Peatlands are carbon-rich ecosystems that cover just three per cent of Earth’s land surface, but store one-third of soil carbon. Peat soils are formed by the build-up of partially decomposed organic matter under waterlogged anoxic conditions. Most peat is found in cool climatic regions where unimpeded decomposition is slower, but deposits are also found under some tropical swamp forests. Here we present field measurements from one of the world’s most extensive regions of swamp forest, the Cuvette Centrale depression in the central Congo Basin.
“Earth grew by the accretion of meteoritic material. High-precision isotopic data reveal how the composition of this material changed over time, forcing revision of models of our planet's formation.
For more than half a century, scientists have estimated the bulk chemical composition of Earth by comparison with its potential cosmic building blocks, as sampled by meteorites. In a conceptual breakthrough, Dauphas uses the unique isotopic content of different types of meteorite to identify those that best represent these building blocks. The author also evaluates whether the material added to Earth during its formation changed over time. Fischer-Gödde and Kleine show that not even the most recently accreted 0.5% of such material consisted of the type of meteorite long thought to be a major contributor to our planet's composition. This realization challenges our understanding of how Earth obtained its inventory of volatile elements and water.
In the 1970s, Earth was shown to have a different oxygen-isotope composition from most meteorites. The only meteorites that have a similar oxygen isotopic abundance are called enstatite chondrites, which are silicon-rich and highly reduced (most iron is in the form of metal or sulfide, rather than oxide). This similarity drove several models that based Earth's composition on enstatite chondrites. However, the mismatch in the elemental composition between such meteorites and Earth's rocks led most researchers to continue using models based on more-oxidized and volatile-rich meteorites known as carbonaceous chondrites.
Improvements in the ability to determine precise isotopic abundances led to the discovery that many elements can be used to distinguish between Earth and meteorites. In 2011, a study of these isotopic differences suggested that Earth was made from a mixture of meteorite types, not just the carbonaceous chondrites that had been the main component of most models. Dauphas takes this approach further by developing a methodology in which the isotopic disparity between different groups of meteorites and Earth can be used to track the composition of the materials that accreted to our planet throughout its formation.
The most important chemical differentiation event in Earth's history was the separation of its iron-metal core from its silicate mantle. When the core formed, elements that are more soluble in metal than in silicate were selectively removed from the mantle. Some elements (such as iridium, platinum, palladium and ruthenium) are so soluble in metal that the mantle should have been effectively stripped of them during core formation. However, the observed abundances of these elements in the mantle are in the same relative proportion as those seen in primitive meteorites. Furthermore, they are depleted by a factor of only about 350 with respect to their abundance in meteorites, compared with the million-fold depletion that would be expected were the mantle in chemical equilibrium with the core.”
The Earth formed by accretion of Moon- to Mars-size embryos coming from various heliocentric distances. The isotopic nature of these bodies is unknown. However, taking meteorites as a guide, most models assume that the Earth must have formed from a heterogeneous assortment of embryos with distinct isotopic compositions. High-precision measurements, however, show that the Earth, the Moon and enstatite meteorites have almost indistinguishable isotopic compositions. Models have been proposed that reconcile the Earth–Moon similarity with the inferred heterogeneous nature of Earth-forming material, but these models either require specific geometries for the Moon-forming impact or can explain only one aspect of the Earth–Moon similarity (that is, 17O). Here I show that elements with distinct affinities for metal can be used to decipher the isotopic nature of the Earth’s accreting material through time. I find that the mantle signatures of lithophile O, Ca, Ti and Nd, moderately siderophile Cr, Ni and Mo, and highly siderophile Ru record different stages of the Earth’s accretion; yet all those elements point to material that was isotopically most similar to enstatite meteorites. This isotopic similarity indicates that the material accreted by the Earth always comprised a large fraction of enstatite-type impactors (about half were E-type in the first 60 per cent of the accretion and all of the impactors were E-type after that). Accordingly, the giant impactor that formed the Moon probably had an isotopic composition similar to that of the Earth, hence relaxing the constraints on models of lunar formation. Enstatite meteorites and the Earth were formed from the same isotopic reservoir but they diverged in their chemical evolution owing to subsequent fractionation by nebular and planetary processes.
"...Species naturally come and go over long periods of time. But what sets a mass extinction apart is that three-quarters of all species vanish quickly. Earth has already endured five mass extinctions, including the asteroid that wiped out dinosaurs and other creatures 65 million years ago. Conservationists have warned for years that we are in the midst of a sixth, human-caused extinction, with species from frogs to birds to tigers threatened by climate change, disease, loss of habitat, and competition for resources with nonnative species. But how does this new mass extinction compare with the other five?
