The early Earth presents us with a conundrum. 3.75 billion years ago, the Sun is thought to have been 25 percent fainter than it is today. Yet liquid water existed on Earth’s surface instead of the ice we would expect. How? The answer may be carbon dioxide in the atmosphere, a conclusion drawn from work on ancient rocks in northern Quebec. Says Stephen Mojzsis (University of Colorado at Boulder), “We now have direct evidence that Earth’s atmosphere was loaded with CO2 early in its history, which probably kept the planet from freezing and going the way of Mars.”
The rocks studied by Mojzsis and team show the presence of iron carbonates that are thought to have precipitated from oceans of that distant era. And they could only have formed in an atmosphere that contained CO2 levels far higher than we see today. Thus we witness carbon dioxide’s role as a climatic thermostat, raising Earth’s temperatures by holding in the weaker heat provided by the Sun.
The area of Hudson’s Bay under investigation is one of grassland, marshes and lakes. But Mojzsis believes it once offered a different prospect, with dense atmospheric CO2 giving the sky a reddish tinge and ocean water rich in iron lapping onto the beaches. The rocks under investigation are thought to be among the oldest ever found on Earth, roughly the same 3.75 billion years of age as rocks found in western Greenland. Other ancient outcroppings are thought to be nearby, holding out the promise of future insights into Earth’s early climate.
And if that seems a long way from interstellar space, be aware that examining how the conditions for life appeared on Earth is a major thrust in the study of astrobiology. It will help us identify planets where life is likely to develop, and also help us understand the remarkable ways life finds to emerge, adapt and survive under conditions that might otherwise seem hostile. It’s no surprise, then, that NASA’s Astrobiology Institute and Exobiology Program continue to fund this work.
The paper is Dauphas et al., “Identification of chemical sedimentary protoliths using iron isotopes in the > 3750 Ma Nuvvuagittuq supracrustal belt, Canada,” Earth and Planetary Science Letters 254, Issues 3-4 (28 February 2007), pp. 358-376, with abstract online.
Hi Paul
The Archean Earth was a strange place – an atmosphere of hydrogen, carbon dioxide, nitrogen and some methane. A sky of smoggy orange, and probably an average temperature over 50 degrees C (+120 F), plus oceans full of minerals that today form huge commercial deposits in the ground. Just how Life got started in that cauldron is something of a puzzle.
An important caveat is that we have no direct measurement of what the Sun was doing back then. Modelling that assumes constant mass also produces the “faint young Sun” paradox and that’s been assumed for a few decades – but what if the Sun was more massive and lost mass via an enhanced solar wind? There’s evidence of much higher stellar winds in young stars elsewhere, so why not our Sun? If so the Paradox might go away leaving us with the question of just how long the “heavy Sun” lasted.
Yet another reason for studying the stellar wind! Watching how it behaves around other stars may give us new clues about our past.
That would suggest acidic oceans – some of the carbon dioxide would dissolve in seawater, forming carbonic acid (this is incidentally why I believe plans to mitigate global warming by starshades is a stupid idea, since a starshade would not do anything about ocean acidification which is potentially far more dangerous to the biosphere).
Hi andy
Definitely a lot of carbonate in the oceans back then as huge ‘reefs’ of the stuff have been found throughout the geological record of the Archean.
I think you’re right about acidification being a major – and underappreciated – issue from greenhouse gas emissions.
In addition to a CO2 rich atmosphere, there would also have been greater geologic sources of heat on the early Earth. The Earth would have had greater remaining latent heat of formation earlier in its history. Additionally, the amount of radioactive isotopes in the early Earth’s crustal rocks would have been much higher than today (11.5x Potassium-40, 2x Uranium-238, 86x Uranium-235). These abundances (especially K-40) would also have worked to maintain high levels of volcanic activity in the early Earth’s history, which would have provided a constant source of CO2.
Hi Robin
Good points. All the extra rads would’ve made the planet fairly nasty – though the 30% CO2, no oxygen and 90 C temperature already did that. The recent work on hydrogen puts its level at 40%, and with the CO2 at 30%, that means the nitrogen and water vapour are vying for the last 30%… just how heavy was the early atmosphere???
Nitrogen is said to have outgassed pretty rapidly hitting 85% of current levels within a few tens of millions of years. If average global humidity was ~ 50%, and the nitrogen was at ~ 0.7 bar, then about 1.0 bar is that 30% of the atmosphere, so the total is over 3 bar. Hot, nasty and heavy too! Of course that’s minor compared to the 280 bars of steam and about 50 bars of carbon dioxide that the really early atmosphere is believed to have been, while the crust was still red-hot.
Earth has been through some changes over the aeons. I’ve got to wonder what it will be like in a billion years. The ocean is slowly being sunk into the mantle and tectonic processes are slowly down. Will Earth end up dry desert before it has a chance to become a “wet greenhouse” in 1.5 billion years? The Sun is slowly getting brighter – if we leave it to itself.
