on the modern Earth.

This is only a partial answer as it doesn't explain why the excess of O2 stayed but one thing you have to appreciate is the fact that aerobic respiration appeared almost half a billion years after photosynthesis, so we can't really say that photosynthesis and respiration have always balanced each other.

Cyanobacteria (and with them photosynthesis) are believed to have appeared somewhen between 3 and 2.5Ga (e. g. Altermann & Kazmierczak 2003, Brocks et al. 2003) while Mitochondria (and with them aerobic respiration) are thought to have evolved somewhen between 2 and 1.5Ga (see e. g. Hedges et al. 2004).

There was therefore at least half a billion year during which cyanobacteria were producing O2 with no one able to breathe it.

I will explore the answer admitting that the Earth's temperature in the ancient past was much higher than we now assume as possible. The current standard model is the 'Snowball Earth' which leaves many unsolved problems - see 'Faint Young Sun Paradox'.

I will assume that the total amount of $\ce{H_2O}$, $\ce{CO_2}$, $\ce{O_2}$ is substantially constant throughout the entire history of the earth.

All the water of the oceans would stay in the atmosphere layer   provided the temperature was high enough. The percentage of oxygen would be $\approx 0$ because it would be masked by the massive presence of $\ce{H_2O}$.

Later, when the temperature dropped, the water has migrated to the ocean floor and the percentage of $\ce{O}$ exploded to current levels. This fact is called the 'Great Oxygenation Event' and it is not very well understood under the standard model.

About the free Oxygen origin: (Copy / Paste)

  "There are two known natural ways of producing oxygen: by UV
  dissociation of H2O and by photosynthesis. In the ECM, the former
  process was initially much more efficient than at present because of
  the huge amount of water vapour and of the greater intensity of UV
  radiation occurring then. The biological production of oxygen would
  have been important during the Archean, which ended at
  2.5 Ga, therefore earlier than the GOE. The usual approach is to consider that the biologically produced oxygen was first combined with
  dissolved iron in oceans and only significantly released to the
  atmosphere later – a way to explain the delay between the presumed
  time of the biological production of oxygen and the rise of its
  atmospheric level. Here, there is no need to consider a delay – the
  biologically produced oxygen was dissolved in water and absorbed by
  the huge atmosphere without significantly changing its composition;
  the oxygen level increased only when the atmosphere significantly
  decreased due to the condensation of water vapour. One can now
  consider that oxygen was produced in large amounts since the
  beginning, first from UV dissociation, at a rate that decreased over
  time, and very soon followed by biological production. In this case,
  there was an important amount of free oxygen in the atmosphere long
  before its atmospheric level started to increase significantly; and
  some potential evidences of it can be identified (for a review see
  Yamaguchi, 2005)."

ECM stands for Evolving Climate Model where this new concept was brought to life in a formal document (if you wish to explore further you can follow the 2nd link in my profile, not peer-reviewed)

EDIT add:
Although no one wants to peer review the document of ECM,(*) its graph on fig.9 provides modeled data that is aligned with the most recent measurement of Oxigen.
Measures goes against all of the accepted models ( 5 times more Oxigen at 815Ma), as seen on fig 4 on this news
http://motherboard.vice.com/en_uk/read/scientists-release-air-that-has-been-trapped-for-800-million-years

On the contrary the Fig. 9 of ECM
Fig. 9. The variation of Oxygen volumetric ratio in the ECM1 due
to the variation of the size of the atmosphere, holding the
amount of Oxygen constant (thick blue line). The grey lines
represent the limits for the oxygen volumetric ratio (partial
pressure in the atmosphere) estimated in Holland (2006)

ECM is not peer-reviewed but it predicted the data to be seen (it is Data-reviewed) !

(*) ECM is a creation of an engineer, and scientists assume that science is not for engineers.

note: This new measurement enable to say: Oxygen first, Life second, rendering erroneous most of the answers one can find around.

Why so many down votes (5) if it is notorious that none could find an error in the document?


Does the long-term ice-core temperature record provide reasonable evidence that the current temperature trend is not anthropogenic? When looking at the long term ice-core temperature record, it very clearly shows a ~100,000 year cyclical trend with warming spikes and gradual cooling. To the untrained eye, it seems that such a trend has not been significantly deviated from so far (in the present day). This would indicate to me that the current upward temperature trend is not human-caused. What refutes that idea?

Also a relevant question: what is the confidence of this temperature record and what are the probable deviations from the temperatures indicated in that graph?

No, ice cores do not refute human-caused warming.  In fact, they support it.  Your logic really doesn't follow because the rate of warming now compared to some arbitrary previous date is not  related to whether the warming is driven by humans.  Instead, it is important to consider the natural variation of physical factors that affect climate (collectively known as Malenkovitch cycles; http://en.wikipedia.org/wiki/Milankovitch_cycles ), and then recognize any large deviations from those cycles.

An image of the EPICA and Vostok ice cores versus age obtained from http://en.wikipedia.org/wiki/Ice_age , clearly shows influence of the Malenkovitch cycles.  The most notable of which is the strong cycle that is approximately 70,000 years and is associated with geologic ice ages. In fact, the Earth is historically on average much cooler than it is now, and the retreat of glaciers has been periodic but not sustained.  We were supposed to have cooled off some time ago, but clearly we are not in a global cooling period. Many would even argue that humans started affecting the climate over 7,000 years ago when land management and fire was wielded prevalently.