Barnosky and colleagues took on this challenge by looking to the past. First, they calculated the rate at which mammals, which are well represented in the fossil record, died off in the past 65 million years, finding an average extinction rate of less than two species per million years. But in the past 500 years, a minimum of 80 of 5570 species of mammals have gone extinct, according to biologists' conservative estimates—an extinction rate that is actually above documented rates for past mass extinctions, says Barnosky. All of this means that we're at the beginning of a mass extinction that will play out over hundreds or thousands of years, his team concludes online today in Nature...."
New data from Curiosity has confirmed that the winds of Mars have been the primary force shaping the red planet’s landscape for billions of years.
The new data suggests that Mount Sharp once filled Gale Crater, and it was the winds that eroded it away to create the impression that it is the crater’s central peak. Instead it appears that it is the crater’s original floor!
Below the fold is the video from the link showing a number of dust devils imaged by Curiosity.
This link provides a gif animation showing the surprisingly significant changes to the ripples in the sand dunes directly below Curiosity that take place in only one day. The changes are astonishing, and show that even though Mars’ atmosphere is far thinner than Earth’s, it is capable of moving things quickly across the Martian surface.
On 14 February, the satellite company Planet, based in San Francisco, California, launched 88 shoebox-sized satellites in orbit. They joined dozens of others, bringing the constellation of “Doves,” as these tiny imaging satellites are known, to 144. Six months from now, once the Doves have settled into their prescribed orbits, the company says it will have reached its primary goal: being able to image every point on Earth’s landmass at intervals of 24 hours or less, at resolutions as high as 3.7 meters—good enough to single out large trees. It’s not the resolution that’s so impressive, though. It’s getting a whole Earth selfie every day.
“…A Trojan asteroid orbits the sun 60 degrees ahead of or behind a planet. Jupiter and Neptune have numerous Trojans, many of which have been in place for billions of years. These primordial rocks hold information about the solar system’s birth, and NASA has just announced plans to visit several of them in the 2020s and 2030s.
But Saturn and Uranus live in a rougher neighbourhood: the giant planets on either side of them yank Trojans away through their gravitational pull. So Saturn has no known Trojan, and Uranus had only one.
In July, though, astronomers reported a new asteroid, named 2014 YX49, that shares Uranus’s orbital period of 84 years. Now computer simulations of the solar system by brothers Carlos and Raul de la Fuente Marcos at the Complutense University of Madrid, Spain, indicate the asteroid is a Uranus Trojan. The simulations show that the asteroid has maintained its position ahead of Uranus for thousands of years….”
Scientists propose new planet definition that reinstates Pluto. Unhappy since 2006 with the definition of “planet” imposed by the International Astronomical Union (IAU) that demoted Pluto, planetary scientists, including New Horizons principal investigator Alan Stern, have now proposed a new definition that they think is more appropriate and would reinstate Pluto.
The scientists suggest planets should constitute as “round objects in space that are smaller than stars,” thus excluding white dwarfs, neutron stars, and black holes from the planetary status. “A planet is a sub-stellar mass body that has never undergone nuclear fusion and that has sufficient self-gravitation to assume a spheroidal shape adequately described by a triaxial ellipsoid regardless of its orbital parameters,” the proposal elaborates, noting that the Earth’s moon would constitute as a planet under the new definition.
Stern and his colleagues note that the IAU’s definition of a planet is too narrow and recognizes planets only as objects that orbit our sun and “requires zone clearing, which no planet in our solar system can satisfy since new small bodies are constantly injected into planet-crossing orbits.”
Make sense to me as well as a lot of people. The definition created in 2006 was never very satisfactory, and I know many planetary scientists who have never accepted it.
"...I had spent an hour or two in Deline back in 2014, as an American diplomat posted to Canada. It was July and the lake was ice-free, endless and flat to the horizon. During my three-year tour, it was the sole time I needed a translator, because many Deline elders speak only their own language, North Slavey.
This past November, I returned to Deline to learn more about the community’s relationship with the lake, to witness the interplay of culture, language, wilderness and isolation that makes this area so distinct.
It was late afternoon when the small plane dipped through a thick, low-lying cloud layer and I saw boreal forest — part of a vast biome that stretches across northern North America and Eurasia — as far as the eye could see. The plane descended toward a slender strip covered in white, Deline’s single runway. It was a short drive from the airport to the hotel where I was staying, the community-owned Grey Goose Lodge. For such a tiny community, Deline has more tourist infrastructure than I expected, including a small handicrafts store in the hotel and an ambition to welcome the growing number of tourists who travel to Canada’s north for a winter and wilderness experience...."
