Three historic tide gauge records from the Arctic archipelago of Svalbard have been converted from tabulations more than one century old into computer files. The records are found to be good quality and capable of being used in modern tidal analysis. The analyses confirm the findings on tidal constants by previous researchers and demonstrate how little non-tidal variability in sea level there was at these times. One of the tide gauges used was a crude contraption of a design not used before or since. Nevertheless, it appears to have worked well and so deserves to be better known.

Abstract Coastal water level measurements represent one of the earliest geophysical measurements and allow an assessment of historical sea level rise and trends in tides, river flow and storm surge. However, recovery and digitization of archival tidal records have been much less widespread and systematic than, for example meteorological records. In this contribution, we discuss data rescue efforts and lessons learned in France, the United States and the United Kingdom, countries with early and extensive tide gauge networks by the mid‐19th century. We highlight the importance of (a) cataloguing the historical gauge records, as a first step towards locating them; (b) locating data in archives, and then recovering and saving data by any means necessary, including photographs and scanning; (c) obtaining metadata, including both quantitative survey records, gauge checks and clock data, but also qualitative records such as gauge notes, letters and reports; and (d) quantitative statistical analysis of data and datum quality, using both standard data‐entry checks but also tools that leverage the unique predictability of tide measurements. Methods for digitizing original analogue records are also discussed, including semi‐automatic, computer‐based methods of digitizing tidal charts (marigrams). Although the current best practice is described, future improvements are desirable and needed to make the more than estimated 10,000 station years of unused, undigitized records available to the scientific community.

Our civilization needs a clean, resilient, productive, safe, well-observed, documented and predicted ocean. "The ocean we need for the future we want" was the motto of the Intergovernmental Oceanographic Commission proposal to the United Nations to consider the merit of an Ocean Science Decade. By proclaiming the Decade, the UN General Assembly offered the oceanographic community a unique, once in a life-time, opportunity to change the way we do things, make oceanography fit for purpose of effectively supporting sustainable development, and energize the ocean sciences for future generations. The Decade is the chance to put in place a more complete and sustainable observing system and feed the resulting data into a science-based informed decision-making system allowing increased reliance of our civilization on the ocean, its ecosystem services and, at the same time, preserving ocean health. Strong and proactive engagement of the oceanographic community in the design of the Decade and its observing component and subsequent energetic implementation of the ideas are sought. Participants in OceanObs'19 are invited to consider the additional possibilities and requirements associated with the Decade in their contributions to and brainstorming at the Conference. It is essential to use collective wisdom of OceanObs'19 to help developing an ambitious and also realistic implementation plan for the Decade, with a strong observational component.

The Global Sea Level Observing System (GLOSS) Group of Experts (GE) data archaeology group is collating tools and producing guidelines for historic sea level data. They aim to aid the discovery, scanning, digitising and quality control of analogue tide gauge charts and sea level ledgers. Their goal is to improve the quality, quantity and availability of long-term sea level data series. This paper examines different tools for the automatic digitisation of tide gauge charts, the methods available for transcribing handwritten tide gauge ledgers and possible future developments that might speed up and partially automate these processes.

The main component of the Global Sea Level Observing System (GLOSS) is the GLOSS Core Network (GCN) of 290 sea level stations. The present definition of the GCN (the definition is modified every few years) is called GLOSS10. In 2012 a new GLOSS implementation plan was developed to update technical standards for GLOSS tide gauge stations, as well as describing the basic terms and obligations for Member States participating in GLOSS. The British Oceanographic Data Centre (BODC) and the Permanent Service for Mean Sea Level (PSMSL) run the GLOSS Delayed Mode Data Centre jointly. It is responsible for assembling, quality controlling and distributing the "final" version of GLOSS sea level data sets and their supporting metadata, as well as carrying out data archaeology on historical analogue sea level records, preserving them in digital form. It also maintains the GLOSS Station Handbook and GLOSS website.

