Posts Tagged ‘Earth’

Man-made global warming is just presumption

December 18, 2013

Presumptions, presumptions everywhere but no evidence to be seen.

  1. There is a presumption among the global warming orthodoxy – but no evidence – that increasing carbon dioxide concentrations in the atmosphere causes significant warming of the Earth’s surface.
  2. There is a presumption that carbon dioxide emissions from human activities (primarily by the increase in fossil fuel combustion since the 1950’s) is the primary cause of the increase of concentration in the atmosphere. This presumption is based on the assumption that the oceans and the forests absorb just as much carbon dioxide as they emit. This balance is an assumption and is based on the argument that pre-industrial concentrations of carbon dioxide in the atmosphere were largely constant. The actual emissions from the forests and the oceans are each an order of magnitude greater than man-made emissions of carbon dioxide. The margin of error in the estimates of amounts of carbon dioxide emitted (and absorbed) by the oceans and the forests is greater than the emissions from fossil fuel combustion. The emissions due to volcanic activity are not well understood just as the rate at which  carbonate sediments are laid down by the oceans is unknown (which in turn affects the concentration of what is dissolved in the oceans and therefore how much gets absorbed by the oceans from the atmosphere). Carbon dioxide released or absorbed by tectonic activity is unknown. There is a presumption based on some limited evidence that approximately 40% of what is released by fossil combustion is accumulating as atmospheric concentration. There is no presumption, however, that increasing carbon dioxide concentration in the atmosphere must lead to an increased absorption rate.
  3. Fossil fuel combustion and man-made carbon dioxide emissions as well as the atmospheric concentration have been increasing at least since about 1950. For the last 17 years this increase has continued but global temperatures have not increased. For the last 10 years the global temperature has shown a slight decline. It is therefore presumed that the original presumption still holds and that the extra heat is presumed to be hidden in a variety of places  (the deep oceans for example) other than at the Earth’s surface. There is no presumption that these observations are fundamentally in conflict with the original presumption.
  4. It is entirely logical that warming of the earth will cause the ice caps to melt and sea levels to rise just as global cooling will cause the ice sheets to expand and the sea levels to fall. It is presumed by the “establishment” that observed short-term reductions of ice extent are not due to natural variation but are proof that man-made global warming prevails. But when ice extent increases – as is happening currently – it is presumed to be due to natural variability and not relevant to the underlying trend due to man-made global warming.
  5. It is postulated by the establishment that extreme weather events are more likely to occur due to man-made global warming (and are not due to natural variability). But when extreme weather events show a decline – as they are doing currently – then any such decline is presumed to be due to natural variability.
  6. A preponderance of “cold records” being broken – rather than “heat records” is presumed to be proof of man-made global warming causing extreme weather events.

Presumptions do not a science make – especially when the evidence available increasingly conflicts with the presumptions.

MOM turns its camera on Earth while preparing for critical insertion into Mars trajectory

November 21, 2013

While the MOM spacecraft “Mangalyaan” is in orbit around Earth, its systems and scientific instruments are being tested to prepare for the critical burn at 0036 IST on 1st December (1906 GMT 30th November) to inject it into a Mars trajectory. The colour camera has been turned on Earth during testing and ISRO has released this photograph.

This image was taken yesterday at around 1350 hrs (IST) from a height of almost 70,000 km above earth and has a spatial resolution of 3.5 km.

Earth from MOM 20131120 image ISRO

Earth from MOM 20131120 image ISRO

The spacecraft’s engine has so far been fired as follows:

  • first orbit-raising manoeuvre 416 seconds
  • second orbit raising manoeuvre 570.6 seconds
  • third orbit raising manoeuvre 707 seconds
  • fourth orbit-raising manoeuvre (time not specified, firing curtailed inadvertently)
  • fourth supplementary orbit raising manoeuvre 303.8 seconds
  • fifth orbit raising manoeuvre 243.5 seconds

The next critical burn (the seventh) has to to use the 440 Newton liquid engine again to impart a delta-v of nearly 648 m/s and the engine will have its longest burn time of 1,351 seconds. Three mid course corrections on the spacecraft’s journey to Mars are planned for and the fuel carried has to also cater for finally braking to enter into Mars orbit.