In order to attribute climate change to humans, climate models are run with and without anthropogenic climate forcing.  When they do so, climate models run without anthropogenic forcing are unable to duplicate the current warming trend.  I've attached an image of this from the IPCC AR5 Technical Summary draft which shows a full climate simulation, one without anthropogenic climate forcers, and one with no aerosol forcing for comparison.

Finally, I thought someone might value this link that discusses climate change atrribution:
http://www.realclimate.org/index.php/archives/2014/08/ipcc-attribution-statements-redux-a-response-to-judith-curry/comment-page-4/

My current understanding is that, while the trend over hundreds of thousands of years has not (yet?) been significantly deviated from, the rate at which the temperature has been rising over the last 100 years has been unprecedented* (I concluded its not in fact unprecedented, see below).

I'm not entirely sure that the rate is in fact unprecedented, but I could certainly see it being that way. Look at the graphs at https://en.wikipedia.org/wiki/Temperature_record , it looks like:

Between about 14 thousand years ago and 7 thousand years ago, the temperature rose by 8 degrees, which is 1.15 degrees per 1000 years on average.
Between 132 thousand years ago and 124 thousand years ago, the temperature rose by about 14 degrees, which is a  1.75 degree per 1000 years on average.
In the last 100 years, the temperature has increased on average about 1.1 degrees. So that's a good 11 degrees per thousand years, which is about 6 times what looks like one of the highest rates on the long term ice core record.

So because of the different lengths of times, and different scales, its a certainty that there was variance in the rate of temperature change between 132 thousand years ago and 124 thousand years ago. This means that there were definitely spans of 100 years in the those few thousand years in which the rate of increase was greater than the average.

So this lead me to looking at the actual data the graph on wikipedia was derived from. Here's the source: ftp://ftp.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/epica_domec/ . Looking specifically at the spreadsheet called edc3deuttemp2007.xls , I see that indeed between between 132 thousand years ago and 124 thousand years ago, there are about 12 approximately hundred-year periods with greater than a 1.1 degree increase per hundred years. I took periods of three data points, which means they're not all the same exact length of time. In any case, this was from 76 3-data-point periods, so a full 15% of the time periods in that section of the data had greater temperature growth than we've seen in the last 100 years.

In fact, since 133 thousand years ago, there have been over 150 non-overlapping 100-year periods where the temperature has been rising faster than it has in the last 100 years. This is about 11% of the 100-year periods in the last 133 thousand years.

So in conclusion, based on this data, I have to conclude that the rate of temperature rise in the last 100 years is certainly not unprecedented, and thus my question still stands: why is this not compelling evidence that the temperature rise is largely not anthropogenic?

Here are the calculations I added to the spreadsheet to come to my conclusions: http://www.btetrud.com/files/edc3deuttemp2007%20-%20annotated%20with%20~100%20year%20temp%20diffs.xls . Note that the data is all in the second spreadsheet tab (the 'data' tab).


How do we know the asteroids formed at the same time as earth? In continuation of the question Why is Earth's age given by dating meteorites rather than its own rocks?, what evidence do we have that the asteroids indeed formed at the same time as earth? Is there any physical evidence, or is it a conclusion reached mostly through simulation?

what evidence do we have that the asteroids indeed formed at the same time as earth?

It depends on what is your definition as "the same time". The formation of the solar system and Earth did not happen at a particular second in time but was rather a continuous process. It also depends on what you define as "asteroids".

I'll try to put some things in order.

The oldest known material from Earth is a zircon from the Jack Hills in Australia. Its age has been recently refined to be 4382 million years. We know that because we measured it.(1)
The moon forming event occurred sometime between 4348 and 4413 million years ago.(2) Now, that zircon should be younger than the moon (because the moon forming event would destroy any already-existing minerals on Earth). Yet, there is a slight overlap between the ages. This is due to the fact that analytical capabilities have their uncertainties and error.

This means that the Earth has been here at least ~4.4 billion years ago, because you need the Earth to have a moon. The Earth didn't just pop into existence, but it formed over a period of time, in which small planetesimals collided with each other and accreted to form a larger body.

The question now is, what is the age of the planetesimals? We can't know for sure because they are all integrated into Earth, but we can look at asteroids and see their age. We do that by dating the meteorites that fall on the Earth, which in some cases are blasted off asteroids by (even more) collisions and impacts.

When you look inside a specific type of meteorites called chondrites, you can see objects that are called CAIs (calcium-aluminum inclusions). These things are solids condensed from vapourised gas that existed in the solar nebula before any planets and planetesimals formed. These are basically the first solid to form in the solar system, and they define the birth of the solar system. We know that they formed 4568(3,4) or 4569.5(5) million years ago.

