Antarctic Sea Ice Extent Reconstructions Throughout the 20th Century PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Antarctic Sea Ice Extent Reconstructions Throughout the 20th Century PDF full book. Access full book title Antarctic Sea Ice Extent Reconstructions Throughout the 20th Century by Amanda M. Sleinkofer. Download full books in PDF and EPUB format.
Author: Amanda M. Sleinkofer Publisher: ISBN: Category : Climatic changes Languages : en Pages : 218
Book Description
Due to the global impacts of Antarctic sea ice and the changing climate, it is important to understand what is influencing Antarctic sea ice variability in a historical context. This is especially true since observations of Antarctic sea ice only begin around 1979. To investigate what is influencing Antarctic sea ice in a longer context, this study generated, evaluated, and analyzed new reconstructions of Antarctic sea ice extent (SIE) through statistical relationships with other long-term datasets available throughout the 20th century. A principal component regression technique that has been proven successful in other Antarctic climate reconstructions was employed in this study, using pressure and temperature observations across the Southern Hemisphere in conjunction with indices of large-scale climate variability known to influence Antarctic SIE. Ultimately, this study was conducted to determine if Antarctic SIE reconstructions are a skillful measure for understanding historical Antarctic sea ice trends and variability throughout the 20th century. The newly generated reconstructions demonstrate that skillful seasonal (extending back to 1905) and monthly (extending back to 1957) sea ice reconstructions can be produced. In comparison, the monthly reconstructions outperformed the seasonal reconstructions based on various assessments (including an independent validation approach), although both sets of reconstructions improved historical sea ice extent knowledge well beyond the use climatological mean. Although shorter in duration due to the inclusion of nearby Antarctic temperature and pressure (which begin near 1957), the monthly reconstructions also allowed for a broader analysis on sea ice extent for month-to-month variations and were useful for monitoring changes in the reconstruction skill performance that could not be seen on a seasonal level. While these new reconstructions unlock new information previously unknown about early 20th century Antarctic sea ice extent, one of the more scientifically important revelations from the new reconstructions were changes in temporal trends throughout the 20th century. Specifically, this study found that half of the reconstructions had a sign switch in the sea ice extent trends between the pre-satellite era (before 1979) and the observed satellite era (after 1979), highlighting the importance of temporal variability in the short observational sea ice record that was only hinted at in the short observational record. Overall, given their skill and connection to many physical processes, the new reconstructions will allow for an increase in the broad scale understanding of Antarctic climate variability over a much longer period than presently afforded by observations alone.
Author: Amanda M. Sleinkofer Publisher: ISBN: Category : Climatic changes Languages : en Pages : 218
Book Description
Due to the global impacts of Antarctic sea ice and the changing climate, it is important to understand what is influencing Antarctic sea ice variability in a historical context. This is especially true since observations of Antarctic sea ice only begin around 1979. To investigate what is influencing Antarctic sea ice in a longer context, this study generated, evaluated, and analyzed new reconstructions of Antarctic sea ice extent (SIE) through statistical relationships with other long-term datasets available throughout the 20th century. A principal component regression technique that has been proven successful in other Antarctic climate reconstructions was employed in this study, using pressure and temperature observations across the Southern Hemisphere in conjunction with indices of large-scale climate variability known to influence Antarctic SIE. Ultimately, this study was conducted to determine if Antarctic SIE reconstructions are a skillful measure for understanding historical Antarctic sea ice trends and variability throughout the 20th century. The newly generated reconstructions demonstrate that skillful seasonal (extending back to 1905) and monthly (extending back to 1957) sea ice reconstructions can be produced. In comparison, the monthly reconstructions outperformed the seasonal reconstructions based on various assessments (including an independent validation approach), although both sets of reconstructions improved historical sea ice extent knowledge well beyond the use climatological mean. Although shorter in duration due to the inclusion of nearby Antarctic temperature and pressure (which begin near 1957), the monthly reconstructions also allowed for a broader analysis on sea ice extent for month-to-month variations and were useful for monitoring changes in the reconstruction skill performance that could not be seen on a seasonal level. While these new reconstructions unlock new information previously unknown about early 20th century Antarctic sea ice extent, one of the more scientifically important revelations from the new reconstructions were changes in temporal trends throughout the 20th century. Specifically, this study found that half of the reconstructions had a sign switch in the sea ice extent trends between the pre-satellite era (before 1979) and the observed satellite era (after 1979), highlighting the importance of temporal variability in the short observational sea ice record that was only hinted at in the short observational record. Overall, given their skill and connection to many physical processes, the new reconstructions will allow for an increase in the broad scale understanding of Antarctic climate variability over a much longer period than presently afforded by observations alone.