The Hindu carries a long, fascinating interview with  K. Radhakrishnan, ISRO Chairman. The article is a little unusual in its length and technical detail which most Indian newspapers would fight shy of! Some selected extracts below but the entire interview is worth reading:

After the Polar Satellite Launch Vehicle (PSLV-C25) put India’s Mars Orbiter into a perfect earth-bound orbit on November 5, it has been a smooth journey so far for the spacecraft. The Indian Space Research Organisation (ISRO) boosted the Mars Orbiter’s apogee in six complex manoeuvres executed between November 7 and 16. ISRO did this by giving commands from the ground to the spacecraft’s propulsion system, called 440 Newton engine, to fire. A crucial event of the trans-Mars injection of the spacecraft will take place on December 1 by a prolonged firing of the 440 Newton engine.

…. Till now, we have completed six manoeuvres including a supplementary one. Currently, the spacecraft’s apogee is 1,92,915 km. 

In the early hours of December 1, around 00.36 hours, we have the trans-Mars injection of our Mars spacecraft. On that day, we are going to use the 440 Newton liquid engine again to impart a delta-v, that is, an incremental velocity of nearly 648 metres a second to the spacecraft and the engine will burn for 1,351 seconds. It is crucial in the sense that we need to give the exact velocity required to take the spacecraft from the earth-orbit, passing through the sphere of influence of the earth which extends up to 9.25 lakh km from the earth, cruise through the long helio-centric phase, then get into the sphere of influence of Mars, and on its arrival near Mars on September 24, 2014, it has to be put into 376 km plus or minus 50 km above Mars at that point of time. On the same day, the next crucial operation of the spacecraft’s Mars orbit insertion has to take place. When this running of the 440 Newton liquid engine takes place on December 1, we also have eight numbers of 22 Newton control thrusters firing. 

There are two tasks for them. One is the spacecraft’s attitude control. Secondly, if it is required, they will aid the 440 Newton thrusters to augment its thrust-level. Both the functions will be performed and the Mars spacecraft will then be moving towards the helio-centric orbit. Then on December 11, we plan to have one small firing for mid-course correction of the spacecraft. There may be one more mid-course correction during the helio-centric phase, and subsequently, a fortnight before the spacecraft’s arrival near Mars, there will be one more mid-course correction. So there will be three mid-course corrections between December 1, 2013 and September 24, 2014. 

With the velocity imparted to the spacecraft on December 1, 2013, we will have an estimate of its expected position on September 24, 2014. We will be continuously tracking the spacecraft and if there are deviations vis-à-vis the end goal, we will make the corrections. So December 1 will be a crucial operation. The spacecraft’s propulsion system, i.e., the 440 Newton liquid engine, will complete its first phase of operations on December 1. It has to be re-started for its operation on September 24. There is thus a long gap. 

How confident are you that you can re-start the 440 Newton engine after it has hibernated in deep space for about 300 days during the spacecraft’s voyage? 

We have been using the 440 Newton engine for our Geo-synchronous Satellite – GSAT- missions where the spacecraft’s orbit has to be raised about a week after its launch. In the case of Chandrayaan-1, we had to restart the operation after a fortnight. For that, we had qualified the liquid engine in 2008 to restart after one month. 

During the last two years, considering the specific requirements of our Mars Orbiter Mission for re-starting the spacecraft’s 440 Newton engine after it has idled for about 300 days, we had done these two actions. One is we have provided a set of parallel circuits for the propellants’ flow-lines and also provided redundancy in the form of a latch-valve. So what essentially happens is that one portion of the fluid circuit will be closed after December 1. The parallel path will be energised for the operation in September 2014. 

……. In the spacecraft’s orbit-raising manoeuvres, during its trans-Mars injection and its insertion into the Martian orbit, the firing of the liquid engine is done in a closed loop mode. Here, a precision accelerometer is used to estimate the incremental velocity added as the liquid engine burns and when the accelerometer gives a feedback that the required incremental velocity added to the spacecraft has been achieved, the burning of the liquid engine is automatically terminated. So, minor variations in the performance of the liquid engine will not matter because we are cutting off its burning based on the delta-v that is achieved. That is why we call it closed loop of firing. …… 

Up to (925,000) km from the Earth, the spacecraft will be in the sphere of influence of the Earth. Subsequently, it will be moving into the helio-centric phase of its flight. It is a long one, where you have to look at the influence of other planets and the Moon and then the solar radiation pressure acting on the spacecraft. That pressure varies with respect to time because the geometry of the sun and the spacecraft matters here. This is something we have not done so far and this helio-centric phase of the flight is new to us. 

