Suchergebnisse

"This book will cover all aspects of modern sea-level studies, with a focus on the most robust scientific approaches and techniques"--

Building robust age-depth models to understand climatic and geologic histories from coastal sedimentary archives often requires composite chronologies consisting of multi-proxy age markers. Pollen chronohorizons derived from a known change in vegetation are important for age-depth models, especially those with other sparse or imprecise age markers. However, the accuracy of pollen chronohorizons compared to other age markers and the impact of pollen chronohorizons on the precision of age-depth models, particularly in salt marsh environments, is poorly understood. Here, we combine new and published pollen data from eight coastal wetlands (salt marshes and mangroves) along the Atlantic Coast of the United States (U.S.) from Florida to Connecticut to define the age and uncertainty of 17 pollen chronohorizons. We found that 13 out of 17 pollen chronohorizons were consistent when compared to other age markers (radiocarbon, radionuclide 137Cs and pollution markers). Inconsistencies were likely related to the hyperlocality of pollen chronohorizons, mixing of salt marsh sediment, reworking of pollen from nearby tidal flats, misidentification of pollen signals, and inaccuracies in or misinterpretation of other age markers. Additionally, in a total of 24 models, including one or more pollen chronohorizons, increased precision (up to 41 years) or no change was found in 18 models. ; Ministry of Education (MOE) ; National Research Foundation (NRF) ; Published version ; MC was funded by the National Science Foundation EAR 1624551. NSK, TS, and BPH were funded by the Ministry of Education Academic Research Fund MOE2018-T2-1-030 and MOE2019-T3-1-004, the National Research Foundation Singapore, and the Singapore Ministry of Education, under the Research Centres of Excellence initiative. This article is a contribution to International Geoscience Program (IGCP) Project 639, "Sea Level Change from Minutes to Millennia". This work is Earth Observatory of Singapore contribution 349. AP wishes to acknowledge the funding Science Foundation Ireland Career Development Award (17/CDA/4695); an investigator award (16/IA/4520); a Marine Research Programme funded by the Irish Government, co-financed by the European Regional Development Fund (Grant-Aid Agreement No. PBA/CC/18/01); European Union's Horizon 2020 research and innovation programme under grant agreement No 818144; and SFI Research Centre awards 16/RC/3872 and 12/RC/2289_P2.

The tsunami associated with the giant 9.5 M-w 1960 Chile earthquake deposited an extensive sand layer above organic-rich soils near Queule (39.3 degrees S, 73.2 degrees W), south-central Chile. Using the 1960 tsunami deposits, together with eye-witness observations and numerical simulations of tsunami inundation, we tested the tsunami inundation sensitivity of the site to different earthquake slip distributions. Stratigraphically below the 1960 deposit are two additional widespread sand layers interpreted as tsunami deposits with maximum ages of 4960-4520 and 5930-5740 cal BP. This >4500-year gap of tsunami deposits preserved in the stratigraphic record is inconsistent with written and geological records of large tsunamis in south-central Chile in 1575, 1837, and possibly 1737. We explain this discrepancy by: (1) poor preservation of tsunami deposits due to reduced accommodation space from relative sea-level fall during the late Holocene; (2) recently evolved coastal geomorphology that increased sediment availability for tsunami deposit formation in 1960; and/or (3) the possibility that the 1960 tsunami was significantly larger at this particular location than other tsunamis in the past >4500 years. Our research illustrates the complexities of reconstructing a complete stratigraphic record of past tsunamis from a single site for tsunami hazard assessment. ; Puget Sound Energy Graduate Fellowship at Central Washington University; Earthquake Hazards Program of the U.S. Geological Survey; Chilean National Fund for Development of Science and Technology (FONDECYT)Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT)CONICYT FONDECYT [1190258, 1181479]; Millennium Scientific Initiative (ICM) of the Chilean government [NC160025]; National Science Foundation (NSF)National Science Foundation (NSF)National Research Foundation of Korea [EAR-1624533, EAR-1624542]; ANID PIA Anillo [ACT192169] ; Published version ; Puget Sound Energy Graduate Fellowship at Central Washington University; Earthquake Hazards Program of the U.S. Geological Survey; Chilean National Fund for Development of Science and Technology (FONDECYT), Grant/Award Numbers: 1190258, 1181479; Millennium Scientific Initiative (ICM) of the Chilean government, Grant/Award Number: NC160025; National Science Foundation (NSF), Grant/Award Numbers: EAR-1624533, EAR-1624542; ANID PIA Anillo, Grant/Award Number: ACT192169 ; Public domain authored by a U.S. government employee

With its 3,100 miles of tidal shoreline and low-lying rural and urban lands, "The Free State" is one of the most vulnerable to sea-level rise. Historically, Marylanders have long had to contend with rising water levels along its Chesapeake Bay and Atlantic Ocean and coastal bay shores. Shorelines eroded and low-relief lands and islands, some previously inhabited, were inundated. Prior to the 20th century, this was largely due to the slow sinking of the land since Earth's crust is still adjusting to the melting of large masses of ice following the last glacial period. Over the 20th century, however, the rate of rise of the average level of tidal waters with respect to land, or relative sea-level rise, has increased, at least partially as a result of global warming. Moreover, the scientific evidence is compelling that Earth's climate will continue to warm and its oceans will rise even more rapidly. Recognizing the scientific consensus around global climate change, the contribution of human activities to it, and the vulnerability of Maryland's people, property, public investments, and natural resources, Governor Martin O'Malley established the Maryland Commission on Climate Change on April 20, 2007. The Commission produced a Plan of Action1 that included a comprehensive climate change impact assessment, a greenhouse gas reduction strategy, and strategies for reducing Maryland's vulnerability to climate change. The Plan has led to landmark legislation to reduce the state's greenhouse gas emissions and a variety of state policies designed to reduce energy consumption and promote adaptation to climate change.