scholarly journals Scientific drilling and the evolution of the earth system: climate, biota, biogeochemistry and extreme systems

2013 ◽  
Vol 16 ◽  
pp. 63-72 ◽  
Author(s):  
G. S. Soreghan ◽  
A. S. Cohen

Abstract. A US National Science Foundation-funded workshop occurred 17–19 May 2013 at the University of Oklahoma to stimulate research using continental scientific drilling to explore earth's sedimentary, paleobiological and biogeochemical record. Participants submitted 3-page "pre-proposals" to highlight projects that envisioned using drill-core studies to address scientific issues in paleobiology, paleoclimatology, stratigraphy and biogeochemistry, and to identify locations where key questions can best be addressed. The workshop was also intended to encourage US scientists to take advantage of the exceptional capacity of unweathered, continuous core records to answer important questions in the history of earth's sedimentary, biogeochemical and paleobiologic systems. Introductory talks on drilling and coring methods, plus best practices in core handling and curation, opened the workshop to enable all to understand the opportunities and challenges presented by scientific drilling. Participants worked in thematic breakout sessions to consider questions to be addressed using drill cores related to glacial–interglacial and icehouse–greenhouse transitions, records of evolutionary events and extinctions, records of major biogeochemical events in the oceans, reorganization of earth's atmosphere, Lagerstätte and exceptional fossil biota, records of vegetation–landscape change, and special sampling requirements, contamination, and coring tool concerns for paleobiology, geochemistry, geochronology, and stratigraphy–sedimentology studies. Closing discussions at the workshop focused on the role drilling can play in studying overarching science questions about the evolution of the earth system. The key theme, holding the most impact in terms of societal relevance, is understanding how climate transitions have driven biotic change, and the role of pristine, stratigraphically continuous cores in advancing our understanding of this linkage. Scientific drilling, and particularly drilling applied to continental targets, provides unique opportunities to obtain continuous and unaltered material for increasingly sophisticated analyses, tapping the entire geologic record (extending through the Archean), and probing the full dynamic range of climate change and its impact on biotic history.

Author(s):  
John J. W. Rogers ◽  
M. Santosh

Continents affect the earth’s climate because they modify global wind patterns, control the paths of ocean currents, and absorb less heat than seawater. Throughout earth history the constant movement of continents and the episodic assembly of supercontinents has influenced both global climate and the climates of individual continents. In this chapter we discuss both present climate and the history of climate as far back in the geologic record as we can draw inferences. We concentrate on longterm changes that are affected by continental movements and omit discussion of processes with periodicities less than about 20,000 years. We refer readers to Clark et al. (1999) and Cronin (1999) if they are interested in such short-term processes as El Nino, periodic variations in solar irradiance, and Heinrich events. The chapter is divided into three sections. The first section describes the processes that control climate on the earth and includes a discussion of possible causes of glaciation that occurred over much of the earth at more than one time in the past. The second section investigates the types of evidence that geologists use to infer past climates. They include specific rock types that can form only under restricted climatic conditions, varieties of individual fossils, diversity of fossil populations, and information that the 18O/16O isotopic system can provide about temperatures of formation of ancient sediments. The third section recounts the history of the earth’s climate and relates changes to the growth and movement of continents. This history takes us from the Archean, when climates are virtually unknown, through various stages in the evolution of organic life, and ultimately to the causes of the present glaciation in both the north and the south polar regions. The earth’s climate is controlled both by processes that would operate even if continents did not exist and also by the positions and topographies of continents. We begin with the general controls, then discuss the specific effects of continents, and close with a brief discussion of processes that cause glaciation. The general climate of the earth is determined by the variation in the amount of sunshine received at different latitudes, by the earth’s rotation, and by the amount of arriving solar energy that is retained in the atmosphere.


2018 ◽  
Vol 5 (2) ◽  
pp. 107-119 ◽  
Author(s):  
Kyle Nichols ◽  
Bina Gogineni

