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Sea Level Change, Variability and Forecasting

Sea level and its change has been measured for more than a century. Especially, for nations with long coastlines and important coastal industry observations of tides, extremes, and long-term changes have strong economic impacts.

Today, the observed sea level rise (SLR) is largely associated with climate related changes. To find the patterns and fingerprints of those changes, different monitoring techniques have been developed. Some of them are local, e.g. tide gauges, others are global, e.g., radar altimetry. In many areas, the slow long-term rise in sea level is superimposed by artificial and sometimes natural changes, which might have much higher rates in relative sea level rise. Reasons for that are e.g., groundwater, gas or oil extraction in near-shore areas or changes in the coastal habitat.

GGOS and it’s services contribute in many ways to the monitoring of the sea level. This ranges from tide gauge observations, estimation of gravity changes, GNSS control of tide gauges or the maintenance of the International Reference Frame.

Theme 3 of GGOS establishes a platform and will be a forum to researchers and authorities for estimating and predicting global and local sea level changes in a 10- to 30-year time horizon.

Sea level rise and its impact on human habitats and
economic well being is one of the key issues in the climate
change discussion. In recent years this topic has received
considerable and growing attention by the general public,
engineers, researchers, and policy makers and calls for
multi-disciplinary research. In 2010 GGOS has identified
sea level change as one of the cross-cutting themes for
geodesy and established this topic as one of its Focus
Areas. The primary task of Focus Area 3 is to demonstrate
the value of different geodetic techniques available under
the umbrella of GGOS to the mitigation of sea level rise
including studies of the impacts of its change over the
world’s coastal regions and islands, and to support
practical applications such as sustainability.
Focus Area 3 interacts with the other two Focus Areas
as well as with the related Committees and Working
Groups of the GGOS Bureaus. Close cooperation is
established and will be intensified with groups and
organizations working in related fields. One major topic is
the identification of gaps and their closure in geodetic
observing techniques and networks and to advocate
additions in the GGOS monitoring network and Services
where necessary.
Activities
Through the projects accepted ongoing Call for Participation
Focus Area 3 will progress with the following tasks:
-> Identification or (re)-definition of the requirements for a
roper understanding of global and regional/local sea
level rise and its variability especially in so far as they
elate to geodetic monitoring provided by the GGOS
Infrastructure, and their current links to external
organizations (e.g., GEO, CEOS, and other observing
systems).
-> Identification of gaps in geodetic observing techniques
contributing to sea level research and advocate
improvements and additions in the GGOS monitoring
network and Services where necessary
-> Establishing Focus Area 3 as the interface and point-ofcontact
between GGOS and organizations concerned
with sea level research aspects
-> In the long-term, the aim is to support forecasting of
global and regional sea level for the 21st century.
Special emphasis will be given to local and regional
projects which re relevant to coastal communities, and
which depend on the global perspective of GGOS.

Global Mean Sea Level (middle, vertical scale exaggerated) and some supporting methodsGlobal Mean Sea Level (middle, vertical scale exaggerated) and some supporting methods

Bureau of Networks and Observations

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Bureau of Products and Standards

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Focus Area

Unified Height System

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Geohazards Monitoring

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Focus Area

Sea Level Change, Variability, and Forecasting

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Focus Area

Geodetic Space Weather Research

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GGOS Core Sites