Time is running out for Jakarta. One of the fastest-sinking cities on earth, environmental experts warn that one third of it could be submerged by 2050 if current rates continue.Decades of uncontrolled and excessive depletion of groundwater reserves, rising sea-levels, and increasingly volatile weather patterns mean swathes of it have already started to disappear.Existing environmental measures have had little impact, so authorities are taking drastic action: the nation will have a n