Quotes & Sayings


We, and creation itself, actualize the possibilities of the God who sustains the world, towards becoming in the world in a fuller, more deeper way. - R.E. Slater

There is urgency in coming to see the world as a web of interrelated processes of which we are integral parts, so that all of our choices and actions have [consequential effects upon] the world around us. - Process Metaphysician Alfred North Whitehead

Kurt Gödel's Incompleteness Theorem says (i) all closed systems are unprovable within themselves and, that (ii) all open systems are rightly understood as incomplete. - R.E. Slater

The most true thing about you is what God has said to you in Christ, "You are My Beloved." - Tripp Fuller

The God among us is the God who refuses to be God without us, so great is God's Love. - Tripp Fuller

According to some Christian outlooks we were made for another world. Perhaps, rather, we were made for this world to recreate, reclaim, redeem, and renew unto God's future aspiration by the power of His Spirit. - R.E. Slater

Our eschatological ethos is to love. To stand with those who are oppressed. To stand against those who are oppressing. It is that simple. Love is our only calling and Christian Hope. - R.E. Slater

Secularization theory has been massively falsified. We don't live in an age of secularity. We live in an age of explosive, pervasive religiosity... an age of religious pluralism. - Peter L. Berger

Exploring the edge of life and faith in a post-everything world. - Todd Littleton

I don't need another reason to believe, your love is all around for me to see. – Anon

Thou art our need; and in giving us more of thyself thou givest us all. - Khalil Gibran, Prayer XXIII

Be careful what you pretend to be. You become what you pretend to be. - Kurt Vonnegut

Religious beliefs, far from being primary, are often shaped and adjusted by our social goals. - Jim Forest

We become who we are by what we believe and can justify. - R.E. Slater

People, even more than things, need to be restored, renewed, revived, reclaimed, and redeemed; never throw out anyone. – Anon

Certainly, God's love has made fools of us all. - R.E. Slater

An apocalyptic Christian faith doesn't wait for Jesus to come, but for Jesus to become in our midst. - R.E. Slater

Christian belief in God begins with the cross and resurrection of Jesus, not with rational apologetics. - Eberhard Jüngel, Jürgen Moltmann

Our knowledge of God is through the 'I-Thou' encounter, not in finding God at the end of a syllogism or argument. There is a grave danger in any Christian treatment of God as an object. The God of Jesus Christ and Scripture is irreducibly subject and never made as an object, a force, a power, or a principle that can be manipulated. - Emil Brunner

“Ehyeh Asher Ehyeh” means "I will be that who I have yet to become." - God (Ex 3.14) or, conversely, “I AM who I AM Becoming.”

Our job is to love others without stopping to inquire whether or not they are worthy. - Thomas Merton

The church is God's world-changing social experiment of bringing unlikes and differents to the Eucharist/Communion table to share life with one another as a new kind of family. When this happens, we show to the world what love, justice, peace, reconciliation, and life together is designed by God to be. The church is God's show-and-tell for the world to see how God wants us to live as a blended, global, polypluralistic family united with one will, by one Lord, and baptized by one Spirit. – Anon

The cross that is planted at the heart of the history of the world cannot be uprooted. - Jacques Ellul

The Unity in whose loving presence the universe unfolds is inside each person as a call to welcome the stranger, protect animals and the earth, respect the dignity of each person, think new thoughts, and help bring about ecological civilizations. - John Cobb & Farhan A. Shah

If you board the wrong train it is of no use running along the corridors of the train in the other direction. - Dietrich Bonhoeffer

God's justice is restorative rather than punitive; His discipline is merciful rather than punishing; His power is made perfect in weakness; and His grace is sufficient for all. – Anon

Our little [biblical] systems have their day; they have their day and cease to be. They are but broken lights of Thee, and Thou, O God art more than they. - Alfred Lord Tennyson

We can’t control God; God is uncontrollable. God can’t control us; God’s love is uncontrolling! - Thomas Jay Oord

Life in perspective but always in process... as we are relational beings in process to one another, so life events are in process in relation to each event... as God is to Self, is to world, is to us... like Father, like sons and daughters, like events... life in process yet always in perspective. - R.E. Slater

To promote societal transition to sustainable ways of living and a global society founded on a shared ethical framework which includes respect and care for the community of life, ecological integrity, universal human rights, respect for diversity, economic justice, democracy, and a culture of peace. - The Earth Charter Mission Statement

Christian humanism is the belief that human freedom, individual conscience, and unencumbered rational inquiry are compatible with the practice of Christianity or even intrinsic in its doctrine. It represents a philosophical union of Christian faith and classical humanist principles. - Scott Postma

It is never wise to have a self-appointed religious institution determine a nation's moral code. The opportunities for moral compromise and failure are high; the moral codes and creeds assuredly racist, discriminatory, or subjectively and religiously defined; and the pronouncement of inhumanitarian political objectives quite predictable. - R.E. Slater

God's love must both center and define the Christian faith and all religious or human faiths seeking human and ecological balance in worlds of subtraction, harm, tragedy, and evil. - R.E. Slater

In Whitehead’s process ontology, we can think of the experiential ground of reality as an eternal pulse whereby what is objectively public in one moment becomes subjectively prehended in the next, and whereby the subject that emerges from its feelings then perishes into public expression as an object (or “superject”) aiming for novelty. There is a rhythm of Being between object and subject, not an ontological division. This rhythm powers the creative growth of the universe from one occasion of experience to the next. This is the Whiteheadian mantra: “The many become one and are increased by one.” - Matthew Segall

Without Love there is no Truth. And True Truth is always Loving. There is no dichotomy between these terms but only seamless integration. This is the premier centering focus of a Processual Theology of Love. - R.E. Slater

-----

Note: Generally I do not respond to commentary. I may read the comments but wish to reserve my time to write (or write from the comments I read). Instead, I'd like to see our community help one another and in the helping encourage and exhort each of us towards Christian love in Christ Jesus our Lord and Savior. - re slater

Monday, December 3, 2018

The Annunciation & Magnificat of Mary



\Gabriel's Announcement to Mary
(The Annunciation)
Luke 1.26-38

"In the sixth month,
the angel Gabriel was sent from God
to a town of Galilee called Nazareth,
to a virgin betrothed to a man named Joseph,
of the house of David,
and the virgin's name was Mary.

And coming to her, he said,
"Hail, full of grace! The Lord is with you."

But she was greatly troubled at what was said
and pondered what sort of greeting this might be.

Then the angel said to her,
"Do not be afraid, Mary,
for you have found favor with God.
Behold, you will conceive in your womb and bear a son,
and you shall name him Jesus.
He will be great and will be called Son of the Most High,
and the Lord God will give him the throne of David his father,
and he will rule over the house of Jacob forever,
and of his Kingdom there will be no end."

But Mary said to the angel,
"How can this be,
since I have no relations with a man?"

