Download or read book Fluctuations of the West Greenland Ice Sheet Independent Ice Caps and Mountain Glaciers During the Twentieth Century written by and published by . This book was released on 2010 with total page 205 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Greenland Ice Sheet contains enough water to raise global sea levels by ~7 metres, but predictions of the actual potential future contribution in a warming climate vary widely. These can be improved through a better understanding of how the whole ice sheet and its outlet glaciers have responded to past and present climate fluctuations. Recent studies have observed that Greenland Ice Sheet outlet glaciers have been retreating and thinning at increasingly faster rates since the 1990s. However, few studies have investigated the behaviour of the numerous independent ice caps that surround the ice sheet, or the land-terminating outlet glaciers. In addition, recent retreat is rarely put into context with long-term twentieth century fluctuations. This study has mapped ice sheet outlet glaciers and margins, independent ice cap outlets and mountain/valley glaciers at 11 time steps between the Little Ice Age and 2009 in northwest and southwest Greenland. Length changes of different glacier classes and terminus environments are examined, and overall glacier fluctuations compared to regional air temperatures and precipitation. Glaciers in the northwest have retreated further than those in the southwest at most time periods, with the exception of 1943/53-1964 when southwest glaciers underwent their most rapid rate of retreat. Length changes in both regions are driven by air temperature and precipitation changes. Tidewater outlet glaciers have generally retreated shorter distances than land-terminating glaciers in both absolute and relative terms over long time periods. These results imply that recent rapid retreat of many tidewater outlet glaciers in Greenland is not unprecedented, and may represent natural cyclical fluctuations rather than a long-term shift in behaviour. Ice sheet outlet glaciers have retreated shorter relative distances than independent ice caps and mountain/valley glaciers. Ice sheet margins advanced in the southwest between 1964 and 2001, and a slight and a slight advance of independent glaciers was observed from ~1964-1987. It is unclear why this advance occurred. This study highlights the need for more research into the fluctuations of the independent ice caps and land-terminating glaciers in all regions of Greenland. In addition, more detailed research into the response of glaciers of all classes and terminus environments to climate change during the whole of the twentieth century is required to put recent changes into context.
Download or read book Late Glacial and Holocene Fluctuations of Local Glaciers and the Greenland Ice Sheet Eastern and Western Greenland written by Laura B. Levy and published by . This book was released on 2014 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The Greenland Ice Sheet (GrIS) is responding sensitively to climate change and its meltwater has the potential to influence global sea level. Recently, large changes in the GrIS have occurred including increased velocities of outlet glaciers and melt over ~97% of the ice sheet. One means to understand modern and help predict future changes in the GrIS is to examine how it responded to past climate conditions. In this dissertation I provide a longer-term perspective of changes in the GrIS as well as in smaller, independent glaciers near the ice sheet margins (i.e., "local" glaciers). My research documents the past extents of the GrIS in central East and southern West Greenland during the Holocene Epoch (11,600 yrs ago-present) and provides evidence for climate conditions along the ice sheet margin during late glacial time (~17,500-11,600 yrs ago) and the Holocene Epoch. I use geomorphic mapping, surface exposure dating and lake sediment analyses to demonstrate that the GrIS and local glaciers in central East Greenland were receding during the Younger Dryas cold event (~12,900-11,600 yrs ago) and deposited the Milne Land stade moraines at the end of the Younger Dryas. I hypothesize that these ice marginal fluctuations were primarily influenced by air or ocean surface temperatures. I document the Holocene fluctuations of a local glacier that completely disappeared indicating peak warm conditions between ~9.3 and 6.0 cal kyr BP. The formation of this glacier at 2.6 cal kyr BP and its persistence from ~1.9 cal kyr BP-present suggests cold conditions during late Holocene time. I also use geomorphic mapping and surface exposure dating to document the extents of the GrIS in southern West Greenland, near Kangerlussuaq. I show that the Keglen, Ørkendalen and Historical moraines were deposited at 7.3 ka, 6.3 ka, and by ~AD 1950, respectively. These data indicate that the GrIS was as small as or smaller than at present during much of middle to late Holocene time. Finally, I synthesize my results and discuss possible causes of GrIS marginal changes in central East and southern West Greenland including changes in air and ocean temperatures and changes in sea level."
