scholarly journals Near-Surface Salinity as Nature’s Rain Gauge to Detect Human Influence on the Tropical Water Cycle

2012 ◽  
Vol 25 (3) ◽  
pp. 958-977 ◽  
Author(s):  
Laurent Terray ◽  
Lola Corre ◽  
Sophie Cravatte ◽  
Thierry Delcroix ◽  
Gilles Reverdin ◽  
...  
Keyword(s):  
Climate Change ◽  
Water Cycle ◽  
Internal Variability ◽  
Human Influence ◽  
Surface Salinity ◽  
Near Surface ◽  
Salinity Changes ◽  
Tropical Water ◽  
Late Twentieth ◽  
Late Twentieth Century

Abstract Changes in the global water cycle are expected as a result of anthropogenic climate change, but large uncertainties exist in how these changes will be manifest regionally. This is especially the case over the tropical oceans, where observed estimates of precipitation and evaporation disagree considerably. An alternative approach is to examine changes in near-surface salinity. Datasets of observed tropical Pacific and Atlantic near-surface salinity combined with climate model simulations are used to assess the possible causes and significance of salinity changes over the late twentieth century. Two different detection methodologies are then applied to evaluate the extent to which observed large-scale changes in near-surface salinity can be attributed to anthropogenic climate change. Basin-averaged observed changes are shown to enhance salinity geographical contrasts between the two basins: the Pacific is getting fresher and the Atlantic saltier. While the observed Pacific and interbasin-averaged salinity changes exceed the range of internal variability provided from control climate simulations, Atlantic changes are within the model estimates. Spatial patterns of salinity change, including a fresher western Pacific warm pool and a saltier subtropical North Atlantic, are not consistent with internal climate variability. They are similar to anthropogenic response patterns obtained from transient twentieth- and twenty-first-century integrations, therefore suggesting a discernible human influence on the late twentieth-century evolution of the tropical marine water cycle. Changes in the tropical and midlatitudes Atlantic salinity levels are not found to be significant compared to internal variability. Implications of the results for understanding of the recent and future marine tropical water cycle changes are discussed.

Ocean Salinity changes in the global ocean under global warming conditions Part 1: Mechanisms in a strong warming scenario

2021 ◽  
pp. 1-56
Author(s):  
Anju Sathyanarayanan ◽  
Armin Köhl ◽  
Detlef Stammer
Keyword(s):  
Large Scale ◽  
Water Cycle ◽  
Spatial Scales ◽  
Sea Surface Salinity ◽  
Global Ocean ◽  
Dynamical Response ◽  
Freshwater Flux ◽  
Near Surface ◽  
Salinity Changes ◽  
Circulation Changes

AbstractWe investigate mechanisms underlying salinity changes projected to occur under strong representative concentration pathway (RCP) 8.5 forcing conditions. The study is based on output of the Max Planck Institute Earth System Model Mixed Resolution (MPI-ESM-MR) run with an ocean resolution of 0.4°. In comparison to the present-day oceanic conditions, sea surface salinity (SSS) increases towards the end of the 21st century in the tropical and the subtropical Atlantic. In contrast, a basin-wide surface freshening can be observed in the Pacific and Indian Oceans. The RCP8.5 scenario of the MPI-ESM-MR with a global surface warming of ~2.3°C marks a water cycle amplification of 19 %, which is equivalent to ~8%°C−1 and thus close to the water cycle amplification predicted according to the Clausius–Clapeyron (CC) relationship (~7%°C−1). Large scale global SSS changes are driven by adjustments of surface freshwater fluxes. On smaller spatial scales, it is predominantly advection related to circulation changes that affects near-surface SSS. With respect to subsurface salinity, it is changes in surface freshwater flux that drive their changes over the upper 500 m of the subtropical Pacific and Indian oceans by forcing changes in water mass formation (spice signal). In the subtropical Atlantic Ocean, in contrast, the dynamical response associated with wind stress, circulation changes and associated heaving of isopycnals is equally important in driving subsurface salinity changes over the upper 1000 m.