The Anthropocene, generally defined, is the time when human activities have a significant impact on the Earth System. However, the natural sciences, the humanities, and the social sciences have different understandings of how and when human activities affected the Earth System. Humanities and social science scholars tend to approach the Anthropocene from a wide range of moral-political concerns including differential responsibility for the change in the Earth System and social implications going forward. Geologists, on the other hand, see their work as uninfluenced by such considerations, instead concerning themselves with empirical data that might point to a ‘golden spike’ in the geologic record – the spike indicating a change in the Earth System. Thus, the natural sciences and the humanities/social sciences are incongruent in two important ways: (1) different motivations for establishing a new geologic era, and (2) different parameters for identifying it. The Anthropocene discussions have already hinted at a paradigm shift in how to define geologic time periods. Several articles suggest a mid-20th century commencement of the Anthropocene based on stratigraphic relationships identified in concert with knowledge of human history. While some geologists in the Anthropocene Working Group have stated that the official category should be useful well beyond geology, they continue to be guided by the stratigraphic conventions of defining the epoch. However, the methods and motivations that govern stratigraphers are different from those that govern humanists and social scientists. An Anthropocene defined by stratigraphic convention would supersede many of the humanities/social science perspectives that perhaps matter more to mitigating and adapting to the effects of humans on Earth’s System. By this reasoning, the impetus for defining the Anthropocene ought to be interdisciplinary, as traditional geologic criteria for defining the temporal scale might not meet the aspirations of a broad range of Anthropocene thinkers.


2020 ◽  
Vol 10 (4) ◽  
pp. 20190106 ◽  
Author(s):  
Jonathan L. Payne ◽  
Aviv Bachan ◽  
Noel A. Heim ◽  
Pincelli M. Hull ◽  
Matthew L. Knope

The half-billion-year history of animal evolution is characterized by decreasing rates of background extinction. Earth's increasing habitability for animals could result from several processes: (i) a decrease in the intensity of interactions among species that lead to extinctions; (ii) a decrease in the prevalence or intensity of geological triggers such as flood basalt eruptions and bolide impacts; (iii) a decrease in the sensitivity of animals to environmental disturbance; or (iv) an increase in the strength of stabilizing feedbacks within the climate system and biogeochemical cycles. There is no evidence that the prevalence or intensity of interactions among species or geological extinction triggers have decreased over time. There is, however, evidence from palaeontology, geochemistry and comparative physiology that animals have become more resilient to an environmental change and that the evolution of complex life has, on the whole, strengthened stabilizing feedbacks in the climate system. The differential success of certain phyla and classes appears to result, at least in part, from the anatomical solutions to the evolution of macroscopic size that were arrived at largely during Ediacaran and Cambrian time. Larger-bodied animals, enabled by increased anatomical complexity, were increasingly able to mix the marine sediment and water columns, thus promoting stability in biogeochemical cycles. In addition, body plans that also facilitated ecological differentiation have tended to be associated with lower rates of extinction. In this sense, Cambrian solutions to Cambrian problems have had a lasting impact on the trajectory of complex life and, in turn, fundamental properties of the Earth system.


2020 ◽  
Vol 69 ◽  
pp. 109-131
Author(s):  
R. W. Ogden

Peter Chadwick studied mathematics as an undergraduate at the University of Manchester, graduating with first-class honours in 1952, from where he moved to Cambridge and completed a PhD on the thermal history of the Earth in the Department of Geodesy and Geophysics under the supervision of Dr Robert Stoneley. His research then developed to focus primarily on the propagation of waves, and he made a major contribution to the mathematical theory of elastic wave propagation and became a world-leading authority in this area. He also made fundamental advances in the modelling of the thermo-elastic properties of rubberlike materials. At the University of East Anglia, where he was a professor for 26 years, he was the driving force behind the development of a research group in theoretical mechanics in the School of Mathematics and Physics, leading by example and supporting and encouraging fellow faculty members, especially the younger staff, academic visitors and students. He gave considerable service to the University of East Anglia in a number of capacities, including a period as Dean of the School, and to the scientific community, through substantial journal editorial activities and as a member of several national and international committees.


