There is much concern over rising sea levels and disappearing coastline. Yet how are such changes really measured?
Satellites can measure tiny changes in sea levels referenced to a known baseline, but those measurements have only been available since 1993. Two other methods used for changes occurring over more than 100 years are tide gauges and efforts by the United Nations‘ Intergovernmental Panel on Climate Change (IPCC) in computer modeling.
A tide gauge monitors water level changes in relation to a local reference height. They are simple devices, not too different from a pingpong ball floating in a tube. Tide gauge data are available for more than 1,750 stations around the world and are the longest time series available.… Seguir leyendo »