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"... Comet Siding Spring passed extremely close to Mars on 19 October 2014 at 18:28 ± 0:01 UTC. Initial observations by Leonid Elenin on 27 February 2013, suggested that it might pass 0.000276 AU (41,300 km; 25,700 mi) from the center of Mars. With an observation arc of 733 days, the nominal pass is 0.000931 AU (139,300 km; 86,500 mi) from the center-point of Mars and the uncertainty region shows that it would not come closer than 0.000927 AU (138,700 km; 86,200 mi).
For comparison, Mars's outer moon Deimos orbits it at a distance of 0.00016 AU (24,000 km; 15,000 mi). Due to the uncertainty region, there was the possibility that it could pass Mars as far away as 0.000934 AU (139,700 km; 86,800 mi). It passed Mars at a relative velocity of 56 km/s (35 mi/s). As seen from Mars, C/2013 A1 peaked at approximately apparent magnitude −6.
"...The main body of the comet's tail is projected to miss Mars by some 10 Mars diameters. As a result, only higher-than-average-velocity meteoroid dust, ejected earlier in the approach of the comet, allow for impacts on Mars, its moons, and orbiting spacecraft. Dust particles ejected from the nucleus of the comet, at more than double the expected velocity when the comet was 3 AU from the Sun, could reach Mars approximately 43 to 130 min after the closest approach of the comet.There is a possibility for millimeter- to centimeter-size particles released more than 13 AU from the Sun, however, this is considered unlikely,although massive ejections from farther out have been deduced.
In 2013 it was thought possible that Comet Siding Spring would create a meteor shower on Mars or be a threat to the spacecraft in Mars orbit. Studies in 2014 showed the threat to orbiting spacecraft to be minimal. The greatest threat would be about 100 minutes after closest approach. Mars passed about 27,000 km (17,000 mi) from the comet's orbit around 20:10 UT.
The coma of the comet is projected to more than double the amount of hydrogen in the high atmosphere for a period of several tens of hours and to warm it by about 30 K for a few hours—the combination increasing the effect of atmospheric drag on the Mars Reconnaisance Orbiter and MAVEN spacecraft causing a measurable increase in orbital decay because of atmospheric ram pressure. These spacecraft will be approaching Mars to minimum altitudes of 250 km and 150 km and orbital periods of 3 and 4 hours, respectively. The amount of drag cannot be narrowed down greatly until the production rate of the comet is known, but it could be from 1.6 to 40 times normal drag. MAVEN, in particular, also has instruments to observe any changes to the gas composition of the atmosphere. The closest orbiting moon of Mars, Phobos, orbits far higher, at a minimum distance of 9,234.42 km (5,738.00 mi), more than 10 times the height of Mars's atmosphere.
Estimates for the diameter of the nucleus have varied from 1 to 50 km (1 to 31 mi), but now the nucleus is known to be only approximately 400–700 meters (0.2–0.4 mi) in diameter, roughly the diameter of asteroid 2010 XG11 that approached Mars on 29 July 2014. Based on early upper-limit size estimates, the resulting upper-limit energy of a hypothetical impact with Mars was 24 billion megatons. The diameter of such a hypothetical impact crater would be roughly ten times the diameter of the comet's nucleus. A 700-meter impactor would create around a 7–10 km (4–6 mi) crater.
The odds of an impact with Mars were 1 in 1250 in March 2013, 1 in 2000 in late March 2013, 1 in 8000 by April 2013, and 1 in 120,000 by 8 April 2013. The 8 April 2013 JPL Small-Body Database 3-sigma solution was the first estimate to show that the minimum approach by Comet Siding Spring would miss Mars.
Maven detected an intense meteor shower. Comet Siding Spring has a rotation period of approximately 8 hours. Debris from Comet Siding Spring added a temporary, but strong layer of ions to Mars's ionosphere (the first time such a phenomenon has been observed on any planet), and a few tons of cometary dust were vaporized high in Mars's atmosphere. Magnesium, iron, and other metals were observed to have had been deposited. An observer on the surface would have seen a few tens of meteors during the plane crossing.
During the flyby of Mars at a proximity of 140,000 km, Comet Siding Spring's magnetic field, generated by its interaction with the solar wind, caused a violent turmoil that lasted for several hours, long after its flyby. Its coma washed over Mars with the dense inner coma, reaching or almost reaching the planet's surface. The cometary magnetic field temporarily merged with and overwhelmed Mars's weak magnetic field.
Centennial-scale Holocene climate variations amplified by Antarctic Ice Sheet discharge.