Download or read book Vanishing Ice written by Vivien Gornitz and published by Columbia University Press. This book was released on 2019-06-11 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Arctic is thawing. In summer, cruise ships sail through the once ice-clogged Northwest Passage, lakes form on top of the Greenland Ice Sheet, and polar bears swim farther and farther in search of waning ice floes. At the opposite end of the world, floating Antarctic ice shelves are shrinking. Mountain glaciers are in retreat worldwide, unleashing flash floods and avalanches. We are on thin ice—and with melting permafrost’s potential to let loose still more greenhouse gases, these changes may be just the beginning. Vanishing Ice is a powerful depiction of the dramatic transformation of the cryosphere—the world of ice and snow—and its consequences for the human world. Delving into the major components of the cryosphere, including ice sheets, valley glaciers, permafrost, and floating ice, Vivien Gornitz gives an up-to-date explanation of key current trends in the decline of ice mass. Drawing on a long-term perspective gained by examining changes in the cryosphere and corresponding variations in sea level over millions of years, she demonstrates the link between thawing ice and sea-level rise to point to the social and economic challenges on the horizon. Gornitz highlights the widespread repercussions of ice loss, which will affect countless people far removed from frozen regions, to explain why the big meltdown matters to us all. Written for all readers and students interested in the science of our changing climate, Vanishing Ice is an accessible and lucid warning of the coming thaw.
Download or read book Satellite Image Atlas of Glaciers of the World Asia U S Geological Survey Professional Paper 1386 F written by U.S. Geological Survey and published by . This book was released on 2012-11-01 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Glaciers and Environmental Change written by Atle Nesje and published by Routledge. This book was released on 2016-04-29 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: This authoritative new text provides a thorough, updated account of glaciers and ice sheets as monitors and indicators of environmental change. It examines the record of environmental change within glaciers and ice sheets, and that of past environments left by retreating glaciers. These themes are examined within the context of environmental change in general and global climate change in particular. Methods of using palaeoenvironmental records are assessed and the implications for future environmental change are discussed. Evidence from glacier ice left in the landscape or within the geological record, provides one of the most important sources of information on environmental change. 'Glaciers and Environmental Change' is a comprehensive account of glaciers andice sheets as monitors and indictaors of environmental change. Based on the latest research, this book consolidates a diverse range of data and explains their applications. it also assesses methods of using palaeoenvironmental records. This authoritative new text examines not only the records of environmental change within glaciers but also that of past environments left by retreating glaciers. These themes are examined within the context of contemporary debates in environmental change and the volume also seeks to draw conclusions concernign past, present and future climatic change in relation to glaciers.
Download or read book Reconstructing Ice Sheet and Alpine Glacier Margins During the Early Holocene on Nuussuaq in Central West Greenland written by Sandra L. Cronauer and published by . This book was released on 2014 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comparison of past ice sheet margin and alpine glacier reconstructions to paleoclimate records can offer insight into the dominant forcing mechanisms that determine glacial response to changes in climate. Previous research on a major ice stream in central West Greenland reveals that the Greenland Ice Sheet (GrIS) responded to abrupt centennial-scale cold periods at ~9. 3 and ~8. 2 ka. The aim of this thesis is to determine whether or not alpine glaciers and a land-terminating ice sheet margin on the peninsula of Nuussuaq in central West Greenland also responded to abrupt climate changes in the early Holocene. To this end, I reconstructed ice sheet and alpine glacier histories on Nuussuaq using cosmogenic 10Be surface exposure dating (herein 10Be dating) and lake sediment analysis. Neither the ice margin nor alpine glacier chronologies indicate a response to abrupt climate change at 9. 3 ka or 8. 2 ka. I found that the Drygalski Moraines are early Holocene in age, with mean moraine ages of 8. 6 ℗ł 0. 4 ka (n=2), 8. 5 ℗ł 0. 2 ka (n=3), and 7. 6 ℗ł 0. 1 ka (n=2) from outer to inner. The moraine chronology, combined with radiocarbon dated lake sediment stratigraphy from an adjacent proglacial lake, reveal that the ice margin remained within about one kilometer of its present position from ~9. 9 to 5. 4 ka. This evidence for ice sheet stability during the first half of the Holocene, followed by minimum ice extent between ~5. 4 and 0. 6 ka, contrasts with many records of early Holocene warmth during the Holocene maximum of Northern Hemisphere summer insolation. This period of ice margin stability may relate to adjacent ocean temperatures, which did not increase until the middle Holocene. A 10Be chronology of moraines deposited by a nearby alpine glacier reveals glacier stability at 10. 5 ℗ł 0. 3 ka, during the Preboreal period. Moraine deposition at this time is potentially due to increased moisture availability as the GrIS retreated and sea ice declined. The alpine glacier chronology also fits well within an emerging pattern of alpine glacier advance during the Preboreal period on East and West Greenland. The results presented in this thesis suggest that GrIS and alpine glacier margin response to changes in climate is complex, and that detailed chronologies from moraines on Greenland can shed light on the intricate processes that link glaciers and climate.