Planetary bodies (which for this discussion will be considered as km-sized chucks or rock with the ability to melt and differentiate to mantle and crust, and accrete to form proper planets) began forming around 4566.2 to 4567 million years ago(5,6,7). We know that because we can date meteorites that we know originated in asteroids. This is just 2 million years after the formation of the first solid droplets in the solar system. Now, while 2 million may seem like a long time for your daily commute, it is not too long for planetary processes (considering Earth is 4.5-4.4 billion years old).

Now there is a time gap - what happened between 4566 (formation of planetesimals and asteroids) and 4413 (formation of the moon)? There are about 150 million years that I haven't talked about yet. Was the Earth gradually growing in a linear fashion during that time or did it form rather quickly? Luckily, there are answers to that as well. Based on some measured geochemical data it was shown that most of Earth's mass actually accreted ~10 million years after the formation of the solar system(8). That's rather quick! So the Earth has been sitting there, all by itself, around 100 million years until the moon formed. As to how the Earth itself formed, it could be just amalgamation of small planetisimals, collision of larger bodies, or something completely else. Chemical evidence and physical models do not always agree, and it's all highly debated.

This is a field which is rapidly evolving and discoveries are made all the time due to better analytical capabilities and better models. Just look at the years of the papers below. This is all cutting edge and a highly exciting field of study. Everything that I wrote here can be inaccurate or even plain wrong, but that's the fun in science.

  Is there any physical evidence, or is it a conclusion reached mostly through simulation?

So it is a combination of both. You find physical evidence: rocks from Earth and parts of meteorites and their minerals. You measure their isotopic composition to find their age and other characteristics. Then you make a model (or a simulation) that tries to see what has to happen in order for the physical properties to agree.

Further reading:

An introduction to Meteorites and the origin of the Solar System - a very accessible and interesting read.

Chronometry of Meteorites and the Formation of the Earth and Moon - a more technical review, may be paywalled.

Refs:

1 Valley, J. W., Cavosie, A. J., Ushikubo, T., Reinhard, D. A., Lawrence, D. F., Larson, D. J., … Spicuzza, M. J. (2014). Hadean age for a post-magma-ocean zircon confirmed by atom-probe tomography. Nature Geoscience, 7(3), 219–223. doi:10.1038/ngeo2075

2 Carlson, R. W., Borg, L. E., Gaffney, A. M., & Boyet, M. (2014). Rb-Sr, Sm-Nd and Lu-Hf isotope systematics of the lunar Mg-suite: the age of the lunar crust and its relation to the time of Moon formation. Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences, 372(2024), 20130246. doi:10.1098/rsta.2013.0246

3 Bouvier, A., & Wadhwa, M. (2010). The age of the Solar System redefined by the oldest Pb–Pb age of a meteoritic inclusion. Nature Geoscience, 3(9), 637–641. doi:10.1038/ngeo941

4 Burkhardt, C., Kleine, T., Bourdon, B., Palme, H., Zipfel, J., Friedrich, J. M., & Ebel, D. S. (2008). Hf–W mineral isochron for Ca,Al-rich inclusions: Age of the solar system and the timing of core formation in planetesimals. Geochimica et Cosmochimica Acta, 72(24), 6177–6197. doi:10.1016/j.gca.2008.10.023

5 Baker, J., Bizzarro, M., Wittig, N., Connelly, J., & Haack, H. (2005). Early planetesimal melting from an age of 4.5662 Gyr for differentiated meteorites. Nature, 436(7054), 1127–31. doi:10.1038/nature038825

6 Greenwood, R. C., Franchi, I. A., Jambon, A., & Buchanan, P. C. (2005). Widespread magma oceans on asteroidal bodies in the early Solar System. Nature, 435(7044), 916–8. doi:10.1038/nature03612

7 Amelin, Y., Kaltenbach, A., Iizuka, T., Stirling, C. H., Ireland, T. R., Petaev, M., & Jacobsen, S. B. (2010). U–Pb chronology of the Solar System’s oldest solids with variable 238U/235U. Earth and Planetary Science Letters, 300(3-4), 343–350. doi:10.1016/j.epsl.2010.10.015

8 Rudge, J. F., Kleine, T., & Bourdon, B. (2010). Broad bounds on Earth’s accretion and core formation constrained by geochemical models. Nature Geoscience, 3(6), 439–443. doi:10.1038/ngeo872

Perhaps a little step back to get a bigger point of view is required.
Take note of this line in the answer provided by Michael - "it might be plain wrong".

The question uncovers some very glaring assumptions:
1. We know how the earth was formed.
2. We know when the earth was formed.

The current theory of accretion doesn't hold much water - both metaphorically and literally speaking.
There just is no way that dust or rocks in space can accrete all by itself to form a body such as the earth. Even basic physics disagrees with this. The simulations have to ignore this basic fact and instead introduce fudge factors to make rocks and dust "stick" together when the collide.
You just go out and try making rocks stick together when they smash into each other - confirm for yourself whether it will work in space where there's even less resistance to flying apart.
Furthermore, even if one allows for some miraculous hot sludge of radioactive material to stick together, one immediately creates another problem: the exclusion of water because of heat.
There is no acceptable way for all the water on earth to arrive here from outer space. Why would the water only strike earth [ and where would it come from in the first place ] in such a way that Mars, Venus and the moon do not have any evidence of a watery bombardment?

Then there's the question of how does one measure the age of anything?