There’s enough hydrogen for solar fusion to last over 60 billion years, but the Sun’s core doesn’t convect so once it’s choking on helium it can only collapse and eventually start hydrogen-shell burning and the red-giant stage that causes. If our descendents can make it convect then its life might be dramatically extended.
Even if we convert it into helium ash that helium can fuse and another 12 billion years squeezed out of the Sun as a fusion reactor. Of course carbon can fuse too, but the resulting energy is a pitiful 6% of hydrogen fusion, good for a mere 4 billion years. But to fuse carbon takes a more massive star and is even harder to control than helium fusion (which is proportional to the 40th power of the temperature already!)
But the ultimate power source is the conversion of mass to energy and the Sun’s good for 14 TRILLION years of that – though when its mass is below 50% current levels the planets will be detached from their current orbits. A minor detail – the planets might’ve been decomposed into useful mass by then, made into a Matrioshka Brain-style Dyson Cloud.
EARNEST C. WATSON LECTURE SERIES: “SNOWBALL EARTH” (TOP STORIES)
Joe Kirschvink, Caltech’s Van Wingen Professor of Geobiology, will
discuss Earth’s global climate in an Earnest C. Watson Lecture.
Kirschvink’s Snowball Earth hypothesis accounts for a host of new
observations about Precambrian glacial intervals and has led to new
insights about the rise of atmospheric oxygen and major events in
the evolution of life. This event is free, and no tickets or
reservations are required. At 8 to 10 p.m. on Wednesday, February
14, in Beckman Auditorium.
Details: http://events.caltech.edu/events/event-3904.html
What’s humbling is what little we KNOW about past climates, arcahen and recent. I love reading this research but don’t take it seriously given the early weak sun conundrum and the tendency to project one’s beliefs into computer models. What’s exciting is how much we have to learn and the paradigms that will be overturned.
Hi philw
Good points. Every new bit of fossilised soil has told us new things and not always compatible with the previous patch of dirt’s story either. Yet the evidence for a ‘hot’ greenhouse Earth is getting more robust, not less so if there was nothing to it. Would be nice to have a geochemical proxy on the hydrogen levels.
Cold Climate Produced By Algae Contributed To Onset Of Multicellular Life
Los Angeles CA (SPX) Feb 15, 2007
The rise of multicellular animals about 540 million years ago was a turning point in the history of life. A group of Finnish scientists suggests a new climate-biosphere interaction mechanism for the underlying processes in a new study, which will be published on February 14, 2007 in PLoS ONE, the international, peer-reviewed, open-access, online publication from the Public Library of Science (PLoS).
http://www.terradaily.com/reports/Cold_Climate_Produced_By_Algae_Contributed_To_Onset_Of_Multicellular_Life_999.html
Astrophysics, abstract
astro-ph/0702529
From: Jorge Sanz-Forcada [view email]
Date: Tue, 20 Feb 2007 15:03:11 GMT (337kb)
Habitat of early life: Solar X-ray and UV radiation at Earth’s surface 4-3.5 billion years ago
Authors: I. Cnossen, J. Sanz-Forcada, F. Favata, O. Witasse, T. Zegers, N. F. Arnold
Comments: 19 pages, published by JGR-Planets
Journal-ref: Journal of Geophysical Research, 112, E02008 (2007)
DOI: 10.1029/2006JE002784
Solar X-ray and UV radiation (0.1-320 nm) received at Earth’s surface is an important aspect of the circumstances under which life formed on Earth. The quantity that is received depends on two main variables: the emission of radiation by the young Sun and its extinction through absorption and scattering by the Earth’s early atmosphere. The spectrum emitted by the Sun when life formed, between 4 and 3.5 Ga, was modeled here, including the effects of flares and activity cycles, using a solar-like star that has the same age now as the Sun had 4-3.5 Ga. Atmospheric extinction was calculated using the Beer-Lambert law, assuming several density profiles for the atmosphere of the Archean Earth.
We found that almost all radiation with a wavelength shorter than 200 nm is attenuated effectively, even by very tenuous atmospheres. Longer-wavelength radiation is progressively less well attenuated, and its extinction is more sensitive to atmospheric composition. Minor atmospheric components, such as methane, ozone, water vapor, etc., have only negligible effects, but changes in CO2 concentration can cause large differences in surface flux. Differences due to variability in solar emission are small compared to this.
In all cases surface radiation levels on the Archean Earth were several orders of magnitude higher in the 200-300 nm wavelength range than current levels in this range. That means that any form of life that might have been present at Earth’s surface 4-3.5 Ga must have been exposed to much higher quantities of damaging radiation than at present.
http://arxiv.org/abs/astro-ph/0702529
Science/Astronomy:
* Out-of-This-World Hypothesis: Cosmic Forces Control Life on Earth
http://bcast1.imaginova.com/t?r=2&ctl=F959:4A48D
The rise and fall of species on Earth might be driven in part by the undulating
motions of our Solar System through the Milky Way’s galactic plane, scientists
say.
