The Gas Transfer Through Polar Sea Ice Experiment: Insights Into the Rates and Pathways that Determine Geochemical Fluxes PDF Download
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Author: Donald K. Perovich
Publisher:
ISBN:
Category : Arctic regions
Languages : en
Pages : 18
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Book Description
Sea ice is a defining feature of the polar marine environment. It is a critical domain for marine biota and it regulates ocean-atmosphere exchange, including the exchange of greenhouse gases such as CO2 and CH4. In this study, we determined the rates and pathways that govern gas transport through a mixed sea ice cover. N2O, SF6, 3He, 4He, and Ne were used as gas tracers of the exchange processes that take place at the ice-water and air-water interfaces in a laboratory sea ice experiment. Observation of the changes in gas concentrations during freezing revealed that He is indeed more soluble in ice than in water; Ne is less soluble in ice, and the larger gases (N2O and SF6) are mostly excluded during the freezing process. Model estimates of gas diffusion through ice were calibrated using measurements of bulk gas content in ice cores, yielding gas transfer velocity through ice (kice) of ∼5 × 10−4 m d−1. In comparison, the effective air-sea gas transfer velocities (keff) ranged up to 0.33 m d−1 providing further evidence that very little mixed-layer ventilation takes place via gas diffusion through columnar sea ice. However, this ventilation is distinct from air-ice gas fluxes driven by sea ice biogeochemistry. The magnitude of keff showed a clear increasing trend with wind speed and current velocity beneath the ice, as well as the combination of the two. This result indicates that gas transfer cannot be uniquely predicted by wind speed alone in the presence of sea ice.
Author: Donald K. Perovich
Publisher:
ISBN:
Category : Arctic regions
Languages : en
Pages : 18
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Book Description
Sea ice is a defining feature of the polar marine environment. It is a critical domain for marine biota and it regulates ocean-atmosphere exchange, including the exchange of greenhouse gases such as CO2 and CH4. In this study, we determined the rates and pathways that govern gas transport through a mixed sea ice cover. N2O, SF6, 3He, 4He, and Ne were used as gas tracers of the exchange processes that take place at the ice-water and air-water interfaces in a laboratory sea ice experiment. Observation of the changes in gas concentrations during freezing revealed that He is indeed more soluble in ice than in water; Ne is less soluble in ice, and the larger gases (N2O and SF6) are mostly excluded during the freezing process. Model estimates of gas diffusion through ice were calibrated using measurements of bulk gas content in ice cores, yielding gas transfer velocity through ice (kice) of ∼5 × 10−4 m d−1. In comparison, the effective air-sea gas transfer velocities (keff) ranged up to 0.33 m d−1 providing further evidence that very little mixed-layer ventilation takes place via gas diffusion through columnar sea ice. However, this ventilation is distinct from air-ice gas fluxes driven by sea ice biogeochemistry. The magnitude of keff showed a clear increasing trend with wind speed and current velocity beneath the ice, as well as the combination of the two. This result indicates that gas transfer cannot be uniquely predicted by wind speed alone in the presence of sea ice.
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309301866
Category : Science
Languages : en
Pages : 240
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Book Description
Once ice-bound, difficult to access, and largely ignored by the rest of the world, the Arctic is now front and center in the midst of many important questions facing the world today. Our daily weather, what we eat, and coastal flooding are all interconnected with the future of the Arctic. The year 2012 was an astounding year for Arctic change. The summer sea ice volume smashed previous records, losing approximately 75 percent of its value since 1980 and half of its areal coverage. Multiple records were also broken when 97 percent of Greenland's surface experienced melt conditions in 2012, the largest melt extent in the satellite era. Receding ice caps in Arctic Canada are now exposing land surfaces that have been continuously ice covered for more than 40,000 years. What happens in the Arctic has far-reaching implications around the world. Loss of snow and ice exacerbates climate change and is the largest contributor to expected global sea level rise during the next century. Ten percent of the world's fish catches comes from Arctic and sub-Arctic waters. The U.S. Geological Survey estimated that up to 13 percent of the world's remaining oil reserves are in the Arctic. The geologic history of the Arctic may hold vital clues about massive volcanic eruptions and the consequent release of massive amount of coal fly ash that is thought to have caused mass extinctions in the distant past. How will these changes affect the rest of Earth? What research should we invest in to best understand this previously hidden land, manage impacts of change on Arctic communities, and cooperate with researchers from other nations? The Arctic in the Anthropocene reviews research questions previously identified by Arctic researchers, and then highlights the new questions that have emerged in the wake of and expectation of further rapid Arctic change, as well as new capabilities to address them. This report is meant to guide future directions in U.S. Arctic research so that research is targeted on critical scientific and societal questions and conducted as effectively as possible. The Arctic in the Anthropocene identifies both a disciplinary and a cross-cutting research strategy for the next 10 to 20 years, and evaluates infrastructure needs and collaboration opportunities. The climate, biology, and society in the Arctic are changing in rapid, complex, and interactive ways. Understanding the Arctic system has never been more critical; thus, Arctic research has never been more important. This report will be a resource for institutions, funders, policy makers, and students. Written in an engaging style, The Arctic in the Anthropocene paints a picture of one of the last unknown places on this planet, and communicates the excitement and importance of the discoveries and challenges that lie ahead.