In Chandrayaan-1, we had travelled up to (400,000) km, which was well within the sphere of influence of the Earth. But here for the first time, we are moving out of the sphere of influence of the earth. So how the spacecraft will behave during the helio-centric flight of 680 million km along the arc is new to us. Then the spacecraft gets into the sphere of influence of Mars which is nearly six lakh km from Mars. 

From our understanding of the Mars gravity model, the influence of the atmosphere of Mars, the influence of the two satellites of Mars and the solar radiation pressure there on the spacecraft are very important. This is also a new thing that we are attempting. 

So the navigation of the Mars spacecraft from the orbit of the Earth to the orbit of Mars, passing through all these three phases, is a new knowledge that we are acquiring and validating during the next 300 and odd days.

Read the whole article.

400m asteroid (2013 TV135) could collide with Earth on 26th August 2032

October 18, 2013

Not quite another doomsday prediction but the Russian Vice Premier Dmitry Rogozin was moved to tweet about the threat to blow up the Earth.

Ria Novosti: 

Ukrainian astronomers have discovered a large asteroid that could hit Earth in 2032, though the impact risk is minimal, according to current estimates.

The 410-meter-wide (1,350-foot) minor planet, which has been named 2013 TV135, was first discovered last weekend by the Crimean Astrophysical Observatory in southern Ukraine, according to the International Astronomer Union’s Minor Planet Center.

As of Thursday, the discovery had been confirmed by five more astronomy groups, including in Italy, Spain, the UK and Russia’s Siberian republic of Buryatia, the center said on its website.

The asteroid has been classified as potentially hazardous, a formal tag given to celestial bodies whose orbits bring them closer than 7.5 million km from Earth’s orbit. The minimal distance between the orbits of 2013 TV135 and Earth is currently put at 1.7 million km.

However, it also has a 1 in 63,000 chance of colliding with Earth on August 26, 2032, according to available estimates.

“Here’s a super-task for our space industry,” Russian Deputy Prime Minister Dmitry Rogozin, who has lobbied for Russia to develop asteroid defense systems, said of the asteroid on Twitter on Thursday.

The 2013 TV135 has been given a 1 out of 10 rating on the Torino Scale, which estimates asteroid impact hazards. Only one other asteroid currently has the same rating, with collision risks for all others being “effectively zero,” according to NASA’s Near Earth Object Program.

The 2013 TV135 colliding with Earth would create an explosion estimated to be equivalent to 2,500 megatons of TNT – 50 times greater than the biggest nuclear bomb ever detonated.

Asteroids due to pass close to Earth in the next 200 years are shown in this graphic:

Asteroids That Buzz Planet Earth

Asteroids which will come closest to the Earth in the next 200 years

 

The lunar nodal cycle and its effects on climate

July 27, 2013

A paper has just been published in the International Journal of Climatology showing that the lunar nodal cycle influences “the low-frequency summer rainfall variability over the plains to the east of subtropical Andes, in South America, through long-term sea surface temperature (SST) variations induced by the nodal amplitude of diurnal tides over southwestern South Atlantic (SWSA).”

Eduardo Andres Agosta, The 18.6-year nodal tidal cycle and the bi-decadal precipitation oscillation over the plains to the east of subtropical Andes, South America, International J of Climatology, DOI: 10.1002/joc.3787

Abstract: This work shows statistical evidence for lunar nodal cycle influence on the low-frequency summer rainfall variability over the plains to the east of subtropical Andes, in South America, through long-term sea surface temperature (SST) variations induced by the nodal amplitude of diurnal tides over southwestern South Atlantic (SWSA). In years of strong (weak) diurnal tides, tide-induced diapycnal mixing makes SST cooler (warmer) together with low (high) air pressures in the surroundings of the Malvinas/Falklands Islands in the SWSA, possibly through mean tropospheric baroclinicity variations. As the low-level tropospheric circulation anomalies directly affect the interannual summer rainfall variability, such an influence can be extended to the bi-decadal variability present in the summer rainfall owing to the nodal modulation effect observed in the tropospheric circulation. The identification of the nodal periodicity in the summer rainfall variability is statistically robust.

