Pub Date : 2021-01-04DOI: 10.1146/annurev-earth-072020-055249
C. Ostrander, Aleisha C. Johnson, A. Anbar
The rise of molecular oxygen (O2) in the atmosphere and oceans was one of the most consequential changes in Earth's history. While most research focuses on the Great Oxidation Event (GOE) near the ...
{"title":"Earth's First Redox Revolution","authors":"C. Ostrander, Aleisha C. Johnson, A. Anbar","doi":"10.1146/annurev-earth-072020-055249","DOIUrl":"https://doi.org/10.1146/annurev-earth-072020-055249","url":null,"abstract":"The rise of molecular oxygen (O2) in the atmosphere and oceans was one of the most consequential changes in Earth's history. While most research focuses on the Great Oxidation Event (GOE) near the ...","PeriodicalId":8034,"journal":{"name":"Annual Review of Earth and Planetary Sciences","volume":null,"pages":null},"PeriodicalIF":14.9,"publicationDate":"2021-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75303352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-21DOI: 10.1146/annurev-earth-081420-063858
Y. Axford, A. Vernal, E. Osterberg
Higher boreal summer insolation in the early to middle Holocene drove thousands of years of summer warming across the Arctic. Modern-day warming has distinctly different causes, but geologic data from this past warm period hold lessons for the future. We compile Holocene temperature reconstructions from ice, lake, and marine cores around Greenland, where summer temperatures are globally important due to their influence on ice sheet mass balance, ocean circulation, and sea ice. Highlighting and accounting for some key issues with proxy interpretation, we find that much of Greenland experienced summers 3 to 5°C warmer than the mid-twentieth century in the early Holocene—earlier and stronger warming than often presumed. Warmth had dramatic consequences: Many glaciers disappeared, perennial sea ice retreated, plants and animals migrated northward, the Greenland Ice Sheet shrank rapidly, and increased meltwater discharge led to strong marine water stratification and enhanced winter sea ice in some areas. ▪ Summer air temperatures and open ocean temperatures around much of Greenland peaked in the early Holocene in response to elevated summer insolation. ▪ Peak summer air temperatures ranged from 3 to 5°C warmer than the mid-twentieth century in northwest and central Greenland to perhaps 1 to 2°C in south Greenland. ▪ Many differences between records can be explained by proxy seasonality, ice sheet elevation changes, vegetation analogs and lags, and the nearshore effects of ice sheet meltwater. ▪ Early Holocene warmth dramatically affected glaciers and the Greenland Ice Sheet; meltwater discharge, nearshore ocean salinity, and sea ice; and diverse flora and fauna. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 49 is May 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
{"title":"Past Warmth and Its Impacts During the Holocene Thermal Maximum in Greenland","authors":"Y. Axford, A. Vernal, E. Osterberg","doi":"10.1146/annurev-earth-081420-063858","DOIUrl":"https://doi.org/10.1146/annurev-earth-081420-063858","url":null,"abstract":"Higher boreal summer insolation in the early to middle Holocene drove thousands of years of summer warming across the Arctic. Modern-day warming has distinctly different causes, but geologic data from this past warm period hold lessons for the future. We compile Holocene temperature reconstructions from ice, lake, and marine cores around Greenland, where summer temperatures are globally important due to their influence on ice sheet mass balance, ocean circulation, and sea ice. Highlighting and accounting for some key issues with proxy interpretation, we find that much of Greenland experienced summers 3 to 5°C warmer than the mid-twentieth century in the early Holocene—earlier and stronger warming than often presumed. Warmth had dramatic consequences: Many glaciers disappeared, perennial sea ice retreated, plants and animals migrated northward, the Greenland Ice Sheet shrank rapidly, and increased meltwater discharge led to strong marine water stratification and enhanced winter sea ice in some areas. ▪ Summer air temperatures and open ocean temperatures around much of Greenland peaked in the early Holocene in response to elevated summer insolation. ▪ Peak summer air temperatures ranged from 3 to 5°C warmer than the mid-twentieth century in northwest and central Greenland to perhaps 1 to 2°C in south Greenland. ▪ Many differences between records can be explained by proxy seasonality, ice sheet elevation changes, vegetation analogs and lags, and the nearshore effects of ice sheet meltwater. ▪ Early Holocene warmth dramatically affected glaciers and the Greenland Ice Sheet; meltwater discharge, nearshore ocean salinity, and sea ice; and diverse flora and fauna. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 49 is May 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.","PeriodicalId":8034,"journal":{"name":"Annual Review of Earth and Planetary Sciences","volume":null,"pages":null},"PeriodicalIF":14.9,"publicationDate":"2020-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88471373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-18DOI: 10.1146/annurev-earth-080320-062509