And the angel said to her in reply,
"The Holy Spirit will come upon you,
and the power of the Most High will overshadow you.
Therefore the child to be born
will be called holy, the Son of God.

...And behold, Elizabeth, your relative,
has also conceived a son in her old age,
and this is the sixth month for her who was called barren;
for nothing will be impossible for God."

Mary said, "Behold, I am the handmaid of the Lord.
May it be done to me according to your word."

Then the angel departed from her.






The Magnificat of Mary
Luke 1:46-55 King James Version (KJV)

46 And Mary said, My soul doth magnify the Lord,

47 And my spirit hath rejoiced in God my Saviour.

48 For he hath regarded the low estate of his handmaiden: for, behold, from henceforth all generations shall call me blessed.

49 For he that is mighty hath done to me great things; and holy is his name.

50 And his mercy is on them that fear him from generation to generation.

51 He hath shewed strength with his arm; he hath scattered the proud in the imagination of their hearts.

52 He hath put down the mighty from their seats, and exalted them of low degree.

53 He hath filled the hungry with good things; and the rich he hath sent empty away.

54 He hath helped his servant Israel, in remembrance of his mercy;

55 As he spake to our fathers, to Abraham, and to his seed for ever.


Michelangelo's Pietà

Michelangelo's Pietà

Michelangelo's Pietà

Michelangelo's Pietà

* * * * * * * * * *



THE MAGNIFICAT

The Magnificat, taken from Luke’s Gospel (1:46-55), is the Blessed Virgin Mary’s hymn of praise to the Lord. It is also known as the Canticle of Mary in the Liturgy of the Hours, a special collection of scripture readings, psalms, and hymns that constitute what is known as the prayer of the church. (Priests and other religious are required to pray sections from the Liturgy of the Hours each day.)

Although the Magnificat has had numerous musical settings from such composers as Palestrina, Bach and Mozart, it can be recited as well as sung. Its name comes from the first line of its text in Latin (“Magnificat anima mea Dominum”) translated in the first line below. Mary proclaims the Lord’s greatness with characteristic humility and grace here.
My soul magnifies the Lord
And my spirit rejoices in God my Savior;
Because He has regarded the lowliness of His handmaid;
For behold, henceforth all generations shall call me blessed;
Because He who is mighty has done great things for me,
and holy is His name;
And His mercy is from generation to generation
on those who fear Him.
He has shown might with His arm,
He has scattered the proud in the conceit of their heart.
He has put down the mighty from their thrones,
and has exalted the lowly.
He has filled the hungry with good things,
and the rich He has sent away empty.
He has given help to Israel, his servant, mindful of His mercy
Even as he spoke to our fathers, to Abraham and to his posterity forever.
The Magnificat provides great material for meditation on the Visitation, the second Joyful Mystery of the Rosary, pictured above. When the angel Gabriel informs Mary that she is to be the Mother of God, he also tells her of her relative Elizabeth’s pregnancy with John the Baptist.

After Mary gives her famous consent to becoming the Mother of God, -- “Behold the handmaid of the Lord; be it done to me according to thy word” (Luke 1:38) -- she goes “with haste” (1:39) to help Elizabeth, who is delighted to see her. Our Lady then expresses her joy in the Magnificat.

Clearly Mary, in hastening to help her cousin, is focused on service to others. In this way she glorifies the Lord in reflecting (and “magnifying”) His goodness and love. And, of course by becoming the Mother of God she will help Him redeem us for our salvation in His Passion!

Speaking of magnifying, Archbishop Fulton J. Sheen once referred to our Blessed Mother as being like “a magnifying glass that intensifies our love of her Son.”

Note that Mary’s joyful claim that “all generations shall call me blessed” in no way takes away from her humility. If she seems to boast here, it is much as St. Paul does later on in scripture when he says “whoever boasts, should boast in the Lord” (2 Cor 10:17), that is to say, in God’s work being done through us.

In this regard, the Magnificat is more than a prayer of praise. It also reminds us about the essential link between humility and holiness. Just as God has “regarded the lowliness of his handmaid” and “has done great things” for Mary in making her the Mother of his Son, so too “he has put down the mighty from their thrones (with his own might!) and has exalted the lowly.”

(Note also our Blessed Mother’s humility in referring to herself in this prayer, as she does in giving her consent to Gabriel mentioned earlier, as the Lord’s handmaid, his servant!)

As her Divine Son later stressed “Whoever exalts himself shall be humbled, and whoever humbles himself shall be exalted” (Matt 23:12, also in slightly different words in Luke 18:14 and Luke 14:11).

Jesus wasn’t saying anything new here, either! We read similar thoughts throughout the Old Testament such as in the Psalms and in this example from the book of Sirach “Humble yourself the more, the greater you are, and you will find favor with God.” (Sirach 3:19)

The line about God filling “the hungry with good things” resonates later in the Gospels as well, when our Lord says “Blessed are they who hunger and thirst after righteousness for they will be filled” (Matt 5:7). This serves as a good reminder for us to “stay hungry” for God’s graces in praying and in reading His word in scripture.

And as for the rich being sent away empty? This line refers to those who live for wealth and power and feel they have everything figured out. These people in, effect wish to be Gods rather than God’s. How can our Lord fill those who are already full--of themselves?

How about you? Does your soul magnify the Lord? We may never be able to approach Him from Mary’s level of sanctity as the Mother of God. Still, we are all called to be saints nonetheless.

Your good example, like our Blessed Mother’s, can help others in their spiritual growth. Do people see Christ’s love and goodness in you? Are you letting God work within you to accomplish His will? Let Mary help give you the graces you need to follow her Son and His Church in praying the Magnificat.

As St. Ambrose once said in referring to this wonderful prayer, "Let Mary's soul be in us to glorify the Lord; let her spirit be in us that we may rejoice in God our Saviour."

* * * * * * * * * *




Magnificat


The Magnificat (Latin for "[My soul] magnifies [the Lord]") is a canticle, also known as the Song of Mary, the Canticle of Mary and, in the Byzantine tradition, the Ode of the Theotokos (Greek: Ἡ ᾨδὴ τῆς Θεοτόκου). It is traditionally incorporated into the liturgical services of the Catholic Church (at vespers) and of the Eastern Orthodox churches (at the morning services).[1] It is one of the eight most ancient Christian hymns and perhaps the earliest Marian hymn.[2][3] Its name comes from the incipit of the Latin version of the canticle's text.

The text of the canticle is taken directly from the Gospel of Luke (1:46–55) where it is spoken by Mary upon the occasion of her Visitation to her cousin Elizabeth.[2] In the narrative, after Mary greets Elizabeth, who is pregnant with John the Baptist, the latter moves within Elizabeth's womb. Elizabeth praises Mary for her faith (using words partially reflected in the Hail Mary), and Mary responds with what is now known as the Magnificat.