The lunar nodal cycle is not something that is very well known but it is another celestial cycle which is clearly not to be ignored. Naturally the IPCC takes no notice of solar cycles, planetary cycles or lunar cycles and all these are lumped into what could be considered “natural variability”.

(Sourced from Wikipedia)

The lunar orbit is inclined by about 5 degrees on the ecliptic. The moon  therefore can lie up to about 5 degrees north or south of the ecliptic. The ecliptic is the plane of the apparent path of the Sun on the celestial sphere, and is coplanar with both the orbit of the Earth around the Sun and the apparent orbit of the Sun around the Earth.

File:Lunar eclipse diagram-en.svg

Lunar eclipse orbital diagram: wikipedia

The lunar nodes precess around the ecliptic, completing a revolution (called a draconitic or nodical period, the period of nutation) in 6793.5 days or 18.5996 years.

The effects of the 18.6 year lunar nodal cycle on climate on tides and geological sediments and on weather and climate have long been of interest (though not apparently for the IPCC).

Nanocycles Method is the English translation of the title of a book published in Russian by Professor of Geology S Afanasiev of Moscow University in 1991,ISBN 5–7045–0109–0.

From “Nanocycles Method” by S Afanasiev, 1991

The lunar node cycle, which is presently 18.6 years, affects the rainfall on a 9.3 year cycle and this shows up as varying thickness layers of deposits, or varves, in geological formations. 

However the moon’s orbit is gradually getting larger over time and so its period is slowing down. The rate of movement of the nodes is also decelerating and Prof Afanasiev has determined the accurate nodal cycle period for the whole of the last 600 million years.

The cycle of the lunar node is important in affecting the weather because it plays a part in determining tides in the atmosphere, oceans and solid body of the earth. The atmospheric tides affect rainfall which in turn affects river flows and hence the deposition of geological varves, or annual deposits in geological layers. ….. 

At the present time, with a nodal cycle of 9.3 years, successive nodal cycles begin 0.3 years later in the seasons each cycle. Therefore after 3 or 4 cycles the nodal cycle start return to the same time of year again. The average period of the cycle when the nodal cycle comes at the same time of year is 9.3/0.3 or 31 years. Specific occurrences of nearly the same season, within 0.1 year, will occur after 28, 65 and 93 years and so on. 

…. Because the lunar nodal cycle period has changed from 9.147 years to 9.298 years in the last 1.0 million years, the secondary cycle has varied from 62.12 years to 31.21 years. If this cycle can be measured in a deposit to an accuracy of 1 year then it allows the dating of the deposit to an accuracy of +/-0.03 million years.

A small selection of papers dealing with the effects of the 18.6 year lunar nodal cycle is given below:

The climate is a-changin

April 20, 2013

The winds of climate are changing direction – again.

Forty years ago “climate scientists” were sure we were entering a new ice age and even that we could have triggered the end of the current inter-glacial.

For forty years we have seen the growth of the global warming meme and the demonisation of carbon dioxide and of all things “fossil”.

A new economy based on the expensive and premature cessation of the use of fossil fuels took shape. All alternatives to fossil fuel – no matter how expensive or impractical – were worthy of subsidy. By invoking a connection to global warming any science project could attract funds. A fascist and authoritarian “environmental” politics gained ground.  The politicians had a new “label” for introducing taxation in the name of controlling climate (!). Vast new revenue streams of taxes and subsidies and carbon credits were created in the name of protecting the planet. In fact the penalty for not being “politically correct” on climate was seen as being so disadvantageous that every product – from toothpaste to children’s toys to aircraft and weapons – had to show that it was “climate-smart”. Meaningless new parameters like “carbon footprint” entered the vocabulary. No self-respecting newspaper or scientist or politician or business could afford to be heretical with respect to the new religion of the day.

But the Earth and the Sun and the resulting climate pay little attention to the puny efforts of man and dance to their own music. When an ice age is to come it will come and when the ice sheets are to retreat the earth will warm and humanity’s best option is to adapt to the changes as they come. If we understand anything about the Sun and its cycles, an ice age will surely come – whether in 10 or 10,000 years.  And we should concentrate on having the wherewithal to cope when it does. To attempt to control the climate has more than a hint of arrogance. We might as well try to ask the Sun to shine a little less brightly or for a little longer!