E. Ohtani
Hydrogen and deuterium isotopic evidence indicates that the source of terrestrial water was mostly meteorites, with additional influx from nebula gas during accretion. There are two Earth models, with large (7–12 ocean masses) and small (1–4 ocean masses) water budgets that can explain the geochemical, cosmochemical, and geological observations. Geophysical and mineral physics data indicate that the upper and lower mantles are generally dry, whereas the mantle transition zone is wetter, with heterogeneous water distribution. Subducting slabs are a source of water influx, and there are three major sites of deep dehydration: the base of the upper mantle, and the top and bottom of the lower mantle in addition to slabs in the shallow upper mantle. Hydrated regions surround these dehydration sites. The core may be a hidden reservoir of hydrogen under the large water budget model. ▪ Earth is a water planet. Where and when was water delivered, and how much? How does water circulate in Earth? This review looks at the current answers to these fundamental questions. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 49 is May 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
{"title":"Hydration and Dehydration in Earth's Interior","authors":"E. Ohtani","doi":"10.1146/annurev-earth-080320-062509","DOIUrl":"https://doi.org/10.1146/annurev-earth-080320-062509","url":null,"abstract":"Hydrogen and deuterium isotopic evidence indicates that the source of terrestrial water was mostly meteorites, with additional influx from nebula gas during accretion. There are two Earth models, with large (7–12 ocean masses) and small (1–4 ocean masses) water budgets that can explain the geochemical, cosmochemical, and geological observations. Geophysical and mineral physics data indicate that the upper and lower mantles are generally dry, whereas the mantle transition zone is wetter, with heterogeneous water distribution. Subducting slabs are a source of water influx, and there are three major sites of deep dehydration: the base of the upper mantle, and the top and bottom of the lower mantle in addition to slabs in the shallow upper mantle. Hydrated regions surround these dehydration sites. The core may be a hidden reservoir of hydrogen under the large water budget model. ▪ Earth is a water planet. Where and when was water delivered, and how much? How does water circulate in Earth? This review looks at the current answers to these fundamental questions. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 49 is May 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.","PeriodicalId":8034,"journal":{"name":"Annual Review of Earth and Planetary Sciences","volume":null,"pages":null},"PeriodicalIF":14.9,"publicationDate":"2020-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82034214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-30DOI: 10.1146/annurev-earth-072519-055956
I. Fung
The atmosphere is the synthesizer, transformer, and communicator of exchanges at its boundaries with the land and oceans. These exchanges depend on and, in turn, alter the states of the atmosphere, land, and oceans themselves. To a large extent, the interactions between the carbon cycle and climate have mapped, and will map, the trajectory of the Earth system. My quest to understand climate dynamics and the global carbon cycle has been propelled by new puzzles that emerge from each of the investigations and has led me to study subdisciplines of Earth science beyond my formal training. This article sketches my trek and the lessons I have learned. ▪ About half the CO2 emitted from combustion of fossil fuels and from cement production has remained airborne. Where are the contemporary carbon sinks? To what degree will these sinks evolve with, and in turn accelerate, climate change itself? ▪ The pursuit of these questions has been propelled by the integration of in situ and satellite observations of the atmosphere, land, and oceans, as well as by advances in theory and coupled climate–carbon cycle modeling. ▪ The urgency of climate change demands new approaches to cross-check national emission statistics.