Within the whole of Christianity, the Magnificat is most frequently recited within the Liturgy of the Hours. In Western Christianity, the Magnificat is most often sung or recited during the main evening prayer service: Vespers in the Catholic and Lutheran churches, and Evening Prayer (or Evensong) in Anglicanism. In Eastern Christianity, the Magnificat is usually sung at Sunday Matins. Among Protestant groups, the Magnificat may also be sung during worship services, especially in the Advent season during which these verses are traditionally read.

Context

Mary's Magnificat, recorded only in Luke's Gospel, is one of four hymns, distilled from a collection of early Jewish-Christian canticles, which complement the promise-fulfillment theme of Luke's infancy narrative. These songs are Mary's Magnificat; Zechariah's Benedictus (1:67–79); the angels' Gloria in Excelsis Deo(2:13–14); and Simeon's Nunc dimittis (2:28–32). In form and content, these four canticles are patterned on the "hymns of praise" in Israel's Psalter. In structure, these songs reflect the compositions of pre-Christian contemporary Jewish hymnology. The first stanza displays graphically a characteristic feature of Hebrew poetry—synonymous parallelism—in ascribing praise to God: "my soul" mirrors "my spirit"; "proclaims the greatness" with "has found gladness"; "of the Lord" with "in God my Savior." The balance of the opening two lines bursts out into a dual Magnificat of declaring the greatness of and finding delight in God. The third stanza again demonstrates parallelism, but in this instance, three contrasting parallels: the proud are reversed by the low estate, the mighty by those of low degree, and the rich by the hungry.

Although there is some scholarly discussion of whether the historical Mary herself actually proclaimed this canticle, Luke portrays her as the singer of this song of reversals and the interpreter of the contemporary events taking place. Mary symbolizes both ancient Israel and the Lucan faith-community as the author/singer of the Magnificat.

The canticle echoes several biblical passages, but the most pronounced allusions are to the Song of Hannah, from the Books of Samuel (1 Samuel 2:1–10). Scriptural echoes from the Torah, the Prophets, and the Writings complement the main allusions to Hannah's "magnificat of rejoicing".[4] Along with the Benedictus, as well as several Old Testament canticles, the Magnificat is included in the Book of Odes, an ancient liturgical collection found in some manuscripts of the Septuagint.

Structure

In a style reminiscent of Old Testament poetry and song, Mary praises the Lord in alignment with this structure:

  • Mary rejoices that she has the privilege of giving birth to the promised Messiah (Luke 1:46–48).
  • She glorifies God for His power, holiness, and mercy (Luke 1:49–50).
  • Mary looks forward to God transforming the world through the Messiah. The proud will be brought low, and the humble will be lifted up; the hungry will be fed, and the rich will go without (Luke 1:51–53).
  • Mary exalts God because He has been faithful to His promise to Abraham (Luke 1:54–55; see God’s promise to Abraham in Gen 12:1-3).


* * * * * * * * * *




Behold, the Handmaid of the Lord
- The Annunciation


Today (and on the Fourth Sunday of Advent) the Church reads, as the Gospel of the Mass, St. Luke's description of the point at which time divides.  From this moment, there is time before and time after, whether you call the periods on either side Before Christ (BC) or Before the Common Era (BCE) or Anno Domini (AD) or Common Era (CE), the point is the same -- Christ has come into the world.  With Mary's statement of acceptance "May it be done to me according to your word" we enter a new place, with new possibilities.

There are countless images of the Annunciation throughout history.  Too many, in fact, to write a history of the subject in the brief confines of this blog.  Such a note would go on forever!  So, I have decided to write about only one image, the panel painting by Fra Angelico now in the Prado.  It was painted sometime between 1424 and 1426, possibly for the church of San Lorenzo in Florence, possibly for the Dominican church in Fiesole, where it was historically placed.1



The 1420s were a time when Guido di Pietro (his Baptismal name), known as Fra Giovanni (the name Angelico was given to him posthumously on account of his paintings and life) was still a fairly young painter with a developing style.  At this point he stands on the cusp, as it were, of finding his final style.  This painting represents a point at which his earlier, delicately Gothic style was being influenced by the work of another Florentine painter, Masaccio, toward a slightly more monumental direction.  This painting is an almost perfect example of the early fusion of these two influences.  It is also a beautiful exposition of the implications of the Annunciation.

In this painting we see Mary, seated on a bench draped in fabric which also drapes the wall behind her, forming a kind of cloth of state.  She sits in an open, groin-vaulted loggia, an open prayer book on her knee, and responds gently to the approach of Gabriel, her gesture mirroring his.

Gabriel appears to have just landed, his wings still half open, his knees just beginning to bend.
From the upper left corner of the picture, the hands of God send streams of golden light toward her and, on those beams, the Holy Spirit is seen as a dove descending (just above Gabriel's head).2










Above the column that divides Gabriel and Mary is an image of Jesus, presented as a bust in relief.  So all Persons of the Trinity appear in some way within the picture.

On Mary's side of the space, seated on the iron cross bar between the pillars, is a swallow, symbolic of the Incarnation.
The entire left side of the painting is occupied by a garden filled with highly detailed representations of plant life.  And, in this garden appears the scene from Genesis of Adam and Eve being driven out of the Garden of Eden by an angel.  We see here the tipping point of salvation history.  Mary is being invited to participate in righting the wrong done by Adam and Eve.   Her obedient fiat (Be it done to me) will cancel their disobedience in eating the forbidden fruit. 

The painting represents the moment just before the world begins anew.  Mary's yes will begin it again, with Jesus as the new Adam and Mary herself as the new Eve in a new Garden of Eden of the spirit.

© M. Duffy, 2011

_____________________________________

1. Kanter, Laurence. "Fra Angelico: A Decade of Transition (1422-32)" in Fra Angelico, New York, New Haven and London, The Metropolitan Museum of Art and Yale University Press, 2005, pp. 80-83. This is the catalogue of an exhibition of the work of Fra Angelico held at the Metropolitan Museum of Art in New York, October 26, 2005 - January 29, 2006. 

2. Ferguson, George. Signs and Symbols in Christian Art, New York, Oxford University Press, 1966, pp. 25-26.

Posted by Margaret Duffy










Saturday, December 1, 2018

What Attracts Me to Process Theology - by R.E. Slater



What attracts me as a Christian to process theology? Mainly its expansiveness to include others of different faiths, religions, races, cultures, and beliefs behind its central tenants of love, unity, peace, goodwill, social and environmental justice, and so on. It is a binder, a healer, a way to envision a better future.


What this does not mean is that Christianity as a faith loses its historical character of God-ness, Jesus, or Holy Spirit filling. But what it does mean is that Christianity loses its un-Godness, un-Christlike-ness, and paucity for Holy Spirit imagination, transformation, and reformation.

Process is also eclectic. It does not need to take from any one direction, system, theology, or philosophy to be itself. It takes each of those streams of tradition and enhances them, binds them to humanity and creation, updates them into current contemporary thought, science, discovery, and work. It is a binder. A unifier. It frees traditional thinking to look past their meager, darker borderlands to broader vistas. To imagine the Word of God as a multi-hued prism or spectral array which would permit Eastern, Continental, Western, and Near-Eastern traditions to consider, "What if."


