TO GO WITH 'CLIMATE WARNING-COP21-PAKISTAN-ENVIRONMENT-GLACIER', FEATURE BY GUILLAUME LAVALL√ČE

In this photograph taken on September 28, 2015, a general view of Passu glacier is seen in Pakistan's Gojal Valley. Karachi, 2050: The sprawling megacity lies crumbling, dessicated by another deadly heatwave, its millions of inhabitants suffering life-threatening water shortages and unable to buy bread that has become too expensive to eat. It sounds like the stuff of dystopian fiction but it could be the reality Pakistan is facing. With its northern glaciers melting and its population surging -- the country's climate change time bomb is already ticking. AFP PHOTO / Aamir QURESHI        (Photo credit should read AAMIR QURESHI/AFP via Getty Images)