Proxy-based indicators of past climate change show that current
global climate models systematically underestimate Holocene-epoch
climate variability on centennial to multi-millennial timescales,
with the mismatch increasing for longer periods.
Proposed explanations for the discrepancy include ocean–atmosphere
coupling that is too weak in models, insufficient energy cascades
from smaller to larger spatial and temporal scales, or that global
climate models do not consider slow climate feedbacks related to
the carbon cycle or interactions between ice sheets and climate.
Such interactions, however, are known to have strongly affected
centennial- to orbital-scale climate variability during past
glaciations, and are likely to be important in future climate
change. Here we show that fluctuations in Antarctic Ice Sheet
discharge caused by relatively small changes in subsurface ocean
temperature can amplify multi-centennial climate variability
regionally and globally, suggesting that a dynamic Antarctic Ice
Sheet may have driven climate fluctuations during the Holocene.
We analyzed high-temporal-resolution records of iceberg-rafted debris
derived from the Antarctic Ice Sheet, and performed both high spatial-
resolution ice-sheet modelling of the Antarctic Ice Sheet
and multi-millennial global climate model simulations.
Ice-sheet responses to decadal-scale ocean forcing appear to be less important, possibly indicating that the future response of the Antarctic Ice
Sheet will be governed more by long-term anthropogenic warming
combined with multi-centennial natural variability than by annual
or decadal climate oscillations.
(Photo: What COSMOS 11494 likely looks like now: The massive galaxy M87 is the most spectacular example of an elliptical galaxy we can see from Earth. The most fascinating feature of this galaxy is its jet, which is visible in optical light as well as x-rays and radio emissions. The jet extends from the central supermassive black hole of the galaxy and reaches out about 5,000 light-years. As a true elliptical galaxy, M87 has no obvious dust lanes and very little evidence of star formation. It likely formed from a recent merger between two other galaxies. )
"..This high ratio means that the galaxy created all its stars in a cosmic eye-blink, before any iron-producing white dwarfs exploded. The growth spurt lasted only 100 to 500 million years.
“This galaxy just went off like crazy, and it had a huge vigorous star-forming period,” Kriek says. Then, for unknown reasons, COSMOS 11494 suddenly quit making new stars.
The galaxy’s stellar mass is five times the Milky Way’s, or about 320 billion solar masses. Divide that number by the duration of the star-forming spurt, and it suggests the galaxy once converted 600 to 3000 solar masses’ worth of gas into stars a year. That far exceeds the Milky Way’s current star formation rate of about 2 solar masses per year.
Chiaki Kobayashi at the University of Hertfordshire in Hatfield, UK, is excited by the finding but warns that it raises lots of problems. “For example, it doesn’t match with the current understanding of galaxy evolution,” she says...."
(Photo: This view of a Martian rock slab called "Old Soaker," which has a network of cracks that may have originated in drying mud, comes from the Mast Camera (Mastcam) on NASA's Curiosity Mars rover.
The location is within an exposure of Murray formation mudstone on lower Mount Sharp inside Gale Crater. Mud cracks would be evidence of a time more than 3 billion years ago when dry intervals interrupted wetter periods that supported lakes in the area. Curiosity has found evidence of ancient lakes in older, lower-lying rock layers and also in younger mudstone that is above Old Soaker.
Several images from Mastcam's left-eye camera are combined into this mosaic view. They were taken on Dec. 20, 2016, during the 1,555th Martian day, or sol, of Curiosity's work on Mars.
The Old Soaker slab is about 4 feet (1.2 meters) long. Figure 1 includes a scale bar of 30 centimeters (12 inches). The scene is presented with a color adjustment that approximates white balancing, to resemble how the rocks and sand would appear under daytime lighting conditions on Earth.
Malin Space Science Systems, San Diego, built and operates MAHLI. NASA's Jet Propulsion Laboratory, a division of the Caltech in Pasadena, California, manages the Mars Science Laboratory Project for the NASA Science Mission Directorate, Washington, and built the project's Curiosity rover.
For more information about Curiosity, visit
As Curiosity moves across the dust-shrewn dune-filled flats at the base of Mt. Sharp it has recently taken images of surface rocks that have cracks resembling those found from drying mud.
Scientists used NASA’s Curiosity Mars rover in recent weeks to examine slabs of rock cross-hatched with shallow ridges that likely originated as cracks in drying mud. “Mud cracks are the most likely scenario here,” said Curiosity science team member Nathan Stein. He is a graduate student at Caltech in Pasadena, California, who led the investigation of a site called “Old Soaker,” on lower Mount Sharp, Mars.