Age is unfortunately not a physical property that we can measure directly like length, volume, density, etc.

In order to know the age of anything one needs to have been present when it came into existence and then to have some way by which to assign some kind of measure of passage of time to it.
In short - age is an abstract construct that cannot be measured physically.

What can be measured is the proportions of the number of atoms of mother and daughter products of radioactive material. But having established that proportion and applying a rate of decay to determine age doesn't give a true age.
Have you ever found a record of calibration that confirms that the radioactive methodology does indeed deliver the correct age? Did someone witness and record the creation of basic radioactive rock and then track it's age using the radioactive decay method? To my mind, it hasn't been done and in fact where some measurements have been made of newly created basalt in St Helen's eruption, the ages produced are plain incorrect.
The best that it can produce is an "age" based on some very questionable assumptions.

Since we do not know the history of the earth we need to make some assumptions regarding its creation. We need some form of "clock" by which we can measure how old the earth is. That clock has to be independent of the earth itself, hence why people use meteoroids, under the assumption that it must be at least as old as if not older than the earth itself.

The main problem is that we need to know when that clock started ticking and we just don't have any means to establish an objective way to determine that.
No one was there to witness and record that event. There-in lies the problem.

Even if you assume that the radio-active decay happened at a constant rate[ which we have seen is now no longer true ], you still have to make assumptions about the quantities involved. But therein lies another problem - you don't know the origin and history of the original material - how long did IT exist before it started its radioactivity?
One can go on ad-infinitum.

So in spite of the highly "scientific" answer provided by Michael, the fact is that one cannot determine the age of the earth without making some highly metaphysical assumptions about the origin of the universe. You have to make some questionable unsubstantiated assumptions as to how the whole universe came into being.
It cannot be determined scientifically, in spite of using the latest and greatest technology in cosmology today.
We simply weren't there. We have no eye-witness account. We have no record.
The best we can do is make assumptions of the starting point.

You may not like this answer. You may even get angry at seeing it but unfortunately for you, you cannot push it's validity out of the way.


(Why) Is there more landmass on Earth's Northern hemisphere than the Southern Hemisphere? This Question on Worldbuilding is based on the presumption that there is a greater amount of landmass on the Earth's Northern Hemisphere than there is on the Southern Hemisphere.

While researching to form an answer to this question, I found it difficult to find a map that accurately portrays which hemisphere actually has a greater landmass, and started thinking about the actual nature of the question - assuming there is a greater concentration of landmass in the Northern Hemisphere than the South, why is that?

Does it have anything to do with the rotational procession of the Earth? Is it more related to the Earth's natural fault lines?  Or is there something else that influences a greater accumulation of land mass on our Northern Hemisphere (if that is, in fact, an accurate assumption)?

It would be a strange coincidence (but of course possible) if the landmass would be exactly evenly divided between the northern and southern hemispheres, as defined by the equator. However, you can cut the globe with another plane and form two hemispheres that have the same landmass, eg. any vertical plane that goes through the Geographical centre of Earth.

Calculation of Geographical centre of Earth by whuber at GIS stackexchange

The landmass distribution is largely depending of the location of the continental plates, but Global Paleogeography maps also suggest that the breakup of Pangaea follows other laws than an even distribution between north and south hemisphere.

The problems to find a map that accurately portrays which hemisphere actually has a greater landmass, is probably related to the fact that many popular (and in many ways useful!) map projections are not made to show area relations. Use a globe or equal area projection to compare the size of landmasses.

This might also be an interesting article for you and a starting point for further research: Riguzzi et al. (2009) Can Earth's rotation and tidal despinning drive plate tectonics?. The authors argue that there is a correlation between tectonic movements and rotation of the Earth and the Moon's revolution plane. Tomographic data of slab dip angles support the point and this might also be part of an explanation why earthquakes and volcanism varies along the latitudes and might be rare in the polar regions.

Floating continents on a rotating sphere follow the "right-hand rule". A dynamic force vector acts toward the north on a globe spinning counter clockwise, when looking down upon the north pole. I surmise that over eons, land masses have been relentlessly forced northward with a measurable angular momentum.

A casual glance at the tapered appearance of South America, Africa, Greenland and the Indian subcontinent add anecdotal evidence to the theory. South America looks like a bubble moving northward with greatest mass at the north and a thinning tail on the south end. India, again with a tapered southern edge, has been moving north so dramatically that the Himalaya mountains were shoved skyward.

I've never heard this theory advanced by anyone, but it seems plausible to me. Alfred Wegener offered his tectonic plate theory in 1912. This would be a corollary to that.


Methane leaks from biogas Lately, I have been thinking about biogas and the impact leaks might have on climate. Biogas is mostly methane, and we know that methane has a much higher global warming potential than $\sf{CO_2}$. There will inevitably be leaks from biogas production plants, vehicles running on biogas, and other infrastructure.

In Norway, sorting of food waste has been introduced in many areas. This food waste is taken to a treatment facility where biogas is produced, and the leftovers from the biogas production are used as bio-fertiliser. The biogas is used to power buses and dustcarts in and around Oslo. The climate effect is then positive, since you are using a resource that would otherwise be wasted, potentially turning into methane at a landfill.

