Do we need new 'category 6' for most extreme storms?

Hurricane Melissa was the second strongest Atlantic storm on record.

But future hurricanes could be even more intense.

So do we need a new top-tier, a 'category 6' for extreme winds?

At the moment, scientists classify storms by the five-level Saffir-Simpson scale. Melissa was right at the top, a category 5.

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So was Hurricane Katrina in 2005, which killed almost 1,400 people and caused $125bn (£95bn) in damage.

To make it into the top tier, a hurricane needs a sustained wind speed of 157 miles an hour.

But some scientists say the 50-year-old scale just doesn't cut it anymore as storms get more extreme. And we need a new top tier - a category 6 - for hurricanes with winds faster than 192 miles an hour.

Would Melissa reach the bar? Not quite. It had sustained windspeeds of 185mph.

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The strongest Atlantic storm on record, Hurricane Allen in 1980, had winds of 190mph.

So for now, a category 6 storm is just theoretical.

But global warming is making storms more intense, with rising sea temperatures driving the winds faster and faster.

Right now, the Caribbean is 2-3 degrees warmer than normal, so the destruction left behind by Melissa is climate change writ large.

If fossil fuel emissions keep on rising, there will be stronger hurricanes, and yes, ones which could reach that bar for category 6.