Building A Habitable Earth
Lyon, France (SPX) Jun 04, 2007 – Astrobiologists have a strong interest in understanding the conditions that prevailed on the early Earth, but the record for the first 650 million years of Earth history is gone. The earlier stages that made our planet fit for life are not recorded in the rocks we have today. The Earth was not a habitable planet when it first formed: it was a seething cauldron of molten material, with impa … more:
http://www.terradaily.com/reports/Building_A_Habitable_Earth_999.html
Geochemistry of U and Th and its Influence on the Origin and Evolution of the Crust of Earth and the Biological Evolution
Authors: Xuezhao Bao, Ali Zhang
(Submitted on 7 Jun 2007 (v1), last revised 9 Jun 2007 (this version, v2))
Abstract: We have investigated the migration behaviors of uranium (U) and thorium (Th) in the Earth and other terrestrial planets. Theoretical models of U and Th migration have been proposed. These models suggest that the unique features of the Earth are closely connected with its unique U and Th migration models and distribution patterns. In the Earth, U and Th can combine with oxidative volatile components and water, migrate up to the asthenosphere position to form an enrichment zone (EZ) of U and Th first, and then migrate up further to the crusts through magmatism and metamorphism. We emphasize that the formation of an EZ of U, Th and other heat-producing elements is a prerequisite for the formation of a plate tectonic system. The heat-producing elements, currently mainly U and Th, in the EZ are also the energy sources that drive the formation and evolution of the crust of Earth and create special granitic continental crusts. In other terrestrial planets, including Mercury, Venus, and Mars, an EZ can not be formed because of a lack of oxidative volatile components and water. For this reason, a plate tectonic system can not been developed in these planets. We also emphasize the influence of U and Th in EZ on the development and evolution of life on Earth. We propose that since the Earth and planets were born in a united solar system, there should have existed some common mechanisms to create the similarities and differences between them. We have tried to develop an integrated view to explain some problems in the tectonics of Earth and evolution, bio-evolution, and planetary dynamics through U and Th geochemistry. We believe that a comprehensive exploration on energy sources and their evolution is a good way to build up bridges between different disciplines of science in order to understand the Earth and planets.
Comments: 17 pages, 3 figures, 2 tables
Subjects: Geophysics (physics.geo-ph); Astrophysics (astro-ph); Populations and Evolution (q-bio.PE)
Journal reference: Acta Petrologicav et Mineralogica, 17(2): 160-172 (1998)
Cite as: arXiv:0706.1089v2 [physics.geo-ph]
Submission history
From: Xuezhao Bao [view email]
[v1] Thu, 7 Jun 2007 21:23:22 GMT (381kb)
[v2] Sat, 9 Jun 2007 12:30:29 GMT (381kb)
http://arxiv.org/abs/0706.1089
Theory Describing the Synthesis of Early Life-Forming
Chemicals is Presented in Astrobiology
http://www.astrobiology.com/news/viewpr.html?pid=23063
“Understanding how life on Earth began requires a
clear explanation of the chemical reactions necessary
to synthesize the basic building blocks of life. An
exciting new report that presents potential mechanisms
for nucleobase synthesis in interstellar space and
under the conditions of early Earth is featured in
the June issue of Astrobiology.”
UQ Researchers Discover Some Of The Oldest Forms Of Life
The core drilling samples from Western Australia’s Pilbara region were collected by PhD student Lawrie Duck who said it was an amazing experience to “hold in your hands rocks that contain remains of some of the earliest forms of life on Earth.”
by Staff Writers
Brisbane, Australia (SPX) Aug 08, 2007
University of Queensland researchers have identified microbial remains in some of the oldest preserved organic matter on Earth, confirmed to be 3.5 billion years-old. The UQ team, led by School of Physical Sciences scientists Dr Miryam Glikson and Associate Professor Sue Golding as well as Associate Professor Lindsay Sly from the School of Molecular and Microbial Sciences, are the first to conclusively confirm the nature and source of the organic material.
Aspects of the research have been published in the prestigious scientific journal Precambrian Research. “What we have found is the first visual confirmation of primitive microbial communities in what is considered to be the best preserved ancient organic matter on our planet,” Dr Glikson, the instigator of the research, said.
Dr Golding, Director UQ’s Stable Isotope Laboratory in the Division of Earth Sciences, said previous studies used indirect analytical methods that were only able to suggest microbial involvement, not confirm it.
“We used difficult and time-consuming electron microscope techniques to conclusively confirm the microbial remains,” Dr Golding said.
“The integration of observational and micro-analytical techniques is unique to our approach.”