My question is: how large would the leaks have to be to counteract the positive effects?

how large would the leaks have to be to counteract the positive effects?

Trying a ballpark estimate ... biogas replaces natural gas. For simplicity let's assume the replacement is 1:1, one mole of methane from biogas* replaces one mole of natural gas. This also means that one mole of biomethane "saves" one mole of CO2.

Methane is about 25 times more intensive in terms of cliamte change than CO2. So if 100/25 = 4% leaks, the positive effect would be offset.

The factors influencing gas leakage, from biggest to smallest influence (this is mostly from memory):

Retention time of substrate in gas tight system - depending on retention time in the digesters, the digestate could still have 10% or so of it's total biogas potential, when the digestate storage is open and the HRT is short. One of the later iterations of the German rennewable energy laws specifies 150 days retention time in the gas tight system for this reason & I think this is reasonable for many substrates.
Leaking foil roofs - foil roofs are common on large tanks, especially the connection foil roof/digester is a common point for leakage. This study found leakage rates from plants between 0 and 20 Nm³/h (median 5-10 Nm³/h), size of plants was not given but probably around 500 Nm³/h biogas production.
Methane slip - I don't have numbers to go by, but I think 0.5-1% of gas slip (unburnt gas in the exhaust) in IC motors is common. This regardless of wether you burn natural gas or biogas, AFAIK.
Manure storage - some wastes will ferment on their own, esp. manure.
Everything else - IMO the art of building gas pipes etc. is pretty well developed, if proper procedures are followed and proper materials used leakages from pipes should be neglible.

In summary, the methane loss of biogas plants may well be above the 4% cutoff point I mentioned above, or well below, depending on plant design and quality of building.

However, as you pointed out in comments to your question, you need to also look at what would happen to the feedstock without biogasification. Manure would ferment (but not as completely) in an open pit and emit gasses. Municipal wastes would be either incinerated (likely with additional fuel because of the high moisture content), composted or landfilled (landfilled wastes also ferment and produce biogas, if this goes to the atmosphere, is flared or used productivly depends on the site). I have worked in landfill supervision and design of biogas plants.

At this point, I lack good numbers to really compare biogasification to other disposal paths. Having worked in landfill supervision and design of biogas plants, I have more trust in a properly designed biogas plant to keep methane out of the atmosphere than in a typically, well maintained landfill. But I'm sure you can find shoddy biogas plants that leak, for the same amount of input, worse than some landfills!

Likewise, I'm still looking for hard numbers of fuel usage for incineration of biowastes, so I can't offer a good comparison here.

So IMO, while biogas from energy crops is highly questionable, biogasification of wastes is a net benefit if done properly.

*biogas is anything between 50 and 70% methane, the rest CO2 and traces.

This cannot reliably be answered.

To work out whether something is better, worse or the same scientifically you need first the theory of what thing changes what other thing and secondly the formulae to calculate it.

With regard to the CO2 in the atmosphere we have a theory that more CO2 will make the Earth hotter. We do not, as yet, have an accurate formula.

Answering the question for CO2 is tricky. We think we know what is happening but it's not yet at the stage we can calculate it accurately. This is why IPCC reports on predicted global warming have ranges with degrees of certainty. Maybe doubling CO2 in the atmosphere will increase average global temperature by 0.7 degrees in 100 years, maybe it will be 7 degrees. Not really sure yet, still working on it.

So if it has taken this long, with this much money, to get as far as this fuzzyness with CO2 I doubt we can answer your question in your lifetime for methane.


Is it possible to get trapped in a circle of water in a rip current? According to the YouTube video Rip Currents: How to Survive the Deadliest Ocean's Trick, a rip current occurs when there are two circles of water spinning close to shore in opposite directions such that the water between them is flowing away from shore. My question is

  Is it possible to put yourself in a position where you're inside a spinning circle of water associated with a rip current and there's no way to escape from it without swimming underwater until you're rescued?

I don't know if that's possible or not. Maybe the water on the surface in a spinning circle is flowing around the circle and towards its centre and the water below the surface is flowing away from the centre. I won't get into the question about whether it's possible to escape the circle by swimming underwater. I think in that situation, the best thing is to swim directly away from the centre and not to swim against the current and let yourself keep being dragged around in circles. Even if you do that, the rate that water is flowing towards the centre might still be too fast. This is pretty much a yes no question so I think it should be easy to provide an answer that actually answers my question. Researchers might then be able to use the answer to invest in research on the best strategy to escape from a rip current.

Ok, i try an answer based on your clarification.

Diving in a straight line in such a regime is near impossible, because sight is obstructed. A specially trained free diver may have more of a chance but will have to go to the surface several times.

Now let's assume that an unlucky swimmer finds him-/herself in exactly the depicted situation and quickly analyzes and realizes what's going on (unlikely). If they are cold blooded enbough they can try and swim to one side, then with the stream either once around or back again towards the beach. But ... things aren't usually like in a picture book. There are coast parallel streams, waves and rocks can make it difficult to get out of the water unhurt, and maybe the stream turns too far outside or not at all. There may be undertow or a breaking wave throws the swimmer on the rocks. And when outside, even in 20° warm water the survival chances are low, until a helicopter or the rescue boat arrive. And even then, finding a head of a swimmer between the waves is pure luck for the rescue forces. People have actually drowned in the middle of regattas and dense trafic searching for them. That is why it is strictly forbidden to go overboard ;-)

There is a reason why people do die in such or similar situations. In any case, the answer to your question is "Yes", a swimmer can easily find himself in a situation where reaching the land is impossible. A snorkler with fins may have better chances.