{"title":"In Pursuit","authors":"I. Fung","doi":"10.1146/annurev-earth-072519-055956","DOIUrl":"https://doi.org/10.1146/annurev-earth-072519-055956","url":null,"abstract":"The atmosphere is the synthesizer, transformer, and communicator of exchanges at its boundaries with the land and oceans. These exchanges depend on and, in turn, alter the states of the atmosphere, land, and oceans themselves. To a large extent, the interactions between the carbon cycle and climate have mapped, and will map, the trajectory of the Earth system. My quest to understand climate dynamics and the global carbon cycle has been propelled by new puzzles that emerge from each of the investigations and has led me to study subdisciplines of Earth science beyond my formal training. This article sketches my trek and the lessons I have learned. ▪ About half the CO2 emitted from combustion of fossil fuels and from cement production has remained airborne. Where are the contemporary carbon sinks? To what degree will these sinks evolve with, and in turn accelerate, climate change itself? ▪ The pursuit of these questions has been propelled by the integration of in situ and satellite observations of the atmosphere, land, and oceans, as well as by advances in theory and coupled climate–carbon cycle modeling. ▪ The urgency of climate change demands new approaches to cross-check national emission statistics.","PeriodicalId":8034,"journal":{"name":"Annual Review of Earth and Planetary Sciences","volume":null,"pages":null},"PeriodicalIF":14.9,"publicationDate":"2020-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84058505","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-29DOI: 10.1146/annurev-earth-071719-054845
Tatsuhiko Saito, T. Kubota
This article reviews tsunami modeling and its relation to recent developments of deep-ocean observations. Unlike near-coast observations, deep-ocean observations have enabled the capture of short-w...
本文综述了海啸模拟及其与深海观测的最新进展的关系。与近岸观测不同的是，深海观测能够捕捉到短w…
{"title":"Tsunami Modeling for the Deep Sea and Inside Focal Areas","authors":"Tatsuhiko Saito, T. Kubota","doi":"10.1146/annurev-earth-071719-054845","DOIUrl":"https://doi.org/10.1146/annurev-earth-071719-054845","url":null,"abstract":"This article reviews tsunami modeling and its relation to recent developments of deep-ocean observations. Unlike near-coast observations, deep-ocean observations have enabled the capture of short-w...","PeriodicalId":8034,"journal":{"name":"Annual Review of Earth and Planetary Sciences","volume":null,"pages":null},"PeriodicalIF":14.9,"publicationDate":"2020-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82194520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-29DOI: 10.1146/annurev-earth-071719-054827
S. Holland
Interpretations of the tempo of mass extinctions and recoveries often rely on the distribution of fossils in a stratigraphic column. These interpretations are generally compromised when they are not based on a knowledge of marine ecological gradients and sequence-stratigraphic architecture. Crucially, last and first occurrences of species do not record times of extinction and origination. A face-value interpretation of the stratigraphic record leads to incorrect inferences of pulsed extinction, underestimates of the duration of mass extinction, and overestimates of local recovery times. An understanding of the processes of extinction and recovery is substantially improved by knowledge of the distribution of species along marine environmental gradients, interpreting sequence-stratigraphic architecture to show how those gradients are sampled through time, and sampling along regional transects along depositional dip. Doing so suggests that most ancient mass extinctions were substantially longer and local recoveries substantially shorter than generally thought. ▪ The concepts that let geologists find petroleum allow paleontologists to reinterpret ancient mass extinctions and their recoveries. ▪ Most ancient mass extinctions were longer than the fossil record suggests, lasting hundreds of thousands of years to a few million years. ▪ Ancient recoveries from mass extinctions were shorter than thought and likely overlapped with extinction during a period of turnover.