Full article here:
http://www.terradaily.com/reports/UQ_Researchers_Discover_Some_Of_The_Oldest_Forms_Of_Life_999.html
Origin of the Ocean on the Earth: Early Evolution of Water D/H in a Hydrogen-rich Atmosphere
Authors: Hidenori Genda, Masahiro Ikoma
(Submitted on 13 Sep 2007)
Abstract: The origin of the Earth’s ocean has been discussed on the basis of deuterium/hydrogen ratios (D/H) of several sources of water in the solar system. The average D/H of carbonaceous chondrites (CCs) is known to be close to the current D/H of the Earth’s ocean, while those of comets and the solar nebula are larger by about a factor of two and smaller by about a factor of seven, respectively, than that of the Earth’s ocean. Thus, the main source of the Earth’s ocean has been thought to be CCs or adequate mixing of comets and the solar nebula. However, those conclusions are correct only if D/H of water on the Earth has remained unchanged for the past 4.5 Gyr. In this paper, we investigate evolution of D/H in the ocean in the case that the early Earth had a hydrogen-rich atmosphere, the existence of which is predicted by recent theories of planet formation no matter whether the nebula remains or not. Then we show that D/H in the ocean increases by a factor of 2-9, which is caused by the mass fractionation during atmospheric hydrogen loss, followed by deuterium exchange between hydrogen gas and water vapor during ocean formation. This result suggests that the apparent similarity in D/H of water between CC’s and the current Earth’s ocean does not necessarily support the CC’s origin of water and that the apparent discrepancy in D/H is not a good reason for excluding the nebular origin of water.
Comments: Accepted to Icarus
Subjects: Astrophysics (astro-ph); Atmospheric and Oceanic Physics (physics.ao-ph)
Cite as: arXiv:0709.2025v1 [astro-ph]
Submission history
From: Hidenori Genda [view email]
[v1] Thu, 13 Sep 2007 09:09:23 GMT (441kb)
http://arxiv.org/abs/0709.2025
Five or six step scenario for evolution?
Authors: Brandon Carter
(Submitted on 13 Nov 2007)
Abstract: The prediction that (due to the limited amount of hydrogen available as fuel in the Sun) the future duration of our favourable terrestrial environment will be short (compared with the present age of the Earth) has been interpreted as evidence for a hard step scenario. This means that some of the essential steps (such as the development of eukaryotes) in the evolution process leading to the ultimate emergence of intelligent life would have been hard, in the sense of being against the odds in the available time, so that they are unlikely to have been achieved in most of the earth-like planets that may one day be discovered in nearby extra-solar systems. It was originally estimated that only one or two of the essential evolutionary steps had to have been hard in this sense, but it has become apparent that this figure may need upward revision, because recent studies of climatic instability suggest that the possible future duration of our biologically favourable environment may be shorter than had been supposed, only about one Giga year rather than five. On the basis of the statistical requirement of roughly equal spacing between hard steps, it is argued that the best fit with the fossil record is now obtainable by postulating the number of hard steps to be five, if our evolution was exclusively terrestrial, or six if, as now seems very plausible, the first step occurred on Mars.
Comments: 11 pages Latex
Subjects: Astrophysics (astro-ph)
Cite as: arXiv:0711.1985v1 [astro-ph]
Submission history
From: Brandon Carter [view email]
[v1] Tue, 13 Nov 2007 14:14:15 GMT (83kb)
http://arxiv.org/abs/0711.1985
Liquid Crystal Life
http://www.astrobio.net/news/article2539.html
Scientists studying ultrashort DNA molecules have provided
a new scenario for how life may have originated on Earth.
The team found that short segments of DNA are able to
assemble into distinct liquid crystal phases. The research
may help us understand how life could have originated from
segments of DNA-like molecules.
New hypothesis for origin of life proposed
PhysOrg.com Dec. 4, 2007
*************************
Life may have begun in the
protected spaces inside of layers of
the mineral mica, in ancient oceans,
according to a new hypothesis by
Helen Hansma, a research scientist
with the University of California,
Santa Barbara.
Photo of mica from an
abandoned mica mine, with brown
bands of organic material (Helen
Greenwood Hansma, UC Santa…
http://www.kurzweilai.net/email/newsRedirect.html?newsID=7574&m=25748
http://www.terradaily.com/reports/Thaw_point_Snowball_Earth_was_more_a_slushball_999.html
Thaw point: ‘Snowball Earth’ was more a slushball
by Staff Writers
Paris (AFP) Dec 5, 2007
An extraordinary episode of global cooling hundreds of millions of years ago that some experts say caused Earth to completely freeze over has been miscalculated, a new study says.
Instead of “Snowball Earth,” the planet really became “Slushball Earth,” its authors suggest.
The great chill — the longest and deepest ice age in Earth’s known history — happened during the late Neoproterozoic era, 850 to 542 million years ago.
The evidence for the Snowball thesis comes from deep sediments in the ocean.
Scientists look through these layers to measure levels of the isotope carbon 13 (C13), deposited in plants through photosynthesis, as a telltale of Earth’s climate.
Above and below the Cryogenian layer is an abundance of C13. But the Cryogenian layer itself has negligible levels of this isotope.
Coupled with other signs of intense glaciation, the explanation is that Earth froze over completely — thick ice covered the oceans and glaciers crept down into the tropics, possibly even reaching the equator.
The brilliant white shell reflected back the Sun’s rays, and thus its heat, so well that the Snowball persisted for nearly 200 million years.