If this interpretation holds up, these would be the first mud cracks — technically called desiccation cracks — confirmed by the Curiosity mission. They would be evidence that the ancient era when these sediments were deposited included some drying after wetter conditions. Curiosity has found evidence of ancient lakes in older, lower-lying rock layers and also in younger mudstone that is above Old Soaker.
The rover is no longer on the floor the crater, but in the foothills at the base of Mt. Sharp. Thus, what we are likely looking at is evidence of the slow disappearance of the giant lake that scientists think once filled Gale Crater. These mud cracks suggest that the rover is now moving up out of the lake and through its margins.
I plan to do a rover update for both Curiosity and Opportunity tomorrow, so stay tuned.
“Tidal evolution of the Moon from a high-obliquity, high-angular-momentum Earth. In the giant-impact hypothesis for lunar origin, the Moon accreted from an equatorial circumterrestrial disk; however, the current lunar orbital inclination of five degrees requires a subsequent dynamical process that is still unclear.
In addition, the giant- impact theory has been challenged by the Moon’s unexpectedly Earth-like isotopic composition. Here we show that tidal dissipation due to lunar obliquity was an important effect during the Moon’s tidal evolution, and the lunar inclination in the past must have been very large, defying theoretical explanations.
We present a tidal evolution model starting with the Moon in an equatorial orbit around an initially fast-spinning, high-obliquity Earth, which is a probable outcome of giant impacts. Using numerical modelling, we show that the solar perturbations on the Moon’s orbit naturally induce a large lunar inclination and remove angular momentum from the Earth–Moon system.
Our tidal evolution model supports recent high-angular-momentum, giant-impact scenarios to explain the Moon’s isotopic composition and provides a new pathway to reach Earth’s climatically favourable low obliquity. “
The deep nitrogen-covered basin on Pluto, informally named Sputnik Planitia, is located very close to the longitude of Pluto’s tidal axis and may be an impact feature, by analogy with other large basins in the Solar System.
Reorientation of Sputnik Planitia arising from tidal and rotational torques can explain the basin’s present-day location, but requires the feature to be a positive gravity anomaly, despite its negative topography.
Here we argue that if Sputnik Planitia did indeed form as a result of an impact and if Pluto possesses a subsurface ocean, the required positive gravity anomaly would naturally result because of shell thinning and ocean uplift, followed by later modest nitrogen deposition.
Without a subsurface ocean, a positive gravity anomaly requires an implausibly thick nitrogen layer (exceeding 40 kilometres). To prolong the lifetime of such a subsurface ocean to the present day and to maintain ocean uplift, a rigid, conductive water-ice shell is required. Because nitrogen deposition is latitude-dependent, nitrogen loading and reorientation may have exhibited complex feedbacks.
"...What caused the drop in CO2 at the Eocene-Oligocene transition? Recently, there have been some tantalizing indications that tectonically driven gateway changes may have caused the CO2 changes. In early work, Zachos et al. found evidence for an increase in ocean productivity at the Eocene-Oligocene boundary, attributed to changes in ocean circulation and upwelling associated with the opening of the Tasman Seaway. Based on increased silicic acid use by diatoms in the Late Eocene, Egan et al. have suggested that deepening and/or widening of the Southern Ocean gateways increased the strength of the Antarctic circumpolar current and led to increased upwelling south of the polar front. The resulting increase in surface-water nutrient concentration could have led to diatom proliferation, more organic carbon burial, and hence CO2 drawdown.
A recent modeling study has also indicated that gateway changes could be important for the global carbon cycle. Using an Earth system climate model, Fyke et al. showed that the opening of Drake Passage can lead to an increase in Atlantic overturning circulation and a decrease in Pacific overturning circulation. As a result, the characteristic residence times in the two basins change, such that the Atlantic reservoir of dissolved inorganic carbon becomes smaller and that of the Pacific grows. The net effect is a global increase in the ocean carbon reservoir, and hence an increase in CO2 drawdown from the atmosphere.
Galeotti et al. now present sedimentological evidence from Antarctica that calls for a reinterpretation of the ice sheet history across the Eocene-Oligocene transition. Geochemical proxy records previously suggested that the early ice sheet was large and transient, perhaps reflecting an “overshoot” of the climate system in response to a rapid forcing. The ice sheet was thought to have retreated after this “Early Oligocene Glacial Maximum,” as climate feedback processes resulted in a new steady state with a smaller ice sheet. Instead, Galeotti et al. suggest that the early ice sheet did not reach the coast at the Ross Sea. Rather than retreating, it subsequently advanced, reaching the Ross Sea continental margin 32.8 million years ago. Galeotti et al. propose that the initial, smaller ice sheet was able to respond dynamically to local variations in insolation on the comparatively short time scales of orbital precession and obliquity changes (tens of thousands of years). Once it reached the continental margin, it became relatively insensitive to local insolation forcing, instead fluctuating in size on the longer eccentricity time scale (hundreds of thousands of years), in conjunction with other components of the global climate system...."
