scholarly journals Stratospheric Ozone Depletion: An Unlikely Driver of the Regional Trends in Antarctic Sea Ice in Austral Fall in the Late Twentieth Century

2017 ◽  
Vol 44 (21) ◽  
Author(s):  
Laura L. Landrum ◽  
Marika M. Holland ◽  
Marilyn N. Raphael ◽  
Lorenzo M. Polvani
Keyword(s):  
Twentieth Century ◽  
Sea Ice ◽  
Ozone Depletion ◽  
Stratospheric Ozone ◽  
Stratospheric Ozone Depletion ◽  
Antarctic Sea Ice ◽  
Regional Trends ◽  
Late Twentieth ◽  
Late Twentieth Century

scholarly journals Impacts of Interactive Stratospheric Chemistry on Antarctic and Southern Ocean Climate Change in the Goddard Earth Observing System, Version 5 (GEOS-5)

2016 ◽  
Vol 29 (9) ◽  
pp. 3199-3218 ◽  
Author(s):  
Feng Li ◽  
Yury V. Vikhliaev ◽  
Paul A. Newman ◽  
Steven Pawson ◽  
Judith Perlwitz ◽  
...  
Keyword(s):  
Climate Change ◽  
Southern Ocean ◽  
Sea Ice ◽  
Ozone Depletion ◽  
Stratospheric Ozone ◽  
Meridional Overturning Circulation ◽  
Stratospheric Chemistry ◽  
Earth Observing System ◽  
Antarctic Sea Ice ◽  
The Antarctic

Abstract Stratospheric ozone depletion plays a major role in driving climate change in the Southern Hemisphere. To date, many climate models prescribe the stratospheric ozone layer’s evolution using monthly and zonally averaged ozone fields. However, the prescribed ozone underestimates Antarctic ozone depletion and lacks zonal asymmetries. This study investigates the impact of using interactive stratospheric chemistry instead of prescribed ozone on climate change simulations of the Antarctic and Southern Ocean. Two sets of 1960–2010 ensemble transient simulations are conducted with the coupled ocean version of the Goddard Earth Observing System Model, version 5: one with interactive stratospheric chemistry and the other with prescribed ozone derived from the same interactive simulations. The model’s climatology is evaluated using observations and reanalysis. Comparison of the 1979–2010 climate trends between these two simulations reveals that interactive chemistry has important effects on climate change not only in the Antarctic stratosphere, troposphere, and surface, but also in the Southern Ocean and Antarctic sea ice. Interactive chemistry causes stronger Antarctic lower stratosphere cooling and circumpolar westerly acceleration during November–January. It enhances stratosphere–troposphere coupling and leads to significantly larger tropospheric and surface westerly changes. The significantly stronger surface wind stress trends cause larger increases of the Southern Ocean meridional overturning circulation, leading to year-round stronger ocean warming near the surface and enhanced Antarctic sea ice decrease.

scholarly journals Stratospheric Ozone Depletion: The Main Driver of Twentieth-Century Atmospheric Circulation Changes in the Southern Hemisphere

2011 ◽  
Vol 24 (3) ◽  
pp. 795-812 ◽  
Author(s):  
Lorenzo M. Polvani ◽  
Darryn W. Waugh ◽  
Gustavo J. P. Correa ◽  
Seok-Woo Son
Keyword(s):  
Twentieth Century ◽  
Greenhouse Gases ◽  
Atmospheric Circulation ◽  
Southern Hemisphere ◽  
Ozone Depletion ◽  
General Circulation ◽  
Stratospheric Ozone ◽  
Hadley Cell ◽  
Stratospheric Ozone Depletion ◽  
Circulation Changes