Author: Jens Bischof
Publisher: Springer Science & Business Media
ISBN: 9781852336486
Category : Nature
Languages : en
Pages : 254
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Book Description
The issue of global warming and climate change is of continuous concern. Since the 1970s, it bas been shown that the pack-ice around the Arctic Ocean is thinning, the margin of permafrost is moving north and the vegetation in the high northern parts of the world is changing (the 'greening' of the Arctic). But are these changes the result of human activity or simply regular variations of the Earth's climate system? Over thousands of years, a continuous archive of iceberg and sea ice drift bas formed in the deep-sea sediments, revealing the place of the ice's origin and allowing a reconstruction of the surface currents and the climate of the past. However, the drift of floating ice from one place to another is not just a passive record of past ocean circulation. It actively influences and changes the surface ocean circulation, thus having a profound effect on climate change. Ice Drift, Ocean Circulation and Climate Change is the first book to focus on the interactions between ice, the ocean and the atmosphere and to describe how these three components of the climate system influence each other. It makes clear the positive contribution of paleoclimatology and paleoceanography and should be read by anyone concerned with global warming and climate change.
Author: Emma Beer
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
The surface temperature in the Arctic has warmed at twice the rate of the global mean temperature during recent decades. This Arctic amplification of global warming has been a striking feature of climate change, and many studies have investigated what processes contribute to this phenomenon. Many of these processes are often described in the context of climate feedbacks using analyses focused on top-of-the-atmosphere radiative changes. In this context, regional surface warming can then be partitioned into contributions from each feedback process. However, this partitioning can be complicated by interactions between feedbacks themselves and atmospheric heat transport. In the second chapter, we instead apply a feedback-locking approach and evaluate the resulting changes in surface temperature. These results are strikingly different from previous feedback analyses, highlighting the important role of interactions within the climate system. This chapter and many other previous studies focus only on the role of atmospheric and surface processes in Arctic amplification. However, substantial questions remain regarding the role of ocean heat transport. In the third chapter, we investigate changes in oceanic heat fluxes under global warming. We find a mechanism associated with the presence of sea ice that drives enhanced horizontal ocean heat transport into the Arctic region and can contribute substantially to Arctic amplification if this heat is allowed to reach the surface. Currently, only a small amount of the heat stored at depth in the Arctic Ocean can reach the surface, but recent observational studies have argued that sea ice retreat could result in enhanced vertical mixing. In the fourth chapter, we investigate the impacts of a positive feedback whereby increased vertical mixing due to sea ice retreat causes the previously isolated subsurface Arctic Ocean heat to melt more sea ice. We find that an abrupt "tipping point" can occur under global warming, with an associated hysteresis window, for a limited range of parameters. Throughout the thesis, we use idealized models to show how ocean and climate processes can impact Arctic warming, providing insights into possible physical mechanisms that could be at play now or in the future.
Author: Intergovernmental Panel on Climate Change (IPCC)
Publisher: Cambridge University Press
ISBN: 9781009157971
Category : Science
Languages : en
Pages : 755
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Book Description
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.
