* Worst-case assumes no move to defend coast
* UK, northern France among parts of Europe at risk
* U.S. states of Virginia, North Carolina also
By Simon Jessop
LONDON, July 30 (Reuters) - Failure to rein in climate
change and bolster sea defences could jeopardize up to a fifth
of the world's economic output by the end of the century, as
flooding threatens coastal countries worldwide, according to a
study released on Thursday.
From Bangladesh and India to Australia and even Britain,
rising sea levels already are leading to more frequent and
extreme flood events. With climate change causing polar ice to
melt and ocean waters to expand, economists have sought for
years to put a figure on the future potential damage.
The latest effort, published Thursday in the journal
Scientific Reports, paints one of the grimmest scenarios yet in
estimating the economic fallout from sea rise if the world
continues emitting greenhouse gases at the current rate.
Flood events that have typically occurred once in 100 years
"could occur as frequently as once in 10 years" for much of the
world, said the authors of the report, including researchers at
the universities of Amsterdam, Melbourne and the Global Climate
Forum.
This worst-case scenario would cost the world up to 20% of
its annual gross domestic product, given the impact on buildings
and other infrastructure, they said. Their estimates were based
on factors including the populations and assets at risk, and
models of tides, surges and sea levels around the world's
coasts.
Based on estimated 2019 GDP, that currently comes to around
$17.6 trillion.
However, the study's focus on the worst-case scenario - with
high emissions and no flood preparations - may be unrealistic,
said climate economist Thomas Schinko, deputy director of the
Risk and Resilience research programme at the International
Institute for Applied Systems Analysis in Vienna.
Already, "societies are reacting to changing coastal
flooding risks all over the world," said Schinko, who was not
involved in the new research. Though, "not all countries are
equally well equipped to adapt."
The study used computer simulations that accounted for
global tides, storm surges and wave data in gauging flood risks.
The bulk of the damage - 68% - would be caused by tide and
storm events, rather than sea level rise itself.
Areas that are now home to some 171 million would be
affected, with extensive flooding expected in northwest Europe,
including the UK and northern France, as well as in southeastern
China, Australia's Northern Territories, Bangladesh and the U.S.
states of North Carolina and Virginia.
Schinko said the work should be seen as "a strong signal to
the international policy scene to urgently strengthen the
ambitions for climate change mitigation".
(Reporting by Simon Jessop; Editing by Katy Daigle and Hugh
Lawson)