'Many hurricanes' in modern times

Richard Black in the BBC: Hurricanes in the Atlantic are more frequent than at any time in the last 1,000 years, according to research just published in the journal Nature. Scientists examined sediments left by hurricanes that crossed the coast in North America and the Caribbean.

The record suggests modern hurricane activity is unusual - though it might have been even higher 1,000 years ago. The possible influence of climate change on hurricanes has been a controversial topic for several years.

Study leader Michael Mann from Penn State University believes that while not providing a definitive answer, this work does add a useful piece to the puzzle. "It's been hotly debated, and various teams using different computer models have come up with different answers," he told BBC News. "I would argue that this study presents some useful palaeoclimatic data points."

Hurricanes strike land with winds blowing at up to 300km per hour - strong enough to pick up sand and earth from the shore and carry it inland. In places where there is a lagoon behind the shoreline, this leads to "overwash" - material from the shore being deposited in the lagoon, where it forms a layer in the sediment.

Researchers have studied eight such lagoons on shores where Atlantic hurricanes regularly make landfall - seven around the US mainland and one in Puerto Rico. Over time, Dr Mann's team believes, the number of hurricanes making landfall on these sites will be approximately proportional to the total number of hurricanes formed - so these zones provide a long-term record of how hurricane frequency has changed over the centuries.

2005's Hurricane Wilma crossing Cozumel, NASA