scholarly journals The Archean atmosphere

2020 ◽  
Vol 6 (9) ◽  
pp. eaax1420 ◽  
Author(s):  
David C. Catling ◽  
Kevin J. Zahnle
Keyword(s):  
Carbon Cycle ◽  
Greenhouse Gas ◽  
Solid Earth ◽  
Atmospheric Composition ◽  
Detailed Understanding ◽  
Average Surface ◽  
Substantial Loss ◽  
Mass Fractionation ◽  
The Earth ◽  
Surface Temperatures

The atmosphere of the Archean eon—one-third of Earth’s history—is important for understanding the evolution of our planet and Earth-like exoplanets. New geological proxies combined with models constrain atmospheric composition. They imply surface O2 levels <10−6 times present, N2 levels that were similar to today or possibly a few times lower, and CO2 and CH4 levels ranging ~10 to 2500 and 102 to 104 times modern amounts, respectively. The greenhouse gas concentrations were sufficient to offset a fainter Sun. Climate moderation by the carbon cycle suggests average surface temperatures between 0° and 40°C, consistent with occasional glaciations. Isotopic mass fractionation of atmospheric xenon through the Archean until atmospheric oxygenation is best explained by drag of xenon ions by hydrogen escaping rapidly into space. These data imply that substantial loss of hydrogen oxidized the Earth. Despite these advances, detailed understanding of the coevolving solid Earth, biosphere, and atmosphere remains elusive, however.

The Earth’s Impact on Life and Life’s Impact on the Earth

2021 ◽  
pp. 229-256
Author(s):  
Elisabeth Ervin-Blankenheim
Keyword(s):  
Climate Change ◽  
Carbon Cycle ◽  
Solid Earth ◽  
Plate Tectonics ◽  
Time Perspective ◽  
Current Situation ◽  
Critical Systems ◽  
Deep Time ◽  
The Earth ◽  
Current Concerns

This chapter weaves together the three threads that make up the fundamental geologic principles: geologic time, plate tectonics, and evolution. The chapter examines their impact on life on the Earth and, in turn, biological life’s imprint on the planet. Each system, or sphere, of the Earth, water, air, solid Earth, and life, are interdependent. At the intersection of these spheres are critical systems, such as soil and the carbon cycle, both of which support life. The current situation on the planet, with diminishing resources and population numbers and changes in climate, are current concerns. The interrelated web of life in response to climate change and implications for the future benefits from a deep-time perspective with geology as a framework. Past hothouse times, tipping points, and understanding how the Earth works as well as the biography of the Earth through the lens of geology, can go far as a guide to future conditions on the planet—to listen to the song of the Earth.

scholarly journals Life among the Craters

2004 ◽  
Vol 213 ◽  
pp. 199-202
Author(s):  
Harrison H. Schmitt
Keyword(s):  
Terrestrial Planets ◽  
The Moon ◽  
Detailed Understanding ◽  
The Earth ◽  
Planetary Mass ◽  
End Members

The Moon forms one end-member in the planetary mass series Earth-Venus-Mars-Mercury-Asteroids-Moon (Weissman 1999). Having a detailed understanding of the nature and evolution of the two end-members of this series, rather than of just the Earth, has increased the value of other data and inferences by orders of magnitude. As a consequence of obtaining an understanding of the evolution of a second planet, we now can look at other terrestrial planets with far greater insight than ever would have been possible otherwise (Fig. 1).

scholarly journals Geosystemics and Earthquakes

2018 ◽  
Author(s):  
Angelo De Santis ◽  
Gianfranco Cianchini ◽  
Rita Di Giovambattista ◽  
Cristoforo Abbattista ◽  
Lucilla Alfonsi ◽  
...  
Keyword(s):  
Dynamical System ◽  
Solid Earth ◽  
Case Studies ◽  
Central Italy ◽  
Point Of View ◽  
Earth System ◽  
Complex Dynamical System ◽  
The Earth ◽  
Earth’S Interior

Abstract. Geosystemics (De Santis 2009, 2014) studies the Earth system as a whole focusing on the possible coupling among the Earth layers (the so called geo-layers), and using universal tools to integrate different methods that can be applied to multi-parameter data, often taken on different platforms. Its main objective is to understand the particular phenomenon of interest from a holistic point of view. In this paper we will deal with earthquakes, considered as a long term chain of processes involving, not only the interaction between different components of the Earth’s interior, but also the coupling of the solid earth with the above neutral and ionized atmosphere, and finally culminating with the main rupture along the fault of concern (De Santis et al., 2015a). Some case studies (particular emphasis is given to recent central Italy earthquakes) will be discussed in the frame of the geosystemic approach for better understanding the physics of the underlying complex dynamical system.

