Seventy years after the worst natural disaster to strike the Netherlands, Chiem de Vos, seven at the time, still hears his neighbour's desperate cries of "My children are drowning!" ringing in his ears. As the Dutch this week commemorate the great flood of 1953, thoughts are turning to current-day climate change and how the low-lying country remains vulnerable to rising ocean levels. A witness and a historian reflect. IMAGES AND SOUNDBITES