Island on Fire: The Extraordinary Story of a Forgotten Volcano That Changed the World Feb 1, 2016 by Alexandra Witze @alexwitze Jeff Kanipe
“Deftly interweaving information compiled by naturalists and astronomers of the day (and even Benjamin Franklin, who was in Paris during the eruption) with interviews with modern-day scientists and historians, the authors provide a captivating overview of an eruption.” (Science News)
“Witze and Kanipe have written a compelling and engrossing story of Laki and its worldwide impact. As the best book authors do, they have also ferreted out facts and examples that make their specific story one with implications for modern readers. It is a book that will surely make you want to go to Iceland, or at least pay careful heed to the next time one if its many volcanoes erupt.” (The Seattle Times)
“A revealing new volume. Chapters on geology and the short- and long-term effects of volcanic eruptions add depth to Witze and Kanipe’s discussion, rounding out a work that serves as a valuable reminder of just how much we remain at Mother Nature’s mercy.” (Publishers Weekly)
“A terrific, disturbing book. In their fast-paced, enjoyable text the authors show how vulnerable we remain to the most unpredictable of natural disasters.” (Gillian Darley, author of VESUVIUS)
“A story for the ages. But beneath the barrage of devastation lies an even more profound story: why do we forget these dangers?” (Dr. Lindy Elkins-Tanton, Carnegie Institution for Science)
“A brilliant book. While Iceland’s volcanology became front-page news in 2010 when Eyjafjallajökull grounded flights across Europe for almost a week, Kanipe and Witze situate that recent eruption in the country’s tragic volcanic history and volatile geology.” (Casey N. Cep - Pacific Standard)
“For those with an interest in history and/or geology.” (The Birdbooker Report/Nature.com)
The Unknowns of the Solar Cycle and the Magnetic Field. Bob Zimmerman, BehindtheBlack.com
First sunspot for the next solar cycle spotted
January 3, 2017 at 11:42 am Robert Zimmerman
Solar scientists have spotted the first sunspot on the Sun with a reversed polarity, meaning that it really belongs to the next sunspot cycle.
This is not unusual. The sunspots from different cycles routinely overlap by several years, with the sunspots from the old cycle moving close to the equator with time and the new cycle sunspots appearing at high latitudes. What this does suggest is that there will be sunspots after the upcoming solar minimum, rather than the beginning of a new Grand Minimum with no sunspots for decades.
The recent changes in Earth’s magnetic field
December 23, 2016 at 11:44 am Robert Zimmerman
New data from Europe’s Swarm constellation of satellites detail the recent bigger-than-expected changes that have been occurring in the Earth’s magnetic field.
Data from Swarm, combined with observations from the CHAMP and Ørsted satellites, show clearly that the field has weakened by about 3.5% at high latitudes over North America, while it has strengthened about 2% over Asia. The region where the field is at its weakest – the South Atlantic Anomaly – has moved steadily westward and weakened further by about 2%. These changes have occured over the relatively brief period between 1999 and mid-2016.
It was already known that the field has weakened globally by about 10% since the 19th century. These changes appear to be part of that generally weakening. Some scientists have proposed that this is the beginning of an overall flip of the magnetic field’s polarity, something that happens on average about every 300,000 years and last occurred 780,000 years ago. At the moment, however, we have no idea if this theory is correct.
NASA- Solar Cycle
NASA- Magnetic Field
Bacteria Preserve a Record of Earth's Magnetic Fields
Upper part of Earth’s magnetic field reveals details of a dramatic past
Long before Mercury, Venus, Earth, and Mars formed, it seems that the inner solar system may have harbored a number of super-Earths—planets larger than Earth but smaller than Neptune. If so, those planets are long gone—broken up and fallen into the sun billions of years ago largely due to a great inward-and-then-outward journey that Jupiter made early in the solar system's history.
This possible scenario has been suggested by Konstantin Batygin, a Caltech planetary scientist, and Gregory Laughlin of UC Santa Cruz in a paper that appears the week of March 23 in the online edition of the Proceedings of the National Academy of Sciences (PNAS). The results of their calculations and simulations suggest the possibility of a new picture of the early solar system that would help to answer a number of outstanding questions about the current makeup of the solar system and of Earth itself.For example, the new work addresses why the terrestrial planets in our solar system have such relatively low masses compared to the planets orbiting other sun-like stars.
