6.4 – Geologic and Geochemical Constraints on Earth's Early Atmosphere
- Geology, Environmental Science
Chemical evolution and early Earth's and Mars' environmental conditions 1
Life originated more than 3.5 billion years ago either on Earth or on our neighbour planet Mars from where it reached Earth by lithopanspermia. Life’s origin was preceded by an abiotic chemical…
Detecting the oldest geodynamo and attendant shielding from the solar wind: Implications for habitability
- Geology, Physics
Atmospheric Prebiotic Chemistry and Organic Hazes
- Environmental ScienceCurrent organic chemistry
The results highlighted here show that a variety of products can be formed in mildly reducing or even neutral atmospheres, demonstrating that contributions of atmospheric synthesis to the organic inventory on early Earth should not be discounted.
Organic Haze as a Biosignature in Anoxic Earth-like Atmospheres
- Geology, PhysicsAstrobiology
It is shown that organic haze formation requires methane fluxes consistent with estimated Earth-like biological production rates and detection of haze at an anomalously low CH4/CO2 ratio could suggest the influence of these biogenic sulfur gases and therefore imply biological activity on an exoplanet.
Evidence for elevated and variable atmospheric oxygen in the Precambrian
- Environmental Science, Geography
SHOWING 1-10 OF 289 REFERENCES
How Earth's atmosphere evolved to an oxic state: A status report
- Environmental Science
Palaeoclimates: the first two billion years
- Environmental Science, GeographyPhilosophical Transactions of the Royal Society B: Biological Sciences
A rise in O2 at approximately 2.4 Ga, and a concomitant decrease in CH4, provides a natural explanation for the Palaeoproterozoic glaciations.
Evolution of the atmosphere.
- Geology, Environmental ScienceProceedings of the Geologists' Association. Geologists' Association
Atmospheric carbon dioxide concentrations before 2.2 billion years ago
- Environmental ScienceNature
The results suggest that either the Earth's early climate was much more sensitive to increases in pco2 than has been thought, or that one or more greenhouse gases other than CO2 contributed significantly to the atmosphere's radiative balance during the late Archaean and early Proterozoic eons.
The Paleoproterozoic snowball Earth: a climate disaster triggered by the evolution of oxygenic photosynthesis.
- Geography, GeologyProceedings of the National Academy of Sciences of the United States of America
It is argued that oxygenic cyanobacteria evolved and radiated shortly before the Makganyene snowball, and could have destroyed a methane greenhouse and triggered a snowball event on time-scales as short as 1 million years.
Geologic history of sea water
- Geology, Environmental Science
Paleontology and biochemistry together may yield fairly definite information, eventually, about the paleochemistry of sea water and atmosphere. Several less conclusive lines of evidence now available…
A revised, hazy methane greenhouse for the Archean Earth.
- Environmental Science, GeologyAstrobiology
Geological and biological evidence suggests that Earth was warm during most of its early history, despite the fainter young Sun. Upper bounds on the atmospheric CO2 concentration in the Late…
The early environment and its evolution on Mars: Implication for life
There is considerable evidence that the early climate of Mars was very different from the inhospitable conditions there today. This early climate was characterized by liquid water on the surface and…
The Early Earth: Physical, Chemical and Biological Development
This volume contains a series of papers that cover a wide range of aspects, including geophysics, structure and tectonics, atmosphere, origin of life, biosphere, deep mantle geochemistry, early…
Evidence from massive siderite beds for a CO2-rich atmosphere before ~ 1.8 billion years ago
- Environmental Science, GeologyNature
It is generally thought that, in order to compensate for lower solar flux and maintain liquid oceans on the early Earth, methane must have been an important greenhouse gas before ∼2.2 billion years…