scholarly journals Reviews and syntheses: Flying the satellite into your model: on the role of observation operators in constraining models of the Earth system and the carbon cycle

2017 ◽  
Vol 14 (9) ◽  
pp. 2343-2357 ◽  
Author(s):  
Thomas Kaminski ◽  
Pierre-Philippe Mathieu
Keyword(s):  
Data Assimilation ◽  
Carbon Cycle ◽  
Automatic Differentiation ◽  
Satellite Observations ◽  
Spectral Radiance ◽  
Special Focus ◽  
Earth System ◽  
The Earth ◽  
Retrieval Scheme

Abstract. The vehicles that fly the satellite into a model of the Earth system are observation operators. They provide the link between the quantities simulated by the model and the quantities observed from space, either directly (spectral radiance) or indirectly estimated through a retrieval scheme (biogeophysical variables). By doing so, observation operators enable modellers to properly compare, evaluate, and constrain their models with the model analogue of the satellite observations. This paper provides the formalism and a few examples of how observation operators can be used in combination with data assimilation techniques to better ingest satellite products in a manner consistent with the dynamics of the Earth system expressed by models. It describes commonalities and potential synergies between assimilation and classical retrievals. This paper explains how the combination of observation operators and their derivatives (linearizations) form powerful research tools. It introduces a technique called automatic differentiation that greatly simplifies both the development and the maintenance of code for the evaluation of derivatives. Throughout this paper, a special focus lies on applications to the carbon cycle.

scholarly journals Twenty-First-Century Compatible CO2 Emissions and Airborne Fraction Simulated by CMIP5 Earth System Models under Four Representative Concentration Pathways

2013 ◽  
Vol 26 (13) ◽  
pp. 4398-4413 ◽  
Author(s):  
Chris Jones ◽  
Eddy Robertson ◽  
Vivek Arora ◽  
Pierre Friedlingstein ◽  
Elena Shevliakova ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Climate Models ◽  
Coupled Model ◽  
Co2 Concentration ◽  
Atmospheric Composition ◽  
System Component ◽  
Anthropogenic Emissions ◽  
Carbon Uptake ◽  
Earth System ◽  
Representative Concentration Pathways

Abstract The carbon cycle is a crucial Earth system component affecting climate and atmospheric composition. The response of natural carbon uptake to CO2 and climate change will determine anthropogenic emissions compatible with a target CO2 pathway. For phase 5 of the Coupled Model Intercomparison Project (CMIP5), four future representative concentration pathways (RCPs) have been generated by integrated assessment models (IAMs) and used as scenarios by state-of-the-art climate models, enabling quantification of compatible carbon emissions for the four scenarios by complex, process-based models. Here, the authors present results from 15 such Earth system GCMs for future changes in land and ocean carbon storage and the implications for anthropogenic emissions. The results are consistent with the underlying scenarios but show substantial model spread. Uncertainty in land carbon uptake due to differences among models is comparable with the spread across scenarios. Model estimates of historical fossil-fuel emissions agree well with reconstructions, and future projections for representative concentration pathway 2.6 (RCP2.6) and RCP4.5 are consistent with the IAMs. For high-end scenarios (RCP6.0 and RCP8.5), GCMs simulate smaller compatible emissions than the IAMs, indicating a larger climate–carbon cycle feedback in the GCMs in these scenarios. For the RCP2.6 mitigation scenario, an average reduction of 50% in emissions by 2050 from 1990 levels is required but with very large model spread (14%–96%). The models also disagree on both the requirement for sustained negative emissions to achieve the RCP2.6 CO2 concentration and the success of this scenario to restrict global warming below 2°C. All models agree that the future airborne fraction depends strongly on the emissions profile with higher airborne fraction for higher emissions scenarios.

