Countdown to Katrina

So is our weather getting worse? For decades, scientists like Simon Boxall at the Southampton's Oceanographic Institute have understood that hurricanes come in cycles. "These natural cycles are typically ten or fifteen years long. And we've seen periods where we've had low hurricane activity, and we now seem to going to be in an area where we have high hurricane activity, particularly in parts of the North Atlantic'.

But he also feels that change may be happening. The hurricanes we see now seem to be shifting up a gear. Over the last 30 years the number of powerful category 4 and 5 storms has almost doubled. And worse still, sea surface temperatures are rising globally and uniformly. Over the last 30 years, they have risen over half a degree Centigrade.

The reason for the heating of the oceans remains controversial. Some researchers blame manmade global warming, while others finger natural temperature cycles. Simon Boxall is convinced that hurricanes are set to get worse. "One hurricane is the same as one hundred thousand atomic bombs. That's incredible power in just one area, such as the Gulf of Mexico. That small half-degree increase in temperature of the sea's surface is the equivalent energy of about a million atomic bombs. Then you start to see the size of the problem."

NASA   Rising sea temperatures (yellow to red on this scale) are fuelling more powerful hurricanes

More…

- Watch 'When Nature Strikes Back: Floods' documentary

- Watch 'When Nature Strikes Back: Freakwaves' documentary

Video: Oklahoma Fury: Day Of The Tornadoes
The devastating Oklahoma tornadoes captured by daredevil tornado chasers.

- amazing images and videos from leading storm-chaser Mike Theiss

- NASA images of Katrina

- local newspaper photos of properties destroyed by Katrina

- National Hurricane Center