Eventually the greenhouse gas carbon dioxide (CO2), welling up from volcanoes, escaped into the air and thankfully set the planet onto a warming trend, and so the icy blanket was melted.
This scenario, first aired in 1989 and still fiercely contested, has now come under assault from a new angle by a trio of physicists at the University of Toronto, Canada.
They have devised a computer simulation of the CO2 during the late Neoproterozoic that factors in the role of oxygen in the ocean.
Progressive cooling would have allowed atmospheric oxygen to spread more deeply into the sea, transforming rich layers of dissolved organic carbon — formerly created by photosynthesis — into CO2, they say.
This CO2, released back into the atmosphere, warmed up the atmosphere through the greenhouse effect sufficiently to induce thawing, causing sea ice and glaciers to shrink, before a cooling cycle resumed.
In other words, the Cryogenian would have been a milder, slushier, shorter affair, with ice-free seas in the tropics where sunlight would have generated photosynthesis, rather than a deep, long, planetary freeze.
The ice age would not have required massive amounts of volcanic CO2 to end, nor would it have been delayed by millions of years.
In a commentary, which like the study appears in Thursday in the British journal Nature, US geologist Alan Kaufman questions Peltier’s assumption that levels of atmospheric oxygen were similar to today’s level — a relatively high 21 percent of the air.
“Biological and geochemical evidence indicates that oxygen levels were low throughout most of the Neoproterozoic, with a significant rise in breathable air around 550 million years ago — about the time animals first appeared on the planet,” says Kaufman.
The Snowball debate has a bearing on another great enigmatic episode in Earth’s history called the “Cambrian Explosion” — the dramatic breakout of biodiversity that happened after the Neoproterozoic.
The microfossil record from this time is so emphatic that no one doubts that the Explosion happened.
Critics of the Snowball theory say that such a prolonged deep glaciation would have destroyed all life, leaving nothing left — or at least very little — to explain this sudden, riotous diversity.
Snowball supporters, though, argue that hardy microscopic biota survived unscathed during the long chill, thriving in shallow sea waters or melt pools on land in the tropics, or in thermal vents on the sea bed.
When the Snowball melted, these organisms grew swiftly in size and complexity, becoming the new masters of the planet, they contend.
Maybe Sulfur Dioxide, Not Carbon Dioxide, Kept Mars Warm
Written by Fraser Cain
Try to walk on Mars today, and the planet will simultaneously
freeze and suffocate you. Not to mention the minimal air
pressure and relentless radiation from space. But billions of
years ago, the Red Planet was much warmer and liquid water
flowed on its surface. Warm temperatures on Earth are
maintained by the carbon cycle, but maybe another
greenhouse gas – sulfur dioxide (SO2) – maintained the
temperatures on Mars.
This is the hypothesis put forward by Harvard and MIT
researchers, published in the December 21st edition of
the journal Science.
Full article here:
http://www.universetoday.com/2007/12/20/maybe-sulfur-dioxide-not-carbon-dioxide-kept-mars-warm/
Did Earthquakes Keep the Early Crust Habitable?
http://www.spaceref.com/news/viewsr.nl.html?pid=26529
“The shallow habitable region of cratonal crust deforms
with a strain rate on the order of 1019 s1. This is rapid
enough that small seismic events are expected on one-
kilometer spatial scales and one-million-year timescales.
Rock faulting has the potential to release batches of biological
substrate, such as dissolved H2, permitting transient blooms.”
Hot springs microbes hold key to dating sedimentary
rocks, researchers say
http://www.spaceref.com/news/viewpr.nl.html?pid=24656
“Scientists studying microbial communities and the growth
of sedimentary rock at Mammoth Hot Springs in Yellowstone
National Park have made a surprising discovery about the
geological record of life and the environment.”
Seafloor Chemistry: Life’s building blocks made inorganically
Hydrocarbons in fluids spewing from hydrothermal vents
on the seafloor in the central Atlantic were produced by
inorganic chemical reactions deep within the ocean crust,
a finding with implications for the possible origins of life.
http://www.sciencenews.org/articles/20080202/fob1.asp
Scientists rebuild ancient proteins to reveal primordial
Earth’s temperature
http://www.spaceref.com/news/viewpr.nl.html?pid=24720
“Using the genetic equivalent of an ancient thermometer,
a team of scientists has determined that Earth endured a
massive cooling period between 500 million and 3.5 billion
years ago.”
Two Oxygenation Events In Ancient Oceans Sparked
Spread Of Complex Life
(February 26, 2008) — The rise of oxygen and the oxidation
of deep oceans between 635 and 551 million years ago may
have had an impact on the increase and spread of the earliest
complex life, including animals.
Today, we take oxygen for granted. But the atmosphere had
almost no oxygen until 2.5 billion years ago, and it was not
until about 600 million years ago when the atmospheric oxygen
level rose to a fraction of modern levels.
