As the world's oceans get warmer, the strongest tropical storms get stronger, climate scientists reported as the remnants of Hurricane Gustav spun out.

"If the seas continue to warm, we can expect to see stronger storms in the future," said James Elsner of Florida State University.

"As far as this year goes, as a season, we did see the oceans warm and I think there's some reason to believe that that's the reason we're seeing the amount of activity we are."

The National Oceanic and Atmospheric Administration predicts 12 to 16 tropical storms between June 1 and November 30 this year, with six to nine hurricanes and two to five major hurricanes.

Many climate scientists have linked stronger storms to rising sea surface temperatures in the North Atlantic and elsewhere, under the so-called heat engine theory: Because warm tropical cyclones feed on warm water, the warmer the water, the more intense the storm.

US researchers looked at 26 years of satellite data, from 1981 to 2006, and determined that the strongest storms got stronger as a result of increasing ocean warmth.

"It's almost like a survival-of-the-fittest argument," said Dr Elsner, whose study is published in the journal Nature. Overall, tropical waters that breed cyclones have warmed by about 0.33°C since 1981.

The heat engine theory suggests all storms should strengthen as the ocean's surface gets hotter, but in reality, few tropical cyclones achieve their full maximum potential intensity.

A cyclone's intensity can be cut by other factors, such as where they form, how close they are to land, El Niño patterns and solar activity, said the researchers.