Abstract The importance of stratospheric ozone depletion on the atmospheric circulation of the troposphere is studied with an atmospheric general circulation model, the Community Atmospheric Model, version 3 (CAM3), for the second half of the twentieth century. In particular, the relative importance of ozone depletion is contrasted with that of increased greenhouse gases and accompanying sea surface temperature changes. By specifying ozone and greenhouse gas forcings independently, and performing long, time-slice integrations, it is shown that the impacts of ozone depletion are roughly 2–3 times larger than those associated with increased greenhouse gases, for the Southern Hemisphere tropospheric summer circulation. The formation of the ozone hole is shown to affect not only the polar tropopause and the latitudinal position of the midlatitude jet; it extends to the entire hemisphere, resulting in a broadening of the Hadley cell and a poleward extension of the subtropical dry zones. The CAM3 results are compared to and found to be in excellent agreement with those of the multimodel means of the recent Coupled Model Intercomparison Project (CMIP3) and Chemistry–Climate Model Validation (CCMVal2) simulations. This study, therefore, strongly suggests that most Southern Hemisphere tropospheric circulation changes, in austral summer over the second half of the twentieth century, have been caused by polar stratospheric ozone depletion.

Shedding new light on the radiative impacts of ozone-depleting substances

2020 ◽  
Author(s):  
Gabriel Chiodo ◽  
Lorenzo M. Polvani
Keyword(s):  
Twentieth Century ◽  
Ozone Depletion ◽  
Stratospheric Ozone ◽  
Walker Circulation ◽  
Climate Impacts ◽  
The Arctic ◽  
Temperature Structure ◽  
Stratospheric Ozone Depletion ◽  
Ozone Depleting Substances ◽  
The Walker Circulation

<p>It is well established that ozone-depleting substances (ODS) have been the primary cause of stratospheric ozone depletion. It is also widely accepted that stratospheric ozone depletion has been the primary driver of summertime circulation trends in the Austral Hemisphere in the second half of the twentieth century. However, the climate impacts of ODS that are independent of ozone depletion have received little attention. It has long been known that, while much less abundant than carbon dioxide, ODS have a much higher global warming potential (GWP) ecent studies have indicated that ODS may have played a key-role in the observed weakening trends of the Walker circulation (Polvani and Bellomo, 2019), and in the warming of the Arctic and the associated sea ice loss (Polvani et al., 2020). <span>that the climate efficacy of ODS may be much larger than previously thought, but </span><span>.</span></p><p>Here, we seek to better understand the radiative effect of ODS in the global atmosphere. Instead of confining our attention on a single metric, e.g. globally averaged radiative forcing (RF) or GWP which are typically reported in the IPCC Assessment Reports, we seek to understand how ODS alter the temperature structure of the entire atmosphere. Focusing on the half-century 1950-2000, which saw the largest growth of ODS concentrations in the atmosphere, we start by performing careful computations of the RF of individual ODS, including the effects of rapid temperature adjustments. We then explore how the vertical and latitudinal distribution of ODS (which are not well mixed in the stratosphere) affects their RF, and what temperature responses are associated with those changes. These calculations are repeated individually for each of the other well-mixed GHG, as well as for other composition changes arising from ODS (ozone depletion). It is shown that ODS, in contrast to other GHG, warm the lower stratosphere, implying a different fingerprint from CO2. Furthermore, the RF of ODS exhibits the largest meridional gradient of any other well-mixed GHG. Implications for the climate efficacy of ODS, and more generally for climate sensitivity, will be discussed.</p><p>References</p><p>Polvani, L.M and K. Bellomo: The key role of ozone depleting substances in weakening the Walker circulation in the second half of the 20th century, <em>J. Climate</em>, <strong>32</strong>, 1411-1418 (2019).</p><p>Polvani et al.,: Substantial twentieth-century Arctic warmng caused by ozone depleting substances, <em>Nature Climate Change, </em>in press (2019)</p>

Nine Centuries of Man

2017 ◽  
Keyword(s):  
Twentieth Century ◽  
Diverse Range ◽  
Gender Expectations ◽  
Court Records ◽  
The Past ◽  
Wide Range ◽  
Police Reports ◽  
Late Twentieth ◽  
Scottish History ◽  
Late Twentieth Century

