Flash floods wrought havoc in Bangladesh on Friday as the country recovers from weeks of political upheaval, with the death toll rising to 15 and millions more caught in the deluge. The South Asian nation of 170 million people, crisscrossed by hundreds of rivers, has seen frequent floods in recent decades. Monsoon rains cause widespread destruction every year, but climate change is shifting weather patterns and increasing the number of extreme weather events. “It’s a catastrophic situation here,” rescue volunteer Zahed Hossain Bhuiya, 35, told news publication AFP from the worst-hit city of Fe…