1992 ◽  
Vol 9 (3) ◽  
pp. v-vii
Author(s):  
Sayyid M. Syeed

Our first paper, by Abdul Khaliq, discusses the Islamic view of faith andmorality. The author shows how one’s faith in God, from the Qur’anic perspective,is a commitment, as it implies both a whole metaphysics and anentire philosophy of life. In our personal lives, we need a healthy metaphysicsfor our moral behavior. Similarly, the sciences also need a metaphysicaloutlook, for this will provide significant pointers as to the direction in whichscientific progress should advance. Abdul Khaliq further argues for a closerelationship between the physical sciences and metaphysics. He assures usthat this intimacy will not jeopardize the positive sciences’ autonomy andtheir freedom of inquiry. His paper ends with the assertions that the cause ofmoral degeneration is to be sought in the loss of digious faith and that arejuvenation of religious faith can automatically reinstate morality.The Department of History of Science at the University of Oklahoma,Norman, OK, organized a conference on “Tradition, Transmission, Transformation:An Ancient Mechanics in Islamic and Occidental Culture,” held on6-7 March 1992. It was here that J. L. Berggren made an outstandingpresentation entitled “Islamic Acquisition of the Foreign Sciences: A CulturalPerspective.“ We are publishing a revised version of this paper here. Berggrenillustrates how cultural factots may have affected the Islamic world’sreception and acquisition of foreign sciences. The process of Islamizing themathematical sciences inherited from the classical Greeks is instructive, forby studying it we realize that Muslim scientists were tesponding to the needs,concerns, and criticisms of a civilization profoundly different from that ofclassical Greece. Berggren shows how Islamic mathematics was not just goodGreek mathematics done by people who happened to write in Arabic. He alsosuggests that it is important for us to understand the terms on which Islamicculture of that time approached classical Greek culture. In fact, to spell outthese terms of Islamization is even more crucial for us today, as we seek tofacilitate the adoption of modern sciences into an Islamic worldview.In his keynote address to the International Seminar on Malik Bennabi,Anwar Ibmhim complained that “it is an indictment of our parochialism thatBennabi has been neglected because he wrote in French. It is an even greaterindictment that he is neglected because he was an individual thinker and notthe idealogue of a movement. Neither is sufficient teason for original thoughtto be marginalized.” We need to correct this situation and make an extra effortto ensure that Bennabi’s ideas accessible to researchers and also toencourage more translations, discussions, and writings of this very important ...


Author(s):  
John J. W. Rogers ◽  
M. Santosh

Alfred Wegener never set out to be a geologist. With an education in meteorology and astronomy, his career seemed clear when he was appointed Lecturer in those subjects at the University of Marburg, Germany. It wasn’t until 1912, when Wegener was 32, that he published a paper titled “Die Entstehung der Kontinente” (The origin of the continents) in a recently founded journal called Geologische Rundschau. This meteorologist had just fired the opening shot in a revolution that would change the way that geologists thought about the earth. In a series of publications and talks both before and after World War I, Wegener pressed the idea that continents moved around the earth independently of each other and that the present continents resulted from the splitting of a large landmass (we now call it a “supercontinent”) that previously contained all of the world’s continents. After splitting, they moved to their current positions, closing oceans in front of them and opening new oceans behind them. Wegener and his supporters referred to this process as “continental drift.” The proposal that continents moved around the earth led to a series of investigations and ideas that occupied much of the 20th century. They are now grouped as a set of concepts known as “plate tectonics.” We begin this chapter with an investigation of the history of this development, starting with ideas that preceded Wegener’s proposal. This is followed by a section that describes the reactions of different geologists to the idea of continental drift, including some comments that demonstrate the rancorous nature of the debate. The next section discusses developments between Wegener’s proposal and 1960, when Harry Hess suggested that the history of modern ocean basins is consistent with the concept of drifting continents. We finish the chapter with a brief description of seafloor spreading and leave a survey of plate tectonics to chapter 2. Although Wegener is credited with first proposing continental drift, some tenuous suggestions had already been made. We summarize some of this early history from LeGrand (1988).


2021 ◽  
Vol 14 (7) ◽  
pp. 4187-4223
Author(s):  
Markus Adloff ◽  
Andy Ridgwell ◽  
Fanny M. Monteiro ◽  
Ian J. Parkinson ◽  
Alexander J. Dickson ◽  
...  

Abstract. The metals strontium (Sr), lithium (Li), osmium (Os) and calcium (Ca), together with their isotopes, are important tracers of weathering and volcanism – primary processes which shape the long-term cycling of carbon and other biogeochemically important elements at the Earth's surface. Traditionally, because of their long residence times in the ocean, isotopic shifts in these four elements observed in the geologic record are almost exclusively interpreted with the aid of isotope-mixing, tracer-specific box models. However, such models may lack a mechanistic description of the links between the cycling of the four metals to other geochemically relevant elements, particularly carbon, or climate. Here we develop and evaluate an implementation of Sr, Li, Os and Ca isotope cycling in the Earth system model cGENIE. The model offers the possibility to study the dynamics of these metal systems alongside other more standard biogeochemical cycles, as well as their relationship with changing climate. We provide examples of how to apply this new model capability to investigate Sr, Li, Os and Ca isotope dynamics and responses to environmental change, for which we take the example of massive carbon release to the atmosphere.


Sign in / Sign up

Export Citation Format

Share Document