Download or read book Effects of Carbon Dioxide Buildup in the Atmosphere written by United States. Congress. Senate. Committee on Energy and Natural Resources and published by . This book was released on 1980 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Glacier Fluctuations and Climatic Change written by Johannes Oerlemans and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the Symposium on Glacier Fluctuations and Climatic Change, held in Amsterdam, June 1-5, 1987
Download or read book Polar Environments and Global Change written by Roger G. Barry and published by Cambridge University Press. This book was released on 2018-08-09 with total page 445 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surveys atmospheric, oceanic and cryospheric processes, present and past conditions, and changes in polar environments.
Download or read book When the Ice Is Gone What a Greenland Ice Core Reveals About Earth s Tumultuous History and Perilous Future written by Paul Bierman and published by W. W. Norton & Company. This book was released on 2024-08-20 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: Paul Bierman’s realization that Greenland’s ice sheet melted when Earth was no warmer than today sounds an alarm for our planet. In 2018, lumps of frozen soil, collected from the bottom of the world’s first deep ice core and lost for decades, reappeared in Denmark. When geologist Paul Bierman and his team first melted a piece of this unique material, they were shocked to find perfectly preserved leaves, twigs, and moss. That observation led them to a startling discovery: Greenland’s ice sheet had melted naturally before, about 400,000 years ago. The remote island’s ice was far more fragile than scientists had realized—unstable even without human interference. In When the Ice Is Gone, Bierman traces the story of this extraordinary finding, revealing how it radically changes our understanding of the Earth and its climate. A longtime researcher in Greenland, he begins with a brief history of the island, both human and geological, explaining how over the last century scientists have learned to read the historical record in ice, deciphering when volcanoes exploded and humans started driving cars fueled by leaded gasoline. For the origins of ice coring, Bierman brings us to Camp Century, a U.S. military base built inside Greenland’s ice sheet, where engineers first drilled through mile-thick ice and into the frozen soil beneath. Decades later, a few feet of that long-frozen earth would reveal its secrets—ancient warmth and melted ice. Changes in Greenland reverberate around the world, with ice melting high in the arctic affecting people everywhere. Bierman explores how losing Greenland’s ice will catalyze devastating events if we don’t change course and address climate change now.
Download or read book Holocene Ice Margin Fluctuations of the Greenland Ice Sheet in the Disko Bugt Region West Greenland written by and published by . This book was released on 2014 with total page 173 pages. Available in PDF, EPUB and Kindle. Book excerpt: The current response of the Greenland Ice Sheet (GrIS) margin to climate change is spatially and temporally variable. Understanding the mechanisms that control this variability is crucial for accurate predictions of how the GrIS will change in the future. One factor that appears to play a role in driving the varying response exhibited along the margin of the GrIS is the ice margin setting (marine-terminating or land-terminating). Recent research has demonstrated that basal melting of marine-terminating glaciers may increase their vulnerability to climatic perturbations, while their land-terminating counterparts may lag in their reaction similar climatic changes. While these trends are illustrated in historic and modern records, longer temporal records are needed to place these observations in context. Here, I present a chronology of GrIS fluctuations within the Disko Bugt region of West Greenland. This record spans the Holocene, and is constrained by 10Be and radiocarbon ages. Through building this chronology, I reconstruct the pattern and timing of Holocene ice margin fluctuations and evaluate the response of differing ice margin types (marine-based or land-based) to regional climate forcing. From my chronology it is apparent that, on millennial timescales early Holocene ice margin retreat rates were synchronous within Disko Bugt. This pattern extends along the western margin of the GrIS, with all the sections of the ice margin examined displaying similar retreat rates despite dissimilar marginal settings. This is strikingly different than modern trends, where marine-based outlet glaciers exhibit significantly higher retreat rates than their land-based counterparts. The record of ice margin reaction to recent warming demonstrates a distinct pattern of asynchrony. In my late Holocene records, marine-based glaciers initiate retreat much sooner than land-based sectors of the ice margin. I believe this feature demonstrates a relationship between ice margin type and response time. I propose that in West Greenland faster glaciers maintain a closer equilibrium with changing climate than slower flowing glaciers. In total, the historic pattern of relative stability of land-based sectors of the GrIS is in contrast with the longer records of Holocene ice margin fluctuation. Additionally, a relationship between ice margin type and response time suggests that land-based sectors of the ice margin lag in their reaction to climate forcing on decadal scales. This indicates that historically stable sectors of the ice margin may be expected to undergo significant future retreat, as a larger percentage of the GrIS margin begins to react to 20th century warming.