So here's the scary part for strict traditionalists - they may have to relax their boundaries. Scary indeed. But what if those boundaries came down because of love and understanding for where another is coming from when viewing the worlds of oppression those views were forced to free themselves from? What if, rather than labeling, we say, "Oh, my tradition has given me the wrong impression of what people were struggling for? Or, the reigns of abuse they needed to be freed from?" This is the more valid approach rather than relenting to a criticising, excluding faith position more willing to judge and ostracize others than help.


The Christian faith is a magnanimous faith - not a reproaching faith. Jesus taught God in many languages, vernaculars, and within hostile environments. Why should the Christian faith be any different unless it is not true and has something to lose? Unless all it believes cannot be bigger than itself in honor to the Father-Creator of all? Unless it prefers sticking to its own slogans, beliefs, and exclusions? If God is God than God is other than exclusion which the Christian tradition has created through its denominational crusades and holy wars of jihad upon the world. It should expand Jesus to the world rather than delimit Him to a few pulpiteers speaking lies in clever eloquence, oratory power, and selective beliefs.


As such, over the past 90 years since Alfred North Whitehead’s seminal publication, "Process and Reality," North's relational, open, organic worldview has taken shape in a myriad of unique ways. It has been said that Process Theology is one of the most important movements in 21st Century American liberal theology, in connection with liberation theology, feminist theology, eco-theology, religious pluralism, religion and science, panpsychism, panentheism, postmodern, and the list goes on.

Christian based Process theology can touch each one of these modern trajectories and can both bring and find enlightenment to its rich church legacies if it is willing to try. If not, the barriers still remain high, the gospel delimited by its professors, and God's salvific healing to the world in Christ remains meaningless to a world designed to be organic, holistic, complexly networked, and redemptive.


Finally, process theology is not strictly a Christian, Western, or Continental phenomena. There are religious followers from around the globe who find aspects of process thought illuminating for their own respective traditions. Muslim, Jewish, Hindu, and other thinkers have infused their religiosity with process relational thinking in extremely fruitful ways. But where do we go from here? What will the future of process theology look like? These are the key questions from which only a post-modern society may answer as it slips backwards into post-truth nationalism, patriotism, and divisive labeling for gain, power, notoriety, and infamy. For once, in contemporary theology, there is a definitive solution which is broad enough to transport the Christian faith into all areas of life and not just a secular, religious, denoministic view of life. It may transform itself into a sepulcher of holiness permeated with love, healing, real hope, and Spirit-filled transformation.

R.E. Slater
December 1, 2018



Friday, August 17, 2018

Recommended Reading: Mayra Rivera's "Poetics of the Flesh"


Recommended: "Poetics of the Flesh:" I have contended for sometime - commencing with my biblical education in undergraduate studies at a bible university - that "flesh" (sarx) and "body" (soma) are intricately intra-connected between the "law of God" and the "law of sin" with no ability to separate the two concepts so simply as many theologies have implied. Here, in Mayra Rivera's review, she does the same while moving the discussion into a postmodern context of inter-relateability of the human soul as it develops through childhood's naive position of "self" to its maturing "mirrored" reflection of "self in the eyes of others," however rightly or wrongly obtained from the words and reactions of others. Others who may bear the best of intentions or the worst of intentions as forebearers of either "life" or "death" to the souls they speak to. All the while this discussion flows between a redefining of how the ancient Greek concepts of flesh and body contemporarily interacts with the wholeness of our being, persona, social relations, and the world itself, including the Creator of this world we live and breathe. In the echoing reflections of NT Wright one might hear the words of "Well done" to Mayra's reconceptions of blending a Greek culture's binary concepts of the world into a unifying whole so emphasized by the earlier Jewish/Semetic custom of "oneness" to the "duality of life" expressed in more blatant Western contexts. As such, to those requiring a new, more maturer, outlook upon the old theologies we have grown up with I would recommend this study.

R.E. Slater
August 17, 2018

OLD 20TH CENTURY CHRISTIAN ILLUSTRATIONS
OF "BODY-SOUL-SPIRIT"

Old Bible Illustration of the Parts of Man,
by Dispensational Theologican Clarence Larkin

Old Bible Illustration of the Parts of Man,
by Dispensational Theologican Clarence Larkin

Old Bible Illustration of the Parts of Man,
by the 20th Century Church

Old Bible Illustration of the Parts of Man,
by the 20th Century Church



BOOK BLURB

In "Poetics of the Flesh "Mayra Rivera offers poetic reflections on how we understand our carnal relationship to the world, at once spiritual, organic, and social. She connects conversations about corporeality in theology, political theory, and continental philosophy to show the relationship between the ways ancient Christian thinkers and modern Western philosophers conceive of the "body" and "flesh.” Her readings of the biblical writings of John and Paul as well as the work of Tertullian illustrate how Christian ideas of flesh influenced the works of Maurice Merleau-Ponty and Michel Foucault, and inform her readings of Judith Butler, Frantz Fanon, and others. Rivera also furthers developments in new materialism by exploring the intersections among bodies, material elements, social arrangements, and discourses through body and flesh. By painting a complex picture of bodies, and by developing an account of how the social materializes in flesh, Rivera provides a new way to understand gender and race.


Amazon link




Review of Poetics of the Flesh
by "Reading Religion,"
Publication of AAR (American Academy of Religion) 

Title: Poetics of the Fles
Author: Mayra Rivera
Publication Date: October 2015
Publisher: Duke University Press, Durham, NC, USA
216 pages.
Paperback.
ISBN - 9780822360131
For other formats: Link to Publisher's Website.


Reading Religion Review

Mayra Rivera guides readers of Poetics of the Flesh on a journey through the rich and diverse understandings of flesh and body in the Western Christian tradition. The monograph is divided into three parts: Part I, “Regarding Christian Bodies,” examines the concepts of “flesh” (sarx) and “body” (soma) in John’s Gospel, Paul’s letters, and Tertullian’s writings; Part II, “The Philosophers’ (Christian) Flesh,” “focuses on flesh as dynamic relation between the body and the world” (58) through the writings of Maurice Merleau-Ponty and critiques by Michel Foucault, Jean-Luc Nancy, and Luce Irigaray; Part III, “A Labyrinth of Incarnations,” analyzes the particular ways in which flesh is shaped by the world, interlaced with social identities and social perceptions of bodies (114). Many voices join the discussion here, with primary attention given to Frantz Fanon, Aimé Césaire, and Judith Butler. Although it is a challenging read, this book constructively advances theological anthropology and material discourses by creatively (re)making (poiesis) words that become flesh.