"Our work suggests that Jupiter's inward-outward migration could have destroyed a first generation of planets and set the stage for the formation of the mass-depleted terrestrial planets that our solar system has today," says Batygin, an assistant professor of planetary science. "All of this fits beautifully with other recent developments in understanding how the solar system evolved, while filling in some gaps."
Thanks to recent surveys of exoplanets—planets in solar systems other than our own—we know that about half of sun-like stars in our galactic neighborhood have orbiting planets. Yet those systems look nothing like our own. In our solar system, very little lies within Mercury's orbit; there is only a little debris—probably near-Earth asteroids that moved further inward—but certainly no planets. That is in sharp contrast with what astronomers see in most planetary systems. These systems typically have one or more planets that are substantially more massive than Earth orbiting closer to their suns than Mercury does, but very few objects at distances beyond...."
Liquid Water May be Commonplace in Our Solar System. Ceres, Pluto, Mars, Venus. David Grinspoon, @drfunkyspoon @planetarysci
“…The global map was created using an instrument on NASA's Dawn probe, which is currently orbiting the dwarf planet, called the Gamma Ray and Neutron Detector (GRaND).
This instrument detects two kinds of particles:
1) neutrons, one of the particles that make up atoms, and
2) gamma rays, very high-energy light.
When cosmic rays (very high-energy particles from space) crash into the surface of the dwarf planet, the collision can create a spray of debris particles, including neutrons and gamma rays. But the debris isn't random; the characteristics of some of those gamma rays and neutrons can provide information about the chemical composition of the surface of Ceres and to certain depths below the surface. So scientists looking at data from GRaND can learn about the abundance of elements, including potassium, iron and hydrogen on the surface of Ceres, and to a depth of about 3 feet (1 meter).
The instrument cannot directly detect water molecules, but that can be inferred from the data, according to the authors. One way this is done is with computer models, which can recreate the evolution of Ceres, producing various possible outcomes that show how those elements (and water) would be distributed today.
Comparing the models with the new map shows that water ice on Ceres is concentrated near the poles: At high latitudes (past about 40 degrees in both hemispheres), water ice on the surface of Ceres and in the layers just under the surface may compose up to 27 percent of Ceres' mass, according to the new research. Near the equator, the water ice concentration is much lower….”
The impacts of climate change on the oceans are usually depicted using graphs. Lines represent projections of long-term globally averaged quantities such as relentless rises in mean sea surface temperature or acidifica¬tion. But the real ocean is noisy. Its conditions simultaneously undergo fast and slow varia¬tions as well as local, regional and global ones.
It is important to quantify the long-term average state of the ocean. Eventually, the influence of anthropogenic climate change will be larger than that of ongoing natural variability. This transition is known as the emergence. But we are not there yet. The present oceanic signature of anthropogenic climate change is still comparable to, and thus difficult to disentangle from, natural and regional climate variability such as the El Niño Southern Oscillation, cycles in winds and sea surface temperatures over the tropi¬cal east Pacific Ocean.
Emergence will happen at different times in different places. For example, the tropics are already recording extreme temperatures, whereas the emergence is several decades away at mid-latitudes.
Natural climate variability can offset or amplify climate change trends temporarily (see ‘Reading the waves’). For example, an apparent5 slowing or ‘hiatus’ in global average temperature rise between 1998 and 2012 led some critics to downplay anthropogenic climate change. Natural variability also reflects more extreme conditions, such as latest strong El Niño warming event.
As anthropogenic climate change increases, periods of extreme conditions6 are expected to become more frequent, severe and lengthy. These will have adverse effects on marine ecosystems. For example, in 2011 the west coast of Australia encoun¬tered sea surface temperatures that were 2–4 °C warmer than average for 10 weeks. Its kelp forest, usually 800 kilometres long, shrank by 43%.
These fluctuations are confusing for marine-resource managers, policymakers and the public. They make decisions about how best to adapt to climate change difficult, and short term forecasts unreliable. …. “
“Making climate science more relevant. Better indicators for risk management are needed after Paris"
For nearly three decades, the central goal in international climate policy had been to set the political agenda—to engage all countries on the need for action. So long as that was the goal, it was sufficient for policy-makers to focus on simple indicators of climate change, such as global average surface temperature. With the 2015 Paris Agreement, governments launched a process that can move beyond setting agendas to coordinating national policies to manage the climate. Next month in Marrakesh, diplomats will convene to flesh out the Agreement. They need to focus on the infrastructure of data and analysis that will be needed as the Agreement becomes operational. The scientific community can help by identifying better lagging indicators to describe what has changed as policy efforts progress, and leading indicators to focus policy on the right risks as the planet warms….