For a long time, geologists and evolutionary biologists have
speculated that the rise of the breathing gas and subsequent
oxygenation of the deep oceans are intimately tied to the
evolution of modern biological systems. … > full story
http://www.sciencedaily.com/releases/2008/02/080225213645.htm
Key component of Earth’s crust formed from moving, molten rock, Cornell researchers discover
http://www.news.cornell.edu/stories/March08/eas.crust.aj.html
March 5, 2008
By Anne Ju
amj8@cornell.edu
Earth scientists are in the business of backing into history — extrapolating what happened millions of years ago based on what they can observe now. Using this method, a team of Cornell researchers has created a mathematical computer model of the formation of granulite, a fine-grained metamorphic rock, in the Earth’s crust.
By studying what were once pockets of hot, melted rock 13 kilometers (about 8 miles) deep in the Earth’s crust 55 million years ago and calculating the period of cooling, the scientists were able to explain how granulite is formed as the molten rock migrates upward through the crust.
The research is published in the March issue of the journal Nature by Gabriela V. Depine, a fourth-year graduate student in earth and atmospheric sciences (EAS); Christopher L. Andronicos, an EAS associate professor; and Jason Phipps-Morgan, professor of EAS. The research is funded by Cornell and by the National Science Foundation’s Continental Dynamics program.
Granny Says Life Evolved Between the Mica Sheets
Scientists hypothesizes that life evolved between the
thin, flaky sheets of mica.
http://www.livescience.com/strangenews/080314-bts-hansma.html
Hi ljk and other Folks;
Great discussion thread by the way!
This article about the possibility of mica as the location in which life evolved is intreaguing to me. Chemicals may be trapped in mica for as long as the mica exists, essentially for 100s of millions of years if not billions of years in certain cases, plenty of time perhaps for random thermodynamic combinations of atoms and molecules to produce biological molecules, perhaps even crude life forms, or the very least complex organic molecules.
It is possible that cosmic rays or other ionizing radiation may occasionally pass through an organic materials containing pocket within a piece of mica in order to greatly perturb local molecular structures in an instant. Repeated strikes by such ionizing radiation, whether it be photons, neutrons, or charge particles might produce a time averaged great enough variety in the thermodynamic degrees of freedom within the chemical containing pores within the mica to have caused life to originate on Earth.
One has merely to consider the huge number of differential mica volumes that have contained chemical filled pores over the early history of the Earth and it becomes very plausible that life may have originated this way. Some of the organic compounds might have arrived on Earth by asteriod or by other means; but upon arrival, they may have become trapped, in very numerous instances, within mica deposits.
I can see how tiny mica vessels might allow for the initial formation of complex organic compounds, and while providing a gentle and shielded environment for these complex compounds to react over a period of thousands, millions, if not billions of years, perhaps the subsequent formation of primitive life forms.
Thanks;
Jim
Warming the early Earth – CO2 reconsidered
Authors: P. von Paris (DLR), H. Rauer (DLR, TUB), L. Grenfell (DLR, TUB), B. Patzer (TUB), P. Hedelt (DLR), B. Stracke (DLR), T. Trautmann (DLR), F. Schreier (DLR)
(Submitted on 25 Apr 2008)
Abstract: Despite a fainter Sun, the surface of the early Earth was mostly ice-free. Proposed solutions to this so-called “faint young Sun problem” have usually involved higher amounts of greenhouse gases than present in the modern-day atmosphere. However, geological evidence seemed to indicate that the atmospheric CO2 concentrations during the Archaean and Proterozoic were far too low to keep the surface from freezing. With a radiative-convective model including new, updated thermal absorption coefficients, we found that the amount of CO2 necessary to obtain 273 K at the surface is reduced up to an order of magnitude compared to previous studies.
For the late Archaean and early Proterozoic period of the Earth, we calculate that CO2 partial pressures of only about 2.9 mb are required to keep its surface from freezing which is compatible with the amount inferred from sediment studies. This conclusion was not significantly changed when we varied model parameters such as relative humidity or surface albedo, obtaining CO2 partial pressures for the late Archaean between 1.5 and 5.5 mb. Thus, the contradiction between sediment data and model results disappears.
Comments: 55 pages, 4 tables, 11 figures, accepted in Planetary and Space Science
Subjects: Astrophysics (astro-ph)
DOI: 10.1016/j.pss.2008.04.008
Cite as: arXiv:0804.4134v1 [astro-ph]
Submission history
From: Philip von Paris [view email]
[v1] Fri, 25 Apr 2008 15:51:19 GMT (77kb)
http://arxiv.org/abs/0804.4134
Early life could have relied on ‘arsenic DNA’
New Scientist April 26, 2008
The first lifeforms might have
evolved to make use of arsenic,
Felisa Wolfe-Simon of Harvard
University and Paul Davies of
Arizona State University suggest.
