Karachi’s poor learned long ago to cope with the many adversities that afflict Pakistan’s most crowded and chaotic city, including flooding, street violence and political crises. But since a suffocating heat wave descended on Karachi three days ago, killing at least 650 people, they have found no respite and no escape. “It’s so hot,” said a security guard, Shamim ur-Rehman, 34, as he sat on a cot, looking beleaguered. “There is no fan, there is nothing. I can’t sleep at night or during the day.” Prime Minister Nawaz Sharif declared an emergency on Tuesday as the death toll from the heat wave soared, with overwhelmed hospitals struggling to treat a surge of casualties and morgues filling to capacity. The army set up emergency treatment centers in the streets and the provincial government closed schools and city offices. The Edhi Foundation , which runs an ambulance service […]