But for the last 17 years (or 12 or 18 depending upon how religious one is) global warming has stalled. Now vast amounts of a “new” fossil fuel – shale gas –  have been discovered and its utilisation is changing the economic landscape. “Global warming” was renamed to be “climate change”. The money making (for some) revenue schemes and subsidy-milking for unnecessary and expensive renewable energy have been revealed for the scams they are. Heretical views are being expressed again.

The climate winds are changing:

  1. The Great Green Con no. 1: The hard proof that finally shows global warming forecasts that are costing you billions were WRONG all along   
  2. A sensitive matter
  3. Spiegel Stops Believing…”Hot Debate Over Climate: How Reliable Are The Prognoses?” Growing Doubts Over Models! 

  4. Global warming: time to rein back on doom and gloom?
  5. Climate scientists struggle to explain warming slowdown 

  6. Mother Of German Green Weeklies, Die Zeit, Shocks Readers…Now Casts Doubt On Global Warming!

Could solar flare last week be linked to two major earthquakes yesterday?

April 17, 2013

Like primitive man I am overwhelmed by the power of the Sun and a firm believer that even minute solar effects can have a major effect on the Earth and its systems. (I also note that my deification of the Sun must be similar to that by our ancient ancestors and is probably not unconnected to my moving to Scandinavia). In any case I am convinced that for climate

“Solar effects are much more profound than many so-called climate scientists like to admit”,

but I am not sure how strong the link to earthquakes is.

The link between solar effects (radio flux, sunspots, magnetic reversals, proton events….) and volcano activity and earthquakes has been postulated and studied many times but if any such link does exist it is not something obvious and it is by unknown mechanisms. For some this search for such a link is not “science” and there is no link. For others it can be a lifetime’s quest. But “intuition” and “gut-feeling” keeps me believing that there must be a connection. It could well be that the build-up of stresses upto some “breaking point” within the earths crust are a result of ongoing geologic processes and do not need any external trigger like solar activity or the position of the planets to be unleashed. But even continental drift and the build-up of seismic or volcanic stresses are all – ultimately – driven by energy fluxes. And all energy fluxes on Earth can eventually be traced to the Sun (except perhaps if the energy is from any ongoing nuclear reactions in the Earth’s core).

There were two major earthquakes yesterday – USGS

  1. 6.6, 23km ESE of Aitape, Papua New Guinea, 2013-04-16 22:55:27 UTC, 13.0 km deep
  2. 7.8, 83km E of Khash, Iran, 2013-04-16 10:44:20 UTC, 82.0 km deep

And – I note in passing – on April 11th – 5 days ago there was a solar flare and a Coronal Mass Ejection (CME) event. Could be just a coincidence of course – but perhaps not …

Discovery News: APR 11, 2013 03:00 PM ET

The sun has unleashed the biggest solar flare of the year, quickly followed by an Earth-directed coronal mass ejection (CME). Both phenomena have the potential to impact communications and electronics on Earth and in orbit.

Although the sun is currently experiencing “solar maximum” — the culmination of its approximate 11-year cycle — scientists have noted that this particular maximum is a lot quieter than predicted. At this time, the sun should be bubbling with violent active regions, exhibiting sunspots, popping off flares and ejecting CMEs. But so far, the sun seems to be taking it relatively easy.

This morning (at 0716 UT), active region (AR) 1719 erupted with an M-class flare. With a rating of M6.5, this event is the most energetic flare of 2013 (although it’s a lot less impressive than 2012′s X-class fireworks). What’s more, the site of the explosion unleashed a CME in our direction.

A CME is a magnetic ‘bubble’ containing high-energy solar particles. When the CME hits Earth’s global magnetic field, it may align just right to generate a geomagnetic storm. Should this happen, we’ll be able to measure the extreme magnetic distortion of the magnetosphere and bright aurorae at high latitudes may result. Aurorae are caused when solar particles are injected into the polar regions via the Earth’s magnetic field — the particles then collide with atmospheric gases, generating a beautiful light display.

This morning’s CME was clocked traveling at a breakneck speed of 600 miles per second — at that rate it should hit Earth in the early hours of Saturday morning (April 13).