Historical Perspectives on Climate Change

1998 ◽  
Author(s):  
James R. Fleming
Keyword(s):  
Climate Change ◽  
Global Climate ◽  
Early America ◽  
Temperature Changes ◽  
Historical Perspectives ◽  
The Past ◽  
The Enlightenment ◽  
Late Twentieth ◽  
Late Twentieth Century ◽  
Field Of Inquiry

This intriguing volume provides a thorough examination of the historical roots of global climate change as a field of inquiry, from the Enlightenment to the late twentieth century. Based on primary and archival sources, the book is filled with interesting perspectives on what people have understood, experienced, and feared about the climate and its changes in the past. Chapters explore climate and culture in Enlightenment thought; climate debates in early America; the development of international networks of observation; the scientific transformation of climate discourse; and early contributions to understanding terrestrial temperature changes, infrared radiation, and the carbon dioxide theory of climate. But perhaps most important, this book shows what a study of the past has to offer the interdisciplinary investigation of current environmental problems.

scholarly journals Turbulence within rain-formed fresh lenses during the SPURS-2 Experiment

2021 ◽  
Author(s):  
Suneil Iyer ◽  
Kyla Drushka
Keyword(s):  
Water Cycle ◽  
Regional Study ◽  
Surface Salinity ◽  
Near Surface ◽  
Turbulent Dissipation ◽  
Wind Speeds ◽  
Dissipation Rates ◽  
Wide Range ◽  
Surface Turbulence ◽  
Primary Driver

AbstractObservations of salinity, temperature, and turbulent dissipation rate were made in the top meter of the ocean using the ship-towed Surface Salinity Profiler as part of the second Salinity Processes in the Upper Ocean Regional Study (SPURS-2) to assess the relationships between wind, rain, near-surface stratification, and turbulence. A wide range of wind and rain conditions were observed in the eastern tropical Pacific Ocean near 10°N, 125°W in summer-autumn 2016 and 2017. Wind was the primary driver of near-surface turbulence and the mixing of rain-formed fresh lenses, with lenses generally persisting for hours when wind speeds were under 5 m s−1 and mixing away immediately at higher wind speeds. Rain influenced near-surface turbulence primarily through stratification. Near-surface stratification caused by rainfall or diurnal warming suppressed deeper turbulent dissipation rates when wind speeds were under 3 m s−1. In one case with 4-5 m s−1 winds, rain-induced stratification enhanced dissipation rates within the stratified layer. At wind speeds above 7-8 m s−1, strong stratification was not observed in the upper meter during rain, indicating that rain lenses do not form at wind speeds above 8 m s−1. Raindrop impacts enhanced turbulent dissipation rates at these high wind speeds in the absence of near-surface stratification. Measurements of air-sea buoyancy flux, wind speed, and near-surface turbulence can be used to predict the presence of stratified layers. These findings could be used to improve model parameterizations of air-sea interactions and, ultimately, our understanding of the global water cycle.

Picturing Climate Change: “It’s the Apocalypse”

2021 ◽  
pp. 193-206
Author(s):  
Miles Orvell
Keyword(s):  
Climate Change ◽  
Hurricane Katrina ◽  
New Orleans ◽  
Henry David Thoreau ◽  
Time Lapse ◽  
Ecological Awareness ◽  
Gulf States ◽  
Late Twentieth ◽  
Late Twentieth Century ◽  
Climate Disaster

Ecological awareness goes back at least to Henry David Thoreau in the mid-nineteenth century, but it is only in the late twentieth century that a broader awareness emerged, centering on the effects of a changing climate on the Earth’s surface. The cataclysmic terror of Hurricane Katrina was most vividly photographed by Robert Polidori, among a dozen other New Orleans photographers, and his work is examined in this chapter. A different approach is taken by John Ganis, who has concentrated on the coastal regions of the East and Gulf states and has provided the perspective of a long-range view. Both photographers reveal the fragility of material structures, in which the movement from order to chaos can create shocking images of our disrupted environment. Yet another perspective is taken in the work of James Balog, whose time-lapse photographs and movies have disclosed the melting of polar glaciers at a speed that has startled scientists, even while it has confirmed the worst fears of climate change and the ruins it entails. The chapter concludes with a consideration of the way two popular climate movies by Roland Emmerich have imagined climate disaster, and the ambiguities of such representations.

What Is Culture For?