Arsenic readily forms arsenate ions
and behaves like phosphorus, which
binds to four oxygen atoms to form a
negatively charged phosphate ion
that is used to build the backbone
of DNA’s…
http://www.kurzweilai.net/email/newsRedirect.html?newsID=8545&m=25748
Rest In Peace Nanobacteria, You Were Not Alive After All
Science News April 23, 2008
*************************
Once touted as the world’s smallest
living organisms, and even an
entirely new form of life,
“nanobacteria” are actually nothing
more than sub-microscopic balls of
minerals and proteins, independent
teams of scientists in Taiwan and
France report. However, nanobacteria
have been linked to kidney stone and
gallstone formation, polycystic
kidney…
http://www.kurzweilai.net/email/newsRedirect.html?newsID=8546&m=25748
OVERHEATED EARTH MAY BE LOCKED IN PLACE
Dramatic changes to the temperature of Earth’s atmosphere
could cause the planet’s crust to become locked in place,
research shows.
http://abcmail.net.au/t/159577/687780/3379/0/
Large methane release could cause abrupt climate change as
happened 635 million years ago
PhysOrg.com May 28, 2008
An abrupt release about 635 million
years ago of methane, a powerful
greenhouse gas, from ice sheets that
then extended to Earth’s low
latitudes, caused a dramatic shift
in climate, triggering a series of
events that resulted in global
warming and ended the last
“snowball” ice age, a UC
Riverside-led study…
http://www.kurzweilai.net/email/newsRedirect.html?newsID=8774&m=25748
Palaeobiology: The Cambrian smorgasbord
Source: Nature
http://www.nature.com/news/2008/080604/full/453717a.html
Published online 4 June 2008 | Nature 453, 717-718 (2008) |
doi:10.1038/453717a
Animal behaviour is an endless challenge to mathematical modellers. In the first of two features, Mark Buchanan looks at how a mathematical principle from physics might be able to explain patterns of movement. In this, the second, Arran Frood asks what current models can teach us about ecological networks half a billion years old.
Ecosystems on other planets would be a great help in sorting out the necessary from the contingent, but remain stubbornly undiscovered. Mimicry in the lab can’t capture the necessary subtlety. Food webs from the fossil record might thus be the closest to something completely different that contemporary researchers can ever hope to get their hands on. And the Burgess Shale fauna from British Columbia, Canada, were the obvious choice.
In the years after that original lunch, Dunne and Erwin mined existing databases and compiled, reviewed and revised the two Cambrian food webs. “Our first surprise was that we could put these data together,” says Dunne. With the food webs ready, the team then analysed them according to the ‘niche model’ first promulgated by Richard Williams and Neo Martinez1..
In the niche model, each predator is constrained to eating from one ‘dimension’, and is expected to eat everything in that dimension. So if a dolphin eats tuna and sardines, it is presumed to eat everything between the two on that dimension. In practice, such a dimension maps closely to body size, but that’s not how it is defined; it is a statistical creation that represents many traits, of which body size simply happens to be a significant one in most systems.
Just three of the 17 properties of the Burgess Shale web that they measured fell outside the predictions of the niche model. “Most palaeobiologists would assume that these half-billion-year-old food webs should look really different from modern food webs,” says Dunne. “But it looks like in most ways, at least that we characterize, the organization looks really similar.”2
Ion Microprobe Technology Reveals Earth was Habitable 4.3 Billion Years Ago
A team of scientists led by University of Wisconsin-Madison geologists Takayuki Ushikubo, Valley and Noriko Kita have completed an analysis of ancient minerals called zircons which shows liquid water existed at least 4.3 billion years ago and that heavy weathering by an acrid climate possibly destroyed the surface of the Earth’s earliest continents when the planet was a mere 150 million years old.
Zircons, the oldest known materials on Earth, offer a window in time back as far as 4.4 billion years ago. Because these crystals are exceptionally resistant to chemical changes, they have become the gold standard for determining the age of ancient rocks, says UW-Madison geologist John Valley.
Valley previously used these tiny mineral grains — smaller than a speck of sand — to show that rocky continents and liquid water formed on the Earth much earlier than previously thought, about 4.2 billion years ago.
Ushikubo, the first author on the new study, says that atmospheric weathering could provide an answer to a long-standing question in geology: why no rock samples have ever been found dating back to the first 500 million years after the Earth formed.
Full article here:
http://www.dailygalaxy.com/my_weblog/2008/06/ion-microprobe.html
A Warm Breath of Carbon Dioxide
http://www.spaceref.com/news/viewsr.html?pid=29101
“Early in Earth’s history, our solar system was a much different place.
When the sun was very young, it was faint and provided little heat
for the Earth. However, even in its chilly beginnings, the surface of
the Earth was ice-free. For years, scientists have proposed theories
for this “faint young sun problem”.
Decline of carbon dioxide-gobbling plankton coincided with ancient global cooling
http://www.news.cornell.edu/stories/Jan09/diatom.evolution.hp.html
Jan. 7, 2009 By Hugh Powell
cunews@cornell.edu
The evolutionary history of diatoms — abundant oceanic plankton that remove billions of tons of carbon dioxide from the air each year — needs to be rewritten, according to a new Cornell study. The findings suggest that after a sudden rise in species numbers, diatoms abruptly declined about 33 million years ago — trends that coincided with severe global cooling.