Download or read book The Ice at the End of the World written by Jon Gertner and published by . This book was released on 2019 with total page 449 pages. Available in PDF, EPUB and Kindle. Book excerpt: An urgent account of the explorers and scientists racing to understand the rapidly melting ice sheet in Greenland, a dramatic harbinger of climate change. As Greenland's ice melts and runs off into the sea, it not only threatens to affect hundreds of millions of people who live in coastal areas. It will also have drastic effects on ocean currents, weather systems, economies, and migration patterns
Download or read book Energy Management Partnership Act of 1979 written by United States. Congress. Senate. Committee on Energy and Natural Resources. Subcommittee on Energy Conservation and Supply and published by . This book was released on 1980 with total page 1308 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Greenland Outlet Glacier Behavior During the 21st Century written by Twila Moon and published by . This book was released on 2014 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: Outlet glacier ice dynamics, including ice-flow speed, play a key role in determining Greenland Ice Sheet mass loss, which is a significant contributor to global sea-level rise. Mass loss from the Greenland Ice Sheet increased significantly over the last several decades and current mass losses of 260-380 Gt ice/yr contribute 0.7-1.1 mm/yr to global sea-level rise (~10%). Understanding the potentially complex interactions among glacier, ocean, and climate, however, remains a challenge and limits certainty in modeling and predicting future ice sheet behavior and associated risks to society. This thesis focuses on understanding the seasonal to interannual scale changes in outlet glacier velocity across the Greenland Ice Sheet and how velocity fluctuations are connected to other elements of the ice sheet-ocean-atmosphere system. 1) Interannual velocity patterns Earlier observations on several of Greenland's outlet glaciers, starting near the turn of the 21st century, indicated rapid (annual-scale) and large (>100%) increases in glacier velocity. Combining data from several satellites, we produce a decade-long (2000 to 2010) record documenting the ongoing velocity evolution of nearly all (200+) of Greenland's major outlet glaciers, revealing complex spatial and temporal patterns. Changes on fast-flow marine-terminating glaciers contrast with steady velocities on ice-shelf-terminating glaciers and slow speeds on land-terminating glaciers. Regionally, glaciers in the northwest accelerated steadily, with more variability in the southeast and relatively steady flow elsewhere. Intraregional variability shows a complex response to regional and local forcing. Observed acceleration indicates that sea level rise from Greenland may fall well below earlier proposed upper bounds. 2) Seasonal velocity patterns. Greenland mass loss includes runoff of surface melt and ice discharge via marine-terminating outlet glaciers, the latter now making up a third to a half of total ice loss. The magnitude of ice discharge depends in part on ice-flow speed, which has broadly increased since 2000 but varies locally, regionally, and from year-to-year. Research on a few Greenland glaciers also shows that speed varies seasonally. However, for many regions of the ice sheet, including wide swaths of the west, northwest, and southeast coasts where ice loss is increasing most rapidly, there are few or no records of seasonal velocity variation. We present 5-year records of seasonal velocity measurements for 55 glaciers distributed around the ice sheet margin. We find 3 distinct seasonal velocity patterns. The different patterns indicate varying glacier sensitivity to ice-front (terminus) position and likely regional differences in basal hydrology in which some subglacial systems do transition seasonally from inefficient, distributed hydrologic networks to efficient, channelized drainage, while others do not. Our findings highlight the need for modeling and observation of diverse glacier systems in order to understand the full spectrum of ice-sheet dynamics. 3) Seasonal to interannual glacier and sea ice behavior and interaction Focusing on 16 northwestern Greenland glaciers during 2009-2012, we examine terminus position, sea ice and ice m??lange conditions, seasonal velocity changes, topography, and climate, with extended 1999-2012 records for 4 glaciers. There is a strong correlation between near-terminus sea ice/mélange conditions and terminus position. In several cases, late-forming and inconsistent sea ice/mélange may induce sustained retreat. For all of the 13-year records and most of the 4-year records, sustained, multi-year retreat is accompanied by velocity increase. Seasonal speedup, which is observed across the region, may, however, be more heavily influenced by melt interacting with the subglacial hydrologic system than seasonal terminus variation. Projections of continued warming and longer ice-free periods around Greenland suggest that notable retreat over wide areas may continue. Sustained retreat is likely to be associated with multi-year speedup, though both processes are modulated by local topography. The timing of seasonal ice dynamics patterns may also shift.