Edit: just so that you know what i am talking about, 3 random videos. Medium conditions, waves 1-2m. Dynamic conditions, waves 6-8m. Calm conditions, .5m waves.

Yes, it is possible to get trapped in a rip current, particularly if you are a weak swimmer. There are so many variables, e.g. speed of current, ability of the swimmer, his position in the current when he realises he is caught, and so on. It is impossible to recommend one escape technique which fits all situations. Don't try swimming underwater, that would be very dangerous. You will need all your breath and reserves of strength to keep you moving on the surface. Try to keep a cool head and not to panic.

If you are a strong swimmer and the rip current is only one or two knots, then a sprint for the shore against the current will very likely succeed, but if you find you are making no headway and becoming tired, better to go with the flow. There is no way of judging the speed of the current until you pit yourself against it. For a weak swimmer, this will be very alarming, so he should concentrate on keeping afloat and let the current carry him in a circle. With luck, the people on the shore will organise a rescue.

If the current has carried you right around and you find yourself approaching the shore, it would probably be worth making an attempt, this time with the current instead of against it, to sprint for the shore. There are sometimes notices on the shore warning against dangerous currents. Read these notices before going into the water.


Shouldn't we encourage consumption of single-use plastics? Plastic is a good way to sequester carbon I've heard a bunch of impractical proposals for ways to sequester carbon:  pump CO2 gas into the ground, grow trees for the sole purpose of burying them underground where they won't decompose...   and these proposals all seem impractical to me.

By contrast, it seems quite doable to allow people to consume single-use plastics, and dispose of them in well managed landfills.  (I wouldn't exactly say we should encourage the practice, not until we have bioplastics in widespread use and green energy powering plastic production).  Stringent efforts should be made to ensure the plastic is not burnt and is kept out of the marine environment.

Plastic is very chemically stable, it won't decompose and form methane or anything else, it won't bubble up to the surface, and mixed in with garbage it becomes unattractive for future generations to dig it up.

I'm also making the assumption that any oil not used for plastic production would be used instead in the transport industry or at least somewhere where it'll be put straight into the atmosphere. I think it's naive to think that if I forgo my plastic drinking straw, there'll be one more drop of oil remaining forever in the ground - it won't be left in the ground, instead it'll be made available to the transport industry.

I've tried to get an answer to this question from New Scientist, Australia's Dr Karl and basically every chemist or physicist I encounter and no-one can explain why I'm wrong.  So it seems to me governments everywhere who are banning single-use plastics are doing the opposite of what they should be doing.

Plastic isn't a good way to sequester carbon the sense that this term is usually meant.

Carbon sequestration is normally assumed to mean

  [...] the long-term removal, capture or sequestration of carbon dioxide from the atmosphere to slow or reverse atmospheric CO2 pollution and to mitigate or reverse global warming.

(From Wikipedia, my emphasis.)

This is not how plastic production works: the great majority of plastic is made from petrochemicals.  So almost all plastic is made from fossil carbon, not from carbon extracted from the atmosphere recently.

With plausible assumptions about the energy used in making plastic and its source, then turning fossil carbon into plastic which is then not burnt is probably better in terms of carbon emissions than just putting the fossil carbon straight into the atmosphere.  But it's worse (again in terms of carbon emissions) than just not making the plastic at all.

Note that there have been plastics made from plant materials, and many early plastics were made like that: Celluloid is a good example.  I thought Bakelite was as well, but it turns out it's the first one that wasn't.

tib is absolutely right in what he says, but damage to the environment and more specifically to wildlife is another reason for greatly reducing our use of plastics made from fossil hydrocarbons. Those made from biological sources are better, but have their disadvantages too. Some biodegradable plastic bags, for instance, biodegrade while the contents are still in them if you don't use them straight away.

The worst damage is done when the plastic gets into the ocean. Turtles and other marine creatures mistake plastic bags for jellyfish and swallow them. Seabirds occasionally feed them to their young or incorporate plastic items in their nests which entangle their young. Other creatures such as dolphins,sharks and turtles become entangled in plastic rope or fishing nets, and die of suffocation.

Plastic bottles are among the worst forms of plastic pollution. The sheer number of them is staggering. Tap water is quite healthy; we don't need to go around all day sipping water from plastic bottles as though we were afraid of drying out like a slug on a hot pavement. Then there is the problem of plastic micro-particles produced by the breakdown of larger items. It has yet to be established exactly how harmful these micro-particles are, but they enter the human food chain when we eat sea food.

The best biodegradable bags are made of paper, so we should return to much greater use of paper bags. I know trees have to be cut down to make paper, but done properly the forest or plantation will eventually regenerate. Packaging of all sorts is usually too lavish, and needs to be reduced.