The Earth energy imbalance – new advances and remaining challenges

2021 ◽  
Author(s):  
Karina von Schuckmann
Keyword(s):  
Global Climate ◽  
Research Effort ◽  
Atmospheric Composition ◽  
Multidisciplinary Research ◽  
Energy Imbalance ◽  
The Past ◽  
The Earth ◽  
Multiple Measurements ◽  
Composition Changes ◽  
Past Half

&lt;p&gt;Human-induced atmospheric composition changes cause a radiative imbalance at the top of the atmosphere which is driving global warming. This simple number, the Earth energy imbalance (EEI), is the most fundamental metric that the scientific community and public must be aware of as the measure of how well the world is doing in the task of bringing climate change under control. Combining multiple measurements and approaches in an optimal way holds considerable promise for estimating EEI and continued quantification and reduced uncertainties can be best achieved through the maintenance of the current global climate observing system, its extension into areas of gaps in the sampling, advance on instrumental limitations, and the establishment of an international framework for concerted multidisciplinary research effort. This talk will provide an overview on the different approaches and their challenges for estimating the EEI. A particular emphasis will be drawn on the heat gain of the Earth system over the past half of a century &amp;#8211; and particularly how much and where the heat is distributed &amp;#8211; which is fundamental to understanding how this affects warming ocean, atmosphere and land; rising surface temperature; sea level; and loss of grounded and floating ice, which are critical concerns for society.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

Introduction

2004 ◽  
Author(s):  
Robert A. Berner
Keyword(s):  
Climate Change ◽  
Carbon Dioxide ◽  
Carbon Cycle ◽  
Global Climate ◽  
Geological Time ◽  
Short Term ◽  
Quaternary Period ◽  
Geological Time Scale ◽  
The Earth

The cycle of carbon is essential to the maintenance of life, to climate, and to the composition of the atmosphere and oceans. What is normally thought of as the “carbon cycle” is the transfer of carbon between the atmosphere, the oceans, and life. This is not the subject of interest of this book. To understand this apparently confusing statement, it is necessary to separate the carbon cycle into two cycles: the short-term cycle and the long-term cycle. The “carbon cycle,” as most people understand it, is represented in figure 1.1. Carbon dioxide is taken up via photosynthesis by green plants on the continents or phytoplankton in the ocean. On land carbon is transferred to soils by the dropping of leaves, root growth, and respiration, the death of plants, and the development of soil biota. Land herbivores eat the plants, and carnivores eat the herbivores. In the oceans the phytoplankton are eaten by zooplankton that are in turn eaten by larger and larger organisms. The plants, plankton, and animals respire CO2. Upon death the plants and animals are decomposed by microorganisms with the ultimate production of CO2. Carbon dioxide is exchanged between the oceans and atmosphere, and dissolved organic matter is carried in solution by rivers from soils to the sea. This all constitutes the shortterm carbon cycle. The word “short-term” is used because the characteristic times for transferring carbon between reservoirs range from days to tens of thousands of years. Because the earth is more than four billion years old, this is short on a geological time scale. As the short-term cycle proceeds, concentrations of the two principal atmospheric gases, CO2 and CH4, can change as a result of perturbations of the cycle. Because these two are both greenhouse gases—in other words, they adsorb outgoing infrared radiation from the earth surface—changes in their concentrations can involve global warming and cooling over centuries and many millennia. Such changes have accompanied global climate change over the Quaternary period (past 2 million years), although other factors, such as variations in the receipt of solar radiation due to changes in characteristics of the earth’s orbit, have also contributed to climate change.

scholarly journals Defining Genomic and Predicted Metabolic Features of the Acetobacterium Genus

mSystems ◽  
2020 ◽  
Vol 5 (5) ◽  
Author(s):  
Daniel E. Ross ◽  
Christopher W. Marshall ◽  
Djuna Gulliver ◽  
Harold D. May ◽  
R. Sean Norman
Keyword(s):  
Carbon Cycle ◽  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Anaerobic Bacteria ◽  
Global Carbon Cycle ◽  
Acetyl Coa ◽  
Gas Emissions ◽  
Autotrophic Metabolism ◽  
Fuels And Chemicals ◽  
Global Carbon

Acetogens are anaerobic bacteria capable of fixing CO2 or CO to produce acetyl-CoA and ultimately acetate using the Wood-Ljungdahl pathway (WLP). This autotrophic metabolism plays a major role in the global carbon cycle and, if harnessed, can help reduce greenhouse gas emissions. Overall, the data presented here provide a framework for examining the ecology and evolution of the Acetobacterium genus and highlight the potential of these species as a source for production of fuels and chemicals from CO2 feedstocks.

Sign in / Sign up

Export Citation Format

Share Document