Download or read book The Ocean and Cryosphere in a Changing Climate written by Intergovernmental Panel on Climate Change (IPCC) and published by Cambridge University Press. This book was released on 2022-04-30 with total page 755 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Intergovernmental Panel on Climate Change (IPCC) is the leading international body for assessing the science related to climate change. It provides policymakers with regular assessments of the scientific basis of human-induced climate change, its impacts and future risks, and options for adaptation and mitigation. This IPCC Special Report on the Ocean and Cryosphere in a Changing Climate is the most comprehensive and up-to-date assessment of the observed and projected changes to the ocean and cryosphere and their associated impacts and risks, with a focus on resilience, risk management response options, and adaptation measures, considering both their potential and limitations. It brings together knowledge on physical and biogeochemical changes, the interplay with ecosystem changes, and the implications for human communities. It serves policymakers, decision makers, stakeholders, and all interested parties with unbiased, up-to-date, policy-relevant information. This title is also available as Open Access on Cambridge Core.
Download or read book Late Quaternary Ice ocean Interactions in Central West Greenland written by David John McCarthy and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A greater knowledge of the interactions between the Greenland Ice Sheet and climate is critical to understanding the possible impacts of future global warming, including ice sheet contribution to global sea-level rise and perturbations to ocean circulation. Recent acceleration, thinning and retreat of major tidewater glaciers in Greenland and Antarctica during the past two decades demonstrate the potential for ice sheets to respond to climate change much faster than previously assumed. One approach to understanding the role of atmospheric and oceanic warming to ice sheet dynamics is to investigate how ice sheets responded to past periods of climate change. This thesis uses benthic foraminifera as a proxy to reconstruct past changes in the temperature of the relatively warm West Greenland Current, to investigate the possible influence of ocean warming on ice sheet dynamics during the initial marine-based deglaciation phase, and throughout the Holocene, when the ice was positioned close to the present margin. This thesis finds that the marine-based ice sheet in central West Greenland collapsed rapidly due to a combination of high relative sea-level and ice sheet thinning due to climatic warming. Foraminiferal evidence does not support a major influence of ocean forcing on initial deglaciation. However, Holocene changes in the relative temperature of the West Greenland Current may have had a more significant influence on ice stream dynamics following the marine-based ice retreat, when outlet glaciers were positioned within coastal fjords. Changes in the relative temperature of the West Greenland Current are determined?upstream? by wider scale changes in the North Atlantic region.
Download or read book Glacier Science and Environmental Change written by Peter G. Knight and published by John Wiley & Sons. This book was released on 2008-04-15 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt: Glacier Science and Environmental Change is an authoritative and comprehensive reference work on contemporary issues in glaciology. It explores the interface between glacier science and environmental change, in the past, present, and future. Written by the world’s foremost authorities in the subject and researchers at the scientific frontier where conventional wisdom of approach comes face to face with unsolved problems, this book provides: state-of-the-art reviews of the key topics in glaciology and related disciplines in environmental change cutting-edge case studies of the latest research an interdisciplinary synthesis of the issues that draw together the research efforts of glaciologists and scientists from other areas such as geologists, hydrologists, and climatologists color-plate section (with selected extra figures provided in color at www.blackwellpublishing.com/knight). The topics in this book have been carefully chosen to reflect current priorities in research, the interdisciplinary nature of the subject, and the developing relationship between glaciology and studies of environmental change. Glacier Science and Environmental Change is essential reading for advanced undergraduates, postgraduate research students, and professional researchers in glaciology, geology, geography, geophysics, climatology, and related disciplines.
