The Gulf Coast of the United States is increasingly vulnerable to hurricanes, a scientist has warned in a new study, 20 years after Katrina devastated New Orleans and hundreds of miles of coastline.

New Orleans and the Gulf Coast region are marking the 20-year anniversary of Hurricane Katrina, which occurred on Aug. 29, 2005.

Bush had taken what his staff called "working vacations" at the Crawford, Texas property throughout his presidency.