As Rivera explains, “Poetics of the Flesh is inspired by the practice of Édouard Glissant’s Poetics of Relation” (2). Rivera cites Derek Walcott’s description of Glissant’s poetics, which is analogously compared to lovingly gathering and reassembling the pieces of a broken vase. Rivera approaches the texts, which range from Greek scriptures to continental phenomenology to Caribbean poetry, “as part of ongoing, sometimes painful processes of remaking visions of corporeality—out of pieces of shattered histories and shards of vocabulary” (4). Indeed, this analogy of carefully and creatively (re)constructing a theology of flesh well describes Rivera’s text. She begins this process by problemetizing, with Sharon Betcher, the recent theological turn to the body which sometimes “represents the unattainable stability that social norms demand but that corporeality cannot mirror” (7). Poetics of the Flesh offers a theological response to Betcher’s call to “learn to think flesh without ‘the body’” (7).

While some readers (including myself, I confess) may be initially frustrated by Rivera’s refusal to clearly distinguish between “flesh” and “body” in her introductory chapter, it gradually becomes evident that doing so would undermine the project as a whole. “Words do not simply mirror what is, or express the thoughts and desires of a person, but rather shape reality and subjectivity. . . . We are interested in processes of materialization—not just in matter” (9). Re-reading the introduction, having read the body of Rivera’s text, I now recognize that any facile attempt at the outset to define the words “body” and “flesh” would obscure not only their complex genealogies but also the subtleties of becoming flesh that are (in some ways) continued and (in other ways) initiated by Rivera’s poetic processes of materialization in which the reader becomes ever more intertwined and interlaced.

Chapter 1, as one might expect, examines the term “flesh” in John’s Gospel. Far from a philological analysis of sarx, however, Rivera’s thematic trek through the Fourth Gospel incorporates interpretations by Karmen MacKendrick, Tat-siong Benny Liew, and others. Most notably, she draws upon liberationist readings of Bartolomé de las Casas and the “elemental materiality [that] connects the bodies of workers with shared bread, with consecrated bread” (23). The gospel, Rivera asserts, resists attempts to literally or figuratively separate word, flesh, spirit, and bread—all the while interlacing boundaries between individual and societal bodies.

Distinctions between flesh (sarx) and body (soma) are simultaneously sharpened and blurred through Rivera’s examination of the Pauline Epistles (chapter 2). For Paul, metaphysically transcendent spiritual bodies enslaved to the “law of God” stand in contrast to flesh enslaved to the “law of sin” (36, citing Romans 7:25). In chapter 3, Rivera traces “the affirmative images of flesh [in Tertullian’s writings], as they unfold from the poetics of the Gospel of John and the letters of Paul” (44). Here, the logic of poetics operates on two levels: within Tertullian’s corpus and in Rivera’s revitalization thereof. Without excusing or condemning Tertullian’s gendered hierarchies, Rivera demonstrates that the gender rift undermines his argument: “unless you can embrace your own flesh, and its beginnings in the flesh of another, you cannot love other fleshly beings—nor can you understand the incarnation” (53).

While the intricacies of Part II can hardly be summarized in this brief review, one moment strikes me as an especially poignant passage from the heart of the text. In a section entitled “intercorporeal engagements,” Rivera highlights Merleau-Ponty’s analysis of child psychology. In the developmental transition from subjective indistinction to individuality (a process which Merleau-Ponty insists “is never completely finished” (68)), a child enters the “mirror stage.” “In recognizing her image in the mirror,” explains Rivera, “the child learns that there can be a viewpoint taken on her. The child notices that she is visible, to herself and to others” (69). “[M]y experience of my body,” she continues, “is always already entwined with images that others have of me. . . . I borrow myself from others” (70).

Personally, I only truly began to grasp Rivera’s constructive theology of flesh at this point in the text. Unless I am misreading and perhaps making too much of but one passage, I would have preferred some foreshadowing of this moment—which is woven through later portions of the text—in the introduction. Rivera performs an apophatic phenomenology of multiplication (contra negation) through which touching flesh intertwines as a desire for the “you in me and the me in you” (77, John 14:20). This interlacing of inner and social identities informs Rivera’s reading of Frantz Fanon’s critique of Merleau-Ponty and—even more rewardingly—Fanon’s reading of fellow Martinican Aimé Césaire. Rivera, who later offers a critique of Simone de Beauvoir, notes that these authors become black and become gendered as “effects of the white gaze” (129).

Mayra Rivera’s Poetics of the Flesh is (for me, at least) a challenging text that is well worth the effort and attention it demands of its reader. The difficulty it poses is due to the richly profound space it opens for a carnal theology in which the reader is always already entangled and involved. The monograph might be faulted for omitting any engagement (critical or otherwise) with the writings of Jean-Luc Marion, which also explore Merleau-Ponty’s sensual phenomenology of flesh from a postmodern theological perspective. Nevertheless, Rivera’s text makes significant and noteworthy advancement, not only in theological anthropology, critical theory, and materiality, but also in an apophatic theology grounded in the immanent indeterminacy of multiplicity and relational, worldly ontology. While the book is unlikely to find its way onto undergraduate syllabi, it can be considered an enjoyable “must read” for many theologians, philosophers, and advanced graduate students.

About the Reviewer
Brad Bannon is an adjunct professor of theology at Fitchburg State University.
Date of Review: May 30, 2016

About the Author
Mayra Rivera is Associate Professor of Theology and Latina/o Studies at Harvard University and the author of The Touch of Transcendence: A Postcolonial Theology of God.







Wednesday, August 15, 2018

The Amazing Story of Oxygen


I noticed I had not talked about the story of oxygen. I have mentioned it in several articles over the years but not explicitly. In a nutshell, oxygen was a toxic gas in primordial earth's early history until it was not. How and why did this happen? It begins with the story of methane gas. Further, it seems to explain quite sufficiently the explosion of life in the Cambrian Period which everyone seems to make a fuss over (Why All the Fuss over Earth's Remarkable Cambrian Explosion?). So to help develop this line of thought I wish to briefly begin this discussion with no further commentary. I leave it to the reader to develop its language. I also wish to tag it to my most recent article written earlier today (Choosing Life And The Responsibilities of Good Earth Caretake Which Go With It).

R.E. Slater
August 15, 2018
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Photo of earth filled with thick, methane-rich haze

 https://www.dailymail.co.uk/sciencetech/article-4310772/Earth-s-atmosphere-toxic-fog-methane.html

A period more than 2.4 billion years ago, when
Earth’s atmosphere was filled with a thick, methane-rich haze
much like Saturn’s moon Titan.


Methane-filled Atmosphere of Early Earth
Helped ‘Clear the Air’ for Oxygen

March 13, 2017
Contacts: Matthew Wright, 301-405-9267

COLLEGE PARK, Md. -- More than 2.4 billion years ago, Earth’s atmosphere was inhospitable, filled with toxic gases that drove wildly fluctuating surface temperatures. New research from the University of Maryland, the University of St. Andrews, NASA’s Jet Propulsion Laboratory, the University of Leeds and the Blue Marble Space Institute of Science suggests that a million-year-long methane haze helped clear the way for today’s world of mild climates and breathable air.