What did it mean to be a man in Scotland over the past nine centuries? Scotland, with its stereotypes of the kilted warrior and the industrial ‘hard man’, has long been characterised in masculine terms, but there has been little historical exploration of masculinity in a wider context. This interdisciplinary collection examines a diverse range of the multiple and changing forms of masculinities from the late eleventh to the late twentieth century, exploring the ways in which Scottish society through the ages defined expectations for men and their behaviour. How men reacted to those expectations is examined through sources such as documentary materials, medieval seals, romances, poetry, begging letters, police reports and court records, charity records, oral histories and personal correspondence. Focusing upon the wide range of activities and roles undertaken by men – work, fatherhood and play, violence and war, sex and commerce – the book also illustrates the range of masculinities that affected or were internalised by men. Together, the chapters illustrate some of the ways Scotland’s gender expectations have changed over the centuries and how, more generally, masculinities have informed the path of Scottish history

FOLLIES: ARCHITECTURE FOR THE LATE TWENTIETH CENTURY LANDSCAPE

1985 ◽  
Vol 4 (2) ◽  
pp. 140-141
Author(s):  
Anthony Vidler
Keyword(s):  
Twentieth Century ◽  
Late Twentieth ◽  
Late Twentieth Century

Trey Ellis's Platitudes: Redefining Black Voices

2009 ◽  
Vol 32 (1) ◽  
pp. 55-76
Author(s):  
Quan Manh Ha
Keyword(s):  
Twentieth Century ◽  
African American ◽  
American Literature ◽  
African American Literature ◽  
Black Experience ◽  
Racial Issues ◽  
Black Voices ◽  
Late Twentieth ◽  
One Year ◽  
Late Twentieth Century

Trey Ellis has emerged as a prominent African American writer of the late-twentieth century, despite the small number of his published works. “The New Black Aesthetic,” an essay that he first published in CaUaloo in 1989, one year after the publication of his first novel, Platitudes, stands as a manifesto that defines and articulates his perspective on the emerging black literary voices and culture of the time, and on “the future of African American artistic expression” in the postmodern era.1 According to Eric Lott, Ellis's novel parodies the literary and cultural conflict between such male experimental writers as lshmael Reed and such female realist writers as Alice Walker.2 Thus, Ellis's primary purpose in writing Platitudes is to redefine how African Americans should be represented in fiction, implying that neither of the dominant approaches can completely articulate late-twentieth-century black experience when practiced in isolation. In its final passages, Platitudes represents a synthesis of the two literary modes or styles, and it embodies quite fully the diversity of black cultural identities at the end of the twentieth century as it extends African American literature beyond racial issues. In this way, the novel exemplifies the literary agenda that Ellis suggests in his theoretical essay.

A New Denominational Historiography?

1995 ◽  
Vol 5 (2) ◽  
pp. 249-263
Author(s):  
John F. Wilson
Keyword(s):  
Twentieth Century ◽  
Recent Analysis ◽  
General Factor ◽  
Religious Organization ◽  
Religious Institution ◽  
Large Numbers ◽  
The Status ◽  
Late Twentieth ◽  
American Society ◽  
Late Twentieth Century

Over the last decade, a noteworthy number of published studies have, in one fashion or another, been defined with reference to religious denominations. This is an arresting fact, for, coincidentally, the status of religious denominations in the society has been called into question. Some formerly powerful bodies have lost membership (at least relatively speaking) and now experience reduced influence, while newer forms of religious organization(s)—e.g., parachurch groups and loosely structured movements—have flourished. The most compelling recent analysis of religion in modern American society gives relatively little attention to them. Why, then, have publications in large numbers appeared, in scale almost seeming to be correlated inversely to this trend?No single answer to this question is adequate. Surely one general factor is that historians often “work out of phase” with contemporary social change. If denominations have been displaced as a form of religious institution in society in the late twentieth century, then their prominence in earlier eras is all the more intriguing.

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