As temperatures rise, the sea will absorb heat from the atmosphere, causing it to expand and therefore creating sea level rises.

Although ice-sheets in Greenland and Antarctica could be affected by warming temperatures, it isn't thought that they will melt significantly enough to contribute to sea level rises. If they melt over the coming one thousand years, though, due to increased temperatures, oceans could increase in depth by a number of metres. Land glaciers will continue to melt over the coming century which will increase the level of the seas.

In the UK, the effect of sea level rises goes hand in hand with the land movements being experienced across the country. Therefore sea level rises could be different around the coast. Much of southern Britain is sinking and in northern areas the opposite is happening. This, along with the sea level rises, increases the risk of flooding and coastal erosion, particularly in the south and east of England.

This graph shows the sea level as recorded at Sheerness on the Isle of Sheppey.   

This map from the Environment Agency shows a part of Medway that would be regularly flooded if flood defences weren't in place.  As sea levels rise, flood defences will need to be strengthened.