The team’s new research indicates that this methane-rich haze drove a large amount of hydrogen out of the atmosphere, making room for massive amounts of oxygen. Their work, published March 13, 2017 in the early online edition of the Proceedings of the National Academy of Sciences, thus proposes a new contributing cause for the “Great Oxidation Event,” which occurred 2.4 billion years ago. During this event, oxygen concentrations in Earth’s atmosphere increased more than 10,000 times, resulting in an atmosphere much like the one that sustains life on Earth today. 

“The transformation of Earth’s air from a toxic mix to a more welcoming, oxygen-rich atmosphere happened in a geological instant,” said James Farquhar, a professor of geology at UMD and a co-author of the study. Farquhar also has an appointment at UMD’s Earth System Science Interdisciplinary Center. “With this study, we finally have the first complete picture of how methane haze made this happen.”

The researchers used detailed chemical records and sophisticated atmospheric models to reconstruct atmospheric chemistry during the time period immediately before the Great Oxidation Event. Their results suggest that ancient bacteria—the only life on Earth at the time—produced massive amounts of methane that reacted to fill the air with a thick haze, resembling the modern-day atmosphere of Saturn’s moon Titan. 

Previous studies by many of the same researchers had identified several such haze events early in Earth’s history. But the current study is the first to show how rapidly these events began and how long they lasted.

“High methane levels meant that more hydrogen, the main gas preventing the build up of oxygen, could escape into outer space, paving the way for global oxygenation,” said Aubrey Zerkle, a biogeochemist at the University of St. Andrews and a co-author of the study. “Our new dataset constitutes the highest resolution record of Archean atmospheric chemistry ever produced, and paints a dramatic picture of Earth surface conditions before the oxygenation of our planet.”

The methane haze persisted for about a million years. After enough hydrogen left the atmosphere, the right chemical conditions took over and the oxygen boom got underway, enabling the evolution of all multicellular life. 

The key to the researchers’ analysis was the discovery of anomalous patterns of sulfur isotopes in the geochemical records from this time. Sulfur isotopes are often used as a proxy to reconstruct ancient atmospheric conditions, but previous investigations into the time period in question had not revealed anything too unusual.

“Reconstructing the evolution of atmospheric chemistry has long been the focus of geochemical research,” said Gareth Izon, lead author of the study, who contributed to the research while a postdoctoral researcher at St. Andrews and is now a postdoctoral researcher at the Massachusetts Institute of Technology. “Our new data show that the chemical composition of the atmosphere was dynamic and, at least in the prelude to the Great Oxidation Event, hypersensitive to biological regulation.” 

This release is based on text provided by the University of St. Andrews.

The research paper, “Biological regulation of atmospheric chemistry en route to planetary oxygenation,” Gareth Izon, Aubrey Zerkle, Kenneth Williford, James Farquar, Simon Poulton, and Mark Claire, was published March 13, 2017 in the Proceedings of the National Academy of Sciences.

This work was supported by the Natural Environment Research Council (Award Nos. NE/H016805 and NE/J023485), the Scottish Alliance for Geoscience, Environment and Society, The Geological Society of London’s Alan and Charlotte Welch Fund, NASA (Award No. NNX12AD91G), The Royal Society, and the European Research Council (Award No. 678812). The content of this article does not necessarily reflect the views of these organizations.


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Evolution Of The Atmosphere:
Composition, Structure And Energy


I inhale great draughts of space,
The east and west are mine, and the north and the south are mine
I am larger, better than I thought,
I did not know I held so much goodness - all seems beautiful to me.

- Song of the Open Road, Walt Whitman


Driving Questions:
  • How did the atmosphere evolve into what it is today?
  • What gases in the atmosphere are important to life and how are they maintained?
  • What natural variations occur in atmospheric constituents and what are the important time scales for change?

1. The Earliest Atmosphere, Oceans, and Continents

After loss of the hydrogen, helium and other hydrogen-containing gases from early Earth due to the Sun's radiation, primitive Earth was devoid of an atmosphere. The first atmosphere was formed by outgassing of gases trapped in the interior of the early Earth, which still goes on today in volcanoes. 

For the Early Earth, extreme volcanism occurred during differentiation, when massive heating and fluid-like motion in the mantle occurred. It is likely that the bulk of the atmosphere was derived from degassing early in the Earth's history. The gases emitted by volcanoes today are in Table 1 and in Figure.

 
Composition of volcanic gases for three volcanoes


Volcanic outgassing

Oxygen in the Atmosphere

    Stromatolite and Banded-iron Formation (BIF)

Life started to have a major impact on the environment once photosynthetic organisms evolved. These organisms, blue-green algae (picture of stromatolite, which is the rock formed by these algae), fed off atmospheric carbon dioxide and converted much of it into marine sediments consisting of the shells of sea creatures.

While photosynthetic life reduced the carbon dioxide content of the atmosphere, it also started to produce oxygen. For a long time, the oxygen produced did not build up in the atmosphere, since it was taken up by rocks, as recorded in Banded Iron Formations (BIFs; picture) and continental red beds. To this day, the majority of oxygen produced over time is locked up in the ancient "banded rock" and "red bed" formations. It was not until probably only 1 billion years ago that the reservoirs of oxidizable rock became saturated and the free oxygen stayed in the air.

The oxidation of the the mantle rocks may have played an important role in the rise of oxygen. It has been hypothesized the the change from predominantly submarine to subaerial volcanoes may have also led to a reduction in volcanic emission of reduced gases.

Once oxygen had been produced, ultraviolet light split the molecules, producing the ozone UV shield as a by-product. Only at this point did life move out of the oceans and respiration evolved. We will discuss these issues in greater detail later on in this course. 

Early Oceans

The Early atmosphere was probably dominated at first by water vapor, which, as the temperature dropped, would rain out and form the oceans. This would have been a deluge of truly global proportions an resulted in further reduction of CO2. Then the atmosphere was dominated by nitrogen, but there was certainly no oxygen in the early atmosphere. The dominance of Banded-Iron Formations (BIFs; see picture) before 2.5Ga indicates that Fe occurred in its reduced state (Fe2+). Whereas reduced Fe is much more soluble than oxidized Fe (Fe3+), it rapidly oxidizes during transport. However, the dissolved O in early oceans reacted with Fe to form Fe-oxide in BIFs. As soon as sufficient O entered the atmosphere, Fe takes the oxidized state and is no longer soluble. The first occurrence of redbeds, a sediments that contains oxidized iron, marks this major transition in Earth's atmosphere.

Cumulative history of O2 by photosynthesis over
geologic time. The start of free O is likely earlier
than shown.

Early Continents

Lava flowing from the partially molten interior spread over the surface and solidified to form a thin crust. This crust would have melted and solidified repeatedly, with the lighter compounds moving to the surface. This is called differentiation. Weathering by rainfall broke up and altered the rocks. The end result of these processes was a continental land mass, which would have grown over time. The most popular theory limits the growth of continents to the first two billion years of the Earth. 

