In 2007 the Intergovernmental Panel on Climate Change estimated that the oceans would rise by between 18 and 59 centimeters by the end of this century. Recently Svetlana Jevrejeva of the Proudman Oceanographic Laboratory has come up with much higher projections. She thinks that the sea level rise will be between 60 and 160 centimetres.
The difference is the way in which the Proudman Laboratory has done its calculations. Traditionally the IPCC calculated two separate things based on their estimates of global warming – the amount of ice that is melting into the sea and the natural increase in the volume of the sea by thermal expansion – expansion as the water gets warmer.
Proudman have taken into account, not just thermal expansion and estimates of global warming, but also natural events which cause the sea to expand or contract.
If, for example, levels of solar radiation reached the lowest levels for 10,000 years, the sea level rise would be in the range of 10 to 20 centimetres. High volcanic activity will also apparently reduce sea level rises.
One thing emerges; the IPCC model for suggesting sea level changes is too simplistic and need revision.