Chapter 13 Sea-Level Rise and Variability: Synthesis and Outlook for the Future John A. Church, John A. Church oceanographer [email protected] Centre for Australian Weather and Climate Research, AustraliaSearch for more papers by this authorThorkild Aarup PhD, Thorkild Aarup PhD Senior Program Specialist technical secretary [email protected] Intergovernmental Oceanographic Commission, Unesco, Paris, FranceSearch for more papers by this authorPhilip L. Woodworth, Philip L. Woodworth former Director Chairman [email protected] Proudman Oceanographic Laboratory, Liverpool, UKSearch for more papers by this authorW. Stanley Wilson, W. Stanley Wilson Senior Scientist [email protected] NOAA Satellite & Information Service, Silver Spring, Maryland, USASearch for more papers by this authorRobert J. Nicholls, Robert J. Nicholls [email protected] School of Civil Engineering and the Environment, and the Tyndall Centre for Climate Change Research, University of Southampton, Southampton, UKSearch for more papers by this authorRalph Rayner, Ralph Rayner [email protected] Institute of Marine Engineering, Science and Technology, London, UKSearch for more papers by this authorKurt Lambeck, Kurt Lambeck [email protected] Research School of Earth Sciences, Australian National University, Canberra, Australia Antarctic Climate and Ecosystems Cooperative Research Centre, AustraliaSearch for more papers by this authorGary T. Mitchum, Gary T. Mitchum [email protected] College of Marine Sciences, University of South Florida, St. Petersburg, FL, USASearch for more papers by this authorKonrad Steffen, Konrad Steffen [email protected] CIRES (Cooperative Institute for Research in Environmental Sciences), University of Colorado, Boulder, CO, USASearch for more papers by this authorAnny Cazenave, Anny Cazenave [email protected] Laboratoire d'Etudes en Géophysique et Océanographie, Toulouse, FranceSearch for more papers by this authorGeoff Blewitt, Geoff Blewitt [email protected] Nevada Bureau of Mines and Geology, University of Nevada, Reno, NV, USASearch for more papers by this authorJerry X. Mitrovica, Jerry X. Mitrovica [email protected] Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USASearch for more papers by this authorJason A. Lowe, Jason A. Lowe [email protected] The Hadley Centre, Met Office, UKSearch for more papers by this author John A. Church, John A. Church oceanographer [email protected] Centre for Australian Weather and Climate Research, AustraliaSearch for more papers by this authorThorkild Aarup PhD, Thorkild Aarup PhD Senior Program Specialist technical secretary [email protected] Intergovernmental Oceanographic Commission, Unesco, Paris, FranceSearch for more papers by this authorPhilip L. Woodworth, Philip L. Woodworth former Director Chairman [email protected] Proudman Oceanographic Laboratory, Liverpool, UKSearch for more papers by this authorW. Stanley Wilson, W. Stanley Wilson Senior Scientist [email protected] NOAA Satellite & Information Service, Silver Spring, Maryland, USASearch for more papers by this authorRobert J. Nicholls, Robert J. Nicholls [email protected] School of Civil Engineering and the Environment, and the Tyndall Centre for Climate Change Research, University of Southampton, Southampton, UKSearch for more papers by this authorRalph Rayner, Ralph Rayner [email protected] Institute of Marine Engineering, Science and Technology, London, UKSearch for more papers by this authorKurt Lambeck, Kurt Lambeck [email protected] Research School of Earth Sciences, Australian National University, Canberra, Australia Antarctic Climate and Ecosystems Cooperative Research Centre, AustraliaSearch for more papers by this authorGary T. Mitchum, Gary T. Mitchum [email protected] College of Marine Sciences, University of South Florida, St. Petersburg, FL, USASearch for more papers by this authorKonrad Steffen, Konrad Steffen [email protected] CIRES (Cooperative Institute for Research in Environmental Sciences), University of Colorado, Boulder, CO, USASearch for more papers by this authorAnny Cazenave, Anny Cazenave [email protected] Laboratoire d'Etudes en Géophysique et Océanographie, Toulouse, FranceSearch for more papers by this authorGeoff Blewitt, Geoff Blewitt [email protected] Nevada Bureau of Mines and Geology, University of Nevada, Reno, NV, USASearch for more papers by this authorJerry X. Mitrovica, Jerry X. Mitrovica [email protected] Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USASearch for more papers by this authorJason A. Lowe, Jason A. Lowe [email protected] The Hadley Centre, Met Office, UKSearch for more papers by this author Book Editor(s):John A. Church, John A. Church oceanographer Centre for Australian Weather and Climate Research, AustraliaSearch for more papers by this authorPhilip L. Woodworth, Philip L. Woodworth former Director Chairman Proudman Oceanographic Laboratory, Liverpool, UKSearch for more papers by this authorThorkild Aarup PhD, Thorkild Aarup PhD Senior Program Specialist technical secretary Intergovernmental Oceanographic Commission, Unesco, Paris, FranceSearch for more papers by this authorW. Stanley Wilson, W. Stanley Wilson Senior Scientist NOAA Satellite & Information Service, Silver Spring, Maryland, USASearch for more papers by this author First published: 05 July 2010 https://doi.org/10.1002/9781444323276.ch13Citations: 25 AboutPDFPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShareShare a linkShare onEmailFacebookTwitterLinkedInRedditWechat Summary This chapter contains sections titled: Historical Sea-Level Change Why is Sea Level Rising? 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Three sea level stations with extensive historical information have recently been equipped with new technology tide gauges, following large gaps in recording at the stations. The new and historical data in combination provide information on the rates of sea level rise along parts of the global coastline not well- represented in scientific studies to date. In these cases, the rates were found to be similar to those observed at many other locations around the world. However, it is suggested that other stations, where historical data exist and where gaps in recording have occurred, could be similarly equipped with new gauges, thereby expanding the spatial coverage of our knowledge of sea level rise.