{"title":"The Stratigraphy of Mass Extinctions and Recoveries","authors":"S. Holland","doi":"10.1146/annurev-earth-071719-054827","DOIUrl":"https://doi.org/10.1146/annurev-earth-071719-054827","url":null,"abstract":"Interpretations of the tempo of mass extinctions and recoveries often rely on the distribution of fossils in a stratigraphic column. These interpretations are generally compromised when they are not based on a knowledge of marine ecological gradients and sequence-stratigraphic architecture. Crucially, last and first occurrences of species do not record times of extinction and origination. A face-value interpretation of the stratigraphic record leads to incorrect inferences of pulsed extinction, underestimates of the duration of mass extinction, and overestimates of local recovery times. An understanding of the processes of extinction and recovery is substantially improved by knowledge of the distribution of species along marine environmental gradients, interpreting sequence-stratigraphic architecture to show how those gradients are sampled through time, and sampling along regional transects along depositional dip. Doing so suggests that most ancient mass extinctions were substantially longer and local recoveries substantially shorter than generally thought. ▪ The concepts that let geologists find petroleum allow paleontologists to reinterpret ancient mass extinctions and their recoveries. ▪ Most ancient mass extinctions were longer than the fossil record suggests, lasting hundreds of thousands of years to a few million years. ▪ Ancient recoveries from mass extinctions were shorter than thought and likely overlapped with extinction during a period of turnover.","PeriodicalId":8034,"journal":{"name":"Annual Review of Earth and Planetary Sciences","volume":null,"pages":null},"PeriodicalIF":14.9,"publicationDate":"2020-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88420563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-29DOI: 10.1146/annurev-earth-053018-060428
Safa Mote, Jorge Rivas, E. Kalnay
The Human System is within the Earth System. They should be modeled bidirectionally coupled, as they are in reality. The Human System is rapidly expanding, mostly due to consumption of fossil fuels (approximately one million times faster than Nature accumulated them) and fossil water. This threatens not only other planetary subsystems but also the Human System itself. Carrying Capacity is an important tool to measure sustainability, but there is a widespread view that Carrying Capacity is not applicable to humans. Carrying Capacity has generally been prescribed a priori, mostly using the logistic equation. However, the real dynamics of human population and consumption are not represented by this equation or its variants. We argue that Carrying Capacity should not be prescribed but should insteadbe dynamically derived a posteriori from the bidirectional coupling of Earth System submodels with the Human System model. We demonstrate this approach with a minimal model of Human–Nature interaction (HANDY). ▪ The Human System is a subsystem of the Earth System, with inputs (resources) from Earth System sources and outputs (waste, emissions) to Earth System sinks. ▪ The Human System is growing rapidly due to nonrenewable stocks of fossil fuels and water and threatens the sustainability of the Human System and to overwhelm the Earth System. ▪ Carrying Capacity has been prescribed a priori and using the logistic equation, which does not represent the dynamics of the Human System. ▪ Our new approach to human Carrying Capacity is derived from dynamically coupled Earth System–Human System models and can be used to estimate the sustainability of the Human System.
{"title":"A Novel Approach to Carrying Capacity: From a priori Prescription to a posteriori Derivation Based on Underlying Mechanisms and Dynamics","authors":"Safa Mote, Jorge Rivas, E. Kalnay","doi":"10.1146/annurev-earth-053018-060428","DOIUrl":"https://doi.org/10.1146/annurev-earth-053018-060428","url":null,"abstract":"The Human System is within the Earth System. They should be modeled bidirectionally coupled, as they are in reality. The Human System is rapidly expanding, mostly due to consumption of fossil fuels (approximately one million times faster than Nature accumulated them) and fossil water. This threatens not only other planetary subsystems but also the Human System itself. Carrying Capacity is an important tool to measure sustainability, but there is a widespread view that Carrying Capacity is not applicable to humans. Carrying Capacity has generally been prescribed a priori, mostly using the logistic equation. However, the real dynamics of human population and consumption are not represented by this equation or its variants. We argue that Carrying Capacity should not be prescribed but should insteadbe dynamically derived a posteriori from the bidirectional coupling of Earth System submodels with the Human System model. We demonstrate this approach with a minimal model of Human–Nature interaction (HANDY). ▪ The Human System is a subsystem of the Earth System, with inputs (resources) from Earth System sources and outputs (waste, emissions) to Earth System sinks. ▪ The Human System is growing rapidly due to nonrenewable stocks of fossil fuels and water and threatens the sustainability of the Human System and to overwhelm the Earth System. ▪ Carrying Capacity has been prescribed a priori and using the logistic equation, which does not represent the dynamics of the Human System. ▪ Our new approach to human Carrying Capacity is derived from dynamically coupled Earth System–Human System models and can be used to estimate the sustainability of the Human System.","PeriodicalId":8034,"journal":{"name":"Annual Review of Earth and Planetary Sciences","volume":null,"pages":null},"PeriodicalIF":14.9,"publicationDate":"2020-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83343175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-29DOI: 10.1146/annurev-earth-073019-045641
J. Vinther
Melanin and other pigments are now well known to be important in exceptional preservation of soft tissues in vertebrates and other animals. Because pigments confer coloration and even structural colors, they have opened a new field of paleocolor reconstruction. Since its inception about a decade ago, reconstruction of color patterns has been performed on several vertebrates, including feathered and scale-clad dinosaurs. Iridescence and other types of structural color can also be identified through melanosome shape and arrangement. How pigments and melanosomes fossilize and are altered has become an important research subject. Ancient color patterns that may range from crypsis to brilliant displays have revealed insights into the evolution and escalation of visual systems, the nature of ancient animal interactions, and how several unique characteristics of birds already arose among dinosaurs. ▪ Melanin and other pigments preserve in exceptional fossils; this opens paths for reconstructing coloration of extinct organisms, such as dinosaurs. ▪ The most abundant pigment is melanin, which can be identified chemically and through preserved melanosome microbodies. ▪ Melanosome shape reveals clues to original hue ranging from reddish brown and black to gray and structural coloration. ▪ Other pigments may preserve, such as porphyrin pigments in theropod dinosaur eggshells. ▪ Fossil color patterns contribute new insights into the evolution of visual systems, predator-prey interactions, and key innovations.