Is a glacier advancing or retreating? How to tell? What are the most common ways you would use to tell whether a given mountain glacier is advancing or retreating, judging only by its present state by looking at it? Please list anything you can think of.
Could a stream of water flowing out from under the glacier be a sign of it retreating?

The easiest way is to look a the glacier margins. If the ice is in contact with vegetation or rock covered in lichens or moss, it means it is most likely advancing. If you see a band of life-less rock in between the ice and the first plants/lichens/moss, it means it is retreating.

Some examples I've seen myself:

This glacier in Geenland is advancing, you can see the ice and vegetation in contact

Same glacier, you can see how it is even pushing vegetation, proving it is advancing

However, advancing glaciers are the exception. In most cases they are reatreating and what you see is a band of life-less rock surrounding the ice like this:

Retreating Amalia glacier in Patagonia

The advancing or retreating state of a glacier can have different time-scales. For example a glacier can be retreating on a decade scale, but it might advance every winter, but the recession on summer is large enough to produce a net retreat every year. Small glaciers can also react very quick to weather variations, therefore even if one is receding at a century scale, it can advance one year due to exceptional snow accumulation over few years. So you have to interpret this observations with care, and consider what's the timescale at which the plants/moss/lichens can colonize the rock in the area, which in temperate and low elevations will be between a few years and a decade.
Moraines, trim lines and other features can tell you about the advancing/receding history of a glacier at longer timescales.

Just my thought.  If the glacier is at least a few degrees below 32 °F (0 °C) steady state it's probably advancing.  If at 32 °F it probably melting.


How long to melt all the polar ice? The answers to this question say that the sea level will rise 66m if all the polar ice, etc, melts.

How long will this take?

Transporting incredible amounts of heat energy to the poles and injecting it into the ice, a good insulator, so that it melts must be very, very slow. The Netherlands, London, and all the rest will be long gone for other reasons, I imagine, long before it could be completed.

I am looking for an order of magnitude minimum under which it is provably impossible for the ice to all melt any faster.  Wild and crazy assumptions are welcome, so long as they err on the side of making the ice melt faster than it would in reality - that way the estimate will always be a minimum.

The question is requesting an answer that has no practical application. So rather than improving on some hypothetical calculation, I will describe the problem and hopefully make the difficulty providing a real answer to a time frame clear.

First: "polar ice" Antarctica is located in a polar position and consists of a multi-km thick ice sheet. The Arctic is covered by sea ice except for smaller glaciers and Greenland, which is not located in a polar position equal to Antarctica. One has to remember that Antarctica is circulation-wise isolated from the rest of the planet by circumpolar circulation, both in th esea and atmosphere, a situation not met in the Arctic. Hence the term polar ice is very fuzzy and should be avoided. It is better to speak about the objects directly.

Second: an ice sheet such as Greenland and Antarctica is not a stagnant sheet of ice, it has its own dynamics and which can change over time depending on forcing and change in forcing.. Greenland is largely land based but with outlet glaciers that terminate in the sea. Although mass loss through these have seen an increase in loss, much of the Greenland mass gain and loss is through surface mass balance (snow accumulation minus ablation, melt). Antarctica is a different beast since East Antarctica is largely land based while West Antarctica is to a large extent sitting on ground below (in places several km) below sea level. Te latter situation is more unstable since the ice could disintegrate by calving (loss through ice berg formation), a process which is potentially much quicker than surface melt (of which there is currently very little in Antarctica). So one part of Antarctica is much more unstable than the other.

Now, several other processes are at play. Ocean currents are sen to produce massive amounts of submarine melt on both Greenland outlet glaciers as well as on the sea-terminating edges of Antarctica. In places, circulation models estimate up to equal loses by calving an submarine melt. This occurs at the same time as there is hardly any surface melt to speak of. So calculating mass loss by surface melt is clearly a lost cause when calving and submarine melt dominate.

Finally, in this still simplified picture, the dynamic response of the ice sheets to changes in forcing is not well understood. This means we do not know how unstable East Antarctica really is. That Antarctica will totally disappear seems very unlikely any time soon and time frames of 10^3-10^4 years is a minimum. Greenland, not being a polar ice sheet is more sensitive in that as it loses mass it is also on average lower in altitude, experiencing more melt. There appears to be a point of no return for Greenland, under which elevation the ice sheet would not be able to recuperate unless the climate cooled significantly. Again the time to melt off the ice is long.

despite the seemingly slow increase in sea level, much infra structure  in the coastal environments is threatened by only dm to m changes in ea level so the 66.1 m quoted from IPCC is not something that will happen in a life time but that does not mean the rates are not already problematic.

As a PS, I will add some relevant references once I am back home in case someone misses them at the moment.

We need some numbers.

How much ice is there?  Let's look at the Antartic ice sheet, which will be the last to go, no matter what happens.

Antarctica contains  26.5 million cubic km of ice ( reference )

1cc = 1g

1 km3 = 10 ** 15 cc

So: $2 \times 10 ^{19}\,\mathrm{kg}$ )
How much heat energy is needed to melt a unit of ice?

