No climate paradox under the faint early Sun

  title={No climate paradox under the faint early Sun},
  author={M. Rosing and D. Bird and N. Sleep and C. Bjerrum},
Environmental niches in which life first emerged and later evolved on the Earth have undergone dramatic changes in response to evolving tectonic/geochemical cycles and to biologic interventions, as well as increases in the Sun’s luminosity of about 25 to 30 per cent over the Earth’s history. It has been inferred that the greenhouse effect of atmospheric CO2 and/or CH4 compensated for the lower solar luminosity and dictated an Archaean climate in which liquid water was stable in the hydrosphere… Expand
Terrestrial methane fluxes and Proterozoic climate
High concentrations of the greenhouse gases CO2 and CH4 have long been invoked to explain a largely ice-free climate despite lower solar luminosity during the Precambrian. However, recently aExpand
Hydrogen-Nitrogen Greenhouse Warming in Earth's Early Atmosphere
It is shown that with an atmospheric composition consistent with the most recent constraints, the early Earth would have been significantly warmed by H2-N2 collision–induced absorption, key to warming the atmosphere of theEarly Earth. Expand
The evolution of the atmosphere in the Archaean and early Proterozoic
Key steps in atmospheric evolution occurred in the Archaean. The Hadean atmosphere was created by the inorganic processes of volatile accretion from space and degassing from the interior, and thenExpand
Milestones in Early Evolution
During much of its early history Earth was dominated by an oxygen-poor, CO2+CO+methane-rich atmosphere, with several thousand to tens of thousands ppm CO2, inducing high-temperature low-pH acid oceanExpand
CO2 drawdown and cooling at the onset of the Great Oxidation Event recorded in 2.45 Ga paleoweathering crust
Abstract The Archean atmosphere is thought to have been devoid of oxygen but, instead, containing high concentrations of greenhouse gases, such as CO2 and possibly CH4, that were required to keep theExpand
Paleobiological Clues to Early Atmospheric Evolution
The compositional evolution of Earth's early atmosphere reflected a complex interplay between the planetary processes of accretion and differentiation, massive impact events, and voluminousExpand
The Case for a Hot Archean Climate and its Implications to the History of the Biosphere
The case for a much warmer climate on the early Earth than now is presented. The oxygen isotope record in sedimentary chert and the compelling case for a near constant isotopic oxygen composition ofExpand
6.4 – Geologic and Geochemical Constraints on Earth's Early Atmosphere
In this review, the authors examine the geologic and geochemical evidence for the evolution of the atmosphere in the first two billion years of Earth's history. The authors focus on evidence relevantExpand
A CO2 greenhouse efficiently warmed the early Earth and decreased seawater 18O/16O before the onset of plate tectonics
It is shown that high CO2 sequestration fluxes into the oceanic crust, associated with extensive silicification, lowered the δ18Osw of seawater on the early Earth without affecting the Δ’17O, and the controversial long-term trend of increasing ε18O in chemical sediments over Earth’s history partly reflects increasing δ 18Osw due to decreasing atmospheric pCO2. Expand
Investigating the Paleoproterozoic glaciations with 3-D climate modeling
Abstract It is generally assumed that the Earth's surface was warm during most of its early history but that significant cooling occurred between 2.45 and 2.22 Ga leading to the first global andExpand


A revised, hazy methane greenhouse for the Archean Earth.
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 LateExpand
Atmospheric carbon dioxide concentrations before 2.2 billion years ago
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. Expand
Carbon dioxide cycling and implications for climate on ancient Earth
The crustal Urey cycle of CO2 involving silicate weathering and metamorphism acts as a dynamic climate buffer. In this cycle, warmer temperatures speed silicate weathering and carbonate formation,Expand
Evidence from massive siderite beds for a CO2-rich atmosphere before ~ 1.8 billion years ago
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 yearsExpand
Greenhouse warming by CH4 in the atmosphere of early Earth.
It is found that a CH4 mixing ratio of 10(-4) (100 ppmv) or more in Earth's early atmosphere would provide agreement with the paleosol data from 2.3-2.4 Ga, which could have triggered the Earth's first widespread glaciation. Expand
A lower limit for atmospheric carbon dioxide levels 3.2 billion years ago
Here, model equilibrium reactions for weathering rinds on 3.2-Gyr-old river gravels are used to show that the presence of iron-rich carbonate relative to common clay minerals requires a minimum partial pressure of carbon dioxide several times higher than present-day values. Expand
Niches of the pre‐photosynthetic biosphere and geologic preservation of Earth's earliest ecology
The tree of terrestrial life probably roots in non-photosynthetic microbes. Chemoautotrophs were the first primary producers, and the globally dominant niches in terms of primary productivity wereExpand
Paleoclimates, ocean depth, and the oxygen isotopic composition of seawater
A recurrent interpretation of ancient climate based on the oxygen isotopic composition of marine carbonates and cherts suggests that Earth's climate was substantially warmer in the distant past andExpand
Rise of atmospheric oxygen and the “upside‐down” Archean mantle
[1] The establishment of an oxygen-rich atmosphere dramatically altered the evolution of life on Earth. Most of the recent discussion of the topic has been focused on the timing of the event ratherExpand
The life span of the biosphere revisited
A more elaborate model that includes a more accurate treatment of the greenhouse effect of CO2, a biologically mediated weathering parameterization, and the realization that C4 photosynthesis can persist to much lower concentrations of atmospheric CO2 is found to find that a C4-plant-based biosphere could survive for at least another 0.9 Gyr to 1.5 Gyr after the present time. Expand