“…Full-blown efforts to manage climate risks will be extremely expensive. Even in the least-developed countries, the cost will likely far exceed new funds promised under the Paris Agreement. Leverage will be essential so that societies of all types build and embed effective risk management. Although local circumstances vary enormously and each society must work out its own details, a common set of indicators, well-established models, and case studies can help.
The good news is that governments, nongovernmental organizations and businesses are poised to do this if the scientific community can organize climate risk information in ways that align better with policy needs. Much of the needed data and many methods already exist. What is missing are demonstrations of how these data and methods can be used and improved for understanding systemic risks. In practice, it will be hard to work out the best examples within large intergovernmental processes in which formal decision-making requires consensus. Formal agreements on the best approaches to risk indicators are unlikely. Instead, volunteers are needed to show the way. The United States and the European Union are developing climate services that will provide more concrete assessments of risk and response.
Such national efforts, along with local ones, should be designed with an eye to what they teach the rest of the world about what works. Similarly, commercial attention to climate risk management is rising quickly as data and analysis tools become available. Already, many firms are reporting their exposure to regulatory risks, as demanded by many shareholders and a growing number of stock exchanges. Science should help decision-makers understand their true exposure to risk and the full range of management options. The role of international policy processes should be to ensure that such experimentation with methods and approaches happens more globally….”
How each culture views the Universe is guided by its beliefs in, for example, math¬ematical beauty or the structure of reality. If these ideas are deeply rooted, people tend to interpret all data as supportive of them — adding parameters or performing math¬ematical gymnastics to force the fit. Recall how the belief that the Sun moves around Earth led to the mathematically beautiful (and incorrect) theory of epicycles advo¬cated by the ancient Greek philosopher Ptolemy.
Similarly, modern cosmology is augmented by unsubstantiated, mathematically sophis¬ticated ideas — of the multiverse, anthropic reasoning and string theory. The multiverse idea postulates the existence of numerous other regions of space-time, to which we have no access and in which the cosmologi¬cal parameters have different values.
The anthropic argument is then often applied. It holds that our own region has the parameters it does (including those of dark energy and dark matter) because other, more likely values would not have allowed life to develop near a star like the Sun in a galaxy such as the Milky Way1–3. An overlooked problem with this argument is that, accord¬ing to one analysis4, life is 1,000 times more likely to exist 10 trillion years from now around stars that weigh one-tenth the mass of the Sun. This means that terrestrial life might be premature and not the most likely form of life, even in our own Universe4.
A vibrant scientific culture encourages many interpretations of evidence, argues Avi Loeb.
“Where did the moon come from?” has been a persistent question over the eons. Among the rocky planets of the inner solar system, Earth is an anomaly. Mercury and Venus have no moons at all, and Mars has only a couple of potato-shape tiny moons (both less than 15 miles across) that may be captured asteroids.
Earth’s moon, by comparison, is a giant, more than 2,000 miles in diameter.
In recent years, the preferred explanation for the origin of the moon has been “the big whack”: very soon after the formation of Earth and the rest of the solar system, the Mars-size interloper that astronomers have named Theia bumped into Earth. The resulting slosh of debris coalesced into a slightly larger Earth and the moon in orbit around Earth...."
The new rock core drilled at the crater impact site that is thought to have help cause the extinction of the dinosaurs 65 million years ago has helped reveal the crater’s formation and shape, including the existence of an inner ring of mountains which scientists call a peak-ring.
After a decade of planning, the project penetrated 1,335 metres into the sea floor off the coast of Progreso, Mexico, in April and May. Drillers hit the first peak-ring rocks at a depth of 618 metres, and a pinkish granite at 748 metres. Geologists know that the granite must have come from relatively deep in the crust — perhaps 8–10 kilometres down — because it contains big crystals. The size of these crystals suggests that they formed by the slow cooling of deep, molten rock; in contrast, rapid cooling at shallow depth tends to form small crystals. Finding the granite relatively high in the drill core means that something must have lifted it up and then thrown down it on top of other rocks.
That rules out one idea of how craters form, in which the pulverized rock stays mostly in place like hot soup in a bowl. Instead, the core confirms the ‘dynamic collapse’ model of cosmic impacts, in which the asteroid punches a deep hole in the crust, causing the rock to flow like a liquid and spurt skyward. That rock then falls back to Earth, splattering around in a peak ring.
To put it another way, the impact moved the earth like a pebble dropped into a pond of water, causing at least two big circular ripples that flowed just like water but then quickly froze in place to form the two concentric peak-ring mountain ranges….”