Baroness Young, the head of the Environment Agency, says sooner or later the Broads will be lost to climate change.
The catastrophe could take up to a century to arrive - or it could be as little as a year, the Telegraph reports tonight.
The stark warning comes as the number of people signed up to an online Save The Broads petition on Gordon Brown's 10 Downing Street website nudges 500.
Click here to read the latest reports in full.
Click here to sign the petition.