Global and Regional Climate Response to Late Twentieth-Century Warming over the Indian Ocean

2010 ◽  
Vol 23 (7) ◽  
pp. 1660-1674 ◽  
Author(s):  
James J. Luffman ◽  
Andréa S. Taschetto ◽  
Matthew H. England
Keyword(s):  
Twentieth Century ◽  
Indian Ocean ◽  
General Circulation ◽  
Regional Climate ◽  
Climate Response ◽  
Near Surface ◽  
Late Twentieth ◽  
Drying Trend ◽  
The Indian Ocean ◽  
Late Twentieth Century

Abstract The global and regional climate response to a warming of the Indian Ocean is examined in an ensemble of atmospheric general circulation model experiments. The most marked changes occur over the Indian Ocean, where the increase in tropical SST is found to drive enhanced convection throughout the troposphere. In the extratropics, the warming Indian Ocean is found to induce a significant trend toward the positive phase of the northern annular mode and also to enhance the Southern Hemisphere storm track over Indian Ocean longitudes as a result of stronger meridional temperature gradients. Convective outflow in the upper levels over the warming Indian Ocean leads to a trend in subsidence over the Indian and Asian monsoon regions extending southeastward to Indonesia, the eastern Pacific, and northern Australia. Regional changes in Australia reveal that this anomalous zone of subsidence induces a drying trend in the northern regions of the continent. The long-term rainfall trend is exacerbated over northeastern Australia by the anomalous anticyclonic circulation, which leads to an offshore trend in near-surface winds. The confluence of these two factors leads to a drying signal over northeastern Australia, which is detectable during austral autumn. The rapid, late twentieth-century warming of the Indian Ocean may have contributed to a component of the observed drying trend over northeastern Australia in this season via modifications to the vertical structure of the tropical wind field.

Cryostratigraphic record of permafrost degradation and recovery following historic (1898–1992) surface disturbances in the Klondike region, central Yukon Territory1This article is one of a series of papers published in this CJES Special Issue on the theme of Fundamental and applied research on permafrost in Canada.2Yukon Geological Survey Contribution 008.

2012 ◽  
Vol 49 (8) ◽  
pp. 938-952 ◽  
Author(s):  
Fabrice Calmels ◽  
Duane G. Froese ◽  
Wendy R. Clavano
Keyword(s):  
Twentieth Century ◽  
Gold Rush ◽  
Yukon Territory ◽  
Forest Site ◽  
Permafrost Degradation ◽  
Near Surface ◽  
Discontinuous Permafrost ◽  
Late Twentieth ◽  
Undisturbed Forest ◽  
Late Twentieth Century

We present a detailed cryostratigraphic reconstruction of the degradation and recovery of near-surface permafrost in the southern Klondike goldfields, central Yukon Territory. Two ice-rich layers are recognized in near-surface permafrost and attributed to thermal impacts following vegetation disturbance. At an undisturbed forest site, the base of the modern active layer is stable. At an adjacent site, where a late twentieth century disturbance of surface vegetation and permafrost degradation occurred, there is evidence of recovery in the form of aggradation (upward shift) of the permafrost table following limited vegetation succession. Underlying both the undisturbed forest and the late twentieth century disturbance is an older thaw unconformity corresponding to a thaw depth of ∼2 m, likely associated with early twentieth century (gold rush era) impacts. Field and air photo surveys allow identification of the nature of the disturbances, while a chronology of the surface disturbance has been established using age estimates from tree rings, and the presence of tritium and post-bomb 14C from organic samples within aggradational ice. Collectively, these data underscore the importance of vegetation cover in maintaining ground temperatures in the discontinuous permafrost zone and suggest that, at least at the study site in recent decades, permafrost shows the potential to recover from disturbance in the modern climatic regime of the region.

scholarly journals Higher Hydroclimatic Intensity with Global Warming

2011 ◽  
Vol 24 (20) ◽  
pp. 5309-5324 ◽  
Author(s):  
F. Giorgi ◽  
E.-S. Im ◽  
E. Coppola ◽  
N. S. Diffenbaugh ◽  
X. J. Gao ◽  
...  
Keyword(s):  
Twentieth Century ◽  
Global Warming ◽  
Climate Model ◽  
Regional Climate ◽  
Precipitation Intensity ◽  
Detection And Attribution ◽  
Dry Spell ◽  
Late Twentieth ◽  
Late Twentieth Century ◽  
Spell Length

Abstract Because of their dependence on water, natural and human systems are highly sensitive to changes in the hydrologic cycle. The authors introduce a new measure of hydroclimatic intensity (HY-INT), which integrates metrics of precipitation intensity and dry spell length, viewing the response of these two metrics to global warming as deeply interconnected. Using a suite of global and regional climate model experiments, it is found that increasing HY-INT is a consistent and ubiquitous signature of twenty-first-century, greenhouse gas–induced global warming. Depending on the region, the increase in HY-INT is due to an increase in precipitation intensity, dry spell length, or both. Late twentieth-century observations also exhibit dominant positive HY-INT trends, providing a hydroclimatic signature of late twentieth-century warming. The authors find that increasing HY-INT is physically consistent with the response of both precipitation intensity and dry spell length to global warming. Precipitation intensity increases because of increased atmospheric water holding capacity. However, increases in mean precipitation are tied to increases in surface evaporation rates, which are lower than for atmospheric moisture. This leads to a reduction in the number of wet days and an increase in dry spell length. This analysis identifies increasing hydroclimatic intensity as a robust integrated response to global warming, implying increasing risks for systems that are sensitive to wet and dry extremes and providing a potential target for detection and attribution of hydroclimatic changes.

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

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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