2019 ◽  
pp. 123-160 ◽  
Author(s):  
Yoshihisa Kashima
Keyword(s):  
Climate Change ◽  
Critical Role ◽  
First Century ◽  
Historical Background ◽  
Environmental Niche ◽  
Theoretical Approaches ◽  
Late Twentieth ◽  
Late Nineteenth ◽  
Intergroup Conflicts ◽  
Late Twentieth Century

What is culture for? What functions does culture serve? This chapter traces a historical background to these functionalist questions and examine their contemporary relevance. Although functionalist perspectives arose from Darwin’s evolutionism in social science and psychology of the late nineteenth and early twentieth centuries, their theoretical implications were thoroughly criticized and gave way to the emergence of a newer, neo-functionalist thinking in the late twentieth century. A neo-functionalist perspective is discernible in a variety of theoretical approaches in culture and psychology. Its basic tenet suggests that culture is often, though not always, helpful for its adopters to adapt to their local environmental niche, meeting different types of environmental challenges, both natural and human made (built, economic, intergroup, intragroup, psychological). The chapter concludes by advocating that research on culture and psychology can play a critical role in helping humanity meet the twenty-first-century challenges of climate change and intergroup conflicts.

scholarly journals Simulating the Role of Surface Forcing on Observed Multidecadal Upper-Ocean Salinity Changes

2016 ◽  
Vol 29 (15) ◽  
pp. 5575-5588 ◽  
Author(s):  
Véronique Lago ◽  
Susan E. Wijffels ◽  
Paul J. Durack ◽  
John A. Church ◽  
Nathaniel L. Bindoff ◽  
...  
Keyword(s):  
Water Cycle ◽  
Three Dimensional ◽  
Ocean Model ◽  
Salinity Change ◽  
Surface Salinity ◽  
Qualitative Comparison ◽  
Salinity Field ◽  
Temperature Changes ◽  
Surface Warming ◽  
Salinity Changes

Abstract The ocean’s surface salinity field has changed over the observed record, driven by an intensification of the water cycle in response to global warming. However, the origin and causes of the coincident subsurface salinity changes are not fully understood. The relationship between imposed surface salinity and temperature changes and their corresponding subsurface changes is investigated using idealized ocean model experiments. The ocean’s surface has warmed by about 0.5°C (50 yr)−1 while the surface salinity pattern has amplified by about 8% per 50 years. The idealized experiments are constructed for a 50-yr period, allowing a qualitative comparison to the observed salinity and temperature changes previously reported. The comparison suggests that changes in both modeled surface salinity and temperature are required to replicate the three-dimensional pattern of observed salinity change. The results also show that the effects of surface changes in temperature and salinity act linearly on the changes in subsurface salinity. Surface salinity pattern amplification appears to be the leading driver of subsurface salinity change on depth surfaces; however, surface warming is also required to replicate the observed patterns of change on density surfaces. This is the result of isopycnal migration modified by the ocean surface warming, which produces significant salinity changes on density surfaces.

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 Sounds Real and Imagined:

2020 ◽  
Vol 18 (1) ◽  
pp. 99-110
Author(s):  
Denise Ruth Von Glahn
Keyword(s):  
Climate Change ◽  
Twentieth Century ◽  
Natural World ◽  
First Century ◽  
Aesthetic Responses ◽  
Early Twenty ◽  
Libby Larsen ◽  
Late Twentieth ◽  
The Impact ◽  
Late Twentieth Century

In a career spanning more than four decades, American composer Libby Larsen has turned to the natural world for inspiration on dozens of occasions: her piece Up Where the Air Gets Thin is just one of the results. Unlike many of her nature-based works which provide primarily aesthetic responses to the sights, sounds, feel, and smells of the natural environment, this 1985 duet for contrabass and cello comments on the limits of non-verbal communication and the impact of climate change. It is simultaneously reflective and didactic. “Sounds Real and Imagined” considers the ways Larsen marshals minimal musical materials and a sonic vocabulary that she associates with stillness and cold, in combination with her commitment to environmental awareness and advocacy. It situates the historic 1953 ascent of Mt. Everest by Sir Edmund Hillary and Tensing Norgay within the context of late-twentieth-century artistic responses and an early twenty-first century musicologist-listener’s consciousness.

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.

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