Shortly after the M-class flare erupted, a weak solar energetic particle (SEP) event was detected. This “radiation storm” was the result of relativistic particles slamming into the Earth’s upper atmosphere originating from the flare site.

Image: NASA’s Solar Dynamics Observatory captured this image of an M6.5 class flare at 3:16 EDT on April 11, 2013. This image shows a combination of light in wavelengths of 131 and 171 Angstroms. Credit: NASA/SDO

Noted in passing 5th January 2013

January 5, 2013

Wildlife gallery from Greenland: Photo: Uri Golman

A stunning gallery of wildlife pictures from Greenland.

In the ever-changing world of the web and personal computing, a reminder of the MS wrist-watch and other 10 EPIC CES fails.

Science Fraud – Another web-site silenced by legal threats and the University of Regensburg has rescinded the doctorate of a dentist who had submitted a dissertation that was essentially that of her husband’s.

A new open-access paper in Earth System Dynamics showing that recent global warming is not statistically significantly related to anthropogenic forcing. Matt Ridley has 2 interesting pieces on how fossil fuels have actually greened the planet and how Europeans seem intent on making their future as bad as they can.

A new kidney transplantation racket revealed in India where the price of a kidney varies between Rs. 70,000 and 300,000 ($1,400 to $6,000). Indian Supreme Court reacts to over 2,200 deaths in clinical trials carried out by international pharmaceutical companies in India.

Some modern humans who live natural lifestyles in the forests of Earth still climb more or less like a chimpanzee and ‘Lucy’ could climb like chimpsJumping genes and horizontal gene transfer leads to the conclusion that cows are more closely related to snakes than to elephants!

Wallace’s letter to Darwin in 1864 doubting the assertion that the aristocracy are more beautiful than the middle-classes. Lead concentration in Greenland ice shows that when Rome fell there was a real reduction of industrial activity which lasted almost a millenium. It could be that climate change is not the great destroyer but is the great enabler and that many of the evolutionary developments of modern humans have been driven by natural – and rapid – climate change. Archaeological sleuthing sheds more light on the strange goings-on during the mutiny on the VOC Retourschip Batavia, in 1629.

Visibility of the Venus transit today and tomorrow

June 5, 2012

WARNING!

Direct viewing of the Sun with the naked eye or through open telescopes or binoculars should be avoided. Indirect observation of a projected image is advised.

Transit times

Venus transit 5th-6th June 2012: image BBC

BBC: Venus transits occur four times in approximately 243 years; more precisely, they appear in pairs of events separated by about eight years and these pairs are separated by about 105 or 121 years. The reason for the long intervals lies in the fact that the orbits of Venus and Earth do not lie in the same plane and a transit can only occur if both planets and the Sun are situated exactly on one line.

This has happened only seven times in the telescopic age: in 1631, 1639, 1761, 1769, 1874, 1882 and 2004. Once the latest transit has passed, the next pair will not occur until 2117 and 2125. Most people alive today will probably be dead by then.

Earthhour is not for me – It is a tale told by idiots..

March 31, 2012

I shall not be trying to switch off today. But I shall not either be trying to maximise my electricity consumption in some futile gesture to protest against the even more idiotic gesture that is Earthhour. I shall be as normal as possible.

The hype around Earthhour on 31st March each year is not just irritating – it demonstrates for me the intellectual bankruptcy that is now enveloping the environmentalists and conservationists and the eco-fascists. It is a tale told by idiots and full of sound and fury and signifying – nothing.

If it was a just a meaningless gesture it would not be as bad as it is. It actually denies all that humankind has achieved and promotes a view of what the future should be which not only do I  not share but is one which celebrates the lack of electricity. It condemns humankind to return to a bleak world of hunger and death and misery. That may be a future which the lack of electricity could cause but it is not a future I would choose or glorify.

This post by Ross McKitrick is pretty close to how I see things:

Earth Hour: A Dissent

by Ross McKitrick

Ross McKitrick, Professor of Economics, Univer...

Ross McKitrick, Professor of Economics, University of Guelph, Canada. (Photo credit: Wikipedia)

Ross McKitrick, Professor of Economics, University of Guelph, Canada. (Photo credit: Wikipedia)

In 2009 I was asked by a journalist for my thoughts on the importance of Earth Hour.

