scholarly journals A revised lower estimate of ozone columns during Earth’s oxygenated history

2022 ◽  
Vol 9 (1) ◽  
Author(s):  
G. J. Cooke ◽  
D. R. Marsh ◽  
C. Walsh ◽  
B. Black ◽  
J.-F. Lamarque
Keyword(s):  
Climate Model ◽  
Three Dimensional ◽  
Time Varying ◽  
Geological Evidence ◽  
Earth’S Atmosphere ◽  
Great Oxidation Event ◽  
Climate Simulations ◽  
Order Of Magnitude ◽  
History Of ◽  
Earth's Atmosphere

The history of molecular oxygen (O 2 ) in Earth’s atmosphere is still debated; however, geological evidence supports at least two major episodes where O 2 increased by an order of magnitude or more: the Great Oxidation Event (GOE) and the Neoproterozoic Oxidation Event. O 2 concentrations have likely fluctuated (between 10 −3 and 1.5 times the present atmospheric level) since the GOE ∼2.4 Gyr ago, resulting in a time-varying ozone (O 3 ) layer. Using a three-dimensional chemistry-climate model, we simulate changes in O 3 in Earth’s atmosphere since the GOE and consider the implications for surface habitability, and glaciation during the Mesoproterozoic. We find lower O 3 columns (reduced by up to 4.68 times for a given O 2 level) compared to previous work; hence, higher fluxes of biologically harmful UV radiation would have reached the surface. Reduced O 3 leads to enhanced tropospheric production of the hydroxyl radical (OH) which then substantially reduces the lifetime of methane (CH 4 ). We show that a CH 4 supported greenhouse effect during the Mesoproterozoic is highly unlikely. The reduced O 3 columns we simulate have important implications for astrobiological and terrestrial habitability, demonstrating the relevance of three-dimensional chemistry-climate simulations when assessing paleoclimates and the habitability of faraway worlds.

History of the Earth’s Atmosphere

1987 ◽  
Author(s):  
Michael I. Budyko ◽  
Alexander B. Ronov ◽  
Alexander L. Yanshin
Keyword(s):  
Earth’S Atmosphere ◽  
History Of ◽  
Earth's Atmosphere

scholarly journals In-Situ Cosmogenic 14C: Production and Examples of its Unique Applications in Studies of Terrestrial and Extraterrestrial Processes

Radiocarbon ◽  
2001 ◽  
Vol 43 (2B) ◽  
pp. 731-742 ◽  
Author(s):  
D Lal ◽  
A J T Jull
Keyword(s):  
Half Life ◽  
Earth Science ◽  
Chemical Properties ◽  
Radioactive Isotopes ◽  
Earth’S Atmosphere ◽  
The Earth ◽  
Wide Range ◽  
History Of ◽  
Earth's Atmosphere

Nuclear interactions of cosmic rays produce a number of stable and radioactive isotopes on the earth (Lai and Peters 1967). Two of these, 14C and 10Be, find applications as tracers in a wide variety of earth science problems by virtue of their special combination of attributes: 1) their source functions, 2) their half-lives, and 3) their chemical properties. The radioisotope, 14C (half-life = 5730 yr) produced in the earth's atmosphere was the first to be discovered (Anderson et al. 1947; Libby 1952). The next longer-lived isotope, also produced in the earth's atmosphere, 10Be (half-life = 1.5 myr) was discovered independently by two groups within a decade (Arnold 1956; Goel et al. 1957; Lal 1991a). Both the isotopes are produced efficiently in the earth's atmosphere, and also in solids on the earth's surface. Independently and jointly they serve as useful tracers for characterizing the evolutionary history of a wide range of materials and artifacts. Here, we specifically focus on the production of 14C in terrestrial solids, designated as in-situ-produced 14C (to differentiate it from atmospheric 14C, initially produced in the atmosphere). We also illustrate the application to several earth science problems. This is a relatively new area of investigations, using 14C as a tracer, which was made possible by the development of accelerator mass spectrometry (AMS). The availability of the in-situ 14C variety has enormously enhanced the overall scope of 14C as a tracer (singly or together with in-situ-produced 10Be), which eminently qualifies it as a unique tracer for studying earth sciences.