$333\, \mathrm{kJ/kg}$. (http://www.ask.com/question/how-many-joules-of-heat-are-required-to-melt-40-kg-of-ice-at-0-degress-c )

So we need $6 \times 10^{24}\,\mathrm{J}$

I reckon that this is the amount of energy striking the entire Earth from the sun every two minutes.  However, getting this energy from the top of the atmosphere into the ice sheet will take a little longer.
How good an insulator is ice?

$2\,\mathrm{W/mK}$ (http://en.wikipedia.org/wiki/List_of_thermal_conductivities)

Antarctic ice is about $2\,\mathrm{km}$ thick.

Let's replace this with a $1\,\mathrm{km}$ blanket of ice equivalent insulator.  In this case, if the mean air temperature ( currently -57C ) rises to $10\,^{\circ}\mathrm{C}$, then energy arrives at the bottom of the blanket ( where I assume the temperature has risen to 0 celsius and the pressure has fallen to 1 atmosphere ) at the rate of ... $0.02\,\mathrm{W/m^2}$.

Antarctica is  $14 \times 10 ^{6} \,\mathrm{km}^2$ so we are able to deliver energy at $3\times 10 ^7\,\mathrm{W}$

$$\frac{6 \times 10 ^ {24}}{3 \times 10 ^ 7} = 2 \times 10^{17}\,\mathrm{s} \approx 7 \times 10^{9} \mathrm{years}$$

I think we can all relax!


Source of Dresser Formation 3.5 Ga dating I've seen many papers and sites that give the dating of Australia's Dresser Formation as 3.5 Ga (variously 3.48 or 3.49 Ga), but I can't seem to find the source of this.

Where does the dating come from, and what is it based on?

From Australian Government- Geoscience AustraliaAustralian Stratigraphic Units Database:

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

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

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


Hypothetically, what would happen to the earth if a large hole was drilled through the center? This may be a slightly unusual question. I know it wouldn't be possible, but what would the short and long term effects be, if a large (say, 1 mile diameter) round hole appeared, and went straight through the center of the earth, through the crusts on both sides. Would it be different if they opened on land, rather than ocean?

The best place to ask this question is going to be at xkcd: http://what-if.xkcd.com/ but I will give it a shot.

I'm not a geophysicist, but I'll try to give you a reasonable enough answer.
As you said, making such a hole is not possible.

However, let's try to think what if some magical force made a hole 1 km wide and then suddenly released it. This is what the Earth is made of:

(taken from here: http://www.nature.com/nature/journal/v479/n7374/fig_tab/479480a_F1.html)

The easiest part to explain will be to see what happens in the core. Both the inner and outer core are basically made out of impure iron. The liquid iron will just flow into itself and close the hole rather quickly (think about a similar hole in water). The solid iron is also ductile as there high pressures and temperatures, so it will also flow and close the hole. Think chocolate close to the melting temperature. It's still solid, but it moves. Probably some of the liquid iron will manage to flow into the hole of the solid iron, but it will then solidify because it will have to endure higher pressures.

Now, what happens at the mantle? The lower mantle is also ductile and it will also flow under the pressure. You have to remember the the walls of the hole are under huge pressures - 24 to 136 GPa according to the figure. Some things may "fall inside", but remember that it has to fall over hundreds of kilometers while the hole is only 1 km wide.

The upper mantle is where it becomes interesting. This is just thinking out loud though. The upper mantle is where magmas are being formed, and one of the reasons magma is formed is decompression. Usually this happens because of mid ocean spreading or mantle plumes, but removing one side of let's say a cube of rock is also going to decompress it somewhat. This may cause generation of magma. No worries though - I don't see any reason why it should rise to the surface. If anything at all, it's going to fall down through the hole (but not much, see above). Also, decompression may cause release of volatiles or gas, the most common being CO2 and H2O I guess, also H2S or SO2 depends exactly what is down there. Also, the movement of rocks in an area of the Earth that's not ductile anymore but rather brittle (lithosphere) is sure to cause some earthquakes. Are there earthquakes going to be dangerous for anyone? I don't know.

What would this hole look like if you peeked down? My guess that it will be filled with water. If this hole starts at the ocean, then the ocean will just flow inside and fill it. It is possible that some mega waves or tsunamis will accompany it. It will pour down until it either meets the closed rock, or just evaporates. Remember - it's pretty hot down there. It will evaporate and rise, then cool and starts raining down again and you will have a nice convective cell in the upper few kilometers of this hole.

In contrast, if this was not in the ocean but rather on land, groundwater will fill it in. I guess most of the earth has groundwater (maybe except the large deserts, but even there some water exists) that will just flow inside and create a similar convective cell.

i think that we simply do not have enough data on earth what would happen. and if such a task were even possible. as depicted by the movie The Core, there could be a crystallized structure between the core and the surface thats even impossible to dig through by conventional means. it would sound logical, given that there simply is that much pressure going on to make crystals, that an entire part of earth is made out of crystal. plus the constant shift of the earth's plates would also mean that the tunnel dug behind you would be closed off immediatly.

right now, the diagram shown above is still pure guess work. same as how the sun works, how black holes are working. we know how a bird flies and how to make electricity because we can experience it. but we havnt experienced going to the center of the earth, so we dont know yet how it works.