Here is my response.

I abhor Earth Hour. Abundant, cheap electricity has been the greatest source of human liberation in the 20th century. Every material social advance in the 20th century depended on the proliferation of inexpensive and reliable electricity.

Giving women the freedom to work outside the home depended on the availability of electrical appliances that free up time from domestic chores. Getting children out of menial labour and into schools depended on the same thing, as well as the ability to provide safe indoor lighting for reading.

(more…)

Diamonds from the deep: Carbon cycle extends down to earth’s lower mantle

September 16, 2011
S-waves do not pass through the Earth's core, ...

Image via Wikipedia

What we know about the layers forming the interior of the earth are mostly inferred from mapping the propagation and refraction of earthquake waves. The earth’s lower mantle starts some 700km down and extends to a depth of about 2900km. The upper and lower mantle demonstrate – in fluid dynamic terms – a viscous chaotic flow but the mechanisms by which material is exchanged between the upper and lower mantle are not fully understood.

Science Daily: Michael Walter of the University of Bristol and colleagues in Brazil and the United States analyzed a set of “superdeep” diamonds from the Juina kimberlite field in Brazil. Most diamonds excavated at Earth’s surface originated at depths of less than 200 kilometers. Some parts of the world, however, have produced rare, superdeep diamonds, containing tiny inclusions of other material whose chemistry indicates that the diamonds formed at far greater depths

M. J. Walter, S. C. Kohn, D. Araujo, G. P. Bulanova, C. B. Smith, E. Gaillou, J. Wang, A. Steele, S. B. Shirey. Deep Mantle Cycling of Oceanic Crust: Evidence from Diamonds and their Mineral Inclusions. Science, 2011; DOI: 10.1126/science.1209300

ABSTRACT

A primary consequence of plate tectonics is that basaltic oceanic crust subducts with lithospheric slabs into the mantle. Seismological studies extend this process to the lower mantle, and geochemical observations indicate return of oceanic crust to the upper mantle in plumes. There has been no direct petrologic evidence, however, of the return of subducted oceanic crustal components from the lower mantle. We analyzed superdeep diamonds from Juina-5 kimberlite, Brazil, which host inclusions with compositions comprising the entire phase assemblage expected to crystallize from basalt under lower mantle conditions. The inclusion mineralogies require exhumation from the lower to upper mantle. Because the diamond hosts have carbon isotope signatures consistent with surface-derived carbon, we conclude that the deep carbon cycle extends into the lower mantle.

“This study shows the extent of Earth’s carbon cycle on the scale of the entire planet, connecting the chemical and biological processes that occur on the surface and in the oceans to the far depths of Earth’s interior,” according to Nick Wigginton, associate editor at Science.

The carbon cycle generally refers to the movement of carbon through the atmosphere, oceans, and the crust. Previous observations suggested that the carbon cycle may even extend to the upper mantle, which extends roughly 400 kilometers into Earth. In this region, plates of ocean crust — bearing a carbon-rich sediment layer — sink beneath other tectonic plates and mix with the molten rock of the mantle.

Seismological and geochemical studies have suggested that oceanic crust can sink all the way to the lower mantle, more than 660 kilometers down. But actual rock samples with this history have been hard to come by

File:Slice earth.svg

Schematic view of the interior of Earth. 1. continental crust - 2. oceanic crust - 3. upper mantle - 4. lower mantle - 5. outer core - 6. inner core - A: Mohorovičić discontinuity - B: Gutenberg Discontinuity - C: Lehmann discontinuity: image Wikipedia

PhysOrg: The diamonds were analyzed for carbon at Carnegie. Four of the diamonds contained low amounts of carbon-13, a signature not found in the lower mantle and consistent with an ocean-crust origin at Earth’s surface. “The carbon identified in other super-deep, lower mantle diamonds is chiefly mantle-like in composition,” remarked co-author Steven Shirey  at Carnegie. “We looked at the variations in the isotopes of the carbon atoms in the diamonds. Carbon originating in a rock called basalt, which forms from lava at the surface, is often different from that which originates in the mantle, in containing relatively less carbon-13. These super-deep diamonds contained much less carbon-13, which is most consistent with an origin in the organic component found in altered oceanic crust.


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