History of the Earth's Atmosphere

Eos ◽  
1988 ◽  
Vol 69 (38) ◽  
pp. 869 ◽  
Author(s):  
Robert A. Berner
Keyword(s):  
Earth’S Atmosphere ◽  
History Of ◽  
Earth's Atmosphere

Extraordinary climates of Earth-like planets: three-dimensional climate simulations at extreme obliquity

2003 ◽  
Vol 2 (1) ◽  
pp. 1-19 ◽  
Author(s):  
Darren M. Williams ◽  
David Pollard
Keyword(s):  
General Circulation ◽  
Climate Model ◽  
Three Dimensional ◽  
Terrestrial Planet ◽  
Present Value ◽  
Seasonal Snow ◽  
Climate Simulations ◽  
Nearby Stars ◽  
Earth Like Planets ◽  
The Tropics

A three-dimensional general-circulation climate model is used to simulate climates of Earth-like planets with extreme axial tilts (i.e. ‘obliquities’). While no terrestrial-planet analogue exists in the solar system, planets with steeply inclined spin axes may be common around nearby stars. Here we report the results of 12 numerical experiments with Earth-like planets having different obliquities (from 0° to 85°), continental geographies, and levels of the important greenhouse gas, CO2. Our simulations show intense seasonality in surface temperatures for obliquities [ges ]54°, with temperatures reaching 80–100 °C over the largest middle- and high-latitude continents around the summer solstice. Net annual warming at high latitudes is countered by reduced insolation and colder temperatures in the tropics, which maintains the global annual mean temperature of our planets to within a few degrees of 14 °C. Under reduced insolation, seasonal snow covers some land areas near the equator; however no significant net annual accumulation of snow or ice occurs in any of our runs with obliquity exceeding the present value, in contrast to some previous studies. None of our simulated planets were warm enough to develop a runaway greenhouse or cold enough to freeze over completely; therefore, most real Earth-like planets should be hospitable to life at high obliquity.

The Great Oxidation

2017 ◽  
Author(s):  
Donald Eugene Canfield
Keyword(s):  
Oxygen Content ◽  
Atmospheric Chemistry ◽  
Tipping Point ◽  
Earth’S Atmosphere ◽  
Great Oxidation Event ◽  
Earth's Atmosphere ◽  
Geologic Record

This chapter deals with the “great oxidation event” (GOE), which represents a quantum shift in the oxygen content of the atmosphere. It suggests that the GOE represents the evolution of cyanobacteria. According to the geologic record, the oxygen content of Earth's atmosphere increased dramatically around 2.3 billion years ago. Since cyanobacteria likely evolved much earlier, it does not appear that a well-oxygenated atmosphere is a necessary or immediate consequence of the activities of oxygen-producing organisms. Atmospheric chemistry is a slave to the dynamics of the mantle, as the interior and exterior of the planet are connected in a profound way. Indeed, it took half of Earth's history for the mantle to quiet to point where oxygen could accumulate. This, however, represented a watershed, a tipping point if you will, where the chemistry of Earth's surface was forever altered.

Oxygen

2017 ◽  
Author(s):  
Donald Eugene Canfield
Keyword(s):  
Scientific Evidence ◽  
Earth’S Atmosphere ◽  
The Earth ◽  
Evolution Of Life ◽  
History Of ◽  
Earth's Atmosphere ◽  
Book Covers ◽  
Over Time ◽  
The Way

The air we breathe is 21 percent oxygen, an amount higher than on any other known world. While we may take our air for granted, Earth was not always an oxygenated planet. How did it become this way? This book covers this vast history, emphasizing its relationship to the evolution of life and the evolving chemistry of the Earth. The book guides readers through the various lines of scientific evidence, considers some of the wrong turns and dead ends along the way, and highlights the scientists and researchers who have made key discoveries in the field. Showing how Earth's atmosphere developed over time, the book takes readers on a remarkable journey through the history of the oxygenation of our planet.

