Global Sea Levels
The global sea levels reflect the state of the world's climate. The stability of today's sea level is due to the equal balance of precipitation and evaporation, whilst the actual level is due to amount of frozen water presently locked up in the polar icecaps.

During the many ice ages that have descended upon our planet, the global sea level dropped in response to the ice caps cooling off further and expanding, effectively locking up more and more water which would have formerly been fed back into the ocean.

The potential for the green house effect to heat up global temperatures by trapping more and more solar heat in the atmosphere is now seen as possibly strong enough to affect the world's ocean currents. Global warming could precipitate two separate threats to us.

The first threat would be a global rising of the seas due to more ice cap melting than being laid down. This increases the ratio of the planet's water in liquid form against that stored as solid ice. Whilst a sea level rise of a meter of so would be catastrophic for many of our low lying nations such as the Netherlands and Bangladesh, its immediate threat would be restricted to coastal zones, The second threat could be a change or potential reversal of our main oceanic currents- which affect our weather and our fish stocks. This could affect most of our biosphere. Global crop failure is likely, due to massive temperature fluctuations and increasingly stormy weather, likewise a crash in global fish stocks could also occur.

We are not yet able to predict the impacts which could happen once a stage of major climate change has been started such as a reversal or slowing down of the Gulf Stream.