20 years later, a look at Katrina's lasting impact and concerns over future storms

It's been 20 years since Hurricane Katrina devastated the Louisiana, Mississippi and Alabama coasts. While Katrina remains the costliest U.S. natural disaster, the deepest impact is found in the human suffering and the difficult journey toward recovery. For our series Tipping Point, Lisa Desjardins explores the lessons learned — and what still lies ahead as weather has become more extreme.