Two things that human beings did contributed to the enormity of the New Orleans tragedy:
- The erosion of the wetlands due to casino and resort building
- Unnaturally warm ocean water in the gulf increased the strength of the hurricane, caused by global warming
Both of these man-made contributions to the Katrina disaster come to you courtesy of your Republican elected officials who have a long history of serving the private sector before they serve the public good.
Not to mention the fact that there is a hypoxic zone in the gulf where the Mississippi empties into it that is growing each year due to the vast amount of sediment caused by increasing amounts of impervious surfaces which causes an increase in the volume and flow rate of water in streams and rivers in the Mississippi watershed (which includes all but the most northern parts of Indiana).