{"title":"Reconstructing Vertebrate Paleocolor","authors":"J. Vinther","doi":"10.1146/annurev-earth-073019-045641","DOIUrl":"https://doi.org/10.1146/annurev-earth-073019-045641","url":null,"abstract":"Melanin and other pigments are now well known to be important in exceptional preservation of soft tissues in vertebrates and other animals. Because pigments confer coloration and even structural colors, they have opened a new field of paleocolor reconstruction. Since its inception about a decade ago, reconstruction of color patterns has been performed on several vertebrates, including feathered and scale-clad dinosaurs. Iridescence and other types of structural color can also be identified through melanosome shape and arrangement. How pigments and melanosomes fossilize and are altered has become an important research subject. Ancient color patterns that may range from crypsis to brilliant displays have revealed insights into the evolution and escalation of visual systems, the nature of ancient animal interactions, and how several unique characteristics of birds already arose among dinosaurs. ▪ Melanin and other pigments preserve in exceptional fossils; this opens paths for reconstructing coloration of extinct organisms, such as dinosaurs. ▪ The most abundant pigment is melanin, which can be identified chemically and through preserved melanosome microbodies. ▪ Melanosome shape reveals clues to original hue ranging from reddish brown and black to gray and structural coloration. ▪ Other pigments may preserve, such as porphyrin pigments in theropod dinosaur eggshells. ▪ Fossil color patterns contribute new insights into the evolution of visual systems, predator-prey interactions, and key innovations.","PeriodicalId":8034,"journal":{"name":"Annual Review of Earth and Planetary Sciences","volume":null,"pages":null},"PeriodicalIF":14.9,"publicationDate":"2020-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85390297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-29DOI: 10.1146/annurev-earth-081619-052609
G. Balco
Surface exposure dating using cosmic-ray-produced nuclides has been applied to determine the age of thousands of landforms produced by alpine glaciers in mountain areas worldwide. These data are potentially an extensive, easily accessible, and globally distributed paleoclimate record. In particular, exposure-dated glacier chronologies are commonly applied to study the dynamics of massive, abrupt climate changes characteristic of the transition between the Last Glacial Maximum and the present interglacial climate. This article reviews developments in exposure dating from the perspective of whether this goal is achievable and concludes that ( a) individual exposure-dated landforms cannot, in general, be associated with millennial-scale climate events at high confidence, but ( b) dating uncertainties appear to be geographically and temporally unbiased, so the data set as a whole can be used to gain valuable insight into regional and global paleoclimate dynamics. Future applications of exposure-age chronologies of glacier change should move away from reliance on individual dated landforms and toward synoptic analysis of the global data set. ▪ Mountain glaciers worldwide leave a geologic record of their past advances and retreats, which reflect past climate changes. ▪ Geochemical dating methods based on cosmic-ray-produced nuclides have been used to date these deposits at thousands of sites worldwide. ▪ This data set is potentially an extensive, accessible, and globally distributed paleoclimate record.
