CHANGING storm patterns caused by global warming could dramatically increase the effects of coastal erosion.

Most models of the effects of global warming on coastlines usually assume that rising sea-levels will affect shorelines uniformly along their length. However, this fails to take account of the extra coastal erosion caused by strong waves from higher numbers of tropical storms, says Jordan Slott at Duke University in Durham, North Carolina.

To investigate, Slott and his colleagues modelled how increasingly powerful waves striking the Carolina Capes over the next 200 years would change the shape of the coastline. They assumed that a 2 �C rise in sea surface temperatures would raise wind speeds by 10 per cent.

Rather than eroding the shore uniformly, the team found that the waves removed sand from the beaches in some regions and re-deposited it elsewhere. Significantly, the sea encroached some areas 10 times further than would be expected from rising water levels alone (Geophysical Research Letters, vol 33, p L18404).

Slott points out that some of the fastest-growing communities in North Carolina are building near the coast. "We want those involved in managing coastlines - and the people living there - to realise that the story is more complicated than they might think," says Slott.

From issue 2571 of New Scientist magazine, 30 September 2006, page 20