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Over geologic time sea level has fluctuated by more than 300 metres, possibly more than 400 metres. The main reasons for sea level fluctuations in the last 15 million years are the Antarctic ice sheet and Antarctic post-glacial rebound during warm periods. The current sea level is about 130 metres higher than the historical minimum.
Sea surface height change from 1992 to 2019: Blue regions are where sea level has gone down, and orange/red regions are where sea level has risen (the visualization is based on satellite data). [ 2 ] Between 1901 and 2018, the average sea level rose by 15–25 cm (6–10 in), with an increase of 2.3 mm (0.091 in) per year since the 1970s.
The annual cycle of sea level height (or seasonal cycle or annual harmonic) describes the variation of sea level that occurs with a period of one year. Historically, analysis of the annual cycle has been limited by locations with tide gauge records, i.e., coastlines and some islands in the deep ocean, and by sparse records in the Southern Hemisphere.
Tidal range is the difference in height between high tide and low tide. Tides are the rise and fall of sea levels caused by gravitational forces exerted by the Moon and Sun, by Earth's rotation and by centrifugal force caused by Earth's progression around the Earth-Moon barycenter.
The EHSLR spans Meltwater pulses 1B and 1C, between 12,000 and 7,000 years ago: Meltwater pulse 1B between c. 11.4–11.1 ka, a 7.5 m (25 ft) rise over about 160 years centered at 11.1 ka, which includes the end of Younger Dryas interval of reduced sea level rise at about 6.0–9.9 mm (0.2–0.4 in)/yr;
Local mean sea level (LMSL) is defined as the height of the sea with respect to a land benchmark, averaged over a period of time long enough that fluctuations caused by waves and tides are smoothed out, typically a year or more.
Image showing sea level change during the end of the last glacial period. Meltwater pulse 1A is indicated. Meltwater pulse 1A (MWP1a) is the name used by Quaternary geologists, paleoclimatologists, and oceanographers for a period of rapid post-glacial sea level rise, between 13,500 and 14,700 years ago, during which the global sea level rose between 16 meters (52 ft) and 25 meters (82 ft) in ...
This order of sea-level change has yet to be fully explained. It was originally thought that glaciers controlled these sea-level changes. But glaciers form and retreat far too rapidly, only tens of thousands of years instead of over a million years. Instead, short-term changes in earth's surface due to volcanics and tectonic events could change ...