If you like to explore the depths . . . watch out. Global warming is already doing grave harm to prime diving locations.

Florida's coral reefs are likely to be early victims of climate change. Higher water temperatures, less sunlight because of rising seas, more nutrients washed into coastal waters -- these trends all threaten to kill off fragile coral systems, which can survive only within a narrow range of temperature, salinity, and water quality.

In fact, coral reef loss is already visible, with global warming one of several contributing factors. Elevated nutrient levels have caused coral reefs to be overrun by algae growth, while overfishing has depleted populations of fish that would consume the algae.

Over the next century, sea level rise and other effects of global warming will make matters worse by subjecting coral reefs to warmer and deeper water with even higher nutrient levels.

The Florida Keys also will be affected. Sea level rise will create new and wider gaps in the Keys, connecting coastal bays with coral reef tracts. This will severely strain adjacent coral communities by putting them in contact with warmer, deeper water containing higher nutrient levels and more stirred-up sediment.

Photo: John Halas, Florida Keys National Marine Sanctuary