2. Evolution of the Present Atmosphere

The evolution of the atmosphere could be divided into four separate stages:
  • Origin
  • Chemical/ pre-biological era
  • Microbial era, and
  • Biological era.
and the first three steps were discussed in detail. The composition of the present atmosphere however required the formation of oxygen to sufficient levels to sustain life, and required life to create the sufficient levels of oxygen. This era of evolution of the atmosphere is called the "Biological Era."
The Biological Era - The Formation of Atmospheric Oxygen

The biological era was marked by the simultaneous decrease in atmospheric carbon dioxide (CO2) and the increase in oxygen (O2) due to life processes. We need to understand how photosynthesis could have led to maintenance of the ~20% present-day level of O2. The build up of oxygen had three major consequences that we should note here.

Firstly, Eukaryotic metabolism could only have begun once the level of oxygen had built up to about 0.2%, or ~1% of its present abundance. This must have occurred by ~2 billion years ago, according to the fossil record. Thus, the eukaryotes came about as a consequence of the long, steady, but less efficient earlier photosynthesis carried out by Prokaryotes.

Oxygen through photolysis
Figure 1. Photolysis of water vapor and carbon dioxide produce hydroxyl and atomic oxygen, respectively, that, in turn, produce oxygen in small concentrations. This process produced oxygen for the early atmosphere before photosynthesis became dominant.

Oxygen increased in stages, first through photolysis (Figure 1) of water vapor and carbon dioxide by ultraviolet energy and, possibly, lightning:

H2O -> H + OH

produces a hydroxyl radiacal (OH) and

CO2 -> CO+ O

produces an atomic oxygen (O). The OH is very reactive and combines with the O

O + OH -> O2 + H

The hydrogen atoms formed in these reactions are light and some small fraction excape to space allowing the O2 to build to a very low concentration, probably yielded only about 1% of the oxygen available today.

Secondly, once sufficient oxygen had accumulated in the stratosphere, it was acted on by sunlight to form ozone, which allowed colonization of the land. The first evidence for vascular plant colonization of the land dates back to ~400 million years ago.

Thirdly, the availability of oxygen enabled a diversification of metabolic pathways, leading to a great increase in efficiency. The bulk of the oxygen formed once life began on the planet, principally through the process of photosynthesis:

6CO2 + 6H2O <--> C6H12O6 + 6O2

where carbon dioxide and water vapor, in the presence of light, produce organics and oxygen. The reaction can go either way as in the case of respiration or decay the organic matter takes up oxygen to form carbon dioxide and water vapor.

Life started to have a major impact on the environment once photosynthetic organisms evolved. These organisms fed off atmospheric carbon dioxide and converted much of it into marine sediments consisting of the innumerable shells and decomposed remnants of sea creatures.

Cumulative history of O2 by photosynthesis
through geologic time.

While photosynthetic life reduced the carbon dioxide content of the atmosphere, it also started to produce oxygen. The oxygen did not build up in the atmosphere for a long time, since it was absorbed by rocks that could be easily oxidized (rusted). To this day, most of the oxygen produced over time is locked up in the ancient "banded rock" and "red bed" rock formations found in ancient sedimentary rock. It was not until ~1 billion years ago that the reservoirs of oxidizable rock became saturated and the free oxygen stayed in the air. The figure illustrates a possible scenario.

We have briefly mentioned the difference between reducing (electron-rich) and oxidizing (electron hungry) substances. Oxygen is the most important example of the latter type of substance that led to the term oxidation for the process of transferring electrons from reducing to oxidizing materials. This consideration is important for our discussion of atmospheric evolution, since the oxygen produced by early photosynthesis must have readily combined with any available reducing substance. It did not have far to look!

We have been able to outline the steps in the long drawn out process of producing present-day levels of oxygen in the atmosphere. We refer here to the geological evidence.

Banded Iron Formations

When the oceans first formed, the waters must have dissolved enormous quantities of reducing iron ions, such as Fe2+. These ferrous ions were the consequences of millions of years of rock weathering in an anaerobic (oxygen-free) environment. The first oxygen produced in the oceans by the early prokaryotic cells would have quickly been taken up in oxidizing reactions with dissolved iron. This oceanic oxidization reaction produces Ferric oxide Fe2O3 that would have deposited in ocean floor sediments. The earliest evidence of this process dates back to the Banded Iron Formations, which reach a peak occurrence in metamorphosed sedimentary rock at least 3.5 billion years old. Most of the major economic deposits of iron ore are from Banded Iron formations. These formations, were created as sediments in ancient oceans and are found in rocks in the range 2 - 3.5 billion years old. Very few banded iron formations have been found with more recent dates, suggesting that the continued production of oxygen had finally exhausted the capability of the dissolved iron ions reservoir. At this point another process started to take up the available oxygen.

Red Beds

Once the ocean reservoir had been exhausted, the newly created oxygen found another large reservoir - reduced minerals available on the barren land. Oxidization of reduced minerals, such as pyrite FeS2, exposed on land would transfer oxidized substances to rivers and out to the oceans via river flow. Deposits of Fe2O3 that are found in alternating layers with other sediments of land origin are known as Red Beds, and are found to date from 2.0 billion years ago. The earliest occurrence of red beds is roughly simultaneous with the disappearance of the banded iron formation, further evidence that the oceans were cleared of reduced metals before O2 began to diffuse into the atmosphere.

Finally after another 1.5 billion years or so, the red bed reservoir became exhausted too (although it is continually being regenerated through weathering) and oxygen finally started to accumulate in the atmosphere itself. This signal event initiated eukaryotic cell development, land colonization, and species diversification. Perhaps this period rivals differentiation as the most important event in Earth history.

The oxygen built up to today's value only after the colonization of land by green plants, leading to efficient and ubiquitous photosynthesis. The current level of 20% seems stable.

The Oxygen Concentration Problem.

Why does present-day oxygen sit at 20%? This is not a trivial question since significantly lower or higher levels would be damaging to life. If we had < 15% oxygen, fires would not burn, yet at > 25% oxygen, even wet organic matter would burn freely.

The Early Ultraviolet Problem

The genetic materials of cells (DNA) is highly susceptible to damage by ultraviolet light at wavelengths near 0.25 µm. It is estimated that typical contemporary microorganisms would be killed in a matter of seconds if exposed to the full intensity of solar radiation at these wavelength. Today, of course, such organisms are protected by the atmospheric ozone layer that effectively absorbs light at these short wavelengths, but what happened in the early Earth prior to the significant production of atmospheric oxygen? There is no problem for the original non-photosynthetic microorganisms that could quite happily have lived in the deep ocean and in muds, well hidden from sunlight. But for the early photosynthetic prokaryotes, it must have been a matter of life and death.