{"title":"Glacier Change and Paleoclimate Applications of Cosmogenic-Nuclide Exposure Dating","authors":"G. Balco","doi":"10.1146/annurev-earth-081619-052609","DOIUrl":"https://doi.org/10.1146/annurev-earth-081619-052609","url":null,"abstract":"Surface exposure dating using cosmic-ray-produced nuclides has been applied to determine the age of thousands of landforms produced by alpine glaciers in mountain areas worldwide. These data are potentially an extensive, easily accessible, and globally distributed paleoclimate record. In particular, exposure-dated glacier chronologies are commonly applied to study the dynamics of massive, abrupt climate changes characteristic of the transition between the Last Glacial Maximum and the present interglacial climate. This article reviews developments in exposure dating from the perspective of whether this goal is achievable and concludes that ( a) individual exposure-dated landforms cannot, in general, be associated with millennial-scale climate events at high confidence, but ( b) dating uncertainties appear to be geographically and temporally unbiased, so the data set as a whole can be used to gain valuable insight into regional and global paleoclimate dynamics. Future applications of exposure-age chronologies of glacier change should move away from reliance on individual dated landforms and toward synoptic analysis of the global data set. ▪ Mountain glaciers worldwide leave a geologic record of their past advances and retreats, which reflect past climate changes. ▪ Geochemical dating methods based on cosmic-ray-produced nuclides have been used to date these deposits at thousands of sites worldwide. ▪ This data set is potentially an extensive, accessible, and globally distributed paleoclimate record.","PeriodicalId":8034,"journal":{"name":"Annual Review of Earth and Planetary Sciences","volume":null,"pages":null},"PeriodicalIF":14.9,"publicationDate":"2020-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86679276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-29DOI: 10.1146/annurev-earth-071719-055104
L. Wallace
Continuously operating global positioning system sites in the North Island of New Zealand have revealed a diverse range of slow motion earthquakes on the Hikurangi subduction zone. These slow slip events (SSEs) exhibit diverse characteristics, from shallow (<15 km), short (<1 month), frequent (every 1–2 years) events in the northern part of the subduction zone to deep (>30 km), long (>1 year), less frequent (approximately every 5 years) SSEs in the southern part of the subduction zone. Hikurangi SSEs show intriguing relationships to interseismic coupling, seismicity, and tectonic tremor, and they exhibit a diversity of interactions with large, regional earthquakes. Due to the marked along-strike variations in Hikurangi SSE characteristics, which coincide with changes in physical characteristics of the subduction margin, the Hikurangi subduction zone presents a globally unique natural laboratory to resolve outstanding questions regarding the origin of episodic, slow fault slip behavior. ▪ New Zealand's Hikurangi subduction zone hosts slow slip events with a diverse range of depth, size, duration, and recurrence characteristics. ▪ Hikurangi slow slip events show intriguing relationships with seismicity ranging from small earthquakes and tremor to larger earthquakes. ▪ Slow slip events play a major role in the accommodation of plate motion at the Hikurangi subduction zone. ▪ Many aspects of the Hikurangi subduction zone make it an ideal natural laboratory to resolve the physical processes controlling slow slip.
{"title":"Slow Slip Events in New Zealand","authors":"L. Wallace","doi":"10.1146/annurev-earth-071719-055104","DOIUrl":"https://doi.org/10.1146/annurev-earth-071719-055104","url":null,"abstract":"Continuously operating global positioning system sites in the North Island of New Zealand have revealed a diverse range of slow motion earthquakes on the Hikurangi subduction zone. These slow slip events (SSEs) exhibit diverse characteristics, from shallow (<15 km), short (<1 month), frequent (every 1–2 years) events in the northern part of the subduction zone to deep (>30 km), long (>1 year), less frequent (approximately every 5 years) SSEs in the southern part of the subduction zone. Hikurangi SSEs show intriguing relationships to interseismic coupling, seismicity, and tectonic tremor, and they exhibit a diversity of interactions with large, regional earthquakes. Due to the marked along-strike variations in Hikurangi SSE characteristics, which coincide with changes in physical characteristics of the subduction margin, the Hikurangi subduction zone presents a globally unique natural laboratory to resolve outstanding questions regarding the origin of episodic, slow fault slip behavior. ▪ New Zealand's Hikurangi subduction zone hosts slow slip events with a diverse range of depth, size, duration, and recurrence characteristics. ▪ Hikurangi slow slip events show intriguing relationships with seismicity ranging from small earthquakes and tremor to larger earthquakes. ▪ Slow slip events play a major role in the accommodation of plate motion at the Hikurangi subduction zone. ▪ Many aspects of the Hikurangi subduction zone make it an ideal natural laboratory to resolve the physical processes controlling slow slip.","PeriodicalId":8034,"journal":{"name":"Annual Review of Earth and Planetary Sciences","volume":null,"pages":null},"PeriodicalIF":14.9,"publicationDate":"2020-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81510836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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