The study is published in the Jan. 8 issue of the journal Nature. The research casts doubt on the long-held theory that diatoms’ success was tied to an influx of nutrients into the oceans from the rise of grasslands about 18 million years ago.
New evidence from a study led by graduate student Dan Rabosky of the Cornell Laboratory of Ornithology takes into account a widespread problem in paleontology: that younger fossils are easier to find than older ones.
“We just tried to address the simple fact that the number of available fossils is colossally greater from recent time periods than from earlier time periods,” Rabosky said. “It’s a pretty standard correction in some fields, but it hasn’t been applied to planktonic paleontology up till now.”
More than 90 percent of known diatom fossils are younger than 18 million years. So an unadjusted survey of diatom fossils suggests that more diatom species were alive in the recent past than 18 million years ago. The dearth of early fossils is understandable. Sampling for diatom fossils requires immense drill ships to bore into seafloor sediment.
To find an ancient fossil, scientists first have to find ancient sediment — and that’s no easy task because plate tectonics constantly shift the ocean floor, fossils and all. Much of the seafloor is simply too young to sample. So Rabosky and co-author Ulf Sorhannus of Edinboro University of Pennsylvania controlled for how many samples had been taken from each million-year period of the Earth’s history, going back 40 million years.
After reanalysis, the long-accepted boom in diatoms over the last 18 million years disappeared. In its place was a slow recent rise, with a much more dramatic increase and decline at the end of the Eocene epoch, about 33 million years ago. With the new timeline, diatoms achieved their peak diversity at least 10 million years before grasslands became commonplace.
“If there was a truly significant change in diatom diversity at all, it happened 30 million years ago,” Rabosky said. “The shallow, gradual increase we see is totally different from the kind of exponential increase you would expect if grasslands were the cause.”
As an example of that kind of increase, Rabosky turned to another fossil record: horse teeth. Before grasslands, horses had small teeth suited for chewing soft leaves. But as grasslands appeared, much hardier teeth appeared adapted to a lifetime of chewing tough, silica-studded grass leaves. Diatoms ought to show a similar evolutionary response to the sudden availability of silica, Rabosky said, but they don’t.
Although the new results don’t explain the current prevalence of diatoms in the ocean, Rabosky said that whatever led to diatoms’ rise at the end of the Eocene, the tiny organisms may have contributed to the global cooling that followed.
“Why diatom diversity peaked for 4 to 5 million years and then dropped is a big mystery,” Rabosky said. “But it corresponds with a period when the global climate swung from hothouse to icehouse. It’s tempting to speculate that these tiny plankton, by taking carbon dioxide out of the air, might have helped trigger the most severe global cooling event in the past 100 million years.” The research was supported in part by the National Science Foundation.
== Hugh Powell is a science writer at Cornell’s Lab of Ornithology.
EARLY OCEANS HAD OXYGEN-LOVING LIFE
Simple, photosynthesising life forms created an excess of oxygen in the oceans 700 million years earlier than previous estimates suggest, an international team of geologists claim.
http://abcmail.net.au/t/422357/687780/8281/0/
Deep-sea Rocks Point to Early Oxygen on Earth
http://www.spaceref.com/news/viewpr.html?pid=27813
“Red jasper cored from layers 3.46 billion years old suggests that not only did the oceans contain abundant oxygen then, but that the atmosphere was as oxygen rich as it is today, according to geologists. This jasper or hematite-rich chert formed in ways similar to the way this rock forms around hydrothermal vents in the deep oceans today.”
April 9, 2009
Without Nickel, Life on Earth Could Finally Breathe
Written by Anne Minard
Caption: Banded iron formations like this from northern Michigan contain evidence of a drop in dissolved nickel in ancient oceans. Credit: Carnegie Institution for Science
Researchers have long puzzled over why oxygen flourished in Earth’s atmosphere starting around 2.4 billion years.
Called the “Great Oxidation Event,” the transition “irreversibly changed surface environments on Earth and ultimately made advanced life possible,” said Dominic Papineau of the Carnegie Institution’s Geophysical Laboratory.
Now, Papineau has co-authored a new study in the journal Nature, which reveals new clues to the mystery in ancient sedimentary rocks.
The research team, led by Kurt Konhauser of the University of Alberta in Edmonton, analyzed the trace element composition of sedimentary rocks known as banded-iron formations, or BIFs, from dozens of different localities around the world, ranging in age from 3,800 to 550 million years.
Banded iron formations are unique, water-laid deposits often found in extremely old rock strata that formed before the atmosphere or oceans contained abundant oxygen. As their name implies, they are made of alternating bands of iron and silicate minerals.
They also contain minor amounts of nickel and other trace elements. And the history of nickel, the researchers think, may reveal a secret to the origin of modern life.
Full article here:
http://www.universetoday.com/2009/04/09/without-nickel-life-on-earth-could-finally-breathe/