New Scientist - 07.09.2019

7 September 2019 | New Scientist | 7

PARTS of Grand Bahama were

battered by the strongest winds

of hurricane Dorian for up to

15 hours on Monday, driving

a storm surge that inundated

most of the Caribbean island.

No land in or around the

Atlantic, and possibly worldwide,

has ever been subjected to such

powerful hurricane winds for so

long in recorded history.

By Tuesday, five deaths and

extreme damage to infrastructure

had been reported in the nearby

Abaco Islands, also part of The

Bahamas, which were struck first.

The full extent of the impact on

Grand Bahama is unlikely to

become clear for days. When New

Scientist went to press, the island

was still being hit by extreme

weather, even as Dorian weakened

from a category 5 to a category 3

hurricane and moved slowly away.

Dorian is now forecast to

move north up the US east coast.

Storm surges and heavy rain

are expected to cause extensive

damage there even if the eye of

the storm remains offshore.

The fastest winds in a hurricane

occur in the wall of the eye – the

clouds around the clear centre of

the storm – and drop off rapidly

further out. Since a hurricane

typically moves at least

15 kilometres an hour, the

strongest winds don’t usually

last long in any one place.

But Dorian isn’t only notable

as the joint strongest Atlantic

hurricane ever recorded to strike

land. It is also remarkable because

it slowed to a near halt over Grand

Bahama. This meant that parts

of the island remained in the eye

wall, with sustained wind speeds

of around 300km/h, for between

10 and 15 hours on Monday.

There is some evidence that

hurricanes are moving more

slowly due to global warming,

though what part if any this played

in Dorian’s stall isn’t yet clear.

Grand Bahama was also

inundated by a massive storm

surge of up to 7 metres, fuelled by

the intense winds. Video footage

showed the airport turned into an

inland sea and waves lapping at

the windows of houses.

Satellite images confirmed that

most of the low-lying island was

underwater on Monday. The

surge there was around 0.2 metres

higher than it would have been

without global warming – that is

how much sea level has risen due

to our carbon dioxide emissions.

It could rise by 3 metres by 2100.

Hurricanes are also expected

to intensify faster, to become

stronger overall and to dump

more rain as the world warms,

and that seems to be just what

is happening. All these factors

make storms far more damaging.

Grand Bahama may never fully

recover from the damage caused

by Dorian. Economic studies

suggest that growth and incomes

in areas hit by tropical cyclones

remain lower than they would

have been for decades after. ❚

Grand Bahama may have endured the longest pummelling ever by

the worst winds a hurricane can unleash. Michael Le Page reports

Dorian’s devastation

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