Every child comes with its blessing, the Egyptian saying goes.

With the country’s population now soaring beyond 100 million, that adage is being put to the test like never before. In the past three decades, the number of Egyptians has quadrupled and, if unchecked, could nearly double again by 2050, threatening to tip the host of this year’s global climate summit into a future where ever-scarcer resources thwart ambitious development efforts.

Omnia Abu Zaid’s husband invokes the saying repeatedly as they struggle to care for their four children.