Author: Nicholas Beaty Publisher: ISBN: Category : Albedo Languages : en Pages : 0
Book Description
Ongoing changes in the Earth's cryosphere create positive feedback loops through changing albedo, creating a spark of interest in researchers on what is happening in regions of sea ice. Despite this conviction for research, Antarctic sea ice observations have been sparsely recorded throughout human history and have only been reliably observed since the introduction of satellite measurements in approximately 1979. Recent research has shown the ability to reconstruct Antarctic pressure and sea ice extent values throughout two different studies using principal component regression techniques based primarily on temperature and pressure observations along with large-scale climate variability indices that influences Antarctic sea ice. This short historical span of sea ice concentration (SIC), a pixel-scale observation that outlines how much of the ocean area is covered in sea ice, have shown increases around much of Antarctica since 1979. This short historical record, comparatively, does not capture the full range of climate variability in one of the most isolated places on Earth. To improve the understanding of historical variations in Antarctic SIC, reconstructions of the five leading empirical orthogonal functions (EOF) have been conducted in this study to extend SIC data back to 1905. This new seasonally resolved dataset allows researchers to place current trends in a longer historical context. This study examines the skill of these seasonal Antarctic SIC reconstructions, the first of their kind, along with discussing regional changes in Antarctic sea ice since the beginning of the 20th century, and the implications these historical variations may have for further Antarctic sea ice and future research. The resultant reconstructions of SIC presented through this study outline the ability to gather skillful and meaningful results on seasonal scales through 1905 that provide overall much better skill than the climatological mean. These reconstructions allowed for analysis on sea ice concentration trends throughout the pre-satellite era spatially and temporally to understand the overall trends of Antarctic sea ice in a longer historical context than ever before, supporting previous regime changes in sea ice patterns between the pre-satellite era and observed satellite era (after 1979) suggested in previous work. In particular, the role of Pacific Ocean variability in Antarctic SIC throughout the 20th century is made even more prominent through investigating the importance of predictor networks and correlations of modes of climate variability with SIC in this study.
Author: Riley L. McCreary Publisher: ISBN: Category : Antarctica Languages : en Pages : 0
Book Description
Changes in Earth's cryosphere, including sea ice in both polar regions, often result in amplified climate-related impacts through positive feedback loops, making it crucial to understand how and why the cryosphere is evolving now and into the future. Observations of Antarctic sea ice are comparably short as the records have only been reliably observed since the satellite era began in 1979. Prior to the satellite era, limited data sources on Antarctic sea ice are available, including various reconstructions and discrete information in ship logbooks from expeditions and commercial vessels written in the remarks sections. This research aims to further understand how independent early sources of information can be used to evaluate the skill of seasonal Antarctic sea ice extent reconstructions (Fogt et al. 2022). Ship logbook observations of sea ice are extremely valuable because they are able to give insight into where the ice edge was prior to satellite measurement in 1979. As this is a new area of research, little is yet known on what potential data have been recovered. Not only is it important to know what data are available, but also if the ship logbooks are reliable enough to be used to evaluate Antarctic sea ice extent reconstructions. This research compiled a list of available ship logbooks at Ohio University, only a handful of which were able to be digitized in time for this project. The latitudes from the ship logbooks of the ice edge show to be within an acceptable range of the latitudes of the sea ice from reconstructions (on average within 3°), indicating the skill of the sea ice extent reconstructions, spatially and temporally, is good prior to 1979. The Antarctic sea ice extent reconstructions were also compared with estimates of early twentieth century sea ice extent from coupled climate models in terms of the ranges of variability and linear trends. Overall, the variability in the sea ice, both temporally and spatially, are similar between the coupled climate models and the reconstructions, suggesting the statistically generated reconstructions are able to produce physically plausible variations contained in the climate models. The linear trends, especially in the early twentieth century, are similar between the coupled climate models and the reconstructions, even though the end of the twentieth century in the models is showing a decreasing trend in sea ice and the reconstructions have a positive trend.
Author: Thomas Johannes Maierhofer Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
The short satellite-observed period from 1979 to 2023 has seen the Antarctic sea ice changedramatically. The sea ice generally increased until 2014 then precipitously decreased from 2014 to 2017. Record lows were then observed in February 2022 and February 2023. To evaluate these recent changes in the context of anthropogenic climate change requires information on Antarctic sea ice variability over the full 20th century. However, only temporally and spatially sparse data are available before 1979, creating a need for statistical reconstructions. We create a stochastic ensemble reconstruction of monthly Antarctic sea ice extent from 1900-1979 using a novel Bayesian spatio-temporal model. This model produces a set of 2500 plausible reconstructions of sea ice extent by sector. These reconstructions improve on prior approaches with realistic month-to-month changes and interdecadal trends as well as plausible interactions between the sectors. These unique features allow the direct computation of extreme event probabilities for the pre-satellite period of the 20th century. For example, we compute a 0.44% probability of reconstructing a decline in total Antarctic sea ice extent as extreme or more extreme than the 2014-2017 decline. We compute a 16% probability of observing a sea ice minimum as low or lower than the February 2022 minimum in total sea ice extent of 2.22 mio. km2, and a probability of 4% for the February 2023 minimum of 2.04 mio. km2. We also propose a novel approach to modeling the Antarctic sea ice edge using a functional regression model. The sea ice edge on a given day is treated as a continuous set of points circling the South Pole and the latitudes of these points are modeled as a function of their longitude. This enables the estimation and visualization of a circumpolar annual cycle and interannual development of the sea ice, providing novel insight into the regionality of sea ice variability. We develop statistical techniques for reconstructing 1966-1978 Antarctic sea ice extent using early satellite images in the visible and infrared spectrum. These images have not previously been analyzed due to severe missingness and cloud cover occluding the sea ice. Combining extensive preprocessing with modern statistical methods, we produce monthly sea ice concentration maps from which we compute historic sea ice extent.
