Under warmer temperatures, the natural state of the ocean is 70 feet higher than our civilization has been accustomed to for the last 5,000 years. Warmer temperatures are happening: we are now at 1.5F above the average and creeping upward. New observations show that Antarctica and Greenland ice loss is occurring faster than previous models predicted. The resulting rising sea levels will return Houston to the swampy marshland it was always meant to be.
(* or greenhouse gases, take your pick)