The coastal zone has changed profoundly during the 20th century and, as a result, society is becoming increasingly vulnerable to the impact of sea-level rise and variability. This demands improved understanding to facilitate appropriate planning to minimise potential losses. With this in mind, the World Climate Research Programme organised a workshop (held in June 2006) to document current understanding and to identify research and observations required to reduce current uncertainties associated with sea-level rise and variability. While sea levels have varied by over 120 m during glacial/interglacial cycles, there has been little net rise over the past several millennia until the 19th century and early 20th century, when geological and tide-gauge data indicate an increase in the rate of sea-level rise. Recent satellite-altimeter data and tide-gauge data have indicated that sea levels are now rising at over 3 mm year −1 . The major contributions to 20th and 21st century sea-level rise are thought to be a result of ocean thermal expansion and the melting of glaciers and ice caps. Ice sheets are thought to have been a minor contributor to 20th century sea-level rise, but are potentially the largest contributor in the longer term. Sea levels are currently rising at the upper limit of the projections of the Third Assessment Report of the Intergovernmental Panel on Climate Change (TAR IPCC), and there is increasing concern of potentially large ice-sheet contributions during the 21st century and beyond, particularly if greenhouse gas emissions continue unabated. A suite of ongoing satellite and in situ observational activities need to be sustained and new activities supported. To the extent that we are able to sustain these observations, research programmes utilising the resulting data should be able to significantly improve our understanding and narrow projections of future sea-level rise and variability.

The coastal zone changed considerably during the twentieth century due to growing populations and increasing urbanization. A recent study indicated that in 1990, 23% of the world's population (1.2 billion people) were living within both a 100‐kilometer distance and a 100‐meter elevation of the coast at densities 3 times higher than the global average. Society is becoming increasingly vulnerable to sea level extremes, as Hurricane Katrina demonstrated. Rising levels will result in more flooding, even if storm intensities do not increase. Improved understanding of the reasons for sea level rise and variability is required to reduce the uncertainties in sea level rise projections, and this improved understanding could contribute to more effective coastal planning and management.

This short note reviews our thinking on how IGGOS can best achieve a high status within the set of global monitoring programmes. If such a high status can be obtained, then the importance of geodetic networks and services will be recognized more widely, and their activities will consequently be better resourced in the long term. One particular aspect concerns how IGGOS can complement the roles of the various IGOS partners within global monitoring. The different ways in which IGGOS can contribute to IGOS are outlined.

Sea level is such a fundamental parameter in the sciences of oceanography geophysics, and climate change, that in the mid‐1980s, the Intergovernmental Oceanographic Commission (IOC) established the Global Sea Level Observing System (GLOSS). GLOSS was to improve the quantity and quality of data provided to the Permanent Service for Mean Sea Level (PSMSL), and thereby, data for input to studies of long‐term sea level change by the Intergovernmental Panel on Climate Change (IPCC). It would also provide the key data needed for international programs, such as the World Ocean Circulation Experiment (WOCE) and later, the Climate Variability and Predictability Programme (CLIVAR).GLOSS is now one of the main observation components of the Joint Technical Commission for Oceanography and Marine Meteorology (JCOMM) of IOC and the World Meteorological Organization (WMO). Progress and deficiencies in GLOSS were presented in July to the 22nd IOC Assembly at UNESCO in Paris and are contained in the GLOSS Assessment Report (GAR) [IOC, 2003a].

This paper presents the results of a Secchi depth data mining study for the North Sea – Baltic Sea region. 40,829 measurements of Secchi depth were compiled from the area as a result of this study. 4.3% of the observations were found in the international data centers [ICES Oceanographic Data Center in Denmark and the World Ocean Data Center A (WDC–A) in the USA], while 95.7% of the data was provided by individuals and ocean research institutions from the surrounding North Sea and Baltic Sea countries. Inquiries made at the World Ocean Data Center B (WDC–B) in Russia suggested that there could be significant additional holdings in that archive but, unfortunately, no data could be made available. The earliest Secchi depth measurement retrieved in this study dates back to 1902 for the Baltic Sea, while the bulk of the measurements were gathered after 1970. The spatial distribution of Secchi depth measurements in the North Sea is very uneven with surprisingly large sampling gaps in the Western North Sea. Quarterly and annual Secchi depth maps with a 0.5 ◦ ×0.5 ◦ spatial resolution are provided for the transition area between the North Sea and the Baltic Sea (4 ◦ E–16 ◦ E, 53 ◦ N–60 ◦ N).