The mean sea level, commonly known as the “sea level” is the mean level of the ocean’s surface from which an altitude can be measured. Sea levels are affected by several factors and vary widely across the geological time scale. The measurement of the mean sea level can give insight into the effects of climate change. The rise of the sea level has been an indication of the progress of global warming. The term “above sea level” is a common phrase used when measuring the altitude of an area. It refers to the above mean sea level.
How Is Sea Level Measured?
The determination of the mean sea level is a challenging task considering the several factors which affect sea level. The sea is always in constant movement, influenced by several factors including tides, temperatures, storm surges and wind. Before the invention of the satellite systems, mean sea levels were measured using the tide gauge device that measured the height of water about a fixed point on land. A change in the mean sea level can be influenced by real changes in the sea level or changes in the land on which the tide gauge is used. Tide gauge reflects a short-term influence of the factors affecting the sea level introducing a larger margin of error. Satellite has been giving exact measurements of the sea levels since the launch in 1992. The assessments of the sea level indicate that the levels have risen between 0.5 mm and 0.3mm a year since the 20th century.
The Alarming Rise In Global Sea Levels
The sea level rise is the increase in the quantity of water in the oceans around the world leading to an increase in the mean sea level. The sea levels accelerated in the 20th century faster than in previous centuries. The mean sea levels can be seen rising when the satellite and the tide gauge are used. The mean air temperature is rising in relation to global warming which is reducing the ice volume on the earth. The sea level rise is posing a challenge to coastal communities and the surrounding ecosystems. The sea levels increased by 60.8 mm between 1998 and 2015 relative to 1997 levels. The levels increased by only 5.2 mm between 1997 and 1998 and 6.8 mm between 2000 and 2002. The highest sea level rise during the period occurred between 2008 and 2010 when the levels increased by 9.8 mm. The increase in the sea level is attributed to the meltwater events.
A Catastrophe Waiting To Happen?
The rising sea level is one of the greatest threats posed by climate change. The low-lying countries are at risk of inundation, forcing the majority to migrate. The coastal cities and ports are in danger of flooding. The potential for further sea rise is enormous considering that the ice cap contains a vast amount of freshwater. If the Greenland ice sheet was to melt away then the sea levels would increase by about six meters, which is a very significant amount. The future sea level rise depends on several factors including the amount of greenhouse gasses emitted which will determine the rate of global warming and the amount of ice that melts which also depends on the amount of global warming.
How Much Has The Sea Level Risen Since 1997?
|Cumulative Sea Level Rise Since 1997 (in mm)