It is a classical "chicken and egg" problem. In order to become photosynthetic, early microorganisms must have had access to sunlight, yet they must have also had protection against the UV radiation. The oceans only provide limited protection. Since water does not absorb very strongly in the ultraviolet a depth of several tens of meters is needed for full UV protection. Perhaps the organisms used a protective layer of the dead bodies of their brethren. Perhaps this is the origin of the stromatolites - algal mats that would have provided adequate protection for those organisms buried a few millimeters in. Perhaps the early organisms had a protective UV-absorbing case made up of disposable DNA - there is some intriguing evidence of unused modern elaborate repair mechanisms that allow certain cells to repair moderate UV damage to their DNA. However it was accomplished, we know that natural selection worked in favor of the photosynthetic microorganisms, leading to further diversification.

Fluctuations in Oxygen

The history of macroscopic life on Earth is divided into three great eras: the Paleozoic, Mesozoic and Cenozoic. Each era is then divided into periods. The latter half of the Paleozoic era, includes the Devonian period, which ended about 360 million years ago, the Carboniferous period, which ended about 280 million years ago, and the Permian period, which ended about 250 million years ago.

According to recently developed geochemical models, oxygen levels are believed to have climbed to a maximum of 35 percent and then dropped to a low of 15 percent during a 120-million-year period that ended in a mass extinction at the end of the Permian. Such a jump in oxygen would have had dramatic biological consequences by enhancing diffusion-dependent processes such as respiration, allowing insects such as dragonflies, centipedes, scorpions and spiders to grow to very large sizes. Fossil records indicate, for example, that one species of dragonfly had a wing span of 2 1/2 feet.

Geochemical models indicate that near the close of the Paleozoic era, during the Permian period, global atmospheric oxygen levels dropped to about 15 percent, lower that the current atmospheric level of 21 percent. The Permian period is marked by one of the greatest extinctions of both land and aquatic animals, including the giant dragonflies. But it is not believed that the drop in oxygen played a significant role in causing the extinction. Some creatures that became specially adapted to living in an oxygen-rich environment, such as the large flying insects and other giant arthropods, however, may have been unable to survive when the oxygen atmosphere underwent dramatic change. 

3. Composition of the Present Atmosphere

Comparison to Other Planets

The overall composition of the earth's atmosphere is summarized below along with a comparison to the atmospheres on Venus and Mars - our closest neighbors.


The variations in concentration from the Earth to Mars and Venus result from the different processes that influenced the development of each atmosphere. While Venus is too warm and Mars is too cold for liquid water the Earth is at just such a distance from the Sun that water was able to form in all three phases, gaseous, liquid and solid. Through condensation the water vapor in our atmosphere was removed over time to form the oceans. Additionally, because carbon dioxide is slightly soluble in water it too was removed slowly from the atmosphere leaving the relatively scarce but unreactive nitrogen to build up to the 78% is holds today.

Current Composition

The concentrations of gases in the earth atmosphere is now known to be (ignoring water vapor, which varies between near zero to a few percent):


The unit of percentage listed here are for comparison sake. For most atmospheric studies the concentration is expressed as parts per million (by volume). That is, in a million units of air how may units would be that species. Carbon dioxide has a concentration of about 350 ppm in the atmosphere (i.e. 0.000350 of the atmosphere or 0.0350 percent).

Greenhouse Gases


Radiative Properties

Objects that absorb all radiation incident upon them are called "blackbody" absorbers. The earth is close to being a black body absorber. Gases, on the other hand, are selective in their absorption characteristics. While many gases do not absorb radiation at all some selectively absorb only at certain wavelengths. Those gases that are "selective absorbers" of solar energy are the gases we know as "Greenhouse Gases."

The interactive activity to the right allows you to visualize how each greenhouse gas selectively absorbs radiation. Wien's Law states that the wavelength of maximum emission of radiation is inversely proportional to the object's temperature. Using that law we know that the wavelength of maximum emission for the Sun is about 0.5 µm (1 µm = 10-6 m) and the wavelength for maximum emission by the Earth is about 10 µm. In the activity to the right see where the greenhouse gases absorb relative to those two important wavelengths.

Sources and Sinks

Greenhouse Gases (apart from water vapor) include:
and each have different sources (emission mechanisms) and sinks (removal mechanisms) as outlined below.

Carbon Dioxide
  • Sources Released by the combustion of fossil fuels (oil, coal, and natural gas), flaring of natural gas, changes in land use (deforestation, burning and clearing land for agricultural purposes), and manufacturing of cement
  • Sinks Photosynthesis and deposition to the ocean.
  • Importance Accounts for about half of all warming potential caused by human activity.

Methane
  • Sources Landfills, wetlands and bogs, domestic livestock, coal mining, wet rice growing, natural gas pipeline leaks, biomass burning, and termites.
  • Sinks Chemical reactions in the atmosphere.
  • Importance Molecule for molecule, methane traps heat 20-30 times more efficiently than CO2. Within 50 years it could become the most significant greenhouse gas.

Nitrous Oxide
  • Sources Burning of coal and wood, as well as soil microbes' digestion.
  • Sinks Chemical reactions in the atmosphere.
  • Importance Long-lasting gas that eventually reaches the stratosphere where it participates in ozone destruction.

Ozone
  • Sources Not emitted directly, ozone is formed in the atmosphere through photochemical reactions involving nitrogen oxides and hydrocarbons in the presence of sunlight.
  • Sinks Deposition to the surface, chemical reactions in the atmosphere.
  • Importance In the troposphere ozone is a pollutant. In the stratosphere it absorbs hazardous ultraviolet radiation.

Chlorofluorocarbons (CFCs)
  • Sources Used for many years in refrigerators, automobile air conditioners, solvents, aerosol propellants and insulation.
  • Sinks Degradation occurs in the upper atmosphere at the expenses of the ozone layer. One CFC molecule can initiate the destruction of as many as 100,000 ozone molecules.
  • Importance The most powerful of greenhouse gases — in the atmosphere one molecule of CFC has about 20,000 times the heat trapping power on a molecule of CO2.

4. Summary

We developed a few useful tools for the study of biogeochemical cycles. These include the concepts of the reservoir, fluxes, and equilibria.

Atmospheric evolution progressed in four stages, leading to the current situation. The atmosphere has not always been as it is today - and it will change again in the future. It is closely controlled by life and, in turn, controls life processes. Complex feedback mechanisms are at play that we do not yet understand. 

Oxygen became a key atmospheric constituent due entirely to life processes. It built up slowly over time, first oxidizing materials in the oceans and then on land. The current level (20%) is maintained by processes not yet understood. 

Sometime just before the Cambrian, atmospheric oxygen reached levels close enough to today's to allow for the rapid evolution of the higher life forms. For the rest of geologic time, the oxygen in the atmosphere has been maintained by the photosynthesis of the green plants of the world, much of it by green algae in the surface waters of the ocean.

Selective absorbers in our atmosphere keep the surface of the earth warmer than they would be without an atmosphere.


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