Author: Kyle C. Armour
Publisher:
ISBN:
Category : Climatic changes
Languages : en
Pages : 114
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Book Description
We present work on several topics in physical climatology. Motivated by recent satellite observations of Arctic sea ice age, we investigate how the properties of first-year and multiyear ice regulate sea ice area and volume. Using an autoregressive model of sea ice and numerical simulation with a global dynamic-thermodynamic sea ice model that traces first-year and multiyear, we show that the sea ice mean state, variability, and sensitivity to forcing may be related to sea ice age. Ice age observations may thus offer insights into Arctic sea ice changes under warming. We next investigate the plausibility of sea ice threshold behavior and irreversible loss under global warming, a subject of much speculation following rapid sea ice declines in recent years. Within a state-of-the-art global climate model (GCM), carbon dioxide is increased until the oceans become ice-free and subsequently decreased until the ice cover returns. We find no evidence of irreversibility over the range of simulated sea ice conditions in the summer or winter ice cover in either hemisphere. We then shift our focus to quantification of the climate commitment---the warming that would still occur given no further emissions of greenhouse gases or aerosols. We show that elimination of emissions would cause global temperature to increase rapidly as aerosols are quickly washed from the atmosphere, and that large uncertainty in the present aerosol forcing implies large uncertainty in the climate commitment. The multi-millennial atmospheric lifetime of anthropogenic carbon dioxide causes global temperature to remain elevated for the indefinite future, making climate change from greenhouse gas emissions irreversible on human timescales. Finally, we propose a mechanism for the time-variation of global climate feedback as diagnosed within GCMs. Using a GCM and a low-order energy balance model, we show that the global climate feedback is fundamental related to the geographic patterns of regional feedbacks and surface warming. Its time-variation arises naturally when the pattern of surface warming evolves, activating regional feedbacks of different strengths. These findings have implications for our ability to constrain future climate changes from past and present observations, and for the quantification of climate sensitivity within models and observations.
Author: Adam Jerold Reed
Publisher: Frontiers Media SA
ISBN: 288966967X
Category : Science
Languages : en
Pages : 149
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Book Description
Author: National Academies of Sciences, Engineering, and Medicine
Publisher: National Academies Press
ISBN: 0309456002
Category : Science
Languages : en
Pages : 83
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Book Description
The sea ice surrounding Antarctica has increased in extent and concentration from the late 1970s, when satellite-based measurements began, until 2015. Although this increasing trend is modest, it is surprising given the overall warming of the global climate and the region. Indeed, climate models, which incorporate our best understanding of the processes affecting the region, generally simulate a decrease in sea ice. Moreover, sea ice in the Arctic has exhibited pronounced declines over the same period, consistent with global climate model simulations. For these reasons, the behavior of Antarctic sea ice has presented a conundrum for global climate change science. The National Academies of Sciences, Engineering, and Medicine held a workshop in January 2016, to bring together scientists with different sets of expertise and perspectives to further explore potential mechanisms driving the evolution of recent Antarctic sea ice variability and to discuss ways to advance understanding of Antarctic sea ice and its relationship to the broader ocean-climate system. This publication summarizes the presentations and discussions from the workshop.
Author: Peter S. Liss
Publisher: Springer
ISBN: 3642256430
Category : Science
Languages : en
Pages : 315
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Book Description
The oceans and atmosphere interact through various processes, including the transfer of momentum, heat, gases and particles. In this book leading international experts come together to provide a state-of-the-art account of these exchanges and their role in the Earth-system, with particular focus on gases and particles. Chapters in the book cover: i) the ocean-atmosphere exchange of short-lived trace gases; ii) mechanisms and models of interfacial exchange (including transfer velocity parameterisations); iii) ocean-atmosphere exchange of the greenhouse gases carbon dioxide, methane and nitrous oxide; iv) ocean atmosphere exchange of particles and v) current and future data collection and synthesis efforts. The scope of the book extends to the biogeochemical responses to emitted / deposited material and interactions and feedbacks in the wider Earth-system context. This work constitutes a highly detailed synthesis and reference; of interest to higher-level university students (Masters, PhD) and researchers in ocean-atmosphere interactions and related fields (Earth-system science, marine / atmospheric biogeochemistry / climate). Production of this book was supported and funded by the EU COST Action 735 and coordinated by the International SOLAS (Surface Ocean- Lower Atmosphere Study) project office.
Author: David N. Thomas
Publisher: John Wiley & Sons
ISBN: 1118778383
Category : Science
Languages : en
Pages : 666
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Book Description
Over the past 20 years the study of the frozen Arctic and Southern Oceans and sub-arctic seas has progressed at a remarkable pace. This third edition of Sea Ice gives insight into the very latest understanding of the how sea ice is formed, how we measure (and model) its extent, the biology that lives within and associated with sea ice and the effect of climate change on its distribution. How sea ice influences the oceanography of underlying waters and the influences that sea ice has on humans living in Arctic regions are also discussed. Featuring twelve new chapters, this edition follows two previous editions (2001 and 2010), and the need for this latest update exhibits just how rapidly the science of sea ice is developing. The 27 chapters are written by a team of more than 50 of the worlds’ leading experts in their fields. These combine to make the book the most comprehensive introduction to the physics, chemistry, biology and geology of sea ice that there is. This third edition of Sea Ice will be a key resource for all policy makers, researchers and students who work with the frozen oceans and seas.