Author: Beatrice K. Waters Publisher: ISBN: Category : Antarctica Languages : en Pages : 0
Book Description
As climate change continues unabated, understanding Earth’s complex climate system remains critical. The Antarctic climate system is a crucial part of this system, and the sea ice surrounding the continent is an incredibly important element. With the largest change in albedo on Earth, Antarctic sea ice is responsible for reflecting solar radiation from the region. As seen in the Arctic as a result of climate change, without sea ice this solar radiation is absorbed by the low albedo ocean causing warming and further melt of sea ice in a positive feedback loop. Antarctic sea has not responded in the same way as the Arctic. Observations of Antarctic sea ice date back to October 1978 and have shown an overall increase in sea ice. A sudden decline in sea ice extent in 2016 was an unexpected turn of events, and a new record low extent in February 2023 has further complicated this. Due to the short records of Antarctic sea ice extent and the complex nature of the regional climate system, it is difficult to isolate the impacts of climate change in the region. To expand these short records, reconstructions have been utilized. Monthly reconstructions, based on observational temperature and pressure data, were created in order to extend this record to 1957. These reconstructions were analyzed in this study in order to determine their skill and understand how Antarctic sea ice extent has changed through the 1957-2020 period. This was done for the total sea ice extent around the Antarctic continent as well as the Bellingshausen-Amundsen, East Antarctic, King Hakon, Ross, and Weddell regions. The reconstructions were analyzed using correlation, regression, and comparison of means statistical methods in order to evaluate relationships between Antarctic climate data and sea ice extent, relationships between modes of climate variability and sea ice extent, changes in the seasonal cycle of sea ice extent, and trends in sea ice extent. It was of interest to determine if there were changes between the early 1957-1978 period and the 1979-2020 observational period, as this is a likely indicator of reconstruction performance. It was found that the monthly reconstructions generally have a high level of skill. Relationships between sea ice extent and Antarctic climate data and between sea ice extent and climate modes of variability were typically maintained. Specifically, the dipole relationship (increasing versus decreasing sea ice extent) between the Bellingshausen-Amundsen and Ross regions was demonstrated in the relationships analyzed in this study. Analysis of the seasonal cycle revealed changes through time, including statistically significant changes in annual sea ice growth for the total extent, Ross, King Hakon, and Weddell regions. Trend analysis suggests that the monthly reconstructions may capture the mid-century regime shift in sea ice extent found in Fogt et al. (2022), although this is not true for all sectors, specifically Ross. Correlations between these seasonal reconstructions and the monthly reconstructions analyzed in this study were highly variable and more analysis is needed to determine the cause. This study provides a crucial initial analysis of previously unanalyzed monthly SIE reconstructions. Extending the SIE record is a critically important part of understanding the future of Antarctic climate.
Author: National Academies of Sciences, Engineering, and Medicine Publisher: National Academies Press ISBN: 0309456002 Category : Science Languages : en Pages : 83
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: National Research Council Publisher: National Academies Press ISBN: 0309102251 Category : Science Languages : en Pages : 160
Book Description
In response to a request from Congress, Surface Temperature Reconstructions for the Last 2,000 Years assesses the state of scientific efforts to reconstruct surface temperature records for Earth during approximately the last 2,000 years and the implications of these efforts for our understanding of global climate change. Because widespread, reliable temperature records are available only for the last 150 years, scientists estimate temperatures in the more distant past by analyzing "proxy evidence," which includes tree rings, corals, ocean and lake sediments, cave deposits, ice cores, boreholes, and glaciers. Starting in the late 1990s, scientists began using sophisticated methods to combine proxy evidence from many different locations in an effort to estimate surface temperature changes during the last few hundred to few thousand years. This book is an important resource in helping to understand the intricacies of global climate change.
Author: David N. Thomas Publisher: John Wiley & Sons ISBN: 1118778383 Category : Science Languages : en Pages : 666
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.
Author: National Academies of Sciences, Engineering, and Medicine Publisher: National Academies Press ISBN: 0309456037 Category : Science Languages : en Pages : 83
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: Amanda M. Sleinkofer
Author: Amanda M. Sleinkofer
Author: Nicholas Beaty
Author: Riley L. McCreary
Author: Thomas Johannes Maierhofer
Author: Beatrice K. Waters
Author: National Academies of Sciences, Engineering, and Medicine
Author: National Research Council
Author: David N. Thomas
Author: National Academies of Sciences, Engineering, and Medicine
Author: Simona Masina