sea level changes

Antarctica as a whole has caused a total of 7.6 ± 3.9 mm (0.30 ± 0.15 in) of sea level rise. In the recent geological past, changes in land ice and thermal expansion from increased temperatures are the dominant reasons of sea level rise. This has consequences for Europe and the Current and future sea level rise is set to have a number of impacts, particularly on Globally tens of millions of people will be displaced in the latter decades of the century if greenhouse gases are not reduced drastically. By the year 2050, 150 million will be under the water line during high tide and 300 million will live in zones with floodings every year. Some of the recorded regional differences are due to differences in the actual sea level, while other are due to vertical land movements. Tide gauges measure relative sea level change at points along the coast, while satellite instruments measure absolute sea level change over nearly the entire ocean surface. In high emission scenario, it will be 34 cm by 2050 and 111 cm by 2100. Join NASA Earth scientists for a 360-degree view of our planet as they head into the field to study Greenland ice and Hawaiian coral reefs.

Sea level, position of the air-sea interface, to which all terrestrial elevations and submarine depths are referred. Since then, the rate of rise has increased substantially; from 1900 to 2012, sea level rose by a global average of about 19 centimetres. Find out more about how NASA satellite observations help our understanding of this complex topic. NASA, University of Nebraska release new global groundwater maps and U.S. drought forecasts This follows several thousand years when there was a slow fall of Australian sea levels relative to the land at rates of a few centimetres per century. The first graph tracks the change in sea level since 1993 as observed by satellites. Relative sea level data are available from the National Oceanic and Atmospheric Administration, which publishes an interactive online map (

For the east and west coasts of Australia, this happened three times more often in the second half compared to the first half of the 20th century. Furthermore, two thirds of the world's cities with over five million people are located in these low-lying coastal areas.Rising seas has also been tied to an increased risk from Food production in coastal areas is affected by rising sea levels as well. The two major causes of global sea level rise are thermal expansion caused by warming of the ocean (since water expands as it warms) and increased melting of land-based ice, such as glaciers and ice sheets. This effect will continue with more than a ten-fold increase in the frequency of extreme sea levels by 2100 at many locations and a much increased risk of coastal flooding and erosion, even for a low emissions pathway.By 2300, it is projected that high greenhouse gas emissions could lead to a global sea-level rise of 1 metre to 3 metres or more. The term "steric" refers to global changes in sea level due to thermal expansion and salinityvariations. Average sea levels have swelled over 8 inches (about 23 cm) since 1880, with about three of those inches gained in the last 25 years… In high emission scenario, the numbers arrive to 540 million and 640 million respectively. A similarly high rate was experienced in the 1920 to 1950 period (Figure 6.1).The two largest contributions to sea-level rise since 1900 were the expansion of ocean water as it warmed, and the addition of water to the ocean from loss of ice from glaciers. This indicator presents trends in sea level based on measurements from tide gauges and from satellites that orbit the Earth. When the term "relative" is used, it means change relative to a fixed point in the sediment pile.

Observations indicate that an increased discharge from Antarctica is occurring, particularly from sectors of the Antarctic ice sheet resting on land below sea level. In the past 20 years, both satellite and coastal sea-level data indicate that the rate of rise has increased to about 3 centimetres per decade.

For Australia, 21st century sea-level rise is likely to be close to the global average rise.In addition to climate-driven sea-level change, local factors can also be important and may dominate at some locations. Satellite data are based solely on measured sea level, while the long-term tide gauge data include a small correction factor because the size and shape of the oceans are changing slowly over time. Although this is a slow and continuous process, but its long-term cumulative effect on the world, especially in the coastal areas caused serious danger. This area can be significant as rights extend to a radius of 224 nautical miles (415 km; 258 mi) around the entire island state. According to a Climate Central report this week, “Sea level rise is one of the best known of climate change’s many dangers. This would occur above a warming threshold estimated to be between about 1°C and 4°C of global average warming relative to pre-industrial temperatures. In Europe for instance, considerable variation is found because some land areas are rising while others are sinking. Since 1990, there have been further contributions from surface melting of the Greenland ice sheet, and the increased discharge of ice into the ocean from both the Greenland and Antarctic ice sheets.