Science News Archive

Gravity may make sea level rise worse

If the world is going to warm up then this is going to cause the sea level to rise. As water warms up it expands so it takes up more space and as ice on the continents melts it dumps more water into the oceans. Many models predict the melting of the west antarctic ice sheet which is predicted to produce a 5m rise in sea level, but researchers from the university of Toronto have noticed that these models haven't taken something important into account.

And that's gravity. Everything with mass attracts everything else with mass gravitationally. So the 22 million billion tonnes of ice in the ice sheet are attracting the sea water around them. This lifts the local sea level creating a bulge around the ice sheet. So when the ice sheet melts you not only get a redistribution of the water in the sheetbut around it too. Also moving around thousands of cubic kilometers of water could cause the earth's axis to move by as much as five hundred metres which will move where the centrifugal bulge of the earth is acting changing the shape of the earth and the oceans above it.

The overall effect of all this is that the sea level aroung north america and the southern indian ocean could rise an extra 1.5m on top of the 5m already predicted and the sea around west antarctica could only rise 4m instead of 5.

8th Feb 2009