How much will sea level rise by 2020?

Answer 1

Global sea levels are rising at about 4 mm per year and have been steadily rising for hundreds of years, so we can certainly presume the rise will continue.

A common error in climate debate is to focus on short term data instead of looking at long time trends. All sea level graphs (as well as temperature graphs) zig zag up and down. Some years sea levels go down, and the oceans cool: other years oceans warm and sea levels rise, from cyclic events like La Niña (cooling) and El Niño (warming). Some people try to argue that a downward zag means the sea level rise has stopped, but the long term trend shows that sea levels are rising.

Answer:

Since late 2009 there has been no increase in sea level rise. In fact 2010 saw a decrease in height by 6 mm. 2011 saw a decrease of 5 mm. No one actually knows what the future will hold in terms of sea level rise. The trend though for thousands if years has been about 2 mm a year increase.

Answer 2

Sea level is currently about 210 mm above the 1880 average. At 3 mm per year it should only rise another 20 mm by 2020, though accelerating polar ice loss may push this to 250 mm above the 1880 average.

Answer 3

Sea levels rose 20 centimetres over the course of the twentieth century, an average of only 2 millimetres per year. During the last decade, however, mean global sea levels have been rising at approximately 2.9 to 3.4 millimetres per year. The two years, 2010-2011, have shown no increase and even a significant decrease, which is attributed to the El Nino/La Nina cycle.

Answer 4

Yes. Rising sea levels are a global effect. Sea levels rose by only 20 centimetres in the twentieth century, but are now expected to rise by 90 to 150 centremetres during the present century.