4. Atmospheric composition

2017 ◽  
pp. 65-92
Author(s):  
Paul I. Palmer
Keyword(s):  
Ultraviolet Radiation ◽  
Atmospheric Aerosols ◽  
Stratospheric Ozone ◽  
Ultraviolet B ◽  
Atmospheric Composition ◽  
Earth’S Atmosphere ◽  
Stratospheric Ozone Layer ◽  
History Of ◽  
Earth's Atmosphere ◽  
The Impact

Nitrogen, oxygen, and argon represent more than 99.9% of the air we breathe. But Earth’s atmosphere hasn’t always had that composition—it is on at least its third distinctive atmosphere. ‘Atmospheric composition’ provides a brief history of Earth’s atmosphere, before considering the two most important regions of the atmosphere for human survival—the stratosphere and troposphere. The stratospheric ozone layer shields harmful ultraviolet-B light penetrating to the surface, thereby protecting humans and ecosystems from harmful ultraviolet radiation. The troposphere is where billions of people live and breathe. It is also where air pollutants are emitted, wildfires burn, vegetation grows, and where the oceans exchange gases. The impact of atmospheric aerosols and greenhouse gases is also discussed.

scholarly journals Short- and medium-term atmospheric constituent effects of very large solar proton events

2008 ◽  
Vol 8 (3) ◽  
pp. 765-785 ◽  
Author(s):  
C. H. Jackman ◽  
D. R. Marsh ◽  
F. M. Vitt ◽  
R. R. Garcia ◽  
E. L. Fleming ◽  
...  
Keyword(s):  
Climate Model ◽  
Michelson Interferometer ◽  
Geomagnetic Latitude ◽  
High Energy ◽  
Solar Proton ◽  
Atmospheric Effects ◽  
Medium Term ◽  
Earth’S Atmosphere ◽  
Earth's Atmosphere ◽  
Solar Proton Events

Abstract. Solar eruptions sometimes produce protons, which impact the Earth's atmosphere. These solar proton events (SPEs) generally last a few days and produce high energy particles that precipitate into the Earth's atmosphere. The protons cause ionization and dissociation processes that ultimately lead to an enhancement of odd-hydrogen and odd-nitrogen in the polar cap regions (>60° geomagnetic latitude). We have used the Whole Atmosphere Community Climate Model (WACCM3) to study the atmospheric impact of SPEs over the period 1963–2005. The very largest SPEs were found to be the most important and caused atmospheric effects that lasted several months after the events. We present the short- and medium-term (days to a few months) atmospheric influence of the four largest SPEs in the past 45 years (August 1972; October 1989; July 2000; and October–November 2003) as computed by WACCM3 and observed by satellite instruments. Polar mesospheric NOx (NO+NO2) increased by over 50 ppbv and mesospheric ozone decreased by over 30% during these very large SPEs. Changes in HNO3, N2O5, ClONO2, HOCl, and ClO were indirectly caused by the very large SPEs in October–November 2003, were simulated by WACCM3, and previously measured by Envisat Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). WACCM3 output was also represented by sampling with the MIPAS averaging kernel for a more valid comparison. Although qualitatively similar, there are discrepancies between the model and measurement with WACCM3 predicted HNO3 and ClONO2 enhancements being smaller than measured and N2O5 enhancements being larger than measured. The HOCl enhancements were fairly similar in amounts and temporal variation in WACCM3 and MIPAS. WACCM3 simulated ClO decreases below 50 km, whereas MIPAS mainly observed increases, a very perplexing difference. Upper stratospheric and lower mesospheric NOx increased by over 10 ppbv and was transported during polar night down to the middle stratosphere in several weeks past the SPE. The WACCM3 simulations confirmed the SH HALOE observations of enhanced NOx in September 2000 as a result of the July 2000 SPE and the NH SAGE II observations of enhanced NO2 in March 1990 as a result of the October 1989 SPEs.

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